Patent Application
20130141013
1. Technical Field
The present invention relates to a light emission apparatus using LED chips, which emit light with wavelengths in a predetermined wavelength range from the visible light region to the near-ultraviolet region, and a wavelength conversion member which converts the wavelength of the light emitted by the LED chips, and an illumination system using the apparatus. The present invention also relates to an illumination method for forming desired synthetic light by converting the wavelength of the light emitted by the plurality of LED chips using the wavelength conversion member and synthesizing the light.
2. Background Art
As light sources of light emission apparatuses, incandescent bulbs and fluorescent lamps have come into widespread use. Recently, in addition to these light sources, a light emission apparatus, in which a semiconductor light emitting element such as a light emitting diode (LED) or an organic EL (OLED) is used as a light source, has been developed and used. In such a semiconductor light emitting element, it is possible to obtain various emission colors. Hence, a light emission apparatus, in which a plurality of semiconductor light emitting elements with different emission colors are combined and the respective emission colors are synthesized so as to generate radiant light with a desired color, has been also recently developed and used.
For example, JP-A-2006-4839 discloses a light emission apparatus in which red LEDs using LED chips having a red emission color, green LEDs using the LED chips having a green emission color, and blue LEDs using the LED chips having a blue emission color are combined, and desired white light is emitted by adjusting driving currents supplied to the respective LEDs and synthesizing the light emitted by the respective LEDs.
Originally, the emission spectrum width of LED chips themselves is relatively narrow. Hence, when the light emitted by the LED chips themselves is used in illumination as it is, a problem arises in that color rendering properties that are important matters in typical illumination light deteriorate. Therefore, in order to solve such a problem, there is provided an LED that converts a wavelength of the light emitted by LED chips using a wavelength conversion member such as a phosphor so as to emit light generated through wavelength conversion. For example, JP-A-2007-122950 discloses a light emission apparatus in which such LEDs are combined.
The light emission apparatus of JP-A-2007-122950 uses, in addition to blue LEDs using the LED chips having a blue emission color, green LEDs, in which a green phosphor excited by the light emitted from the LED chips is combined with the same LED chips, and red LEDs in which a red phosphor excited by the light emitted from the LED chips is combined with the same LED chips. The light emitted by the light emission apparatus ensures excellent color rendering properties by synthesizing the light respectively emitted by the blue LEDs, green LEDs, and red LEDs. In addition, by adjusting the optical output of each LED, it is possible to change the color of the light, which is emitted by the light emission apparatus, into various colors.
Generally, it is preferable that a light emission apparatus or an illumination apparatus be able to perform adjustment so as to generate white light with various color temperatures. However, in a similar manner to the light emission apparatus of JP-A-2007-122950, when a desired emission color is obtained by synthesizing the light respectively emitted by the blue LEDs, green LEDs, and red LEDs, for example, if the color temperature of the white light is intended to be changeable in a predetermined range, complex control for appropriately adjusting the driving currents supplied to the respective LEDs is necessary.
Further, in recent years, in light emission apparatuses other than incandescent bulbs, there has been a demand to generate the white light with desired emission intensity and color temperature by changing the emission intensity and the color temperature at the same time. That is, there has been a demand for control that can obtain white light having an optimum color temperature with respect to an optimum for the desired emission intensity by controlling the emission intensity and the color temperature at the same time. However, in such a light emission apparatus of JP-A-2007-122950, it is possible to generate white light with the desired color temperature through a complex control operation, but it is difficult to perform control so as to generate white light having the color temperature with respect to an optimum for the desired emission intensity mentioned above. In order to cope with such demands, for example, U.S. Pat. No. 7,288,902 discloses a light emission apparatus having desired emission intensity and color temperature by controlling the emission intensity and the color temperature at the same time.
The light emission apparatus of U.S. Pat. No. 7,288,902 uses: a plurality of light-emitting sources that emit white light with different color temperatures; a light control unit that controls the light by controlling a voltage waveform supplied from an alternating current voltage source so as to obtain a desired emission intensity; a phase angle detector that detects a phase angle relative to a light control level; a driver control section that determines the amounts of the driving currents supplied to the respective light-emitting sources on the basis of the phase angle information supplied from the phase angle detection unit; and a driver that supplies predetermined driving currents to the respective light-emitting sources in accordance with the instructions of the driver control section. As described above, in the light emission apparatus of U.S. Pat. No. 7,288,902, the amount of driving current supplied for each light-emitting source is determined on the basis of the phase angle information relating to the emission intensity. Hence, it is possible to generate the white light with the color temperature appropriate for the emission intensity.
Further, an illumination apparatus of WO 2009/063915 uses: a first light emission apparatus that emits white light with a first color temperature; and a second light emission apparatus that emits white light with a second color temperature higher than the first color temperature. In addition, each emission color of the first and second light emission apparatuses is determined such that a deviation Δuv from a black-body radiation locus in a chromaticity diagram of the CIE (1976) L*u*v* color coordinate system is in a range of −0.02 to +0.02. By adjusting the intensities of the light emitted by the respective first and second light emission apparatus, it is possible to change a color temperature of synthetic light emitted from the illumination apparatus in a range from the first color temperature to the second color temperature, and it is possible to generate white light which is natural without sense of discomfort.
The chromaticity of the white light emitted from such an illumination apparatus moves in the line, which connects the chromaticity point of the light emitted by the first light emission apparatus with the chromaticity point of the light emitted by the second light emission apparatus, in the XY chromaticity diagram of the CIE (1931) XYZ color coordinate system. Hence, it is possible to generate favorable white light without great deviation from the black-body radiation locus and sense of discomfort. However, in the XY chromaticity diagram, the black-body radiation locus is an upwardly convex curve. In contrast, the line, which connects the chromaticity point of the light emitted by the first light emission apparatus with the chromaticity point of the light emitted by the second light emission apparatus, is a straight line. Hence, at a certain color temperature, the deviation from the black-body radiation locus is large. Accordingly, in such an illumination apparatus, there is still much room for improvement in order to generate favorable white light.
Therefore, WO 2009/063915 also proposes an illumination apparatus in which the above-mentioned point is considered. That is, there is proposed an illumination apparatus using, in addition to the first and second light emission apparatuses, a third light emission apparatus of an emission color of which the color temperature is in the middle between the first color temperature and the second color temperature and the deviation Δuv from the black-body radiation locus is in the range of −0.02 to +0.02. In the illumination apparatus, by adjusting the intensities of the light respectively emitted by the first to third light emission apparatus, the chromaticity of the white light emitted from the illumination apparatus can be changed to be further satisfactorily approximate to the black-body radiation locus.
In the light emission apparatus disclosed in U.S. Pat. No. 7,288,902, all the light-emitting sources emit light in the entire range of the light control level. Hence, it is necessary to consider synthesis of the light emitted from a plurality of light-emitting sources in the entire range of the light control level, and thus a problem arises in that, in order to generate the white light with the desired color temperature, a process of calculating the driving currents supplied to the respective light-emitting sources becomes complicated every time. Such a problem more frequently arises when the number of light-emitting sources increases. Further, in the light emission apparatus disclosed in U.S. Pat. No. 7,288,902, the above-mentioned process of calculating the driving currents becomes complicated every time, and thus load on the driver control section and the driver increases. In order to reduce the load on the driver control section and the driver, the driver control section and the driver with high processing capabilities are necessary, while a problem arises in that manufacturing costs of the light emission apparatus increase.
Further, in the illumination apparatus of WO 2009/063915, the color temperature of the white light emitted from the illumination apparatus is set to be variable. However, when the color temperature of the white light is changed, the luminance is unlikely to be appropriately changed in accordance with the change. For example, the luminance may be excessively high when the color temperature is low, or the luminance may be excessively low when the color temperature is high. For this reason, a problem arises in that the change of the color temperature may give a sense of discomfort to a person.
Further, the illumination apparatus uses the first light emission apparatus that emits the white light with the first color temperature as a lower limit of the color temperature range. Hence, when the white light with the first color temperature is emitted from the illumination apparatus, only the white light emitted from the first light emission apparatus is used, and thus the second and third light emission apparatuses are turned off. Accordingly, when the white light with the first color temperature is emitted from the illumination apparatus as described above, or when the white light with a color temperature close to the first color temperature is emitted, a problem arises in that the total luminous flux of the illumination light obtained from the illumination apparatus excessively deteriorates.
The present invention has been made in view of such a problem, and provide a light emission apparatus capable of suppressing reduction in luminous flux inappropriate for adjustment of the color temperature while ensuring excellent color rendering properties, that is, a light emission apparatus capable of controlling the emission intensity and the color temperature so as to generate the light with a color temperature appropriate for the desired emission intensity and suppressing manufacturing costs, and an illumination system using the light emission apparatus. Further, the present invention provides an illumination method capable of emitting the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature while suppressing manufacturing costs of the light emission apparatus.
A light emission apparatus according an aspect of the present invention corresponds to a light emission apparatus of which a luminance is changed in accordance with change of a light control level, the light emission apparatus including: a wiring board; a plurality of LED chips that are disposed on an LED chip mounting surface of the wiring board and emit light with a predetermined wavelength range of a wavelength region ranging from a visible light region to a near-ultraviolet region, wherein the plurality of LED chips are grouped into a plurality of LED groups; a wavelength conversion member that is disposed at a position corresponding to the LED chip mounting surface of the wiring board, and is partitioned into a plurality of wavelength conversion regions corresponding to the plurality of LED chips, where the plurality of wavelength conversion regions are grouped into a plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has a different wavelength conversion characteristic, converts a wavelength of light emitted by the corresponding LED chips, and emits first-order light with a different color temperature; a current supply section that supplies a driving current to the LED chips independently for each of the LED groups through the wiring board; and a control section that controls the current supplied for each of the LED groups in response to a control signal input from outside, wherein the control section independently controls timing of starting to light the LED groups in accordance with the light control level.
The light emission apparatus may be configured so that the control section sequentially lights on the LED groups, in accordance with an increase in a total amount of the currents which are supplied from the current supply section to the plurality of LED groups.
The light emission apparatus may be configured so that the plurality of LED chips are grouped into three or more LED groups.
The light emission apparatus may be configured so that, in accordance with the increase in the total amount of the currents which are supplied from the current supply section to the plurality of LED groups, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with a lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with a higher color temperature.
The light emission apparatus may be configured so that the control section increases the number of LED groups which are being lighted on, in accordance with the increase in the total amount of the currents which are supplied from the current supply section to the plurality of LED groups.
The light emission apparatus may be configured so that the control section includes a phase angle detector that receives a control signal as a voltage waveform of which a conduction phase angle changes in accordance with the light control level and detects the conduction phase angle, and a selection circuit that selects an LED group to be lighted on in accordance with the conduction phase angle.
The light emission apparatus may be configured so that the control section receives a control signal as a voltage waveform in which an amplitude voltage value changes in accordance with the light control level, and selects an LED group to be lighted on in accordance with the amplitude voltage value.
A light emission apparatus according an aspect of the present invention corresponds to a light emission apparatus, including; a wiring board; a plurality of LED chips that are disposed on an LED chip mounting surface of the wiring board and emit light with a predetermined wavelength range of a wavelength region ranging from a visible light region to a near-ultraviolet region, wherein the plurality of LED chips are grouped into a plurality of LED groups; a wavelength conversion member that is disposed at a position corresponding to the LED chip mounting surface of the wiring board, and is partitioned into a plurality of wavelength conversion regions corresponding to the plurality of LED chips, where the plurality of wavelength conversion regions are grouped into a plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has a different wavelength conversion characteristic, converts a wavelength of light emitted by the corresponding LED chips, and emits first-order light with a different color temperature; a current supply section that supplies a driving current to the LED chips independently for each of the LED groups through the wiring board; and a control section that controls an amount of the current supplied for each of the LED groups in response to a control signal which is input from outside, wherein the control section sequentially lights on the LED groups, in accordance with an increase in a luminance of synthetic white light which is formed by synthesizing first-order light emitted from the plurality of wavelength conversion regions.
The light emission apparatus may be configured so that, in accordance with the increase in the luminance of the synthetic white light, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with a lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with a higher color temperature.
The light emission apparatus may be configured so that the plurality of LED chips and the wavelength changing member are separately provided from one another, a plurality of light emitting units are formed of the respective LED groups and the respective wavelength conversion regions corresponding to the LED groups, and each of the plurality of light emitting units is integrally provided, and the light emitting units form a light emitting unit group.
The light emission apparatus may be configured so that the wavelength changing member is provided to cover the plurality of LED chips, a plurality of light emitting units are formed of the respective LED groups and the respective wavelength conversion regions corresponding to the LED groups, and each of the plurality of light emitting units is individually provided, and the light emitting units form a light emitting unit group.
The light emission apparatus may be configured so that the plurality of LED chips and the wavelength conversion member form one package, and a plurality of packages are provided.
Further, as a specific configuration of an illumination system, it includes: a wiring board; a plurality of LED chips that are disposed on an LED chip mounting surface of the wiring board and emit light with a predetermined wavelength range of a wavelength region ranging from a visible light region to a near-ultraviolet region, wherein the plurality of LED chips are grouped into a plurality of LED groups; a wavelength conversion member that is disposed at a position corresponding to the LED chip mounting surface of the wiring board, and is partitioned into a plurality of wavelength conversion regions corresponding to the plurality of LED chips, where the plurality of wavelength conversion regions are grouped into a plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has a different wavelength conversion characteristic, converts a wavelength of light emitted by the corresponding LED chips, and emits first-order light with a different color temperature; a current supply section that supplies a driving current to the LED chips independently for each of the LED groups through the wiring board; an instruction section that gives an instruction to generate synthetic white light with a desired luminance by synthesizing the first-order light; a light control section that outputs a control signal for changing a luminance of the synthetic white light in response to the instruction from the instruction section; and a control section that controls an amount of the current supplied for each of the LED groups in response to a control signal which is output from the light control section, wherein the control section sequentially lights on the LED groups, in accordance with an increase in the luminance of the synthetic white light.
The illumination system may be configured so that, in accordance with the increase in the luminance of the synthetic white light, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with a lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with a higher color temperature.
The illumination system may be configured so that the control section increases the number of LED groups which are being lighted on, in accordance with the increase in the luminance of the synthetic white light.
The illumination system may be configured so that the control signal output from the light control section is a voltage waveform, and a conduction phase angle of the voltage waveform changes in accordance with the instruction from the instruction section, and the control section includes a phase angle detector that detects the conduction phase angle, and a selection circuit that selects an LED group to be lighted on in accordance with the conduction phase angle.
The illumination system may be configured so that the control signal output from the light control section is a voltage waveform, and an amplitude voltage value of the voltage waveform changes in accordance with the instruction from the instruction section, and the control section selects an LED group to be lighted on in accordance with the amplitude voltage value.
The illumination system may be configured so that the control section increases a sum of the driving currents, each of which is supplied for each of the LED groups, in accordance with change of a light control level toward increasing the luminance of the synthetic white light.
The illumination system may be configured so that the control section changes a target luminous flux φ in accordance with a target correlation color temperature T, and sets the target correlation color temperature and a target total luminous flux such that a constant A0, at which the following inequality expression is established, is present:
−80743−(1000/T)5+164973−(1000/T)4−135260−(1000/T)3+57994−(1000/T)2−13995−(1000/T)+1632.9<φ/A0<exp{−342.11−(1000/T)3+450.43−(1000/T)2−212.19×(1000/T)+39.47}.
Further, an illumination method includes: supplying a current independently to each LED group of a plurality of LED chips grouped into a plurality of LED groups so as to cause each LED group to emit light; supplying the light emitted by the LED chip to a wavelength conversion member that is partitioned into a plurality of wavelength conversion regions corresponding to the plurality of LED chips, where the plurality of wavelength conversion regions are grouped into a plurality of wavelength conversion regions corresponding to the LED groups, wherein each wavelength conversion region has a different wavelength conversion characteristic, and emits first-order light with a different color temperature; and forming synthetic white light by synthesizing the first-order light, wherein the LED groups are sequentially lighted on by controlling an amount of the current supplied for each LED group in accordance with an increase in a luminance of the synthetic white light.
The illumination method may be configured so that, in accordance with the increase in the luminance of the synthetic white light, the LED groups are sequentially lighted on in an order from an LED group corresponding to the wavelength conversion region emitting the first-order light with a lower color temperature to an LED group corresponding to the wavelength conversion region emitting the first-order light with a higher color temperature.
Further, a light emission apparatus according to an aspect of the present invention includes: a light emitting unit group that is formed of two or more light emitting units, each of which emits light with a different chromaticity, wherein the light emitting unit group emits synthetic light which is formed by synthesizing first-order light emitted from the respective light emitting units; and control means for controlling light emission of each light emitting unit such that a chromaticity point of the synthetic light emitted from the light emitting unit group is positioned on a control curve which is set in advance in a range from a first color temperature in an XY chromaticity diagram of a CIE (1931) XYZ color coordinate system to a second color temperature higher than the first color temperature, wherein the control means includes a target value setting section that sets one parameter of a target total luminous flux φ and a target correlation color temperature T of the synthetic light emitted from the light emitting unit group and sets the other parameter in accordance with the one parameter, and an emission control section that controls light emission of each light emitting unit such that a color temperature and a total luminous flux of the synthetic light emitted from the light emitting unit group are equal to the target total luminous flux φ and the target correlation color temperature T set by the target value setting section, and the target setting section sequentially changes the target correlation color temperature T in at least a range from 3500 K to 4500 K, and sets the target total luminous flux φ at 4500 K not less than twice and not more than thirty times the target total luminous flux φ at 3500 K in correspondence with a desired illuminance of an irradiated object, which is irradiated with the synthetic light, with respect to the light emission apparatus.
The light emission apparatus may be configured so that the target setting section sets the target total luminous flux φ such that an illuminance of the irradiated object at 3500 K is in a range from 100 Lux to 500 Lux and an illuminance of the irradiated object at 4500 K is in a range from 300 Lux to 40000 Lux.
The light emission apparatus may be configured so that the target setting section sequentially changes the target correlation color temperature T in a range from 2000 K to 4500 K, and sets the target total luminous flux φ at 4500 K not less than ten times and not more than one hundred times the target total luminous flux φ at 2000 K in correspondence with a range of the desired illuminance.
The light emission apparatus may be configured so that the target setting section sets the target total luminous flux φ such that an illuminance of the irradiated object at 2000 K is in a range from 15 Lux to 20 Lux and an illuminance of the irradiated object at 4500 K is in a range from 300 Lux to 40000 Lux.
The light emission apparatus may be configured so that the target value setting section sets the target total luminous flux φ, in a setting range from a lower limit to an upper limit of the target correlation color temperature T, such that a constant A0, at which the following inequality expression is established, is present:
−80743−(1000/T)5+164973−(1000/T)4−135260−(1000/T)3+57994−(1000/T)2−13995−(1000/T)+1632.9<φ/A0<exp{−342.11−(1000/T)3+450.43−(1000/T)2−212.19×(1000/T)+39.47}.
As a specific configuration, it may be configured so that the number of the light emitting units is three or more.
Further, a light emission apparatus according to the present invention includes: a light emitting unit group that is formed of three or more light emitting units, each of which emits light with a different chromaticity, wherein the light emitting unit group emits synthetic light which is formed by synthesizing first-order light emitted from the respective light emitting units; and control means for controlling light emission of each light emitting unit such that a chromaticity point of the synthetic light emitted from the light emitting unit group is positioned on an upwardly convex control curve which is set in advance in a range from a first color temperature in an XY chromaticity diagram of a CIE (1931) XYZ color coordinate system to a second color temperature higher than the first color temperature, wherein the control means includes a target value setting section that sets a target correlation color temperature T and a target total luminous flux φ of the synthetic light emitted from the light emitting unit group, and an emission control section that controls light emission of each light emitting unit such that a color temperature and a total luminous flux of the synthetic light emitted from the light emitting unit group are equal to the target correlation color temperature T and the target total luminous flux φ set by the target value setting section, the target value setting section changes the target luminous flux φ in accordance with the target correlation color temperature T, and sets the target correlation color temperature T and a target total luminous flux φ such that a constant A0, at which the following inequality expression is established, is present:
−80743−(1000/T)5+164973−(1000/T)4−135260−(1000/T)3+57994−(1000/T)2−13995−(1000/T)+1632.9<φ/A0<exp{−342.11−(1000/T)3+450.43−(1000/T)2−212.19×(1000/T)+39.47},
and in the XY chromaticity diagram, chromaticity of the first-order light emitted by each light emitting unit is determined such that the control curve is included in a polygon defined by vertices of chromaticity points of the first-order light emitted by the respective light emitting units.
According to the light emission apparatus, it is possible to generate the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature, and to suppress the manufacturing costs thereof.
Further, in the above-mentioned light emission apparatus, when the corresponding LED groups are sequentially lighted on in accordance with the increase in the total amount of the currents supplied to the plurality of LED groups, it is possible to increase the luminance of the synthetic white light emitted from the light emission apparatus, and change the color temperature of the corresponding synthetic white light appropriate for the increase in the corresponding luminance.
Further, in the above-mentioned light emission apparatus, when the plurality of LED chips are grouped into three or more LED groups, the synthetic white light emitted from the light emission apparatus can be changed in accordance with the black-body radiation locus in the xy chromaticity diagram of the CIE (1931) XYZ color coordinate system.
Furthermore, in the above-mentioned light emission apparatus, in accordance with the increase in the luminance of the synthetic white light, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with the lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with the higher color temperature. In this case, it is possible to increase the luminance of the synthetic white light emitted from the light emission apparatus, and change the color temperature of the corresponding synthetic white light appropriate for the increase in the corresponding luminance.
In addition, in the above-mentioned light emission apparatus, in accordance with the increase in the total amount of the currents supplied to the LED groups, the number of LED groups, which are being lighted on, increases. In this case, while increasing the luminance of the synthetic white light emitted from the light emission apparatus, it is possible to change the color temperature of the synthetic white light.
Moreover, in the light emission apparatus, the above-mentioned control signal is a voltage waveform. Hence, by using an existing illumination system, it is possible to use the light emission apparatus.
A further specific configuration of the light emission apparatus is as follows. The plurality of LED chips and the wavelength conversion member are provided to be separated from one another, the plurality of light emitting units are formed of the respective LED groups and the respective wavelength conversion regions corresponding to the LED groups, each of the plurality of light emitting units is integrally provided, and the light emitting units form a light emitting unit group. In this case, it is easy to treat the light emitting unit group, and thus it is possible to reduce the number of manufacturing processes and the manufacturing costs of the light emission apparatus.
A further specific configuration of the light emission apparatus is as follows. The wavelength conversion member is provided to cover the plurality of LED chips, the plurality of light emitting units are formed of the respective LED groups and the respective wavelength conversion regions corresponding to the LED groups, each of the plurality of light emitting units is individually provided, and the light emitting units form a light emitting unit group. In this case, a degree of freedom of arrangement of the light emitting units increases.
According to the illumination system, it is possible to generate the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature, and to suppress the manufacturing costs thereof.
Further, in the above-mentioned illumination system, in accordance with the increase in the luminance of the synthetic white light, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with the lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with the higher color temperature. Hence, when increasing the luminance of the synthetic white light supplied from the corresponding illumination system, it is possible to change the color temperature of the corresponding synthetic white light appropriate for the increase in the corresponding luminance.
Furthermore, according to the illumination method, it is possible to emit the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature while suppressing manufacturing costs of the light emission apparatus.
In addition, in the above-mentioned illumination method, in accordance with the increase in the luminance of the synthetic white light, the LED groups are sequentially lighted on in an order from the LED group corresponding to the wavelength conversion region emitting the first-order light with the lower color temperature to the LED group corresponding to the wavelength conversion region emitting the first-order light with the higher color temperature. In this case, the synthetic white light generated by the illumination method has a color temperature appropriate for the desired luminance obtained by the light control.
In the light emission apparatus, the light emitting unit group is formed of three or more light emitting units, each of which emits first-order light with a different chromaticity, and the control means controls light emission of each light emitting unit such that the chromaticity point of the synthetic light emitted from the light emitting unit group is positioned on the upwardly convex control curve which is set in advance in the range from the first color temperature to the second color temperature in the XY chromaticity diagram of the CIE (1931) XYZ color coordinate system. At this time, in the XY chromaticity diagram, chromaticity of the first-order light emitted by each light emitting unit is determined such that the control curve is included in a polygon, which is formed by connecting the respective chromaticity points of the first-order light emitted by the respective light emitting units. Hence, it is possible to control the light, which is emitted from the light emission apparatus, such that it has the desired chromaticity. For example, by performing the color control and the light control on the basis of the black-body radiation locus, it is possible to provide more comfortable illumination.
Further, the emission control section controls the light emission of each light emitting unit such that the color temperature of the synthetic light emitted from the light emitting unit group is equal to the target correlation color temperature set by the target value setting section of the control means. Hence, the amount of emission control of the light emitting unit corresponding to the target correlation color temperature is stored in advance in the storage device for each light emitting unit. Thereby, it is possible to eliminate the necessity to repeatedly calculate the amount of emission control from the target correlation color temperature, and thus it is possible to reduce calculation load on the control means.
Furthermore, when the emission control section controls light emission of each light emitting unit on the basis of the target correlation color temperature which is set by the target value setting section, the emission control section also controls the total luminous flux of the synthetic light emitted from the light emitting unit group. Hence, when changing the color temperature of the illumination light of the illumination apparatus into various values, it is also possible to control the total luminous flux of the illumination light in accordance with the purpose of use of the illumination apparatus or user's request. For example, in a case of the incandescent bulb, when the luminance thereof is changed, as the luminance becomes lower, the color temperature becomes lower. Therefore, by changing the illumination light of the illumination apparatus in a similar manner to change of the illumination light generated by such an incandescent bulb, it is possible to eliminate sense of discomfort at the time of adjusting the illumination light. Alternatively, in accordance with the purpose of use of the illumination apparatus, the luminance may not be intended to be excessively reduced even at a low color temperature. However, it is possible to change such illumination light.
In addition, the control section changes the target luminous flux φ in accordance with the target correlation color temperature T, and sets the target correlation color temperature T and the target total luminous flux φ such that the constant A0, at which the following inequality expression is established, is present:
−80743−(1000/T)5+164973−(1000/T)4−135260−(1000/T)3+57994−(1000/T)2−13995−(1000/T)+1632.9<φ/A0<exp{−342.11−(1000/T)3+450.43−(1000/T)2−212.19×(1000/T)+39.47}.
In the XY chromaticity diagram, the chromaticity of the first-order light emitted by each light emitting unit is determined such that the control curve is included in the polygon defined by vertices of the chromaticity points of the first-order light emitted by respective light emitting units. Hence, the light, which is generated from the light emission apparatus, is made to provide a sense of comfort all the time when the color temperature is changed.
a) to 15(d) are schematic diagrams illustrating modified examples of pattern shapes of wavelength conversion regions and LED groups used in the light emission apparatus according to the first example of the present invention.
a) and 17(b) are schematic diagrams illustrating cell regions used in the modified example of the light emission apparatus according to the first example of the present invention.
a) is a graph illustrating relationships between the total luminous fluxes of and the color temperatures of the synthetic white light emitted from the light emission apparatus when the driving current is applied to the light emission apparatus according to the second example, and
Hereinafter, referring to the drawings, embodiments of the present invention will be described in detail on the basis of several examples. In addition, the present invention is not limited to the description below, and may be arbitrarily modified without departing from the technical scope of the invention. Further, all the drawings used in description of the examples schematically illustrate the light emission apparatuses according to the present invention. In order to facilitate understanding, the drawings may be partially emphasized, enlarged, reduced, or omitted, and thus the scale sizes, the shapes, and the like of the components may not exactly reflect those in actual situations. Furthermore, all the various numerical values used in the examples are exemplary values, and thus can be changed to various different values.
In addition, the material of the wiring board 2 is not limited to the alumina ceramic, and the main body of the wiring board 2 may be formed of a material selected from, for example, resin, glass epoxy, and composite resin containing a filler as materials with excellent electrical insulation. Alternatively, in order to improve a light emitting efficiency of the light emitting section 1 by enhancing reflectivity of light on the chip mounting surface 2a of the wiring board 2, it is preferable to use silicon resin including a white pigment such as alumina powder, silica powder, magnesium oxide, or titanium oxide. On the other hand, in order to obtain a further excellent heat dissipation ability, the main body of the wiring board 2 may be made of metal. In this case, it is necessary to electrically insulate the wiring patterns and the like of the wiring board 2 from the main body made of metal.
As shown in
A fluorescent member 5 is divided and grouped into two wavelength conversion regions of a first wavelength conversion region P1 and a second wavelength conversion region P2. In accordance with the division of the fluorescent member 5, the LED chips 3 mounted on the wiring board 2 are grouped into respective LED groups corresponding to respective positions of the first wavelength conversion region P1 and the second wavelength conversion region P2 as shown in
Accordingly, in the present example, respective combinations of the first wavelength conversion region P1 and the second wavelength conversion region P2 and the first LED group D1 and the second LED group D2 corresponding thereto correspond to respective light emitting units of the present invention. That is, the first LED group D1 and the first wavelength conversion region P1 constitute a first light emitting unit U1, and the second LED group D2 and the second wavelength conversion region P2 constitute a second light emitting unit U2. A light emitting section 1, in which the two light emitting units are integrated, corresponds to a light emitting unit group of the present invention. In the present example, the first light emitting unit U1 and the second light emitting unit U2 are integrally provided, and constitute the light emitting section 1 which is the light emitting unit group. Note that, in the description below, light, which is emitted by each of the first light emitting unit U1 and the second light emitting unit U2, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first light emitting unit U1 and the second light emitting unit U2 and is emitted from the light emitting section 1, is referred to as synthetic white light.
The clearance provided herein is formed with a distance L1 calculated in advance such that the light emitted from the LED chips 3 reliably reaches the fluorescent member 5 positioned to correspond to the LED chips 3. When the LED chips 3 is as close to the fluorescent member 5 as possible, the light emitted by the LED chips 3 reliably reaches the fluorescent member 5. However, when the LED chips 3 is excessively close to the fluorescent member 5, the fluorescent member 5 is heated by heat emitted by the LED chips 3, and thus there is a concern that this may cause deterioration in the wavelength conversion function and the light emitting efficiency. Hence, in order to prevent the temperature from being excessively increased, it is preferable that the distance between the LED chips 3 and the fluorescent member 5 be equal to or greater than 0.01 mm.
Further, when the light emitting section 1 has thermal room, the first surface 4a of the transparent board 4 may be in close contact with the LED chips 3 without providing such a clearance. Furthermore, even when the LED chips 3 and the transparent board 4 are separated, the clearance may be sealed by silicon resin, epoxy resin, glass, or the like which is transparent. In such a manner, it is possible to efficiently guide the light emitted from the LED chips 3 to the fluorescent member 5.
In addition, in the present example, the fluorescent member 5 is provided on the second surface 4b of the transparent board 4, but the fluorescent member 5 may be provided on the first surface 4a of the transparent board 4, that is, a surface thereof close to the wiring board 2. Even in this case, in a similar manner to the present example, it is possible to provide an appropriate clearance between the fluorescent member 5 and the LED chips 3. However, when there is thermal room, it is possible to cause the fluorescent member 5 to be in close contact with the LED chips 3 or to be close thereto just before the contact.
(LED Chip)
As the LED chip 3, in the present example, an LED chip emitting blue light with a peak wavelength of 460 nm is used. Specifically, as such an LED chip, there is a GaN LED chip in which for example an InGaN semiconductor is used in a light emitting layer. Note that, the emission wavelength characteristic and the type of the LED chip 3 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. In the present example, it is preferable that the peak wavelength of the light emitted by the LED chips 3 be in the wavelength range of 420 nm to 500 nm.
A p electrode 7 and an n electrode 8 are formed on a surface of each LED chip 3 facing the wiring board 2. In a case of the LED chip 3 shown in
Note that, a method of mounting the LED chips 3 on the wiring board 2 is not limited to this, and it may be possible to select a method appropriate for the type, the structure, and the like of the LED chip 3. For example, after the LED chips 3 are fixedly attached to predetermined positions on the wiring board 2, the two electrodes of each LED chip 3 may be connected to the corresponding wiring patterns through wire bonding. In addition, one electrode may be bonded to the corresponding wiring pattern as described above, and the other electrode may be connected to the corresponding wiring pattern through wire bonding.
(Fluorescent Member)
As described above, the fluorescent member 5 is divided into two of the first wavelength conversion region P1 and the second wavelength conversion region P2 corresponding to the first LED group D1 and the second LED group D2. In the first wavelength conversion region P1 and the second wavelength conversion region P2, the wavelengths of the light emitted from the LED chips 3 are converted, and various phosphors for emitting light with various wavelengths are held in a distributed manner. The used various phosphors include: a red phosphor (first phosphor) which is for emitting red light by converting the wavelength of the blue light emitted by the LED chips 3; a green phosphor (second phosphor) which is for emitting green light by converting the wavelength of the blue light emitted by the LED chips 3; and a yellow phosphor (third phosphor) which is for emitting yellow light by converting the wavelength of the blue light emitted by the LED chips 3. In addition, it may be possible to use an orange phosphor (fourth phosphor) which is for emitting orange light by converting the wavelength of the blue light emitted by the LED chips 3. Further, it is not necessary for the fluorescent member 5 to hold all the above-mentioned red phosphor, green phosphor, and yellow phosphor in a distributed manner, and if the desired first-order light can be emitted from the fluorescent member 5, one type or two or more types of phosphors may be selected from the above-mentioned phosphors. For example, the fluorescent member 5 may hold the red phosphor and the green phosphor in a distributed manner, and may not hold the yellow phosphor in a distributed manner.
Here, specific examples of the above-mentioned phosphors will be described below. Note that, the phosphors exemplify phosphors quite appropriate for the present example. However, available phosphors are not limited thereto, and it may be possible to apply various types of phosphors insofar as they are within the technical scope of the present invention.
(Red Phosphor)
An appropriate wavelength range of the emission peak wavelength of the red phosphor is normally 570 nm or more and 780 nm or less, preferably 580 nm or more and 700 nm or less, or more preferably 585 nm or more and 680 nm or less. From this point of view, as the red phosphor, for example, the following are preferable: (Ca,Sr,Ba)2Si5(N,O)8:Eu; (Ca,Sr,Ba)Si(N,O)2:Eu; (Ca,Sr,Ba)AlSi(N,O)3:Eu; (Sr,Ba)3SiO5:Eu; (Ca,Sr)S:Eu; SrAlSi4N7:Eu; (La,Y)2O2S:Eu; β-diketone Eu complexes such as Eu(dibenzoylmethane)3-1,10-phenanthroline complex; carboxylic acid Eu complex; and K2SiF6:Mn. In addition, the following are more preferable: (Ca,Sr,Ba)2Si5(N,O)8:Eu; (Sr,Ca)AlSi(N,O)3:Eu; SrAlSi4N7:Eu; (La,Y)2O2S:Eu; and K2SiF6:Mn (here, some Si may be replaced with Al or Na).
(Green Phosphor)
An appropriate wavelength range of the emission peak wavelength of the green phosphor is normally 500 nm or more and 550 nm or less, preferably 510 nm or more and 542 nm or less, or more preferably 515 nm or more and 535 nm or less. From this point of view, as the green phosphor, for example, the following are preferable: Y3(Al,Ga)5O12:Ce; CaSc2O4:Ce; Ca3(Sc,Mg)2Si3O12:Ce; (Sr,Ba)2SiO4:Eu; (Si,Al)6(O,N)8:Eu(β-sialon); (Ba,Sr)3Si6O12:N2:Eu; SrGa2S4:Eu; BaMgAl10O17:Eu; and Mn.
(Yellow Phosphor)
An appropriate wavelength range of the emission peak wavelength of the yellow phosphor is normally 530 nm or more and 620 nm or less, preferably 540 nm or more and 600 nm or less, or more preferably 550 nm or more and 580 nm or less. From this point of view, as the yellow phosphor, for example, the following are preferable: Y3Al5O12:Ce; (Y,Gd)3Al5O12:Ce; (Sr,Ca,Ba,Mg)2SiO4:Eu; (Ca,Sr)Si2N2O2:Eu; α-sialon; and La3Si6N11:Ce (here, a part thereof may be replaced with Ca or O).
(Orange Phosphor)
The orange phosphor, of which the emission peak wavelength is in the range of 580 nm or more and 620 nm or less or preferably in the range of 590 nm or more and 610 nm or less, can be appropriately used instead of the red phosphor. Examples of such an orange phosphor include: (Sr,Ba)3SiO5:Eu; (Sr,Ba)2SiO4:Eu; (Ca,Sr,Ba)2Si5(N,O)8:Eu; (Ca,Sr,Ba)AlSi(N,O)3:Ce; and the like.
Further, the first wavelength conversion region P1 and the second wavelength conversion region P2 are different in the mass and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor. Accordingly, the ratios of the red light, the green light, and the yellow light, which are emitted from the first wavelength conversion region P1 through the wavelength conversion, to the blue light, which is emitted without the wavelength conversion, and the ratios of the red light, the green light, and the yellow light, which are emitted from the second wavelength conversion region P2 through the wavelength conversion, to the blue light, are different from each other. Hence, there are differences among color temperatures of: the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the first wavelength conversion region P1; and the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the second wavelength conversion region P2.
Note that, the numbers of phosphors, which are held in a distributed manner in the first wavelength conversion region P1 and the second wavelength conversion region P2, may be different from each other. For example, the red phosphor is held in a distributed manner only in the first wavelength conversion region P1, whereby the color temperatures of the first-order light respectively emitted from the first wavelength conversion region P1 and the second wavelength conversion region P2 are made to be different from each other.
Next, referring to
Note that, the y value of the CIE (1931) XYZ color coordinate system at any chromaticity point of the first-order light, which is emitted from each of the first light emitting unit U1 and the second light emitting unit U2, is preferably equal to or less than 0.65. When the y value is greater than 0.65, the takeoff efficiency of the visible light of each light emitting unit deteriorates, and it is difficult for the overall light emission apparatus to efficiently emit light. On the other hand, when LED chips emitting near-ultraviolet light to be described later are used instead of the LED chips 3 emitting the blue light, there is no trouble even if the y value is greater than 0.65.
By determining the mixture ratio of the phosphors in each wavelength conversion region in the above-mentioned method, it is possible to make the color temperature of the first-order light emitted from the second light emitting unit U2 higher than the color temperature of the first-order light emitted from the first light emitting unit U1.
In the present example, as the red phosphor, (Sr, Ca)1AlSiN3:Eu is used, as the green phosphor, Ca3(Sc, Mg)2Si3O12:Ce is used, and as the yellow phosphor, Y3Al5O12:Ce is used. Further, as shown in
Furthermore, the first wavelength conversion region P1 and the second wavelength conversion region P2 have different film thicknesses. Specifically, as shown in
(Electric Circuit Configuration of Light Emission Apparatus)
As described above, in the light emission apparatus of the present example, the color temperatures of the first-order light, which are respectively emitted from the first light emitting unit U1 and the second light emitting unit U2, are set to be different from each other, and the synthetic white light, which is generated by synthesizing the first-order light emitted from the light emitting units, is emitted from the light emission apparatus. Accordingly, in the light emission apparatus of the present example, by changing the total luminous flux (that is, emission intensity or luminance) of the first-order light emitted from each of the first light emitting unit U1 and the second light emitting unit U2, the total luminous flux of the synthetic white light emitted from the light emission apparatus is adjusted, and the color temperature of the synthetic white light is changed in accordance with the corresponding total luminous flux of the synthetic white light so as to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux mentioned above. Description will be given below of the electric circuit of the light emission apparatus configured to emit the synthetic white light with the color temperature appropriate for the above-mentioned desired intensity and corresponding total luminous flux, with reference to
The light emitting section 1 has the LED chips 3a of the first LED group D1 and the LED chips 3b of the second LED group D2. In specific configurations of the first LED group D1 and the second LED group D2, the LED chips 3a of the first LED group D1 are connected to one another in series such that the polarities thereof are the same. Likewise, the 10 LED chips 3b of the second LED group D2 are also connected to one another in series such that the polarities thereof are the same. Further, the first LED group D1 and the second LED group D2 are connected in parallel through a switch circuit 15c to be described later. Note that, the connection form of the LED chips 3 in the same LED group is not limited to serial connection, and may be, for example, parallel connection in which the LED chips 3 are connected to one another in parallel such that the polarities thereof are the same.
The light control section 13 is connected to the instruction section 14, the current supply section 15, the control section 16, and an alternating current voltage source VAC. The light control section 13 controls the conduction phase angle of the waveform of the alternating current voltage supplied from the alternating current voltage source VAC in response to an instruction signal (signal representing the light control level) supplied from the instruction section 14, thereby generating the alternating-current light control voltage VDIM(AC). Further, the light control section 13 supplies the generated light control voltage VDIM(AC) to the current supply section 15 and the control section 16. For example, the light control section 13 is a light control circuit formed by a triac (bidirectional thyristor) used as a phase control element.
Here, the light control level can be represented by the following expression.
Light Control Level=(1−Actual Supply Current/Maximum Supply Current)×100 [Numerical Expression 1]
The maximum supply current is a maximum current which is supplied to the light emission apparatus 11 (more specifically, the light emitting section 1), and the actual supply current is a current which is practically supplied to the light emission apparatus 11 (more specifically, the light emitting section 1). That is, when the light control level is 0%, the maximum current is supplied to the light emitting section 1, and as the light control level increases, the amount of current supplied to the light emitting section 1 decreases.
The instruction section 14 includes, as shown in
The current supply section 15 is formed of a rectifier circuit 15a, a voltage current conversion circuit 15b, and the switch circuit 15c. The rectifier circuit 15a is a full-wave rectifier circuit formed of four diodes, or a half-wave rectifier circuit formed of a single diode. The rectifier circuit 15a is connected to the light control section 13, and converts the alternating-current light control voltage VDIM(AC), which is supplied from the light control section 13, into the direct-current light control voltage VDIM(Dc). The voltage current conversion circuit 15b converts the direct-current light control voltage VDIM(DC), which is supplied from the rectifier circuit 15a, into the driving currents which are supplied to the LED chips 3. Accordingly, the driving current increases or decreases in accordance with the conduction phase angle. The switch circuit 15c includes transistors Q1 and Q2. Each collector of the transistors Q1 and Q2 is connected to a terminal closest to a cathode of each of the first LED group D1 and the second LED group D2, each emitter of the transistors Q1 and Q2 is connected to the voltage current conversion circuit 15b, and each base of the transistors Q1 and Q2 is connected to the control section 16. Note that, the current supply section 15 may provide AC driving currents to the LED chips 3 without the rectifier circuit 15a. In this case, the LED chips 3 periodically emit light.
Due to the configuration and the connection relationship of the light control section 13, the instruction section 14, and the current supply section 15 mentioned above, it is possible to adjust the amount of driving current (the amount of supply current), which is supplied to the LED chips 3, only by rotating the operation dial 14a. In addition, by adjusting the amount of supply current supplied to the light emitting section 1, it is possible to emit (that is, control) the synthetic white light with the desired total luminous flux from the light emission apparatus 11.
The control section 16 includes a phase angle detector 16a, a memory 16b, and a selection circuit 16c. The phase angle detector 16a is connected to the light control section 13, and detects the conduction phase angle controlled by the light control section 13. The memory 16b stores voltage value data on the value of the voltage to be supplied to the bases of the transistors Q1 and Q2 in accordance with the conduction phase angle. Here, the voltage value data is not data for only turning on or off the transistors Q1 and Q2, but data for changing the magnitude of the driving currents, which are respectively supplied to the first LED group D1 and the second LED group D2 from the voltage current conversion circuit 15b, by changing the voltage values of the base voltages VS applied to the bases of the transistors Q1 and Q2. The selection circuit 16c cross-checks the conduction phase angle, which is detected by the phase angle detector 16a, with the voltage value data stored in the memory, and determines the voltage values of the base voltages VS applied to the transistors Q1 and Q2. Then, the selection circuit 16c applies the base voltages VS with the determined voltage values to the bases of the transistors Q1 and Q2.
As described above, the control section 16 independently turns on the transistors Q1 and Q2 in accordance with the alternating-current light control voltage VDIM(AC). Thus, it is possible to emit the first-order light from both of the light emitting unit U1 and the light emitting unit U2 or either one of the light emitting unit U1 and the light emitting unit U2, in accordance with the total luminous flux of the synthetic white light emitted from the light emitting section 1. Further, the control section 16 changes the voltage values of the base voltages VS applied to the bases of the transistors Q1 and Q2 in response to the light control level so as to change the magnitudes of the driving currents respectively supplied to the first LED group D1 and the second LED group D2 from the voltage current conversion circuit 15b. Hence, it is possible to adjust the total luminous flux of the first-order light emitted from the light emitting unit U1 and the light emitting unit U2. In addition, as described above, the first wavelength conversion region P1 and the second wavelength conversion region P2 are different from each other in the weights, the mixture ratios, and the film thicknesses of the phosphors. Hence, the color temperatures of the first-order light emitted from the first wavelength conversion region P1 and the second wavelength conversion region P2 are different. Therefore, in the light emission apparatus 11 according to the present example, when the light control level is changed in order to obtain the desired total luminous flux, it is also possible to change the color temperature of the synthetic white light emitted from the light emission apparatus 11 in accordance with the corresponding light control level.
(Control of Light Emitting Section)
When a user of the light emission apparatus 11 operates the operation dial 14a, the main body 14b of the instruction section 14 detects the position of the operation dial 14a, and supplies the instruction signal (signal representing the light control level) based on the detected position of the operation dial 14a to the light control section 13. The light control section 13 controls the conduction phase angle of the waveform of the alternating current voltage, which is supplied from the alternating current voltage source VAC, on the basis of the instruction signal supplied from the instruction section 14, thereby generating the alternating-current light control voltage VDIM(AC). In a specific control method, the light control section 13 inputs a trigger pulse with an arbitrary phase difference relative to the zero cross point of the sinusoidal waveform of the alternating current supplied from the alternating current voltage source so as to control the conduction phase angle. Accordingly, when the supplied instruction signal is changed, the light control section 13 controls the conduction phase angle by changing the phase difference of the trigger pulse in accordance with the change.
The rectifier circuit 15a of the current supply section 15 converts the alternating-current light control voltage VDIM(AC), which is supplied from the light control section 13, into the direct-current light control voltage VDIM(DC), and supplies the corresponding direct-current light control voltage VDIM(DC) to the voltage current conversion circuit 15b. The voltage current conversion circuit 15b converts the direct-current light control voltage VDIM(DC), which is supplied from the rectifier circuit 15a, into the driving currents to be supplied to the LED chips 3, and supplies the corresponding driving currents to the first LED group D1 and the second LED group D2. Accordingly, in accordance with the conduction phase angle of the alternating-current light control voltage VDIM(AC), the driving current increases or decreases.
The control section 16 controls the voltage values of the base voltages VS applied to the bases of the transistors Q1 and Q2 while selectively turning on the transistors Q1 and Q2 in response to the alternating-current light control voltage VDIM(AC) which is supplied from the light control section 13, thereby controlling the magnitude of the driving current flowing for each LED group. Here, when the same voltages are applied to the bases of the transistors Q1 and Q2, the amounts of the driving currents flowing in the first LED group D1 and the second LED group D2 are equal. Further, when the base voltages VS are not applied to the bases of the transistors Q1 and Q2, the transistors Q1 and Q2 are not turned on. Hence, even when the driving currents are supplied from the voltage current conversion circuit 15b to the first LED group D1 and the second LED group D2, the driving currents do not flow in the first LED group D1 and the second LED group D2, and the LED chips 3 do not emit light. In the present example, when the base voltages VS are gradually increased from the state where the base voltages VS are not applied, the transistor Q1 is turned on.
A specific control method of the control section 16 of the present example is as follows. The phase angle detector 16a of the control section 16 detects the conduction phase angle, which is controlled by the light control section 13, from the light control voltage VDIM(AC) supplied from the light control section 13. Specifically, the phase angle detector 16a detects the conduction phase angle from the voltage waveform (control signal) of the light control voltage VDIM(AC). The phase angle detector 16a supplies the data signal, which represents the detected conduction phase angle, to the selection circuit 16c. The selection circuit 16c cross-checks the voltage value data, which is stored in the memory 16b, with the data signal, which represents the supplied conduction phase angle, in order to determine the voltage values of the base voltages VS applied to the bases of the transistors Q1 and Q2 in accordance with the supplied conduction phase angle. Then, the selection circuit 16c applies the base voltages VS, which have the voltage values determined through the cross-checking, to the bases of the transistors Q1 and Q2. Thereby, either one or both of the transistors Q1 and Q2 are turned on, and the magnitudes of the driving currents, which are supplied to the first LED group D1 and the second LED group D2, are controlled in accordance with the voltage values of the base voltages VS which are applied to the bases of the transistors Q1 and Q2, and the first-order light with the total luminous flux corresponding to the light control level and the color temperature corresponding to each wavelength conversion region is emitted from either one or both of the first light emitting unit U1 and the second light emitting unit U2.
Next, referring to
First, when lighting of the LED groups is started such that the darkest synthetic white light is emitted from the light emission apparatus 11 by operating the operation dial 14a, only the transistor Q1 is turned on, and the first-order light is emitted from the first light emitting unit U1. That is, at this time, the synthetic white light, which is emitted from the light emission apparatus 11, is formed of only the first-order light emitted from the first light emitting unit U1. In
When the light is controlled (that is, the light control level is lowered) such that the further bright synthetic white light is emitted by further operating the operation dial 14a, the driving current supplied to the first LED group D1 increases, and the total luminous flux of the first-order light, which is emitted from the first light emitting unit U1, increases. The increase of the total luminous flux corresponds to the curve portion 9A on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q1, is controlled by the control section 16 such that the driving current flowing in the first LED group D1 is not increased, and thus the total luminous flux of the first-order light, which is emitted from the first light emitting unit U1, is not increased. The state where the total luminous flux is not increased is defined as a full lighting state of the first light emitting unit U1. The state where the total luminous flux is not increased corresponds to the straight line portion 9B on the graph of
In the state where the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q2 is also turned on so as to start lighting of the second LED group, and thereby the first-order light is also emitted from the second light emitting unit U2. At this time, the control section 16 applies the base voltage VS to the base of the transistor Q1 so as to maintain the full lighting state of the first light emitting unit U1. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the second LED group, the base voltages VS are applied to the bases of the transistors Q1 and Q2 such that the total luminous flux of the first-order light emitted from the second light emitting unit U2 is increased while the full lighting state of the first light emitting unit U1 is maintained. The increase of the total luminous flux corresponds to the curve portion 9C on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q2, is controlled by the control section 16 such that not only the driving current flowing in the first LED group D1 but also the driving current flowing in the second LED group D2 is not increased, and thus the total luminous flux of the first-order light, which is emitted from the second light emitting unit U2, is not increased. That is, the second light emitting unit U2 also reaches the full lighting state. The full lighting state of the first light emitting unit U1 and the second light emitting unit U2 corresponds to the straight line portion 9D on the graph of
In the above-mentioned control, the transistors Q1 and Q2 are independently turned on in accordance with the light control level. Hence, it is possible to control the timing of the start of the light emission of the LED chips 3a constituting the first LED group D1 and the timing of the start of the light emission of the LED chips 3b constituting the second LED group D2, in accordance with the light control level. That is, in the light emission apparatus 11 of the present example, it is possible to independently control the timing (light start timing) of lighting the first LED group D1 and the second LED group D2 in accordance with the light control level. In other words, in the light emission apparatus 11 of the present example, the timing of starting to supply the driving current is different for each LED group. Thus, the corresponding timing of starting to supply the current is set as a current supply start light control level for each LED group in accordance with the light control level, and the LED group to be lighted on is selected on the basis of the relationship between the instruction signal (signal representing the light control level) supplied from the instruction section 14 and the corresponding current supply start light control level.
Further, when the first light emitting unit U1 reaches the full lighting state by starting to light the first LED group D1, lighting of the second LED group D2 is started. That is, as the amount of current supplied to the first LED group D1 is increased, the lighting of the second LED group D2 is started. Then, while the total luminous flux of the first-order light emitted from the second light emitting unit U2 increases, the full lighting state of the first light emitting unit U1 is maintained. Hence, after the start of the lighting of the second LED group D2, in accordance with the increase in the total luminous flux of the synthetic white light emitted from the light emission apparatus 11, the color temperature of the synthetic white light is made to be close to the color temperature of the first-order light emitted from the second light emitting unit U2 (that is, the color temperature is increased). Generally, when the total luminous flux is low, the white light (that is, the light emitted from the filament electric bulb) with a low color temperature is preferred, and when the total luminous flux is high, the white light (that is, the light emitted from the fluorescent lamp) with a high color temperature is preferred. Accordingly, in the light emission apparatus 11 and the illumination system 12 according to the present example, in accordance with the increase in the total luminous flux of the synthetic white light, the color temperature is simultaneously controlled. Thereby, it is possible to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux.
(Modified Examples of Pattern Shapes of LED Groups and Wavelength Conversion Regions)
In the above-mentioned example, the fluorescent member 5 is divided into one first wavelength conversion region P1 having a rectangular shape, and one second wavelength conversion region P2 having a rectangular shape, but the invention is not limited to this. For example, as shown in
As shown in
The four LED chips 3a arranged in one first LED group D1 may be connected in series, or may be connected in parallel. Further, the two first LED groups D1 opposed to the two first wavelength conversion regions P1 separately divided may be connected in series, or may be connected in parallel. Likewise, the four LED chips 3b arranged in one second LED group D2 may be connected in series, or may be connected in parallel. Furthermore, the two second LED groups D2 opposed to the two second wavelength conversion regions P2 separately divided may be connected in series, or may be connected in parallel.
As shown in
The four LED chips 3a arranged in the first LED group D1 may be connected in series, or may be connected in parallel. Likewise, the twelve LED chips 3b arranged in the second LED group D2 may be connected in series, or may be connected in parallel.
As shown in
The four LED chips 3a arranged in one first LED group D1 may be connected in series, or may be connected in parallel. Further, the two first LED groups D1 opposed to the two first wavelength conversion regions P1 separately divided may be connected in series, or may be connected in parallel. Likewise, the eight LED chips 3b arranged in the second LED group D2 may be connected in series, or may be connected in parallel.
A shown in
The LED chips 3a disposed in the first LED groups D1 may be connected in series, or may be connected in parallel. Likewise, the LED chips 3b disposed in the second LED groups D2 may be connected in series, or may be connected in parallel.
(Modified Example of Light Emitting Section)
Regarding the fluorescent member 5, in the present example, in either one of the first wavelength conversion region P1 and the second wavelength conversion region P2 of the fluorescent member 5, three type phosphors of the red phosphor, green phosphor, and blue phosphor are mixed, and are held in a distributed manner. However, instead of distributive holding, as shown in
Further, when the red phosphor, the green phosphor, and the yellow phosphor are mixed, distributed, and held, there is an effect that light can be satisfactorily synthesized and emitted in the respective fluorescent regions. However, there is a possibility that cascade excitation is caused by mixing of the red phosphor, the green phosphor, and the yellow phosphor in one fluorescent region. Therefore, as described above, by separately arranging the red phosphor, the green phosphor, and the yellow phosphor, it is possible to satisfactorily prevent cascade excitation. On the other hand, in terms of synthesis of the radiant light from each phosphor, in each cell region 17, although inferior to the case where the red phosphor, the green phosphor, and the yellow phosphor are mixed, distributed, and held, even in the case where the red phosphor, the green phosphor, and the yellow phosphor are separately disposed, it is possible to satisfactorily synthesize the radiant light.
That is, the directions of the plurality of cell regions 17 in the first wavelength conversion region P1 are changed into various directions and are distributed, while the directions of the plurality of cell regions 17 in the second wavelength conversion region P2 are changed into various directions and are distributed. Thereby, it is possible to satisfactorily synthesize the radiant light from each wavelength conversion region as a whole. An example of arrangement of the cell regions 17 is shown in
Note that, in the modified example, the arrangement order of the red phosphor, the green phosphor, and the yellow phosphor is made to be the same in each of the first wavelength conversion region P1 and the second wavelength conversion region P2, the direction of the first wavelength conversion region P1 and the direction of the second wavelength conversion region P2 are changed into various directions, so that the regions are distributed. However, additionally, the arrangement order of the red phosphor, the green phosphor, and the yellow phosphor of the cell region 17 may be changed.
Further, in the example and the modified example, the three types of the red phosphor, the green phosphor, and the yellow phosphor are used in each of the first wavelength conversion region P1 and the second wavelength conversion region P2. However, when using the quality (color rendering property) of the blue color, it is possible to use the LED chips emitting the near-ultraviolet light instead of the LED chips emitting blue light. In such a case, in addition to the above-mentioned phosphors, a blue phosphor, which converts the wavelength of the near-ultraviolet light into that of the blue light, is used. In this case, an appropriate wavelength range of the emission peak wavelength of the blue phosphor is normally 420 nm or more, preferably 430 nm or more, or more preferably 440 nm or more, and normally 500 nm or less, preferably 490 nm or less, more preferably 480 nm or less, further preferably 470 nm or less, or particularly preferably 460 nm or less. From this point of view, as the blue phosphor, for example, the following are preferable: (Ca, Sr, Ba)MgAl10O17:Eu; (Sr, Ca, Ba, Mg)10O4)6(Cl, F)2:Eu; (Ba, Ca, Mg, Sr)2SiO4:Eu; and (Ba, Ca, Sr)3MgSi2O8:Eu. In addition, (Ba, Sr)MgAl10O17:Eu, (Ca, Sr, Ba)10(PO4)6(Cl, F)2:Eu, and Ba3MgSi2O8:Eu are more preferable, and Sr10(PO4)6C12:Eu and BaMgAl10O17:Eu are particularly preferable.
Note that, when the LED chips emitting the near-ultraviolet light are used, adjustment of the ratio of the red phosphor, the green phosphor, and the yellow phosphor is different from adjustment thereof in the case of using the LED chips emitting the blue light.
As described above, even when the LED chips emitting the near-ultraviolet light are used, when the type, the quantitative ratio, and the quantity of the light emitting member are changed in the above-mentioned manner, it is possible to obtain target light color in the same manner as the example. Therefore, it is possible to emit the synthetic white light which is the same as that of the light emission apparatus of the example. In addition, by adjusting the number of light emitting units in a stepwise fashion, it is possible to obtain the same effects as the light emission apparatus of the example.
(Modified Example of Electric Circuit Configuration of Light Emission Apparatus)
In the above-mentioned example, the light control section 13 performs the light control by controlling the conduction phase angle of the waveform of the alternating current voltage supplied from the alternating current voltage source VAC in accordance with the instruction signal supplied from the instruction section 14. However, the light control section 13 may perform the light control by changing the own voltage value of the alternating current voltage supplied from the alternating current voltage source VAC. For example, the light control may be performed by changing the amplitude voltage value of the voltage waveform (control signal) of the alternating current voltage.
Further, when the light control is performed by changing the amplitude voltage value of the voltage waveform of the alternating current voltage, the control section 16 has a voltage detector detecting the amplitude voltage value in place of the phase angle detector 16a, and in the memory constituting the control section 16, voltage value data of the base voltage corresponding to the amplitude voltage value is recorded. In addition, in the case of the light control based on the amplitude voltage value, it is possible to obtain the same effects as the above-mentioned example.
Furthermore, the on/off control of the transistors Q1 and Q2 is not limited to the adjustment based on the voltage values of the base voltages VS mentioned above, and may be applied to adjustment based on supply times (that is, duties of the pulse widths) of the base voltages VS applied to the bases of the transistors Q1 and Q2.
In the above-mentioned example, the light control section 13 is connected to the alternating current voltage source VAC, but may be connected to the direct current voltage source VDC. In this case, the rectifier circuit 15a is not necessary.
(Effects of Present Example)
The light emission apparatus 11 of the present example includes: the wiring board 2; the plurality of LED chips 3 that are disposed on the LED chip mounting surface of the wiring board 2 so as to emit light with a predetermined wavelength range of the wavelength region ranging from the visible light region to the near-ultraviolet region, and are grouped into the plurality of LED groups; the fluorescent member 5 that is disposed at a position on the wiring board 2 corresponding to the LED chip mounting surface, and is partitioned into the plurality of wavelength conversion regions corresponding to the plurality of LED chips 3, in which the plurality of wavelength conversion regions are grouped into the plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has a different wavelength conversion characteristic, converts the wavelength of light emitted by the corresponding LED chips 3, and emits the first-order light with a different color temperature; the current supply section 15 that supplies the driving current to the LED chips 3 independently for each LED group through the wiring board 2; and the control section 16 that controls the current supplied for each LED group in response to the control signal which is input from outside. In addition, the control section 16 independently controls timing of starting to light the LED groups in accordance with the light control level. Hence, it is possible to generate the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature, and to suppress the manufacturing costs thereof.
The light emission apparatus 11 of the present example includes: the wiring board 2; the plurality of LED chips 3 that are disposed on the LED chip mounting surface of the wiring board 2 so as to emit light with a predetermined wavelength range of the wavelength region ranging from the visible light region to the near-ultraviolet region, and are grouped into the plurality of LED groups; the fluorescent member 5 that is disposed at a position on the wiring board 2 corresponding to the LED chip mounting surface, and is partitioned into the plurality of wavelength conversion regions corresponding to the plurality of LED chips 3, in which the plurality of wavelength conversion regions are grouped into the plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has a different wavelength conversion characteristic, converts the wavelength of light emitted by the corresponding LED chips 3, and emits the first-order light with a different color temperature; the current supply section 15 that supplies the driving current to the LED chips 3 independently for each LED group through the wiring board 2; and the control section 16 that controls the current supplied for each LED group in response to the control signal which is input from outside. In addition, the control section 16 sequentially lights on the LED groups, in accordance with the increase in the luminance of synthetic white light which is formed by synthesizing first-order light emitted from the plurality of wavelength conversion regions. Hence, it is possible to generate the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature, and to suppress the manufacturing costs thereof.
Furthermore, in the above-mentioned light emission apparatus 11, in accordance with the increase in the luminance of the synthetic white light, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with the lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with the higher color temperature. Hence, it is possible to increase the luminance of the synthetic white light emitted from the light emission apparatus 11, and change the color temperature of the corresponding synthetic white light appropriate for the increase in the corresponding luminance.
A further specific configuration of the light emission apparatus 11 is as follows. The plurality of LED chips and the wavelength conversion member are provided to be separated, the plurality of light emitting units are formed of the respective LED groups and the respective wavelength conversion regions corresponding to the LED groups, each of the plurality of light emitting units is integrally provided, and the light emitting units form a light emitting unit group. In this case, it is easy to treat the light emitting unit group, and thus it is possible to reduce the number of manufacturing processes and the manufacturing costs of the light emission apparatus 11.
Further, the illumination system 12 of the present example includes: the wiring board 2; the plurality of LED chips 3 that are disposed on the LED chip mounting surface of the wiring board 2 so as to emit light with the predetermined wavelength range of the wavelength region ranging from the visible light region to the near-ultraviolet region, and are grouped into the plurality of LED groups; the fluorescent member 5 that is disposed at the position on the wiring board 2 corresponding to the LED chip mounting surface, and is partitioned into the plurality of wavelength conversion regions corresponding to the plurality of LED chips 3, where the plurality of wavelength conversion regions are grouped into the plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has the different wavelength conversion characteristic, converts the wavelength of light emitted by the corresponding LED chips 3, and emits first-order light with the different color temperature; the current supply section 15 that supplies the driving current to the LED chips 3 independently for each LED group through the wiring board 2; the instruction section 14 that gives the instruction to generate synthetic white light with the desired luminance by synthesizing the first-order light; the light control section 13 that outputs the control signal to change the luminance of the synthetic white light in response to the instruction from the instruction section 14; and the control section 16 that controls the amount of the current supplied for each LED group in response to the control signal which is output from the light control section 13. In addition, the control section 16 sequentially lights on the LED groups, in accordance with the increase in the luminance of the synthetic white light. Hence, it is possible to generate the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature, and to suppress the manufacturing costs thereof.
Further, in the above-mentioned illumination system 12, in accordance with the increase in the luminance of the synthetic white light, the control section sequentially lights on the LED groups in an order from an LED group which corresponds to the wavelength conversion region emitting the first-order light with the lower color temperature, to an LED group which corresponds to the wavelength conversion region emitting the first-order light with the higher color temperature. Hence, when increasing the luminance of the synthetic white light supplied from the corresponding illumination system 12, it is possible to change the color temperature of the corresponding synthetic white light appropriate for the increase in the corresponding luminance.
Furthermore, the illumination method of the present example includes the steps of; supplying the current independently to each LED group of the plurality of LED chips 3 grouped into the plurality of LED groups so as to cause each LED group to emit light; supplying the light emitted by the LED chips 3 to the fluorescent member 5 that is partitioned into the plurality of wavelength conversion regions corresponding to the plurality of LED chips 3, in which the plurality of wavelength conversion regions are grouped into the plurality of wavelength conversion regions corresponding to the LED groups, and each wavelength conversion region has the different wavelength conversion characteristic, and emits first-order light with the different color temperature; and forming synthetic white light by synthesizing the first-order light. In addition, in the illumination method, the LED groups are sequentially lighted on by controlling the amount of the current supplied for each LED group in accordance with the increase in the luminance of the synthetic white light. Hence, it is possible to emit the light with the color temperature appropriate for the desired emission intensity by controlling the emission intensity and the color temperature while suppressing manufacturing costs of the light emission apparatus 11.
In addition, in the above-mentioned illumination method, in accordance with the increase in the luminance of the synthetic white light, the LED groups, which range from the LED group corresponding to the wavelength conversion region emitting the first-order light with the low color temperature to the LED group corresponding to the wavelength conversion region emitting the first-order light with the high color temperature, are sequentially lighted on. In this case, the synthetic white light generated by the illumination method has a color temperature appropriate for the desired luminance obtained by the light control.
Note that, in the above-mentioned example, the light emission apparatus 11 is configured to have one light emitting section 1, but the invention is not limited to this, and the light emission apparatus 11 may be configured to have a plurality of light emitting sections 1 so as to cause each light emitting section 1 to emit the synthetic white light with different color temperature. That is, by packaging each light emitting section 1, the light emission apparatus 11 may be constituted of a plurality of packages. Further, the present example described the single configuration of the light emission apparatus (illumination apparatus), but the invention may be applied to an illumination mechanism in which different light emission apparatuses (illumination step) such as an electric bulb and downlight, a heat dissipation system, and an optical lens system are added to the light emission apparatus of the present example. In such a case, it is also possible to obtain the above-mentioned effects.
In the above-mentioned first example, the first wavelength conversion region P1 and the second wavelength conversion region P2, which emit first-order light with color temperatures different from each other, constitute the fluorescent member 5. That is, from the fluorescent member 5, the two types of the first-order light with different color temperatures are emitted. However, various modifications and variations may be made without departing from the technical scope of the invention. Therefore, examples of a light emitting section 1′, a light emission apparatus 11′ and an illumination system 12′, which are configured by using a fluorescent member 5′ having a different configuration from the configuration of the fluorescent member 5 of the first example, will be described below as a second example of the present invention. Note that, the members and components the same as the first example are represented by the same reference numerals and signs, and the description thereof will be omitted.
(Configuration of Light Emitting Section)
A fluorescent member 5′ is divided into four wavelength conversion regions of a first wavelength conversion region P1′ a second wavelength conversion region P2′, a third wavelength conversion region P3′, and a fourth wavelength conversion region P4′. In the XY plane, the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ have the same planar shape and area. In accordance with the division of the fluorescent member 5′, the LED chips 3 mounted on the wiring board 2 are grouped into respective LED groups corresponding to respective positions of the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ as shown in
Accordingly, in the present example, respective combinations of the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ and the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′ corresponding thereto correspond to respective light emitting units of the present invention. That is, the first LED group D1′ and the first wavelength conversion region P1′ constitute a first light emitting unit U1′, the second LED group D2′ and the second wavelength conversion region P2′ constitute a second light emitting unit U2′, the third LED group D3′ and the third wavelength conversion region P3′ constitute a third light emitting unit U3′, and the fourth LED group D4′ and the fourth wavelength conversion region P4′ constitute a fourth light emitting unit U4′. A light emitting section 1′, in which the four light emitting units are integrated, corresponds to a light emitting unit group of the present invention. In the present example, the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′ are integrally provided, and constitute the light emitting section 1′ which is the light emitting unit group. Note that, in the description below, light, which is emitted by each of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′ and is emitted from the light emitting section 1′, is referred to as synthetic white light.
(Fluorescent Member)
As described above, the fluorescent member 5′ is divided into two of the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ corresponding to the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′. In the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′, the wavelengths of the light emitted from the LED chips 3 are converted, and various phosphors for emitting light with various wavelengths are held in a distributed manner. The used various phosphors include, in the same manner as the first example: a red phosphor which is for emitting red light by converting the wavelength of the blue light emitted by the LED chips 3; a green phosphor which is for emitting green light by converting the wavelength of the blue light emitted by the LED chips 3; and a yellow phosphor which is for emitting yellow light by converting the wavelength of the blue light emitted by the LED chips 3. Furthermore, it may be possible to use an orange phosphor which is for emitting orange light by converting the wavelength of the blue light emitted by the LED chips 3. In addition, in a similar manner to the first example, it is not necessary for the fluorescent member 5′ to hold all the above-mentioned red phosphor, green phosphor, and yellow phosphor in a distributed manner, and if the desired first-order light can be emitted from the fluorescent member 5′, one type or two or more types of phosphors may be selected from the above-mentioned phosphors. For example, the fluorescent member 5′ may hold the red phosphor and the green phosphor in a distributed manner, and may not hold the yellow phosphor in a distributed manner. The other specific composition, structure, and the like of the phosphors are the same as those of the first example.
Further, the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ are different in the mass and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor. Accordingly, the ratios of the red light, the green light, and the yellow light, which are emitted from each wavelength conversion region, to the blue light, which is emitted without the wavelength conversion, are different from each other. Hence, there are differences among color temperatures of: the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the first wavelength conversion region P1′; the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the second wavelength conversion region P2′; the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the third wavelength conversion region P3′; and the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the fourth wavelength conversion region P4′.
In a similar manner to the first example, the numbers of phosphors, which are held in a distributed manner in the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′, may be different from each other. In such a case, the color temperatures of the first-order light respectively emitted from the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ are made to be different from each other.
Next, referring to
Note that, the y value of the CIE (1931) XYZ color coordinate system at any chromaticity point of the first-order light, which is emitted from each of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′, is preferably equal to or less than 0.65. When the y value is greater than 0.65, the takeoff efficiency of the visible light of each light emitting unit deteriorates, and it is difficult for the overall light emission apparatus to efficiently emit light. On the other hand, when LED chips emitting near-ultraviolet light are used instead of the LED chips 3 emitting the blue light, there is no trouble even if the y value is greater than 0.65.
By determining the mixture ratio of the phosphors in each wavelength conversion region in the above-mentioned method, it is possible to set the magnitudes of the color temperatures of the first-order light emitted from the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′ in order of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′ and the fourth light emitting unit U4′.
In the present example, as the red phosphor, (Sr, Ca)1AlSiN3:Eu is used, as the green phosphor, Ca3(Sc, Mg)2Si3O12:Ce is used, and as the yellow phosphor, Y3Al5O12:Ce is used. Further, as shown in
Furthermore, the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ have different film thicknesses. Specifically, as shown in
(Electric Circuit Configuration of Light Emission Apparatus)
As described above, in the light emission apparatus of the present example, the color temperatures of the first-order light, which are respectively emitted from the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′, are set to be different from each other, and the synthetic white light, which is generated by synthesizing the first-order light emitted from the light emitting units, is emitted from the light emission apparatus. Accordingly, in the light emission apparatus of the present example, by changing the total luminous flux (that is, emission intensity or luminance) of the first-order light emitted from each of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′, the total luminous flux of the synthetic white light emitted from the light emission apparatus is adjusted, and the color temperature of the synthetic white light is changed in accordance with the corresponding total luminous flux of the synthetic white light so as to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux mentioned above. The configurations of the light emitting section 1′ and the current supply section 15′, which are circuit configuration portions different from those of the first example, will be described below with reference to
The light emitting section 1′ has the LED chips 3a′ of the first LED group D1′, the LED chips 3b′ of the second LED group D2′, the LED chips 3c′ of the third LED group D3′, and the LED chips 3d′ of the fourth LED group D4′. In specific configurations of the first LED group D1′ and the second LED group D2′, the four LED chips 3a′ of the first LED group D1′ are connected to one another in series such that the polarities thereof are the same, and the four LED chips 3b′ of the second LED group D2′ are also connected to one another in series such that the polarities thereof are the same. Likewise, in specific configurations of the third LED group D3′ and the fourth LED group D4′, the four LED chips 3c′ of the third LED group D3′ are connected to one another in series such that the polarities thereof are the same, and the four LED chips 3d′ of the fourth LED group D4′ are also connected to one another in series such that the polarities thereof are the same. Further, the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′ are connected in parallel through a switch circuit 15c′ to be described later. Note that, the connection form of the LED chips 3 in the same LED group is not limited to serial connection, and may be, for example, parallel connection in which the LED chips 3 are connected to one another in parallel such that the polarities thereof are the same.
The current supply section 15′ is formed of the rectifier circuit 15a, the voltage current conversion circuit 15b, and the switch circuit 15c′. The rectifier circuit 15a and the voltage current conversion circuit 15b have the same configuration as the first example, and thus the description thereof will be omitted. The switch circuit 15c′ includes transistors Q1, Q2, Q3, and Q4. Each collector of the transistors Q1, Q2, Q3, and Q4 is connected to a terminal closest to a cathode of each of the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′, each emitter of the transistors Q1, Q2, Q3, and Q4 is connected to the voltage current conversion circuit 15b, and each base of the transistors Q1, Q2, Q3, and Q4 is connected to the control section 16.
In the illumination system 12′ of the present example, due to the configuration and the connection relationship of the light control section 13, the instruction section 14, and the current supply section 15′ mentioned above, it is possible to adjust the amount of driving current (the amount of supply current), which is supplied to the LED chips 3, only by rotating the operation dial 14a. In addition, by adjusting the amount of supply current supplied to the light emitting section 1′, it is possible to emit (that is, control) the synthetic white light with the desired total luminous flux from the light emission apparatus 11′.
(Control of Light Emitting Section)
When a user of the light emission apparatus 11′ operates the operation dial 14a, the main body 14b of the instruction section 14 detects the position of the operation dial 14a, and supplies the instruction signal (signal representing the light control level) based on the detected position of the operation dial 14a to the light control section 13. The light control section 13 controls the conduction phase angle of the waveform of the alternating current voltage, which is supplied from the alternating current voltage source VAC, on the basis of the instruction signal supplied from the instruction section 14, thereby generating the alternating-current light control voltage VDIM(AC). In a specific control method, the light control section 13 inputs a trigger pulse with an arbitrary phase difference relative to the zero cross point of the sinusoidal waveform of the alternating current supplied from the alternating current voltage source so as to control the conduction phase angle. Accordingly, when the supplied instruction signal is changed, the light control section 13 controls the conduction phase angle by changing the phase difference of the trigger pulse in accordance with the change.
The rectifier circuit 15a of the current supply section 15′ converts the alternating-current light control voltage VDIM(AC), which is supplied from the light control section 13, into the direct-current light control voltage VDIM(DC), and supplies the corresponding direct-current light control voltage VDIM(DC) to the voltage current conversion circuit 15b. The voltage current conversion circuit 15b converts the direct-current light control voltage VDIM(DC), which is supplied from the rectifier circuit 15a, into the driving currents to be supplied to the LED chips 3, and supplies the corresponding driving currents to the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′.
The control section 16 controls the voltage values of the base voltages VS applied to the bases of the transistors Q1, Q2, Q3, and Q4 while selectively turning on the transistors Q1, Q2, Q3, and Q4 in response to the alternating-current light control voltage VDIM(AC) which is supplied from the light control section 13, thereby controlling the magnitude of the driving current flowing for each LED group. Here, when the base voltages VS with the same voltage values are applied to the bases of the transistors Q1, Q2, Q3, and Q4, the amounts of the driving currents flowing in the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′ are equal. Further, when the base voltages VS are not applied to the bases of the transistors Q1, Q2, Q3, and Q4, the transistors Q1, Q2, Q3, and Q4 are not turned on. Hence, even when the driving currents are supplied from the voltage current conversion circuit 15b to the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′, the driving currents do not flow in the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′, and the LED chips 3 do not emit light. In the present example, when the base voltages VS are gradually increased from the state where the base voltages VS are not applied, the transistors are turned on in order of the transistors Q1, Q2, Q3, and Q4.
A specific control method of the control section 16 of the present example is as follows. Note that, in the memory 16b of the control section 16, the voltage value data of the base voltages applied to the bases of the transistors Q1, Q2, Q3, and Q4 is recorded to correspond to the conduction phase angles controlled by the light control section 13. The phase angle detector 16a of the control section 16 detects the conduction phase angle, which is controlled by the light control section 13, from the alternating-current light control voltage VDIM(AC) supplied from the light control section 13. Specifically, the phase angle detector 16a detects the conduction phase angle from the voltage waveform (control signal) of the light control voltage VDIM(AC). The phase angle detector 16a supplies the data signal, which represents the detected conduction phase angle, to the selection circuit 16c. The selection circuit 16c cross-checks the voltage value data, which is stored in the memory 16b and relates to the transistors Q1, Q2, Q3, and Q4, with the data signal, which represents the supplied conduction phase angle, in order to determine the voltage values of the base voltages VS applied to the bases of the transistors Q1, Q2, Q3, and Q4 in accordance with the supplied conduction phase angle. Then, the selection circuit 16c applies the base voltages VS, which have the voltage values determined through the cross-checking, to the bases of the transistors Q1, Q2, Q3, and Q4. Thereby, at least one of the transistors Q1, Q2, Q3, and Q4 are turned on, and the magnitudes of the driving currents, which are supplied to the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′, are controlled in accordance with the voltage values of the base voltages VS which are applied to the bases of the transistors Q1, Q2, Q3, and Q4, and the synthetic white light with the total luminous flux corresponding to the light control level and the color temperature corresponding to each wavelength conversion region is emitted from at least one of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′.
Next, referring to
First, when lighting of the LED groups is started such that the darkest synthetic white light is emitted from the light emission apparatus 11′ by operating the operation dial 14a, only the transistor Q1 is turned on, and the first-order light is emitted from the first light emitting unit U1′. That is, at this time, the synthetic white light, which is emitted from the light emission apparatus 11′, is formed of only the first-order light emitted from the first light emitting unit U1′. In
When the light is controlled (that is, the light control level is lowered) such that the further bright synthetic white light is emitted by further operating the operation dial 14a, the driving current supplied to the first LED group D1′ increases, and the total luminous flux of the first-order light, which is emitted from the first light emitting unit U1′, increases. The increase of the total luminous flux corresponds to the curve portion 24A on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q1, is controlled by the control section 16 such that the driving current flowing in the first LED group D1′ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the first light emitting unit U1′, is not increased. The state where the total luminous flux is not increased is defined as a full lighting state of the first light emitting unit U1′. The state where the total luminous flux is not increased corresponds to the straight line portion 24B on the graph of
In the state where the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q2 is also turned on so as to start lighting of the second LED group D2′, and thereby the first-order light is also emitted from the second light emitting unit U2′. At this time, the control section 16 applies the base voltage VS to the base of the transistor Q1 so as to maintain the full lighting state of the first light emitting unit U1′. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the second LED group D2′, the base voltages VS are applied to the bases of the transistors Q1 and Q2 such that the total luminous flux of the first-order light emitted from the second light emitting unit U2′ is increased while the full lighting state of the first light emitting unit U1′ is maintained. The increase of the total luminous flux corresponds to the curve portion 24C on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q2, is controlled by the control section 16 such that not only the driving current flowing in the first LED group D1′ but also the driving current flowing in the second LED group D2′ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the second light emitting unit U2′, is not increased. That is, the second light emitting unit U2′ also reaches the full lighting state. The full lighting states of the first light emitting unit U1′ and the second light emitting unit U2′ correspond to the straight line portion 24D on the graph of
In the state where the second light emitting unit U2′ reaches the full lighting state and thereby the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q3 is also turned on so as to start lighting of the third LED group D3′, and thereby the first-order light is also emitted from the third light emitting unit U3′. At this time, the control section 16 applies the base voltages VS to the bases of the transistors Q1 and Q2 so as to maintain the full lighting states of the first light emitting unit U1′ and the second light emitting unit U2′. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the third LED group D3′, the base voltages VS are applied to the bases of the transistors Q1, Q2, and Q3 such that the total luminous flux of the first-order light emitted from the third light emitting unit U3′ is increased while the full lighting states of the first light emitting unit U1′ and the second light emitting unit U2′ are maintained. The increase of the total luminous flux corresponds to the curve portion 24E on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q3, is controlled by the control section 16 such that not only the driving currents flowing in the first LED group D1′ and the second LED group D2′ but also the driving current flowing in the third LED group D3′ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the third light emitting unit U3′, is not increased. That is, the third light emitting unit U3′ also reaches the full lighting state. The full lighting states of the first light emitting unit U1′, the second light emitting unit U2′, and the third light emitting unit U3′ correspond to the straight line portion 24F on the graph of
In the state where the third light emitting unit U3′ reaches the full lighting state and thereby the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q4 is also turned on so as to start lighting of the fourth LED group D4′, and thereby the first-order light is also emitted from the fourth light emitting unit U4′. At this time, the control section 16 applies the base voltages VS to the bases of the transistors Q1, Q2, and Q3 so as to maintain the full lighting states of the first light emitting unit U1′, the second light emitting unit U2′, and the third light emitting unit U3′. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the fourth LED group D4′, the base voltages VS are applied to the bases of the transistors Q1, Q2, Q3, and Q4 such that the total luminous flux of the first-order light emitted from the fourth light emitting unit U4′ is increased while the full lighting states of the first light emitting unit U1′, the second light emitting unit U2′, and the third light emitting unit U3′ are maintained. The increase of the total luminous flux corresponds to the curve portion 24G on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q4, is controlled by the control section 16 such that not only the driving currents flowing in the first LED group D1′, the second LED group D2′, and the third LED group D3′ but also the driving current flowing in the fourth LED group D4′ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the fourth light emitting unit U4′, is not increased. That is, the fourth light emitting unit U4′ also reaches the full lighting state. The full lighting states of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′, and the fourth light emitting unit U4′ correspond to the straight line portion 24H on the graph of
In the above-mentioned control, the transistors Q1, Q2, Q3, and Q4 are independently turned on in accordance with the light control level. Hence, it is possible to control the timing of the start of the light emission of the LED chips 3a′, the timing of the start of the light emission of the LED chips 3b′, the timing of the start of the light emission of the LED chips 3c′, and the timing of the start of the light emission of the LED chips 3d′, in accordance with the light control level. That is, in the light emission apparatus 11′ of the present example, it is possible to independently control the timing (light start timing) of lighting the first LED group D1′, the second LED group D2′, the third LED group D3′, and the fourth LED group D4′ in accordance with the light control level. In other words, in the light emission apparatus 11′ of the present example, the timing of starting to supply the driving current is different for each LED group. Thus, the corresponding timing of starting to supply the current is set as a current supply start light control level for each LED group in accordance with the light control level, and the LED group to be lighted on is selected on the basis of the relationship between the instruction signal (signal representing the light control level) supplied from the instruction section 14 and the corresponding current supply start light control level.
Further, when the first light emitting unit U1′ reaches the full lighting state by starting to light the first LED group D1′, lighting of the second LED group D2′ is started. Then, while the total luminous flux of the first-order light emitted from the second light emitting unit U2′ increases, the full lighting state of the first light emitting unit U1′ is maintained. Hence, after the start of the lighting of the second LED group D2′, in accordance with the increase in the total luminous flux of the synthetic white light emitted from the light emission apparatus 11′, the color temperature of the synthetic white light also increases. Likewise, while lighting of the third LED group D3′ is started and then the total luminous flux of the first-order light emitted from the third light emitting unit U3′ increases, the full lighting states of the first light emitting unit U1′ and the second light emitting unit U2′ are maintained. In addition, while lighting of the fourth LED group D4′ is started and then the total luminous flux of the first-order light emitted from the fourth light emitting unit U4′ increases, the full lighting states of the first light emitting unit U1′, the second light emitting unit U2′, the third light emitting unit U3′ are maintained. That is, as the total amount of currents supplied to the plurality of LED groups increases, the respective LED groups are sequentially lighted on. Hence, after the start of the lighting of the third LED group D3′ and after the start of the lighting of the fourth LED group D4′, in accordance with the increase in the total luminous flux of the synthetic white light emitted from the light emission apparatus 11′, the color temperature of the synthetic white light also increases. Generally, when the total luminous flux is low, the white light (that is, the light emitted from the filament electric bulb) with a low color temperature is preferred, and when the total luminous flux is high, the white light (that is, the light emitted from the fluorescent lamp) with a high color temperature is preferred. Accordingly, in the light emission apparatus 11′ and the illumination system 12′ according to the present example, in accordance with the increase in the total luminous flux of the synthetic white light, the color temperature is simultaneously controlled. Thereby, it is possible to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux.
(Modified Examples of Pattern Shapes of LED Groups and Wavelength Conversion Regions)
In the above-mentioned example, the fluorescent member 5′ is divided into four regions of the first wavelength conversion region P1′, the second wavelength conversion region P2′, the third wavelength conversion region P3′, and the fourth wavelength conversion region P4′ which have square shapes, but the invention is not limited to this. For example, as shown in
As shown in
The four LED chips 3a′ arranged in the first LED group D1′ and the four LED chips 3b′ arranged in the second LED group D2′ may be connected in series, or may be connected in parallel. Likewise, four LED chips 3c′ arranged in one third LED group D3′ and the four LED chips 3d′ arranged in the fourth LED group D4′ may be connected in series, or may be connected in parallel.
(Effects of the Present Example)
Compared with the light emission apparatus 11 and the illumination system 12 of the first example, the light emission apparatus 11′ and the illumination system 12′ according to the present example is different in the number of LED groups and the number of wavelength conversion regions, but has the same basic structure. Hence, even in the light emission apparatus 11′, the illumination system 12′, and the illumination method according to the present example, it is possible to obtain the same effect as the first example. Further, compared with the light emission apparatus 11 and the illumination system 12 of the first example, in the light emission apparatus 11′ and the illumination system 12′ according to the present example, the number of LED groups and the number of wavelength conversion regions are large. Hence, it is possible to more accurately control the color temperature relative to the change in the luminance of the synthetic white light.
In the above-mentioned first example, the first wavelength conversion region P1 and the second wavelength conversion region P2, which emit first-order light with color temperatures different from each other, constitute the fluorescent member 5. That is, from the fluorescent member 5, the two types of the first-order light with different color temperatures are emitted. However, various modifications and variations may be made without departing from the technical scope of the invention. Therefore, examples of a light emitting section 1″, a light emission apparatus 11″ and an illumination system 12″, which are configured by using a fluorescent member 5″ having a different configuration from the configuration of the fluorescent member 5 of the first example, will be described below as a third example of the present invention. Note that, the members and components the same as the first example are represented by the same reference numerals and signs, and the description thereof will be omitted.
(Configuration of Light Emitting Section)
A fluorescent member 5″ is divided into five wavelength conversion regions of a first wavelength conversion region P1″ a second wavelength conversion region P2″, a third wavelength conversion region P3″, a fourth wavelength conversion region P4″, and a fifth wavelength conversion region P5″. Specifically, the first wavelength conversion region P1″ and the second wavelength conversion region P2″ having square shapes are disposed two corner portions of the fluorescent member 5″. The third wavelength conversion region P3″ and the fourth wavelength conversion region P4″ having rectangular shapes are disposed to extend in the X directions from the terminal of the fluorescent member 5″ toward the first wavelength conversion region P1″ and the second wavelength conversion region P2″. The fifth wavelength conversion region P5″ having a rectangular shape is disposed to be interposed in the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″ and the fourth wavelength conversion region P4″ and to extend in the X direction. Further, in the XY plane, the first wavelength conversion region P1″ and the second wavelength conversion region P2″ have the same planar shape and area. In addition, the third wavelength conversion region P3″ and the fourth wavelength conversion region P4″ have the same planar shape and area.
In accordance with the division of the fluorescent member 5″, the LED chips 3 mounted on the wiring board 2 are grouped into respective LED groups corresponding to respective positions of the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″ as shown in
In the description below, in order to distinguish the LED chips 3 for each wavelength conversion region, a″, b″, c″, d″ and e″ are respectively attached to the tail end of the reference sign thereof so as to correspond to the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″. Therefore, the four LED chips 3a″ positioned to correspond to the first wavelength conversion region P1″ constitute a first LED group D1″, the four LED chips 3b″ positioned to correspond to a second wavelength conversion region P2″ constitute a second LED group D2″, the eight LED chips 3c″ positioned to correspond to the third wavelength conversion region P3″ constitute a third LED group D3″, the eight LED chips 3d″ positioned to correspond to the fourth wavelength conversion region P4″ constitute a fourth LED group D4″, and the 16 LED chips 3e″ positioned to correspond to the fifth wavelength conversion region P5″ constitute a fifth LED group D5″.
Accordingly, in the present example, respective combinations of the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″ and the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″ corresponding thereto correspond to respective light emitting units of the present invention. That is, the first LED group D1″ and the first wavelength conversion region P1″ constitute a first light emitting unit U1″, the second LED group D2″ and the second wavelength conversion region P2″ constitute a second light emitting unit U2″, the third LED group D3″ and the third wavelength conversion region P3″ constitute a third light emitting unit U3″, the fourth LED group D4″ and the fourth wavelength conversion region P4″ constitute a fourth light emitting unit U4″, and the fifth LED group D5″ and the fifth wavelength conversion region P5″ constitute a fifth light emitting unit U5″. A light emitting section 1″, in which the five light emitting units are integrated, corresponds to a light emitting unit group of the present invention. In the present example, the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″ are integrally provided, and constitute the light emitting section 1″ which is the light emitting unit group. Note that, in the description below, light, which is emitted by each of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″ and is emitted from the light emitting section 1″, is referred to as synthetic white light.
(Fluorescent Member)
As described above, the fluorescent member 5″ is divided into four regions of the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″ corresponding to the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″. In the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″, the wavelengths of the light emitted from the LED chips 3 are converted, and various phosphors for emitting light with various wavelengths are held in a distributed manner. The used various phosphors include, in the same manner as the first example: a red phosphor which is for emitting red light by converting the wavelength of the blue light emitted by the LED chips 3; a green phosphor which is for emitting green light by converting the wavelength of the blue light emitted by the LED chips 3; and a yellow phosphor which is for emitting yellow light by converting the wavelength of the blue light emitted by the LED chips 3. Furthermore, it may be possible to use an orange phosphor which is for emitting orange light by converting the wavelength of the blue light emitted by the LED chips 3. In addition, in a similar manner to the first example, it is not necessary for the fluorescent member 5″ all the above-mentioned red phosphor, green phosphor, and yellow phosphor in a distributed manner, and if the desired first-order light can be emitted from the fluorescent member 5″, one type or two or more types of phosphors may be selected from the above-mentioned phosphors. For example, the fluorescent member 5″ may hold the red phosphor and the green phosphor in a distributed manner, and may not hold the yellow phosphor in a distributed manner. The other specific composition, structure, and the like of the phosphors are the same as those of the first example.
Further, the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″ are different in the mass and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor. Accordingly, the ratios of the red light, the green light, and the yellow light, which are emitted from each wavelength conversion region, to the blue light, which is emitted without the wavelength conversion, are different from each other. Hence, there are differences among color temperatures of: the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the first wavelength conversion region P1″; the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the second wavelength conversion region P2″; the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the third wavelength conversion region P3″; the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the fourth wavelength conversion region P4″; and the white light, which is the first-order light formed by synthesizing the red light, green light, yellow light, and blue light emitted from the fifth wavelength conversion region P5″.
In a similar manner to the first example, the numbers of phosphors, which are held in a distributed manner in the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″, may be different from each other. In such a case, the color temperatures of the first-order light respectively emitted from the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″ are made to be different from each other.
Next, referring to
By determining the mixture ratio of the phosphors in each wavelength conversion region in the above-mentioned method, it is possible to set the magnitudes of the color temperatures of the first-order light emitted from the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″ in order of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″.
In the present example, as the red phosphor, (Sr, Ca)1AlSiN3:Eu is used, as the green phosphor, Ca3(Sc, Mg)2Si3O12:Ce is used, and as the yellow phosphor, Y3Al5O12:Ce is used. Further, as shown in
Furthermore, the first wavelength conversion region P1″, the second wavelength conversion region P2″, the third wavelength conversion region P3″, the fourth wavelength conversion region P4″, and the fifth wavelength conversion region P5″ have different film thicknesses. Specifically, as shown in
(Electric Circuit Configuration of Light Emission Apparatus)
As described above, in the light emission apparatus of the present example, the color temperatures of the first-order light, which are respectively emitted from the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″, are set to be different from each other, and the synthetic white light, which is generated by synthesizing the first-order light emitted from the light emitting units, is emitted from the light emission apparatus. Accordingly, in the light emission apparatus of the present example, by changing the total luminous flux (that is, emission intensity or luminance) of the first-order light emitted from each of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″, the total luminous flux of the synthetic white light emitted from the light emission apparatus is adjusted, and the color temperature of the synthetic white light is changed in accordance with the corresponding total luminous flux of the synthetic white light so as to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux mentioned above. The configurations of the light emitting section 1″ and the current supply section 15″, which are circuit configuration portions different from those of the first example, will be described below with reference to
The light emitting section 1″ has the LED chips 3a″ of the first LED group D1″, the LED chips 3b″ of the second LED group D2″, the LED chips 3c″ of the third LED group D3″, the LED chips 3d″ of the fourth LED group D4″, and the LED chips 3e″ of the fifth LED group D5″. In specific configurations of the first LED group D1″ and the second LED group D2″, the four LED chips 3a″ of the first LED group D1″ are connected to one another in series such that the polarities thereof are the same, and the four LED chips 3b″ of the second LED group D2″ are also connected to one another in series such that the polarities thereof are the same. Likewise, in specific configurations of the third LED group D3″ and the fourth LED group D4″, the eight LED chips 3c″ of the third LED group D3″ are connected to one another in series such that the polarities thereof are the same, and the eight LED chips 3d″ of the fourth LED group D4″ are also connected to one another in series such that the polarities thereof are the same. Furthermore, in specific configurations of the fifth LED group D5″, the 16 LED chips 3e″ of the fifth LED group D5″ are also connected to one another in series such that the polarities thereof are the same. Further, the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″ are connected in parallel through a switch circuit 15c″ to be described later. Note that, the connection form of the LED chips 3 in the same LED group is not limited to serial connection, and may be, for example, parallel connection in which the LED chips 3 are connected to one another in parallel such that the polarities thereof are the same.
The current supply section 15″ is formed of the rectifier circuit 15a, the voltage current conversion circuit 15b, and the switch circuit 15c″. The rectifier circuit 15a and the voltage current conversion circuit 15b have the same configuration as the first example, and thus the description thereof will be omitted. The switch circuit 15c″ includes transistors Q1, Q2, Q3, Q4, and Q5. Each collector of the transistors Q1, Q2, Q3, Q4, and Q5 is connected to a terminal closest to a cathode of each of the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″, each emitter of the transistors Q1, Q2, Q3, Q4, and Q5 is connected to the voltage current conversion circuit 15b, and each base of the transistors Q1, Q2, Q3, Q4, and Q5 is connected to the control section 16.
In the illumination system 12″ of the present example, due to the configuration and the connection relationship of the light control section 13, the instruction section 14, and the current supply section 15″ mentioned above, it is possible to adjust the amount of driving current (the amount of supply current), which is supplied to the LED chips 3, only by rotating the operation dial 14a. In addition, by adjusting the amount of supply current supplied to the light emitting section 1″, it is possible to emit (that is, control) the synthetic white light with the desired total luminous flux from the light emission apparatus 11″.
(Control of Light Emitting Section)
When a user of the light emission apparatus 11″ operates the operation dial 14a, the main body 14b of the instruction section 14 detects the position of the operation dial 14a, and supplies the instruction signal (signal representing the light control level) based on the detected position of the operation dial 14a to the light control section 13. The light control section 13 controls the conduction phase angle of the waveform of the alternating current voltage, which is supplied from the alternating current voltage source VAC, on the basis of the instruction signal supplied from the instruction section 14, thereby generating the alternating-current light control voltage VDIM(AC). In a specific control method, the light control section 13 inputs a trigger pulse with an arbitrary phase difference relative to the zero cross point of the sinusoidal waveform of the alternating current supplied from the alternating current voltage source so as to control the conduction phase angle. Accordingly, when the supplied instruction signal is changed, the light control section 13 controls the conduction phase angle by changing the phase difference of the trigger pulse in accordance with the change.
The rectifier circuit 15a of the current supply section 15″ converts the alternating-current light control voltage VDIM(AC), which is supplied from the light control section 13, into the direct-current light control voltage VDIM(DC), and supplies the corresponding direct-current light control voltage VDIM(DC) to the voltage current conversion circuit 15b. The voltage current conversion circuit 15b converts the direct-current light control voltage VDIM(DC), which is supplied from the rectifier circuit 15a, into the driving currents to be supplied to the LED chips 3, and supplies the corresponding driving currents to the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″.
The control section 16 controls the voltage values of the base voltages VS applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5 while selectively turning on the transistors Q1, Q2, Q3, Q4, and Q5 in response to the alternating-current light control voltage VDIM(AC) which is supplied from the light control section 13, thereby controlling the magnitude of the driving current flowing for each LED group. Here, when the same voltages are applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5, the amounts of the driving currents flowing in the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″ are equal. Further, when the base voltages VS are not applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5, the transistors Q1, Q2, Q3, Q4, and Q5 are not turned on. Hence, even when the driving currents are supplied from the voltage current conversion circuit 15b to the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″, the driving currents do not flow in the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″, and the LED chips 3 do not emit light.
A specific control method of the control section 16 of the present example is as follows. Note that, in the memory 16b of the control section 16, the voltage value data of the base voltages applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5 is recorded to correspond to the conduction phase angles controlled by the light control section 13. The phase angle detector 16a of the control section 16 detects the conduction phase angle, which is controlled by the light control section 13, from the alternating-current light control voltage VDIM(AC) supplied from the light control section 13. Specifically, the phase angle detector 16a detects the conduction phase angle from the voltage waveform (control signal) of the light control voltage VDIM(AC). The phase angle detector 16a supplies the data signal, which represents the detected conduction phase angle, to the selection circuit 16c. The selection circuit 16c cross-checks the voltage value data, which is stored in the memory 16b and relates to the transistors Q1, Q2, Q3, Q4, and Q5, with the data signal, which represents the supplied conduction phase angle, in order to determine the voltage values of the base voltages VS applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5 in accordance with the supplied conduction phase angle. Then, the selection circuit 16c applies the base voltages VS, which have the voltage values determined through the cross-checking, to the bases of the transistors Q1, Q2, Q3, Q4, and Q5. Thereby, at least one of the transistors Q1, Q2, Q3, Q4, and Q5 are turned on, and the magnitudes of the driving currents, which are supplied to the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″, are controlled in accordance with the voltage values of the base voltages VS which are applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5, and the synthetic white light with the total luminous flux corresponding to the light control level and the color temperature corresponding to each wavelength conversion region is emitted from at least one of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″. In the present example, when the base voltages VS are gradually increased from the state where the base voltages VS are not applied, the transistors are turned on in order of the transistors Q1, Q2, Q3, Q4, and Q5.
Next, referring to
First, when lighting of the LED groups is started such that the darkest synthetic white light is emitted from the light emission apparatus 11″ by operating the operation dial 14a, only the transistor Q1 is turned on, and the first-order light is emitted from the first light emitting unit U1″. That is, at this time, the synthetic white light, which is emitted from the light emission apparatus 11″, is formed of only the first-order light emitted from the first light emitting unit U1″. In
When the light is controlled (that is, the light control level is lowered) such that the further bright synthetic white light is emitted by further operating the operation dial 14a, the driving current supplied to the first LED group D1″ increases, and the total luminous flux of the first-order light, which is emitted from the first light emitting unit U1″, increases. The increase of the total luminous flux corresponds to the curve portion 36A on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q1, is controlled by the control section 16 such that the driving current flowing in the first LED group D1″ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the first light emitting unit U1″, is not increased. The state where the total luminous flux is not increased is defined as a full lighting state of the first light emitting unit U1″. The state where the total luminous flux is not increased corresponds to the straight line portion 36B on the graph of
In the state where the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q2 is also turned on so as to start lighting of the second LED group D2″, and thereby the first-order light is also emitted from the second light emitting unit U2″. At this time, the control section 16 applies the base voltage VS to the base of the transistor Q1 so as to maintain the full lighting state of the first light emitting unit U1″. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the second LED group D2″, the base voltages VS are applied to the bases of the transistors Q1 and Q2 such that the total luminous flux of the first-order light emitted from the second light emitting unit U2″ is increased while the full lighting state of the first light emitting unit U1″ is maintained. The increase of the total luminous flux corresponds to the curve portion 36C on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q2, is controlled by the control section 16 such that not only the driving current flowing in the first LED group D1″ but also the driving current flowing in the second LED group D2″ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the second light emitting unit U2″, is not increased. That is, the second light emitting unit U2″ also reaches the full lighting state. The full lighting states of the first light emitting unit U1″ and the second light emitting unit U2″ correspond to the straight line portion 36D on the graph of
In the state where the second light emitting unit U2″ reaches the full lighting state and thereby the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q3 is also turned on so as to start lighting of the third LED group D3″, and thereby the first-order light is also emitted from the third light emitting unit U3″. At this time, the control section 16 applies the base voltages VS to the bases of the transistors Q1 and Q2 so as to maintain the full lighting states of the first light emitting unit U1″ and the second light emitting unit U2″. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the third LED group D3″, the base voltages VS are applied to the bases of the transistors Q1, Q2, and Q3 such that the total luminous flux of the first-order light emitted from the third light emitting unit U3″ is increased while the full lighting states of the first light emitting unit U1″ and the second light emitting unit U2″ are maintained. The increase of the total luminous flux corresponds to the curve portion 36E on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q3, is controlled by the control section 16 such that not only the driving currents flowing in the first LED group D1″ and the second LED group D2″ but also the driving current flowing in the third LED group D3″ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the third light emitting unit U3″, is not increased. That is, the third light emitting unit U3″ also reaches the full lighting state. The full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, and the third light emitting unit U3″ correspond to the straight line portion 36F on the graph of
In the state where the third light emitting unit U3″ reaches the full lighting state and thereby the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q4 is also turned on so as to start lighting of the fourth LED group D4″, and thereby the first-order light is also emitted from the fourth light emitting unit U4″. At this time, the control section 16 applies the base voltages VS to the bases of the transistors Q1, Q2, and Q3 so as to maintain the full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, and the third light emitting unit U3″. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the fourth LED group D4″, the base voltages VS are applied to the bases of the transistors Q1, Q2, Q3, and Q4 such that the total luminous flux of the first-order light emitted from the fourth light emitting unit U4″ is increased while the full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, and the third light emitting unit U3″ are maintained. The increase of the total luminous flux corresponds to the curve portion 36G on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q4, is controlled by the control section 16 such that not only the driving currents flowing in the first LED group D1″, the second LED group D2″, and the third LED group D3″ but also the driving current flowing in the fourth LED group D4″ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the fourth light emitting unit U4″, is not increased. That is, the fourth light emitting unit U4″ also reaches the full lighting state. The full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, and the fourth light emitting unit U4″ correspond to the straight line portion 36H on the graph of
In the state where the fourth light emitting unit U4″ reaches the full lighting state and thereby the increase in the total luminous flux of the synthetic white light mentioned above is suppressed, when the light control level is further lowered by further operating the operation dial 14a, the transistor Q5 is also turned on so as to start lighting of the fifth LED group D5″, and thereby the first-order light is also emitted from the fifth light emitting unit U5″. At this time, the control section 16 applies the base voltages VS to the bases of the transistors Q1, Q2, Q3, and Q4 so as to maintain the full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, and the fourth light emitting unit U4″. In
When the light control level is further lowered by further operating the operation dial 14a from the start of lighting of the fifth LED group D5″, the base voltages VS are applied to the bases of the transistors Q1, Q2, Q3, Q4, and Q5 such that the total luminous flux of the first-order light emitted from the fifth light emitting unit U5″ is increased while the full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, and the fourth light emitting unit U4″ are maintained. The increase of the total luminous flux corresponds to the curve portion 36I on the graph of
When the light control level is further lowered by further operating the operation dial 14a, the voltage value of the base voltage VS, which is applied to the base of the transistor Q5, is controlled by the control section 16 such that not only the driving currents flowing in the first LED group D1″, the second LED group D2″, the third LED group D3″, and the fourth LED group D4″ but also the driving current flowing in the fifth LED group D5″ is not increased, and thus the total luminous flux of the first-order light, which is emitted from the fifth light emitting unit U5″, is not increased. That is, the fifth light emitting unit U5″ also reaches the full lighting state. The full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, the fourth light emitting unit U4″, and the fifth light emitting unit U5″ correspond to the straight line portion 36J on the graph of
Further,
In the above-mentioned control, the transistors Q1, Q2, Q3, Q4, and Q5 are independently turned on in accordance with the light control level. Hence, it is possible to control the timing of the start of the light emission of the LED chips 3a″, the timing of the start of the light emission of the LED chips 3b″, the timing of the start of the light emission of the LED chips 3c″, the timing of the start of the light emission of the LED chips 3d″, and the timing of the start of the light emission of the LED chips 3e″, in accordance with the light control level. That is, in the light emission apparatus 11″ of the present example, it is possible to independently control the timing (light start timing) of lighting the first LED group D1″, the second LED group D2″, the third LED group D3″, the fourth LED group D4″, and the fifth LED group D5″ in accordance with the light control level. In other words, in the light emission apparatus 11″ of the present example, the timing of starting to supply the driving current is different for each LED group. Thus, the corresponding timing of starting to supply the current is set as a current supply start light control level for each LED group in accordance with the light control level, and the LED group to be lighted on is selected on the basis of the relationship between the instruction signal (signal representing the light control level) supplied from the instruction section 14 and the corresponding current supply start light control level.
Further, when the first light emitting unit U1″ reaches the full lighting state by starting to light the first LED group D1″, lighting of the second LED group D2″ is started. Then, while the total luminous flux of the first-order light emitted from the second light emitting unit U2″ increases, the full lighting state of the first light emitting unit U1″ is maintained. Hence, after the start of the lighting of the second LED group D2″, in accordance with the increase in the total luminous flux of the synthetic white light emitted from the light emission apparatus 11″, the color temperature of the synthetic white light also increases. Likewise, while lighting of the third LED group D3″ is started and then the total luminous flux of the first-order light emitted from the third light emitting unit U3″ increases, the full lighting states of the first light emitting unit U1″ and the second light emitting unit U2″ are maintained. In addition, while lighting of the fourth LED group D4′ is started and then the total luminous flux of the first-order light emitted from the fourth light emitting unit U4″ increases, the full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″ are maintained. Hence, after the start of the lighting of the third LED group D3″ and after the start of the lighting of the fourth LED group D4″, in accordance with the increase in the total luminous flux of the synthetic white light emitted from the light emission apparatus 11″, the color temperature of the synthetic white light also increases. Furthermore, while lighting of the fifth LED group D5″ is started and then the total luminous flux of the first-order light emitted from the fifth light emitting unit U5″ increases, the full lighting states of the first light emitting unit U1″, the second light emitting unit U2″, the third light emitting unit U3″, and the fourth light emitting unit U4″ are maintained. That is, as the total amount of currents supplied to the plurality of LED groups increases, the respective LED groups are sequentially lighted on. Hence, after the start of the lighting of the fifth LED group D5″, in accordance with the increase in the total luminous flux of the synthetic white light emitted from the light emission apparatus 11″, the color temperature of the synthetic white light also increases. Generally, when the total luminous flux is low, the white light (that is, the light emitted from the filament electric bulb) with a low color temperature is preferred, and when the total luminous flux is high, the white light (that is, the light emitted from the fluorescent lamp) with a high color temperature is preferred. Accordingly, in the light emission apparatus 11″ and the illumination system 12″ according to the present example, in accordance with the increase in the total luminous flux of the synthetic white light, the color temperature is simultaneously controlled. Thereby, it is possible to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux.
(Modified Examples of Pattern Shapes of LED Groups and Wavelength Conversion Regions)
In the above-mentioned example, the fluorescent member 5″ is configured such that a single wavelength conversion region is provided for each division, but the invention is not limited to this. For example, as shown in
As shown in
Further, although not represented by reference signs and numerals, in a similar manner to the above-mentioned example, each LED group corresponding to each wavelength conversion region is provided to be opposed to each wavelength conversion region. In addition, each first LED group D1″ opposed to each first wavelength conversion region P1″ has one LED chip 3a″, each second LED group D2″ opposed to each second wavelength conversion region P2″ has three LED chips 3b″, each third LED group D3″ opposed to each third wavelength conversion region P3″ has two LED chips 3c″, each fourth LED group D4″ opposed to each fourth wavelength conversion region P4″ has two LED chips 3d″, and each fifth LED group D5″ opposed to each fifth wavelength conversion region P5″ has six LED chips 3e″.
In a similar manner to the above-mentioned example, the LED chips 3 in each LED group may be connected in series, or may be connected in parallel.
Further, Literature Kruithof A A: Tubular Luminescence Lamps for General Illumination, Philips Technical Review, 6, pp. 65-96 (1941) describes the illuminance at which a human feels comfortable when the color temperature of the synthetic white light is changed. On the basis of this Literature (hereinafter referred to as Kruithof Literature), if the color temperature of the synthetic white light is intended to be changed while comfort is maintained, it is preferable to control light emission of the light emitting unit at the time of changing the target luminous flux φ in accordance with the target correlation color temperature T such that such that the constant A0, at which the following inequality expression (1) is established, is present.
−80743−(1000/T)5+164973−(1000/T)4−135260−(1000/T)3+57994−(1000/T)2−13995−(1000/T)+1632.9<φ/A0<exp{−342.11−(1000/T)3+450.43−(1000/T)2−212.19×(1000/T)+39.47} (1)
In the above-mentioned first to third examples, the illuminance of the irradiated surface, which faces the fronts of the light emitting section 1, the light emitting section 1′, and the light emitting section 1″ and is positioned at the distance R, is φ/(π·R2). Here, it is assumed that the light distribution of the light emission apparatus is Lambertian. When N light emission apparatuses are provided, by substituting A0=π·R2/N into the inequality expression (1), it is possible to calculate the target luminous flux appropriate for the target correlation color temperature T. Accordingly, when there is a constant A0 at which the relationship between the color temperature and the total luminous flux of the illumination light emitted by the light emission apparatus satisfies the inequality expression (1) in any case, by appropriately setting R and N, it is possible to realize the color temperature, at which a human feels comfortable, even at any illuminance.
When performing the emission control of the above-mentioned first to third examples, by setting R and N corresponding to A0 at which the relationship between the color temperature and the total luminous flux of the illumination light emitted from the light emission apparatus satisfies the above-mentioned Expression (1), on the basis of the description of Kruithof Literature, it is possible to realize illumination for providing the color temperature, at which a human feels comfortable, in accordance with the illuminance even at any light control level. For example, in the light emission apparatus of the second example, by setting R to 2m and N to 70, it is possible to change the illuminance (total luminous flux) and the color temperature in accordance with the relationship indicated by the solid line in
(Effects of the Present Example)
Compared with the light emission apparatus 11 and the illumination system 12 of the first example, the light emission apparatus 11″ and the illumination system 12″ according to the present example is different in the number of LED groups and the number of wavelength conversion regions, but has the same basic structure. Hence, even in the light emission apparatus 11″, the illumination system 12″, and the illumination method according to the present example, it is possible to obtain the same effect as the first example. Further, compared with the light emission apparatuses and the illumination systems of the first example and the second example, in the light emission apparatus 11″ and the illumination system 12″ according to the present example, the number of LED groups and the number of wavelength conversion regions are large. Hence, it is possible to more accurately control the color temperature relative to the change in the luminance of the synthetic white light.
In the above-mentioned first to third examples, the light emission apparatus is configured by using the light emitting unit groups each including the plurality of LED chips 3 mounted on the wiring board 2 and the fluorescent member 5 provided on the transparent board 4. However, the light emission apparatus according to the present invention is not limited to such a form, and may be modified into or replaced with various forms without departing from the technical scope of the present invention. Accordingly, an example of the light emission apparatus, which is configured by using light emitting unit groups different from the light emitting unit groups of the first to third examples, will be described below as a fourth example of the present invention.
(Configuration of Light Emitting Section)
The inside of the reflector 104 is partitioned by the partition member 105 into a first region 106 and a second region 107. In the first region 106, the LED chips 103, which belong to one of the two arrays of the LED chips 103, are disposed. In the second region 107, the LED chips 103, which belong to the other array, are disposed. In addition, the reflector 104 and the partition member 105 can be formed of resin, metal, ceramic, or the like, and is fixed onto the wiring board 102 through an adhesive or the like. Further, when a conductive material is used in the reflector 104 and the partition member 105, a process for providing electrical insulation to a wiring pattern to be described later is necessary.
Note that, in the present example, the number of LED chips 103 is just an example, may be increased or decreased as necessary, may be one for each of the first region 106 and the second region 107, and may be different for each region. Further, the material of the wiring board 102 is not limited to the alumina ceramic, and may use various kinds of materials. For example, it may be possible to use a material selected from ceramic, resin, glass epoxy, and composite resin containing a filler as materials with excellent electrical insulation. Furthermore, in order to improve a light emitting efficiency of the light emitting section 101 by enhancing reflectivity of light on the chip mounting surface 102a of the wiring board 102, it is preferable to use silicon resin including a white pigment such as alumina powder, silica powder, magnesium oxide, or titanium oxide. On the other hand, by using a substrate made of metal such as copper or aluminum, it is possible to improve a heat dissipation ability. However, in this case, it is necessary to form the wiring patterns on the wiring board with electrical insulation performed thereon.
Further, the shapes of the above-mentioned reflector 104 and partition member 105 are also just exemplary shapes, may be modified into various shapes as necessary. For example, instead of the reflector 104 and the partition member 105 formed in advance, an annular wall portion (wall member) corresponding to the reflector 104 may be formed on the chip mounting surface 102a of the wiring board 102 by using a dispenser or the like, and thereafter a partition wall (partition member) corresponding to the partition member 105 may be formed. In this case, the material used in the annular wall portion and the partition wall portion is, for example, a UV curable resin material or a thermosetting resin material having a paste form, and thus silicon resin containing an inorganic filter is appropriate therefor.
As shown in
The wiring patterns 108, 109, 110, and 111 for respectively supplying driving currents to the LED chips 103 are formed on the chip mounting surface 102a of the wiring board 102, as shown in
The four LED chips 103 inside the first region 106 are connected in parallel between the wiring pattern 108 and the wiring pattern 109, which are formed as described above, such that the directions of polarities thereof are the same. More specifically, the LED chip 103 has two electrodes (not shown in the drawing) for supplying driving currents on the surface of the wiring board 102 side. In addition, one electrode (p electrode) of the LED chip 103 is connected to the wiring pattern 108, and the other electrode (n electrode) thereof is connected to the wiring pattern 109. Note that, the LED chips 103 are not limited to be connected in parallel, and may be connected to each other in series.
On the other hand, a connection terminal 110a for external connection is formed at one end of the wiring pattern 110 outside the reflector 104, and the other end side of the pattern inside the second region 107 is provided to extend in parallel with the partition member 105 as shown in
The four LED chips 103 inside the second region 107 are connected in parallel between the wiring pattern 110 and the wiring pattern 111, which are formed as described above, such that the directions of polarities thereof are the same. More specifically, one electrode (p electrode) of the LED chip 103 is connected to the wiring pattern 110, and the other electrode (n electrode) thereof is connected to the wiring pattern 111.
By using flip chip mounting, the LED chips 103 are mounted and both electrodes are connected to the respective wiring patterns with an unillustrated metal bump interposed therebetween through the eutectic solder. Note that, the method of mounting the LED chips 103 on the wiring board 102 is not limited to this, and it may be possible to select a method appropriate for the type, the structure, or the like of the LED chips 103. For example, it may be possible to employ double wire bonding which connects the electrodes of the LED chips 103 to the corresponding wiring patterns through wire bonding after the LED chips 103 are fixedly attached to predetermined positions of the wiring board 102 mentioned above. In addition, it may be possible to employ single wire bonding which bonds one electrode to the wiring pattern as described above and connects the other electrode to the wiring pattern through the wire bonding.
The first region 106 and the second region 107 inside the reflector 104 house fluorescent members (wavelength conversion members) respectively having different wavelength conversion characteristics such that the fluorescent members cover the LED chips 103. In the present example, two types of the fluorescent members are employed. Further, the two types of the fluorescent members are formed of three types of phosphors, and the two types of the fluorescent members are different in the mixture ratio of the phosphors. Accordingly, in the description below, the light emitting section in the first region 106 is referred to as a first light emitting section 101A, and the light emitting section in the second region 107 is referred to as a second light emitting section 101B.
The first light emitting section 101A and the second light emitting section 101B have the same structure mentioned above except the fluorescent members, and all the LED chips 103 also have the same type. Here, for convenience of description, the reference sign 103a is assigned to each LED chip positioned in the first region 106, and the reference sign 103b is assigned to each LED chip positioned in the second region 107. The respective members other than the fluorescent members and the LED chips are represented by common reference signs and numerals in the first light emitting section 101A and the second light emitting section 101B.
The first fluorescent member 112a is excited by the light emitted by the LED chips 103a, and is formed of a plurality of phosphors, which emits light with wavelengths different from that of the light emitted by the LED chips 103a, and a filler for holding the plurality of phosphors in a distributed manner. Further, the second fluorescent member 112b is excited by the light emitted by the LED chips 103b, and is formed of a plurality of phosphors, which emits light with wavelengths different from that of the light emitted by the LED chips 103b, and a filler for holding the plurality of phosphors in a distributed manner. In addition, as the filler, it may be possible to use thermoplastic resin, thermosetting resin, photo curable resin, glass, or the like.
Accordingly, in the present example, the respective combinations of the first and second fluorescent member 112a and 112b and the LED chips 103a and 103b, which are used to correspond thereto, correspond to the respective light emitting units of the present invention. Here, the term “used to correspond” means a situation in which the first fluorescent member 112a is provided to cover the LED chips 103a, the second fluorescent member 112b is provided to cover the LED chips 103b, the wavelength of the light emitted from the LED chips 103a is converted by the first fluorescent member 112a, and the wavelength of the light emitted from the LED chips 103b is converted by the second fluorescent member 112b. Therefore, the LED chips 103a and the first fluorescent member 112a constitute a first light emitting unit U101, and the LED chips 103b and the second fluorescent member 112b constitute a second light emitting unit U102. Further, integrated one of the two types of the light emitting units corresponds to the light emitting unit group of the present invention. Note that, in the description below, light, which is emitted by each of the first light emitting unit U101 and the second light emitting unit U102, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first light emitting unit U101 and the second light emitting unit U102 and is emitted from the light emitting section 101, is referred to as synthetic white light.
(LED Chip)
As the LED chips 103a and 103b, in the present example, the LED chips emitting the blue light with a peak wavelength of 460 nm are used. Specifically, as such an LED chip, there is a GaN LED chip in which for example an InGaN semiconductor is used in a light emitting layer. Note that, the emission wavelength characteristic and the type of the LED chip 103 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. In the present example, it is preferable that the peak wavelengths of the light emitted by the LED chips 103a and 103b be in the wavelength range of 420 nm to 500 nm.
(Fluorescent Member)
In a similar manner to the first wavelength conversion region P1 of the fluorescent member 5 of the first example, the first fluorescent member 112a is configured to emit the first-order light with the chromaticity of the chromaticity point T1 (about 2700 K) in the xy chromaticity diagram of the CIE (1931) XYZ color coordinate system of
By determining the mixture ratio of the phosphors as described above, it is possible to make the color temperature of the first-order light emitted from the second light emitting unit U102 higher than the color temperature of the first-order light emitted from the first light emitting unit U101.
In addition, in a similar manner to the first example, it is not necessary for the first fluorescent member 112a and the second fluorescent member 112b to hold all the above-mentioned red phosphor, green phosphor, and yellow phosphor in a distributed manner, and if the desired first-order light can be emitted from the first fluorescent member 112a and the second fluorescent member 112b, one type or two or more types of phosphors may be selected from the above-mentioned phosphors. For example, the first fluorescent member 112a and the second fluorescent member 112b may hold the red phosphor and the green phosphor in a distributed manner, and may not hold the yellow phosphor in a distributed manner. The other specific composition, structure, and the like of the phosphors are the same as those of the first example.
(Electric Circuit Configuration of Light Emission Apparatus and Control of Light Emitting Section)
As described above, in the light emission apparatus of the present example, the color temperatures of the first-order light, which are respectively emitted from the first light emitting unit U101 and the second light emitting unit U102, are set to be different from each other, and the synthetic white light, which is generated by synthesizing the first-order light emitted from the light emitting units, is emitted from the light emission apparatus. Therefore, in the light emission apparatus of the present example, by changing the total luminous flux (that is, emission intensity or luminance) of the first-order light emitted from each of the first light emitting unit U101 and the second light emitting unit U102, the total luminous flux of the synthetic white light emitted from the light emission apparatus is adjusted, and the color temperature of the synthetic white light is changed in accordance with the corresponding total luminous flux of the synthetic white light so as to emit the synthetic white light with the color temperature appropriate for the desired total luminous flux and the corresponding total luminous flux mentioned above. Accordingly, compared with the light emission apparatus 11 of the first example, the light emission apparatus of the present example has a different exterior configuration, and the first fluorescent member 112a and the second fluorescent member 112b have the same mixture ratios as the first wavelength conversion region P1 and the second wavelength conversion region P2 of the light emitting section 1 of the first example. Hence, the circuit configuration of the inside is the same as the circuit configuration of the light emission apparatus 11. That is, the present example uses a structure in which the first wavelength conversion region P1 and the second wavelength conversion region P2 of the first example are provided to be separated. Therefore, description of the control of the light emitting section and the electric circuit configuration of the light emission apparatus of the present example will be omitted.
(Modified Example of Light Emitting Section)
In the above-mentioned example, by dividing the reflector 104 through the partition member 105, the first region 106 and the second region 107 are formed, the LED chips 103a and the first fluorescent member 112a are provided in the first region 106, and the LED chips 103b and the second fluorescent member 112b are provided in the second region 107, but the invention is not limited to such a structure. However, the invention is not limited to the structure, and the light emitting section 201 or the light emitting section 301 having the structure shown in
In the light emitting section 201 shown in
In the first region 206, the four LED chips 203a and the first fluorescent member 211, which covers the four LED chips 203a, are provided. Accordingly, the four LED chips 203a and the first fluorescent member 211 constitute the first light emitting unit U201. Further, in the second region 207, the four LED chips 203b and the second fluorescent member 212, which covers the four LED chips 203b, are provided. Accordingly, the four LED chips 203b and the second fluorescent member 212 constitute the second light emitting unit U202. Furthermore, in the third region 208, the four LED chips 203c and the third fluorescent member 213, which covers the four LED chips 203c, are provided. Accordingly, the four LED chips 203c and the third fluorescent member 213 constitute the third light emitting unit U203. In addition, in the fourth region 209, the four LED chips 203d and the fourth fluorescent member 214, which covers the four LED chips 203d, are provided. Accordingly, the four LED chips 203d and the fourth fluorescent member 214 constitute the fourth light emitting unit U204. Note that, in
In a similar manner to the first wavelength conversion region P1′ of the fluorescent member 5′ of the second example, the first fluorescent member 211 is configured to emit the first-order light with the chromaticity of the chromaticity point T1 (about 2700 K) in the xy chromaticity diagram of the CIE (1931) XYZ color coordinate system of
Accordingly, in the light emitting section 201 shown in
By determining the mixture ratio of the phosphors as described later, it is possible to set the magnitudes of the color temperatures of the first-order light emitted from the first light emitting unit U201, the second light emitting unit U202, the third light emitting unit U203, and the fourth light emitting unit U204 in order of the first light emitting unit U201, the second light emitting unit U202, the third light emitting unit U203, and the fourth light emitting unit U204.
In addition, in a similar manner to the second example, it is not necessary for the first fluorescent member 211, the second fluorescent member 212, the third fluorescent member 213, and the fourth fluorescent member 214 to hold all the above-mentioned red phosphor, green phosphor, and yellow phosphor in a distributed manner, and if the desired first-order light can be emitted from the first fluorescent member 211, the second fluorescent member 212, the third fluorescent member 213, and the fourth fluorescent member 214, one type or two or more types of phosphors may be selected from the above-mentioned phosphors. For example, the first fluorescent member 211, the second fluorescent member 212, the third fluorescent member 213, and the fourth fluorescent member 214 may hold the red phosphor and the green phosphor in a distributed manner, and may not hold the yellow phosphor in a distributed manner. The other specific composition, structure, and the like of the phosphors are the same as those of the first example.
In addition, compared with the light emitting section 1′ of the second example, the light emission apparatus 201 shown in
In the light emitting section 301 shown in
In the first region 306, the four LED chips 303a and the first fluorescent member 311, which covers the four LED chips 303a, are provided. Accordingly, the four LED chips 303a and the first fluorescent member 311 constitute the first light emitting unit U301. Further, in the second region 307, the four LED chips 303b and the second fluorescent member 312, which covers the four LED chips 303b, are provided. Accordingly, the four LED chips 303b and the second fluorescent member 312 constitute the second light emitting unit U302. Furthermore, in the third region 308, the four LED chips 303c and the third fluorescent member 313, which covers the four LED chips 303c, are provided. Accordingly, the four LED chips 303c and the third fluorescent member 313 constitute the third light emitting unit U303. In addition, in the fourth region 309, the four LED chips 303d and the fourth fluorescent member 314, which covers the four LED chips 303d, are provided. Accordingly, the four LED chips 303d and the fourth fluorescent member 314 constitute the fourth light emitting unit U304. Likewise, in the fifth region 310, the four LED chips 303e and the fifth fluorescent member 315, which covers the four LED chips 303e, are provided. Accordingly, the four LED chips 303e and the fifth fluorescent member 315 constitute the fifth light emitting unit U305. Note that, in
In a similar manner to the first wavelength conversion region P1″ of the fluorescent member 5″ of the third example, the first fluorescent member 311 is configured to emit the first-order light with the chromaticity of the chromaticity point T1 (about 2050 K) in the xy chromaticity diagram of the CIE (1931) XYZ color coordinate system of
Accordingly, in the light emitting section 301 shown in
By determining the mixture ratio of the phosphors as described later, it is possible to set the magnitudes of the color temperatures of the first-order light emitted from the first light emitting unit U301, the second light emitting unit U302, the third light emitting unit U303, the fourth light emitting unit U304, and the fifth light emitting unit U305 in order of the first light emitting unit U301, the second light emitting unit U302, the third light emitting unit U303, the fourth light emitting unit U304, and the fifth light emitting unit U305.
In addition, in a similar manner to the third example, it is not necessary for the first fluorescent member 311, the second fluorescent member 312, the third fluorescent member 313, the fourth fluorescent member 314, and the fifth fluorescent member 315 to hold all the above-mentioned red phosphor, green phosphor, and yellow phosphor in a distributed manner. If the desired first-order light can be emitted from the first fluorescent member 311, the second fluorescent member 312, the third fluorescent member 313, the fourth fluorescent member 314, and the fifth fluorescent member 315, one type or two or more types of phosphors may be selected from the above-mentioned phosphors. For example, the first fluorescent member 311, the second fluorescent member 312, the third fluorescent member 313, the fourth fluorescent member 314, and the fifth fluorescent member 315 may hold the red phosphor and the green phosphor in a distributed manner, and may not hold the yellow phosphor in a distributed manner. The other specific composition, structure, and the like of the phosphors are the same as those of the first example.
In addition, compared with the light emitting section 1″ of the third example, the light emission apparatus 301 shown in
(Effects of the Present Example)
Compared with the light emission apparatus 11 and the illumination system 12 of the first example, the light emission apparatus and the illumination system according to the present example is different in the number of LED groups and the number of wavelength conversion regions, but has the same basic structure. Hence, even in the light emission apparatus, the illumination system, and the illumination method according to the present example, it is possible to obtain the same effect as the first example.
In addition, the material of the wiring board 502 is not limited to the alumina ceramic, and the main body of the wiring board 502 may be formed of a material selected from, for example, resin, glass epoxy, and composite resin containing a filler as materials with excellent electrical insulation. Alternatively, in order to improve a light emitting efficiency of the light emitting section 501 by enhancing reflectivity of light on the chip mounting surface 502a of the wiring board 502, it is preferable to use silicon resin including a white pigment such as alumina powder, silica powder, magnesium oxide, or titanium oxide. On the other hand, in order to obtain a further excellent heat dissipation ability, the main body of the wiring board 502 may be made of metal. In this case, it is necessary to electrically insulate the wiring patterns and the like of the wiring board 502 from the main body made of metal.
As shown in
A fluorescent member (wavelength conversion member) 505 is provided on the second surface 504b of the transparent board 504, which is opposite to the first surface 504a facing the wiring board 502, so as to cover the LED chips 503 mounted on the wiring board 502. Accordingly, the fluorescent member 505 is disposed at a position where it is opposed to the chip mounting surface 502a of the wiring board 502 with the transparent board 504 interposed therebetween. The fluorescent member 505 is divided into a plurality of cell regions 506 corresponding to the respective LED chips 503 which are positioned to be opposed thereto. As shown in
As described later in detail, the fluorescent member 505 has a function of converting the wavelength of the light emitted by the LED chips 503 and emitting light with a peak wavelength different from the light emitted by the LED chips 503. As described above, since the fluorescent member 505 is divided into 160 cell regions 506, each cell region 506 is provided to correspond to each LED chip 503. Therefore, light emitted for the respective cell regions 506 corresponding to the LED chips 503, which are emitting light, are synthesized and emitted from the fluorescent member 505. Then, the light emitted from the fluorescent member 505 becomes illumination light of the illumination apparatus of the present example.
Such cell regions 506 are grouped, as shown in
In accordance with the division of the fluorescent member 505, the LED chips 503 mounted on the wiring board 502 are grouped into respective LED groups corresponding to respective positions of the first wavelength conversion region P51, the second wavelength conversion region P52, the third wavelength conversion region P53, and the fourth wavelength conversion region P54 as shown in
That is, the 40 LED chips 503a positioned to correspond to the first wavelength conversion region P51 constitute a first LED group D51, and the 40 LED chips 503b positioned to correspond to a second wavelength conversion region P52 constitute a second LED group D52. In addition, the 40 LED chips 503c positioned to correspond to the third wavelength conversion region P53 constitute a third LED group D53, and the 40 LED chips 503d positioned to correspond to the fourth wavelength conversion region P54 constitute a fourth LED group D54.
Accordingly, in the present example, respective combinations of the first to fourth wavelength conversion regions P51 to P54 and first to fourth LED groups D51 to D54 corresponding thereto correspond to respective light emitting units of the present invention. That is, the first LED group D51 and the first wavelength conversion region P51 constitute a first light emitting unit U51, and the second LED group D52 and the second wavelength conversion region P52 constitute a second light emitting unit U52. Further, the third LED group D53 and the third wavelength conversion region P53 constitute a third light emitting unit U53, and the fourth LED group D54 and the fourth wavelength conversion region P54 constitute a fourth light emitting unit U54. A light emitting section 501, in which the four light emitting units are integrated, corresponds to a light emitting unit group of the present invention. Note that, in the description below, light, which is emitted by each of the first to fourth light emitting units U51 to U54, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first to fourth light emitting units U51 to U54 and is emitted from the light emitting section 501, is referred to as synthetic light.
The clearance provided herein is formed with a distance L51 calculated in advance such that the light emitted from the LED chip 503 reliably reaches the cell region 506 of the fluorescent member 505 positioned to correspond to the LED chip 503 and an amount of light, which leaks to the different cell regions 506 adjacent to the corresponding cell region 506 is reduced. That is, for example, as shown in
In order to achieve this, in the present example, the space between the LED chip 503 and the fluorescent member 505 should be less than or equal to 5 mm, and thus the clearance distance L51 is determined such that a total thickness of the clearance and the transparent board 504 is less than or equal to 5 mm. It is the same for all the LED chips 503 in the present example. By providing the clearance with the distance L51, it is possible to reliably prevent light from leaking to other adjacent cell regions. As a result, by adopting the configuration in which the fluorescent member 505 is positioned to be opposed to the LED chip 503 together with the above configuration, it is possible to accurately perform the wavelength conversion in the fluorescent member 505, and it is possible to ensure high light emitting efficiency.
In addition, when the LED chips 503 are made to be as close to the corresponding cell regions 506 as possible, the light emitted by the LED chips 503 reliably reach the cell regions 506. However, when the LED chips 503 are excessively close to the cell regions 506, the cell regions 506 are heated by heat emitted by the LED chips 503, and thus there is a concern that this causes deterioration in the wavelength conversion function and the light emitting efficiency. For this reason, in order to prevent the temperature thereof from being excessively increased, it is preferable that the distance between the LED chips 503 and the fluorescent member 505 be greater than and equal to 0.01 mm. Accordingly, considering the thickness of the transparent board 504, the clearance distance L51 is determined such that the distance between the LED chips 503 and the fluorescent member 505 be in the range of 0.01 mm to 5 mm.
In the present example, the clearance distance L51 is set to 0.1 mm, and on the basis of L53 which is obtained by adding the height L52 of each LED chip 503 to the clearance distance, the distance between the first surface 504a of the transparent board 504 and the chip mounting surface 502a of the wiring board 502 is defined. In addition, when the light emitting section 501 has thermal room, the thickness of the transparent board 504 is determined such that the distance between the LED chips 503 and cell regions 506 is set to an appropriate distance as described above in the state where the first surface 504a of the transparent board 504 may be in close contact with the LED chips 503 without providing such a clearance. Furthermore, even when the LED chips 503 and the transparent board 504 are separated, the clearance may be sealed by silicon resin, epoxy resin, glass, or the like which is transparent. In such a manner, it is possible to efficiently guide the light emitted from the LED chips 503 to the fluorescent member 505.
In addition, in the present example, the fluorescent member 505 is provided on the second surface 504b of the transparent board 504, but the fluorescent member 505 may be provided on the first surface 504a of the transparent board 504, that is, a surface thereof close to the wiring board 502. Even in this case, in a similar manner to the present example, it is possible to provide an appropriate clearance between the fluorescent member 505 and the LED chips 503. However, when there is thermal room, it is possible to cause the fluorescent member 505 to be in close contact with the LED chips 503 or to be close thereto just before the contact.
(LED Chip)
As the LED chip 503, in the present example, an LED chip emitting blue light with a peak wavelength of 460 nm is used. Specifically, as such an LED chip, there is a GaN LED chip in which for example an InGaN semiconductor is used in a light emitting layer. Note that, the emission wavelength characteristic and the type of the LED chip 503 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. In the present example, it is preferable that the peak wavelength of the light emitted by the LED chips 503 be in the wavelength range of 420 nm to 500 nm.
A p electrode 508 and an n electrode 509 are formed on a surface of each LED chip 503 facing the wiring board 502. In a case of the LED chip 503 shown in
Note that, a method of mounting the LED chips 503 on the wiring board 502 is not limited to this, and it may be possible to select a method appropriate for the type, the structure, and the like of the LED chip 503. For example, after the LED chips 503 are fixedly attached to predetermined positions on the wiring board 502, the two electrodes of each LED chip 503 may be connected to the corresponding wiring patterns through wire bonding. In addition, one electrode may be bonded to the corresponding wiring pattern as described above, and the other electrode may be connected to the corresponding wiring pattern through wire bonding.
(Fluorescent Member)
As described above, the fluorescent member 505 is divided into 160 cell regions 506 corresponding to positions of the respective LED chips 503 mounted on the wiring board 502. The cell regions 506 are divided into four types of red cells (first cell regions) 506r, green cells (second cell regions) 506g, yellow cells (third cell regions) 506y, and blue cells (fourth cell regions) 506b. In the red cells 506r, red phosphors (first phosphors), which are for emitting red light by converting the wavelength of the blue light emitted by the LED chips 503, are held in a distributed manner. Accordingly, the red cells 506r emit red light, which is subjected to the wavelength conversion and is emitted from the red phosphors, and blue light of the LED chips 503 which is transmitted through the red cells 506r without the wavelength conversion performed through the red phosphors.
Further, in the green cells 506g, green phosphors (second phosphors), which are for emitting green light by converting the wavelength of the blue light emitted by the LED chips 503, are held in a distributed manner. Accordingly, the green cells 506g emit green light, which is subjected to the wavelength conversion and is emitted from the green phosphors, and blue light of the LED chips 503 which is transmitted through the green cells 506g without the wavelength conversion performed through the green phosphors.
In addition, in the yellow cells 506y, yellow phosphors (third phosphors), which are for emitting yellow light by converting the wavelength of the blue light emitted by the LED chips 503, are held in a distributed manner. Accordingly, the yellow cells 506y emit yellow light, which is subjected to the wavelength conversion and is emitted from the yellow phosphors, and blue light of the LED chips 503 which is transmitted through the yellow cells 506y without the wavelength conversion performed through the yellow phosphors.
On the other hand, in each blue cell 506b, diffusing particles for satisfactorily diffusing and emitting blue light are held in a distributed manner in the cell region which transmits the blue light emitted by the LED chip 503 without wavelength conversion. As the diffusing particles, specifically, it is preferable to use alumina, titania, zirconia, silica, or the like. Accordingly, the blue cells 506b emit blue light of the LED chips 503 which is transmitted through the blue cells 506b without the wavelength conversion.
A fluorescent member 505 is divided into four wavelength conversion regions of the first wavelength conversion region P51, the second wavelength conversion region P52, the third wavelength conversion region P53, and the fourth wavelength conversion region P54. However, there are differences in the numbers of cell regions of four types of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b included in each of the four wavelength conversion regions.
In each wavelength conversion region of the first wavelength conversion region P51, the second wavelength conversion region P52, the third wavelength conversion region P53, and the fourth wavelength conversion region P54, when the LED chips 503 emit light, in order to satisfactorily synthesize light emitted from the cell regions, the cell regions are distributed such that the cell regions having the same type are prevented from being adjacent to one another as far as possible.
By arranging the cell regions 506 having the plurality of types in each wavelength conversion region in a distributed manner as shown in
In the second wavelength conversion region P52, as shown in
Further, in the third wavelength conversion region P53, as shown in
In addition, when each LED chip 503d of the fourth LED group D54 corresponding to the fourth wavelength conversion region P54 emits light, the fourth wavelength conversion region P54, that is, the fourth light emitting unit U54 emits the first-order light in which the red light, the green light, the yellow light, and the blue light emitted from the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b are synthesized. In the present example, as described above, the number of red cells 506r, the number of green cells 506g, the number of yellow cells 506y, and the number of blue cells 506b in the fourth wavelength conversion region P54 are determined such that the first-order light, which is emitted from the fourth light emitting unit U54, has the chromaticity of the chromaticity point WP4 of
As shown in
Note that, the chromaticity points of the first-order light respectively emitted by the first to fourth light emitting units U51 to U54 are not limited to the chromaticity points WP1 to WP4 shown in
Further, in a similar manner to the present example, in the case of using the four light emitting units, in a similar manner to the chromaticity points WP1 to WP4 shown in
Here, specific examples of various phosphors respectively applicable to the red cell 506r, the green cell 506g, and the yellow cell 506y will be described below. Note that, the phosphors exemplify phosphors quite appropriate for the present example. However, available phosphors are not limited thereto, and it may be possible to apply various types of phosphors insofar as they are within the technical scope of the present invention.
(Red Phosphor)
An appropriate wavelength range of the emission peak wavelength of the red phosphor is normally 570 nm or more and 780 nm or less, preferably 580 nm or more and 700 nm or less, or more preferably 585 nm or more and 680 nm or less. From this point of view, as the red phosphor, for example, the following are preferable: (Ca, Sr, Ba)2Si5(N, O)8Eu; (Ca, Sr, Ba)Si(N, O)2:Eu; (Ca, Sr, Ba)AlSi(N, O)3:Eu; (Sr, Ba)3SiO5:Eu; (Ca, Sr)S:Eu; SrAlSi4N7:Eu; (La, Y)2O2S:Eu; Eu(dibenzoylmethane)3-1; β-diketone Eu complexes such as 10-phenanthroline complex; carboxylic acid Eu complex; and K2SiF6:Mn. In addition, the following are more preferable: (Ca, Sr, Ba)2Si5(N, O)8:Eu; (Sr, Ca)AlSi(N, O)3:Eu; SrAlSi4N7:Eu; (La, Y)2O2S:Eu; and K2SiF6:Mn.
(Orange Phosphor)
The orange phosphor, of which the emission peak wavelength is in the range of 580 nm or more and 620 nm or less or preferably in the range of 590 nm or more and 610 nm or less, can be appropriately used instead of the red phosphor. Examples of such an orange phosphor include: (Sr, Ba)3SiO5:Eu; (Sr, Ba)2SiO4:Eu; (Ca, Sr, Ba)2Si5(N, O)8:Eu; (Ca, Sr, Ba)AlSi(N, O)3:Ce; and the like.
(Green Phosphor)
An appropriate wavelength range of the emission peak wavelength of the green phosphor is normally 500 nm or more and 550 nm or less, preferably 510 nm or more and 542 nm or less, or more preferably 515 nm or more and 535 nm or less. From this point of view, as the green phosphor, for example, the following are preferable: Y3(Al, Ga)5O12:Ce; CaSc2O4:Ce; Ca3(Sc, Mg)2Si3O12:Ce; (Sr, Ba)2SiO4:Eu; (Si, Al)6(O, N)8:Eu(β-sialon); (Ba, Sr)3Si6O12:N2:Eu; SrGa2S4:Eu; BaMgAl10O17:Eu; and Mn.
(Yellow Phosphor)
An appropriate wavelength range of the emission peak wavelength of the yellow phosphor is normally 530 nm or more and 620 nm or less, preferably 540 nm or more and 600 nm or less, or more preferably 550 nm or more and 580 nm or less. From this point of view, as the yellow phosphor, for example, the following are preferable: Y3Al5O12:Ce; (Y, Gd)3Al5O12:Ce; (Sr, Ca, Ba, Mg)2SiO4:Eu; (Ca, Sr)Si2N2O2:Eu; α-sialon; and La3Si6N11:Ce (here, a part thereof may be replaced with Ca or O).
(Electric Circuit Configuration of Illumination Apparatus)
As described above, in the illumination apparatus of the present example, the color temperatures of the first-order light, which are respectively emitted from the first to fourth light emitting units U51 to U54, are set to be different from each other, and the synthetic light, which is generated by synthesizing the first-order light emitted from the light emitting units, is emitted as illumination light of the illumination apparatus. Therefore, the illumination apparatus of the present example emits white light with various color temperatures as illumination light by adjusting the intensity of the first-order light which is emitted from each of the first to fourth light emitting units U51 to U54. Here, an electric circuit configuration of the illumination apparatus configured to change the intensity of the first-order light emitted from each light emitting unit will be described with reference to
Specifically, the LED chips 503a of the first LED group D51 are connected to one another in parallel such that the polarities thereof are the same, and the anode of each LED chip 503a is connected to the positive terminal of the power supply 512 through the resistor R1. Further, the cathode of each LED chip 503a is connected to the collector of the transistor Q51, and the emitter of the transistor Q51 is connected to the negative terminal of the power supply 512. In a similar manner to the LED chips 503a, the LED chips 503b of the second LED group D52 are connected to one another in parallel such that the polarities thereof are the same, and each anode is connected to the positive terminal of the power supply 512 through the resistor R2, and each cathode is connected to the negative terminal of the power supply 512 through the transistor Q52. Further, in a similar manner to the LED chips 503a, the LED chips 503c of the third LED group D53 are connected to one another in parallel such that the polarities thereof are the same, and each anode is connected to the positive terminal of the power supply 512 through the resistor R3, and each cathode is connected to the negative terminal of the power supply 512 through the transistor Q53. Furthermore, in a similar manner to the LED chips 503a, the LED chips 503d of the fourth LED group D54 are connected to one another in parallel such that the polarities thereof are the same, and each anode is connected to the positive terminal of the power supply 512 through the resistor R4, and each cathode is connected to the negative terminal of the power supply 512 through the transistor Q54.
In such an electric circuit configuration, by turning on the transistor Q51, forward currents supplied from the power supply 512 flow in the respective LED chips 503a of the first LED group D51, and thereby the LED chips 503a respectively emit light. Accordingly, by turning on the transistor Q51, the first light emitting unit U51, which is formed of the first LED group D51 and the first wavelength conversion region P51 corresponding thereto, emits the first-order light with the chromaticity of the chromaticity point WP1 in
Likewise, by turning on the transistor Q52, forward currents supplied from the power supply 512 flow in the respective LED chips 503b of the second LED group D52, and thereby the LED chips 503b respectively emit light. Accordingly, by turning on the transistor Q52, the second light emitting unit U52, which is formed of the second LED group D52 and the second wavelength conversion region P52 corresponding thereto, emits the first-order light with the chromaticity of the chromaticity point WP2 in
Further, by turning on the transistor Q53, forward currents supplied from the power supply 512 flow in the respective LED chips 503c of the third LED group D53, and thereby the LED chips 503c respectively emit light. Accordingly, by turning on the transistor Q53, the third light emitting unit U53, which is formed of the third LED group D53 and the third wavelength conversion region P53 corresponding thereto, emits the first-order light with the chromaticity of the chromaticity point WP3 in
Furthermore, by turning on the transistor Q54, forward currents supplied from the power supply 512 flow in the respective LED chips 503d of the fourth LED group D54, and thereby the LED chips 503d respectively emit light. Accordingly, by turning on the transistor Q54, the fourth light emitting unit U54, which is formed of the fourth LED group D54 and the fourth wavelength conversion region P54 corresponding thereto, emits the first-order light with the chromaticity of the chromaticity point WP4 in
In order to control on/off states of the transistors Q51 to Q54, the illumination apparatus of the present example is provided with an emission control section 513. All the transistors Q51 to Q54 are able to switch the on/off states in response to the respective base signals, and the emission control section 513 is configured to individually transmit the base signals to the respective bases.
The intensities of the first-order light which is respectively emitted from the first to fourth light emitting units U51 to U54 are maximized in a state where the corresponding transistors Q51 to Q54 are consecutively turned on. Accordingly, in the present example, the emission control section 513 consecutively turns on any of the transistors Q51 to Q54 in such a manner, whereby it is possible to maximize the intensity of the first-order light which is emitted from the light emitting unit corresponding to the transistor. Meanwhile, when the intensity of the first-order light emitted from any of the first to fourth light emitting units U51 to U54 is lowered from the maximum thereof, the transistor corresponding to the light emitting unit is intermittently turned on and off with a predetermined cycle, and the duty ratio of the current supply pulses at this time is adjusted, thereby adjusting the electric power supplied to the LED group of the light emitting unit. Furthermore, by reducing the duty ratio of the current supply pulses at this time, the electric power for causing the LED chips 503 to emit light is not supplied, and then the light emitting unit having the LED chips 503 does not emit the first-order light.
As shown in
In the illumination apparatus of the present example, the synthetic light, which is generated by synthesizing the first-order light emitted by the first to fourth light emitting units U51 to U54, is the illumination light of the illumination apparatus. Therefore, in such a manner, by adjusting the intensity of the first-order light with a different chromaticity emitted from each of the first to fourth light emitting units U51 to U54, it is possible to adjust the chromaticity of the illumination light of the illumination apparatus to various values. Accordingly, in order to generate the desired illumination light, the illumination apparatus of the present example is provided with an operation unit (operation member) 514 by which a user performs operation, and a target value setting section 515 that sets a target value for appropriately adjusting the chromaticity of the illumination light in accordance with the operation performed on the operation unit 514. In the present example, the emission control section 513, the operation unit 514, and the target value setting section 515 constitute the control means of the present invention.
This indications correspond to the color temperatures of the white light emitted as the illumination light by the illumination apparatus, and thus assist a user to grasp the level of the color temperature more intuitively than a case where the own numerical values of the color temperatures are inscribed on the main body 514b. Specifically, for example, the “electric bulb color” indicates about 2550° K, the “warm white” indicates about 3500° K, the “white” indicates about 4200° K, the “day white” indicates about 5000° K, and the “daylight color” indicates about 6400° K. The operation dial 514a may be formed to be rotated stepwise in accordance with the indications, and may be formed to be continuously rotated.
(Control of Light Emitting Section)
The main body 514b of the operation unit 514 detects the position of the operation dial 514a, and notifies the detected position of the operation dial 514a to the target value setting section 515. The target value setting section 515 determines the target correlation color temperature corresponding to the detected position of the operation dial 514a, on the basis of the relationship between the target correlation color temperature and the position of the operation dial 514a which is set in advance to match with the indication on the main body 514b of the operation unit 514. The target correlation color temperature determined in such a manner is sent from the target value setting section 515 to the emission control section 513. Then, the emission control section 513 performs emission control for controlling light emission of the light emitting section 501 in response to the target correlation color temperature sent from the target value setting section 515.
At this time, the emission control, which is performed by the emission control section 513, is to control the intensity of the first-order light, which is emitted from each of the first to fourth light emitting units U51 to U54, such that the illumination light emitted from the illumination apparatus is made to be the white light with the target correlation color temperature which is set through the operation unit 514. Specifically, the emission control is performed such that the chromaticity of the illumination light is positioned on the control curve CL in the XY chromaticity diagram of
Further, as shown in
In addition, in the present example, the lower limit color temperature T1 is set to 2550 K, and the upper limit color temperature T2 is set to 6400 K such that they match with the range of color temperature which is set by the above-mentioned operation unit 514. By setting the lower limit color temperature T1 and the upper limit color temperature T2 as described above, it is possible to emit the illumination light in the color temperature range of the illumination light, which is obtained in a general illumination apparatus, from the illumination apparatus. The lower limit color temperature T1 and the upper limit color temperature T2 are not limited to the above-mentioned values, and may be increased or decreased as necessary. However, when the illumination light in the color temperature range of the illumination light obtained in the general illumination apparatus is intended to be emitted from the illumination apparatus, the lower limit color temperature T1 is preferably less than and equal to 2800 K, and the upper limit color temperature T2 is preferably greater than or equal to 6000 K.
The illumination light, which is emitted from the illumination apparatus, is generated by synthesizing the first-order light which is respectively emitted from the first to fourth light emitting units U51 to U54. Therefore, it is necessary for at least one of the four chromaticity points WP1 to WP4 to be on the low color temperature side of the lower limit color temperature T1 of the control curve CL, and to be on the high color temperature side of the upper limit color temperature T2 of the control curve CL. Accordingly, in the case of the present example, the chromaticity point WP3, which is the minimum color temperature of the four chromaticity points WP1 to WP4, is set on the low color temperature side of the lower limit color temperature T1 of the control curve CL. In addition, the chromaticity point WP2, which is the maximum color temperature, and the chromaticity point WP4, which is the second-highest color temperature, are set on the high color temperature side of the upper limit color temperature T2 of the control curve CL.
Further, as described above, the control curve CL is set to be included in the rectangle which is formed such that the vertexes thereof are the chromaticity points WP1 to WP4, and each of the chromaticity points WP1 to WP4 is positioned outside the triangle which is formed such that the vertexes thereof are the other three chromaticity points. If the chromaticity point of the first-order light emitted by any one light emitting unit of the first to fourth light emitting units U51 to U54 is inside the triangle which is formed such that the vertexes thereof are the other three chromaticity points, at a certain color temperature of the adjusted illumination light, instead of the two light emitting units corresponding to both chromaticity points adjacent to the chromaticity point inside the triangle, it may suffice to use the light emitting unit corresponding to the chromaticity point inside the triangle. In this case, the total luminous flux of the illumination light is lowered, and thus there is a concern that it is difficult to obtain the necessary total luminous flux. Accordingly, in the present example, when each of the chromaticity points WP1 to WP4 is positioned outside the triangle which is formed such that the vertexes thereof are the other three chromaticity points, it is possible to cause each of the first to fourth light emitting units U51 to U54 to emit light as uniformly as possible. As a result, it is possible to ensure the total luminous flux necessary for the illumination light.
As described above, the sum of the upper limits of the electric powers, which can be supplied to the light emitting units, is set to be greater than the upper limit of the sum power which can be supplied to the light emitting section 501. Therefore, it is possible to set the sum of the electric powers, which are respectively supplied to the first to fourth light emitting units U51 to U54, to not more than 8 W as the upper limit of the sum power which can be supplied to the light emitting section 501 while setting the electric power, which is supplied to any light emitting unit of the first to fourth light emitting units U51 to U54, to 4 W as the upper limit. As a result, compared with the case where the sum of the upper limits of the electric powers which can be supplied to the light emitting units is limited to be less than or equal to the upper limit of the sum power which can be supplied to the light emitting section 501, it is possible to increase the total luminous flux of the illumination light emitted from the illumination apparatus.
Note that, the upper limit of the electric power, which can be supplied to the light emitting section 501, indicated herein and the upper limits of the electric powers, which can be supplied to the light emitting units, are just examples, and the invention is not limited to them, and may be appropriately changed in accordance with specification of each light emitting unit or the illumination apparatus. In any case, in view of the advantage that it is possible to increase the total luminous flux of the illumination light emitted from the illumination apparatus, it is preferable that the sum of the upper limits of the electric powers, which can be supplied to the light emitting units, be set to be greater than the upper limit of the sum power which can be supplied to the light emitting section 501.
In such a manner, the control curve CL is determined, and the upper limit of the electric powers, which can be respectively supplied to the first to fourth light emitting units U51 to U54, is determined. Thereby, as shown in
In addition, in the region in which the color temperature is less than or equal to 4000 K, in order to eliminate sense of discomfort caused by change in the color temperature and the total luminous flux of a general incandescent bulb, the total luminous flux is decreased in accordance with the decrease in the color temperature of the illumination light of the illumination apparatus. However, in the present example, even in such a case, until the color temperature is decreased up to the lower limit color temperature T1, the total luminous flux, which is greater than and equal to ⅓ of the maximum luminous flux, is ensured. In such a manner, by suppressing the decrease in the total luminous flux of the illumination light in the case of decreasing the color temperature, it is possible to generate bright illumination light even at the low color temperature.
The relationships between the supply power and the color temperature of the illumination light mentioned above are figured out in advance by performing simulations, experiments, or the like. Thus, on the basis of the relationships obtained from the results thereof as shown in
Accordingly, in the present example, on the basis of the relationship between the color temperature and the supply power supplied to each light emitting unit in
When receiving the target correlation color temperature corresponding to the operation position of the operation dial 514a of the operation unit 514 from the target value setting section 515, the emission control section 513 acquires the amount of on/off control of each of the transistors Q51 to Q54 corresponding to the target correlation color temperature from the control map stored in the memory 513a, and controls on and off states of the transistors Q51 to Q54 of the light emitting section 501 on the basis of the acquired amount of control. As a result, the illumination light with the color temperature, of which the chromaticity is in the control curve CL in the XY chromaticity diagram of
As described above, in the control curve CL in the XY chromaticity diagram of
As described above, in the illumination apparatus of the present example, it is possible to change the color temperature of the illumination light emitted from the illumination apparatus in the range from the lower limit color temperature T1 to the upper limit color temperature T2 in accordance with the operation amount of the operation dial 514a of the operation unit 514. At this time, the chromaticity of the illumination light is approximate to the black-body radiation locus BL, and the deviation Δuv is within +0.005, and thus it is possible to make the illumination light be white light which is natural without sense of discomfort. In addition, both the color temperature of the illumination light and the total luminous flux are appropriately adjusted by the operation performed on the operation dial 514a.
Further, in the XY chromaticity diagram of
Furthermore, in the present example, the LED chips 503 and the cell regions 506 containing the phosphors are used in combination. Therefore, by using the emission spectrum characteristics of the phosphors, it is possible to generate illumination light excellent in the color rendering property without the missing parts which occur in the emission spectrum of each light emitting unit when the light emitted by the LED chips is used as it is.
Moreover, in each cell region 506, the plurality kinds of phosphors with different wavelength conversion characteristics are not used in a mixed manner. Hence, it is possible to suppress occurrence of cascade excitation that the light of which the wavelength is converted by one phosphor is subjected to the wavelength conversion again by the other phosphor. Thus, it is possible to prevent the light emitting efficiency from being decreased in each wavelength conversion region by such cascade excitation.
In addition, in the present example, the transparent board 504, on which the fluorescent member 505 is provided, is provided to be opposed to the wiring board 502 on which the LED chips 503 are mounted, thereby forming the light emitting section 501 having the light emitting unit group. Therefore, since the first to fourth light emitting units U51 to U54 are integrally formed, it becomes easy to treat the light emitting section 501, and it is possible to reduce the manufacturing costs and the number of manufacturing processes of the illumination apparatus.
(Modified Example of Electric Circuit Configuration of Illumination Apparatus)
The above-mentioned configuration shown in
In the present modified example, in a similar manner to the fifth example, the 40 LED chips 503a constitute the first LED group D51, and the 40 LED chips 503b constitute the second LED group D52. Likewise, the 40 LED chips 503c constitute the third LED group D53, and the 40 LED chips 503d constitute the fourth LED group D54. Here, as shown in
As shown in
The bases of the bases of the transistors Q61 to Q64 are connected to the output of operational amplifiers OP1 to OP4. In addition, the inverting inputs of the respective operational amplifiers OP1 to OP4 are connected, as shown in
Likewise, the operational amplifier OP2, the resistor R22, and the transistor Q62 constitute a constant current circuit for the driving current supplied to the LED chips 503b. The operational amplifier OP3, the resistor R23, and the transistor Q63 constitute a constant current circuit for the driving current supplied to the LED chips 503c. The operational amplifier OP4, the resistor R24, and the transistor Q64 constitute a constant current circuit for the driving current supplied to the LED chips 503d. In addition, the magnitudes of the driving currents of the LED chips 503b to 503d are determined depending on the electric potentials of the non-inverting inputs of the operational amplifiers respectively corresponding thereto like the case of the LED chips 503a.
In the present modified example, when the driving current is supplied to only any one of the first to fourth LED groups D51 to D54, the first-order light, which is emitted from the light emitting unit corresponding to the LED group of the first to fourth light emitting units U51 to U54, is also the same as that of the above-mentioned fifth example. That is, when each LED chip 503a of the first LED group D51 emits light, the first-order light with the chromaticity of the chromaticity point WP1 of
By controlling light emission of the first to fourth light emitting units U51 to U54, in a similar manner to the illumination apparatus of the fifth example, the chromaticity of the illumination light, which is emitted from the illumination apparatus by synthesizing the first-order light which is emitted from each of the first to fourth light emitting units U51 to U54, is changed in the control curve CL shown in
The micro computer CPU1 includes two analog input ports IP1 and IP2, and includes four digital output ports #1, #2, #3, and #4 that output 8-bit digital signals. Further, the memory M1 is connected to the micro computer CPU1 through a signal line so as to interchange data with the micro computer CPU 1. In addition, the D/A converter DAC 1 includes four digital input ports DP1, DP2, DP3, and DP4, and includes analog output ports AP1, AP2, AP3, and AP4 that convert the digital signals, which are input to the digital input ports DP1, DP2, DP3, and DP4, into analog signals and output them. In addition, the digital input ports DP1, DP2, DP3, and DP4 correspond one-to-one with the analog output ports AP1, AP2, AP3, and AP4 in this order.
The variable resistor VR1 is provided, in the same form as the operation unit 514 of the fifth example, in the illumination apparatus so as to be operated by the color temperature adjustment dial (not shown in the drawing) which assists a user to perform an operation to adjust the color temperature of the illumination light. One of two fixed terminals of the variable resistor VR1 are connected to the positive terminal of the power supply 522, and the other is connected to the negative terminal of the power supply 522. On the other hand, the variable terminal is connected to the analog input port IP1 of the micro computer CPU1, and the electric potential, which is applied to the analog input port IP1, is changed by the operation of a user performed on the color temperature adjustment dial.
In the present modified example, the emission control is performed such that, when the electric potential of the variable terminal of the variable resistor VR1 is minimized, the color temperature of the illumination light reaches the lower limit color temperature (first color temperature) T1 in the control curve CL of
As described above, the electric potential of the variable terminal of the variable resistor VR1 corresponds one-to-one with the color temperature of the illumination light designated by the operation of the color temperature adjustment dial, and the target correlation color temperature of the illumination light is determined on the basis of the electric potential of the variable terminal of the variable resistor VR1. On the other hand, the distribution of the electric powers, which are supplied to the first to fourth light emitting units U51 to U54, for achieving the set target correlation color temperature in the control curve CL is the same as that of the above-mentioned fifth example, and in the same method, the amount of the electric power supplied to each light emitting unit is calculated in advance on the basis of the target correlation color temperature which can be set. Further, when the electric powers supplied to the first to fourth light emitting units U51 to U54 are determined, the magnitudes of the driving currents respectively supplied to the LED chips 503a to 503d are also determined. Accordingly, in the present modified example, the electric potential of the variable terminal of the variable resistor VR1 representing the target correlation color temperature is set as a parameter, and 8-bit data, which corresponds to the driving current values supplied to the first to fourth light emitting units U51 to U54 corresponding to various color temperatures in the range from the lower limit color temperature T1′ to the upper limit color temperature T2′, is stored as a control map in the memory M1.
When the electric potential of the variable terminal corresponding to the operation position of the color temperature adjustment dial is applied to the analog input port IP1 of the micro computer CPU1, the micro computer CPU1 acquires four pieces of 8-bit data, which represent the driving current values supplied to the first to fourth light emitting units U51 to U54 corresponding to the electric potential applied to the analog input port IP1, that is, the target correlation color temperature, from the memory M1. The micro computer CPU1 respectively associates the acquired four pieces of 8-bit data with the first to fourth light emitting units U51 to U54 and outputs them to the output ports #1 to #4. In addition, at this time, when each of the four pieces of 8-bit data is multiplied by the same reduction coefficient, it is possible to reduce the total luminous flux of the illumination light without changing the color temperature. Accordingly, in the present modified example, the acquired four pieces of 8-bit data are multiplied by the reduction coefficient of 0 to 1 for adjusting the total luminous flux, and are thereafter output to the output ports #1 to #4. Although the reduction coefficient for adjusting the total luminous flux will be described later, a description will be given below of a case where the total luminous flux is not reduced at the reduction coefficient of 1.
The output port #1 of the micro computer CPU1 is connected to the digital input port DP1 of the D/A converter DAC1. Thus, the digital signal, which is input to the digital input port DP1, is output from the analog output port AP1 after converted into the analog signal. The analog output port AP1 is connected to the non-inverting input of the operational amplifier OP1, and the output of the operational amplifier OP1 is connected to the base of the transistor Q61 corresponding to the first light emitting unit U51 as described above. Accordingly, the micro computer CPU1 outputs the 8-bit data, which represents the driving current supplied to the first light emitting unit U51, among the four pieces of 8-bit data, which are acquired from the memory M1 as described above, from the output port #1.
Likewise, the digital input port DP2 of the D/A converter DAC1, to which the output port #2 of the micro computer CPU1 is connected, corresponds to the analog output port AP2, and the analog output port AP2 is connected to the non-inverting input of the operational amplifier OP2. In addition, the output of the operational amplifier OP2 is connected to the base of the transistor Q62 corresponding to the second light emitting unit U52. Accordingly, the micro computer CPU1 outputs the 8-bit data, which represents the driving current supplied to the second light emitting unit U52, among the four pieces of 8-bit data, which are acquired from the memory M1 as described above, from the output port #2.
Further, the digital input port DP3 of the D/A converter DAC1, to which the output port #3 of the micro computer CPU1 is connected, corresponds to the analog output port AP3, and the analog output port AP3 is connected to the non-inverting input of the operational amplifier OP3. In addition, the output of the operational amplifier OP3 is connected to the base of the transistor Q63 corresponding to the third light emitting unit U53. Accordingly, the micro computer CPU1 outputs the 8-bit data, which represents the driving current supplied to the third light emitting unit U53, among the four pieces of 8-bit data, which are acquired from the memory M1 as described above, from the output port #3.
Furthermore, the digital input port DP4 of the D/A converter DAC1, to which the output port #4 of the micro computer CPU1 is connected, corresponds to the analog output port AP4, and the analog output port AP4 is connected to the non-inverting input of the operational amplifier OP4. In addition, the output of the operational amplifier OP4 is connected to the base of the transistor Q64 corresponding to the fourth light emitting unit U54. Accordingly, the micro computer CPU1 outputs the 8-bit data, which represents the driving current supplied to the fourth light emitting unit U54, among the four pieces of 8-bit data, which are acquired from the memory M1 as described above, from the output port #4.
Accordingly, from the respective four analog output ports AP1 to AP4 of the D/A converter DAC 1, in order to generate the illumination light with the target correlation color temperature which is determined by the variable resistor VR1, the analog signals with the voltage values corresponding to the driving currents to be supplied to the first to fourth light emitting units U51 to U54 are output. Then, the analog signals are respectively transmitted to the non-inverting inputs of the corresponding operational amplifiers OP1 to OP4. As described above, the output signals of the operational amplifiers OP1 to OP4 are respectively transmitted to the bases of the corresponding transistors Q61 to Q64, and currents, which correspond to the voltage values of the analog signals transmitted to the non-inverting inputs of the operational amplifiers OP1 to OP4, flow in the corresponding LED chips 503a to 503d, respectively. As a result, by synthesizing the first-order light which is emitted from each of the first to fourth light emitting units U51 to U54, it is possible to generate the illumination light with the color temperature which is set by the operation of the color temperature adjustment dial.
As described above, in the present modified example, in addition to the color temperature adjustment, it is possible to adjust the total luminous flux of the illumination light. The variable resistor VR2 in the electric circuit of
In present modified example, the target value of the total luminous flux of the illumination light is determined on the basis of the ratio of the total luminous flux to the upper limit thereof which can be obtained by the illumination apparatus. Thus, the target value is 0 in the light-off state, and the target value is 1 in the state in which the upper limit total luminous flux is obtained. In addition, when the electric potential of the variable terminal of the variable resistor VR2 is minimized, the target value is 0, and when the corresponding electric potential is maximized, the target value is 1. Further, when the electric potential of the variable terminal of the variable resistor VR2 is changed between the minimum and the maximum, in response to the electric potential, the target value of the total luminous flux is continuously changed in the range from 0 to 1.
As described above, the micro computer CPU1 multiplies the four pieces of 8-bit data by the reduction coefficient for reducing the total luminous flux of the illumination light when acquiring the four pieces of 8-bit data, which represent the driving current values supplied to the first to fourth light emitting units U51 to U54 corresponding to the target correlation color temperature, from the memory M1 and outputting them to the output ports #1 to #4. The micro computer CPU1 applies the target value of 0 to 1 determined by the electric potential of the variable terminal of the variable resistor VR2 to the reduction coefficient used herein. Accordingly, by operating the total luminous flux adjustment dial of the variable resistor VR2, it is possible to continuously adjust the total luminous flux of the illumination light in the range from the light-off state of the illumination light to the state in which the total luminous flux reaches the upper limit.
As described above, in the present modified example, in a similar manner to the above-mentioned fifth example, it is also possible to adjust the color temperature of the illumination light, and thus it is possible to obtain the same effects as the fifth example. Further, in the present modified example, in addition to the color temperature adjustment, it is possible to adjust the total luminous flux of the illumination light, whereby it is possible to generate illumination light with various color temperatures and luminances desired by a user together with the color temperature adjustment. Note that, as clearly seen from the above description of the present modified example, not only the micro computer CPU1, but also the memory M1, the D/A converter DAC1, the variable resistor VR1, and the variable resistor VR2 correspond to the control means of the present invention.
(Another Example of the Number of Light Emitting Units)
In the present example, in the XY chromaticity diagram of
For example,
As shown in
In the example of
In the case where the number of light emitting units is set to four, the chromaticity points of the light emitted by the respective light emitting units are not limited to those of the above-mentioned fifth example, and various changes may be made as necessary.
As shown in
In the example of
The number of light emitting units can also be increased to become greater than four. For example, in an example in a case where the number of light emitting units is set to five, in addition to the sixth to ninth light emitting units U56 to U59, a tenth light emitting unit U60 may further be used. In this case, in order to prevent a bias toward a specific light emitting unit from occurring due to the above-mentioned reason, for example, the chromaticity point WP10 shown in
In such a manner, by setting the chromaticity point WP10, the control curve CL is included in a pentagon which is formed such that the vertexes thereof are the chromaticity points WP6 to WP10. Further, the respective chromaticity points WP6 to WP10 are positioned outside the rectangle which is formed such that the vertexes thereof are the remaining chromaticity points. The chromaticity point WP10 is set by setting the numbers of red cells 506r, green cells 506g, yellow cells 506y, and blue cells 506b provided in the tenth light emitting unit U60.
In this case, the pentagon, which is formed such that the vertexes thereof are the five chromaticity points WP6 to WP10, also includes the control curve CL. Therefore, the intensities of the light respectively emitted from the sixth to tenth light emitting units U56 to U60 are adjusted in the same manner as the above-mentioned fifth example. Thereby, while positioning the chromaticity of the illumination light emitted from the illumination apparatus in the control curve CL, it is possible to adjust the color temperature of the illumination light in the range from the lower limit color temperature T1 to the upper limit color temperature T2. Accordingly, it is also possible to obtain the same effects as the above-mentioned illumination apparatus of the fifth example.
(Modified Example of LED Chip)
In the above-mentioned fifth example, the LED chips 503 emits the blue light with the peak wavelength of 460 nm. However, as described above, the emission wavelength characteristic and the type of the LED chip 503 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. Accordingly, for example, a description will be given below of a case of using the LED chips emitting the near-ultraviolet light with the peak wavelength of 405 nm as a modified example of the LED chip. Note that, in the case of the present modified example, in accordance with the change of the LED chip, as described later, the types of the phosphors used in the fluorescent member 505 are different from only some of the types of the fifth example, and thus the structure thereof is the same as that of the fifth example. Accordingly, the description below will be given with reference to the drawings used in the description of the fifth example.
The LED chip used in the present modified example emits the near-ultraviolet light with the peak wavelength of 405 nm, but as the LED chip, it is preferable to use a GaN LED chip in which an InGaN semiconductor is used in a light emitting layer and which emits light in the near-ultraviolet region. Further, it is preferable that the peak wavelength of the light emitted by the LED chips in the present modified example be in the wavelength range of 360 nm to 420 nm.
The cell regions 506 of the fluorescent member are divided, in a similar manner to the fifth example, into four types of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b. Each red cell 506r, each green cell 506g, and each yellow cell 506y employ the red phosphor, the green phosphor, and the yellow phosphor which respectively wavelength-convert, instead of the blue light, the near-ultraviolet light into red light, green light, and yellow light. However, as the phosphors, it may be possible to apply various phosphors exemplified in the fifth example. On the other hand, each blue cell 506b does not transmit blue light like the blue cell 506b of the fifth example, but holds the blue phosphor (fourth phosphor), which wavelength-converts the near-ultraviolet light emitted by the LED chip 503 into blue light, in a distributed manner.
An appropriate wavelength range of the emission peak wavelength of the blue phosphor is normally 420 nm or more, preferably 430 nm or more, or more preferably 440 nm or more, and normally 500 nm or less, preferably 490 nm or less, more preferably 480 nm or less, further preferably 470 nm or less, or particularly preferably 460 nm or less. From this point of view, as the blue phosphor, for example, the following are preferable: (Ca, Sr, Ba)MgAl10O17:Eu; (Sr, Ca, Ba, Mg)10(PO4)6(Cl, F)2:Eu; (Ba, Ca, Mg, Sr)2SiO4:Eu; and (Ba, Ca, Sr)3MgSi2O8:Eu. In addition, (Ba, Sr)MgAl10O17:Eu, (Ca, Sr, Ba)10O4)6(Cl, F)2:Eu, and Ba3MgSi2O8:Eu are more preferable, and Sr10(PO4)6C12:Eu and BaMgAl10O17:Eu are particularly preferable.
In addition, when the LED chips emitting the near-ultraviolet light are used, blue light transmitted through the red cells 506r, the green cells 506g, and the yellow cells 506y is reduced. Therefore, in order to compensate the reduction in blue light, the number of red cells 506r, the number of green cells 506g, the number of yellow cells 506y, and the number of blue cells 506b in the first to fourth wavelength conversion regions P51 to P54 are adjusted.
As described above, even when the LED chips emitting the near-ultraviolet light are used, if the blue cells 506b are changed in the above-mentioned manner, it is possible to generate blue light from the blue cells 506b in a similar manner to the case of the fifth example. Therefore, it is possible to emit the illumination light in the same manner as the illumination apparatus of the fifth example. In addition, by adjusting the intensity of the first-order light emitted from each light emitting unit, it is possible to obtain the same effects as the illumination apparatus of the fifth example.
(First Modified Example of Fluorescent Member)
In the above-mentioned fifth example, the fluorescent member 505 is divided into the first to fourth wavelength conversion regions P51 to P54 so as to correspond to the first to fourth light emitting units U51 to U54, and each of the wavelength conversion regions is divided into the cell regions 506 so as to correspond the respective LED chips 503. Further, the cell regions 506 are divided into four types of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b in which mutually different types of phosphors are held in a distributed manner. In addition, in each of the first to fourth wavelength conversion regions P51 to P54, the number of red cells 506r, the number of green cells 506g, the number of yellow cells 506y, and the number of blue cells 506b are set to be different. Thereby, the chromaticities of the first-order light which is respectively emitted from the first to fourth light emitting units U51 to U54 are set to be different.
However, the configuration of the fluorescent member of the fifth example is not limited to this, and may be modified into various forms. Accordingly, one thereof will be described below as a first modified example of the fluorescent member with reference to
The fluorescent member 505′ is divided, in a similar manner to the fifth example, into four wavelength conversion regions of the first wavelength conversion region P51′, the second wavelength conversion region P52′, the third wavelength conversion region P53′, and the fourth wavelength conversion region P54′. Note that, in
Accordingly, in the present modified example, the first LED group D51 and the first wavelength conversion region P51′ constitute a first light emitting unit U51′, and the second LED group D52 and the second wavelength conversion region P52′ constitute a second light emitting unit U52′. Further, the third LED group D53 and the third wavelength conversion region P53′ constitute a third light emitting unit U53′, and the fourth LED group D54 and the fourth wavelength conversion region P54′ constitute a fourth light emitting unit U54′. The light emitting section 501′, in which the four light emitting units are integrated, corresponds to the light emitting unit group of the present invention. Note that, in the description below, light, which is emitted by each of the first to fourth light emitting units U51′ to U54′, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first to fourth light emitting units U51′ to U54′ and is emitted from the light emitting section 501′, is referred to as synthetic light.
The fluorescent member 505′ has, in a similar manner to the fluorescent member 505 of the fifth example, a function of converting the wavelength of the light emitted by the LED chips 503 for each wavelength conversion region and emitting light with a peak wavelength different from the light emitted by the LED chips 503. However, the fluorescent member 505′ is not divided into cell regions, where the phosphors are uniformly distributed and held in each wavelength conversion region. Specifically, in the fluorescent member 505′ of the present modified example, the red phosphor, the green phosphor, and the yellow phosphor are used in a mixed manner. Therefore, instead of adjusting the number of red cells 506r, the number of green cells 506g, the number of yellow cells 506y, and the number of blue cells 506b through each wavelength conversion region in the same manner as the fifth example, the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor is changed for each wavelength conversion region.
More specifically, as shown in
Note that, as shown in
As described above, with such a configuration of the first to fourth wavelength conversion regions P51′ to P54′ of the fluorescent member 505′, the first-order light emitted from each of the first to fourth light emitting units U51′ to U54′ has each chromaticity of the chromaticity points WP1 to WP4 in the XY chromaticity diagram of
Note that, in the present modified example, instead of the LED chips emitting the blue light, it may be possible to use the LED chips emitting the near-ultraviolet light. In this case, in addition to the red phosphor, the green phosphor, and the yellow phosphor used in the fluorescent member 505′, the blue phosphor, which converts the wavelength of the near-ultraviolet light emitted by the LED chips so as to emit blue light, may be used in a mixed manner.
(Second Modified Example of Fluorescent Member)
A further modified example of the fluorescent member will be described as a second modified example with reference to
In the present modified example, the basic configuration of the light emitting section is also the same as that of the fifth example, and only the division of the fluorescent member provided in the transparent board 504 is different from the fifth example or the first modified example. Specifically, in a similar manner to the fifth example, also in the present modified example, the fluorescent member is divided into 160 cell regions 506″ respectively corresponding to the LED chips 503. However, the configuration of each cell region 506″ is different from the cell region 506 of the fifth example.
That is, also in the present modified example, in a similar manner to the fifth example, the fluorescent member is divided into four wavelength conversion regions of the first wavelength conversion region, the second wavelength conversion region, the third wavelength conversion region, and the fourth wavelength conversion region, and each wavelength conversion region includes 40 cell regions 506″. In the fifth example, the 160 cell regions 506 are divided into four type cell regions of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b. In each wavelength conversion region, the number of red cells 506r, the number of green cells 506g, the number of yellow cells 506y, and the number of blue cells 506b are different.
In contrast, in the present modified example, each cell region 506″ is further divided into four regions of a red region 520r, a green region 520g, a yellow region 520y, and a blue region 520b. In the red regions 520r, the red phosphors, which are for emitting red light by converting the wavelength of the blue light emitted by the LED chips 503, are held in a distributed manner. In the green regions 520g, the green phosphors, which are for emitting green light by converting the wavelength of the blue light emitted by the LED chips 503, are held in a distributed manner. In the yellow regions 520y, the yellow phosphors, which are for emitting yellow light by converting the wavelength of the blue light emitted by the LED chips 503, are held in a distributed manner. In addition, in each blue region 520b, in a similar manner to the blue cell 506b of the fifth example, the diffusing particles for satisfactorily diffusing and emitting blue light are held in a distributed manner in the cell region which transmits the blue light emitted by the LED chip 503 without wavelength conversion.
Specifically, as shown in
Note that, as shown in
As described above, with such a configuration of the cell regions 506″ included in each wavelength conversion region, the first-order light emitted from each light emitting unit has each chromaticity of the chromaticity points WP1 to WP4 in the XY chromaticity diagram of
Note that, in the present modified example, instead of the LED chips emitting the blue light, it may be possible to use the LED chips emitting the near-ultraviolet light. In this case, in the blue region 520b of the cell region 506″, it is preferable that the blue phosphor, which converts the wavelength of the near-ultraviolet light emitted by the LED chip so as to emit blue light, be held in a distributed manner. However, when the LED chips emitting the near-ultraviolet light are used, blue light transmitted through the red regions 520r, the green regions 520g, and the yellow regions 520y is reduced. Therefore, in order to compensate the reduction in blue light, the areas of the red region 520r, the green region 520g, the yellow region 520y, and the blue region 520b of each cell region 506″ are adjusted for each wavelength conversion region.
(Third Modified Example of Fluorescent Member)
In the fifth example, the fluorescent member 505 is divided into four parts, that is, the first to fourth wavelength conversion regions P51 to P54, and together with the LED chips 503 grouped into the first to fourth LED groups D51 to D54 corresponding to the wavelength conversion regions, the first to fourth light emitting units U51 to U54 are formed one by one. However, at least one of the first to fourth wavelength conversion regions P51 to P54 may be further divided.
In accordance with the division of the wavelength conversion regions, the first LED group D51 is also divided into two parts, and they are disposed with the second LED group D52 interposed therebetween. Likewise, the third LED group D53 is also divided into two parts, and they are disposed with the fourth LED group D54 interposed therebetween. As a result, the first light emitting unit U51 formed of the first LED group D51 and the first wavelength conversion region P51 is also divided into two parts, and they are disposed with the second light emitting unit U52 interposed therebetween. Further, the third light emitting unit U53 formed of the third LED group D53 and the third wavelength conversion region P53 is also divided into two parts, and they are disposed with the fourth light emitting unit U54 interposed therebetween. Note that, in this case, the light emitting section 501″ formed of the first to fourth light emitting units U51 to U54 corresponds to the light emitting unit group of the present invention.
In the first wavelength conversion region P51 divided into two parts, the total number of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b is the same as that of the first wavelength conversion region P51 of the fifth example. In the third wavelength conversion region P53 divided into two parts, the total number of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b is the same as that of the third wavelength conversion region P53 of the fifth example. Accordingly, by adjusting the intensity of the first-order light emitted from each light emitting unit in a similar manner to the case of the fifth example, the illumination light of the illumination apparatus of the present modified example can be adjusted in the color temperature range from the lower limit color temperature T1 to the upper limit color temperature T2 at the chromaticity in the control curve CL shown in
Furthermore, since each of the first wavelength conversion region P51 and the third wavelength conversion region P53 is divided into two parts so as to be disposed in a distributed manner, it is possible to more satisfactorily synthesize the first-order light emitted from each wavelength conversion region. Note that, in the present modified example, each of the first wavelength conversion region P51 and the third wavelength conversion region P53 is divided into two parts, but the divided wavelength conversion regions are not limited to them, and at least one of the first to fourth wavelength conversion regions P51 to P54 may be divided in the same manner. Further, the number of divided parts is also not limited to two, may be three or more. Furthermore, the arrangement of the wavelength conversion regions is also not limited to the form of
In the present modified example, each wavelength conversion region is further divided into cell regions in a similar manner to the fifth example, but the present modified example can also be applied to the first modified example shown in
(First Modified Example of Emission Control)
In the fifth example, by setting the target correlation color temperature in accordance with the operation position of the operation dial 514a of the operation unit 514, the emission control for controlling light emission of the first to fourth light emitting units U51 to U54 is performed such that the color temperature of the illumination light of the illumination apparatus (light emission apparatus 1) is the target correlation color temperature. At this time, particularly in the color temperature region less than or equal to 4000 K, as shown in
Accordingly, instead of adjusting the color temperature in accordance with the operation performed on the operation unit 514 in the same manner as the fifth example, it is possible to adjust the total luminous flux of the illumination light of the illumination apparatus in the range from the light-off state to the maximum total luminous flux state. Further, in a similar manner to the description of the emission control of the fifth example, when the on/off control of the transistors Q51 to Q54 is performed on the basis of the relationship shown in
As shown in
The change in the color temperature and the total luminous flux of the illumination light can be achieved by changing the magnitudes of the electric powers respectively supplied to the first to fourth light emitting units U51 to U54 from the magnitudes thereof shown in
The main body 514b′ of the operation unit 514′ detects the position of the operation dial 514a′, and notifies the detected position of the operation dial 514a′ to the target value setting section 515 in a similar manner to the fifth example. The target value setting section 515 determines the target total luminous flux corresponding to the detected position of the operation dial 514a′, on the basis of the relationship between the target total luminous flux and the position of the operation dial 514a′ which is set in advance to match with the indication on the main body 514b′ of the operation unit 514′, and transmits the target total luminous flux to the emission control section 513. In addition, since the relationship shown in
The emission control section 513 acquires the amount of on/off control of each of the transistors Q51 to Q54 corresponding to the target total luminous flux, which is sent from the target value setting section 515, from the control map stored in the memory 513a, and controls on and off states of the transistors Q51 to Q54 on the basis of the acquired amount of control. As a result, the illumination light of the total luminous flux corresponding to the position of the operation dial 514a of the operation unit 514′ is emitted from the illumination apparatus.
As shown in
Further, Literature Kruithof A A: Tubular Luminescence Lamps for General Illumination, Philips Technical Review, 6, pp. 65-96 (1941) describes the illuminance at which a human feels comfortable when the color temperature of the synthetic white light is changed. On the basis of this Literature (hereinafter referred to as Kruithof Literature), if the color temperature of the synthetic white light is intended to be changed while comfort is maintained, it is preferable to control light emission of the light emitting unit at the time of changing the target luminous flux φ in accordance with the target correlation color temperature T such that such that the constant A0, at which the following inequality expression (1) is established, is present.
−80743−(1000/T)5+164973−(1000/T)4−135260−(1000/T)3+57994−(1000/T)2−13995−(1000/T)+1632.9<φ/A0<exp{−342.11−(1000/T)3+450.43−(1000/T)2−212.19×(1000/T)+39.47}. (1)
In the above-mentioned fifth example, the illuminance of the irradiated surface (that is, the irradiated object which is irradiated with light by the illumination apparatus), which faces the fronts of the light emitting section 501 and is positioned at the distance R, is φ/(π·R2). Here, it is assumed that the light distribution of the light emission apparatus is Lambertian. When N light emission apparatuses are provided (that is, when the illuminance of the above-mentioned irradiated object is N·φ/(π·R2)), by substituting A0=π·R2·N into the inequality expression (1), it is possible to calculate the target luminous flux appropriate for the target correlation color temperature T. For example, when R is set to 2m and N is set to 12, as shown in the table of
By performing such emission control, the color temperature and the total luminous flux of the illumination light emitted from the illumination apparatus are changed in accordance with the relationship indicated by the solid line of
Further,
In
As described above, in both of the case where the target correlation color temperature T is set and thereby the target total luminous flux φ is set (the case of the present example) and the case where the target total luminous flux φ is set and thereby the target correlation color temperature T is set (in the case of the modified example), in the entire set color temperature range, it is possible to obtain an appropriate illuminance. Thus, even in the case where the color temperature of the light emitted from the illumination apparatus is changed, it is possible to provide light which is comfortable all the time.
(Second Modified Example of Emission Control)
In the fifth example, the target correlation color temperature is determined in accordance with the operation performed on the operation unit 514, the amount of control corresponding to the target correlation color temperature is acquired from the control map which is stored in advance, and the on/off control of the transistors Q51 to Q54 is performed. In such a manner, it is possible to reduce the computation load of the emission control section 513. However, in such a case where there is a room for computation capability of the emission control section 513, the amount of control corresponding to the set target correlation color temperature may be computed without using such a control map in each case. In this case, it is possible to reduce the amount of data occupying the memory 513a provided on the emission control section 513.
(Third Modified Example of Emission Control)
In the fifth example, the color temperature of the illumination light can be changed in accordance with the operation performed on the operation unit 514, but instead of user's operation, the total luminous flux and the color temperature of the illumination light are changed in accordance with the pattern which is set in advance. In this case, the amount of control (the amount of emission control), which corresponds to the pattern of the change in the total luminous flux or the change in the color temperature of the illumination light with the passage of time, is stored in advance in the memory 513a of the emission control section 513, and the transistors Q51 to Q54 may be controlled on the basis of the amount of control acquired in accordance with the time count of the timer built in the emission control section 513. Further, instead of the pattern which is set in advance, by detecting environment using the illumination apparatus such as temperature, humidity, a season, or a place of use or a purpose of use of the illumination apparatus, the total luminous flux and the color temperature of the illumination light may be changed in accordance with the detected environment.
(Fourth Modified Example of Emission Control)
In the fifth example, the target correlation color temperature is determined in accordance with the operation performed on the operation unit 514, the corresponding amount of control is determined on the basis of the target correlation color temperature, and the transistors Q51 to Q54 is controlled. However, in accordance with the operation performed on the operation unit 514, the amount of control (the amount of emission control) may be directly determined. In this case, in a similar manner to the fifth example, the amount of control is determined on the basis of the relation shown in
In the fifth example mentioned above, the illumination apparatus is configured by using the light emitting unit groups each including the plurality of LED chips 503 mounted on the wiring board 502 and the fluorescent member 505 provided on the transparent board 504. However, the illumination apparatus according to the present invention is not limited to such a form, and may be modified into or replaced with various forms without departing from the technical scope of the present invention. Accordingly, an example of the illumination apparatus, which is configured by using light emitting unit groups different from the light emitting unit groups of the fifth example, will be described below as a sixth example of the present invention.
(Configuration of Light Emitting Section)
The inside of the reflector 604 is partitioned by the partition member 605 into a first region 606 and a second region 607. In the first region 606, the LED chips 603, which belong to one of the two arrays of the LED chips 603, are disposed. In the second region 607, the LED chips 603, which belong to the other array, are disposed. In addition, the reflector 604 and the partition member 605 can be formed of resin, metal, ceramic, or the like, and is fixed onto the wiring board 602 through an adhesive or the like. Further, when a conductive material is used in the reflector 604 and the partition member 605, a process for providing electrical insulation to a wiring pattern to be described later is necessary.
Note that, in the present example, the number of LED chips 603 is just an example, may be increased or decreased as necessary, may be one for each of the first region 606 and the second region 607, and may be different for each region. Further, the material of the wiring board 602 is not limited to the alumina ceramic, and may use various kinds of materials. For example, it may be possible to use a material selected from ceramic, resin, glass epoxy, and composite resin containing a filler as materials with excellent electrical insulation. Furthermore, in order to improve a light emitting efficiency of the light emitting section 601 by enhancing reflectivity of light on the chip mounting surface 602a of the wiring board 602, it is preferable to use silicon resin including a white pigment such as alumina powder, silica powder, magnesium oxide, or titanium oxide. On the other hand, by using a substrate made of metal such as copper or aluminum, it is possible to improve a heat dissipation ability. However, in this case, it is necessary to form the wiring patterns on the wiring board with electrical insulation performed thereon.
Further, the shapes of the above-mentioned reflector 604 and partition member 605 are also just exemplary shapes, may be modified into various shapes as necessary. For example, instead of the reflector 604 and the partition member 605 formed in advance, an annular wall portion (wall member) corresponding to the reflector 604 may be formed on the chip mounting surface 602a of the wiring board 602 by using a dispenser or the like, and thereafter a partition wall (partition member) corresponding to the partition member 605 may be formed. In this case, the material used in the annular wall portion and the partition wall portion is, for example, a UV curable resin material or a thermosetting resin material having a paste form, and thus silicon resin containing an inorganic filter is appropriate therefor.
As shown in
The wiring patterns 608, 609, 610, and 611 for respectively supplying driving currents to the LED chips 603 are formed on the chip mounting surface 602a of the wiring board 602, as shown in
The four LED chips 603 inside the first region 606 are connected in parallel between the wiring pattern 608 and the wiring pattern 609, which are formed as described above, such that the directions of polarities thereof are the same. More specifically, the LED chip 603 has two electrodes (not shown in the drawing) for supplying driving currents on the surface of the wiring board 602 side. In addition, one electrode (p electrode) of the LED chip 603 is connected to the wiring pattern 608, and the other electrode (n electrode) thereof is connected to the wiring pattern 609.
On the other hand, a connection terminal 610a for external connection is formed at one end of the wiring pattern 610 outside the reflector 604, and the other end side of the pattern inside the second region 607 is provided to extend in parallel with the partition member 605 as shown in
The four LED chips 603 inside the second region 607 are connected in parallel between the wiring pattern 610 and the wiring pattern 611, which are formed as described above, such that the directions of polarities thereof are the same. More specifically, one electrode (p electrode) of the LED chip 603 is connected to the wiring pattern 610, and the other electrode (n electrode) thereof is connected to the wiring pattern 611.
By using flip chip mounting, the LED chips 603 are mounted and both electrodes are connected to the respective wiring patterns with an unillustrated metal bump interposed therebetween through the eutectic solder. Note that, the method of mounting the LED chips 603 on the wiring board 602 is not limited to this, and it may be possible to select a method appropriate for the type, the structure, or the like of the LED chips 603. For example, it may be possible to employ double wire bonding which connects the electrodes of the LED chips 603 to the corresponding wiring patterns through wire bonding after the LED chips 603 are fixedly attached to predetermined positions of the wiring board 602 mentioned above. In addition, it may be possible to employ single wire bonding which bonds one electrode to the wiring pattern as described above and connects the other electrode to the wiring pattern through the wire bonding.
The first region 606 and the second region 607 inside the reflector 604 house fluorescent members (wavelength conversion members) respectively having different wavelength conversion characteristics such that the fluorescent members cover the LED chips 603. The present example employs four types of the fluorescent members, and employs two types of light emitting sections of a light emitting section containing the two types of the fluorescent members thereof and a light emitting section containing the remaining two types of the fluorescent members thereof. Accordingly, in the description below, one light emitting section is referred to as a first light emitting section 601A, and the other light emitting section is referred to as a second light emitting section 601B.
The first light emitting section 601A and the second light emitting section 601B have the same structure mentioned above except the fluorescent members, and all the LED chips 603 also have the same type. Here, for convenience of description, regarding the first light emitting section 601A, the reference sign 603a is assigned to each LED chip positioned in the first region 606, and the reference sign 603b is assigned to each LED chip positioned in the second region 607. Further, regarding the second light emitting section 601B, the reference sign 603c is assigned to each LED chip positioned in the first region 606, and the reference sign 603d is assigned to each LED chip positioned in the second region 607. The respective members other than the fluorescent members and the LED chips are represented by common reference signs and numerals in the first light emitting section 601A and the second light emitting section 601B.
The first fluorescent member 612a is excited by the light emitted by the LED chips 603a, and is formed of a first phosphor 613, which emits light with a wavelength different from that of the light emitted by the LED chips 603a, and a first filler 614 for holding the first phosphor 613 in a distributed manner. Further, the second fluorescent member 612b is excited by the light emitted by the LED chips 603b, and is formed of a second phosphor 615, which emits light with a wavelength different from that of the light emitted by the LED chips 603b, and a second filler 616 for holding the second phosphor 615 in a distributed manner.
The third fluorescent member 617 is excited by the light emitted by the LED chips 603c, and is formed of a third phosphor 619, which emits light with a wavelength different from that of the light emitted by the LED chips 603c, and a third filler 620 for holding the third phosphor 619 in a distributed manner. Further, the fourth fluorescent member 618 is excited by the light emitted by the LED chips 603d, and is formed of a fourth phosphor 621, which emits light with a wavelength different from that of the light emitted by the LED chips 603d, and a fourth filler 622 for holding the fourth phosphor 621 in a distributed manner.
Accordingly, in the present example, the respective combinations of the first fluorescent member 612a, the second fluorescent member 612b, the third fluorescent member 617, and the fourth fluorescent member 618 and the LED chips 603a, 603b, 603c, and 603d, which are used to correspond thereto, correspond to the respective light emitting units of the present invention. That is, the LED chips 603a and the first fluorescent member 612a constitute a first light emitting unit U601, and the LED chips 603b and the second fluorescent member 612b constitute a second light emitting unit U602. In addition, the LED chips 603c and the third fluorescent member 617 constitute a third light emitting unit U603, and the LED chips 603d and the fourth fluorescent member 618 constitute a fourth light emitting unit U604. Further, integrated one of the four types of the light emitting units corresponds to the light emitting unit group of the present invention. Note that, in the description below, light, which is emitted by each of the first to fourth light emitting units U601 to U604, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first to fourth light emitting units U601 to U604 and is emitted from the first light emitting section 601A and the second light emitting section 601B, is referred to as synthetic light.
(LED Chip)
As the LED chips 603a, 603b, 603c, and 603d, in the present example, the LED chips emitting the blue light with a peak wavelength of 460 nm are used. Specifically, as such an LED chip, there is a GaN LED chip in which for example an InGaN semiconductor is used in a light emitting layer. Note that, the emission wavelength characteristic and the type of the LED chip 603 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. In the present example, it is preferable that the peak wavelengths of the light emitted by the LED chips 603a, 603b, 603c, and 603d be in the wavelength range of 420 nm to 500 nm.
(Fluorescent Member)
In a similar manner to the first wavelength conversion region P51 of the fluorescent member 505 of the fifth example, the first fluorescent member 612a is configured to emit the first-order light with the chromaticity of the chromaticity point WP1 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 603a is converted by the red phosphor, the green phosphor, and the yellow phosphor included in the first fluorescent member 612a, and red light, green light, and yellow light are emitted from the first fluorescent member 612a. At this time, the blue light, which is emitted from the LED chip 603a and transmitted through the first fluorescent member 612a without wavelength conversion performed by the first fluorescent member 612a, is emitted from the first fluorescent member 612a together with the red light, the green light, and the yellow light. Accordingly, the first-order light, in which the red light, the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the first light emitting unit U601.
In the first fluorescent member 612a, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor of the first filler 614 are determined on the basis of, as shown in
In a similar manner to the second wavelength conversion region P52 of the fluorescent member 505 of the first example, the second fluorescent member 612b is configured to emit the first-order light with the chromaticity of the chromaticity point WP2 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 603b is converted by the green phosphor and the yellow phosphor included in the second fluorescent member 612b, and green light and yellow light are emitted from the second fluorescent member 612b. At this time, the blue light, which is emitted from the LED chip 603b and transmitted through the second fluorescent member 612b without wavelength conversion performed by the second fluorescent member 612b, is emitted from the second fluorescent member 612b together with the green light and the yellow light. Accordingly, the first-order light, in which the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the second light emitting unit U602.
In the second fluorescent member 612b, the densities and the mixture ratio of the green phosphor and the yellow phosphor of the second filler 616 are determined on the basis of, as shown in
In a similar manner to the third wavelength conversion region P53 of the fluorescent member 505 of the fifth example, the third fluorescent member 617 is configured to emit the first-order light with the chromaticity of the chromaticity point WP3 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 603c is converted by the red phosphor, the green phosphor, and the yellow phosphor included in the third fluorescent member 617, and red light, green light, and yellow light are emitted from the third fluorescent member 617. At this time, the blue light, which is emitted from the LED chip 603c and transmitted through the third fluorescent member 617 without wavelength conversion performed by the third fluorescent member 617, is emitted from the third fluorescent member 617 together with the red light, the green light, and the yellow light. Accordingly, the first-order light, in which the red light, the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the third light emitting unit U603.
In the third fluorescent member 617, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor of the third filler 620 are determined on the basis of, as shown in
In a similar manner to the fourth wavelength conversion region P54 of the fluorescent member 505 of the fifth example, the fourth fluorescent member 618 is configured to emit the first-order light with the chromaticity of the chromaticity point WP4 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 603d is converted by the red phosphor, the green phosphor, and the yellow phosphor included in the fourth fluorescent member 618, and red light, green light, and yellow light are emitted from the fourth fluorescent member 618. At this time, the blue light, which is emitted from the LED chip 603d and transmitted through the fourth fluorescent member 618 without wavelength conversion performed by the fourth fluorescent member 618, is emitted from the fourth fluorescent member 618 together with the red light, the green light, and the yellow light. Accordingly, the first-order light, in which the red light, the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the fourth light emitting unit U604.
In the fourth fluorescent member 618, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor of the fourth filler 622 are determined on the basis of, as shown in
(Electric Circuit Configuration of Illumination Apparatus)
In the illumination apparatus of the present example, at least one of each of the first to fourth light emitting units U601 to U604 is necessary. Thus, at least one first light emitting section 601A and at least one second light emitting section 601B are used in combination in the illumination apparatus. In addition, in a similar manner to the fifth example, the synthetic light, which is generated by synthesizing the first-order light emitted from each of the first to fourth light emitting units U601 to U604, is emitted as the illumination light of the illumination apparatus. Accordingly, by adjusting the intensity of the first-order light, which is emitted from each of the first to fourth light emitting units U601 to U604, in a similar manner to the fifth example, it is possible to emit white light with various color temperatures as the illumination light. Referring to
In the first light emitting section 601A, the LED chips 603a and 603b are mounted on the wiring board 602 as described above. Thereby, the LED chips 603a are connected to one another in parallel, the anode thereof is connected to the connection terminal 608a, and the cathode thereof is connected to the connection terminal 609a. Further, the LED chips 603b are connected to one another in parallel, the anode thereof is connected to the connection terminal 610a, and the cathode thereof is connected to the connection terminal 611a.
In a similar manner to the first light emitting section 601A, in the second light emitting section 601B, the LED chips 603c are connected to one another in parallel, the anode thereof is connected to the connection terminal 608a, and the cathode thereof is connected to the connection terminal 609a. Further, the LED chips 603d are connected to one another in parallel, the anode thereof is connected to the connection terminal 610a, and the cathode thereof is connected to the connection terminal 611a.
In the first light emitting section 601A, the connection terminal 608a is connected to the positive terminal of the power supply 623 through the resistor R11, and the connection terminal 609a is connected to the collector of the transistor Q611. Further, the connection terminal 610a is connected to the positive terminal of the power supply 623 through R12, and the connection terminal 611a is connected to the collector of the transistor Q612. On the other hand, in the second light emitting section 601B, the connection terminal 608a is connected to the positive terminal of the power supply 623 through the resistor R13, and the connection terminal 609a is connected to the collector of the transistor Q613. Further, the connection terminal 610a is connected to the positive terminal of the power supply 623 through R14, and the connection terminal 611a is connected to the collector of the transistor Q614. In addition, each emitter of the transistors Q611 to 614 is connected to the negative terminal of the power supply 623.
In such an electric circuit configuration, by turning on the transistor Q611, forward currents supplied from the power supply 623 flow in the respective LED chips 603a of the first light emitting section 601A, and thereby the LED chips 603a respectively emit light. Accordingly, by turning on the transistor Q611, the first light emitting unit U601, which is formed of the LED chips 603a and the first fluorescent member 612a, emits the first-order light with the chromaticity of the chromaticity point WP1 in the XY chromaticity diagram of
Likewise, by turning on the transistor Q612, forward currents supplied from the power supply 623 flow in the respective LED chips 603b of the first light emitting section 601A, and thereby the LED chips 603b respectively emit light. Accordingly, by turning on the transistor Q612, the second light emitting unit U602, which is formed of the LED chips 603b and the second fluorescent member 612b, emits the first-order light with the chromaticity of the chromaticity point WP2 in the XY chromaticity diagram of
Further, by turning on the transistor Q613, forward currents supplied from the power supply 623 flow in the respective LED chips 603c of the second light emitting section 601B, and thereby the LED chips 603c respectively emit light. Accordingly, by turning on the transistor Q613, the third light emitting unit U603, which is formed of the LED chips 603c and the third fluorescent member 617, emits the first-order light with the chromaticity of the chromaticity point WP3 in the XY chromaticity diagram of
Furthermore, by turning on the transistor Q614, forward currents supplied from the power supply 623 flow in the respective LED chips 603d of the second light emitting section 601B, and thereby the LED chips 603d respectively emit light. Accordingly, by turning on the transistor Q614, the fourth light emitting unit U604, which is formed of the LED chips 603d and the fourth fluorescent member 618, emits the first-order light with the chromaticity of the chromaticity point WP4 in the XY chromaticity diagram of
In order to control on/off states of the transistors Q611 to Q614, the illumination apparatus of the present example is provided with an emission control section 624. All the transistors Q611 to Q614 are able to switch the on/off states in response to the respective base signals, and the emission control section 624 is configured to individually transmit the base signals to the respective bases. The emission control section 624 has practically the same configuration as the emission control section 513 of the fifth example, and thus performs the same emission control as the emission control section 513.
Hence, the emission control section 624 has own memory (storage device) 624a used in storing information necessary for the emission control and the like. Further, in a similar manner to the case of the fifth example, the illumination apparatus of the present example is also provided with an operation unit (operation member) 625 by which a user sets the total luminous flux or the color temperature of the illumination light, and a target value setting section 626 that sets the target correlation color temperature or the target total luminous flux in accordance with the operation performed on the operation unit 625. In the present example, the emission control section 624, the operation unit 625, and the target value setting section 626 constitute the control means of the present invention.
The emission control section 624 performs the emission control in the same manner as the case of the fifth example. Thereby, in the illumination apparatus of the present example, it is also possible to generate illumination light the same as that of the illumination apparatus of the fifth example. Accordingly, it is possible to change the color temperature of the illumination light emitted from the illumination apparatus in the range from the lower limit color temperature T1 to the upper limit color temperature T2. At this time, the chromaticity of the illumination light is approximate to the black-body radiation locus BL. As a result, it is possible to make the illumination light be white light which is natural without sense of discomfort.
Note that, in the present example, the electric circuit of the illumination apparatus is also not limited to the configuration shown in
(Arrangement Example of Light Emitting Section)
In the electric circuit configuration of
(Modified Example of Light Emitting Section)
Further, in the present example, the first light emitting unit U601 and the second light emitting unit U602 are formed in the first light emitting section 601A, and the third light emitting unit U603 and the fourth light emitting unit U604 are formed in the second light emitting section 601B. However, the combination of the light emitting units is not limited to this, and the four types of the light emitting units may be arbitrarily combined into two pairs. Furthermore, the combination of four types of the light emitting units is not limited to the two groups of the first light emitting section 601A and the second light emitting section 601B in a similar manner to the present example, and a different combination may be used, and three or more light emitting sections may be used.
Note that, in the present example, instead of the LED chips emitting the blue light, it may be possible to use the LED chips emitting the near-ultraviolet light. In this case, in order to generate the blue light, in addition to the red phosphor, the green phosphor, and the yellow phosphor used in the present example, the blue phosphor, which converts the wavelength of the near-ultraviolet light emitted by the LED chips so as to emit blue light, may be used. In this case, instead of the blue light respectively emitted through the first fluorescent member 612a, the second fluorescent member 612b, the third fluorescent member 617, and the fourth fluorescent member 618, the blue light emitted from the blue phosphor is used. Therefore, in view of this point, it is preferable to adjust the densities and the content percentages of the phosphors in the fluorescent members.
Further, in the case of using the LED chips emitting the near-ultraviolet light, it is preferable to use a material, which has durability and transparency sufficient for the near-ultraviolet light emitted by the LED chips, in the first filler 614, the second filler 616, the third filler 620, and the fourth filler 622 respectively used in the first fluorescent member 612a, the second fluorescent member 612b, the third fluorescent member 617, and the fourth fluorescent member 618. Specifically, for example, examples of the fillers include: an (meth)acryl resin such as poly(meth)acrylate methyl; a styrene resin such as polystyrene or styrene-acrylonitrile copolymer; a polycarbonate resin; a polyester resin; a phenoxy resin; a butyral resin; polyvinyl alcohol; a cellulosic resin such as ethyl cellulose, cellulose acetate, or cellulose acetate butyrate; an epoxy resin; a phenol resin; and a silicon resin. Further, it may be possible to use an inorganic material such as metal alkoxide, ceramic precursor polymer, a solution which is obtained by hydrolytically polymerizing a solution containing metal alkoxide, or an inorganic material, in which such a combination is solidified, such as an inorganic material having a siloxane bond or glass.
As described above, in the present example and modified example thereof, the light emitting unit group is formed of the light emitting sections each of which has two light emitting units integrally formed. Therefore, it becomes easy to treat the light emitting unit group, and it is possible to reduce the manufacturing costs and the number of manufacturing processes of the illumination apparatus.
In the above-mentioned sixth example, the illumination apparatus is configured by using the light emitting unit groups in which the first light emitting section 601A and the second light emitting section 601B each of which is formed of two light emitting units are combined. However, the light emitting units formed in the first light emitting section 601A and the second light emitting section 601B can be integrated. Accordingly, an example of the illumination apparatus, which is configured by integrating the light emitting units which are formed in the same manner as the light emitting units of the sixth example, will be described below as a seventh example of the present invention.
(Configuration of Light Emitting Section)
A reflector (wall member) 704, which is similar to the reflector 604 of the sixth example and has an annular and truncated cone shape, is provided on the chip mounting surface 702a of the wiring board 702 so as to surround the LED chips 703a to 703d. The partition member 705 having a cross-shape partitions the inside of the reflector 704 into four regions of a first region 706, a second region 707, a third region 708, and a fourth region 709. Note that, in
In a similar manner to the reflector 604 and the partition member 605 of the sixth example, the reflector 704 and the partition member 705 can be formed of resin, metal, ceramic, or the like, and is fixed onto the wiring board 702 through an adhesive or the like. Further, when a conductive material is used in the reflector 704 and the partition member 705, a process for providing electrical insulation to a wiring pattern to be described later is necessary.
Note that, in the present example, the number of each of the LED chips 703a to 703d is just an example, may be increased or decreased as necessary, may be one for each of the first to fourth regions 706 to 709, and may be different for each region. Further, the material of the wiring board 702 is not limited to the alumina ceramic, and may use various kinds of materials. For example, it may be possible to use a material selected from ceramic, resin, glass epoxy, and composite resin containing a filler as materials with excellent electrical insulation. Furthermore, in order to improve a light emitting efficiency of the light emitting section 701 by enhancing reflectivity of light on the chip mounting surface 702a of the wiring board 702, it is preferable to use silicon resin including a white pigment such as alumina powder, silica powder, magnesium oxide, or titanium oxide. On the other hand, by using a substrate made of metal such as copper or aluminum, it is possible to improve a heat dissipation ability. However, in this case, it is necessary to form the wiring patterns on the wiring board with electrical insulation performed thereon.
Further, the shapes of the above-mentioned reflector 704 and partition member 705 are also just exemplary shapes, may be modified into various shapes as necessary. For example, instead of the reflector 704 and the partition member 705 formed in advance, an annular wall portion (wall member) corresponding to the reflector 704 may be formed on the chip mounting surface 702a of the wiring board 702 by using a dispenser or the like, and thereafter a partition wall (partition member) corresponding to the partition member 705 may be formed. In this case, the material used in the annular wall portion and the partition wall portion is, for example, a UV curable resin material or a thermosetting resin material having a paste form, and thus silicon resin containing an inorganic filter is appropriate therefor.
The wiring patterns 710, 711, 712, 713, 714, 715, 716, and 717 for respectively supplying driving currents to the LED chips 703a, 703b, 703c, and 703d are formed on the chip mounting surface 702a of the wiring board 702, as shown in
The four LED chips 703a inside the first region 706 are connected in parallel between the wiring pattern 710 and the wiring pattern 711 in the first region 706 such that the directions of polarities thereof are the same. More specifically, the LED chip 703a has two electrodes (not shown in the drawing) for supplying driving currents on the surface of the wiring board 702 side. In addition, one electrode (p electrode) of the LED chip 703a is connected to the wiring pattern 710, and the other electrode (n electrode) thereof is connected to the wiring pattern 711.
Likewise, the four LED chips 703b inside the second region 707 are connected in parallel between the wiring pattern 712 and the wiring pattern 713 in the second region 707 such that the directions of polarities thereof are the same. More specifically, the LED chip 703b has two electrodes (not shown in the drawing) for supplying driving currents on the surface of the wiring board 702 side. In addition, one electrode (p electrode) of the LED chip 703b is connected to the wiring pattern 712, and the other electrode (n electrode) thereof is connected to the wiring pattern 713.
Furthermore, the four LED chips 703c inside the third region 708 are connected in parallel between the wiring pattern 714 and the wiring pattern 715 in the third region 708 such that the directions of polarities thereof are the same. More specifically, the LED chip 703c has two electrodes (not shown in the drawing) for supplying driving currents on the surface of the wiring board 702 side. In addition, one electrode (p electrode) of the LED chip 703c is connected to the wiring pattern 714, and the other electrode (n electrode) thereof is connected to the wiring pattern 715.
Further, the four LED chips 703d inside the fourth region 709 are connected in parallel between the wiring pattern 716 and the wiring pattern 717 in the fourth region 709 such that the directions of polarities thereof are the same. More specifically, the LED chip 703d has two electrodes (not shown in the drawing) for supplying driving currents on the surface of the wiring board 702 side. In addition, one electrode (p electrode) of the LED chip 703d is connected to the wiring pattern 716, and the other electrode (n electrode) thereof is connected to the wiring pattern 717.
By using flip chip mounting, the LED chips 703a to 703d are mounted and both electrodes are connected to the respective wiring patterns with an unillustrated metal bump interposed therebetween through the eutectic solder. Note that, the method of mounting the LED chips 703a to 703d on the wiring board 702 is not limited to this, and it may be possible to select a method appropriate for the type, the structure, or the like of the LED chips 703a to 703d. For example, it may be possible to employ double wire bonding which connects the electrodes of the LED chips 703a to 703d to the corresponding wiring patterns through wire bonding after the LED chips 703a to 703d are fixedly attached to predetermined positions of the wiring board 702 mentioned above. In addition, it may be possible to employ single wire bonding which bonds one electrode to the wiring pattern as described above and connects the other electrode to the wiring pattern through the wire bonding.
As shown in
Further, as shown in
Furthermore, as shown in
Further, as shown in
As described above, in the present example, the four first to fourth light emitting units U701 to U704 are integrally provided, and the light emitting section 701, which has the first to fourth light emitting units U701 to U704, forms the light emitting unit group of the present invention. Note that, in the description below, light, which is emitted by each of the first to fourth light emitting units U701 to U704, is referred to as first-order light, and light, which is formed by synthesizing the first-order light emitted by each of the first to fourth light emitting units U701 to U704 and is emitted from the light emitting section 701, is referred to as synthetic light.
(LED Chip)
As the LED chips 703a to 703d, in the present example, the LED chips emitting the blue light with a peak wavelength of 460 nm are used. Specifically, as such an LED chip, there is a GaN LED chip in which for example an InGaN semiconductor is used in a light emitting layer. Note that, the emission wavelength characteristic and the type of the LED chip 703 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. In the present example, it is preferable that the peak wavelengths of the light emitted by the LED chips 703a, 703b, 703c, and 703d be in the wavelength range of 420 nm to 500 nm.
(Fluorescent Member)
As described above, the first fluorescent member 718 has the same configuration as the first fluorescent member 612a of the sixth example, and employs three type phosphors of the red phosphor, the green phosphor, and the yellow phosphor in a mixed manner. In addition, in a similar manner to the first fluorescent member 612a of the sixth example, red light, green light, and yellow light, which are generated by converting the wavelength of the blue light emitted by the LED chips 703a through the red phosphor, the green phosphor, and the yellow phosphor, and blue light of the LED chips 703a, which is transmitted through the first fluorescent member 718, are synthesized. Thereby, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor in the first fluorescent member 718 are determined such that the first-order light with the chromaticity of the chromaticity point WP1 in the XY chromaticity diagram of
Further, the second fluorescent member 719 has the same configuration as the second fluorescent member 612b of the sixth example, and employs two type phosphors of the green phosphor and the yellow phosphor in a mixed manner. In addition, in a similar manner to the second fluorescent member 612b of the sixth example, red light, green light, and yellow light, which are generated by converting the wavelength of the blue light emitted by the LED chips 703b through the green phosphor and the yellow phosphor, and blue light of the LED chips 703b, which is transmitted through the second fluorescent member 719, are synthesized. Thereby, the densities and the mixture ratio of the green phosphor and the yellow phosphor in the second fluorescent member 719 are determined such that the first-order light with the chromaticity of the chromaticity point WP2 in the XY chromaticity diagram of
Furthermore, the third fluorescent member 720 has the same configuration as the third fluorescent member 617 of the sixth example, and employs three type phosphors of the red phosphor, the green phosphor, and the yellow phosphor in a mixed manner. In addition, in a similar manner to the third fluorescent member 617 of the sixth example, red light, green light, and yellow light, which are generated by converting the wavelength of the blue light emitted by the LED chips 703c through the red phosphor, the green phosphor, and the yellow phosphor, and blue light of the LED chips 703c, which is transmitted through the third fluorescent member 720, are synthesized. Thereby, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor in the third fluorescent member 720 are determined such that the first-order light with the chromaticity of the chromaticity point WP3 in the XY chromaticity diagram of
In addition, the fourth fluorescent member 721 has the same configuration as the fourth fluorescent member 618 of the sixth example, and employs three type phosphors of the red phosphor, the green phosphor, and the yellow phosphor in a mixed manner. In addition, in a similar manner to the fourth fluorescent member 618 of the sixth example, red light, green light, and yellow light, which are generated by converting the wavelength of the blue light emitted by the LED chips 703d through the red phosphor, the green phosphor, and the yellow phosphor, and blue light of the LED chips 703d, which is transmitted through the fourth fluorescent member 721, are synthesized. Thereby, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor in the fourth fluorescent member 721 are determined such that the first-order light with the chromaticity of the chromaticity point WP4 in the XY chromaticity diagram of
Accordingly, the fourth light emitting unit U704 emits the first-order light with the chromaticity of the chromaticity point WP4 in the XY chromaticity diagram of
(Electric Circuit Configuration of Illumination Apparatus)
Since the light emitting section 701 is configured as described above, also in the illumination apparatus of the present example, in a similar manner to the illumination apparatus of the first and sixth examples, the synthetic light, which is generated by synthesizing the first-order light respectively emitted from the first to fourth light emitting units U701 to U704, is emitted as the illumination light of the illumination apparatus. Accordingly, by adjusting the intensity of the first-order light, which is emitted from each of the first to fourth light emitting units U701 to U704, in a similar manner to the illumination apparatus of the first and sixth examples, it is possible to emit white light with various color temperatures as the illumination light. Referring to
In the light emitting section 701, the LED chips 703a to 703d are mounted on the wiring board 702 as described above. Thereby, the LED chips 703a are connected to one another in parallel, the anode thereof is connected to the connection terminal 710a, and the cathode thereof is connected to the connection terminal 711a. Further, the LED chips 703b are connected to one another in parallel, the anode thereof is connected to the connection terminal 712a, and the cathode thereof is connected to the connection terminal 713a. Furthermore, the LED chips 703c are connected to one another in parallel, the anode thereof is connected to the connection terminal 714a, and the cathode thereof is connected to the connection terminal 715a. In addition, the LED chips 703d are connected to one another in parallel, the anode thereof is connected to the connection terminal 716a, and the cathode thereof is connected to the connection terminal 717a.
As shown in
In such an electric circuit configuration, by turning on the transistor Q721, forward currents supplied from the power supply 723 flow in the respective LED chips 703a, and thereby the LED chips 703a respectively emit light. Accordingly, by turning on the transistor Q721, the first light emitting unit U701, which is formed of the LED chips 703a and the first fluorescent member 718, emits the first-order light with the chromaticity of the chromaticity point WP1 in the XY chromaticity diagram of
Likewise, by turning on the transistor Q722, forward currents supplied from the power supply 723 flow in the respective LED chips 703b, and thereby the LED chips 703b respectively emit light. Accordingly, by turning on the transistor Q722, the second light emitting unit U702, which is formed of the LED chips 703b and the second fluorescent member 719, emits the first-order light with the chromaticity of the chromaticity point WP2 in the XY chromaticity diagram of
Further, by turning on the transistor Q723, forward currents supplied from the power supply 723 flow in the respective LED chips 703c, and thereby the LED chips 703c respectively emit light. Accordingly, by turning on the transistor Q723, the third light emitting unit U703, which is formed of the LED chips 703c and the third fluorescent member 720, emits the first-order light with the chromaticity of the chromaticity point WP3 in the XY chromaticity diagram of
Furthermore, by turning on the transistor Q724, forward currents supplied from the power supply 723 flow in the respective LED chips 703d, and thereby the LED chips 703d respectively emit light. Accordingly, by turning on the transistor Q724, the fourth light emitting unit U704, which is formed of the LED chips 703d and the fourth fluorescent member 721, emits the first-order light with the chromaticity of the chromaticity point WP4 in the XY chromaticity diagram of
In order to control on/off states of the transistors Q721 to Q724, the illumination apparatus of the present example is provided with an emission control section 724. All the transistors Q721 to Q724 are able to switch the on/off states in response to the respective base signals, and the emission control section 724 is configured to individually transmit the base signals to the respective bases. The emission control section 724 has practically the same configuration as the emission control section 513 of the fifth example, and thus performs the same emission control as the emission control section 513. Hence, the emission control section 724 has own memory (storage device) 724a used in storing information necessary for the emission control and the like.
Further, in a similar manner to the case of the fifth example, the illumination apparatus of the present example is also provided with an operation unit (operation member) 725 by which a user sets the total luminous flux or the color temperature of the illumination light, and a target value setting section 726 that sets the target correlation color temperature or the target total luminous flux in accordance with the operation performed on the operation unit 725. In the present example, the emission control section 724, the operation unit 725, and the target value setting section 726 constitute the control means of the present invention.
The emission control section 724 performs the emission control in the same manner as the case of the fifth example. Thereby, in the illumination apparatus of the present example, it is also possible to generate illumination light the same as that of the illumination apparatus of the fifth example. Accordingly, it is possible to change the color temperature of the illumination light emitted from the illumination apparatus in the range from the lower limit color temperature T1 to the upper limit color temperature T2. At this time, the chromaticity of the illumination light is approximate to the black-body radiation locus BL. As a result, it is possible to make the illumination light be white light which is natural without sense of discomfort.
Note that, in the present example, the electric circuit of the illumination apparatus is also not limited to the configuration shown in
In the electric circuit configuration of
(Modified Example of Light Emitting Section)
In the present example, instead of the LED chips emitting the blue light, it may also be possible to use the LED chips emitting the near-ultraviolet light. In this case, in order to generate the blue light, in addition to the red phosphor, the green phosphor, and the yellow phosphor used in the present example, the blue phosphor, which converts the wavelength of the near-ultraviolet light emitted by the LED chips so as to emit blue light, may be used. In this case, instead of the blue light respectively emitted through the first fluorescent member 718, the second fluorescent member 719, the third fluorescent member 720, and the fourth fluorescent member 721, the blue light emitted from the blue phosphor is used. Therefore, in view of this point, it is preferable to adjust the densities and the mixture ratio of the phosphors in the fluorescent members.
Further, in the case of using the LED chips emitting the near-ultraviolet light, as described in the sixth example, it is preferable to use a material, which has durability and transparency sufficient for the near-ultraviolet light emitted by the LED chips, in the fillers respectively used in the first to fourth fluorescent members 718 to 721. As specific examples of the filters, it may be possible to use the fillers described in the sixth example.
As described above, in the present example and modified example thereof, the light emitting unit group is formed of the light emitting sections each of which has four light emitting units integrally formed. Therefore, it becomes easier to treat the light emitting unit group, and it is possible to reduce the manufacturing costs and the number of manufacturing processes of the illumination apparatus.
In the fifth to seventh examples, the light emitting section, which is configured such that some or all the four light emitting units are integrated therein, is used in the illumination apparatus. However, the light emitting units may be individually formed, and used in the illumination apparatus. Therefore, one examples thereof will be hereinafter described as an eighth example.
(Configuration of Light Emitting Unit)
As the metallic substrate, it is preferable to use an aluminum substrate, a copper substrate, or the like which is excellent in a heat dissipation ability. However, among them, the aluminum substrate is more preferable in terms of costs, a lightweight property, and a heat dissipation ability. In addition, since the substrate main body 802a made of metal is used, the wiring pattern 804 and the wiring pattern 805 are formed on the surface of the wiring board 802, on which the LED chips 803 are mounted, with the electrical insulation layer 802b interposed between the substrate main body 802a and the patterns. Note that, the material of the substrate main body 802a is not limited to such a metallic substrate, and in a similar manner to the cases of the fifth to seventh examples, it may be possible to use the material with the electrical insulation property such as alumina ceramic which is excellent in electrical insulation and has a favorable heat dissipation ability.
The LED chip 803 has two electrodes for supplying the driving currents, one electrode (for example, the p electrode) is provided on the upper surface thereof, and the other electrode (for example, the n electrode) is provided on the lower surface. The electrode on the upper surface is connected to the wiring pattern 804 through the metal wire 806, and the electrode on the lower surface is directly connected to the wiring pattern 805 by using the eutectic solder 807. Note that, a method of mounting the LED chips 803 on the wiring board 802 is not limited to this, and an appropriate method may be selected in accordance with the position and the like of the electrodes provided in the LED chips 803. For example, it may be possible to employ double wire bonding which connects the two electrodes provided on the upper surface of each LED chip 803 to the corresponding wiring patterns of the wiring board 802 through the metal wire after the LED chips 803 are fixedly attached to predetermined positions of the wiring board 802. In addition, in a similar manner to the fifth to seventh examples, it may be possible to employ flip chip mounting which respectively connects the two electrodes positioned on the lower side of the LED chip 803 to the corresponding wiring patterns with the metal bump interposed therebetween.
As shown in
The basic configuration of the light emitting unit of the present example has been hitherto described, but in the present example, in a similar manner to the cases of the second and seventh examples, the light emitting unit group of the present invention is configured by using four types of light emitting units. In addition, the wavelength conversion characteristics of the fluorescent member 808 are different between the four types of light emitting units. Accordingly, hereinafter four types of light emitting units are respectively referred to as a first light emitting unit 801a, a second light emitting unit 801b, a third light emitting unit 801c, and a fourth light emitting unit 801d.
The fluorescent member 808, which is provided in the first light emitting unit 801a, is referred to as a first fluorescent member which holds a first phosphor in the filler 810 in a distributed manner. Likewise, the fluorescent member 808, which is provided in the second light emitting unit 801b, is referred to as a second fluorescent member which holds a second phosphor in the filler 810 in a distributed manner, and the fluorescent member 808, which is provided in the third light emitting unit 801c, is referred to as a third fluorescent member which holds a third phosphor in the filler 810 in a distributed manner. Furthermore, the fluorescent member 808, which is provided in the fourth light emitting unit 801d, is referred to as a fourth fluorescent member which holds a fourth phosphor in the filler 810 in a distributed manner. Note that, in the description below, light, which is emitted by each of the first to fourth light emitting units 801a to 801d, is referred to as first-order light, and light, which is generated by synthesizing the first-order light emitted by each of the first to fourth light emitting units 801a to 801d, is referred to as synthetic light.
(LED Chip)
In a similar manner to the illumination apparatuses of the fifth to seventh examples, the LED chips 803, the LED chips emitting the blue light with a peak wavelength of 460 nm are used. For example, there is a GaN LED chip in which for example an InGaN semiconductor is used in a light emitting layer. Note that, the emission wavelength characteristic and the type of the LED chip 803 is not limited to this, and it may be possible to employ the semiconductor light emitting elements such as various LED chips without departing from the technical scope of the present invention. In the present modified example, it is preferable that the peak wavelengths of the light emitted by the LED chips 803 be in the wavelength range of 420 nm to 500 nm.
(Fluorescent Member)
In a similar manner to the first wavelength conversion region P51 of the fluorescent member 505 of the fifth example, the first fluorescent member as the fluorescent member 808 of the first light emitting unit 801a is configured to emit the first-order light with the chromaticity of the chromaticity point WP1 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 803 of the first light emitting unit 801a is converted by the red phosphor, the green phosphor, and the yellow phosphor included in the first fluorescent member, and red light, green light, and yellow light are emitted. At this time, the blue light of the LED chip 803, which is transmitted through the first fluorescent member without wavelength conversion performed by the first fluorescent member, is emitted from the first fluorescent member together with the red light, the green light, and the yellow light. Accordingly, the first-order light, in which the red light, the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the first light emitting unit 801a.
In the first fluorescent member, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor of the filler 810 are determined on the basis of, as shown in
In a similar manner to the second wavelength conversion region P52 of the fluorescent member 505 of the fifth example, the second fluorescent member as the fluorescent member 808 of the second light emitting unit 801b is configured to emit the first-order light with the chromaticity of the chromaticity point WP2 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 803 of the second light emitting unit 801b is converted by the green phosphor and the yellow phosphor included in the second fluorescent member, and green light and yellow light are emitted. At this time, the blue light of the LED chip 803, which is transmitted through the second fluorescent member without wavelength conversion performed by the second fluorescent member, is emitted from the second fluorescent member together with the green light and the yellow light. Accordingly, the first-order light, in which the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the second light emitting unit 801b.
In the second fluorescent member, the densities and the mixture ratio of the green phosphor and the yellow phosphor of the filler 810 are determined on the basis of, as shown in
In a similar manner to the third wavelength conversion region P53 of the fluorescent member 505 of the fifth example, the third fluorescent member as the fluorescent member 808 of the third light emitting unit 801c is configured to emit the first-order light with the chromaticity of the chromaticity point WP3 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 803 of the third light emitting unit 801c is converted by the red phosphor, the green phosphor, and the yellow phosphor included in the third fluorescent member, and red light, green light, and yellow light are emitted. At this time, the blue light of the LED chip 803, which is transmitted through the third fluorescent member without wavelength conversion performed by the third fluorescent member, is emitted from the third fluorescent member together with the red light, the green light, and the yellow light. Accordingly, the first-order light, in which the red light, the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the third light emitting unit 801c.
In the third fluorescent member, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor of the filler 810 are determined on the basis of, as shown in
In a similar manner to the fourth wavelength conversion region P54 of the fluorescent member 505 of the fifth example, the fourth fluorescent member as the fluorescent member 808 of the fourth light emitting unit 801d is configured to emit the first-order light with the chromaticity of the chromaticity point WP4 in the XY chromaticity diagram of
The wavelength of a part of the blue light emitted by the LED chip 803 of the fourth light emitting unit 801d is converted by the red phosphor, the green phosphor, and the yellow phosphor included in the fourth fluorescent member, and red light, green light, and yellow light are emitted. At this time, the blue light of the LED chip 803, which is transmitted through the fourth fluorescent member without wavelength conversion performed by the fourth fluorescent member, is emitted from the fourth fluorescent member together with the red light, the green light, and the yellow light. Accordingly, the first-order light, in which the red light, the green light, the yellow light, and the blue light emitted in such a manner are synthesized, is emitted from the fourth light emitting unit 801d.
In the fourth fluorescent member, the densities and the mixture ratio of the red phosphor, the green phosphor, and the yellow phosphor of the filler 810 are determined on the basis of, as shown in
(Electric Circuit Configuration of Illumination Apparatus)
By adopting the above-mentioned configuration of the first to fourth light emitting units 801a to 801d, it is possible to make the electric circuit of the illumination apparatus of the present example have the same configuration as the electric circuit of the seventh example shown in
Accordingly, by adjusting the intensity of the first-order light, which is emitted from each of the first to fourth light emitting units 801a to 801d, in a similar manner to the seventh example, it is possible to emit white light with various color temperatures as the illumination light. Accordingly, by performing the same emission control as the fifth to seventh examples, it is possible to change the color temperature of the illumination light emitted from the illumination apparatus in the range from the lower limit color temperature T1 to the upper limit color temperature T2. At this time, the chromaticity of the illumination light is approximate to the black-body radiation locus BL. As a result, it is possible to make the illumination light be white light which is natural without sense of discomfort.
(Modified Example of Light Emitting Unit)
In the present example, instead of the LED chips emitting the blue light, it may be possible to use the LED chips emitting the near-ultraviolet light. In this case, in order to generate the blue light, in addition to the red phosphor, the green phosphor, and the yellow phosphor used in the present example, the blue phosphor, which converts the wavelength of the near-ultraviolet light emitted by the LED chips so as to emit blue light, may be used. In this case, instead of the blue light respectively emitted through the first fluorescent member, the second fluorescent member, the third fluorescent member, and the fourth fluorescent member, the blue light emitted from the blue phosphor is used. Therefore, in view of this point, it is preferable to adjust the densities and the content percentages of the phosphors in the fluorescent members.
Further, in the case of using the LED chips emitting the near-ultraviolet light, it is preferable to use a material, which has durability and transparency sufficient for the near-ultraviolet light emitted by the LED chips, in the filler 810. As the filler 810 in this case, it may be possible to use the filler of which a specific example is described in sixth example.
(Arrangement Example of Light Emitting Unit)
In addition, in the present example, the numbers of first to fourth light emitting units 801a to 801d can be arbitrarily determined on the basis of specification necessary for the illumination apparatus, characteristics of the light emitting units, or the like. For example, when using the plurality of first to fourth light emitting units 801a to 801d, it is preferable to evenly distribute the light emitting units with the same type in terms of favorable synthesis of the first-order light.
In the arrangement example of
In an eighth example, by adopting the basic configuration shown in
Specifically, the red phosphor used in the red cell 506r of the fifth example is used in the phosphor 809, and is held in the filler 810 in a distributed manner, thereby forming a red light emitting section, and the green phosphor used in the green cell 506g of the fifth example is used in the phosphor 809, and is held in the filler 810 in a distributed manner, thereby forming a green light emitting section. In addition, the yellow phosphor used in the yellow cell 506y of the fifth example is used in the phosphor 809, and is held in the filler 810 in a distributed manner, thereby forming a yellow light emitting section, and the diffusing particles used in the blue cell 506b of the fifth example is used instead of the phosphor 809, and is held in the filler 810 in a distributed manner, thereby forming a blue light emitting section.
The red light emitting section, the green light emitting section, the yellow light emitting section, and the blue light emitting section configured as described above are respectively disposed in the wavelength conversion regions of the first to fourth wavelength conversion regions P51 to P54 in place of the red cells 506r, the green cells 506g, the yellow cells 506y, and the blue cells 506b of the fifth example, on the basis of the numbers of cell regions thereof shown in the table of
Note that, in the modified example, by further changing the LED chips 803 used in the red light emitting section, the green light emitting section, and the yellow light emitting section, the LED chips, which emit red light, may be used in the red light emitting section, the LED chips, which emit green light, may be used in the green light emitting section, and the LED chips, which emit yellow light, may be used in the yellow light emitting section. In this case, as the phosphor 809, in a similar manner to the blue light emitting section, it is preferable to use diffusing particles, instead of the red phosphor, the green phosphor, and the yellow phosphor used in the red light emitting section, the green light emitting section, and the yellow light emitting section. Furthermore, each LED chip may emit light directly without using the diffusing particles.
Further, as the LED chips 803 respectively used in the red light emitting section, the green light emitting section, the yellow light emitting section, and the blue light emitting section, the LED chips emitting the near-ultraviolet light may be used instead of the LED chips emitting the blue light. In this case, in the blue light emitting section, instead of the diffusing particles, it is preferable to use the blue phosphor as the phosphor 809.
The illumination apparatus according to the embodiment of the present invention has hitherto been described, but the present invention is not limited to the above-mentioned examples and modified examples. For example, in each example and each modified example, the first-order light, which is emitted from each light emitting unit, is generated by using the four types of light of the red light, the green light, the yellow light, and the blue light, but the type of the light used in synthesis of the first-order light emitted from each light emitting unit is not limited to this, and various types of light may be used without departing from the technical scope of the present invention. Further, such a configuration for emitting light is not limited to the LED chips or the combination of the LED chips and the fluorescent member of the above-mentioned examples and modified examples. For example, it is also possible to obtain the same emission colors by using organic EL elements or the like.
Further, the electric circuit configuration of the illumination apparatus of each of the examples and modified examples is just an example, and may be modified into various forms without departing from the technical scope of the present invention. For example, instead of connecting the LED chips in parallel, they may be connected in series, and the serial connection and the parallel connection may be used in combination. Further, in place of the current-limiting resistor, a low current circuit may be used. Furthermore, at the time of on/off control of the transistors to control the current supply, the currents flowing in the transistors may also be controlled. In this case, the current-limiting resistor is also not necessary.
Although the present invention has been described in detail with reference to specific embodiments, it will be readily apparent to those skilled in the art that various modifications and alterations can be applied to the embodiments without departing from the technical scope and spirit of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-202493 | Sep 2010 | JP | national |
| 2011-051854 | Mar 2011 | JP | national |
| 2011-186451 | Aug 2011 | JP | national |
This application is a continuation of PCT application No. PCT/JP2011/070523, which was filed on Sep. 8, 2011 based on Japanese Patent Application (No. 2010-202493) filed on Sep. 9, 2010, Japanese Patent Application (No. 2011-051854) filed on Mar. 9, 2011, and Japanese Patent Application (No. 2011-186451) filed on Aug. 29, 2011, the contents of which are incorporated herein by reference. Also, all the references cited herein are incorporated as a whole.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2011/070523 | Sep 2011 | US |
| Child | 13753920 | US |
