Patent Application
20230411567
The disclosure relates to a lighting technical field, in particular to a light emitting device.
With applications of intelligent lamps to home lighting. People not only require dimming the luminance, but also pursue dimming the color temperature of the white light and tuning ambient light which is also called tuning the color chromaticity.
Since a good chromaticity tunable function means a wide color gamut which requires the R\G\B light beam participating in the light adjustment has a narrower FWHM (Full Width Half Maximum) and suitable luminance. But for the dimming of the color temperature, it is hoped that at least two white lights with different color temperatures participating in color temperature dimming will have a better continuous spectrum which required that the FWHM of each light beam mixed into the white light should not be too narrow. Therefore, in order to realize the above tuning and dimming function, the existing lamps usually use at least five different components to independently complete the color tuning and dimming.
This disclosure provides a different solution, it provides a light emitting device, which can dim the color temperature and tune ambient light only by four different light emitting units.
In one aspect, an embodiment of the disclosure provides a light emitting device which includes a red light emitting unit, a green light emitting unit, a blue light emitting unit, and a white light emitting unit. The red light emitting unit includes a first blue light emitting chip and a red fluorescent material, and a dominant wavelength of a light emitted by the red light emitting unit is in a range of 610 nanometers (nm) to 635 nm.
In another aspect, another embodiment of the disclosure provides a light emitting device including a red light emitting unit, a green light emitting unit, and a blue light emitting unit. The green light emitting unit includes a third blue light emitting chip and a narrow-wavelength green fluorescent material, and a dominant wavelength of a light emitted by the green light emitting unit is in a range of 535 nm to 550 nm.
In a still another aspect, a still another embodiment of the disclosure provides a light emitting device including a red light emitting unit, a green light emitting unit, and a blue light emitting unit. The red light emitting unit includes a first blue light emitting chip and a red fluorescent material, and a dominant wavelength of a light emitted by the red light emitting unit is in a range of 610 nm to 635 nm.
The above technical solution can have one or more of the following advantages or beneficial effects: the light emitting device is designed with a structure including a red light emitting unit, a blue light emitting unit, a green light emitting unit and a white light emitting unit; by designing the structure of the red light emitting unit, the light emitting device can tune ambient light and dim color temperature by the four light emitting units to reduce cost. In addition, on the basis of the disclosure, an ambient light adjusting device with low cost and high brightness can be realized by removing the white light emitting unit.
In order to more clearly explain the technical solution of the disclosure, the following will briefly describe attached drawings needed in the description of the embodiments. Apparently, the attached drawings in the following description are only some of the embodiments of the disclosure. For those skilled in the art, other drawings can be obtained from these attached drawings without paying creative works.
The following will clearly and completely describe technical solutions in the embodiments of the disclosure with reference to the attached drawings in the embodiments of the disclosure. Apparently, the described embodiments are only some of the embodiments of the disclosure, not all of them. Based on the embodiments of the disclosure, all other embodiments obtained by those skilled in the art without creative works should belong to the scope of protection of the disclosure.
As shown in
Specifically, the green light emitting unit 13 emits a green light. Furthermore, the green light emitting unit 13 includes at least one green chip (not shown in attached drawings), and a dominant wavelength of the green chip is in a range of 515 nm to 535 nm.
According to the latest research progress, it is found that the green light emitting unit 13 can further include at least one third blue light emitting chip and a narrow-wavelength green phosphor, where the narrow-wavelength green phosphor is a phosphor with a FWHM less than 70 nm and emitting a green light after being excited. By selecting the third blue light emitting chip and the green phosphor, a dominant wavelength of a light emitted by the green light emitting unit is in a range of 535 nm to 550 nm. The specific selection will be detailed in other embodiments hereinafter.
The blue light emitting unit 12 emits a blue light. Specifically, the blue light emitting unit 12 includes at least one blue chip (not shown in attached drawings), and a dominant wavelength of the blue chip is in a range of 460 nm to 475 nm. According to the latest research progress, it is found that the blue chip with the dominant wavelength between 455 nm and 460 nm, for example, the blue chip with the dominant wavelength of 475.5 nm, can also be used in the blue light emitting unit 12. That is to say, the blue light emitting unit can include at least one blue chip, and the dominant wavelength of the at least one blue chip can be in a range of 455 nm to 475 nm.
The red light emitting unit 11 includes a first blue light emitting chip and a red fluorescent material. Here, the red fluorescent material is a fluorescent material that emits a red light after being excited. Specifically, a dominant wavelength of the first blue chip is in a range of 445 nm to 460 nm. The red fluorescent material includes a first red phosphor and a second red phosphor. Specifically, the first red phosphor is a KSF (i.e., K2SiF6:Mn4+, a tetravalent manganese fluoride) phosphor. It should be noted that the KSF phosphor itself is yellow, but it will emit a red light after being excited by a blue light, so that it is also called red phosphor. The second red phosphor is a long-wavelength nitride red phosphor. In the disclosure, the long-wavelength nitride red phosphor mainly refers to a nitride red phosphor whose peak wavelength is greater than that of the first red phosphor. In an embodiment, the long-wavelength nitride red phosphor is a nitride red phosphor which has a peak wavelength in a range of 635 nm to 660 nm. The nitride red phosphor is generally called CASN or 1113 phosphor, and a basic composition of the nitride red phosphor is CaAlSiN3:Eu. According to the latest research progress, it is found that the second red phosphor is not limited to long-wavelength nitride red phosphor, and it can be a certain amount of short-wavelength nitride red phosphor(that is, nitride red phosphor with a peak wavelength less than that of the first red phosphor, preferably a nitride red phosphor with a peak wavelength less than 635 nm) combined with long-wavelength nitride red phosphor. Therefore, according to the latest research progress, it can be better described that the nitride red phosphor is selected as the second red phosphor. Specifically, a FWHM of the KSF phosphor is very narrow and less than 30 nm in common, and has a peak. Therefore, the luminance of the KSF phosphor is high, which is conducive to tuning the ambient light. Compared with the KSF phosphor, the second red phosphor has a higher wavelength band and a wider FWHM. When spectral overlap occurs, it can be understood that an overlapped spectrum is more continuous if the FWHW is wider, and thus a light of the overlapped spectrum is closer to a natural light and has a higher color rendering index, which is conducive to dimming the color temperature. Therefore, the light emitting device 10 including the above-mentioned red light emitting unit 11, blue light emitting unit 12, green light emitting unit 13 and white light emitting unit 14 can realize the tuning of ambient light and dimming of the color temperature.
According to the latest research progress, it is found that the first red phosphor can be not only KSF phosphor, but also KGF (i.e., K2GeF6:Mn4+) phosphor and KTF (i.e., K2TiF6:Mn4+) phosphor. The KSF phosphor, the KGF phosphor and the KTF phosphor are all fluorosilicate materials excited by tetravalent manganese, which can be collectively called a fluoride red phosphor, and a FWHM thereof is usually less than 30 nm.
The white light emitting unit 14 includes a second blue light emitting chip with a dominant wavelength being in a range of 445 nm to 460 nm and a multicolor fluorescent material. It can be understood that the multicolor fluorescent material can convert a blue light emitted by the second blue light emitting chip into lights of other colors, and thus the lights of other colors can be mixed with the blue light of the second blue light emitting chip not absorbed by the multicolor fluorescent material to form a white light. Specifically, the multicolor fluorescent material includes a third red phosphor. Specifically, the third red phosphor is a short-wavelength red phosphor (in the disclosure, the short-wavelength red phosphor is a short-wavelength red phosphor with a peak wavelength less than 635 nm), and thus a part of the blue light emitted by the second blue light emitting chip passes through the third red phosphor to emit a red light. In addition, the multicolor fluorescent material further includes at least one of a green phosphor and a yellow-green phosphor. For example, the green phosphor such as Lu3Al5O12:Ce (LuAG) and Y3(Ga,Al)5O12:Ce (GaYAG); the yellow-green phosphor such as SiAlON:Eu (β-sialon), and the disclosure is not limited to these. In an embodiment, the third red phosphor used in the white light emitting unit 14 of the disclosure is a nitride red phosphor having a peak wavelength of an emission (i.e., a red light emitted by the third red phosphor) in a range of 605 nm-620 nm, the nitride red phosphor is generally called CASN or 1113 phosphor, a basic composition of the nitride red phosphor is CaAlSiN3:Eu. The nitride red phosphor can be added strontium (Sr) element to form (Sr,Ca)AlSiN3:Eu according to a selection of a wavelength, thereby to make the peak wavelength of the nitride red phosphor move to a direction of short waves. The (Sr,Ca)AlSiN3:Eu can also be called CASN or 1113 phosphor for short, and a basic composition of the (Sr,Ca)AlSiN3:Eu is CaAlSiN3:Eu, and different peak wavelengths represents different contents of the strontium element in the (Sr,Ca)AlSiN3:Eu. In an embodiment, a color temperature of the white light emitting unit 14 is in a range of 1800 Kelvin (K) to 3000K, the following embodiments only exemplified at 3000 K, it should be understood that the color temperature of the white light emitting unit 14 can be any other value. The white light emitting unit 14 includes one or more the second blue light emitting chip with a dominant wavelength being in a range of 445 nm to 460 nm.
It can be understood that the structure of the light emitting device 10 shown in
Specifically, as shown in
As shown in
An embodiment of the disclosure provides a light emitting device 10 which has an excellent color tuning effect of an ambient lamp. It should be noted that the higher the color richness of an ambient light, the better the color tuning effect of the ambient lamp, and the color richness of the ambient light can be evaluated by a national television standards committee (NTSC) color gamut. As shown in
Specifically, TABLE 1 shows parameters of the light emitting device 10 provided by an embodiment of the disclosure, the light emitting device 10 realizes the dimming of color temperature and the tuning of ambient light by adjusting an electric current ratio of the four light emitting units:
In the TABLE 1, “30 C” means a color temperature of the white light emitting unit 14 being 3000K. A dimming range of the color temperature of the light emitting device 10 is in a range of 2700K to 6500K. In the dimming range of the light emitting device 10, color rendering indexes of the light emitting device 10 are 90 on average. It should be noted that the color temperature of the light emitting device 10 provided by an embodiment of the disclosure can be adjusted to be lower than 2700K or higher than 6500K, and the color temperature of the white light emitting unit 14 can be 2000K or any other color temperature value. The “x” (also referred to CIEx) and “y” (also referred to CIEy) in the TABLE 1 are chromaticity coordinate values corresponding to a color temperature in a chromaticity diagram (also referred to CIE diagram).
Specifically, when the color temperature is adjusted, there are at least three light emitting units emit lights at the same time. In addition, it can be seen in TABLE 1 that the light emitting device 10 can achieve different color temperatures by adjusting electric currents of the four light emitting units. Most of color rendering indexes (CRI) of the light emitting device 10 provided by the embodiment of the disclosure are greater than 90, i.e., the light emitting device has high color rendering indexes. The higher the color rendering indexes, the easier it is for the human eye to distinguish different colors of objects. Under the light source with poor color rendering property for a long time, the sensitivity of human eye cone cells will be reduced, which is easy to cause eye fatigue. The color rendering indexes of the embodiment of the disclosure are high, which provides a good user experience.
In an embodiment, as shown in
It should be noted that the selection of electric currents will change according to sizes of chips. The parameters in TABLE 1 are only for specific adjustments and controls of the chips used in specific embodiments to verify that the light emitting device 10 of the disclosure can achieve the effect of adjusting the ambient light and the color temperature and high color rendering indexes only by four light emitting units, and the electric current ratio of the light emitting device 10 is not intended to limit the technical scope of the disclosure. In a more general and applicable way, the regulation of each of the light emitting units of the light emitting device 10 of the disclosure is shown by luminance ratios of the light emitting units. The luminance 100 lm of the white light unit 14 is taken as a reference, TABLE 2 shows parameters of the light emitting device 10 provided by an embodiment of the disclosure, which realizes the dimming of color temperature and the tuning of ambient light by adjusting the luminance ratios of the four light emitting units:
In the TABLE 2, “30 C” means a color temperature of the white light emitting unit 14 being 3000K. “lm” is a physical unit called lumen which is used to describe the luminous flux, and the lumen represents a total amount of visible light emitted by a light source in a unit time. When the color temperature of the light emitting device 10 is 2700K, at the same time, a luminous flux of a red light emitted by the red light emitting unit 11 is 10.7 lumens, a luminous flux of a green light emitted by the green light emitting unit 13 is 8.9 lumens, a luminous flux of a blue light emitted by the blue light emitting unit 12 is 0 lumens, and a luminous flux of a white light emitted by the white light emitting unit 14 is 100 lumens. It should be noted that each specific value in the TABLE 2 have a tolerance (i.e., changing range) of ±50%. Although TABLE 2 only shows that the color temperature of the light emitting device 10 changes from 2700K to 6500K, the color temperature of the light emitting device 10 provided by other embodiments of the disclosure can be adjusted to be lower than 2700K or higher than 6500K, and the color temperature of the white light emitting unit can be 2000K or any other color temperature value.
Therefore, the luminance of a red light emitted by the red light emitting unit 11 in the light emitting device 10 participating in mixing light decreases with the increase of color temperature. The luminance of a green light emitted by the green light emitting unit 13 participating in mixing light in the light emitting device 10 increases with the increase of the color temperature. The brightness of a blue light emitted by the blue light emitting unit 12 participating in the mixing light in the light emitting device 10 increases with the increase of the color temperature. It should be noted that “30 C” refers to a color temperature of the white light emitting unit 14 is 3000K. It can be understood that although TABLE 1 and TABLE 2 only show that the color temperature of the light emitting device 10 changes from 2700K to 6500K, the color temperature of the light emitting device 10 provided by other embodiments of the disclosure can be adjusted to be lower than 2700K or higher than 6500K, and the color temperature of the white light emitting unit 14 can be 2000K or any other color temperature value.
As shown in
In an embodiment of the disclosure, the red light emitting unit 11 uses the technical solution of combining a blue light emitting chip with multiple red phosphors to emit a specific red light, the technical solution can not only replace a traditional red chip to participate in the adjustment of color lights, but also participate in the adjustment of the color temperature of a white light. More importantly, it can make a color rendering index of a final light reach about 90 without requiring that all the color lights participating in the adjustment of the color temperature have high color rendering indexes. Specifically, by adjusting a mass ratio between the first red phosphor and the second red phosphor, the red light emitting unit 11 can emit a red light with a dominant wavelength in a range of 615 nm to 635 nm. According to the latest research progress, it is found that by adjusting the mass ratio of the first red phosphor to the second red phosphor, the red light emitting unit 11 can emit a red light with the dominant wavelength in a range of 610 nm to 615 nm, which is also suitable for the light emitting device of the disclosure. Under the excitation of a blue light emitted by the first blue light emitting chip, the KSF phosphor converts a part of the blue light into a narrow-wavelength red light with a peak wavelength in a range of 630 nm to 634 nm, and the long-wavelength nitride red phosphor also converts a part of the blue light into a wide-wavelength red light with a peak wavelength in a range of 635 nm to 660 nm. Among them, the KSF phosphor has a narrow FWHM (FWHM is considered to be narrow if it is less than 30 nm), and thus the spectrum of the red light emitting unit 11 has a narrow peak. Since the color purity of the red light excited by the KSF phosphor is high, it is easy to adjust the light. The nitride red phosphor has good absorption characteristics to the blue light, and thus the long-wavelength nitride red phosphor can continue to convert and absorb the blue light emitted by the first blue light emitting chip while not absorbed by the KSF phosphor, thus reducing the impact of the blue light emitted by the first blue light emitting chip on the color purity of the red light emitted by the red light emitting unit 11. According to the latest research progress, it is found that the KSF red phosphor can be replaced by a nitride red phosphor such as KGF and KTF, and a short-wavelength nitride phosphor can be used together with long-wavelength nitride red phosphor to reduce the absorption of a narrow-wavelength red light by the long-wavelength nitride phosphor and improve the brightness of the whole red light emitting unit 11.
As shown in
Since the red phosphors are used in the red light emitting unit 11 and the white light emitting unit 14 to emit red lights. Therefore, in order to avoid the mutual interference of the red lights of the red light emitting unit 11 and the white light emitting unit 14 affecting the tuning of ambient light and the dimming of color temperature of the light emitting device 10, the color rendering index of the white light emitting unit 14 does not need to be too high. If the color rendering index of the white light emitting unit 14 is high, the spectrum of the red light emitted by the third red phosphor in the white light emitting unit 14 may excessively overlap with the spectrum of the red light emitted by the red light emitting unit 11, which makes the overlapped spectrum fail to meet the requirements of tuning ambient light and dimming color temperature. Therefore, it is recommended that the color rendering index of the white light emitting unit 14 is less than or equal to 80. The FWHM of the white light emitted by the white light emitting unit 14 is less than or equal to 110 nm. Specifically, in an embodiment, the color rendering index of the white light emitting unit 14 is suggested to be about 70. Therefore, it can be understood that although the color rendering index of the white light emitting unit 14 is low, the color rendering index of the light emitting device 10 can also be high.
In an embodiment of the disclosure, the light emitting device 10 is designed with a structure including the red light emitting unit 11, the blue light emitting unit 12, the green light emitting unit 13 and the white light emitting unit 14, and the red light emitting unit 11 includes the KSF phosphor with a very narrow FWHM and a peak, the long-wavelength nitride red phosphor which can absorb the blue light, and the first blue light emitting chip. Therefore, the tuning of ambient light and dimming of color temperature can be realized by the four light emitting units, which reduces the cost. In addition, the light emitting device 10 provided by the embodiment further has a beneficial effect that although the color rendering index of the white light emitting unit 14 is low, the color rendering index of the light emitting device 10 is high.
It is particularly important to mention that although the above embodiments of the disclosure are introduced with a light emitting device including four different light emitting units. However, those skilled in the art can remove the white light emitting unit on the basis of the disclosure, as such, an ambient light adjusting device with low cost and high brightness can be realized. The following embodiments, according to the latest research progress, introduce some research progress of the red light emitting unit and the green light emitting unit, taking the ambient light adjusting device including red light emitting unit, the blue light emitting unit, and the green light emitting unit as an example.
Referring to
Specifically, the blue light emitting unit 12 emits a blue light. Furthermore, the blue light emitting unit 12 includes at least one blue chip (not shown in the attached drawings), and a dominate wavelength of the blue chip is in a range of 455 nm to 475 nm.
In a specific implementation of this embodiment, the green light emitting unit 12 may include, for example, a third blue light emitting chip and a narrow-wavelength green phosphor. Referring to
In the related art, a green light emitting chip is usually selected to be the green light emitting unit. A wavelength of a commonly used green light emitting chip is in a range of 515 nm to 530 nm, chromaticity coordinate values x and y corresponding to the dominate wavelength of 520 nm are about 0.14 and 0.705, respectively, chromaticity coordinate values x and y corresponding to the dominate wavelength of 523 nm are about 0.15 and 0.727, respectively, and chromaticity coordinate values x and y corresponding to the dominate wavelength of 515 nm to 530 nm are about 0.12 to 0.17, and 0.68 to 0.75, respectively. A color purity of a green light emitted by the commonly used green light emitting chip is about 74%. In order to ensure the color consistency of the green light, it is usually necessary to choose a green chip with a wavelength of 5 nm, which will lead to higher cost.
In this embodiment, the green light emitting unit 12 is set to include the third blue light emitting chip and the narrow-wavelength green phosphor, Due to the selection of the green phosphor, the dominate wavelength of the emitted light is in a range of 535 nm to 550 nm, x is in a range of 0.25 to 0.3, and y is in a range of 0.6 to 0.63. Compared with the solution using the green light emitting chip, a corresponding NTSC color gamut is decreased, and it is about 86%. However, from the perspective of color tuning of the RGB ambient light, sacrificing a certain NTSC color gamut can improve the color consistency of green light and reduce the cost of chip selection, and the color gamut value is still 86%, which is still a very market choice.
It is worth mentioning that the way that the green light emitting unit 12 is arranged to include the third blue light emitting chip and the narrow-wavelength green phosphor is not only suitable for a RGB light emitting device, but also suitable for RGBW light emitting device as shown in
In the RGBW light emitting device, the green light emitting unit 12 is arranged to include the third blue light emitting chip and the narrow-wavelength green phosphor. In an illustrated embodiment, a color temperature of the white light emitting unit 14 is 2500K; the color rendering index CRI is less than 80, for example, the color rendering index CRI is about 70; the FWHM is less than 110 nm; the peak wavelength is about 600 nm; and a color point center CIExy is (0.487, 0.432). Referring to
In a specific implementation of this embodiment, the red light emitting unit 11 may, for example, include a first blue light emitting chip and a red phosphor, and the dominate wavelength of the light emitted by the red light emitting unit 11 may, for example, be in a range of 610 nm to 635 nm. With this arrangement, the brightness of the light emitted by the red light emitting unit 11 can be improved, and the purity of the light emitted by the red light emitting unit 11 is greater than or equal to 0.96. It is worth mentioning that the red light emitting unit 11 in this embodiment is suitable not only for the RGB light emitting device, but also for the RGBW light emitting device as shown in
Specifically, referring to
The use of the long-wavelength nitride red phosphor is to shift the dominate wavelength of the red light emitting unit to a long-wavelength direction compared with the peak wavelength of the fluoride phosphor, so that the dominate wavelength of the red light emitting unit can meet the requirements of high color gamut. However, the long-wavelength nitride red phosphor will also absorb the light converted from the fluoride red phosphor to a certain extent, resulting in a decrease in brightness. The greater the amount of usage of the long-wavelength nitride red phosphor, the more obvious the decrease in brightness. If the amount of nitride red phosphor is insufficient, it will not be enough to absorb the excess blue light not absorbed by the fluoride red phosphor in the first blue light emitting chip, and the purity of the light emitted by the red light emitting unit 11 cannot be guaranteed. Therefore, when the dominate wavelength of the light emitted by the red light emitting unit 11 is in a range of 610 nm to 625 nm, a certain amount of the short-wavelength nitride red phosphor can be used in combination with the long-wavelength nitride red phosphor, and a wavelength difference between the long-wavelength nitride red phosphor and the short-wavelength nitride red phosphor can be for example greater than 10 nm. Because two kinds of nitride red phosphors with different peak wavelengths are used, the red light spectrum will be relatively symmetrical. By adjusting a ratio of long-wavelength nitride red phosphor to the short-wavelength nitride red phosphor, a ratio of an intensity of the red light spectrum emitted by the red light emitting unit 11 in a wavelength of 700 nm to an intensity of the red light spectrum emitted by the red light emitting unit 11 in a wavelength of 600 nm is less than or equal to 110%. TABLE 3 shows relevant parameters corresponding to implementations with different proportions of long-wavelength nitride red phosphor and short-wavelength nitride red phosphor. It can be clearly seen that the brightness of the light emitted by the red light emitting unit 11 can be improved and the purity of the light emitted by the red light emitting unit 11 is greater than or equal to 0.96.
Referring to
In order to improve the luminous brightness of the red light emitting unit 11, it can be made by, for example, a layered dispensing process. Specifically, referring to
In particular, for the red light emitting unit 11 whose dominate wavelength is required to be in a range of 625 nm and 635 nm, a mass ratio of the first red phosphor to the second red phosphor is different in the upper region V1 from that in the peripheral region V2 in order to reduce the absorption of the nitride red phosphor to the light emitted by fluoride red phosphor and further improve the brightness. Based on the uniformity of each layer of fluorescent glue in the dispensing process, it can be approximately considered that the volume ratio or cross-sectional thickness (average thickness or median thickness) ratio of the first red fluorescent adhesive layer 112 a or 112b and the second red fluorescent adhesive layer 113 a or 113b is different in the upper region V1 from that in the peripheral region V2. Based on the control of the concentration of the dispensing process, the above characteristics are usually intuitively reflected in that the thickness (average thickness or median thickness) of the first red fluorescent adhesive layer is greater than that of the second red fluorescent adhesive layer in the upper region V1 or the peripheral region V2. For example, referring to
Referring to
Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the disclosure, not to limit it; Although the disclosure has been described in detail with reference to the preceding embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the preceding embodiments, or equivalent replace some of the technical features. These modifications or substitutions do not make the essence of the corresponding technical solutions separate from the spirit and scope of the technical solutions in the embodiments of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022106762535 | Jun 2022 | CN | national |
| 2023106985097 | Jun 2023 | CN | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 18299848 | Apr 2023 | US |
| Child | 18356314 | US |
