Patent Grant
9730290
Field
The present invention relates to a dimmable alternating current (AC) driven light emitting diode (LED) illuminating apparatus, and more particularly, to an AC driven light emitting diode (LED) illuminating apparatus capable of displaying an appropriate dimming level over an entire section of the dimming level using a TRIAC dimmer configured to perform is dimming control via phase control.
Discussion of the Background
Generally, a diode device for light emission such as a light emitting diode (LED) has been driven only by direct current (DC) power due to diode characteristics. Therefore, a light emitting apparatus using an LED according to the related art has been restrictively used, and should include a separate circuit such as a switching mode power supply (SMPS) in order to be driven by alternating current (AC) power of 220V that is currently used at home. Therefore, a circuit of the light emitting apparatus has become complicated, and a cost required for manufacturing the light emitting apparatus has increased.
In order to solve these problems, research into an LED that may be driven even by AC power by connecting a plurality of light emitting cells in series with or parallel with each other has been actively conducted.
In order to solve the problems in the related art as described above, a sequential driving scheme of LEDs using AC power has been suggested. According to the sequential driving scheme, when an illuminating apparatus including three LED groups is assumed, in a situation in which an input voltage is increased over time, a first LED group first starts to emit light at Vf1, a second LED group connected in series with the first LED group starts to emit light at Vf2 higher than Vf1, and a third LED group connected in series with the second LED group and the first LED group starts to emit light at Vf3 higher than Vf2. In addition, in a situation in which the input voltage is decreased over time, the third LED group stops emitting the light at Vf3, the second LED group stops emitting the light at Vf2, and the first LED group finally stops emitting the light at Vf1, such that an LED driving current is designed so as to be approximate to the input voltage.
Meanwhile, a dimming control of the LED indicates that a luminescent flux or an illumination (Lux) of an LED illuminating apparatus, that is, generally, a brightness of a light source is changed depending on an applied supplying voltage, and a dimmable light source means an apparatus performing the above-mentioned illumination control function in the illuminating apparatus. This LED dimmable system is included in the LED illuminating apparatus in order to decrease power consumption of the LED illuminating apparatus and efficiently operate the LED illuminating apparatus. Particularly, heat generated due to a continuous light emitting operation of the LED is a factor of decreasing quality and efficiency of an illuminating operation. Therefore, in order to reflect a demand by a user and decrease power consumption, a dimming function has been generally added to the LED illuminating apparatus. Among the LED illuminating apparatuses to which the dimming function is added, the LED illuminating apparatus using the DC power as described above is driven by converting the AC power into the DC power using the SMPS. Therefore, dimming is relatively easy, such that dimming control characteristics may be expected to some degree.
However, in the case of the AC driven LED illuminating apparatus as described above, the LED is driven only by a voltage generated by rectifying the AC power, such that it is not easy to implement a dimming function and it is difficult to secure linearity in a dimming control. Particularly, in the case of an AC driven LED illuminating apparatus using the sequential driving scheme, since a driving voltage fluctuates due to a phenomenon that a power supply voltage temporally descends or ascends simultaneously with turning on/off the LEDs at the next step due to internal impedances of an AC power supplying line and a dimmer at a point in time in which the number of LED groups light-emitted depending on a magnitude of the driving voltage is changed (for example, a change point in time from 1-stage driving to 2-stage is driving, a change point in time from 2-stage driving to 3-stage driving, or the like), that is, a change point in time in which the driving voltage divided into two stages or more is exceeded, such that an unstable phenomenon may occur. That is, in the case of the AC driven LED illuminating apparatus having the dimming function according to the related art, ideal illumination change characteristics do not appear over an entire section of a dimming level, and a phenomenon that a luminescent flux is irregularly changed in a portion of a dimming control section occurs.
The present invention is to solve the problems in the related art as described above.
An object of the present invention is to provide an alternating current (AC) driven light emitting diode (LED) illuminating apparatus capable of having improved dimming characteristics over an entire section of a dimming level.
Another object of the present invention is to provide an AC driven LED illuminating apparatus capable of displaying very excellent dimming characteristics by interworking with a TRIAC dimmer configured to perform a dimming control using a phase control.
Still another object of the present invention is to provide an AC driven LED illuminating apparatus capable of overcoming a fluctuation phenomenon that LED groups are repeatedly turned on and turned off at the time of being sequentially driven.
Yet still another object of the present invention is to provide an AC driven LED is illuminating apparatus capable of more efficiently performing a dimming control by changing an LED driving current associated with a driving voltage phase-controlled depending on a dimming level.
Yet still another object of the present invention is to provide an AC driven LED illuminating apparatus capable of removing a phenomenon that a brightness irregularly fluctuates even though a first dimming level of a dimmer is excessively low due to a limitation function of maintaining an LED driving current for 1-stage driving as a predetermined value even at a minimum dimming level.
Characteristic configurations of the present invention for accomplishing the objects of the present invention as described above and unique effects of the present invention to be described will be described below.
According to an exemplary embodiment of the present invention, there is provided a dimmable AC driven LED illuminating apparatus including: a dimmer receiving AC power and controlling the received AC power depending on a selected dimming level to generate and output the controlled AC power; a rectifying unit receiving the controlled AC power output from the dimmer and full-wave rectifying the controlled AC power to generate and output a driving voltage; a dimming level detecting unit receiving the driving voltage to detect the selected dimming level and outputting the detected dimming level signal; first to n-th LED groups (n indicates a positive integer equal to or larger than 2) receiving the driving voltage to be sequentially driven depending on a control of an LED driving module and including one or more LEDs, respectively; and the LED driving module judging a voltage level of the driving voltage, controlling the sequential driving of the first to n-th LED groups depending on the judged voltage level of the driving voltage, and performing a constant current control on an LED driving is current based on the dimming level signal.
The LED driving module may determine a reference value of the LED driving current in proportion to a magnitude of the dimming level signal and control a maximum value of the LED driving current based on the determined reference value.
The LED driving module may control magnitudes of the LED driving current to be different from each other in each driving section.
The LED driving module may control the LED driving current to be sequentially increased from a first LED driving current for a first stage driving section to an n-th LED driving current for an n-th stage driving section.
The dimmer may be a TRIAC dimmer.
The dimmable AC driven LED illuminating apparatus may further include a trigger current maintaining circuit connected between the TRIAC dimmer and the rectifying unit to allow a TRIAC trigger current to flow to an AC power input or a rectified voltage output or act as a dummy load.
The trigger current maintaining circuit may be a bleeder circuit.
The dimmable AC driven LED illuminating apparatus may further include an electromagnetic interference (EMI) filter connected between the dimmer and the rectifying unit and attenuating high frequency noise of the phase-controlled AC power.
The dimmable AC driven LED illuminating apparatus may further include a surge protecting unit connected to an output terminal of the rectifying unit and protecting a circuit.
The dimming level detecting unit may average the driving voltage to detect the dimming level.
The dimming level detecting unit may include an RC integration circuit.
The dimming level detecting unit may further include a voltage limiting circuit limiting the driving voltage to a maximum voltage or less.
The dimming level detecting unit may be embedded as an rms converter in the LED driving module to convert the driving voltage into a direct current (DC) signal.
The LED driving module may selectively enable and disable a dimming control function.
The LED driving module may include an automatic sensing circuit sensing whether or not a dimming circuit is connected to automatically select whether the dimming control function is enabled or disabled.
The dimmable AC driven LED illuminating apparatus may further include a driving voltage stabilizing unit decreasing and stabilizing the driving voltage supplied to the LED driving module.
Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. These exemplary embodiments will be described in detail for those skilled in the art in order to practice the present invention. It should be appreciated that various exemplary embodiments of the present invention are different from each other, but do not have to be exclusive. For example, specific shapes, structures, and characteristics described in the present specification may be implemented in another exemplary embodiment without departing from the spirit and the scope of the present invention in is connection with an exemplary embodiment. In addition, it should be understood that a position and an arrangement of individual components in each disclosed exemplary embodiment may be changed without departing from the spirit and the scope of the present invention. Therefore, a detailed description to be described below should not be construed as being restrictive. In addition, the scope of the present invention is defined only by the accompanying claims and their equivalents if appropriate. Similar reference numerals will be used to describe the same or similar functions throughout the accompanying drawings.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily practice the present invention.
In an exemplary embodiment of the present invention, a ‘light emitting diode (LED) group’ means a set of LEDs in which a group of LEDs (or a plurality of light emitting cells) are connected in series, parallel, or series and parallel with each other, such that operations of the LEDs are controlled as one unit, depending on the control of an LED driving module (that is, the LEDs are turned on/off together with each other).
In addition, a ‘LED driving module’ means a module receiving an alternating current (AC) voltage to drive and control the LEDs, and although an exemplary embodiment in which the driving of the LEDs is controlled using a rectified voltage will be mainly described in the present specification, the present invention is not limited thereto, but should be generally and widely interpreted.
Further, a ‘first forward voltage level (Vf1)’ means a threshold voltage level that may drive a first LED group, a ‘second forward voltage level (Vf2)’ means a threshold voltage level that may drive first and second LED groups connected in series with each other, and a is ‘third forward voltage level (Vf3)’ means a threshold voltage level that may drive first to third LED groups connected in series with each other. That is, ‘an n-th forward voltage level (Vfn)’ means a threshold voltage level that may drive first to n-th LED groups connected in series with each other. Meanwhile, forward voltage levels of each LED group may be the same as each other, or different from each other, depending on the number/characteristics of LEDs configuring the corresponding LED group.
Further, a ‘sequential driving scheme’ means a driving scheme in which LED groups sequentially emit light depending on an increase in an applied input voltage and are sequentially turned off depending on a decrease in an applied input voltage, in the LED driving module receiving an input voltage of which a magnitude is changed over time to drive the LEDs.
Further, a ‘first stage driving section’ means a time period in which only a first LED group emits light, and a ‘second stage driving section’ means a time period in which only first and second LED groups emit light. Therefore, an ‘n-th stage driving section’ means a time period in which all of first to n-th LED groups emit light, but LED groups following an n+1-th LED group do not emit light.
Further, terms such as V1, V2, V3, . . . , t1, t2, . . . , T1, T2, T3, and the like, are used in order to represent any specific voltage, specific point in time, specific temperature, and the like, and are not used in order to represent absolute values. Instead, these terms are used in order to distinguish relative values from each other.
First, the LED illuminating apparatus 1000 may be configured to include a dimmer 100, an electromagnetic interference (EMI) filter 110, a rectifying unit 120, a surge protecting unit 130, a dimming level detecting unit 140, an LED driving module 200, and an LED light-emitting unit 300.
The dimmer 100 may be configured to receive an AC voltage (VAC) from an AC voltage source and control the received AC voltage (VAC) depending on a dimming level selected depending on a manipulation of a user, to generate and output the controlled AC power. The dimmer 100 may be one of a TRIAC dimmer controlling a phase of AC power using a TRIAC, a pulse width modulation (PWM) dimmer, an analog voltage dimmer changing an AC voltage, and dimmers equivalent thereto. That is, it is to be noted that the dimmer 100 may be any dimmer that may control the AC power depending on the selected dimming level to generate/output the controlled AC power and allow the selected dimming level to be detected by a dimming level detecting unit 140 described below, from the AC power controlled by the dimmer 100 (or a controlled rectified voltage generated by full-wave-rectifying the controlled AC power). Hereinafter, although the present invention will be described based on an exemplary embodiment in which the TRIAC dimmer is adopted as the dimmer 100, it will be obvious that the scope of the present invention is not limited thereto, but also includes exemplary embodiments in which one of various dimmers as described above is used as long as it includes the gist of the present invention.
In the case in which the dimmer 100 is implemented using the TRIAC dimmer as described above, the dimmer 100 may be configured to control the phase of the input AC power is based on the dimming level selected by a user (or selected automatically) to generate and output the phase-controlled AC voltage. Since the TRAIC dimmer adopts the technology well-known in the art, a detailed description thereof will be omitted. Although the dimmer 100 is included in one apparatus has been shown in
In the case in which the dimmer 100 is configured using the TRIAC dimmer, a TRIAC trigger current should be processed. Therefore, the LED illuminating apparatus 1000 may further include a trigger current maintaining circuit 105 connected between the dimmer 100 and the rectifying unit 120, to allow the TRIAC trigger current to flow to an AC power input or a rectified voltage output, or act as a dummy load. In
In addition, as described above, in the case in which the TRIAC dimmer is used as the dimmer 100, high frequency noise occurs at a turn-on point in time, due to a physical property of the TRIAC device. Since the high frequency noise may cause damage to the LED illuminating apparatus 1000, it is generally preferable to remove the high frequency noise. Therefore, the EMI filter 110 is provided between an output terminal of the dimmer 100 and an input terminal of the rectifying unit 120. The EMI filter 110 serves to attenuate the high is frequency noise of the phase-controlled AC voltage output from the dimmer 100. Since the EMI filter 110 adopts the technology well-known in the art, a detailed description thereof will be omitted.
The rectifying unit 120 serves to rectify the phase-controlled AC voltage output from the dimmer 100 to generate a driving voltage (VP) and output the generated driving voltage (VP). As the rectifying unit 120, one of various known rectifying circuits such as a full-wave rectifying circuit, a half-wave rectifying circuit, and the like, may be used. The driving voltage (VP) output from the rectifying unit 120 is output to the dimming level detecting unit 140, the LED driving module 200, and the LED light-emitting unit 300. In
The LED illuminating apparatus 1000 may further include the surge protecting unit 130 to protect the LED driving module 200 and the LED light-emitting unit 300 from an over-voltage and/or an over-current. The surge protecting unit 130 is connected to an output terminal of the rectifying unit 120 and is configured to serve to protect components of the LED illuminating apparatus 1000 from the over-voltage and/or the over-current. In
The LED light-emitting unit 300 may include a plurality of LED groups, and the LED groups included in the LED light-emitting unit 300 may sequentially emit light and may be sequentially turned off, depending on a control of the LED driving module 200. Although the LED light-emitting unit 300 including a first LED group 310, a second LED group 320, a third LED group 330, and a fourth LED group 340 is shown in
In addition, according to other exemplary embodiments, the first LED group 310, the second LED group 320, the third LED group 330, and the fourth LED group 340 may have the same forward voltage level or different forward voltage levels, respectively. For example, in the case in which the first LED group 310, the second LED group 320, the third LED group 330, and the fourth LED group 340 include different numbers of LED devices, respectively, the first LED group 310, the second LED group 320, the third LED group 330, and the fourth LED group 340 will have different forward voltage levels. On the other hand, for example, in the case in which the first LED group 310, the second LED group 320, the third LED group 330, and the fourth LED group 340 include the same number of LED devices, the first LED group 310, the second LED group 320, the third LED group 330, and the fourth LED group 340 will have the same forward voltage level.
The dimming level detecting unit 140 may be configured to receive the driving voltage (VP) output from the rectifying unit 120, detect a currently selected dimming level based on the received driving voltage (VP), and output the detected dimming level signal to the LED driving module 200. In more detail, the dimming level detecting unit 140 may be configured to average the driving voltage (VP), of which a level is changed over time, to detect the dimming level. As described above, since the dimmer 100 is configured to cut the phase of the AC voltage (VAC) depending on the selected dimming level, in the case in which the driving voltage (VP) is averaged, the currently selected dimming level may be detected. In the case in which the dimming level detecting unit 140 is configured in this scheme, a dimming level signal Adim corresponding to a specific dimming level output from the dimming level detecting unit 140 may be a DC signal having a constant voltage value. For example, in the case in which the dimming is level is 100%, the dimming level signal Adim corresponding to the dimming level is 2V, in the case in which the dimming level is 90%, the dimming level signal Adim corresponding to the dimming level is 1.8V, and in the case in which the dimming level is 50%, the dimming level signal Adim corresponding to the dimming level is 1V. A value and a range of the dimming level signal Adim corresponding to the specific dimming level may be changed by appropriately selecting values of circuit devices configuring the dimming level detecting unit 140. In
The dimming level detecting unit 140 may further include a voltage limiting circuit 142 to limit the received driving voltage (VP) to a maximum voltage or less. Generally, a maximum voltage level of the driving voltage (VP) supplied to the LED light-emitting unit 300 is significantly high. Therefore, in the case in which the dimming level is detected using the driving voltage (VP) and the detected dimming level is input to the LED driving module 200, there is a risk that the LED driving module 200 will be damaged. Therefore, in order to solve this problem, the dimming level detecting unit 140 may include the voltage limiting circuit 142 to limit the received driving voltage (VP) to a maximum voltage (for example, 15V) or less. In
The dimming level detecting unit 140 will be described in detail with reference to
The LED driving module 200 is configured to receive the driving voltage (VP) output from the rectifying unit 120, determine the magnitude of the received driving voltage (VP), and control sequential driving of the LED light-emitting unit 300 (more specifically, each of the LED groups 310 to 340 included in the LED light-emitting unit 300) depending on the determined magnitude of the driving voltage (VP). Generally, the maximum voltage level of the driving voltage (VP) supplied to the LED light-emitting unit 300 is significantly high. Therefore, in the case of using the driving voltage (VP) as it is, the LED driving module 200 may be damaged. In order to prevent this problem, the LED illuminating apparatus 1000 may include a driving voltage stabilizing unit 150 disposed between a driving voltage (VP) input node and a driving voltage input terminal of the LED illuminating apparatus 1000. Referring to
In addition, the LED driving module 200 may be configured to receive the dimming level signal Adim output from the dimming level detecting unit 140 and limit a maximum value of the LED driving current ILED, based on the received dimming level signal Adim. In more detail, the LED driving module 200 may be configured to determine an LED driving current reference value (Adim_Iref) that is dimming-controlled in proportion to the received dimming level signal Adim and perform a constant current control on the LED driving current ILED, based on the determined dimming-controlled LED driving current reference value (Adim_Iref). In the case in which a dimming control is performed in this scheme, a light emitting time of the LED light-emitting unit 300 is controlled by the driving voltage (VP) of which a phase is controlled (that is, of which a phase is cut depending on the dimming level), and a magnitude of the LED driving current ILED is controlled based on the detected dimming level, thereby displaying smooth dimming characteristics over an entire section of the dimming level. In addition, through the above-mentioned configuration, a non-uniform fluctuation phenomenon may be removed. A detail configuration and function of the LED driving module 200 will be described below with reference to
In addition, in
As shown in
The internal power generating unit 230 is configured to decrease and smooth the driving voltage VP to generate and supply internal DC power VCC for driving the LED driving module 200. The internal power generating unit 230 may be implemented by a smoothing circuit including a resistor and a capacitor.
The LED driving control unit 210 is configured to judge a voltage level of the driving voltage VP input from the rectifying unit 120 and control sequential driving of the LED groups 310 to 340, depending on the voltage level of the driving voltage V. In more detail, the LED driving control unit 210 performs a control operation, so that only the first current path P1 is connected and the other current paths are opened, such that only the first LED group 310 emits is light, in a first stage operation section in which the voltage level of the driving voltage VP is between a first forward voltage level Vf1 and a second forward voltage level Vf2. In addition, the LED driving control unit 210 performs a control operation, so that only the second current path P2 is connected and the other current paths are opened, such that the first and second LED groups 310 and 320 emit light, in a second stage operation section, in which the voltage level of the driving voltage VP is between the second forward voltage level Vf2 and a third forward voltage level Vf3. Similarly, the LED driving control unit 210 performs a control operation, so that only the third current path P3 is connected and the other current paths are opened, such that the first to third LED groups 310 to 330 emit light, in a third stage operation section, in which the voltage level of the driving voltage VP is between the third forward voltage level Vf3 and a fourth forward voltage level Vf4. In addition, the LED driving control unit 210 performs a control operation, so that only the fourth current path P4 is connected and the other current paths are opened, such that all of the first to fourth LED groups 310 to 340 emit light, in a fourth stage operation section, in which the voltage level of the driving voltage VP is the fourth forward voltage level Vf4 or more. Therefore, the LED driving control unit 210 is configured to control the sequential driving of the LED groups 310 to 340 depending on the voltage level of the driving voltage VP through the scheme described above.
The LED driving control unit 210 may be configured to determine the LED driving current reference value Iref that becomes a reference of a constant current control depending on the input dimming level signal Adim and output the determined LED driving current reference value Iref to the LED group driving units 220, in order to perform the dimming control function. Here, the LED driving current reference value Iref output from the LED driving control unit 210 becomes a reference value for performing a constant current control on the LED is driving current ILED in the LED group driving units 220. Here, more preferably, the LED driving control unit 210 may be configured to approximate first to fourth LED driving currents ILED1 to ILED4 to a sine wave, by setting a first driving current reference value Iref1, a second driving current reference value Iref2, a third driving current reference value Iref1, and a fourth driving current reference value Iref4 to be different from each other. As such, a waveform of the LED driving current may approximate to a waveform of the driving voltage VP, in order to improve power factor (PF) and total harmonic distortion (THD) characteristics. That is, a reference value may be set to sequentially rise from the first driving current reference value Iref1 of the first stage driving section, to the fourth driving current reference value Iref4 of the fourth stage driving section. When it is assumed that a dimming level of 100% is selected for explanation, the fourth driving current reference value Iref4 may be set to 100 mA, the third driving current reference value Iref3 may be set to any value between 80 to 95 mA, which is 80 to 95% of the fourth driving current reference value Iref4, the second driving current reference value Iref2 may be set to any value between 65 to 80 mA, which is 65 to 80% of the fourth driving current reference value Iref4, and the first driving current reference value Iref1 may be set to any value between 30 to 65 mA, which is 30 to 65% of the fourth driving current reference value Iref4.
Since the case in which the dimming level of 100% is selected has been assumed in the above-mentioned example, as the dimming level is changed, the first to fourth driving current reference values Iref1 to Iref4 will be determined depending on the changed dimming level, and newly determined first to fourth driving current reference values Iref1′ to Iref4′ will be output. In another exemplary embodiment, the fourth driving current reference value Iref4 may be a maximum LED driving current ILEDmax set depending on the resistance value of the maximum LED driving current setting resistor R5, and the first driving current reference value Iref1, the is second driving current reference value Iref2, and the third driving current reference value Iref3 may be reference values obtained by decreasing the fourth driving current reference value Iref4 in preset decrease ratios, respectively. Hereinafter, a driving current reference value in the case in which the dimming control function is enabled and the dimming level is not 100% is called a dimming-controlled driving current reference value (Adim_Iref), in order to be distinguished from a maximum driving current reference value (Iref), in the case in which the dimming level is 100% or in the case in which the dimming control function is disabled. A detailed description depending on a dimming level will be described below with reference to
The LED group driving units 220 are configured to connect or open each of the current paths P1 to P4 depending on the control of the LED driving control unit 210 and perform a constant current control on the LED driving current ILED. As shown in
The LED group driving units 222 to 228 are configured to perform a constant is current control function in addition to turn on/off control functions of the paths P1 to P4, respectively.
Referring to
The electronic switching device Q1 is configured to be turned on depending on a control of the LED driving control unit 210 to connect the first current path P1 and be turned off depending on a control of the LED driving control unit 210 to open the first current path P1. As the electronic switching device Q1, a bipolar junction transistor (BJT), a field effect transistor is (FET), or the like, may be used, and a kind of electronic switching device Q1 is not limited. In
A maximum first driving current reference value Iref1 output from the LED driving control unit 210 or a first driving current reference value Adim_Iref1 dimming-controlled is input as a reference value to a non-inverting input terminal of the operational amplifier OP1, and a voltage value across the sensing resistor Rsense1 (that is, a voltage value corresponding to the first LED driving current ILED1 flowing through the first current path P1) is input to an inverting input terminal of the operational amplifier OP″ The operational amplifier OP1 compares a voltage input through the non-inverting input terminal and a voltage input through the inverting input terminal and controls a gate voltage of the electronic switching device Q1 so that the first LED driving current ILED1 may be maintained as an input reference value, depending on a result of the comparison. As such, a constant current control function may be performed.
The second to fourth LED group driving units 224 to 228 may also include an electronic switching device, a sensing resistor, and a differential amplifier, similar to the first LED group driving unit 222.
Therefore, the second LED group driving unit 224 connects or opens the second current path P2 and performs a constant current control, so that the second LED driving current ILED2 may be maintained as an input reference value using a maximum second driving current reference value Iref2 output from the LED driving control unit 210 or a second driving current reference value Adim_Iref2 dimming-controlled as the reference value. Similarly, the third LED group driving unit 226 connects or opens the third current path P3 and performs a constant current control so that the third LED driving current ILED3 may be maintained as an input is reference value using a maximum third driving current reference value Iref1 output from the LED driving control unit 210 or a third driving current reference value Adim_Iref1 dimming-controlled as the reference value. Finally, the fourth LED group driving unit 228 connects or opens the fourth current path P4 and performs a constant current control so that the fourth LED driving current ILED4 may be maintained as an input reference value using a maximum fourth driving current reference value Iref4 output from the LED driving control unit 210 or a fourth driving current reference value Adim_Iref4 dimming-controlled as the reference value.
First, in
As shown in
Referring to
Next, at a point in time t2 in which the voltage level of the driving voltage VP further rises over time to arrive at a second forward voltage level Vf2, the first LED group driving unit 222 is turned off and the second LED group driving unit 224 is turned on, depending on a control of the LED driving control unit 210, such that the second current path P2 is connected. Therefore, the second LED driving current ILED2 flows through the second current is path P2 and the first and second LED groups 310 and 320 emit light. In this case, since the dimming level is 100%, the LED driving control unit 210 outputs the maximum second driving current reference value Iref2 as a reference value for a constant current control to the second LED group driving unit 224, and the second LED group driving unit 224 detects the second LED driving current ILED2 and performs a constant current control function so that the second LED driving current ILED2 may be maintained as the maximum second driving current reference value Iref2.
Similarly, at a point in time t3 in which the voltage level of the driving voltage VP further rises over time to arrive at a third forward voltage level Vf3, the second LED group driving unit 224 is turned off and the third LED group driving unit 226 is turned on, depending on a control of the LED driving control unit 210, such that the third current path P3 is connected. Therefore, the third LED driving current ILED3 flows through the third current path P3 and the first to third LED groups 310 to 330 emit light. In this case, since the dimming level is 100%, the LED driving control unit 210 outputs the maximum third driving current reference value Iref3 as a reference value for a constant current control to the third LED group driving unit 226, and the third LED group driving unit 226 detects the third LED driving current ILED3 and performs a constant current control function, so that the third LED driving current ILED3 may be maintained as the maximum third driving current reference value Iref3.
In addition, at a point in time t4 in which the voltage level of the driving voltage VP further rises over time to arrive at a fourth forward voltage level Vf4, the third LED group driving unit 226 is turned off and the fourth LED group driving unit 228 is turned on, depending on a control of the LED driving control unit 210, such that the fourth current path P4 is connected. Therefore, the fourth LED driving current ILED4 flows through the fourth current path is P4 and the first to fourth LED groups 310 to 340 emit light. In this case, since the dimming level is 100%, the LED driving control unit 210 outputs the maximum fourth driving current reference value Iref4 as a reference value for a constant current control to the fourth LED group driving unit 228, and the fourth LED group driving unit 228 detects the fourth LED driving current ILED4 and performs a constant current control function, so that the fourth LED driving current ILED4 may be maintained as the maximum fourth driving current reference value Iref4.
Meanwhile, at a point in time t5 in which the voltage level of the driving voltage VP arrives at a maximum value and then falls over time to become less than the fourth forward voltage level Vf4, the fourth LED group driving unit 228 is turned off and the third LED group driving unit 226 is turned on, depending on a control of the LED driving control unit 210, such that the third current path P3 is connected. Therefore, the third LED driving current ILED3 flows through the third current path P3 and the first to third LED groups 310 to 330 emit the light. In this case, as described above, the third LED group driving unit 226 detects the third LED driving current ILED3 and performs a constant current control function, so that the third LED driving current ILED3 may be maintained as the maximum third driving current reference value Iref3.
In addition, at a point in time t6 in which the voltage level of the driving voltage VP drops over time to become less than the third forward voltage level Vf3, the third LED group driving unit 226 is turned off and the second LED group driving unit 224 is turned on, depending on a control of the LED driving control unit 210, such that the second current path P2 is connected. Therefore, the second LED driving current ILED2 flows through the second current path P2 and the first and second LED groups 310 and 320 emit the light. In this case, as described above, the second LED group driving unit 224 performs a constant current control function, so that the second LED driving current ILED2 may be maintained as the maximum is second driving current reference value Iref2.
Finally, at a point in time t7 in which the voltage level of the driving voltage VP drops over time to become less than the second forward voltage level Vf2, the second LED group driving unit 224 is turned off and the first LED group driving unit 222 is turned on, depending on a control of the LED driving control unit 210, such that the first current path P1 is connected. Therefore, only the first LED group 310 emits the light, and the first LED group driving unit 222 performs a constant current control function so that the first LED driving current ILED1 may be maintained as the maximum first driving current reference value Iref1.
Next, in
Referring to
Since the voltage level of the driving voltage VP rises to the third forward voltage level Vf3 at the point in time t3, the third LED group driving unit 226 is turned on, such that the is third current path P3 is connected. Therefore, a third LED driving current ILED3′ flows through the third current path P3 and the first to third LED groups 310 to 330 emit the light. In this case, since the dimming level is 80%, the LED driving control unit 210 outputs a third driving current reference value Adim_Iref1 corresponding to the dimming level of 80% and dimming-controlled as a reference value for a constant current control to the third LED group driving unit 226. Here, the third driving current reference value Adim_Iref3 corresponding to the dimming level of 80% and dimming-controlled may be determined in various schemes. In an exemplary embodiment, the third driving current reference value Adim_Iref3 corresponding to the dimming level of 80% and dimming-controlled may be determined to be “a*(dimming level signal Adim corresponding to dimming level of 80%)*(maximum third driving current reference value Iref3)” (here, a indicates any constant allowing a light output or flux of the LED illuminating apparatus 1000 to become 80% of a maximum light output or flux).
Alternatively, in another exemplary embodiment, the third driving current reference value Adim_Iref1 corresponding to the dimming level of 80% and dimming-controlled may be determined to be “b*0.8*(maximum third driving current reference value Iref3)” (here, b indicates any constant allowing a light output or flux of the LED illuminating apparatus 1000 to become 80% of a maximum light output or flux). Alternatively, in still another exemplary embodiment, an equation or a graph for third driving current reference values Adim_Iref3 corresponding to a dimming level and dimming-controlled may be stored, and a third driving current reference value Adim_Iref3 dimming-controlled may be determined using the equation or is the graph depending on a detected dimming level. The third driving current reference value Adim_Iref3 dimming-controlled may be determined in various schemes other than the above-mentioned schemes, and it will be obvious to those skilled in the art that various modifications and alterations may be made without departing from the scope of the present invention as long as the third driving current reference value Adim_Iref3 dimming-controlled is determined in proportion to the dimming level. A first driving current reference value Adim_Iref1 dimming-controlled, a second driving current reference value Adim_Iref2 dimming-controlled, and a fourth driving current reference value Adim_Iref4 dimming-controlled may also be determined in the same scheme as the above-mentioned scheme.
At the point in time t4 in which the voltage level of the driving voltage VP further rises over time to arrive at the fourth forward voltage level Vf4, the third LED group driving unit 226 is turned off and the fourth LED group driving unit 228 is turned on, depending on a control of the LED driving control unit 210, such that the fourth current path P4 is connected. Therefore, a fourth LED driving current ILED4′ flows through the fourth current path P4 and the first to fourth LED groups 310 to 340 emit the light. In this case, the LED driving control unit 210 outputs the fourth driving current reference value Adim_Iref4 corresponding to the dimming level of 80% and dimming-controlled to the fourth LED group driving unit 228, and the fourth LED group driving unit 228 detects the fourth LED driving current ILED4′ and performs a constant current control function so that the fourth LED driving current ILED4′ may be maintained as the fourth driving current reference value Adim_Iref4 dimming-controlled.
At the point in time t5 in which the voltage level of the driving voltage VP arrives at the maximum value and then falls over time to become less than the fourth forward voltage level Vf4, the fourth LED group driving unit 228 is turned off and the third LED group driving is unit 226 is turned on, depending on a control of the LED driving control unit 210, such that the third current path P3 is connected. Therefore, a third LED driving current ILED3′ flows through the third current path P3 and the first to third LED groups 310 to 330 emit the light. In this case, as described above, the third LED group driving unit 226 detects the third LED driving current ILED3′ and performs a constant current control function, so that the third LED driving current ILED3′ may be maintained as the third driving current reference value Adim_Iref3 corresponding to the dimming level of 80% and dimming-controlled.
At the point in time t6 in which the voltage level of the driving voltage VP drops over time to become less than the third forward voltage level Vf3, the third LED group driving unit 226 is turned off and the second LED group driving unit 224 is turned on, depending on a control of the LED driving control unit 210, such that the second current path P2 is connected. Therefore, a second LED driving current ILED2′ flows through the second current path P2 and the first and second LED groups 310 and 320 emit the light. In this case, as described above, the second LED group driving unit 224 performs a constant current control function, so that the second LED driving current ILED2′ may be maintained as the second driving current reference value Adim_Iref2 corresponding to the dimming level of 80% and dimming-controlled.
At the point in time t7 in which the voltage level of the driving voltage VP drops over time to become less than the second forward voltage level Vf2, the second LED group driving unit 224 is turned off and the first LED group driving unit 222 is turned on, depending on a control of the LED driving control unit 210, such that the first current path P1 is connected. Therefore, only the first LED group 310 emits the light, and the first LED group driving unit 222 performs a constant current control function, so that the first LED driving current ILED1′ may be maintained as the first driving current reference value Adim_Iref1 corresponding to the dimming is level of 80% and dimming-controlled.
In
Referring to
Since the voltage level of the driving voltage VP rises to the fourth forward voltage level Vf4 at the point in time t5, the fourth LED group driving unit 228 is turned on, depending on a control of the LED driving control unit 210, such that the fourth current path P4 is connected. Therefore, a fourth LED driving current ILED4″ flows through the fourth current path P4 and the first to fourth LED groups 310 to 340 emit the light. In this case, the LED is driving control unit 210 outputs a fourth driving current reference value Adim_Iref4′ corresponding to the dimming level of 40% and dimming-controlled to the fourth LED group driving unit 228, and the fourth LED group driving unit 228 detects the fourth LED driving current ILED4″ and performs a constant current control function, so that the fourth LED driving current ILED4″ may be maintained as the fourth driving current reference value Adim_Iref4′ dimming-controlled.
At the point in time t5 in which the voltage level of the driving voltage VP arrives at the maximum value and then falls over time to become less than the fourth forward voltage level Vf4, the fourth LED group driving unit 228 is turned off and the third LED group driving unit 226 is turned on, depending on a control of the LED driving control unit 210, such that the third current path P3 is connected. Therefore, a third LED driving current ILED3″ flows through the third current path P3 and the first to third LED groups 310 to 330 emit the light. In this case, as described above, the third LED group driving unit 226 detects the third LED driving current ILED3″ and performs a constant current control function so that the third LED driving current ILED3″ may be maintained as a third driving current reference value Adim Iref3′ input from the LED driving control unit 210, corresponding to the dimming level of 40%, and dimming-controlled.
At the point in time t6 in which the voltage level of the driving voltage VP drops over time to become less than the third forward voltage level Vf3, the third LED group driving unit 226 is turned off and the second LED group driving unit 224 is turned on, depending on a control of the LED driving control unit 210, such that the second current path P2 is connected. Therefore, a second LED driving current ILED2″ flows through the second current path P2 and the first and second LED groups 310 and 320 emit the light. In this case, as described above, the is second LED group driving unit 224 performs a constant current control function so that the second LED driving current ILED2″ may be maintained as a second driving current reference value Adim_Iref2′ corresponding to the dimming level of 40% and dimming-controlled.
At the point in time t7 in which the voltage level of the driving voltage VP drops over time to become less than the second forward voltage level Vf2, the second LED group driving unit 224 is turned off and the first LED group driving unit 222 is turned on, depending on a control of the LED driving control unit 210, such that the first current path P1 is connected. Therefore, only the first LED group 310 emits the light, and the first LED group driving unit 222 performs a constant current control function, so that the first LED driving current ILED1″ may be maintained as a first driving current reference value Adim_Iref1′ corresponding to the dimming level of 40% and dimming-controlled.
As set forth above, according to exemplary embodiments of the present invention, an AC driven LED illuminating apparatus capable of displaying smooth dimming characteristics is over an entire section of a dimming level may be provided.
In addition, according to the present invention, an AC driven LED illuminating apparatus capable of displaying excellent dimming characteristics by interworking with a TRIAC dimmer configured to perform a dimming control using a phase control may be provided.
Further, according to the present invention, an AC driven LED illuminating apparatus capable of overcoming a fluctuation phenomenon when LED groups are sequentially driven may be provided.
Moreover, according to the present invention, an AC driven LED illuminating apparatus capable of more efficiently performing a dimming control using both of a driving voltage phase-controlled depending on a dimming level and an LED driving current of which a magnitude is adjusted may be provided.
Furthermore, according to the present invention, an AC driven LED illuminating apparatus capable of removing an irregular fluctuation phenomenon by maintaining an LED driving current for 1-stage driving as a predetermined value or more even at a minimum dimming level may be provided.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0118823 | Oct 2013 | KR | national |
This application is a continuation of U.S. patent application Ser. No. 14/507,347, filed on Oct. 6, 2014, and claims priority from and the benefit of Korean Patent Application No. 10-2013-0118823, filed on Oct. 4, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8102167 | Irissou et al. | Jan 2012 | B2 |
| 8115419 | Given et al. | Feb 2012 | B2 |
| 8203276 | Shackle et al. | Jun 2012 | B2 |
| 8299724 | Huynh | Oct 2012 | B2 |
| 8536798 | Matsuda et al. | Sep 2013 | B2 |
| 8581517 | Kuo et al. | Nov 2013 | B2 |
| 8624514 | Kang | Jan 2014 | B2 |
| 8723439 | Leung et al. | May 2014 | B2 |
| 8766550 | Yoon et al. | Jul 2014 | B1 |
| 8823266 | Qin | Sep 2014 | B2 |
| 8901841 | Choi et al. | Dec 2014 | B2 |
| 8947016 | Melanson et al. | Feb 2015 | B2 |
| 9000680 | Melanson | Apr 2015 | B2 |
| 9078327 | Livschitz | Jul 2015 | B2 |
| 9220143 | Jung | Dec 2015 | B2 |
| 20120319610 | Yoshinaga | Dec 2012 | A1 |
| 20130141008 | Chang et al. | Jun 2013 | A1 |
| Number | Date | Country |
|---|---|---|
| 2584866 | Apr 2013 | EP |
| 2004-327152 | Nov 2004 | JP |
| 2011-077037 | Apr 2011 | JP |
| 2011-113711 | Jun 2011 | JP |
| 2012-069308 | Apr 2012 | JP |
| 2012-165642 | Aug 2012 | JP |
| 2013-020931 | Jan 2013 | JP |
| 2013-033651 | Feb 2013 | JP |
| 2013-037837 | Feb 2013 | JP |
| 2013-118164 | Jun 2013 | JP |
| 2012168827 | Dec 2012 | WO |
| Entry |
|---|
| Extended European Search Report issued on May 12, 2015, in European Patent Application No. 14186988.3. |
| Non-Final Office Action issued on Aug. 28, 2015, in U.S. Appl. No. 14/507,347. |
| Notice of Allowance issued on Jan. 15, 2016, in U.S. Appl. No. 14/507,347. |
| Number | Date | Country | |
|---|---|---|---|
| 20160249429 A1 | Aug 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14507347 | Oct 2014 | US |
| Child | 15142568 | US |
