CN103889102A - Load driving device and driving method thereof - Google Patents
Load driving device and driving method thereof Download PDFInfo
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- CN103889102A CN103889102A CN201210566348.8A CN201210566348A CN103889102A CN 103889102 A CN103889102 A CN 103889102A CN 201210566348 A CN201210566348 A CN 201210566348A CN 103889102 A CN103889102 A CN 103889102A
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Abstract
A load driving apparatus and a driving method thereof. The load driving device receives a direct current input voltage and provides a direct current output voltage to the light emitting diode load in response to the grid pulse width modulation signal. The control chip in the load driving device is configured to: providing a gate pulse width modulation signal having a first default duty cycle during a bright operation of the dimming operation to turn the light emitting diode load fully on in response to the dc output voltage; and during a dark operation period of the dimming operation, providing a gate pulse width modulation signal with a second default duty cycle to enable the light emitting diode load to be weakly turned on in response to the direct current output voltage, wherein the second default duty cycle is smaller than the first default duty cycle, and the current of the light emitting diode load during the light operation period is larger than the current of the light emitting diode load during the dark operation period.
Description
Technical field
The invention relates to a kind of load drive device, and relate to especially a kind of light emitting diode drive device and driving method thereof.
Background technology
In traditional light-emitting diode (Light-emitting diodes, LED) drive unit, generally formed by the circuit of control chip, power switch and plug-in circuit etc.Wherein, control chip can provide and drive signal to carry out power switched switch, luminous so that LED is able to the electric current that produces according to the switching of power switch.With existing LED light modulation (dimming) technology, in order to reach high-contrast degree, general drive unit all adopts pulse width modulation (Pulse Width Modulation, PWM) light regulating technology, its light modulation principle is responsibility cycle (Dutycycle) length by adjusting PWM dim signal, control the complete bright and complete dark time scale of LED, to reach the object of light modulation.
Generally apply in LED illumination, provide voltage to start LED drive unit, after LED drive unit starts, the energy feedback just must fetch part LED work time is regarded power supply to LED drive unit.But, when LED light modulation is under complete dark situation, the bright time of LED shortens, and the relative time that LED drive unit can be provided and energy tail off, therefore during LED is entirely dark, cause the control chip in LED drive unit cannot work because power supply is not enough, generally speaking, must be by external large electric capacity to provide power supply to operate to control chip, with support tide over LED complete dark during, if but capacitance deficiency, therefore LED drive circuit still can quit work.In addition, increasing electric capacity not only can increase process costs also can increase the required area of printed circuit board (PCB) (Printed circuit board, PCB).
Summary of the invention
The invention provides a kind of load drive device, it can continue according to different light modulation operating period the PM signal of its corresponding responsibility cycle of output, effectively to reach the object of light modulation, also can avoid load drive device during complete dark because of the not enough problem that cannot operate of supply of electric power.
The invention provides a kind of load drive device, comprise a power-switching circuit and a control chip.It is configured to receive DC input voitage power-switching circuit, and reacts on grid pulse-width modulation signal and provide VD to LED load.Control chip couples power-switching circuit, and operate under VD, control chip is configured to: in the bright operating period of light modulation operation, provide the grid pulse-width modulation signal with the first acquiescence responsibility cycle, to cause LED load to react on VD and standard-sized sheet; And the dark operating period operating in light modulation, the grid pulse-width modulation signal with the second acquiescence responsibility cycle is provided, faintly open to cause LED load to react on VD, wherein, the second acquiescence responsibility cycle is slight in fact the first acquiescence responsibility cycle, wherein, LED load is greater than in fact the electric current of LED load in dark operating period at the electric current of bright operating period.
The invention provides a kind of method that load drives, be included in a bright operating period of a light modulation operation, provide the grid pulse-width modulation signal with one first acquiescence responsibility cycle, to cause LED load to react on VD and standard-sized sheet; And the dark operating period operating in light modulation, the grid pulse-width modulation signal with one second acquiescence responsibility cycle is provided, faintly open to cause LED load to react on VD, wherein, the second acquiescence responsibility cycle is slight in fact the first acquiescence responsibility cycle, wherein, LED load is greater than in fact the electric current of LED load in dark operating period at the electric current of bright operating period.
In one embodiment of this invention, above-mentioned control chip also comprises a power supply pin, a grounding leg position and an output pin position.Control chip receives DC input voitage by power supply pin, and DC input voitage is changed on operating power pin position, produce an operating power.Grounding leg position is in a quick condition.Output pin position by operating power in order to produce pulse-width modulation signal to control the running of power-switching circuit.
In one embodiment of this invention, above-mentioned control chip also comprises a compensation pin position.Control chip, by compensation pin position, is adjusted the responsibility cycle of pulse-width modulation driving signal with the voltage that affords redress.
In one embodiment of this invention, above-mentioned control chip also comprises a sensing pin position.Control chip reacts on the electric current of the current sensing circuit of flowing through by sensing pin position, and adjusts the responsibility cycle of pulse-width modulation driving signal.
In one embodiment of this invention, above-mentioned control chip also comprises a detecting pin position, and control chip is via detecting pin position in order to react on the conducting state of a direct voltage generation unit, and then adjustment pulse-width modulation drives the responsibility cycle of signal.
In one embodiment of this invention, above-mentioned power-switching circuit is a voltage dropping power supply change-over circuit, and this voltage dropping power supply change-over circuit comprises a power switch, a filter circuit and a power taking feedback circuit.Power switch has first end, the second end and control end, and the first end of power switch receives DC input voitage, and the second end of power switch couples earthing potential, and the control end of power switch couples output pin position to receive pulse-width modulation driving signal.Filter circuit is coupled between grounding leg position and light-emitting diodes pipe string, produces to determine electric current and drive light-emitting diodes pipe string in order to react on the switching of power switch.Power taking feedback circuit is coupled to the anode tap of power supply pin and light-emitting diodes pipe string, in order to provide a feedback electric current to power supply pin.
In one embodiment of this invention, above-mentioned power-switching circuit also comprises a frequency setting resistance.The first end of frequency setting resistance couples output pin position, and the second end of frequency setting resistance couples the second end of power switch, reacts on the resistance value of frequency setting resistance and sets pulse-width modulation and drive the frequency of signal.
In one embodiment of this invention, above-mentioned power-switching circuit also comprises a current sensing resistor.The first end of this current sensing resistor couples grounding leg position, and the second end of current sensing resistor couples the second end of power switch.
In one embodiment of this invention, above-mentioned power-switching circuit also comprises a compensating circuit.This compensating circuit couples between compensation pin position and grounding leg position.
In one embodiment of this invention, above-mentioned filter circuit also comprises an inductance and an electric capacity.The first end of this inductance couples grounding leg position, and its second end couples the anode tap of light-emitting diodes pipe string.The first end of this electric capacity couples the second end of inductance and the anode tap of light-emitting diodes pipe string, and its second end couples earthing potential.
In one embodiment of this invention, above-mentioned power-switching circuit also comprises a bleeder circuit, bleeder circuit reacts on direct voltage generation unit and obtains a detecting voltage, and relatively detects voltage and one with reference to detecting voltage, to obtain the conducting state of direct voltage generation unit.
Based on above-mentioned, the present invention is by the dark operating period of LED light modulation, continue the less pulse width modulation signal of output responsibility cycle, therefore in dark operating period, still there are enough power supplys to be supplied to LED drive unit to use, can not quit work because power supply is not enough, do not need additionally to strengthen electric capacity and go to support this time, therefore can reduce costs the area that yet can dwindle printed circuit board (PCB) (Printed circuitboard, PCB) yet.
Brief description of the drawings
For above-mentioned feature and advantage of the present invention can be become apparent, special embodiment below, and coordinate accompanying drawing to be described in detail below, wherein:
Fig. 1 is the block schematic diagram according to the load drive device of one embodiment of the invention.
Fig. 2 is the circuit diagram according to the load drive device of one embodiment of the invention.
Fig. 3 is the circuit diagram coupling according to power-switching circuit of the present invention and a direct current voltage generation circuit 300.
Fig. 4 is the light modulation mode chart according to the pulse width modulation of one embodiment of the invention.
Embodiment
Fig. 1 is the block schematic diagram according to the load drive device of one embodiment of the invention.In the present embodiment, load drive device 100 is at least suitable for driving light-emitting diodes pipe string 130.Please refer to Fig. 1, load drive device 100 comprises power-switching circuit 120 and control chip 110.Power-switching circuit 120 couples light-emitting diodes pipe string 130.Control chip 110 couples power-switching circuit 110, in order to control the running of power-switching circuit 120.Under the structure of the power-switching circuit 120 illustrating at Fig. 1, pulse width modulation (the Pulse Width Modulation being provided by the output pin position PIN_O of control chip 110 is provided power-switching circuit 120, PWM) signal S_PWM and switch start or cut-off power-switching circuit 120, drive light-emitting diodes pipe string 130 for DC input voitage VCC.
Embodiments of the present invention please refer to Fig. 2 in order further to illustrate, wherein, Fig. 2 is the circuit diagram according to the load drive device of one embodiment of the invention.
Please refer to Fig. 2, in the present embodiment, load drive device 100 comprises power-switching circuit 120, control chip 110.With regard to power-switching circuit 120 for regard to the structure of voltage dropping power supply change-over circuit, power-switching circuit 120 comprises diverter switch SW, Schottky diode SD, frequency setting circuit Ckt_Freq, current sensing circuit Ckt_A, filter circuit Ckt_Ftr, power taking feedback circuit Ckt_Fb, compensating circuit Ckt_Com, bleeder circuit Ckt_Dv (do not illustrate, remark additionally in Fig. 3) and resistance R 1, R6.Wherein, control chip 110 receives DC input voitage VCC via power supply pin PIN_V, and be enabled under DC input voitage VCC, and control chip 110 via output pin position PIN_O output pulse width modulation drive signal S_PWM to use the running of controlling power-switching circuit 120, to drive light-emitting diodes pipe string 130, and carry out light modulation operation.In the present embodiment, power-switching circuit 120 is a buck power-switching circuit (buck power conversion circuit).
Please refer to Fig. 3, Fig. 3 is the circuit diagram coupling according to power-switching circuit of the present invention and a direct current voltage generation circuit 300.Referring to Fig. 2 and Fig. 3, the direct voltage of the present embodiment produces circuit 300 can pass through an AC power 310, a diverter switch 315, an electromagnetic interference (electromagnetic interference, EMI) structure of filter 320 and a bridge rectifier 325 realizes, but the present invention is not as limit.In addition, direct voltage produces circuit 300 and also comprises a direct current modulator 330, and wherein direct voltage produces circuit 300 and can provide power-switching circuit 120 and the required DC input voitage VCC of control chip 110 by direct current modulator 330.
Produce at this direct voltage under the structure of circuit 300, control chip 110 can react on that direct voltage produces the conducting state of diverter switch 315 in circuit 300 and the responsibility cycle ON/OFF ratio of adjusting exported pulse-width modulation and drive signal S_PWM.
In more detail, control chip 110 also comprises a detecting pin position PIN_D, this detecting pin position PIN_D is coupled to the bleeder circuit Ckt_Dv of power-switching circuit 120, make control chip 110 react on the dividing potential drop of detecting voltage end Vout by bleeder circuit Ckt_Dv, to obtain a corresponding detecting voltage T1, and produce the conducting state of diverter switch 315 in circuit 300 with acquisition direct voltage with reference to detecting voltage by relatively detecting voltage T1 and.Therefore, control chip 110 can produce according to direct voltage the conducting state of diverter switch 315 in circuit 300, for example: the number of times of diverter switch 315 conductings, and the responsibility cycle ON/OFF ratio of control chip 110 and then the operation of adjustment pulse-width modulation, and so as to changing the required brightness of light-emitting diodes pipe string 130.Wherein, the brightness of light-emitting diodes pipe string 130 can correspond to the required electric current I _ LED size of the light-emitting diodes pipe string 130 of flowing through.
For example, when the number of times of diverter switch 315 conductings is one time, the responsibility cycle ON/OFF ratio of its corresponding pulse-width modulation operation is 75%ON, 25%OFF, when the number of times of diverter switch 315 conductings is secondary, the responsibility cycle ON/OFF ratio of its corresponding pulse-width modulation operation is 50%ON, 50%OFF.But the embodiment that upper number is adjusted the responsibility cycle ratio of pulse-width modulation operation only belongs to design alternative, but not as restriction.
In addition, bleeder circuit Ckt_Dv can utilize resistance R 7, R8 to carry out dividing potential drop to obtain corresponding detecting voltage with the detecting voltage end Vout that the structure of capacitor C 4 produces circuit 300 to direct voltage, and utilize capacitor C 4 detecting voltage to be carried out to the action of voltage stabilizing, but the structure of bleeder circuit Ckt_Dv is not limited to the execution mode that Fig. 2 illustrates.
Please return the explanation of Fig. 2, power-switching circuit 120 receives above-mentioned direct voltage and produces the DC input voitage VCC of circuit output, and power-switching circuit 120 also comprises Zener diode ZD1, ZD3 and capacitor C 3.The anode tap of Zener diode ZD1 is coupled to output node Nout, and the cathode terminal of Zener diode ZD1 couples earthed voltage GND, in order to protect the voltage stabilization of node Nout.The anode tap of Zener diode ZD3 is coupled to DC input voitage VCC by resistance R 1, and the cathode terminal of Zener diode ZD3 couples earthed voltage GND.Capacitor C 3 couples between DC input voitage VCC and earthed voltage GND by resistance R 1.Therefore, control chip 110 can receive stable DC input voitage VCC with Zener diode ZD3 by capacitor C 1.
In power-switching circuit 120, also comprise a power taking feedback circuit Ckt_Fb, be coupled between the power supply pin PIN_V and output node Nout of control chip 110, power taking feedback circuit Ckt_Fb provides control chip 110 required operating voltage in can be during driving light-emitting diodes pipe string 130, to replace the DC input voitage VCC that control chip 110 power supplys are provided originally.At this, the feedback path that power taking feedback circuit Ckt_Fb can consist of serial connection Zener diode ZD2, resistance R 2 and diode D1 is realized, but the present invention does not disclose and is limited with this.
In power-switching circuit 120, also comprise a current sensing circuit Ckt_A, couple the sensing pin position PIN_S of control chip 110, current sensing circuit Ckt_A can react on the electric current of the current sensing circuit Ckt_A that flows through, and adjusts the responsibility cycle of the pulse-width modulation driving signal S_PWM of the output pin position PIN_O output of control chip 110.More specifically, control chip 110 reacts on the electric current of the current sensing circuit Ckt_A that flows through, is the electric current I _ LED size that drives light-emitting diodes pipe string 130.That is to say, in the case of the resistance of light-emitting diodes pipe string 130 is constant, the electric current I _ LED of the light-emitting diodes pipe string 130 of flowing through is along with the voltage of node Nout changes.
Particularly, current sensing circuit Ckt_A can realize by the structure of resistance, at this current sensing circuit Ckt_A to comprise that resistance R 3 is as example.Specifically, the first end of resistance R 3 couples sensing pin position PIN_S, and the second end of resistance R 3 couples grounding leg position PIN_G.It should be noted that, current sensing circuit Ckt_A of the present invention is not limited only to realize with the structure of resistance, although in the present embodiment to be disposed at resistance R 3 between node N1 and NG as example, but, anyly cause pressure drop and make the circuit element of grounding leg position PIN_G and the structure all can be in order to replace resistance R 3, the present invention be as limit.
In power-switching circuit 120, power switch SW has first end, the second end and control end, its first end receives DC input voitage VCC, its second end couples earthing potential GND via node N1 and Schottky diode SD, and its control end output pin position PIN_0 of coupling control chip 110 drives signal S_PWM with the pulse-width modulation that receives control chip 110 and exported.Therefore, power switch SW can react on that pulse-width modulation that control chip 110 provides drives signal S_PWM and switched conductive or cut-off make power-switching circuit 120 to drive light-emitting diodes pipe string 130 according to the switching of power switch SW and DC input voitage VCC.
In power-switching circuit 120, also comprise that a filter circuit Ckt_Ftr is coupled between node NG (being equal to the grounding leg position PIN_G that couples control chip 110) and light-emitting diodes pipe string 130, produce in order to react on the switching of power switch SW and determine electric current and drive light-emitting diodes pipe string 130.In the present embodiment, filter circuit Ckt_Ftr realizes with inductance L 1 and the structure of capacitor C 1.Furthermore, the first end of the inductance L 1 of filter circuit Ckt_Ftr couples node NG, and its second end couples output node Nout (being equal to the anode tap of light-emitting diodes pipe string 130), and the first end of the capacitor C 1 of filter circuit Ckt_Ftr couples the second end and the output node Nout of inductance L 1, and its second end couples earthing potential GND.Wherein, 1 of inductance L 1 and capacitor C can be in order to provide filter function to determine electric current and drive light-emitting diodes pipe string 130 to produce.
With regard to power switch SW and filter circuit Ckt_Ftr, the pulse-width modulation providing according to control chip 110 as power switch SW drives signal S_PWM and when conducting, power-switching circuit 120 can provide the stable bias voltage of node N1, the energy storage because inductance L 1 is reacted on the voltage of node N1, and according to this generation current I_LED to drive light-emitting diodes pipe string 130; The driving signal providing according to control chip 110 as power switch SW and while ending, 1 of inductance L discharges electric energy and continues to produce drive current I_LED.
In the present embodiment, the configuration of described Schottky diode SD, inductance L 1 and capacitor C 1 is all to belong to design alternative.In other words, in other embodiments, this area knows that the knowledgeable can realize by other voltage stabilizing element or voltage regulator circuit structure the function of Schottky diode SD conventionally, and also can configure to realize inductance L 1 and the function of capacitor C 1 in power-switching circuit 120 by other filter element, the present invention is not limited to the configuration that Fig. 1 illustrates.
On the other hand, the grounding leg position PIN_G of control chip 110 is coupled to node NG, and reference voltage level using the voltage quasi position of node NG as control chip 110.Specifically, due to during power switch SW conducting, power-switching circuit 120 will produce the electric current of the power switch SW that flows through, node N1, resistance R 3 and inductance L 1, that is the sense of current is the electric current of node N1 to node NG.Therefore, no matter the voltage quasi position of node N1 why, or the size of current of the resistance R 3 of flowing through why, and the voltage quasi position of node NG all will react on the pressure drop of resistance R 3 and is less than the voltage quasi position of node N1.Thus, the voltage quasi position of node NG should be less than the voltage quasi position of arbitrary node in power-switching circuit 120, and any node that makes the pin position of control chip 110 each correspondences no matter be coupled to power-switching circuit 120 all cannot have the voltage quasi position lower than grounding leg position PIN_G.
Furthermore, because the grounding leg position PIN_G of control chip 110 is in quick condition (floating), therefore make grounding leg position PIN_G have the minimum voltage level in control chip 110.Therefore, in control chip 110 by the reverse conduction problem that can not produce between pin position.In addition, grounding leg position PIN_G represents grounding leg position PIN_G voltage quasi position in quick condition (is flowed through SW to R3 by VCC by the electric current source according to the resistance R 3 of flowing through, or by the afterflow of L1 electric current) and change, and so as to being maintained at the minimum voltage level in control chip 110.
In addition, the output pin position PIN_O of control chip 110 couples frequency setting circuit Ckt_Freq, sets the frequency of pulse-width modulation driving signal S_PWM in order to react on the electrical characteristic of frequency setting circuit CKt_Freq.In the present embodiment, frequency setting circuit Ckt_Freq can realize by the structure of resistance, at this frequency setting circuit Ckt_Freq taking a resistance R 4 as example, the first end of resistance R 4 couples output pin position PIN_O, and its second end is coupled to node N1, wherein designer can set accordingly by the resistance value of adjusting resistance R4 the frequency of pulse-width modulation driving signal S_PWM.But frequency setting circuit Ckt_Freq of the present invention is not limited only to realize with the structure of resistance.
Fig. 4 is the light modulation mode chart according to the pulse width modulation of one embodiment of the invention.Referring to Fig. 2 and Fig. 4, in the present embodiment, transverse axis is the time, the top longitudinal axis is control end voltage VG, namely received pwm signal (S_PWM) voltage value of the control end of power switch SW in power-switching circuit 120 described in key diagram 2 contents, top longitudinal axis collocation transverse axis can presentation graphs 2 described in power-switching circuit 120 power switch cut frequency.And bottom longitudinal axis collocation transverse axis can be expressed as the PWM light modulation operation of control chip 110 inside, transverse axis can be divided into bright operating period 410 and dark operating period 420.First, control chip 110 reacts on direct voltage by bleeder circuit Ckt_Dv and produces the dividing potential drop of detecting voltage end Vout in circuit 300, produce the conducting state of diverter switch 315 in circuit 300 to obtain direct voltage, and then the responsibility cycle ON/OFF ratio of adjustment PWM light modulation operation, and so as to changing the required brightness of light-emitting diodes pipe string 130, wherein, the responsibility cycle ON/OFF ratio of PWM light modulation operation determines the ratio of bright operating period 410 and dark 420 times of operating period.
In addition, in order to make the present invention make light-emitting diodes pipe string 130 reach required brightness during different operating, bright operating period 410 in the present embodiment and dark operating period 420, control chip 110 is exported respectively the pwm signal of different responsibility cycle, to adjust the electric current I _ LED of the light-emitting diodes pipe string 130 of flowing through.
Particularly, when load drive device 100 is during in bright operating period 410, pass through to receive DC input voitage VCC for startup by control chip 110, and after control chip 110 starts, output has the pwm signal of the first pulse duration 415, and provide control chip 110 required operating voltage by node Nout via power taking feedback circuit Ckt_Fb, to replace DC input voitage VCC.But, when load drive device 100 is during in dark operating period 420, continue output by control chip 110 and there is the pwm signal that has the second pulse duration 425, provide control chip 110 required minimum operation voltage to maintain output node Nout via power taking feedback circuit Ckt_Fb, be unlikely and decommission so that control chip 110 can continue to possess power supply.Wherein, in dark operating period 420 the second pulse duration 425 of pwm signal much smaller than the first pulse duration 415 of pwm signal in bright operating period 410.Also because the large I of pulse duration of pwm signal corresponds to the size of current of the light-emitting diodes pipe string 130 of flowing through, therefore, flow through the electric current of light-emitting diodes pipe string 130 much larger than at dark operating period light-emitting diodes pipe string electric current of 130 in bright operating period.
In sum, the load drive device that the present invention proposes is except in the bright operating period of LED light modulation, export the pulse width modulation signal of general responsibility cycle, in the dark operating period of LED light modulation, continue the pulse width modulation signal of the small responsibility cycle of output, therefore, in this dark operating period, still there are enough power supplys to be supplied to LED drive unit to use, can not quit work because power supply is not enough, do not need additionally to strengthen electric capacity and go to support this time yet, therefore can reduce costs and also can dwindle printed circuit board (PCB) (Printed circuit board, PCB) area.
Although the present invention discloses as above with embodiment; so it is not in order to limit the present invention; under any, in technical field, have and conventionally know the knowledgeable; without departing from the spirit and scope of the present invention; when doing a little change and retouching, therefore protection scope of the present invention is when being as the criterion of defining depending on accompanying claim scope.
Claims (12)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201210566348.8A CN103889102B (en) | 2012-12-24 | 2012-12-24 | Load driving device and driving method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210566348.8A CN103889102B (en) | 2012-12-24 | 2012-12-24 | Load driving device and driving method thereof |
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| CN103889102A true CN103889102A (en) | 2014-06-25 |
| CN103889102B CN103889102B (en) | 2016-04-27 |
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| CN201210566348.8A Expired - Fee Related CN103889102B (en) | 2012-12-24 | 2012-12-24 | Load driving device and driving method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108572755A (en) * | 2017-03-13 | 2018-09-25 | 义隆电子股份有限公司 | Pointing input device, signal processing device thereof and pointing input module |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201134970Y (en) * | 2007-12-27 | 2008-10-15 | 李东方 | Bi-frequency pulsewidth adjustable light regulating electronic ballast |
| KR20090125927A (en) * | 2008-06-03 | 2009-12-08 | 삼성전기주식회사 | Driving circuit of light emitting element |
| CN202261964U (en) * | 2011-09-13 | 2012-05-30 | 昂宝电子（上海）有限公司 | LED drive circuit |
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2012
- 2012-12-24 CN CN201210566348.8A patent/CN103889102B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201134970Y (en) * | 2007-12-27 | 2008-10-15 | 李东方 | Bi-frequency pulsewidth adjustable light regulating electronic ballast |
| KR20090125927A (en) * | 2008-06-03 | 2009-12-08 | 삼성전기주식회사 | Driving circuit of light emitting element |
| CN202261964U (en) * | 2011-09-13 | 2012-05-30 | 昂宝电子（上海）有限公司 | LED drive circuit |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108572755A (en) * | 2017-03-13 | 2018-09-25 | 义隆电子股份有限公司 | Pointing input device, signal processing device thereof and pointing input module |
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| CN103889102B (en) | 2016-04-27 |
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