WO2014110840A1 - Led调光驱动装置及方法 - Google Patents

Led调光驱动装置及方法 Download PDF

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Publication number
WO2014110840A1
WO2014110840A1 PCT/CN2013/070857 CN2013070857W WO2014110840A1 WO 2014110840 A1 WO2014110840 A1 WO 2014110840A1 CN 2013070857 W CN2013070857 W CN 2013070857W WO 2014110840 A1 WO2014110840 A1 WO 2014110840A1
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WIPO (PCT)
Prior art keywords
circuit
comparator
led
driving device
dimming
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PCT/CN2013/070857
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English (en)
French (fr)
Inventor
胡安乐
杨翔
张华�
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TCL China Star Optoelectronics Technology Co Ltd
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Shenzhen China Star Optoelectronics Technology Co Ltd
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Priority to US13/813,450 priority Critical patent/US9370056B2/en
Publication of WO2014110840A1 publication Critical patent/WO2014110840A1/zh
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/38—Switched mode power supply [SMPS] using boost topology
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

  • the invention relates to a light emitting diode (Light Emitting Diode,
  • the invention relates to the field of LED technology, and in particular to an LED dimming driving device and method.
  • FIG. 1 is a block diagram of a conventional LED dimming driving circuit. As shown in the figure, the driving principle is mainly to use the voltage source 10 to provide the working voltage to one LED path. 20, the LED path 20 is connected to a switch circuit 30, and a current detector 40 is connected in series after the switch circuit 30.
  • the current detector 40 is usually a resistor that uses a voltage drop generated by a current flowing through the resistor to detect the amount of current.
  • the current detector 40 is connected to a comparison circuit 50, and the voltage obtained by the current detector 40 is compared with the triangular wave 42. When the voltage of the triangular wave 42 is greater than the voltage obtained by the current detector 40, the comparison circuit 161 outputs a high value. Level signal, and vice versa, output a low level signal to generate a pulse width modulation (Pulse) Width Modulation, PWM) Signal 52 is used to control the communication or blocking of the switching circuit 30.
  • PWM pulse width modulation
  • variable resistor As the current detector 40. By changing the resistance of the variable resistor, the voltage obtained by the current detector 40 at the same current is lowered.
  • the comparison circuit 50 can increase or decrease the duty cycle of the PWM signal 52, thereby changing the luminance of the LED path 20.
  • Another means is to change the amplitude of the triangular wave 42. Under the condition of the fixed resistance value, the duty ratio of the PWM signal 52 can also be changed to achieve the purpose of dimming.
  • the switching transistor Q2 in the switching circuit 30 when the switching transistor Q2 in the switching circuit 30 is turned off, the gate signal GATE received by the field effect transistor Q1 in the voltage source 10 implemented by the boost circuit is at a low level. At this time, the LED path 20 is extinguished, so that the current flowing through the inductor L drops sharply, causing the inductor core to vibrate and generate a large noise. At the same time, the voltage source 10 also generates large electromagnetic interference.
  • An object of the present invention is to provide an LED dimming driving device to solve the problem of noise and electromagnetic interference generated when the LED path is extinguished in the prior art.
  • Another object of the present invention is to provide an LED dimming driving method for solving the problem of noise and electromagnetic interference generated when the LED path is extinguished.
  • a preferred embodiment of the present invention provides an LED dimming driving device including a dimming switch that controls an LED path to be connected or blocked.
  • the LED dimming driving device further includes: a boosting circuit electrically connected to the LED path; a comparator electrically connected to the boosting circuit, the comparator receiving a triangular wave signal to generate a PWM signal, PWM signal controls the boost circuit; and RC (Resistor The circuit is electrically connected to the comparator, and the RC circuit is configured to output a charging curve signal to the comparator when the dimmer switch is turned off. Further, the comparator compares the charging curve signal and the triangular wave signal to form a PWM signal whose duty cycle is gradually reduced.
  • the LED dimming driving device further includes a switching circuit, and the switching circuit is configured to turn on the RC circuit and the ground when the dimming switch is turned off.
  • the comparator is configured to cause the comparator to receive the charging profile signal.
  • the switch circuit is configured to disconnect the RC circuit from the comparator when the dimmer switch is in communication.
  • the LED dimming drive further includes a feedback circuit for connecting the LED path to the comparator. Further, the RC circuit and the feedback circuit are connected to the same input of the comparator. Further, the feedback circuit is connected when the switching circuit disconnects the RC circuit from the comparator.
  • the RC circuit includes a capacitor, one end of the capacitor being grounded, the other end being connected to the comparator, and a resistor connected in parallel with the capacitor. Additionally, the LED dimming drive further includes a voltage source for charging the capacitor.
  • the LED dimming driving method includes the steps of: when the dimmer switch controls one LED path to block, outputting a charging curve signal to the comparator to generate a PWM signal whose duty cycle is gradually reduced.
  • the present invention when the dimming switch is turned off, the present invention additionally provides a charging curve signal to the comparator to compare with the triangular wave, so that the PWM signal of the control boosting circuit does not immediately become a low level, and The PWM signal with the duty cycle is gradually reduced to continue driving the boosting circuit for several cycles, so that the inductor current in the boosting circuit is slowly decreased, and then the switching transistor in the boosting circuit is turned off. Therefore, the LED dimming driving device and method of the present invention can solve the problem of noise and electromagnetic interference generated when the LED path is extinguished.
  • 1 is a block diagram of a conventional LED dimming drive circuit
  • FIG. 2 is a block diagram of a LED dimming driving device according to a preferred embodiment of the present invention.
  • FIG. 3 is a waveform diagram of a triangular wave signal, a charging curve signal, and a PWM signal according to the embodiment
  • FIG. 5 is a flow chart of a method for driving a dimming LED according to a preferred embodiment of the present invention.
  • FIG. 2 is a block diagram of a LED dimming driving device according to a preferred embodiment of the present invention.
  • the LED dimming drive device 100 of the present embodiment is illustrated only by driving a single LED path 20, and there may actually be multiple LED paths.
  • the LED dimming driving device 100 of the embodiment basically includes a dimming switch 110, a current detector 120, a voltage source 130, a waveform generating circuit 140, a boosting circuit 150, a comparator 160, an RC circuit 170, and a switching circuit 180. And a feedback circuit 190.
  • voltage source 130 provides the power required by boost circuit 150, waveform generation circuit 140, and RC circuit 170, respectively.
  • the boost circuit 150 converts the voltage provided by the voltage source 130 to an appropriate voltage to provide the power required to illuminate the LED path 20.
  • the boosting circuit 150 is electrically connected to the LED path 20 for providing a suitable DC voltage/current of the LED path 20.
  • the dimmer switch 110 is used to control the communication or blocking of one LED path 20 .
  • the current detector 120 is configured to detect a current/voltage flowing through the LED path 20.
  • the current detector 120 is coupled to the comparator 160 through a feedback circuit 190 for providing a voltage signal flowing through the LED path 20 to the Comparator 160.
  • the comparator 160 also receives a triangular wave (or sawtooth wave) generated by the waveform generating circuit 140 for comparison with a voltage signal flowing through the LED path 20.
  • the comparator 160 is further electrically connected to the boosting circuit 150, and the comparator receives a triangular wave signal to generate a PWM signal, and the PWM signal controls the boosting circuit 150 to change the LED path. 20 voltage.
  • FIG. 3 is a waveform diagram of a triangular wave signal, a charging curve signal and a PWM signal according to the embodiment.
  • the RC circuit 170 is electrically connected to the comparator 160.
  • the RC circuit 170 is configured to output a charging curve signal to the comparator 160 when the dimming switch 110 is turned off.
  • the horizontal axis is time
  • the vertical axis is voltage
  • the charging curve signal is represented by C
  • the triangular wave signal is represented by T.
  • the comparator 160 compares the charging curve signal C and the triangular wave signal T to form a duty ratio (Duty Cycle) gradually decreasing PWM signal.
  • the comparator 160 compares the voltage between the charging curve signal C and the triangular wave signal T. When the voltage of the triangular wave signal T is greater than the voltage of the charging curve signal C, the output of the comparator 160 outputs a high level H; When the voltage of the triangular wave signal T is less than the voltage of the charging curve signal C, the output of the comparator 160 outputs a low level L.
  • a charging curve signal C is additionally provided to be compared with the triangular wave signal T, so that the PWM signal controlling the boosting circuit does not immediately become the low level L, but gradually decreases in duty ratio.
  • the reduced PWM signal continues to drive the boost circuit for several cycles, causing the inductor current in boost circuit 150 to slowly drop. Therefore, the LED dimming driving device 100 of the present embodiment can solve the problem of noise and electromagnetic interference generated when the LED path is extinguished.
  • FIG. 4 is a schematic circuit diagram of the LED dimming driving device 100 of the embodiment. It should be noted that, for the sake of clarity, the circuit diagram does not show a complete circuit, which omits some of the electronic components.
  • the switch circuit 180 of the LED dimming driving device 100 of the present embodiment includes a first switch SW1, a second switch SW2, and a third switch SW3.
  • the RC circuit 170 of the present embodiment includes a capacitor C1 having one end grounded, the other end connected to the comparator 160, and a resistor R2 connected in parallel with the capacitor C1.
  • the voltage source 130 is used to charge the capacitor C1.
  • the feedback circuit 190 is configured to connect the LED via 20 to the comparator 160, wherein the RC circuit 170 and the feedback circuit 190 are connected to the same input of the comparator 160.
  • the boost circuit 150 includes a field effect transistor Q, an inductor L, and a diode D. The gate of the field effect transistor Q is electrically connected to the output of the comparator 160, and the field effect transistor Q is used to be turned on or off according to the high and low of the PWM signal.
  • the switch circuit 180 is configured to disconnect the RC circuit 170 from the comparator 160 when the dimmer switch 110 is in communication. Specifically, when the dimmer switch 110 is in the ON state, the first switch SW1 and the second switch SW2 are turned off, the capacitor C1 discharges the resistor R2, and the third switch SW3 is closed. That is, when the switch circuit 110 disconnects the RC circuit 170 from the comparator 160, the feedback circuit 190 is connected. At this time, the LED path 20 is in a normal light-emitting period.
  • the switch circuit 180 is further configured to turn on the RC circuit 170 and the comparator 160 when the dimming switch 110 is turned off, so that the comparator 160 receives the charging curve signal C. .
  • the first switch SW1 and the second switch SW2 are closed, and the third switch SW3 is turned off.
  • one of the comparators 160 detects the voltage value of the capacitor C1, and the voltage source 130 divides the capacitor C1 through the resistor R1, and the voltage of the capacitor C1 (shown in FIG. 3) rises exponentially. And gradually reach a fixed value.
  • the comparator 160 compares the charging curve signal C of the capacitor C1 with the triangular wave signal T, and outputs a PWM signal having a smaller duty cycle as the gate signal of the field effect transistor Q at the output end of the comparator 160, thereby making the stream The current through the inductor L gradually decreases, eventually turning off the field effect transistor Q.
  • FIG. 5 is a flowchart of a method for driving a dimming LED according to a preferred embodiment of the present invention.
  • the LED dimming driving method of the present invention adopts an LED dimming driving device 100, which includes a dimming switch 110, and the dimming switch 110 controls one LED path 20 to communicate or block, and the LED dimming driving device further
  • the booster circuit 150 is electrically connected to the LED path; the comparator 160 is electrically connected to the booster circuit 150, and the comparator 160 receives the triangular wave signal T to generate a PWM signal, and the PWM signal is controlled.
  • the boosting circuit 150 and the RC circuit 170 are electrically connected to the comparator 160, and the RC circuit 170 is configured to output a charging curve signal C to the comparison when the dimming switch 110 is turned off. 160. Please refer to the above for the description of the components mentioned in the method, and will not be repeated here.
  • step S10 when the dimmer switch 110 controls one of the LED paths 20 to communicate, the connection of the RC circuit 170 to the comparator 160 is turned off, so that the LED path 20 starts to emit light.
  • step S20 when the dimmer switch 110 controls the blocking of one of the LED paths 20, the RC circuit 170 and the comparator 160 are turned on, and a charging curve signal C is outputted to the comparator 160 to generate a decreasing duty ratio. PWM signal.
  • the present invention when the dimming switch 110 is turned off, the present invention additionally provides a charging curve signal C to the comparator 160 for comparison with the triangular wave signal T, so that the PWM signal of the control boosting circuit 150 is not immediately Low level L, but the PWM signal with decreasing duty cycle continues to drive the boost circuit 150 for several cycles, so that the inductor L current in the boost circuit 150 slowly drops, and then the field effect in the boost circuit 150 is turned off. Transistor Q. Therefore, the LED dimming driving device and method of the present invention can solve the problem of noise and electromagnetic interference generated when the LED path is extinguished.

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  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Led Devices (AREA)

Abstract

本发明提供了一种LED调光驱动装置及方法，该装置其包括一调光开关，所述调光开关控制一路LED通路连通或阻断。所述装置还包括：升压电路，电性连接于所述LED通路；比较器，电性连接于所述升压电路，所述比较器接收三角波信号以产生PWM信号，所述PWM信号控制所述升压电路；及RC电路，电性连接于所述比较器，所述RC电路用于当所述调光开关断开时，输出一充电曲线信号到所述比较器，以改善升压电路的噪声及电磁干扰。

Description

LED调光驱动装置及方法 技术领域
本发明涉及发光二极管(Light Emitting Diode, LED)技术领域，特别涉及一种LED调光驱动装置及方法。
 背景技术
请参阅图1，图1为现有LED调光驱动电路的方块图。如图所示，驱动原理主要是利用电压源10提供工作电压到一路LED通路 20，所述LED通路20连接有一个开关电路30，并于开关电路30之后串接一电流侦测器40。
其中，电流侦测器40通常为一电阻，利用电流流经电阻所产生的压降来侦测电流量。将电流侦测器40连接至一比较电路50，将电流侦测器40所得之电压与三角波42进行比较，当三角波42之电压大于电流侦测器40所得之电压时，比较电路161输出一高电平信号，反之则输出低电平信号，藉以产生一脉冲宽度调制(Pulse Width Modulation, PWM) 信号52，用以控制开关电路30之连通或阻断。透过改变PWM信号52的占空比，即可控制LED通路20的发光期间，并根据发光期间的长短控制LED通路20的发光亮度。
目前经常会有改变LED发光亮度的调光需求，常用的手段为使用可变电阻为电流侦测器40，通过改变可变电阻的阻值，使相同电流下电流侦测器40所得之电压降低或升高，经过比较电路50即可提高或降低PWM信号52的占空比，进而改变LED通路20的发光亮度。另一种手段为改变三角波42的振幅，在固定电阻值的条件下，亦可改变PWM信号52的占空比，而达到调光的目的。
然而，当开关电路30内的开关管Q2断开的瞬间，以升压(boost)电路实施的电压源10中的场效应晶体管Q1接收的栅极信号GATE为低电平。此时，LED通路20灭掉，使得流过电感L的电流急剧下降，导致电感磁芯振动，产生较大的噪声。同时，电压源10也会产生较大的电磁干扰。
 技术问题
本发明的一个目的在于提供一种LED调光驱动装置，以解决现有技术中，当在LED通路熄灭瞬间，所产生之噪声及电磁干扰的问题。
本发明的另一个目的在于提供一种LED调光驱动方法，以解决当在LED通路熄灭瞬间，所产生之噪声及电磁干扰的问题。
 技术解决方案
本发明的一优选实施例提供了一种LED调光驱动装置，包括一调光开关，所述调光开关控制一路LED通路连通或阻断。所述LED调光驱动装置还包括：升压电路，电性连接于所述LED通路；比较器，电性连接于所述升压电路，所述比较器接收三角波信号以产生PWM信号，所述PWM信号控制所述升压电路；及RC(Resistor Capacitor)电路，电性连接于所述比较器，所述RC电路用于当所述调光开关断开时，输出一充电曲线信号到所述比较器。更进一步来说，所述比较器比较所述充电曲线信号及所述三角波信号以形成占空比逐渐减少的PWM信号。
在本发明优选实施例的LED调光驱动装置中，所述LED调光驱动装置还包括开关电路，所述开关电路用于当所述调光开关断开时，导通所述RC电路与所述比较器，使得所述比较器接收所述充电曲线信号。具体而言，所述开关电路用于当所述调光开关连通时，断开所述RC电路与所述比较器的连接。
在此优选实施例中，所述LED调光驱动装置还包括反馈电路，所述反馈电路用于连接所述LED通路与所述比较器。进一步来说，所述RC电路与所述反馈电路连接至所述比较器的同一输入端。此外，当所述开关电路断开所述RC电路与所述比较器的连接时，连通所述反馈电路。
在本发明优选实施例的LED调光驱动装置中，所述RC电路包括电容，所述电容一端接地，另一端接至所述比较器；及与所述电容并联的电阻。此外，所述LED调光驱动装置还包括电压源，所述电压源用于对所述电容充电。
本发明的另一优选实施例提供了一种LED调光驱动方法。所述LED调光驱动方法包括步骤：当调光开关控制一路LED通路阻断时，输出一充电曲线信号到比较器以产生占空比逐渐减少的PWM信号。
 有益效果
相对于现有技术，本发明在所述调光开关断开时，额外提供给比较器一个充电曲线信号来与三角波做比较，使得控制升压电路的PWM信号并不是马上成为低电平，而是以占空比逐渐减少的PWM信号继续驱动升压电路几个周期，使得升压电路内的电感电流缓慢下降，再关断升压电路内的开关管。因此，本发明的LED调光驱动装置及方法可解决当在LED通路熄灭瞬间，所产生之噪声及电磁干扰的问题。
 附图说明
图1为现有LED调光驱动电路的方块图；
图2为本发明优选实施例的LED调光驱动装置的方块示意图；
图3为本实施例的三角波信号、充电曲线信号及PWM信号波型图；
图4为本实施例的LED调光驱动装置的电路示意图；及
图5为本发明优选实施例的LED调光驱动方法的流程图。
 本发明的最佳实施方式
以下各实施例的说明是参考附加的图式，用以例示本发明可用以实施的特定实施例。
请参阅图2，图2为本发明优选实施例的LED调光驱动装置的方块示意图。为了清楚说明，本实施例的LED调光驱动装置100仅以驱动单一路LED通路20来说明，实际上可能有多路LED通路。本实施例的LED调光驱动装置100基本上包括有调光开关110、电流侦测器120、电压源130、波形产生电路140、升压电路150、比较器160、RC电路170、开关电路180及反馈电路190。
如图2所示，电压源130分别提供升压电路150、波形产生电路140及RC电路170所需之电力。所述升压电路150将电压源130提供的电压转换成适当的电压，以提供给LED通路20发光所需的电力。所述升压电路150电性连接于所述LED通路20，用于提供LED通路20适合的直流电压/电流。
所述调光开关110用于控制一路LED通路20连通或阻断。电流侦测器120用于侦测流经LED通路20的电流/电压，电流侦测器120透过反馈电路190连接至比较器160，用于将流经LED通路20的电压信号提供至所述比较器160。
所述比较器160还接收波形产生电路140所产生的三角波（或称锯齿波），用来与流经LED通路20的电压信号进行比较。此外，所述比较器160还电性连接于所述升压电路150，所述比较器接收三角波信号以产生PWM信号，所述PWM信号控制所述升压电路150，用以改变提供给LED通路20的电压。
请一并参照图2及图3，图3为本实施例的三角波信号、充电曲线信号及PWM信号波型图。如图2所示，RC电路170电性连接于所述比较器160，所述RC电路170用于当所述调光开关110断开时，输出一充电曲线信号到所述比较器160。如图3所示，其中水平轴为时间，垂直轴为电压，充电曲线信号以C表示、三角波信号以T表示。所述比较器160比较所述充电曲线信号C及所述三角波信号T以形成占空比(Duty cycle)逐渐减少的PWM信号。详细来说，比较器160比较充电曲线信号C与三角波信号T之间的电压大小，当三角波信号T的电压大于充电曲线信号C的电压时，比较器160的输出端则输出高电平H；当三角波信号T的电压小于充电曲线信号C的电压时，比较器160的输出端则输出低电平L。
因此，当调光开关110断开时，额外提供一个充电曲线信号C来与三角波信号T做比较，使得控制升压电路的PWM信号并不是马上成为低电平L，而是以占空比逐渐减少的PWM信号继续驱动升压电路几个周期，使得升压电路150内的电感电流缓慢下降。因此，本实施例的LED调光驱动装置100可解决当在LED通路熄灭瞬间，所产生之噪声及电磁干扰的问题。
以下将配合图4来详细说明本实施例LED调光驱动装置100之具体电路。请参照图3及图4，图4为本实施例的LED调光驱动装置100的电路示意图。需注意的是，为了清楚说明，本电路示意图并未绘示出完整电路，其省略了部分电子元件。
如图2及图4所示，本实施例的LED调光驱动装置100的开关电路180包括了第一开关SW1、第二开关SW2及第三开关SW3。另外，本实施例的RC电路170包括电容C1，所述电容C1一端接地，另一端接至所述比较器160；及与所述电容C1并联的电阻R2。此外，所述电压源130用于对所述电容C1充电。所述反馈电路190用于连接所述LED通路20与所述比较器160，其中所述RC电路170与所述反馈电路190连接至所述比较器160的同一输入端。值得一的是，升压电路150包括场效应晶体管Q、电感L及二极管D。所述场效应晶体管Q的栅极电性连接于所述比较器160的输出端，且所述场效应晶体管Q用于根据所述PWM信号的高低导通或关断。
请参阅图4，所述开关电路180用于当所述调光开关110连通时，断开所述RC电路170与所述比较器160的连接。具体来说，当调光开关110为ON状态时，第一开关SW1及第二开关SW2断开，电容C1对电阻R2放电，且第三开关SW3闭合。也就是说，当所述开关电路110断开所述RC电路170与所述比较器160的连接时，连通所述反馈电路190。此时LED通路20处于正常发光期间。
另一方面，所述开关电路180还用于当所述调光开关110断开时，导通所述RC电路170与所述比较器160，使得所述比较器160接收所述充电曲线信号C。
当调光开关110为OFF状态时，第一开关SW1及第二开关SW2闭合，第三开关SW3断开。此时，比较器160之一接收端侦测到电容C1的电压值，而电压源130透过电阻R1分压来对电容C1充电，电容C1的电压（如图3所示）为指数上升，而逐渐到达一固定值。而比较器160将电容C1的充电曲线信号C与三角波信号T比较，而于比较器160的输出端输出占空比越来越小的PWM信号作为场效应晶体管Q的栅极信号，而使得流经电感L的电流逐渐减小，最终关闭场效应晶体管Q。
以下将说明本发明中采用此实施例的LED调光驱动装置100的LED调光驱动方法。请参照图5，图5为本发明优选实施例的LED调光驱动方法的流程图。本发明的LED调光驱动方法采用一种LED调光驱动装置100，其包括一调光开关110，所述调光开关110控制一路LED通路20连通或阻断，所述LED调光驱动装置还包括：升压电路150，电性连接于所述LED通路；比较器160，电性连接于所述升压电路150，所述比较器160接收三角波信号T以产生PWM信号，所述PWM信号控制所述升压电路150；及RC电路170，电性连接于所述比较器160，所述RC电路170用于当所述调光开关110断开时，输出一充电曲线信号C到所述比较器160。方法中所提到的元件说明请参考前述，在此不再予以赘述。
该方法开始于步骤S10。在步骤S10中，当调光开关110控制一路LED通路20连通时，切断RC电路170与所述比较器160的连接，使得LED通路20开始发光。
在步骤S20中，当调光开关110控制一路LED通路20阻断时，导通所述RC电路170与所述比较器160，输出一充电曲线信号C到比较器160以产生占空比逐渐减少的PWM信号。
综上所述，本发明在所述调光开关110断开时，额外提供给比较器160一个充电曲线信号C来与三角波信号T做比较，使得控制升压电路150的PWM信号并不是马上成为低电平L，而是以占空比逐渐减少的PWM信号继续驱动升压电路150几个周期，使得升压电路150内的电感L电流缓慢下降，再关断升压电路150内的场效应晶体管Q。因此，本发明的LED调光驱动装置及方法可解决当在LED通路熄灭瞬间，所产生之噪声及电磁干扰的问题。
虽然本发明已以优选实施例揭露如上，但上述优选实施例并非用以限制本发明，本领域的普通技术人员，在不脱离本发明的精神和范围内，均可作各种更动与润饰，因此本发明的保护范围以权利要求界定的范围为准。
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Claims (15)

  1. 一种LED调光驱动装置，包括一调光开关，所述调光开关控制一路LED通路连通或阻断，所述LED调光驱动装置还包括：
    升压电路，电性连接于所述LED通路；
    比较器，电性连接于所述升压电路，所述比较器接收三角波信号以产生PWM信号，所述PWM信号控制所述升压电路；
    RC电路，电性连接于所述比较器，所述RC电路用于当所述调光开关断开时，输出一充电曲线信号到所述比较器以产生占空比逐渐减少的PWM信号；及
    开关电路，所述开关电路用于当所述调光开关断开时，导通所述RC电路与所述比较器，使得所述比较器接收所述充电曲线信号。
  2. 根据权利要求1所述的LED调光驱动装置，其中所述比较器比较所述充电曲线信号及所述三角波信号以形成占空比逐渐减少的PWM信号。
  3. 根据权利要求1所述的LED调光驱动装置，其中所述开关电路用于当所述调光开关连通时，断开所述RC电路与所述比较器的连接。
  4. 根据权利要求1所述的LED调光驱动装置，其中所述LED调光驱动装置还包括反馈电路，所述反馈电路用于连接所述LED通路与所述比较器。
  5. 根据权利要求4所述的LED调光驱动装置，其中当所述开关电路断开所述RC电路与所述比较器的连接时，连通所述反馈电路。
  6. 一种LED调光驱动装置，包括一调光开关，所述调光开关控制一路LED通路连通或阻断，所述LED调光驱动装置还包括：
    升压电路，电性连接于所述LED通路；
    比较器，电性连接于所述升压电路，所述比较器接收三角波信号以产生PWM信号，所述PWM信号控制所述升压电路；及
    RC电路，电性连接于所述比较器，所述RC电路用于当所述调光开关断开时，输出一充电曲线信号到所述比较器。
  7. 根据权利要求6所述的LED调光驱动装置，其中所述比较器比较所述充电曲线信号及所述三角波信号以形成占空比逐渐减少的PWM信号。
  8. 根据权利要求6所述的LED调光驱动装置，其中所述LED调光驱动装置还包括开关电路，所述开关电路用于当所述调光开关断开时，导通所述RC电路与所述比较器，使得所述比较器接收所述充电曲线信号。
  9. 根据权利要求8所述的LED调光驱动装置，其中所述开关电路用于当所述调光开关连通时，断开所述RC电路与所述比较器的连接。
  10. 根据权利要求8所述的LED调光驱动装置，其中所述LED调光驱动装置还包括反馈电路，所述反馈电路用于连接所述LED通路与所述比较器。
  11. 根据权利要求10所述的LED调光驱动装置，其中所述RC电路与所述反馈电路连接至所述比较器的同一输入端。
  12. 根据权利要求10所述的LED调光驱动装置，其中当所述开关电路断开所述RC电路与所述比较器的连接时，连通所述反馈电路。
  13. 根据权利要求6所述的LED调光驱动装置，其中所述RC电路包括电容，所述电容一端接地，另一端接至所述比较器；及与所述电容并联的电阻。
  14. 根据权利要求13所述的LED调光驱动装置，其中所述LED调光驱动装置还包括电压源，所述电压源用于对所述电容充电。
  15. 一种LED调光驱动方法，包括步骤：
    当调光开关控制一路LED通路阻断时，输出一充电曲线信号到比较器以产生占空比逐渐减少的PWM信号。
PCT/CN2013/070857 2013-01-18 2013-01-22 Led调光驱动装置及方法 Ceased WO2014110840A1 (zh)

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