WO2019024134A1 - 背光驱动电路 - Google Patents

背光驱动电路 Download PDF

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Publication number
WO2019024134A1
WO2019024134A1 PCT/CN2017/097872 CN2017097872W WO2019024134A1 WO 2019024134 A1 WO2019024134 A1 WO 2019024134A1 CN 2017097872 W CN2017097872 W CN 2017097872W WO 2019024134 A1 WO2019024134 A1 WO 2019024134A1
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Prior art keywords
voltage
unit
auxiliary
electrically connected
output
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2017/097872
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English (en)
French (fr)
Inventor
曹丹
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TCL China Star Optoelectronics Technology Co Ltd
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Shenzhen China Star Optoelectronics Technology Co Ltd
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Publication of WO2019024134A1 publication Critical patent/WO2019024134A1/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]
    • H05B45/385—Switched mode power supply [SMPS] using flyback topology
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC
    • H02M5/04—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters
    • H02M5/10—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using transformers
    • H02M5/12—Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into DC by static converters using transformers for conversion of voltage or current amplitude only
    • 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
    • H05B45/395—Linear regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • 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 present invention relates to the field of display technologies, and in particular, to a backlight driving circuit.
  • a conventional liquid crystal display device uses a cold cathode fluorescent lamp (FL) as a backlight.
  • FL cold cathode fluorescent lamp
  • a dedicated backlight drive circuit is required to provide the LED string with its normal illumination driving voltage.
  • FIG. 1 which includes an input unit 110 , a transformer T′, a voltage output unit 120 , a control driving unit 130 , and a constant current driving unit 140 , wherein the input unit 110 is used for power supply access.
  • the transformer T' is electrically connected to the input unit 110, and the output end of the transformer T' is electrically connected to the voltage output unit 120 and the control driving unit 130, respectively, and the voltage output unit 120 is used for backlighting and constant
  • the flow control unit 140 provides a driving voltage
  • the control driving unit 130 is for controlling the output of the voltage output unit 120
  • the constant current driving unit 140 is for controlling a current range flowing on the backlight.
  • the transformer T' comprises a primary winding P', a secondary winding S1' and an auxiliary winding S2', the secondary winding S1' being coupled to the primary winding P', the auxiliary winding S2' coupling the secondary Winding S1'
  • the number of turns of the coil of the primary winding P' / the number of turns of the secondary winding S1' is 1/1
  • the number of turns of the winding S2' is 3/1, that is, the number of turns of the secondary winding S1' is larger than the number of turns of the auxiliary winding S2', so that when the output voltage of the secondary winding S1' is At 30V, the output voltage of the auxiliary winding S2' is 10V.
  • the conventional control drive unit 130 is generally designed to have an output voltage range of the secondary winding S1'.
  • the control for example, controls the output voltage range of the auxiliary winding S2' to be 9V-12V.
  • the control driving unit 130 controls the backlight driving circuit to be turned off, and the voltage output unit 120 of the backlight driving circuit no longer outputs the voltage, thereby the secondary winding.
  • the output voltage range of S1' is 27V-36V.
  • the backlights will generally be different, resulting in different voltages required for the backlight. For example, a backlight with more LED lamps requires a larger voltage, and a backlight with less LED lamps requires a smaller voltage.
  • the control driving unit 130 controls the backlight driving circuit.
  • the output voltage range of the secondary winding S1' of the backlight driving circuit is narrow, so that the output voltage range of the voltage output unit 120 is relatively narrow, and is not suitable for products with large voltage differences or products with large voltage fluctuations.
  • a backlight driving circuit thereby limiting the use of such a backlight driving circuit.
  • the technical problem to be solved by the present invention is to provide a backlight driving circuit.
  • the output voltage range of the voltage output unit of the backlight driving circuit can be expanded.
  • the present invention provides a backlight driving circuit, including:
  • a voltage output unit electrically connected to an output end of the first secondary winding for outputting a backlight driving voltage
  • the transformer further includes a second auxiliary winding unit, the second auxiliary winding unit is coupled to the first secondary winding, and the second auxiliary winding unit is electrically connected to the control driving unit, the first The output voltage of the auxiliary winding is smaller than the output voltage of the second auxiliary winding unit, and the first auxiliary winding and the second auxiliary winding unit are commonly connected to the voltage control terminal of the control driving unit.
  • the second auxiliary winding unit comprises:
  • a second auxiliary secondary winding coupled to the second auxiliary primary winding, the second auxiliary secondary winding being electrically coupled to a voltage control terminal of the control drive unit.
  • the output voltage of the second auxiliary secondary winding is greater than the output voltage of the first auxiliary winding.
  • the number of turns of the second auxiliary primary winding is greater than the number of turns of the first secondary winding.
  • the number of turns of the first secondary winding / the number of turns of the first auxiliary winding is greater than the number of turns of the second auxiliary primary winding / the number of turns of the second auxiliary secondary winding.
  • the backlight driving circuit further includes a constant current driving unit, and the constant current driving unit is electrically connected to an output end of the second auxiliary primary winding and the voltage output unit, respectively.
  • the method further includes a step-down circuit, one end of the step-down circuit is electrically connected to an output end of the second auxiliary primary winding, and the other end of the step-down circuit is electrically connected to the constant current driving unit, the second auxiliary primary winding
  • the output voltage is stepped down by the step-down circuit and output to the constant current drive unit.
  • the voltage output unit and the buck circuit are connected in common to the voltage input end of the constant current driving unit, and the voltage outputted by the buck circuit to the voltage input end of the constant current driving unit is greater than the output of the voltage output unit to the constant current.
  • the voltage at the voltage input of the drive unit is greater than the output of the voltage output unit to the constant current.
  • the step-down circuit comprises a second transistor, a thirty-fifth resistor and a Zener diode, and a collector of the second transistor is electrically connected to an output end of the second auxiliary primary winding,
  • the collector and the base of the two triodes are electrically connected to the thirty-fifth resistor, the base of the second triode is electrically connected to the cathode of the Zener diode, and the anode of the Zener diode is grounded, the The emitter of the two transistors is electrically connected to the constant current drive unit.
  • the method further includes a fifteenth diode, a seventeenth diode, and a capacitor, wherein an anode of the fifteenth diode is electrically connected to the first end of the second auxiliary primary winding, and the capacitor is electrically connected Between the anode of the fifteenth diode and the second end of the second auxiliary primary winding, the anode of the seventeenth diode is electrically connected to the emitter of the second triode, the tenth The cathode of the seven diode is electrically connected to the constant current driving unit.
  • the transformer further includes a second auxiliary winding unit, the second auxiliary winding unit is coupled to the first secondary winding, the second auxiliary winding unit is electrically connected to the control driving unit, and an output voltage of the first auxiliary winding Less than an output voltage of the second auxiliary winding unit, and the first auxiliary winding and the second auxiliary winding unit are commonly connected to a voltage control terminal of the control driving unit; and the voltage control terminal of the control driving unit receives the second auxiliary winding
  • the output voltage of the unit, the lower limit of the output voltage of the first secondary coil can be broadened, so that the lower limit of the output voltage range of the voltage output unit can be broadened, and the requirements of different backlights can be applied, thereby improving the application range of the backlight driving circuit. .
  • FIG. 1 is a circuit diagram of a backlight driving circuit of the prior art
  • FIG. 2 is a circuit diagram of a backlight driving circuit in accordance with an embodiment of the present invention.
  • the present invention provides a backlight driving circuit.
  • an input unit 210, a transformer T, a voltage output unit 220, and a control driving unit 230 are included.
  • the input unit 210 is used for accessing a power source.
  • the input unit 210 can be connected to a power supply circuit of the display device, or directly connected to a power source.
  • the voltage on the power source is input to the backlight driving circuit through the input unit 210.
  • the input unit 210 includes a rectifying and filtering circuit and an RCD absorbing circuit 212.
  • the rectifying and filtering circuit is used for accessing a power source, and the rectifying and filtering circuit includes a bridge rectifying circuit 213 and an LC filter 211.
  • the bridge rectifier circuit 213 is connected by diodes D1-D4 for connecting two input ends of the input unit 210, and two outputs of the LC filter 211 and the bridge rectifier circuit 213.
  • the LC filter 211 includes an inductor L and a first capacitor C1.
  • the inductor L is electrically connected to the first output end of the bridge rectifier circuit 213, and both ends of the first capacitor C1 and the inductor L are The output end is electrically connected to the second output end of the bridge rectifier circuit 213, and one end of the first capacitor C1 electrically connected to the second output end of the bridge rectifier circuit 213 is electrically grounded; the RCD absorption circuit 212 and the rectification An output of the filter circuit is electrically connected, specifically electrically connected to an output of the LC filter 211, the RCD absorbing circuit 212 is configured to filter a sharp wave voltage on the input unit 210, and the RCD absorbing circuit 212 includes a sixth Resistor R6, second capacitor C2, third a capacitor C3, a fourth capacitor C4, and a fifth diode D5, wherein the sixth resistor R6, the second capacitor C2, and the fourth capacitor C4 are both electrically connected to an output end of the LC filter 211, and the sixth
  • One end of the C2 connection is electrically connected to the anode of the fifth diode D5 through a wire to form a second output end of the RCD absorbing circuit 212, and the fourth capacitor C4 is not electrically connected to the output end of the LC filter 211. Ground.
  • the transformer T is electrically connected to the input unit 210. Specifically, the transformer T is electrically connected to an output end of the RCD absorbing circuit 212.
  • the transformer T includes a first primary winding P, a first secondary winding S1, and a first Auxiliary winding S2.
  • the two ends of the first primary winding P are electrically connected to the first output end and the second output end of the RCD absorbing circuit 212, and the first secondary winding S1 is coupled to the first primary winding P.
  • the number of turns of the first secondary winding S1 / the number of turns of the first primary winding P is 1/1
  • the first auxiliary winding S2 is coupled to the first secondary winding S1.
  • the number of turns of the first secondary winding S1 / the first auxiliary winding is 3/1, that is, the number of turns of the first secondary winding S1 is larger than the number of turns of the first auxiliary winding S2.
  • the transformer T further includes a core, and the first primary winding P, the first secondary winding S1, and the first auxiliary winding S2 are wound around the iron core.
  • the voltage output unit 220 is electrically connected to the two output ends of the first secondary winding S1, and the voltage output unit 220 is configured to output a voltage to the backlight, that is, to provide power to the LEDs and the like in the backlight.
  • the voltage output unit 220 includes a rectifier diode D6, a fifth capacitor C5, a sixth capacitor C6, a seventh resistor R7, an eighth resistor R8, and two voltage output terminals.
  • the rectifier diode The anode of D6 is electrically connected to the first output end of the first secondary winding S1, and the two ends of the fifth capacitor C5 are electrically connected to the cathode of the rectifier diode D6 and the second output end of the first secondary winding S1, respectively.
  • the second output end of the first secondary winding S1 is electrically grounded, the eighth resistor R8 is electrically connected to the second output end of the first secondary winding S1, and the seventh resistor is connected in parallel with the eighth resistor R8.
  • One end of the sixth capacitor C6 is electrically connected to the cathode of the rectifier diode D6, and the other end of the sixth capacitor C6 is electrically connected to one end of the eighth resistor that is not grounded, and the two ends of the sixth capacitor C6 are respectively
  • the voltage output terminal is electrically connected; in the embodiment, the rectifier diode D6 is used for rectifying the voltage output by the first secondary winding S1, and the fifth capacitor C5 and the sixth capacitor C6 are opposite to the first secondary winding S1.
  • the output voltage is regulated and filtered, and the voltage is input
  • the output terminal is used to power the backlight.
  • the control driving unit 230 is electrically connected to the first auxiliary winding S2, and the control driving unit 230 controls the voltage output of the voltage output unit 220.
  • the control driving unit 230 is also electrically connected to the input unit 210, and specifically to the output end of the bridge rectifier circuit.
  • the transformer T further includes a second auxiliary winding. a unit, the second auxiliary winding unit is coupled to the first secondary winding S1, and the second auxiliary winding unit is electrically connected to the control driving unit 230, and an output voltage of the first auxiliary winding S2 is smaller than the second auxiliary An output voltage of the winding unit, and the first auxiliary winding S2 and the second auxiliary winding unit are commonly connected to a voltage control terminal of the control driving unit 230.
  • the voltage control terminal of the moving unit 230 since the output voltage of the second auxiliary winding unit is greater than the output voltage of the first auxiliary winding S2, the voltage control terminal of the control driving unit 230 receives the output voltage of the second auxiliary winding unit, thereby
  • the lower limit of the output voltage of a secondary coil can be broadened, so that the lower limit of the output voltage range of the voltage output unit 220 can be broadened, so that the requirements of different backlights can be applied, thereby improving the application range of the backlight driving circuit.
  • the voltage range of the voltage control terminal of the control driving unit 230 is 9-12V
  • the output voltage of the first auxiliary winding S2 is less than 9V
  • the output voltage of the second auxiliary winding unit To be larger than the output voltage of the first auxiliary winding S2, for example, 9.1V
  • the voltage control terminal of the control driving unit 230 recognizes the voltage of 9.1V, and the voltage range is in the range of 9V-12V, so that the control driving unit 230 does not control the backlight driving circuit to be turned off.
  • the output voltage of the first secondary winding S1 can reach 24V, thereby widening the output voltage of the first secondary winding S1 compared to the output voltage of the first secondary winding S1 of the prior art cannot be lower than 27V. Range, after that, the output voltage of the first secondary winding S1 is processed by the voltage output unit 220, and the output voltage range of the voltage output unit 220 is broadened, so that The need for different backlights increases the range of applications for backlight drive circuits.
  • the second auxiliary winding unit includes a second auxiliary primary winding S4 and a second auxiliary secondary winding S3, and the second auxiliary primary winding S4 is coupled with the first secondary winding S1,
  • the second auxiliary secondary winding S3 is coupled to the second auxiliary primary winding S4, and the second auxiliary secondary winding S3 is electrically connected to the voltage control terminal of the control drive unit 230, that is, the second auxiliary secondary winding S3 It is connected in common to the first auxiliary winding S2 to the voltage control terminal of the control driving unit 230.
  • the output voltage on the second auxiliary secondary winding S3 is greater than the output voltage of the first auxiliary winding S2.
  • the number of turns of the second auxiliary primary winding S4 is greater than the first
  • the number of turns of the secondary winding S1 is in the range of 2:1 to 4:1, for example 2:1 3:1, 4:1, the following is an example of 3:1.
  • the number of turns of the coil ⁇ the number of turns of the second auxiliary secondary winding S3 / the number of turns of the second auxiliary primary winding S4, since the number of turns of the second auxiliary primary winding S4 is greater than the first secondary winding S1
  • the number of turns of the coil is such that the output voltage on the second auxiliary secondary winding S3 is greater than the output voltage of the first auxiliary winding S2.
  • the number of turns of the second auxiliary primary winding S4 / the number of turns of the first secondary winding S1 is 3:1
  • the number of turns of the first secondary winding S1 / the first auxiliary winding S2 When the number of turns of the coil is 3:1, that is, the number of turns of the second auxiliary secondary winding S3 / the number of turns of the second auxiliary primary winding S4 is greater than 1:3, for example, the coil of the second auxiliary secondary winding S3
  • the number of turns of the turns/second auxiliary primary winding S4 is 1:1, so that the number of turns of the coil of the first secondary winding S1 / the number of turns of the second auxiliary secondary winding S3 is 1:3, thereby
  • the output voltage of the first secondary winding S1 is 3V
  • the output voltage of the first auxiliary winding S2 is 1V
  • the output voltage of the second auxiliary secondary winding S3 is 9V
  • the output voltage of the first secondary winding S1 can reach 3V, so that the first secondary winding S1
  • the output voltage range can reach a range of 3V-36V, thereby expanding the output voltage range of the voltage output unit 220, and can be applied to different backlight driving circuits.
  • the backlight driving circuit further includes a constant current driving unit 240.
  • the voltage input end of the constant current driving unit 240 is electrically connected to the voltage output unit 220, and the constant current driving unit 240 is used to control the backlight.
  • the upper current range, the voltage output unit 220 output voltage is used for the constant current driving unit 240 to operate.
  • the voltage output from the voltage output unit 220 to the constant current driving unit 240 is also lowered, thereby possibly causing the constant current driving unit 240. Not working.
  • the voltage input terminal of the constant current driving unit 240 is also electrically connected to the output end of the second auxiliary primary winding S4, and the output voltage of the second auxiliary primary winding S4 is used for supplying.
  • the output voltage on the second auxiliary primary winding S4 is greater than the output voltage on the first secondary winding S1.
  • the backlight driving circuit further includes a step-down circuit 250, and the step-down circuit 250 is used for the second The output voltage of the auxiliary primary winding S4 is stepped down, one end of the step-down circuit 250 is electrically connected to the output end of the second auxiliary primary winding S4, and the other end of the step-down circuit 250 is electrically connected to the voltage input terminal of the constant current driving unit 240. Connected, the voltage outputted by the second auxiliary primary winding S4 is stepped down by the buck circuit 250 and output to the constant current driving unit 240.
  • the voltage output from the buck circuit 250 to the voltage input terminal of the constant current driving unit 240 is greater than the voltage output unit. 220 outputs the voltage to the voltage input terminal of the constant current driving unit 240, thereby preventing the constant current driving unit 240 from operating due to the output voltage of the voltage output unit 220 being too low.
  • the step-down circuit 250 includes a second transistor Q2, a resistor R35, and a Zener diode D16.
  • the collector of the second transistor Q2 is electrically connected to the second auxiliary primary winding.
  • An output terminal of S4, a collector R15 of the second transistor Q2 is electrically connected to a resistor R35, and a base of the second transistor Q2 is electrically connected to a cathode of the Zener diode D16.
  • the anode of the diode D16 is grounded, and the emitter of the second transistor Q2 is electrically connected to the constant current driving unit 240.
  • the Zener diode D16 limits the base of the second transistor Q2, for example, the voltage of the base of the second transistor Q2 is limited to 11V, so that the second transistor Q2 emits The output voltage of the pole is limited, so that the voltage of the emitter output of the second transistor Q2 to the constant current driving unit 240 is prevented from being excessively high to damage the constant current driving unit 240.
  • a seventeenth diode D17 is further disposed between the step-down circuit 250 and the constant current driving unit 240, and an anode of the seventeenth diode D17 is electrically connected to the second.
  • the emitter of the transistor Q2, the cathode of the seventeenth diode D17 is electrically connected to the constant current driving unit 240, and the seventeenth diode D17 is used for rectification.
  • the second transistor Q2 is an npn-type second triode.
  • the backlight driving circuit further includes a fifteenth diode D15 and a seventeenth capacitor C17, and the fifteenth diode D15 and the seventeenth capacitor C17 are located in the second auxiliary primary winding.
  • the anode of the fifteenth diode D15 is electrically connected to the first output of the second auxiliary primary winding S4
  • the The second output end of the second auxiliary primary winding S4 is electrically grounded, and the two ends of the seventeenth capacitor C17 are respectively electrically connected to the cathode of the fifteenth diode D15 and the second output end of the second auxiliary primary winding S4.
  • the fifteenth diode D15 is used to rectify the output voltage of the second auxiliary primary winding S4, which is used to regulate and filter the output voltage of the second auxiliary primary winding S4.
  • the constant current driving unit 240 includes a first operational amplifier OP1 and a second operational amplifier OP2.
  • the backlight driving circuit further includes an optocoupler U, the optocoupler U illuminator is electrically connected to the constant current driving unit 240, and the first end of the photocoupler of the optocoupler U passes through the thirteenth resistor R13 and the ninth
  • the resistor R9 is electrically connected to the control driving unit 230, and an output end of the thirteenth resistor is electrically connected to one port of the control driving unit 230, and an output end of the ninth resistor R9 and the control driving unit Another port of 230 is electrically connected, and the ninth resistor R9 is connected in parallel with the series branch formed by the seventh capacitor C5 and the tenth resistor R10, and the output end of the thirteenth resistor R13 is further connected to the eleventh resistor R11.
  • the second end of the photoreceptor of the optocoupler U is electrically connected to the second end of the photocoupler of the optocoup
  • the backlight driving circuit further includes a first resistor R1 - a fifth resistor R5, a twelfth resistor R12, a fourteenth resistor R14 - a twentieth resistor R20, and a twenty-second resistor R22-
  • the first output end of the bridge rectifier circuit 213 is electrically grounded via a first resistor R1, a second resistor R2, and a twelfth resistor R12, wherein the output of the second resistor is
  • the control driving unit 230 is electrically connected, and the twelfth resistor R12 is connected in parallel with the eighth capacitor C8.
  • the third output R3, the fourth resistor R4 and the third resistor are further disposed between the first output end of the bridge rectifier circuit 213 and the inductor L.
  • a fifth resistor R5 the third resistor R3 and the fourth resistor R4 are connected in series, and two ends are electrically connected to the first output end of the bridge rectifier circuit 213 and the base of the first transistor Q1, respectively, the fifth resistor
  • the two ends of the R5 are electrically connected to the first output end of the bridge rectifier circuit 213 and the collector of the first transistor Q1, respectively.
  • the collector of the first electrically grounded transistor Q1, the emitter of the first transistor Q1 and the control driving unit 230 are electrically connected.
  • the second output end of the RCD absorbing circuit 212 is electrically connected to the source of the MOS transistor Q3, the drain of the MOS transistor Q3 is electrically grounded via the seventeenth resistor R17, and the drain of the MOS transistor Q3 is also via the tenth
  • the fourth resistor R14 and the ninth capacitor C9 are electrically grounded.
  • the output end of the fourteenth resistor R14 is also electrically connected to the port of the control driving unit 230, and the grounded end of the ninth capacitor C9 is electrically connected to the other port of the control driving unit 230.
  • the gate of the MOS transistor Q3 is electrically connected to the drain of the MOS transistor Q3 via the sixteenth resistor R16, and the gate of the MOS transistor Q3 is via the The fifteen resistor R15 is electrically connected to the control driving unit 230.
  • the second ends of the first auxiliary winding S2 and the second auxiliary secondary winding S3 are electrically grounded, and the first end of the first auxiliary winding S2 is via the nineteenth resistor R19, the ninth diode D9,
  • the eighth diode D8 is electrically connected to the control driving unit 230.
  • the first end of the eighth diode D8 electrically connected to the control driving unit 230 is electrically connected to the first end of the tenth capacitor C10 and the eleventh capacitor C11, respectively.
  • the tenth capacitor C10 and the second end of the eleventh capacitor C11 are electrically grounded, and the line between the ninth diode D9 and the eighth diode D8 is electrically connected to the line via the twelfth capacitor C12.
  • the first end of the winding S3 is electrically connected to the output of the nineteenth resistor R19 via the eighteenth resistor R18.
  • the first voltage output terminal of the two voltage output terminals of the voltage output unit 220 is electrically connected via the thirty-second resistor R32, the thirty-third resistor R33, and the thirty-fourth resistor R34 connected in series. Grounding, and the first voltage output terminal is electrically grounded via the eleventh diode D11, the twenty-fourth resistor R24, and the twelfth diode D12 connected in series, and the two voltage outputs of the voltage output unit 220 The second voltage output terminal in the terminal is connected through the thirty-first resistor in series
  • the sixteenth capacitor C16 is electrically grounded.
  • the cathode of the eleventh diode D11 is electrically connected to the cathode of the seventeenth diode D17, and the cathode of the eleventh diode D11 is further connected to the twenty-fifth resistor R25 and the twenty-second
  • the resistor R22 is electrically connected to the first end of the illuminator of the optocoupler U, the output end of the twenty-fifth resistor R25 is electrically connected to the constant current driving unit 240, and the output end of the twenty-fifth resistor R25 And electrically connected to the thirteenth diode D10 and the thirteenth capacitor C13 in parallel; and the output end of the twenty-fourth resistor R24 is electrically connected to the twenty-eighth resistor R28, the twenty-eighth resistor The output end of the R28 is electrically connected to the 29th resistor R29 and the 30th resistor R30 in parallel.
  • the output ends of the 29th resistor R29 and the 30th resistor R30 are electrically grounded, and the light of the optocoupler U is emitted.
  • the second end of the device is electrically connected to the output end of the first operational amplifier OP1 via the thirteenth diode D13, and is electrically connected to the output end of the second operational amplifier OP2 via the fourteenth diode D14.
  • the first end of the illuminator of U is electrically connected to the second end of the illuminator via the twenty-third resistor R23, and, third The output end of the three resistor R33 is electrically connected to the inverting input terminal of the second operational amplifier OP2, and the output end of the second operational amplifier OP2 is electrically connected to the second operational amplifier via the fifteenth capacitor C15 and the twenty-seventh resistor R27 connected in series.
  • An output end of the third eleventh resistor R31 is electrically connected to an inverting input end of the first operational amplifier OP1, the first operational amplifier
  • the output end of the OP1 is electrically connected to the inverting input terminal of the first operational amplifier OP1 via the fourteenth capacitor C14 and the twenty-sixth resistor R26 connected in series, and the input end of the twenty-eighth resistor R28 and the second operational amplifier
  • the non-inverting input terminal of the OP2 is electrically connected, and the output end of the twenty-eighth resistor R28 is electrically connected to the non-inverting input terminal of the first operational amplifier OP1.
  • the constant current driving unit 240 is electrically grounded.
  • the present invention has the following advantages:
  • the transformer further includes a second auxiliary winding unit
  • the second auxiliary winding unit is coupled to the first secondary winding
  • the second auxiliary winding unit is electrically connected to the control driving unit
  • an output voltage of the first auxiliary winding Less than an output voltage of the second auxiliary winding unit
  • the first auxiliary winding and the second auxiliary winding unit are commonly connected to a voltage control terminal of the control driving unit.
  • the voltage control terminal of the control driving unit receives the output voltage of the second auxiliary winding unit, so that the lower limit of the output voltage of the first secondary coil can be broadened, so that the lower limit of the output voltage range of the voltage output unit can be broadened, thereby being applicable.
  • the need for different backlights has increased the range of applications for backlight drive circuits.

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Abstract

一种背光驱动电路，包括：输入单元(210)；变压器(T)，其包括：第一初级绕组(P)，其与输入单元(210)的输出端电连接；第一次级绕组(S1)，其与第一初级绕组(P)耦合；第一辅助绕组(S2)，其与第一次级绕组(S1)耦合；电压输出单元(220)；控制驱动单元(230)；其中，变压器(T)还包括第二辅助绕组单元，第二辅助绕组单元与第一次级绕组(S1)耦合，第二辅助绕组单元与控制驱动单元(230)电连接，第一辅助绕组(S2)的输出电压小于第二辅助绕组单元的输出电压，且第一辅助绕组(S2)与第二辅助绕组单元共同连接到控制驱动单元(230)的电压控制端。背光驱动电路具有可扩大电压输出单元(220)的输出电压范围的优点。

Description

背光驱动电路
本发明要求2017年8月2日递交的发明名称为“背光驱动电路”的申请号CN201710651630.9的在先申请优先权，上述在先申请的内容以引入的方式并入本文本中。
技术领域
本发明涉及显示技术领域，特别是涉及一种背光驱动电路。
背景技术
随着技术的不断进步，液晶显示装置的背光技术不断得到发展。传统的液晶显示装置的背光源采用冷阴极荧光灯(FL)。但是由于FL背光源存在色彩还原能力较差、发光效率低、放电电压高、低温下放电特性差、加热达到稳定灰度时间长等缺点，当前已经开发出使用LED背光源的背光源技术。
在LED背光源中，需要通过专门的背光驱动电路来为LED串提供其正常发光的驱动电压。现有的背光驱动电路请参见图1，其包括输入单元110、变压器T’、电压输出单元120、控制驱动单元130、恒流驱动单元140，其中，所述输入单元110用于电源的接入，所述变压器T’与所述输入单元110电连接，所述变压器T’的输出端分别与电压输出单元120、控制驱动单元130电连接，所述电压输出单元120用于给背光源和恒流控制单元140提供驱动电压，所述控制驱动单元130用于控制电压输出单元120的输出，所述恒流驱动单元140用于控制所述背光源上流过的电流范围。
其中，所述变压器T’包括初级绕组P’、次级绕组S1’和辅助绕组S2’，所述次级绕组S1’耦合所述初级绕组P’，所述辅助绕组S2’耦合所述次级绕组S1’，在本实施例中，所述初级绕组P’的线圈匝数/次级绕组S1’的线圈匝数为1/1，所述次级绕组S1’的线圈匝数/所述辅助绕组S2’的线圈匝数为3/1，也即所述次级绕组S1’的线圈匝数多于所述辅助绕组S2’的线圈匝数，从而，当次级绕组S1’的输出电压为30V时，辅助绕组S2’的输出电压为10V。一般说来，现有的所述控制驱动单元130一般在设计时会对次级绕组S1’的输出电压范围进行 控制，例如控制辅助绕组S2’的输出电压范围为9V-12V，当低于9V时控制驱动单元130则控制背光驱动电路关闭，背光驱动电路的电压输出单元120不再输出电压，从而次级绕组S1’的输出电压范围为27V-36V。然而，由于不同产品的要求，背光源一般也会不同，导致背光源所需的电压也会不同，例如LED灯多的背光源需要的电压较大，LED灯少的背光源需要的电压较小，从而，当次级绕组S1’的输出电压低于27V时，此时辅助绕组S2’的输出电压低于9V，不在9V-12V的电压范围内，此时控制驱动单元130控制背光驱动电路不工作，导致此种背光驱动电路的次级绕组S1’的输出电压范围较窄，从而电压输出单元120的输出电压范围比较窄，不适合电压差异较大的产品或者电压波动较大的产品共用该种背光驱动电路，从而限制了该种背光驱动电路的使用。
发明内容
本发明所要解决的技术问题在于，提供一种背光驱动电路。可扩大背光驱动电路的电压输出单元的输出电压范围。
为了解决上述技术问题，本发明提供了一种背光驱动电路，包括：
输入单元，其用于电源的接入；
变压器，其包括：
第一初级绕组，其与所述输入单元的输出端电连接；
第一次级绕组，其与所述第一初级绕组耦合；
第一辅助绕组，其与所述第一次级绕组耦合；
电压输出单元，其与所述第一次级绕组的输出端电连接，其用于输出背光驱动电压；
控制驱动单元，其与所述第一辅助绕组电连接；
其中，所述变压器还包括第二辅助绕组单元，所述第二辅助绕组单元与所述第一次级绕组耦合，所述第二辅助绕组单元与所述控制驱动单元电连接，所述第一辅助绕组的输出电压小于所述第二辅助绕组单元的输出电压，且所述第一辅助绕组与所述第二辅助绕组单元共同连接到所述控制驱动单元的电压控制端。
其中，所述第二辅助绕组单元包括：
第二辅助初级绕组，其与所述第一次级绕组耦合；
第二辅助次级绕组，其与所述第二辅助初级绕组耦合，所述第二辅助次级绕组与所述控制驱动单元的电压控制端电连接。
其中，所述第二辅助次级绕组的输出电压大于所述第一辅助绕组的输出电压。
其中，所述第二辅助初级绕组的线圈匝数大于所述第一次级绕组的线圈匝数。
其中，所述第一次级绕组的线圈匝数/所述第一辅助绕组的线圈匝数大于所述第二辅助初级绕组的线圈匝数/所述第二辅助次级绕组的线圈匝数。
其中，所述背光驱动电路还包括恒流驱动单元，所述恒流驱动单元分别与所述第二辅助初级绕组的输出端、所述电压输出单元电连接。
其中，还包括降压电路，所述降压电路一端与所述第二辅助初级绕组的输出端电连接，所述降压电路另一端与恒流驱动单元电连接，所述第二辅助初级绕组输出的电压经由降压电路降压后输出给恒流驱动单元。
其中，所述电压输出单元和所述降压电路共同连接到恒流驱动单元的电压输入端，所述降压电路输出给恒流驱动单元电压输入端的电压大于所述电压输出单元输出给恒流驱动单元电压输入端的电压。
其中，所述降压电路包括第二三极管、第三十五电阻和稳压二极管，所述第二三极管的集电极电连接所述第二辅助初级绕组的输出端，所述第二三极管的集电极和基极之间电连接第三十五电阻，所述第二三极管的基极电连接稳压二极管的阴极，所述稳压二极管的阳极接地，所述第二三极管的发射极电连接恒流驱动单元。
其中，还包括第十五二极管、第十七二极管和电容，所述第十五二极管的阳极电连接所述第二辅助初级绕组的第一端，所述电容电连接在所述第十五二极管的阳极与所述第二辅助初级绕组的第二端之间，所述第十七二极管的阳极电连接第二三极管的发射极，所述第十七二极管的阴极电连接恒流驱动单元。
实施本发明，具有如下有益效果：
由于所述变压器还包括第二辅助绕组单元，所述第二辅助绕组单元与第一次级绕组耦合，所述第二辅助绕组单元与控制驱动单元电连接，所述第一辅助绕组的输出电压小于所述第二辅助绕组单元的输出电压，且所述第一辅助绕组与所述第二辅助绕组单元共同连接到控制驱动单元的电压控制端；控制驱动单元的电压控制端接收第二辅助绕组单元的输出电压，第一次级线圈的输出电压的下限可以得到拓宽，从而电压输出单元的输出电压范围的下限可以得到拓宽，可以适用不同的背光源的需求，提升了背光驱动电路的应用范围。
附图说明
为了更清楚地说明本发明或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是现有技术一种背光驱动电路的电路图；
图2是本发明一实施例背光驱动电路的电路图。
具体实施方式
下面将结合本发明中的附图，对本发明中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本申请说明书、权利要求书和附图中出现的术语“包括”和“具有”以及它们任何变形，意图在于覆盖不排他的包含。例如包含了一系列步骤或单元的过程、方法、系统、产品或设备没有限定于已列出的步骤或单元，而是可选地还包括没有列出的步骤或单元，或可选地还包括对于这些过程、方法、产品或设备固有的其它步骤或单元。此外，术语“第一”、“第二”和“第三”等是用于区别不同的对象，而并非用于描述特定的顺序。
本发明提供一种背光驱动电路，请参见图2，包括输入单元210、变压器T、电压输出单元220和控制驱动单元230。
所述输入单元210用于电源的接入，所述输入单元210可以接显示装置的电源电路，也可以直接接电源，电源上的电压通过输入单元210输入到背光驱动电路中。在本实施例中，所述输入单元210包括整流滤波电路和RCD吸收电路212，所述整流滤波电路用于电源的接入，所述整流滤波电路包括桥式整流电路213和LC滤波器211，具体说来，所述桥式整流电路213由二极管D1-D4连接而成，用于连接所述输入单元210的两个输入端，所述LC滤波器211与桥式整流电路213的两个输出端电连接，所述LC滤波器211包括电感L和第一电容C1，所述电感L与桥式整流电路213的第一输出端电连接，所述第一电容C1的两端与电感L的输出端和桥式整流电路213的第二输出端电连接，且所述第一电容C1与桥式整流电路213的第二输出端电连接的一端电性接地；所述RCD吸收电路212与整流滤波电路的输出端电连接，具体与所述LC滤波器211的输出端电连接，所述RCD吸收电路212用于滤掉输入单元210上的尖波电压，所述RCD吸收电路212包括第六电阻R6、第二电容C2、第三电容C3、第四电容C4和第五二极管D5，其中，所述第六电阻R6、第二电容C2和第四电容C4均与LC滤波器211的输出端电连接，且第六电阻R6、第二电容C2和第四电容C4共同的一端形成RCD吸收电路212的第一输出端，所述第五二极管D5的阴极与第六电阻R6串联，所述第三电容C3与第二电容C2串联，且第三电容C3与第二电容C2之间的线路与第六电阻R6和第五二极管D5之间的线路通过导线电连接，所述第三电容C3非与第二电容C2连接的一端与第五二极管D5的阳极通过导线电连接以形成RCD吸收电路212的第二输出端，所述第四电容C4不与LC滤波器211的输出端电连接的一端电性接地。
所述变压器T与输入单元210电连接，具体说来，所述变压器T与RCD吸收电路212的输出端电连接，所述变压器T包括第一初级绕组P、第一次级绕组S1、第一辅助绕组S2。其中，所述第一初级绕组P的两端与RCD吸收电路212的第一输出端、第二输出端对应电连接，所述第一次级绕组S1与所述第一初级绕组P耦合，在本实施例中，所述第一次级绕组S1的线圈匝数/第一初级绕组P的线圈匝数为1/1，所述第一辅助绕组S2与所述第一次级绕组S1耦合，在本实施例中，第一次级绕组S1的线圈匝数/所述第一辅助绕组 S2的线圈匝数为3/1，也即第一次级绕组S1的线圈匝数多于第一辅助绕组S2的线圈匝数。例如，当第一初级绕组P上的输出电压为30V时，第一次级绕组S1上的输出电压也为30V，第一辅助绕组S2上的输出电压为10V。在本实施例中，所述变压器T还包括铁芯，所述第一初级绕组P、第一次级绕组S1、第一辅助绕组S2绕在铁芯上。
所述电压输出单元220与第一次级绕组S1的两输出端电连接，所述电压输出单元220用于输出电压给背光源，也即提供电源给背光源内的LED灯等发光元器件。在本实施例中，所述电压输出单元220包括整流二极管D6、第五电容C5、第六电容C6、第七电阻R7、第八电阻R8和两电压输出端子，具体说来，所述整流二极管D6的阳极与第一次级绕组S1的第一输出端电连接，所述第五电容C5的两端分别与整流二极管D6的阴极、第一次级绕组S1的第二输出端电连接，所述第一次级绕组S1的第二输出端电性接地，所述第八电阻R8与所述第一次级绕组S1的第二输出端电连接，所述第七电阻与第八电阻R8并联，所述第六电容C6的一端与整流二极管D6的阴极电连接，所述第六电容C6的另一端与第八电阻不接地的一端电连接，所述第六电容C6的两端分别与两电压输出端子电连接；在本实施例中，所述整流二极管D6用于对第一次级绕组S1输出的电压进行整流，所述第五电容C5、第六电容C6对第一次级绕组S1输出的电压进行稳压和滤波，所述电压输出端子用于给背光源供电。
所述控制驱动单元230与第一辅助绕组S2电连接，所述控制驱动单元230控制电压输出单元220的电压输出。在本实施例中，所述控制驱动单元230还与输入单元210电连接，具体与桥式整流电路的输出端电连接。
为了使电压输出单元220的输出电压范围比较宽，本实施例中通过增大输出电压的下限来拓宽输出电压范围，具体说来，在本实施例中，所述变压器T还包括第二辅助绕组单元，所述第二辅助绕组单元与第一次级绕组S1耦合，且所述第二辅助绕组单元与控制驱动单元230电连接，所述第一辅助绕组S2的输出电压小于所述第二辅助绕组单元的输出电压，且所述第一辅助绕组S2与所述第二辅助绕组单元共同连接到控制驱动单元230的电压控制端。从而，当第一辅助绕组S2的输出电压和第二辅助绕组单元的电压共同传输给控制驱 动单元230的电压控制端时，由于第二辅助绕组单元的输出电压要大于第一辅助绕组S2的输出电压，从而控制驱动单元230的电压控制端接收第二辅助绕组单元的输出电压，从而第一次级线圈的输出电压的下限可以得到拓宽，从而电压输出单元220的输出电压范围的下限可以得到拓宽，从而可以适用不同的背光源的需求，从而提升了背光驱动电路的应用范围。
举例说来，当控制驱动单元230电压控制端的电压范围为9-12V时，当第一辅助绕组S2的输出电压小于9V时，假定为8V，此时，所述第二辅助绕组单元的输出电压要大于第一辅助绕组S2的输出电压，例如为9.1V，此时，由于第二辅助绕组单元的输出电压9.1V大于第一辅助绕组S2的输出电压8V，从而当控制驱动单元230的电压控制端同时接受9.1V和8V的电压时，控制驱动单元230的电压控制端会识别9.1V的电压，此时电压范围在9V-12V的范围内，从而控制驱动单元230不会控制背光驱动电路关闭，此时，第一次级绕组S1的输出电压可以达到24V，从而，相比现有技术的第一次级绕组S1的输出电压不能低于27V，拓宽了第一次级绕组S1的输出电压范围，此后，第一次级绕组S1的输出电压经过电压输出单元220处理后进行输出，同样，电压输出单元220的输出电压范围得到了拓宽，从而可以适用不同的背光源的需求，从而提升了背光驱动电路的应用范围。
在本实施例中，所述第二辅助绕组单元包括第二辅助初级绕组S4和第二辅助次级绕组S3，所述第二辅助初级绕组S4与所述第一次级绕组S1耦合，所述第二辅助次级绕组S3与所述第二辅助初级绕组S4耦合，所述第二辅助次级绕组S3与所述控制驱动单元230的电压控制端电连接，也即第二辅助次级绕组S3与第一辅助绕组S2共同连接到控制驱动单元230的电压控制端。在本实施例中，当第一次级绕组S1的输出电压确定后，所述第二辅助次级绕组S3上的输出电压大于所述第一辅助绕组S2的输出电压。
为了实现所述第二辅助次级绕组S3上的输出电压大于所述第一辅助绕组S2的输出电压，在本实施例中，所述第二辅助初级绕组S4的线圈匝数大于所述第一次级绕组S1的线圈匝数，例如，所述第二辅助初级绕组S4的线圈匝数/第一次级绕组S1的线圈匝数的范围为2:1-4:1，例如为2:1、3:1、4:1，下面以3:1为例进行说明。在本实施例中，所述第一次级绕组S1的线圈匝数/第一辅 助绕组S2的线圈匝数＞第二辅助初级绕组S4的线圈匝数/第二辅助次级绕组S3的线圈匝数，也即，第一辅助绕组S2的线圈匝数/第一次级绕组S1的线圈匝数＜第二辅助次级绕组S3的线圈匝数/第二辅助初级绕组S4的线圈匝数，由于所述第二辅助初级绕组S4的线圈匝数大于所述第一次级绕组S1的线圈匝数，从而，述第二辅助次级绕组S3上的输出电压大于所述第一辅助绕组S2的输出电压。
举例说明，当所述第二辅助初级绕组S4的线圈匝数/第一次级绕组S1的线圈匝数为3:1，第一次级绕组S1的线圈匝数/所述第一辅助绕组S2的线圈匝数为3:1时，也即第二辅助次级绕组S3的线圈匝数/第二辅助初级绕组S4的线圈匝数要大于1:3，例如第二辅助次级绕组S3的线圈匝数/第二辅助初级绕组S4的线圈匝数为1:1，从而，第一次级绕组S1的线圈匝数/第二辅助次级绕组S3的线圈匝数为1:3，从而，当第一次级绕组S1的输出电压为3V时，此时，所述第一辅助绕组S2的输出电压为1V，第二辅助次级绕组S3的输出电压为9V，从而当控制驱动单元230的电压控制端同时接受9V和1V的电压时，控制驱动单元230的电压控制端会识别9V的电压，此时电压范围在9V-12V的范围内，从而控制驱动单元230不会控制背光驱动电路关闭，此时，第一次级绕组S1的输出电压可以达到3V，从而第一次级绕组S1的输出电压范围可以达到3V-36V的范围，从而拓展了电压输出单元220的输出电压范围，可以适用不同背光驱动电路的需要。
在本实施例中，所述背光驱动电路还包括恒流驱动单元240，所述恒流驱动单元240的电压输入端与电压输出单元220电连接，所述恒流驱动单元240用于控制背光源上的电流范围，所述电压输出单元220输出电压用于供恒流驱动单元240工作。在本实施例中，由于第一次级绕组S1的输出电压的下限可以得到降低，从而导致电压输出单元220输出给恒流驱动单元240的电压也得到了降低，从而可能导致恒流驱动单元240不工作。为了改善该问题，在本实施例中，所述恒流驱动单元240的电压输入端还与第二辅助初级绕组S4的输出端电连接，所述第二辅助初级绕组S4的输出电压用于供应给恒流驱动单元240，在本实施例中，所述第二辅助初级绕组S4上的输出电压大于所述第一次级绕组S1上的输出电压。
为了防止第二辅助初级绕组S4输出的电压过高而损坏恒流驱动单元240，在本实施例中，所述背光驱动电路还包括降压电路250，所述降压电路250用于对第二辅助初级绕组S4的输出电压进行降压，所述降压电路250一端与第二辅助初级绕组S4的输出端电连接，所述降压电路250另一端与恒流驱动单元240的电压输入端电连接，所述第二辅助初级绕组S4输出的电压经由降压电路250降压后输出给恒流驱动单元240，所述降压电路250输出给恒流驱动单元240电压输入端的电压大于电压输出单元220输出给恒流驱动单元240电压输入端的电压，从而可以防止恒流驱动单元240由于电压输出单元220输出电压过低而不工作。
具体说来，在本实施例中，所述降压电路250包括第二三极管Q2、电阻R35和稳压二极管D16，所述第二三极管Q2的集电极电连接第二辅助初级绕组S4的输出端，所述第二三极管Q2的集电极和基极之间电连接电阻R35，所述第二三极管Q2的基极电连接稳压二极管D16的阴极，所述稳压二极管D16的阳极接地，所述第二三极管Q2的发射极电连接恒流驱动单元240。在本实施例中，由于稳压二极管D16对第二三极管Q2的基极进行了限压，例如限制第二三极管Q2的基极的电压为11V，从而第二三极管Q2发射极的输出电压得到了限制，从而可以防止第二三极管Q2发射极输出给恒流驱动单元240的电压过高而损坏恒流驱动单元240。另外，在本实施例中，所述降压电路250与所述恒流驱动单元240之间还设有第十七二极管D17，所述第十七二极管D17的阳极电连接第二三极管Q2的发射极，所述第十七二极管D17的阴极电连接所述恒流驱动单元240，所述第十七二极管D17用于整流作用。在本实施例中，所述第二三极管Q2为npn型第二三极管。
在本实施例中，所述背光驱动电路还包括第十五二极管D15和第十七电容C17，所述第十五二极管D15和第十七电容C17位于所述第二辅助初级绕组S4的输出端和降压电路250的输入端之间，具体说来，所述第十五二极管D15的阳极与所述第二辅助初级绕组S4的第一输出端电连接，所述第二辅助初级绕组S4的第二输出端电性接地，所述第十七电容C17的两端分别与第十五二极管D15的阴极和所述第二辅助初级绕组S4的第二输出端电连接，且所述第十五二极管D15的阴极与第二三极管Q2的集电极，所述第十五二极管 D15用于对第二辅助初级绕组S4的输出电压进行整流，所述第十七电容C17用于对第二辅助初级绕组S4的输出电压进行稳压和滤波。
另外，在本实施例中，所述恒流驱动单元240包括第一运算放大器OP1和第二运算放大器OP2。所述背光驱动电路还包括光耦U，所述光耦U发光器与所述恒流驱动单元240电连接，所述光耦U的受光器的第一端通过第十三电阻R13、第九电阻R9与所述控制驱动单元230电连接，且所述第十三电阻的输出端与所述控制驱动单元230的一个端口电连接，所述第九电阻R9的输出端与所述控制驱动单元230的另一个端口电连接，而且，所述第九电阻R9与第七电容C5、第十电阻R10形成的串联支路并联，所述第十三电阻R13的输出端还经由第十一电阻R11与所述光耦U的受光器的第二端电连接，所述光耦U的受光器的第二端通过第二十一电阻R21电性接地。
另外，在本实施例中，所述背光驱动电路还包括第一电阻R1-第五电阻R5、第十二电阻R12、第十四电阻R14-第二十电阻R20、第二十二电阻R22-第三十四电阻R34、第八电容C8-第十六电容C16、第七二极管D7-第十五二极管D15、第一三极管Q1、MOS管Q3等元器件，具体连接关系如下，请继续参见图2，所述桥式整流电路213的第一输出端经由第一电阻R1、第二电阻R2、第十二电阻R12电性接地，其中所述第二电阻的输出端与控制驱动单元230电连接，第十二电阻R12与第八电容C8并联；所述桥式整流电路213的第一输出端与电感L之间还设有第三电阻R3、第四电阻R4和第五电阻R5，所述第三电阻R3、第四电阻R4串联且两端分别电连接所述桥式整流电路213的第一输出端和第一三极管Q1的基极，所述第五电阻R5的两端分别电连接所述桥式整流电路213的第一输出端和第一三极管Q1的集电极，其中所述第一三极管Q1的集电极电性接地，所述第一三极管Q1的发射极与控制驱动单元230电连接。所述RCD吸收电路212的第二输出端电连接MOS管Q3的源极，所述MOS管Q3的漏极经由第十七电阻R17电性接地，所述MOS管Q3的漏极还经由第十四电阻R14、第九电容C9电性接地，其中第十四电阻R14的输出端还与控制驱动单元230的端口电连接，第九电容C9接地的一端与控制驱动单元230的另一端口电连接，而且，所述MOS管Q3的栅极经由第十六电阻R16与所述MOS管Q3的漏极电连接，所述MOS管Q3的栅极经由第 十五电阻R15与控制驱动单元230电连接。所述第一辅助绕组S2和所述第二辅助次级绕组S3的第二端电性接地，所述第一辅助绕组S2的第一端经由第十九电阻R19、第九二极管D9、第八二极管D8与控制驱动单元230电连接，所述第八二极管D8与控制驱动单元230电连接的一端还分别电连接第十电容C10、第十一电容C11的第一端，所述第十电容C10、第十一电容C11的第二端电性接地，所述第九二极管D9、第八二极管D8之间的线路经由第十二电容C12电连接到所述第十电容C10、第十一电容C11的第二端；而且，所述第一辅助绕组S2的第一端还经由第二十电阻R20与控制驱动单元230电连接，所述第二辅助次级绕组S3的第一端经由第十八电阻R18与第十九电阻R19的输出端电连接。在本实施例中，所述电压输出单元220的两电压输出端子中的第一电压输出端子经由串联的第三十二电阻R32、第三十三电阻R33、第三十四电阻R34后电性接地，而且，第一电压输出端子还经由串联的第十一二极管D11、第二十四电阻R24、第十二二极管D12后电性接地，所述电压输出单元220的两电压输出端子中的第二电压输出端子经由串联的第三十一电阻
R31、第十六电容C16后电性接地。其中，所述第十一二极管D11的阴极与第十七二极管D17的阴极电连接，所述第十一二极管D11的阴极还经由第二十五电阻R25、第二十二电阻R22与所述光耦U的发光器的第一端电连接，所述第二十五电阻R25的输出端与恒流驱动单元240电连接，且所述第二十五电阻R25的输出端分别经由并联的第十二极管D10、第十三电容C13电性接地；又，所述第二十四电阻R24的输出端与第二十八电阻R28电连接，所述第二十八电阻R28的输出端与并联的第二十九电阻R29、第三十电阻R30电连接，所述第二十九电阻R29、第三十电阻R30的输出端电性接地，所述光耦U的发光器的第二端分别经由第十三二极管D13与第一运算放大器OP1的输出端电连接、经由第十四二极管D14与第二运算放大器OP2的输出端电连接，所述光耦U的发光器的第一端经由第二十三电阻R23与发光器的第二端电连接，而且，第三十三电阻R33的输出端与第二运算放大器OP2的反向输入端电连接，第二运算放大器OP2的输出端经由串联的第十五电容C15、第二十七电阻R27电连接到第二运算放大器OP2的反向输入端，所述第三十一电阻R31的输出端与第一运算放大器OP1的反向输入端电连接，所述第一运算放 大器OP1的输出端经由串联的第十四电容C14、第二十六电阻R26电连接第一运算放大器OP1的反向输入端，而且，第二十八电阻R28的输入端与第二运算放大器OP2的同向输入端电连接，第二十八电阻R28的输出端与第一运算放大器OP1的同向输入端电连接。再者，恒流驱动单元240电性接地。
需要说明的是，本说明书中的各个实施例均采用递进的方式描述，每个实施例重点说明的都是与其它实施例的不同之处，各个实施例之间相同相似的部分互相参见即可。对于装置实施例而言，由于其与方法实施例基本相似，所以描述的比较简单，相关之处参见方法实施例的部分说明即可。
通过上述实施例的描述，本发明具有以下优点：
由于所述变压器还包括第二辅助绕组单元，所述第二辅助绕组单元与第一次级绕组耦合，所述第二辅助绕组单元与控制驱动单元电连接，所述第一辅助绕组的输出电压小于所述第二辅助绕组单元的输出电压，且所述第一辅助绕组与所述第二辅助绕组单元共同连接到控制驱动单元的电压控制端。从而控制驱动单元的电压控制端接收第二辅助绕组单元的输出电压，从而第一次级线圈的输出电压的下限可以得到拓宽，从而电压输出单元的输出电压范围的下限可以得到拓宽，从而可以适用不同的背光源的需求，从而提升了背光驱动电路的应用范围。
以上所揭露的仅为本发明较佳实施例而已，当然不能以此来限定本发明之权利范围，因此依本发明权利要求所作的等同变化，仍属本发明所涵盖的范围。

Claims (20)

  1. 一种背光驱动电路，其中，包括：
    输入单元，其用于电源的接入；
    变压器，其包括：
    第一初级绕组，其与所述输入单元的输出端电连接；
    第一次级绕组，其与所述第一初级绕组耦合；
    第一辅助绕组，其与所述第一次级绕组耦合；
    电压输出单元，其与所述第一次级绕组的输出端电连接，其用于输出背光驱动电压；
    控制驱动单元，其与所述第一辅助绕组电连接；
    其中，所述变压器还包括第二辅助绕组单元，所述第二辅助绕组单元与所述第一次级绕组耦合，所述第二辅助绕组单元与所述控制驱动单元电连接，所述第一辅助绕组的输出电压小于所述第二辅助绕组单元的输出电压，且所述第一辅助绕组与所述第二辅助绕组单元共同连接到所述控制驱动单元的电压控制端。
  2. 如权利要求1所述的背光驱动电路，其中，所述第二辅助绕组单元包括：
    第二辅助初级绕组，其与所述第一次级绕组耦合；
    第二辅助次级绕组，其与所述第二辅助初级绕组耦合，所述第二辅助次级绕组与所述控制驱动单元的电压控制端电连接。
  3. 如权利要求2所述的背光驱动电路，其中，所述第二辅助次级绕组的输出电压大于所述第一辅助绕组的输出电压。
  4. 如权利要求3所述的背光驱动电路，其中，所述第二辅助初级绕组的线圈匝数大于所述第一次级绕组的线圈匝数。
  5. 如权利要求4所述的背光驱动电路，其中，所述第一次级绕组的线圈匝数/所述第一辅助绕组的线圈匝数大于所述第二辅助初级绕组的线圈匝数/所述第二辅助次级绕组的线圈匝数。
  6. 如权利要求2所述的背光驱动电路，其中，所述背光驱动电路还包括恒流驱动单元，所述恒流驱动单元分别与所述第二辅助初级绕组的输出端、所述电压输出单元电连接。
  7. 如权利要求3所述的背光驱动电路，其中，所述背光驱动电路还包括恒流驱动单元，所述恒流驱动单元分别与所述第二辅助初级绕组的输出端、所述电压输出单元电连接。
  8. 如权利要求4所述的背光驱动电路，其中，所述背光驱动电路还包括恒流驱动单元，所述恒流驱动单元分别与所述第二辅助初级绕组的输出端、所述电压输出单元电连接。
  9. 如权利要求5所述的背光驱动电路，其中，所述背光驱动电路还包括恒流驱动单元，所述恒流驱动单元分别与所述第二辅助初级绕组的输出端、所述电压输出单元电连接。
  10. 如权利要求6所述的背光驱动电路，其中，还包括降压电路，所述降压电路一端与所述第二辅助初级绕组的输出端电连接，所述降压电路另一端与恒流驱动单元电连接，所述第二辅助初级绕组输出的电压经由降压电路降压后输出给恒流驱动单元。
  11. 如权利要求7所述的背光驱动电路，其中，还包括降压电路，所述降压电路一端与所述第二辅助初级绕组的输出端电连接，所述降压电路另一端与恒流驱动单元电连接，所述第二辅助初级绕组输出的电压经由降压电路降压后输出给恒流驱动单元。
  12. 如权利要求8所述的背光驱动电路，其中，还包括降压电路，所述降压电路一端与所述第二辅助初级绕组的输出端电连接，所述降压电路另一端与恒流驱动单元电连接，所述第二辅助初级绕组输出的电压经由降压电路降压后输出给恒流驱动单元。
  13. 如权利要求9所述的背光驱动电路，其中，还包括降压电路，所述降压电路一端与所述第二辅助初级绕组的输出端电连接，所述降压电路另一端与恒流驱动单元电连接，所述第二辅助初级绕组输出的电压经由降压电路降压后输出给恒流驱动单元。
  14. 如权利要求10所述的背光驱动电路，其中，所述电压输出单元和所述降压电路共同连接到恒流驱动单元的电压输入端，所述降压电路输出给恒流驱动单元电压输入端的电压大于所述电压输出单元输出给恒流驱动单元电压输入端的电压。
  15. 如权利要求11所述的背光驱动电路，其中，所述电压输出单元和所述降压电路共同连接到恒流驱动单元的电压输入端，所述降压电路输出给恒流驱动单元电压输入端的电压大于所述电压输出单元输出给恒流驱动单元电压输入端的电压。
  16. 如权利要求12所述的背光驱动电路，其中，所述电压输出单元和所述降压电路共同连接到恒流驱动单元的电压输入端，所述降压电路输出给恒流驱动单元电压输入端的电压大于所述电压输出单元输出给恒流驱动单元电压输入端的电压。
  17. 如权利要求13所述的背光驱动电路，其中，所述电压输出单元和所述降压电路共同连接到恒流驱动单元的电压输入端，所述降压电路输出给恒流驱动单元电压输入端的电压大于所述电压输出单元输出给恒流驱动单元电压 输入端的电压。
  18. 如权利要求10所述的背光驱动电路，其中，所述降压电路包括第二三极管、第三十五电阻和稳压二极管，所述第二三极管的集电极电连接所述第二辅助初级绕组的输出端，所述第二三极管的集电极和基极之间电连接所述第三十五电阻，所述第二三极管的基极电连接稳压二极管的阴极，所述稳压二极管的阳极接地，所述第二三极管的发射极电连接恒流驱动单元。
  19. 如权利要求11所述的背光驱动电路，其中，所述降压电路包括第二三极管、第三十五电阻和稳压二极管，所述第二三极管的集电极电连接所述第二辅助初级绕组的输出端，所述第二三极管的集电极和基极之间电连接所述第三十五电阻，所述第二三极管的基极电连接稳压二极管的阴极，所述稳压二极管的阳极接地，所述第二三极管的发射极电连接恒流驱动单元。
  20. 如权利要求18所述的背光驱动电路，其中，还包括第十五二极管、第十七二极管和电容，所述第十五二极管的阳极电连接所述第二辅助初级绕组的第一端，所述电容电连接在所述第十五二极管的阳极与所述第二辅助初级绕组的第二端之间，所述第十七二极管的阳极电连接第二三极管的发射极，所述第十七二极管的阴极电连接恒流驱动单元。
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