WO2018149020A1 - 一种背光驱动电路及液晶显示器 - Google Patents

一种背光驱动电路及液晶显示器 Download PDF

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Publication number
WO2018149020A1
WO2018149020A1 PCT/CN2017/078634 CN2017078634W WO2018149020A1 WO 2018149020 A1 WO2018149020 A1 WO 2018149020A1 CN 2017078634 W CN2017078634 W CN 2017078634W WO 2018149020 A1 WO2018149020 A1 WO 2018149020A1
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Prior art keywords
diode
resistor
switch
capacitor
cathode
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PCT/CN2017/078634
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English (en)
French (fr)
Inventor
李文东
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深圳市华星光电技术有限公司
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Priority to US15/535,447 priority Critical patent/US10311803B2/en
Publication of WO2018149020A1 publication Critical patent/WO2018149020A1/zh

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    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133612—Electrical details
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/064—Adjustment of display parameters for control of overall brightness by time modulation of the brightness of the illumination source
    • 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
    • G09G3/36—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 using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3648—Control of matrices with row and column drivers using an active matrix

Definitions

  • the present invention relates to the field of display technologies, and in particular, to a backlight driving circuit and a liquid crystal display.
  • the backlight power supply circuit for driving large-sized products such as televisions is complicated.
  • the boosting of the LED, the driving switch tube will be short-circuited, usually adopting the method of transformer primary over-power protection in the backlight driving circuit, and the PWM integrated chip is restarted after a period of time.
  • the temperature of the surface of the driving switch tube is too high, thereby failing to meet the safety standards of safety regulations.
  • Another object of the present invention is to provide a liquid crystal display.
  • the invention provides a backlight driving circuit, which is applied to a liquid crystal display, wherein the backlight driving circuit comprises a voltage conversion circuit, a PWM controller, a Zener diode, a first electrical switch, an optocoupler unit, a boost switch and a light source driving component.
  • the voltage conversion circuit is configured to connect an input voltage terminal to receive an input voltage, and perform voltage conversion on the input voltage, the voltage conversion circuit is further connected to the optocoupler unit, the PWM controller, the boost switch, and the liquid crystal a light source of the display to output the converted voltage to the optocoupler unit, the PWM controller, the boost switch, and a light source, the PWM controller for controlling an output of the voltage conversion circuit, the light source driving component Connecting to the boost switch and the light source to control on and off of the boost switch according to a light source condition, a cathode connection of the Zener diode Connecting to the optocoupler unit, an anode of the Zener diode is connected to a control end of the first electric switch, and a first end of the first electric switch is connected to the PWM controller, the first electric The second end of the switch is grounded.
  • the boost switch When the boost switch is short-circuited, the current output by the voltage conversion circuit increases, and the voltage that the optocoupler unit feeds back to the Zener diode is greater than the breakdown voltage, and the Zener diode leads And the first electrical switch is turned on, and the PWM controller stops working to turn off the boost switch.
  • the voltage conversion circuit includes a transformer, a second electrical switch, a first resistor, a first capacitor, a first diode, a second diode, and a second resistor, and the input voltage terminal is connected to the transformer a first end of the first primary coil and connected to the cathode of the first diode through the first resistor, the first capacitor being connected in parallel across the first resistor, the first diode An anode of the tube is connected to the first end of the second electrical switch, an anode of the first diode is further connected to a second end of the first primary coil of the transformer, and a control end of the second electrical switch Connected to the PWM controller, the second end of the second electrical switch is grounded, the first end of the second primary coil of the transformer is connected to the anode of the second diode, the second diode a cathode of the tube is connected to a voltage terminal of the PWM controller through the second resistor, a voltage terminal of the PWM controller is connected to a first end of
  • the light source driving component includes a third electrical switch, a control unit, and a third resistor, a control end of the third electrical switch is connected to the control unit, and a first end of the third electrical switch is connected to the a light source, the second end of the third electrical switch is grounded through the third resistor, and the control unit is further connected to the boost switch to control the boost switch according to a voltage condition of the third resistor On and off.
  • the photocoupler unit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a voltage regulator, and an optocoupler, wherein the fourth resistor and the fifth resistor are connected in series to the secondary of the transformer.
  • the second end of the voltage regulator is grounded, and the sixth resistor and the seventh resistor are connected between the secondary coil of the transformer and the ground, a reference end of the voltage regulator is coupled to a node between the sixth resistor and the seventh resistor, an anode of the light-emitting diode of the optocoupler being coupled to a node between the fourth resistor and the fifth resistor a cathode of the optocoupler light emitting diode is connected to a node between the fifth resistor and the voltage regulator, and a first end of the optocoupler switch is connected to the PWM controller and the voltage regulator A cathode of the diode, the second end of the switch of the optocoupler being grounded.
  • the voltage conversion circuit further includes a third diode, a fourth diode, and the second capacitor, an anode of the third diode is connected to an anode of the fourth diode, and is connected To the transformer a first end of the secondary coil, a cathode of the third diode is connected to an anode of the fourth diode, and is connected to a positive pole of the second capacitor, and a cathode of the second capacitor is grounded The second end of the secondary winding of the transformer is grounded.
  • the voltage conversion circuit further includes a third capacitor and a fourth capacitor, a cathode of the third capacitor is connected to the input voltage terminal, a cathode of the third capacitor is grounded, and the fourth capacitor is connected in parallel Both ends of the third capacitor.
  • the backlight driving circuit further includes a fifth capacitor and a sixth capacitor, wherein a cathode of the fifth capacitor is connected to a cathode of the second diode through the second resistor, and a cathode of the fifth capacitor is grounded.
  • the anode of the sixth capacitor is connected to the cathode of the third diode, and the cathode of the sixth capacitor is grounded.
  • the backlight driving circuit further includes a fifth diode, a storage inductor and a seventh capacitor, wherein an anode of the fifth diode is connected to the third diode and the fourth through the energy storage inductor a cathode of the diode, a cathode of the fifth diode being coupled to an anode of the light source, a cathode of the light source being coupled to a first end of the third electrical switch, a cathode of the fifth diode Also connected to the anode of the seventh capacitor, the cathode of the seventh capacitor being grounded.
  • the boost switch, the second electrical switch, and the third electrical switch are all NPN transistors, and the control terminals of the boost switch, the second electrical switch, and the third electrical switch,
  • the first end and the second end are respectively a gate, a drain and a source
  • the first electric switch is an NPN type triode
  • the control end, the first end and the second end of the first electric switch are respectively bases , collector and emitter.
  • the present invention also provides a liquid crystal display comprising a light source and the above-described backlight driving circuit, the backlight driving circuit being connected to the light source.
  • a backlight driving circuit of the invention comprises a voltage conversion circuit, a PWM controller, a Zener diode, a first electrical switch, an optocoupler unit, a boost switch and a light source driving component, wherein the voltage conversion circuit is used for connecting an input voltage terminal Receiving an input voltage and performing voltage conversion on the input voltage, the voltage conversion circuit is further connected to the optocoupler unit, the PWM controller, the boost switch, and a light source of the liquid crystal display to output the converted voltage Giving the optocoupler unit, the PWM controller, the boost switch, and the light source, the PWM controller for controlling an output of the voltage conversion circuit, the light source driving component being coupled to the boost switch and the light source Controlling the on/off of the boost switch according to a light source condition, a cathode of the Zener diode is connected to the optocoupler unit, and the Zener of the Zener diode a pole connected to the control end of the first electrical switch, a first end of the first electrical switch is connected to the PWM controller
  • FIG. 1 is a circuit diagram of a backlight driving circuit with an overcurrent protection function according to a first embodiment of the present invention
  • FIG. 2 is a block diagram of a liquid crystal display according to a second embodiment of the present invention.
  • ground connection or integral connection; can be mechanical connection; can be directly connected or through The intermediate medium is indirectly connected and can be internal to the two components.
  • the specific meaning of the above terms in the present invention can be understood in a specific case by those skilled in the art.
  • a first embodiment of the present invention provides a backlight driving circuit 100 .
  • the backlight driving circuit 100 is applied to a liquid crystal display to drive a light source of the liquid crystal display to emit light, and also has an overcurrent protection function.
  • the backlight driving circuit 100 includes a voltage conversion circuit 10, a PWM controller 20, a Zener diode Z1, a first electrical switch Q1, an optocoupler unit 40, a boost switch Qr, and a light source driving component 30.
  • the input voltage terminal Vin is connected to receive an input voltage, and the input voltage is voltage-converted.
  • the voltage conversion circuit 10 is further connected to the optocoupler unit 40, the PWM controller 20, the boost switch Qr, and the liquid crystal display.
  • the light source driving component 30 is connected to the boosting switch Qr and the light source to control on and off of the boosting switch Qr according to a light source condition, and a cathode of the Zener diode Z1 is connected to the optocoupler unit 40.
  • the anode of the Zener diode Z1 is connected to the control end of the first electrical switch Q1, and the first end of the first electrical switch Q1 is connected to the PWM controller 20, the first electrical switch Q1 The second end is grounded.
  • the boosting switch Qr When the boosting switch Qr is short-circuited, the current output by the voltage conversion circuit 10 increases, and the voltage fed back to the Zener diode Z1 by the optocoupler unit 40 is greater than the breakdown voltage, and the Zener diode Z1 leads Then, the first electrical switch Q1 is turned on, and the PWM controller 20 stops working to turn off the boost switch Qr.
  • the PWM controller 20 includes a voltage terminal, an output terminal, a detection terminal, and a feedback terminal.
  • the voltage terminal of the PWM controller 20 is connected to the voltage conversion circuit 10 to receive an operating voltage.
  • the voltage terminal of the PWM controller 20 is also coupled to the first end of the first electrical switch Q1.
  • An output of the PWM controller 20 is coupled to the voltage conversion circuit 10 to control an output of the voltage conversion circuit 10.
  • the detection end of the PWM controller 20 is connected to the voltage conversion circuit 10, When it is detected that the voltage output from the voltage conversion circuit 10 to the detection terminal is greater than a preset value, it indicates that an abnormality has occurred, and the PWM controller stops operating.
  • a feedback end of the PWM controller 20 is coupled to the optocoupler unit to receive a feedback voltage of the optocoupler unit 40.
  • the light sources are light-emitting diodes connected in series.
  • the anode of the light emitting diode is the anode of the light source.
  • the cathode of the light emitting diode is the cathode of the light source.
  • the voltage conversion circuit 10 performs voltage conversion on the input voltage to supply a voltage to the light source to cause the light source to emit light.
  • the short circuit of the boosting switch Qr refers to a short circuit between the gate and the drain of the boosting switch Qr.
  • the voltage of the optocoupler unit 40 fed back to the feedback end of the PWC controller 20 is increased.
  • the voltage at the feedback terminal of the PWM controller 20 is greater than the breakdown voltage of the Zener diode Z1.
  • the Zener diode Z1 is broken down, and the first electrical switch Q1 is turned on.
  • the voltage terminal of the PWM controller 20 is grounded.
  • the PWM controller 20 stops working, so that the voltage conversion circuit 10 stops outputting, the boosting switch Qr is turned off, and the surface temperature of the boosting switch Qr is lowered, which not only satisfies the safety standard of the safety regulation, but also realizes Overcurrent protection.
  • the voltage conversion circuit 10 includes a transformer T, a second electrical switch Q2, a first resistor R1, a first capacitor C1, a first diode D1, a second diode D2, and a second resistor R2.
  • An input voltage terminal Vin is connected to a first end of the first primary winding of the transformer T, and is connected to a cathode of the first diode D1 through the first resistor R1, the first capacitor C1 being connected in parallel
  • the two ends of the first resistor R1 are connected to the first end of the second electric switch Q2, and the anode of the first diode D1 is further connected to the transformer T a second end of the first primary coil, a control end of the second electrical switch Q2 is coupled to the PWM controller 20, a second end of the second electrical switch Q2 is grounded, and a second primary of the transformer T a first end of the coil is connected to an anode of the second diode D2, and a cathode of the second diode D2 is connected to a voltage
  • the first resistor R1, the first capacitor C1, and the first diode D1 constitute an RCD absorbing unit.
  • the RCD absorption unit is configured to absorb a voltage spike of the second electrical switch Q2 to prevent the second electrical switch Q2 from being damaged.
  • the second diode D2 and the first The two resistor R2 constitutes a rectifying unit for rectifying the voltage signal of the voltage terminal of the PWM controller 20 with an input value.
  • the voltage conversion circuit 10 further includes an eighth resistor R8.
  • the second end of the second electrical switch Q2 is grounded through the eighth resistor R8.
  • the voltage detected by the detecting end of the PWM controller 20 is the voltage on the eighth resistor R8.
  • the light source driving component 30 includes a third electrical switch Q3, a control unit 32, and a third resistor R3.
  • the control end of the third electrical switch Q3 is connected to the control unit 32, and the first of the third electrical switch Q3 An end is connected to the light source, a second end of the third electrical switch Q3 is grounded through the third resistor R3, and the control unit 32 is further connected to the boost switch Qr according to the third resistor R3
  • the voltage condition controls the on and off of the boost switch Qr.
  • control unit 32 includes a first output end, a second output end, and a detection end.
  • the first output of the control unit 32 is connected to the control end of the third electrical switch Q3.
  • the second output of the control unit 32 is connected to the control terminal of the boost switch Qr.
  • the detecting end of the control unit 32 is connected to the second end of the boost switch Qr.
  • the control unit 32 controls the duty ratio of the PWM signal outputted by the first output terminal to the control terminal of the third electrical switch Q3 by detecting a current flowing through the third resistor R3 to maintain the light source. The current is constant.
  • the second output of the control unit 32 is configured to output a PWM signal to the boost switch Qr to control the on and off of the boost switch Qr.
  • the control unit 32 is further configured to detect a voltage outputted by the second end of the boost switch Qr to the control unit 32. When the voltage is greater than a preset voltage, indicating that an abnormality occurs, the control unit 32 stops operating.
  • the backlight driving circuit further includes a ninth resistor R9.
  • the second end of the boost switch Qr is also grounded through the ninth resistor R9.
  • the voltage outputted to the control unit 32 by the second end of the boost switch Qr is the voltage on the ninth resistor R9.
  • the optocoupler unit 40 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a voltage regulator Z2, and an optocoupler U.
  • the fourth resistor R4 and the fifth resistor R5 are connected in series.
  • the second end of the voltage regulator Z2 is grounded, and the sixth resistor R6 and the seventh resistor R7 are connected to Between the secondary coil of the transformer T and the ground, the reference end of the voltage regulator Z2 is connected to the sixth resistor a node between R6 and the seventh resistor R7, an anode of the light emitting diode of the optocoupler U is connected to a node between the fourth resistor R4 and the fifth resistor R5, and the light of the optocoupler U a cathode of the diode is connected to a node between the fifth resistor R5 and the voltage regulator Z2, and a first end of the switch of the optocoupler U is connected to the PWM controller 20 and the Zener diode Z1 The cathode, the second end of the switch of the optocoupler U is grounded.
  • the reference terminal of the voltage regulator Z2 provides a reference voltage.
  • the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 are voltage dividing resistors.
  • the voltage conversion circuit 10 further includes a third diode D3, a fourth diode D4, and the second capacitor C2, and an anode of the third diode D3 is connected to the fourth diode D4.
  • the anode of the second capacitor C2 is grounded, and the second end of the secondary coil of the transformer T is grounded.
  • the third diode D3 and the fourth diode D4 together constitute a rectifier to rectify the voltage output by the transformer T.
  • the second capacitor C2 functions to store energy.
  • the voltage conversion circuit 10 further includes a third capacitor C3 and a fourth capacitor C4, the anode of the third capacitor C3 is connected to the input voltage terminal Vin, and the cathode of the third capacitor C3 is grounded.
  • the fourth capacitor C4 is connected in parallel at both ends of the third capacitor C3.
  • the third capacitor C3 functions to store energy.
  • the fourth capacitor C4 functions as a high frequency filter.
  • the backlight driving circuit 100 further includes a fifth capacitor C5 and a sixth capacitor C6, and a cathode of the fifth capacitor C5 is connected to a cathode of the second diode D2 through the second resistor R2, the fifth The cathode of the capacitor C5 is grounded, the anode of the sixth capacitor C6 is connected to the cathode of the third diode D3, and the cathode of the sixth capacitor C6 is grounded.
  • the functions of the fifth capacitor C5 and the sixth capacitor C6 are all energy storage.
  • the backlight driving circuit 100 further includes a fifth diode D5, a storage inductor L and a seventh capacitor C7, and an anode of the fifth diode D5 is connected to the third diode through the energy storage inductor L a cathode of the third diode D5, a cathode of the fifth diode D5 is connected to an anode of the light source, and a cathode of the light source is connected to a first end of the third electrical switch Q3 Fifth diode D5 The cathode is also connected to the anode of the seventh capacitor C7, and the cathode of the seventh capacitor C7 is grounded.
  • the fifth diode D5 functions to prevent current from flowing back.
  • the seventh capacitor C7 functions to store energy.
  • the boosting switch Qr, the second electrical switch Q2, and the third electrical switch Q3 are all NPN transistors, the boosting switch Qr, the second electrical switch Q2, and the The control end, the first end and the second end of the third electric switch Q3 are respectively a gate, a drain and a source, and the first electric switch Q1 is an NPN type triode, and the control end of the first electric switch Q1 The first end and the second end are respectively a base, a collector and an emitter.
  • the boost switch Qr, the second electrical switch Q2, and the third electrical switch Q3 may also be other types of transistors.
  • a second embodiment of the present invention provides a liquid crystal display 200.
  • the liquid crystal display 200 includes a light source 210 and a backlight driving circuit connected to the light source 210.
  • the backlight driving circuit may be the backlight driving circuit 100 in the first embodiment. Since the specific structure of the backlight driving circuit 100 has been described in detail in the above first embodiment, it will not be described herein.
  • the liquid crystal display includes the backlight driving circuit 100.
  • the backlight driving circuit 100 includes a voltage conversion circuit 10, a PWM controller 20, a Zener diode Z1, a first electrical switch Q1, an optocoupler unit 40, a boost switch Qr, and a light source driving component 30.
  • the input voltage terminal Vin is connected to receive an input voltage, and the input voltage is voltage-converted.
  • the voltage conversion circuit 10 is further connected to the optocoupler unit 40, the PWM controller 20, the boost switch Qr, and the liquid crystal display.
  • the light source driving component 30 is connected to the boosting switch Qr and the light source to control on and off of the boosting switch Qr according to a light source condition, and a cathode of the Zener diode Z1 is connected to the optocoupler unit 40.
  • the anode of the Zener diode Z1 is connected to the control end of the first electrical switch Q1, and the first end of the first electrical switch Q1 is connected to the PWM controller 20, the first electrical switch Q1 The second end is grounded.
  • the boosting switch Qr When the boosting switch Qr is short-circuited, the current output by the voltage conversion circuit 10 increases, and the voltage fed back to the Zener diode Z1 by the optocoupler unit 40 is greater than the breakdown voltage, and the Zener diode Z1 leads And the first electrical switch Q1 is turned on, and the PWM controller 20 stops working to turn off the boosting switch Qr. Therefore, the surface temperature of the boosting switch Qr is lowered, which not only meets safety standards of safety regulations. It also implements overcurrent protection.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Computer Hardware Design (AREA)
  • Theoretical Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mathematical Physics (AREA)
  • Optics & Photonics (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

一种背光驱动电路（100）及液晶显示器。背光驱动电路（100）包括电压转换电路（10）、PWM控制器（20）、稳压二极管（Z1）、第一电开关（Q1）、光耦单元（40）、升压开关（Qr）及光源驱动组件（30）。电压转换电路（10）为光耦单元（40）、PWM控制器（20）、升压开关（Qr）及光源提供电压；PWM控制器（20）用于控制电压转换电路（10）的输出；光源驱动组件（30）连接至升压开关（Qr）及光源，以根据光源状况控制升压开关（Qr）的通断；稳压二极管（Z1）的阴极连接至光耦单元（40），稳压二极管（Z1）的阳极连接至第一电开关（Q1）的控制端；第一电开关（Q1）的第一端连接至PWM控制器（20），第二端接地。当升压开关（Qr）短路时，电压转换电路（10）输出的电流增大，光耦单元（40）反馈的电压击穿稳压二极管（Z1）来导通第一电开关（Q1），PWM控制器（20）停止工作来截止升压开关（Qr），从而降低了升压开关（Qr）的表面温度，满足了安全标准。

Description

一种背光驱动电路及液晶显示器
本发明要求2017年2月20日递交的发明名称为“一种背光驱动电路及液晶显示器”的申请号2017100899938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
本发明涉及一种显示技术领域，尤其是涉及一种背光驱动电路及液晶显示器。
背景技术
现在的面板设计中，大尺寸产品所占的比重逐渐增大。在驱动大尺寸产品如电视的背光电源电路比较复杂。其中，在现有的电视背光驱动电路中，发光二极管的升压，驱动开关管会发生短路现象，通常在背光驱动电路中采用变压器初级过功率保护的方法，PWM集成芯片隔一段时间进行重启，从而导致驱动开关管表面的温度过高，从而不满足安规的安全标准。
发明内容
本发明的目的在于提供一种背光驱动电路，以降低驱动开关管的温度，来满足安规的安全标准。
本发明的另一目的在于提供一种液晶显示器。
为了实现上述目的，本发明实施方式提供如下技术方案：
本发明提供一种背光驱动电路，应用于液晶显示器中，所述背光驱动电路包括电压转换电路、PWM控制器、稳压二极管、第一电开关、光耦单元、升压开关及光源驱动组件，所述电压转换电路用于连接输入电压端，以接收输入电压，并对输入电压进行电压转换，所述电压转换电路还连接至所述光耦单元、PWM控制器、所述升压开关及液晶显示器的光源，以将转换后的电压输出给所述光耦单元、PWM控制器、所述升压开关及光源，所述PWM控制器用于控制所述电压转换电路的输出，所述光源驱动组件连接至所述升压开关及所述光源，以根据光源状况来控制所述升压开关的通断，所述稳压二极管的阴极连 接至所述光耦单元，所述稳压二极管的阳极连接至所述第一电开关的控制端，所述第一电开关的第一端连接至所述PWM控制器，所述第一电开关的第二端接地，当所述升压开关短路时，所述电压转换电路输出的电流增大，所述光耦单元反馈到稳压二极管的电压大于击穿电压，所述稳压二极管导通，进而所述第一电开关导通，所述PWM控制器停止工作以截止所述升压开关。
其中，所述电压转换电路包括变压器、第二电开关、第一电阻、第一电容、第一二极管、第二二极管及第二电阻，所述输入电压端连接至所述变压器的第一初级线圈的第一端，并通过所述第一电阻连接至所述第一二极管的阴极，所述第一电容并联在所述第一电阻的两端，所述第一二极管的阳极连接至所述第二电开关的第一端，所述第一二极管的阳极还连接至所述变压器的第一初级线圈的第二端，所述第二电开关的控制端连接至所述PWM控制器，所述第二电开关的第二端接地，所述变压器的第二初级线圈的第一端连接至所述第二二极管的阳极，所述第二二极管的阴极通过所述第二电阻连接至所述PWM控制器的电压端，所述PWM控制器的电压端连接至所述第一电开关的第一端，所述变压器的次级线圈连接至所述升压开关的第一端。
其中，所述光源驱动组件包括第三电开关、控制单元及第三电阻，所述第三电开关的控制端连接至所述控制单元，所述第三电开关的第一端连接至所述光源，所述第三电开关的第二端通过所述第三电阻接地，所述控制单元还连接至所述升压开关，以根据所述第三电阻的电压情况控制所述升压开关的通断。
其中，所述光耦单元包括第四电阻、第五电阻、第六电阻、第七电阻、电压调整器及光耦，所述第四电阻及所述第五电阻串联在所述变压器的次级线圈与电压调整器的第一端之间，所述电压调整器的第二端接地，所述第六电阻及所述第七电阻连接至所述变压器的次级线圈与地之间，所述电压调整器的基准端连接至所述第六电阻与所述第七电阻之间的节点，所述光耦的发光二极管的阳极连接至所述第四电阻与所述第五电阻之间的节点，所述光耦的发光二极管的阴极连接至所述第五电阻与所述电压调整器之间的节点，所述光耦的开关的第一端连接至所述PWM控制器及所述稳压二极管的阴极，所述光耦的开关的第二端接地。
其中，所述电压转换电路还包括第三二极管、第四二极管及所述第二电容，所述第三二极管的阳极连接至所述第四二极管的阳极，并连接至所述变压器的 次级线圈的第一端，所述第三二极管的阴极连接至所述第四二极管的阳极，并连接至所述第二电容的正极，所述第二电容的负极接地，所述变压器的次级线圈的第二端接地。
其中，所述电压转换电路还包括第三电容及第四电容，所述第三电容的正极连接至所述输入电压端，所述第三电容的负极接地，所述第四电容并联在所述第三电容的两端。
其中，所述背光驱动电路还包括第五电容及第六电容，所述第五电容的正极通过所述第二电阻连接至所述第二二极管的阴极，所述第五电容的负极接地，所述第六电容的正极连接至所述第三二极管的阴极，所述第六电容的负极接地。
其中，所述背光驱动电路还包括第五二极管、储能电感及第七电容，所述第五二极管的阳极通过所述储能电感连接至所述第三二极管及第四二极管的阴极，所述第五二极管的阴极连接至所述光源的阳极，所述光源的阴极连接至所述第三电开关的第一端，所述第五二极管的阴极还连接至所述第七电容的正极，所述第七电容的负极接地。
其中，所述升压开关、所述第二电开关及所述第三电开关均为NPN型晶体管，所述升压开关、所述第二电开关及所述第三电开关的控制端、第一端及第二端分别为栅极、漏极及源极，所述第一电开关为NPN型三极管，所述第一电开关的控制端、第一端及第二端分别为基极、集电极及发射极。
本发明还提供一种液晶显示器，包括光源及上述的背光驱动电路，所述背光驱动电路连接至所述光源。
本发明实施例具有如下优点或有益效果：
本发明的一种背光驱动电路，包括电压转换电路、PWM控制器、稳压二极管、第一电开关、光耦单元、升压开关及光源驱动组件，所述电压转换电路用于连接输入电压端，以接收输入电压，并对输入电压进行电压转换，所述电压转换电路还连接至所述光耦单元、PWM控制器、所述升压开关及液晶显示器的光源，以将转换后的电压输出给所述光耦单元、PWM控制器、所述升压开关及光源，所述PWM控制器用于控制所述电压转换电路的输出，所述光源驱动组件连接至所述升压开关及所述光源，以根据光源状况来控制所述升压开关的通断，所述稳压二极管的阴极连接至所述光耦单元，所述稳压二极管的阳 极连接至所述第一电开关的控制端，所述第一电开关的第一端连接至所述PWM控制器，所述第一电开关的第二端接地，当所述升压开关短路时，所述电压转换电路输出的电流增大，所述光耦单元反馈到所述稳压二极管的电压大于击穿电压，所述稳压二极管导通，进而所述第一电开关导通，所述PWM控制器停止工作以截止所述升压开关。所述升压开关表面温度降低，不但满足了安规的安全标准，还实现了过流保护。
附图说明
为了更清楚地说明本发明实施例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是本发明第一方案实施例提供的一种具有过流保护功能的背光驱动电路的电路图；
图2是本发明第二方案实施例提供的一种液晶显示器的框图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例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的一部分实施例，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做出创造性劳动的前提下所获得的所有其它实施例，都属于本发明保护的范围。
此外，以下各实施例的说明是参考附加的图示，用以例示本发明可用以实施的特定实施例。本发明中所提到的方向用语，例如，“上”、“下”、“前”、“后”、“左”、“右”、“内”、“外”、“侧面”等，仅是参考附加图式的方向，因此，使用的方向用语是为了更好、更清楚地说明及理解本发明，而不是指示或暗指所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
在本发明的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸地连接，或者一体地连接；可以是机械连接；可以是直接相连，也可以通过 中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本发明中的具体含义。
此外，在本发明的描述中，除非另有说明，“多个”的含义是两个或两个以上。若本说明书中出现“工序”的用语，其不仅是指独立的工序，在与其它工序无法明确区别时，只要能实现该工序所预期的作用则也包括在本用语中。另外，本说明书中用“～”表示的数值范围是指将“～”前后记载的数值分别作为最小值及最大值包括在内的范围。在附图中，结构相似或相同的用相同的标号表示。
请参阅图1，本发明第一方案实施例提供一种背光驱动电路100。所述背光驱动电路100应用于液晶显示器中，以驱动液晶显示器的光源进行发光的同时，还具有过流保护功能。
所述背光驱动电路100包括电压转换电路10、PWM控制器20、稳压二极管Z1、第一电开关Q1、光耦单元40、升压开关Qr及光源驱动组件30，所述电压转换电路10用于连接输入电压端Vin，以接收输入电压，并对输入电压进行电压转换，所述电压转换电路10还连接至所述光耦单元40、PWM控制器20、所述升压开关Qr及液晶显示器的光源，以将转换后的电压输出给所述光耦单元40、PWM控制器20、所述升压开关Qr及光源，所述PWM控制器20用于控制所述电压转换电路10的输出，所述光源驱动组件30连接至所述升压开关Qr及所述光源，以根据光源状况来控制所述升压开关Qr的通断，所述稳压二极管Z1的阴极连接至所述光耦单元40，所述稳压二极管Z1的阳极连接至所述第一电开关Q1的控制端，所述第一电开关Q1的第一端连接至所述PWM控制器20，所述第一电开关Q1的第二端接地。当所述升压开关Qr短路时，所述电压转换电路10输出的电流增大，所述光耦单元40反馈到所述稳压二极管Z1的电压大于击穿电压，所述稳压二极管Z1导通，进而所述第一电开关Q1导通，所述PWM控制器20停止工作来截止所述升压开关Qr。
具体地，所述PWM控制器20包括电压端、输出端、检测端及反馈端。所述PWM控制器20的电压端连接至所述电压转换电路10，以接收工作电压。所述PWM控制器20的电压端还连接至所述第一电开关Q1的第一端。所述PWM控制器20的输出端连接至所述电压转换电路10，以控制所述电压转换电路10的输出。所述PWM控制器20的检测端连接至所述电压转换电路10， 以在检测到所述电压转换电路10输出至所述检测端的电压大于预设值时，表明出现异常，所述PWM控制器停止工作。所述PWM控制器20的反馈端连接至所述光耦单元，以接收所述光耦单元40的反馈电压。
需要说明的是，所述光源为串联连接的发光二极管。所述发光二极管的阳极为所述光源的阳极。所述发光二极管的阴极为所述光源的阴极。所述电压转换电路10对所述输入电压进行电压转换后为所述光源提供电压，以使所述光源发光。在本实施例中，所述升压开关Qr短路是指所述升压开关Qr的栅极与漏极之间短路。当所述升压开关Qr短路后，会使得所述电压转换单元10输出的电流急剧升高，即流过所述光耦单元40的电流急剧升高。所述光耦单元40反馈到PWC控制器20的反馈端的电压升高。所述PWM控制器20的反馈端的电压大于所述稳压二极管Z1的击穿电压。所述稳压二极管Z1被击穿，所述第一电开关Q1导通。所述PWM控制器20的电压端接地。所述PWM控制器20停止工作，从而使得所述电压转换电路10停止输出，所述升压开关Qr截止，所述升压开关Qr表面温度降低，不但满足了安规的安全标准，还实现了过流保护。
进一步地，所述电压转换电路10包括变压器T、第二电开关Q2、第一电阻R1、第一电容C1、第一二极管D1、第二二极管D2及第二电阻R2，所述输入电压端Vin连接至所述变压器T的第一初级线圈的第一端，并通过所述第一电阻R1连接至所述第一二极管D1的阴极，所述第一电容C1并联在所述第一电阻R1的两端，所述第一二极管D1的阳极连接至所述第二电开关Q2的第一端，所述第一二极管D1的阳极还连接至所述变压器T的第一初级线圈的第二端，所述第二电开关Q2的控制端连接至所述PWM控制器20，所述第二电开关Q2的第二端接地，所述变压器T的第二初级线圈的第一端连接至所述第二二极管D2的阳极，所述第二二极管D2的阴极通过所述第二电阻R2连接至所述PWM控制器20的电压端，所述PWM控制器20的电压端连接至所述第一电开关Q1的第一端，所述变压器T的次级线圈连接至所述升压开关Qr的第一端。
需要说明的是，所述第一电阻R1、所述第一电容C1及所述第一二极管D1构成了RCD吸收单元。所述RCD吸收单元用于吸收所述第二电开关Q2的电压尖峰，防止所述第二电开关Q2被损坏。所述第二二极管D2及所述第 二电阻R2构成整流单元，以对输入值所述PWM控制器20的电压端的电压信号进行整流。
所述电压转换电路10还包括第八电阻R8。所述第二电开关Q2的第二端通过所述第八电阻R8接地。
需要说明的是，所述PWM控制器20的检测端检测到的电压即为所述第八电阻R8上的电压。
所述光源驱动组件30包括第三电开关Q3、控制单元32及第三电阻R3，所述第三电开关Q3的控制端连接至所述控制单元32，所述第三电开关Q3的第一端连接至所述光源，所述第三电开关Q3的第二端通过所述第三电阻R3接地，所述控制单元32还连接至所述升压开关Qr，以根据所述第三电阻R3的电压情况控制所述升压开关Qr的通断。
需要说明的是，所述控制单元32包括第一输出端、第二输出端及检测端。所述控制单元32的第一输出端连接至所述第三电开关Q3的控制端。所述控制单元32的第二输出端连接至升压开关Qr的控制端。所述控制单元32的检测端连接至所述升压开关Qr的第二端。所述控制单元32通过检测流过所述第三电阻R3上的电流情况控制所述第一输出端输出至所述第三电开关Q3的控制端的PWM信号的占空比，以维持所述光源的电流恒定。所述控制单元32的第二输出端用于输出PWM信号至所述升压开关Qr，以控制所述升压开关Qr的通断。所述控制单元32还用于检测所述升压开关Qr的第二端输出至所述控制单元32的电压，当该电压大于预设电压时，表明出现异常，所述控制单元32停止工作。
所述背光驱动电路还包括第九电阻R9。所述升压开关Qr的第二端还通过所述第九电阻R9接地。
需要说明的是，所述升压开关Qr的第二端输出至所述控制单元32的电压即为所述第九电阻R9上的电压。
所述光耦单元40包括第四电阻R4、第五电阻R5、第六电阻R6、第七电阻R7、电压调整器Z2及光耦U，所述第四电阻R4及所述第五电阻R5串联在所述变压器T的次级线圈与所述电压调整器Z2的第一端之间，所述电压调整器Z2的第二端接地，所述第六电阻R6及所述第七电阻R7连接至所述变压器T的次级线圈与地之间，所述电压调整器Z2的基准端连接至所述第六电阻 R6与所述第七电阻R7之间的节点，所述光耦U的发光二极管的阳极连接至所述第四电阻R4与所述第五电阻R5之间的节点，所述光耦U的发光二极管的阴极连接至所述第五电阻R5与所述电压调整器Z2之间的节点，所述光耦U的开关的第一端连接至所述PWM控制器20及所述稳压二极管Z1的阴极，所述光耦U的开关的第二端接地。
需要说明的是，所述电压调整器Z2的基准端提供基准电压。所述第四电阻R4、所述第五电阻R5、所述第六电阻R6及所述第七电阻R7均为分压电阻。
所述电压转换电路10还包括第三二极管D3、第四二极管D4及所述第二电容C2，所述第三二极管D3的阳极连接至所述第四二极管D4的阳极，并连接至所述变压器T的次级线圈的第一端，所述第三二极管D3的阴极连接至所述第四二极管D4的阳极，并连接至所述第二电容C2的正极，所述第二电容C2的负极接地，所述变压器T的次级线圈的第二端接地。
需要说明的是，所述第三二极管D3及所述第四二极管D4共同组成了整流器，以对所述变压器T输出的电压进行整流。所述第二电容C2起到储能的作用。
进一步地，所述电压转换电路10还包括第三电容C3及第四电容C4，所述第三电容C3的正极连接至所述输入电压端Vin，所述第三电容C3的负极接地，所述第四电容C4并联在所述第三电容C3的两端。
需要说明的是，所述第三电容C3起到储能的作用。所述第四电容C4起到高频滤波的作用。
所述背光驱动电路100还包括第五电容C5及第六电容C6，所述第五电容C5的正极通过所述第二电阻R2连接至所述第二二极管D2的阴极，所述第五电容C5的负极接地，所述第六电容C6的正极连接至所述第三二极管D3的阴极，所述第六电容C6的负极接地。
需要说明的是，所述第五电容C5及第六电容C6的作用均为储能。
所述背光驱动电路100还包括第五二极管D5、储能电感L及第七电容C7，所述第五二极管D5的阳极通过所述储能电感L连接至所述第三二极管D3及第四二极管D4的阴极，所述第五二极管D5的阴极连接至所述光源的阳极，所述光源的阴极连接至所述第三电开关Q3的第一端，所述第五二极管D5的 阴极还连接至所述第七电容C7的正极，所述第七电容C7的负极接地。
需要说明的是，所述第五二极管D5的作用为防止电流倒灌。所述第七电容C7起到储能的作用。
在本实施例中，所述升压开关Qr、所述第二电开关Q2及所述第三电开关Q3均为NPN型晶体管，所述升压开关Qr、所述第二电开关Q2及所述第三电开关Q3的控制端、第一端及第二端分别为栅极、漏极及源极，所述第一电开关Q1为NPN型三极管，所述第一电开关Q1的控制端、第一端及第二端分别为基极、集电极及发射极。在其他实施方式中，所述升压开关Qr、所述第二电开关Q2及所述第三电开关Q3也可以为其他类型的晶体管。
请参阅图2，本发明第二方案实施例提供一种液晶显示器200。所述液晶显示器200包括光源210及连接至所述光源210的背光驱动电路。所述背光驱动电路可以为上述第一方案实施例中的背光驱动电路100。由于所述背光驱动电路100的具体结构已经在上述第一方案中进行了详细的描述，故在此不再赘述。
在本实施例中，所述液晶显示器包括所述背光驱动电路100。所述背光驱动电路100包括电压转换电路10、PWM控制器20、稳压二极管Z1、第一电开关Q1、光耦单元40、升压开关Qr及光源驱动组件30，所述电压转换电路10用于连接输入电压端Vin，以接收输入电压，并对输入电压进行电压转换，所述电压转换电路10还连接至所述光耦单元40、PWM控制器20、所述升压开关Qr及液晶显示器的光源，以将转换后的电压输出给所述光耦单元40、PWM控制器20、所述升压开关Qr及光源，所述PWM控制器20用于控制所述电压转换电路10的输出，所述光源驱动组件30连接至所述升压开关Qr及所述光源，以根据光源状况来控制所述升压开关Qr的通断，所述稳压二极管Z1的阴极连接至所述光耦单元40，所述稳压二极管Z1的阳极连接至所述第一电开关Q1的控制端，所述第一电开关Q1的第一端连接至所述PWM控制器20，所述第一电开关Q1的第二端接地。当所述升压开关Qr短路时，所述电压转换电路10输出的电流增大，所述光耦单元40反馈到所述稳压二极管Z1的电压大于击穿电压，所述稳压二极管Z1导通，进而所述第一电开关Q1导通，所述PWM控制器20停止工作来截止所述升压开关Qr，因此，所述升压开关Qr表面温度降低，不但满足了安规的安全标准，还实现了过流保护。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不一定指的是相同的实施例或示例。而且，描述的具体特征、结构、材料或特点可以在任何的一个或多个实施例或示例中以合适的方式结合。
以上所述的实施方式，并不构成对该技术方案保护范围的限定。任何在上述实施方式的精神和原则之内所作的修改、等同替换和改进等，均应包含在该技术方案的保护范围之内。

Claims (18)

  1. 一种背光驱动电路，应用于液晶显示器中，其中，所述背光驱动电路包括电压转换电路、PWM控制器、稳压二极管、第一电开关、光耦单元、升压开关及光源驱动组件，所述电压转换电路用于连接输入电压端，以接收输入电压，并对输入电压进行电压转换，所述电压转换电路还连接至所述光耦单元、PWM控制器、所述升压开关及液晶显示器的光源，以将转换后的电压输出给所述光耦单元、PWM控制器、所述升压开关及光源，所述PWM控制器用于控制所述电压转换电路的输出，所述光源驱动组件连接至所述升压开关及所述光源，以根据光源状况来控制所述升压开关的通断，所述稳压二极管的阴极连接至所述光耦单元，所述稳压二极管的阳极连接至所述第一电开关的控制端，所述第一电开关的第一端连接至所述PWM控制器，所述第一电开关的第二端接地；
    当所述升压开关短路时，所述电压转换电路输出的电流增大，所述光耦单元反馈到稳压二极管的电压大于击穿电压，所述稳压二极管导通，进而所述第一电开关导通，所述PWM控制器停止工作以截止所述升压开关。
  2. 如权利要求1所述的背光驱动电路，其中，所述电压转换电路包括变压器、第二电开关、第一电阻、第一电容、第一二极管、第二二极管及第二电阻，所述输入电压端连接至所述变压器的第一初级线圈的第一端，并通过所述第一电阻连接至所述第一二极管的阴极，所述第一电容并联在所述第一电阻的两端，所述第一二极管的阳极连接至所述第二电开关的第一端，所述第一二极管的阳极还连接至所述变压器的第一初级线圈的第二端，所述第二电开关的控制端连接至所述PWM控制器，所述第二电开关的第二端接地，所述变压器的第二初级线圈的第一端连接至所述第二二极管的阳极，所述第二二极管的阴极通过所述第二电阻连接至所述PWM控制器的电压端，所述PWM控制器的电压端连接至所述第一电开关的第一端，所述变压器的次级线圈连接至所述升压开关的第一端。
  3. 如权利要求2所述的背光驱动电路，其中，所述光源驱动组件包括第三电开关、控制单元及第三电阻，所述第三电开关的控制端连接至所述控制单 元，所述第三电开关的第一端连接至所述光源，所述第三电开关的第二端通过所述第三电阻接地，所述控制单元还连接至所述升压开关，以根据所述第三电阻的电压情况控制所述升压开关的通断。
  4. 如权利要求3所述的背光驱动电路，其中，所述光耦单元包括第四电阻、第五电阻、第六电阻、第七电阻、电压调整器及光耦，所述第四电阻及所述第五电阻串联在所述变压器的次级线圈与电压调整器的第一端之间，所述电压调整器的第二端接地，所述第六电阻及所述第七电阻连接至所述变压器的次级线圈与地之间，所述电压调整器的基准端连接至所述第六电阻与所述第七电阻之间的节点，所述光耦的发光二极管的阳极连接至所述第四电阻与所述第五电阻之间的节点，所述光耦的发光二极管的阴极连接至所述第五电阻与所述电压调整器之间的节点，所述光耦的开关的第一端连接至所述PWM控制器及所述稳压二极管的阴极，所述光耦的开关的第二端接地。
  5. 如权利要求4所述的背光驱动电路，其中，所述电压转换电路还包括第三二极管、第四二极管及所述第二电容，所述第三二极管的阳极连接至所述第四二极管的阳极，并连接至所述变压器的次级线圈的第一端，所述第三二极管的阴极连接至所述第四二极管的阳极，并连接至所述第二电容的正极，所述第二电容的负极接地，所述变压器的次级线圈的第二端接地。
  6. 如权利要求5所述的背光驱动电路，其中，所述电压转换电路还包括第三电容及第四电容，所述第三电容的正极连接至所述输入电压端，所述第三电容的负极接地，所述第四电容并联在所述第三电容的两端。
  7. 如权利要求6所述的背光驱动电路，其中，所述背光驱动电路还包括第五电容及第六电容，所述第五电容的正极通过所述第二电阻连接至所述第二二极管的阴极，所述第五电容的负极接地，所述第六电容的正极连接至所述第三二极管的阴极，所述第六电容的负极接地。
  8. 如权利要求7所述的背光驱动电路，其中，所述背光驱动电路还包括第五二极管、储能电感及第七电容，所述第五二极管的阳极通过所述储能电感连接至所述第三二极管及第四二极管的阴极，所述第五二极管的阴极连接至所述光源的阳极，所述光源的阴极连接至所述第三电开关的第一端，所述第五二极管的阴极还连接至所述第七电容的正极，所述第七电容的负极接地。
  9. 如权利要求6所述的背光驱动电路，其中，所述升压开关、所述第二电开关及所述第三电开关均为NPN型晶体管，所述升压开关、所述第二电开关及所述第三电开关的控制端、第一端及第二端分别为栅极、漏极及源极，所述第一电开关为NPN型三极管，所述第一电开关的控制端、第一端及第二端分别为基极、集电极及发射极。
  10. 一种液晶显示器，其中，包括光源及背光驱动电路，所述背光驱动电路连接至所述光源，其中，所述背光驱动电路包括电压转换电路、PWM控制器、稳压二极管、第一电开关、光耦单元、升压开关及光源驱动组件，所述电压转换电路用于连接输入电压端，以接收输入电压，并对输入电压进行电压转换，所述电压转换电路还连接至所述光耦单元、PWM控制器、所述升压开关及液晶显示器的光源，以将转换后的电压输出给所述光耦单元、PWM控制器、所述升压开关及光源，所述PWM控制器用于控制所述电压转换电路的输出，所述光源驱动组件连接至所述升压开关及所述光源，以根据光源状况来控制所述升压开关的通断，所述稳压二极管的阴极连接至所述光耦单元，所述稳压二极管的阳极连接至所述第一电开关的控制端，所述第一电开关的第一端连接至所述PWM控制器，所述第一电开关的第二端接地；
    当所述升压开关短路时，所述电压转换电路输出的电流增大，所述光耦单元反馈到稳压二极管的电压大于击穿电压，所述稳压二极管导通，进而所述第一电开关导通，所述PWM控制器停止工作以截止所述升压开关。
  11. 如权利要求10所述的液晶显示器，其中，所述电压转换电路包括变压器、第二电开关、第一电阻、第一电容、第一二极管、第二二极管及第二电阻，所述输入电压端连接至所述变压器的第一初级线圈的第一端，并通过所述第一电阻连接至所述第一二极管的阴极，所述第一电容并联在所述第一电阻的两端，所述第一二极管的阳极连接至所述第二电开关的第一端，所述第一二极管的阳极还连接至所述变压器的第一初级线圈的第二端，所述第二电开关的控制端连接至所述PWM控制器，所述第二电开关的第二端接地，所述变压器的第二初级线圈的第一端连接至所述第二二极管的阳极，所述第二二极管的阴极通过所述第二电阻连接至所述PWM控制器的电压端，所述PWM控制器的电压端连接至所述第一电开关的第一端，所述变压器的次级线圈连接至所述升压 开关的第一端。
  12. 如权利要求11所述的液晶显示器，其中，所述光源驱动组件包括第三电开关、控制单元及第三电阻，所述第三电开关的控制端连接至所述控制单元，所述第三电开关的第一端连接至所述光源，所述第三电开关的第二端通过所述第三电阻接地，所述控制单元还连接至所述升压开关，以根据所述第三电阻的电压情况控制所述升压开关的通断。
  13. 如权利要求12所述的液晶显示器，其中，所述光耦单元包括第四电阻、第五电阻、第六电阻、第七电阻、电压调整器及光耦，所述第四电阻及所述第五电阻串联在所述变压器的次级线圈与电压调整器的第一端之间，所述电压调整器的第二端接地，所述第六电阻及所述第七电阻连接至所述变压器的次级线圈与地之间，所述电压调整器的基准端连接至所述第六电阻与所述第七电阻之间的节点，所述光耦的发光二极管的阳极连接至所述第四电阻与所述第五电阻之间的节点，所述光耦的发光二极管的阴极连接至所述第五电阻与所述电压调整器之间的节点，所述光耦的开关的第一端连接至所述PWM控制器及所述稳压二极管的阴极，所述光耦的开关的第二端接地。
  14. 如权利要求13所述的液晶显示器，其中，所述电压转换电路还包括第三二极管、第四二极管及所述第二电容，所述第三二极管的阳极连接至所述第四二极管的阳极，并连接至所述变压器的次级线圈的第一端，所述第三二极管的阴极连接至所述第四二极管的阳极，并连接至所述第二电容的正极，所述第二电容的负极接地，所述变压器的次级线圈的第二端接地。
  15. 如权利要求14所述的液晶显示器，其中，所述电压转换电路还包括第三电容及第四电容，所述第三电容的正极连接至所述输入电压端，所述第三电容的负极接地，所述第四电容并联在所述第三电容的两端。
  16. 如权利要求15所述的液晶显示器，其中，所述背光驱动电路还包括第五电容及第六电容，所述第五电容的正极通过所述第二电阻连接至所述第二二极管的阴极，所述第五电容的负极接地，所述第六电容的正极连接至所述第三二极管的阴极，所述第六电容的负极接地。
  17. 如权利要求16所述的液晶显示器，其中，所述背光驱动电路还包括第五二极管、储能电感及第七电容，所述第五二极管的阳极通过所述储能电感 连接至所述第三二极管及第四二极管的阴极，所述第五二极管的阴极连接至所述光源的阳极，所述光源的阴极连接至所述第三电开关的第一端，所述第五二极管的阴极还连接至所述第七电容的正极，所述第七电容的负极接地。
  18. 如权利要求15所述的液晶显示器，其中，所述升压开关、所述第二电开关及所述第三电开关均为NPN型晶体管，所述升压开关、所述第二电开关及所述第三电开关的控制端、第一端及第二端分别为栅极、漏极及源极，所述第一电开关为NPN型三极管，所述第一电开关的控制端、第一端及第二端分别为基极、集电极及发射极。
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