CN207925112U

CN207925112U - Backlight source drive circuit and liquid crystal display

Info

Publication number: CN207925112U
Application number: CN201820412553.1U
Authority: CN
Inventors: 汪慧
Original assignee: Guangzhou Shiyuan Electronics Thecnology Co Ltd
Current assignee: Guangzhou Shiyuan Electronics Thecnology Co Ltd
Priority date: 2018-03-26
Filing date: 2018-03-26
Publication date: 2018-09-28
Anticipated expiration: 2028-03-26

Abstract

The utility model discloses a backlight drive circuit and LCD. The backlight driving circuit includes: the dimming control module is connected with the PWM dimming module and the flyback control module and used for sending a first driving signal to the PWM dimming module and sending a second driving signal to the flyback control module when receiving a backlight source closing signal; the flyback control module is connected with the flyback transformer module and used for stopping sending a third driving signal to the flyback transformer module when receiving the second driving signal; the flyback transformer module is connected with the alternating current power supply and the PWM dimming module and used for responding to the condition that a third driving signal sent by the flyback control module is not received and stopping converting the alternating current sent by the alternating current power supply into the direct current; and the PWM dimming module is connected with the backlight source and used for stopping sending current pulses to the backlight source when receiving the first driving signal. The embodiment of the utility model provides a through adopting above-mentioned technical scheme, can simplify backlight drive circuit.

Description

Backlight source driving circuit and liquid crystal display

Technical field

The utility model is related to technical field of liquid crystal display more particularly to a kind of backlight source driving circuit and liquid crystal displays Device.

Background technology

With the development of electronic technology and liquid crystal technology, liquid crystal display is also more and more applied to television set and meter The output of data content is carried out in the electronic equipments such as calculation machine as its output device.

In order to realize the display function of liquid crystal display, it will usually the back of the body of installation and liquid crystal display in a liquid crystal display The backlight drive circuit that light source is connected is wide to drive the backlight of liquid crystal display to shine and carry out pulse to its illumination effect Degree modulation (Pulse Width Modulation, PWM).As shown in Figure 1, existing backlight source driving circuit is to liquid crystal display When backlight carries out PWM light modulations, it will usually first by AC power AC input alternating current, will be exchanged by flyback voltage changing module The alternating current of power supply AC input is converted to low-voltage DC, by boost chopper (BOOST booster circuits) by flyback transformation The low-voltage DC of module output boosts to the operating voltage needed for LED, and carries out PWM to backlight by PWM light-adjusting modules Light modulation, to realize the adjusting to backlight of LCD.

But inventor has found the prior art in the process of implementing the utility model that there are following technological deficiencies：It is existing The circuit structure of backlight source driving circuit is complex, and backlight source driving circuit is caused to need the printed wiring board occupied The area of (Printed Circuit Board, PCB) is larger, and required cost is higher.

Utility model content

In view of this, a kind of backlight source driving circuit of the utility model embodiment offer and liquid crystal display, existing to solve There is the technical problem that the circuit structure of backlight source driving circuit in technology is complex, occupied pcb board area is larger.

In a first aspect, the utility model embodiment provides a kind of backlight source driving circuit, including it is dimming controlling module, anti- Swash control module, flyback voltage changing module and PWM light-adjusting modules, wherein

The dimming controlling module is connected with the PWM light-adjusting modules and the flyback control module respectively, is used for When receiving backlight shutdown signal, is sent to the PWM light-adjusting modules and control the PWM light-adjusting modules are stopped first Drive signal, and the second drive signal for controlling the flyback control module and being stopped is sent to the flyback control module；

The flyback control module is connected with the flyback voltage changing module, for stopping when receiving the second drive signal Third drive signal is sent to the flyback voltage changing module, so that the flyback voltage changing module stops the friendship for sending AC power Galvanic electricity is converted to direct current；

The flyback voltage changing module is connected with AC power and the PWM light-adjusting modules respectively, in response to not connecing The case where receiving the third drive signal that the flyback control module is sent stops the alternating current for sending the AC power and turns It is changed to direct current；

The PWM light-adjusting modules are connected with backlight, for stopping when receiving the first drive signal to the backlight Source sends current impulse, and off working state is converted to by working condition to control the backlight.

Second aspect, the utility model embodiment additionally provide a kind of liquid crystal display, including backlight and this practicality Backlight source driving circuit described in new embodiment.

In the technical solution of above-mentioned driving backlight, dimming controlling module when receiving backlight shutdown signal to PWM light-adjusting modules send the first drive signal and sent to flyback control module for controlling that the PWM light-adjusting modules are stopped The second drive signal that the flyback control module is stopped is controlled, flyback control module is receiving dimming controlling module transmission The second drive signal when stop sending third drive signal to flyback voltage changing module, flyback voltage changing module do not receiving flyback In the case of the third drive signal that control module is sent, stop the alternating current that AC power is sent being converted to direct current, PWM Light-adjusting module stops sending current impulse to backlight when receiving the first drive signal of dimming controlling module transmission, to Control backlight is converted to off working state.The technical solution of above-mentioned driving backlight, when receiving backlight shutdown signal, Flyback control module, flyback voltage changing module, PWM light-adjusting modules and the back of the body in backlight drive circuit are controlled by dimming controlling module Light source is stopped, and can simplify the topological structure and controlling unit of backlight source driving circuit, reduces backlight source driving circuit institute The area of pcb board is occupied, it is cost-effective, improve the reliability of backlight source driving circuit.

Description of the drawings

By reading a detailed description of non-restrictive embodiments in the light of the attached drawings below, the utility model Other features, objects and advantages will become more apparent upon：

Fig. 1 is the structural schematic diagram of backlight source driving circuit in the prior art；

Fig. 2 is a kind of structural schematic diagram for backlight source driving circuit that the utility model embodiment provides；

Fig. 3 is a kind of electrical block diagram for dimming controlling module that the utility model embodiment provides；

Fig. 4 is a kind of electrical block diagram for flyback control module that the utility model embodiment provides.

Specific implementation mode

The utility model is described in further detail with reference to the accompanying drawings and examples.It is understood that herein Described specific embodiment is used only for explaining the utility model, rather than the restriction to the utility model.It further needs exist for It is bright, it illustrates only for ease of description, in attached drawing and the relevant part of the utility model rather than full content.

The utility model embodiment provides a kind of backlight source driving circuit.The backlight source driving circuit can be used for backlight It is driven.Fig. 2 is the structural schematic diagram for the backlight source driving circuit that the utility model embodiment provides.As shown in Fig. 2, the back of the body Light source driving circuit includes dimming controlling module 10, flyback control module 20, flyback voltage changing module 30 and PWM light-adjusting modules 40, Wherein,

The dimming controlling module 10 is connected with the PWM light-adjusting modules 40 and the flyback control module 20 respectively, The stopping of PWM light-adjusting modules 40 is controlled for when receiving backlight shutdown signal, being sent to the PWM light-adjusting modules 40 First drive signal of work, and sent to the flyback control module 20 and control what the flyback control module 20 was stopped Second drive signal；

The flyback control module 20 is connected with the flyback voltage changing module 30, for when receiving the second drive signal Stop sending third drive signal to the flyback voltage changing module 30, so that the flyback voltage changing module 30 stops AC power 50 alternating currents sent are converted to direct current；

The flyback voltage changing module 30 is connected with AC power 50 and the PWM light-adjusting modules 40 respectively, for responding In do not receive the third drive signal that the flyback control module 20 is sent the case where, stopping sends the AC power 50 Alternating current be converted to direct current；

The PWM light-adjusting modules 40 are connected with backlight 60, for stopping when receiving the first drive signal to described Backlight 60 sends current impulse, and off working state is converted to by working condition to control the backlight 60.

In the above scheme, backlight 60 can be the luminescent devices such as light emitting diode or organic electroluminescent piece.Light modulation Each drive signal that control module 10 and flyback control module 20 generate can be voltage signal or current signal etc., it is contemplated that The recipient of each drive signal detects the convenience when drive signal, and dimming controlling module 10 and flyback control module 20 generate Each drive signal preferably can be voltage signal.

Backlight shutdown signal can be generated by external control device or control module, typically can be by exterior arrangement For control backlight 60 opening with close PWM light adjusting circuits generate.In general, the PWM light adjusting circuits can be with this 10 direct or indirect connection of dimming controlling module in the backlight source driving circuit that embodiment provides, when the PWM light adjusting circuits connect The backlight out code of user's triggering is received, electronic equipment belonging to backlight 60 is received and (liquid crystal is typically such as installed Show television set or the computer etc. of device) central processing unit send backlight out code and/or detect conditions present accord with Backlight shutdown signal can be sent when closing the closedown condition of backlight 60 to the dimming controlling module 10 in the technical program.

Illustratively, dimming controlling module 10 can generate control PWM light modulation moulds when receiving backlight shutdown signal The second drive signal that the first drive signal and control flyback control module 20 that block 40 is stopped are stopped, and should First drive signal is sent to PWM light-adjusting modules 40, which is sent to flyback control module 20；Flyback controls Module 20 stops sending third drive signal to flyback voltage changing module 30 after receiving the second drive signal to control flyback change Die block 30 is stopped, and PWM light-adjusting modules 40 are then stopped after receiving the first drive signal to control backlight 60 Off working state is converted to, to which the modules that can be controlled based on dimming controlling module 10 in backlight source driving circuit are equal It is stopped, the certain module (typical such as flyback voltage changing module 30) in backlight source driving circuit is avoided to work on to backlight Damage caused by electronic equipment belonging to source 60.

The specific connection relation of each module of backlight source driving circuit provided in this embodiment can be arranged as required to, optional , the first input end of the flyback voltage changing module 30 can be connected with the output end of the AC power 50, and the flyback becomes First output end of die block 30 can control mould with the first input end of the PWM light-adjusting modules 40 and the flyback respectively The control terminal of block 20 is connected, and the second input terminal of the flyback voltage changing module 30 can be with the second of the PWM light-adjusting modules 40 Output end is connected, and the second output terminal of the flyback voltage changing module 30 can be connected with the input terminal of the AC power 50, institute Stating the third input terminal of flyback voltage changing module 30 can be connected with the output end of the flyback control module 20；The PWM light modulations First output end of module 40 can be connected with the input terminal of the backlight 60, the second input of the PWM light-adjusting modules 40 End can be connected with the output end of the backlight 60, and the third input terminal of the PWM light-adjusting modules 40 can be with the light modulation The output end of control module 10 is connected, and the third output end of the PWM light-adjusting modules 40 can be with the dimming controlling module 10 Input terminal be connected；The control terminal of the dimming controlling module 10 can be connected with the control terminal of the flyback control module 20.

In addition, dimming controlling module 10, when receiving backlight open signal, dimming controlling module 10 can control the back of the body Light source 60 is in working condition by off working state conversion.In general, when backlight 60 is in running order, the brightness adjustment control mould Block 10 can be also used for：The current PRF amplitude for the current impulse that PWM light-adjusting modules 40 are sent to backlight 60 is detected, control is generated Make the fourth drive signal of the duty ratio of the current current impulse and based on the current PRF amplitude and setting impulse amplitude life At the 5th drive signal of the control current PRF amplitude, and the fourth drive signal generated is sent to PWM light-adjusting modules 40, the 5th drive signal generated is sent to flyback control module 20, to control PWM light-adjusting modules 40 according to the duty ratio Current impulse is sent to the backlight 60 with the setting impulse amplitude, so as to be exported by adjusting PWM light-adjusting modules 40 The brightness of the duty ratio adjustment backlight 60 of current impulse, and the pulse by adjusting the 40 output current pulse of PWM light-adjusting modules Amplitude control backlight 60 works under the operating current of setting；It is connect correspondingly, flyback control module 20 can be also used for basis The 5th drive signal received generates the third drive signal of the voltage strength of the direct current of 30 conversion of control flyback voltage changing module, And the third drive signal is sent to flyback voltage changing module 30；Flyback voltage changing module 30 can be also used for receiving AC power 50 Alternating current is converted to voltage strength and direct current of the third drive signal with correspondence by the alternating current of output, and will The direct current being converted to is sent to the PWM light-adjusting modules 40；PWM light-adjusting modules 40 can also be used to convert in the direct current There is correspondence for duty ratio and the fourth drive signal that receives and current PRF amplitude and the direct current that receives Voltage strength has the current impulse of correspondence, and the current impulse is used to power for the backlight 60.

For example, it when the impulse amplitude to the 40 output current pulse of PWM light-adjusting modules is adjusted, can examine first The current PRF amplitude for surveying the current impulse that PWM light-adjusting modules 40 are exported to backlight 60, if the current PRF amplitude is more than It, then can be according to the correspondence of impulse amplitude and the 5th voltage strength of the 5th drive signal, suitably or less than setting pulse The 5th voltage strength of the 5th drive signal currently exported is increased or reduced, correspondingly, flyback control module 20 is receiving After 5th drive signal, can generate tertiary voltage intensity has the third drive signal of correspondence with the 5th voltage strength And the third drive signal is sent to flyback voltage changing module 30, the alternating current that flyback voltage changing module 30 exports AC power 50 Voltage strength and the tertiary voltage intensity are converted to there are the direct current of correspondence and is exported to PWM light-adjusting modules 40, thus, Dimming controlling module 10 can control the electricity of 40 output of PWM light-adjusting modules by adjusting the size of the 5th drive signal of its output The impulse amplitude of pulse is flowed, so by repeatedly adjusting, you can realize that 40 output pulse amplitude of PWM light-adjusting modules is setting pulse The current impulse of amplitude；If the current PRF amplitude is equal with setting impulse amplitude, dimming controlling module 10 can continue According to the 5th current voltage strength to flyback control module 20 export the 5th drive signal, with control PWM light-adjusting modules 40 after Continue with current pulse strength output current pulse.

Fig. 3 is a kind of electrical block diagram for dimming controlling module that the utility model embodiment provides.Such as Fig. 3 institutes Show, the utility model embodiment provide dimming controlling module may include brightness adjustment control chip U2, the first compensation network 101, First resistor R1, transistor Q1 and second resistance R2, wherein the PWM pins of the brightness adjustment control chip U2 are dimmed with the PWM The third input terminal of module 40 is connected, and the of the feedback pin FB of the brightness adjustment control chip U2 and the PWM light-adjusting modules 40 Three output ends are connected, the first end phase of the compensation pin COMP and first compensation network 101 of the brightness adjustment control chip U2 Even；The second end of first compensation network 101 respectively with the control terminal of the transistor Q1 (ends B) and the first resistor The first end of R1 is connected, and the third end of first compensation network 101 is connected and is grounded with the second end of the first resistor R1； The first end of the first resistor R1 is connected with the control terminal of the transistor Q1, the second end ground connection of the first resistor R1； The first end (C-terminal) of the transistor Q1 is connected with the first control terminal (ends F) of the flyback control module 20, the transistor The second end (ends E) of Q1 is connected with the first end of the second resistance R2, and electric current is by described first when the transistor Q1 is opened End flows to the second end；The second end of the second resistance R2 and 20 second control terminal of the flyback control module (ends G) phase Connect and is grounded.

Wherein, the control terminal of flyback control module 20 may include the first control terminal, the second control terminal and third control terminal (ends H), the first control terminal can be connected with the first end of transistor Q1, and the second control terminal can be with the of second resistance R2 Two ends are connected, and third control terminal can be connected with the first output end of flyback voltage changing module 30.

In the technical scheme, the first compensation network 101 and transistor Q1 can be selected or are arranged as needed.It can Choosing, the transistor Q1 can be triode or N-channel field-effect tube (being illustrated by taking triode as an example in Fig. 3).It is described First compensation network 101 may include 3rd resistor R3, the 4th resistance R4, the first capacitance C1 and the second capacitance C2, wherein described The first end of 3rd resistor R3 is connected with the compensation pin COMP of the brightness adjustment control chip U2, and the second of the 3rd resistor R3 End is connected with the first end of the first end of the 4th resistance R4 and the first capacitance C1 respectively；The 4th resistance R4's First end is connected with the first end of the first capacitance C1, and the second end of the 4th resistance R4 is respectively with the transistor Q1's The first end of control terminal, the first end of the second capacitance C2 and the first resistor R1 is connected；The first capacitance C1's Second end is connected and is grounded with the second end of the second end of the second capacitance C2 and the first resistor R1 respectively；Described The first end of two capacitance C2 is connected with the first end of the control terminal of the transistor Q1 and the first resistor R1 respectively, described The second end of second capacitance C2 is connected and is grounded with the second end of the first resistor R1.

Fig. 4 is a kind of electrical block diagram for flyback control module that the utility model embodiment provides.Such as Fig. 4 institutes Show, the flyback control module includes resistance unit 202, the second compensation network 201, the 5th resistance R5, photo-coupler PCB1, Six resistance R6, voltage reference chip UB1, the 7th resistance R7, the 8th resistance R8 and flyback control chip U1, wherein

The first end of the resistance unit 202 is connected with the first output end of the flyback voltage changing module 30, the resistance The second end of unit 202 respectively with the first end of the transistor Q1, the first end of second compensation network 201, the electricity The first end of the reference edge (ends R) and the 7th resistance R7 of pressing fiducial chip UB1 is connected；

The first end of second compensation network 201 respectively with the first end of the transistor Q1, the voltage reference core The first end of the reference edge of piece UB1 and the 7th resistance R7 are connected, the second end of second compensation network 201 respectively with The cathode of the second end of the 5th resistance R5, the second end of the photo-coupler PCB1 and the voltage reference chip UB1 (poles K) is connected；

The second end of the 5th resistance R5 respectively with the second end of the photo-coupler PCB1 and the voltage reference The cathode of chip UB1 is connected, the first end of the 5th resistance R5 respectively with the first end of the photo-coupler PCB1 and institute The second end for stating the 6th resistance R6 is connected；

The reference edge of the voltage reference chip UB1 respectively with the first end of the transistor Q1 and the 7th resistance The first end of R7 is connected, and the cathode of the voltage reference chip UB1 is connected with the second end of the photo-coupler PCB1, the electricity Press the anode (poles A) of fiducial chip UB1 respectively with the second end of the 7th resistance R7 and the second resistance R2 second End is connected and is grounded；

The first end of the 7th resistance R7 is connected with the first end of the transistor Q1, and the second of the 7th resistance R7 End is connected and is grounded with the second end of the second resistance R2；

The first end of the photo-coupler PCB1 is connected with the second end of the 6th resistance R6, the photo-coupler PCB1 Third end ground connection, the 4th end of the photo-coupler PCB1 passes through the 8th resistance R8 and controls chip U1's with the flyback Feedback pin FB is connected；

The first end of the 6th resistance R6 is connected with the output end VCC of accessory power supply；

The third input terminal of the gate-control signal pin GATE and the flyback voltage changing module 30 of the flyback control chip U1 It is connected.

In the present embodiment, accessory power supply can be DC power supply of the configuration in flyback control module outside or inside.Electricity Resistance unit 202 and voltage reference chip UB1 can be selected as needed, as may include in resistance unit 202 one or The resistance of multiple series connection and/or parallel connection includes with resistance unit 202 in Fig. 4 so as to accurately obtain required resistance value Illustrated for two resistance (the tenth resistance R10 and eleventh resistor R11) being serially connected, wherein the tenth resistance R10 and The resistance value of eleventh resistor R11 can be identical or different.Voltage reference chip UB1 can be the voltage references such as TL431 or TL432 Chip.In view of the matching with backlight source driving circuit provided in this embodiment, voltage reference chip UB1 is preferably TL431 Voltage reference chip.

In the technical scheme, the second compensation network 201 can be configured as needed, and optionally, described second mends It includes the 9th resistance R9, third capacitance C3 and the 4th capacitance C4 to repay network 201, wherein the first end of the 9th resistance R9 point Not with the first end of the transistor Q1, the second end of the resistance unit 202, the voltage reference chip UB1 reference edge, The first end of the 7th resistance R7 and the first end of the 4th capacitance C4 are connected, the second end of the 9th resistance R9 with The first end of the third capacitance C3 is connected；The second end of the third capacitance C3 respectively with the 5th resistance R5 second End, the second end of the photo-coupler PCB1, the cathode of the voltage reference chip UB1 and the 4th capacitance C4 second End is connected；The first end of the 4th capacitance C4 respectively with the first end of the transistor Q1, the resistance unit 202 second The first end at end, the reference edge of the voltage reference chip UB1 and the 7th resistance R7 is connected；The 4th capacitance C4's Second end respectively with the second end of the 5th resistance R5, the second end of the photo-coupler PCB1 and the voltage reference core The cathode of piece UB1 is connected.

Here, each capacitor (such as the first capacitance C1, the second capacitance in backlight source driving circuit provided in this embodiment C2, third capacitance C3 and the 4th capacitance C4) material and type can select as needed, it is optionally, provided in this embodiment Capacitor in backlight source driving circuit can be polystyrene capacitance.

Illustratively, by taking transistor Q1 is triode, voltage reference chip UB1 is TL431 voltage reference chips as an example, When being controlled, brightness adjustment control chip U2 can sample the current impulse of PWM light-adjusting modules 40, determining according to sampling The relative size of the current PRF amplitude of current impulse and setting impulse amplitude determines the big of the voltage of compensation pin COMP outputs It is small and export corresponding COMP voltages；First compensation network 101 compensates the COMP voltages received to enhance COMP electricity The stability of pressure, and by the base stage of the COMP voltage outputs after compensation to triode, the size of COMP voltages can control three poles The size of pipe base current, the size of transistor base electric current can control the size of transistor collector electric current, collector Electric current is converted into voltage signal by second resistance R2, and believes with the Voltage Feedback of 30 first output end of flyback voltage changing module output Number VLED+ is superimposed, and the voltage after superposition is carried out by TL431 voltage reference chips and its corresponding second compensation network 201 It adjusts, and flyback is fed back to by photo-coupler PCB1 and controls chip U1, generated to flyback to control flyback control chip U1 The third drive signal that voltage changing module 30 is controlled, to control the alternating current that flyback voltage changing module 30 exports AC power 50 Be converted to corresponding direct current.

As a result, when receiving backlight shutdown signal, PWM light-adjusting modules 40 are controlled by the first drive signal and stop work To make, and reduces COMP voltages, transistor base electric current reduces, and transistor collector electric current also reduces (or being reduced to 0) therewith, The voltage of TL431 voltage reference chip reference edges increases, and is increased by the electric current of photo-coupler PCB1 primary sides, photo-coupler PCB1 The brightness of primary side increases, and then the impedance on photo-coupler PCB1 pairs side reduces, and the electric current on photo-coupler PCB1 pairs side increases, and the 8th The voltage of resistance R8 increases, and the feedback voltage for feeding back to flyback control chip U1 feedback pins FB increases, when the feedback voltage is super When crossing the threshold value of flyback control chip U1, flyback control chip U1 is turned off and is stopped sending third driving to flyback voltage changing module 30 Signal, flyback voltage changing module are stopped；When receiving backlight open signal, PWM is controlled by corresponding drive signal Light-adjusting module 40 is started to work, and increases COMP voltages, and transistor base electric current increases, and transistor collector electric current also increases therewith Greatly, the voltage of TL431 voltage reference chips reference edge reduces, and is reduced by the electric current of photo-coupler PCB1 primary sides, photo-coupler The brightness of PCB1 primary sides reduces, and then the impedance on photo-coupler PCB1 pairs side increases, and the electric current on photo-coupler PCB1 pairs side reduces, The voltage at the 8th both ends resistance R8 reduces, and the feedback voltage for feeding back to flyback control chip U1 feedback pins FB reduces, when this is anti- When feedthrough voltage is reduced under the threshold value or the threshold value of flyback control chip U1, flyback controls chip U1 and starts to work, to flyback Voltage changing module 30 sends third drive signal driving flyback voltage changing module 30 and starts to work.

The backlight source driving circuit that the utility model embodiment provides, dimming controlling module are receiving backlight closing letter Number when sent to PWM light-adjusting modules and control the first drive signal for being stopped of the PWM light-adjusting modules and control mould to flyback Block, which is sent, controls the second drive signal that the flyback control module is stopped, and flyback control module is receiving brightness adjustment control mould Stop sending third drive signal to flyback voltage changing module when the second drive signal that block is sent, flyback voltage changing module is not receiving In the case of the third drive signal sent to flyback control module, stop the alternating current that AC power is sent being converted to direct current Electricity, PWM light-adjusting modules stop sending electric current arteries and veins to backlight when receiving the first drive signal of dimming controlling module transmission Punching, off working state is converted to control backlight.The present embodiment is receiving backlight by using above-mentioned technical proposal When shutdown signal, pass through the flyback control module in dimming controlling module control backlight drive circuit, flyback voltage changing module, PWM Light-adjusting module and backlight are stopped, and can simplify the topological structure and controlling unit of backlight source driving circuit, reduce backlight The area of pcb board occupied by source driving circuit, it is cost-effective, improve the reliability of backlight source driving circuit.

In addition, the utility model embodiment additionally provides a kind of liquid crystal display, which includes backlight, also Include the backlight source driving circuit that the utility model above-described embodiment provides, using being integrated with above-mentioned backlight source driving circuit Liquid crystal display can not only save cost of manufacture, can be with the light modulation of the realization backlight of high efficient and reliable.

Note that above are only the preferred embodiment and institute's application technology principle of the utility model.Those skilled in the art's meeting Understand, the utility model is not limited to specific embodiment described here, can carry out for a person skilled in the art various bright Aobvious variation is readjusted and is substituted without departing from the scope of protection of the utility model.Therefore, although passing through above example The utility model is described in further detail, but the utility model is not limited only to above example, is not departing from Can also include other more equivalent embodiments in the case that the utility model is conceived, and the scope of the utility model is by appended Right determine.

Claims

1. a kind of backlight source driving circuit, which is characterized in that become pressing mold including dimming controlling module, flyback control module, flyback Block and PWM light-adjusting modules, wherein

The dimming controlling module is connected with the PWM light-adjusting modules and the flyback control module respectively, for receiving When to backlight shutdown signal, is sent to the PWM light-adjusting modules and control the first driving that the PWM light-adjusting modules are stopped Signal, and the second drive signal for controlling the flyback control module and being stopped is sent to the flyback control module；

The flyback control module is connected with the flyback voltage changing module, for stopping when receiving the second drive signal to institute It states flyback voltage changing module and sends third drive signal, so that the flyback voltage changing module stops the alternating current for sending AC power Be converted to direct current；

The flyback voltage changing module is connected with AC power and the PWM light-adjusting modules respectively, in response to not receiving The case where third drive signal that the flyback control module is sent, stopping are converted to the alternating current that the AC power is sent Direct current；

The PWM light-adjusting modules are connected with backlight, are sent out to the backlight for stopping when receiving the first drive signal Current impulse is sent, off working state is converted to by working condition to control the backlight.

2. circuit according to claim 1, which is characterized in that the first input end of the flyback voltage changing module and the friendship The output end in galvanic electricity source is connected, and the first output end of the flyback voltage changing module is defeated with the first of the PWM light-adjusting modules respectively The control terminal for entering end and the flyback control module is connected, the second input terminal of the flyback voltage changing module and the PWM tune The second output terminal of optical module is connected, the second output terminal of the flyback voltage changing module and the input terminal phase of the AC power Even, the third input terminal of the flyback voltage changing module is connected with the output end of the flyback control module；

First output end of the PWM light-adjusting modules is connected with the input terminal of the backlight, and the second of the PWM light-adjusting modules Input terminal is connected with the output end of the backlight, third input terminal and the dimming controlling module of the PWM light-adjusting modules Output end be connected, the third output end of the PWM light-adjusting modules is connected with the input terminal of the dimming controlling module；

The control terminal of the dimming controlling module is connected with the control terminal of the flyback control module.

3. circuit according to claim 2, which is characterized in that the dimming controlling module includes brightness adjustment control chip, One compensation network, first resistor, transistor and second resistance, wherein

The PWM pins of the brightness adjustment control chip are connected with the third input terminal of the PWM light-adjusting modules, the brightness adjustment control core The feedback pin of piece is connected with the third output end of the PWM light-adjusting modules, the compensation pin of the brightness adjustment control chip and institute The first end for stating the first compensation network is connected；

The second end of first compensation network respectively with the control terminal of the transistor and the first end of the first resistor It is connected, the third end of first compensation network is connected and is grounded with the second end of the first resistor；

The first end of the first resistor is connected with the control terminal of the transistor, the second end ground connection of the first resistor；

The first end of the transistor is connected with the first control terminal of the flyback control module, the second end of the transistor with The first end of the second resistance is connected, and electric current flows to the second end by the first end when transistor is opened；

The second end of the second resistance is connected and is grounded with second control terminal of flyback control module.

4. circuit according to claim 3, which is characterized in that first compensation network includes 3rd resistor, the 4th electricity Resistance, the first capacitance and the second capacitance, wherein

The first end of the 3rd resistor is connected with the compensation pin of the brightness adjustment control chip, the second end of the 3rd resistor It is connected respectively with the first end of the first end of the 4th resistance and first capacitance；

The first end of 4th resistance is connected with the first end of first capacitance, the second end of the 4th resistance respectively with The first end of the control terminal of the transistor, the first end of second capacitance and the first resistor is connected；

The second end of first capacitance respectively with the second end of second capacitance and the second end phase of the first resistor Connect and is grounded；

The first end of second capacitance is connected with the first end of the control terminal of the transistor and the first resistor respectively, The second end of second capacitance is connected and is grounded with the second end of the first resistor.

5. circuit according to claim 3, which is characterized in that the transistor is triode or N-channel field-effect tube.

6. circuit according to claim 3, which is characterized in that the flyback control module includes resistance unit, the second benefit Repay network, the 5th resistance, photo-coupler, the 6th resistance, voltage reference chip, the 7th resistance, the 8th resistance and flyback control core Piece, wherein

The first end of the resistance unit is connected with the first output end of the flyback voltage changing module, and the second of the resistance unit Hold the reference edge with the first end of the transistor, the first end of second compensation network, the voltage reference chip respectively And the first end of the 7th resistance is connected；

The first end of second compensation network reference edge with the first end of the transistor, the voltage reference chip respectively And the first end of the 7th resistance is connected, the second end of second compensation network respectively with the 5th resistance second The cathode at end, the second end of the photo-coupler and the voltage reference chip is connected；

The second end of 5th resistance cathode with the second end of the photo-coupler and the voltage reference chip respectively Be connected, the first end of the 5th resistance respectively with the first end of the photo-coupler and the second end phase of the 6th resistance Even；

The reference edge of the voltage reference chip respectively with the first end of the transistor and the first end of the 7th resistance It is connected, the cathode of the voltage reference chip is connected with the second end of the photo-coupler, the anode of the voltage reference chip It is connected and is grounded with the second end of the second end of the 7th resistance and the second resistance respectively；

The first end of 7th resistance is connected with the first end of the transistor, the second end of the 7th resistance and described the The second end of two resistance is connected and is grounded；

The first end of the photo-coupler is connected with the second end of the 6th resistance, the third end ground connection of the photo-coupler, The feedback pin that 4th end of the photo-coupler controls chip by the 8th resistance with the flyback is connected；

The first end of 6th resistance is connected with the output end of accessory power supply；

The gate-control signal pin of the flyback control chip is connected with the third input terminal of the flyback voltage changing module.

7. circuit according to claim 6, which is characterized in that second compensation network includes the 9th resistance, third electricity Hold and the 4th capacitance, wherein

The first end of 9th resistance respectively with the first end of the transistor, the second end of the resistance unit, the electricity The first end of the reference edge of fiducial chip, the first end of the 7th resistance and the 4th capacitance is pressed to be connected, the described 9th The second end of resistance is connected with the first end of the third capacitance；

The second end of the third capacitance respectively with the second end of the 5th resistance, second end of the photo-coupler, described The second end of the cathode of voltage reference chip and the 4th capacitance is connected；

The first end of 4th capacitance respectively with the first end of the transistor, the second end of the resistance unit, the electricity The first end of the reference edge and the 7th resistance of pressing fiducial chip is connected；The second end of 4th capacitance respectively with it is described The cathode of the second end of 5th resistance, the second end of the photo-coupler and the voltage reference chip is connected.

8. circuit according to claim 6, the resistance unit includes at least one resistance.

9. circuit according to claim 6, which is characterized in that the voltage reference chip is TL431 voltage reference chips.

10. a kind of liquid crystal display, which is characterized in that including backlight and backlight described in any one of claim 1-9 Source driving circuit.