CN105405410A - Backlight driving circuit and driving method and display device thereof - Google Patents
Backlight driving circuit and driving method and display device thereof Download PDFInfo
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- CN105405410A CN105405410A CN201510809583.7A CN201510809583A CN105405410A CN 105405410 A CN105405410 A CN 105405410A CN 201510809583 A CN201510809583 A CN 201510809583A CN 105405410 A CN105405410 A CN 105405410A
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Abstract
The embodiment of the invention provides a backlight driving circuit and a driving method and display device thereof, and relates to the technical field of display. High energy consumption caused by the low voltage transition ratio can be avoided, the structure of the backlight driving circuit is simplified, and the cost is reduced. The backlight driving circuit comprises a flyback control module, a filter rectifier module, a light-emitting module, a backlight control module and a switch module. The flyback control module supplies voltage to a first voltage end and a second voltage end. The filter rectifier module conducts filter rectification on the voltage output by the first voltage end, and the filter rectified voltage is output to the light-emitting module. The backlight control module is triggered to output a PWM signal to the switch module under the control of the first voltage end or the second voltage end. The switch module is turned on or turned off under the control of the PWM signal, and the light-emitting module is driven to emit light in the on-state. The backlight driving circuit and the driving method and the display device thereof are used for driving backlight to emit the light.
Description
Technical field
The present invention relates to display technique field, particularly relate to a kind of backlight drive circuit and driving method, display device.
Background technology
LCD (LiquidCrystalDisplay, liquid crystal display) is a kind of passive luminescent device, needs BLU (BacklightUnite, backlight module) to provide light source to make it show image to liquid crystal display.At present, the back light source technique that liquid crystal display mainly adopts comprises: CCFL (ColdCathodeFluorescentLamp, cold-cathode tube) and LED (LightEmittingDiodes, light emitting diode).
In prior art, the backlight drive circuit of aforementioned display device can comprise flyback power supply, backlight (being such as made up of LED lamp bar), and controls the control circuit etc. of backlight luminescence.Wherein, flyback power supply can be powered to the mainboard of display.But due to the operating voltage of the more above-mentioned control circuit of operating voltage of backlight high.Therefore, above-mentioned backlight drive circuit can also comprise BOOST circuit (TheBoostConverter, boost type varying circuit), main board power supply voltage for exporting flyback power supply carries out boosting process, with light source power supply of supporting or opposing, or comprise BUCK circuit (TheBuckConverter, Buck conversion circuit), main board power supply voltage for exporting flyback power supply carries out step-down process, to control control circuit.
Concrete, generally can boost or reduced pressure operation to the voltage that flyback power supply exports by arranging afterflow inductance in BOOST circuit or BUCK circuit, but boosting and step-down process in, the conversion efficiency of voltage is not 100%, and energy consumption therefore can be caused to increase.And circuit structure can be caused complicated due to the existence of afterflow inductance, cost is higher.
Summary of the invention
Embodiments of the invention provide a kind of backlight drive circuit and driving method, display device, can avoid the low high energy consumption caused of voltage transitions rate, and can simplify the structure of backlight drive circuit, reduce costs.
For achieving the above object, embodiments of the invention adopt following technical scheme:
The one side of the embodiment of the present invention, provides a kind of backlight drive circuit, comprises flyback control module, filter rectification module, light emitting module, backlight control module, switch module; Described flyback control module provides voltage to the first voltage end and the second voltage end; The voltage of wherein said first voltage end is greater than the voltage of described second voltage end; First voltage end and described light emitting module described in described filter rectification model calling, carry out filter rectification for the voltage exported described first voltage end, and export the voltage after filter rectification to described light emitting module; Described backlight control module connects described first voltage end and described switch module, under the control of described first voltage end, triggers described backlight control module to described switch module output pulse width modulation signal; Or described backlight control module connects described second voltage end and described switch module, under the control of described second voltage end, triggers described backlight control module to described switch module output pulse width modulation signal; Described switch module also connects described light emitting module, for conducting or cut-off under the control of described pulse width modulating signal, and under the state of conducting, drives described light emitting module luminous.
The another aspect of the embodiment of the present invention, provides a kind of display device, comprises any one backlight drive circuit as above.
The another aspect of the embodiment of the present invention, there is provided a kind of for driving the method for any one backlight drive circuit as described above, comprise: flyback control module provides synchronizing signal by the first voltage end and the second voltage end to backlight control module, and provide operating voltage by described first voltage end to light emitting module; Described backlight control module is according to described synchronizing signal opening switch module, and under the state that described switch module is opened, described light emitting module is luminous; Described backlight control module closes described switch module according to parameter preset, and described light emitting module is closed.
The embodiment of the present invention provides a kind of backlight drive circuit and driving method, display device, and this backlight drive circuit comprises flyback control module, filter rectification module, light emitting module, backlight control module, switch module.Concrete, flyback control module provides voltage to the first voltage end and the second voltage end.Wherein, the voltage of the first voltage end is greater than the voltage of the second voltage end.On this basis, filter rectification model calling first voltage end and light emitting module, carry out filter rectification for the voltage exported the first voltage end, and export the voltage after filter rectification to light emitting module.Backlight control module connects the first voltage end and switch module, under the control of the first voltage end, triggers backlight control module to switch module output pulse width modulation signal; Or backlight control module connects the second voltage end and switch module, under the control of the second voltage end, trigger backlight control module to switch module output pulse width modulation signal.Switch module also connects light emitting module, for conducting or cut-off under the control of pulse width modulating signal, and under the state of conducting, drives light emitting module luminous.
Because the first voltage end of backlight control module and flyback control module or the second voltage end are connected, therefore, the voltage signal that flyback control module exports from the first voltage end or the second voltage end can be synchronized to backlight control module, make the duration that the first voltage end or the second voltage end can be opened by backlight control module gauge tap module, and can be determined the moment that switch module is closed by the parameter preset of backlight control module.In the case, the pulse width modulating signal that backlight control module exports, namely its dutycycle can be determined by above-mentioned parameter preset.Wherein, above-mentioned pulse width modulating signal can drive light emitting module to carry out luminescence.Therefore, the backlight drive circuit that the embodiment of the present invention provides is synchronized to backlight control module by the voltage signal the first voltage end or the second voltage end exported, while powering to luminescence unit, backlight control module output pulse width modulation signal can also be controlled, drive light emitting module luminous by switch module.
In sum, without the need to boosting or reduced pressure operation to the output voltage of flyback control module in above-mentioned driving process, therefore in backlight drive circuit without the need to arranging afterflow inductance.So, without the need to carrying out the conversion of boost in voltage or step-down between the voltage that the voltage of the first voltage end output of flyback control module and light emitting module receive, magnitude of voltage is equal, so can avoid the high energy consumption caused in voltage transitions process.In addition, due to without the need to arranging afterflow inductance, therefore circuit structure is simple, and cost is lower.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
The structural representation of a kind of backlight drive circuit that Fig. 1 a provides for the embodiment of the present invention;
The structural representation of the another kind of backlight drive circuit that Fig. 1 b provides for the embodiment of the present invention;
Fig. 2 is for being provided with the structural representation of main board power supply module in the backlight drive circuit shown in Fig. 1;
Fig. 3 a is a kind of pwm signal oscillogram of backlight control module input in Fig. 1 a, 1b or 2;
Fig. 3 b is the another kind of pwm signal oscillogram of backlight control module input in Fig. 1 a, 1b or 2;
Fig. 4 is the structural representation of flyback control module in Fig. 1 a, 1b or 2;
A kind of detailed construction schematic diagram that Fig. 5 a is the backlight drive circuit shown in Fig. 2;
Fig. 5 b is the signal timing diagram for the backlight drive circuit shown in control chart 5a;
The another kind of detailed construction schematic diagram that Fig. 6 a is the backlight drive circuit shown in Fig. 2;
Fig. 6 b is the signal timing diagram for the backlight drive circuit shown in control chart 6a;
The driving method process flow diagram of a kind of driving circuit that Fig. 7 provides for the embodiment of the present invention.
Reference numeral:
10-flyback control module; 20-filter rectification module; 201-electrolysis filtering submodule; 30-light emitting module; 40-backlight control module; 50-switch module; 60-main board power supply module; 70-overvoltage protective module; 71-under-voltage protective module.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
The embodiment of the present invention provides a kind of backlight drive circuit, as shown in Figure 1 a or 1b, comprises flyback control module 10, filter rectification module 20, light emitting module 30, backlight control module 40 and switch module 50.
Concrete, flyback control module 10 provides voltage to the first voltage end V1 and the second voltage end V2.Wherein, the voltage of the first voltage end V1 is greater than the voltage of the second voltage end V2.
Filter rectification module 20 connects the first voltage end V1 and light emitting module 30, carries out filter rectification, and export the voltage after filter rectification to light emitting module 30 for the voltage exported the first voltage end V1.Thus the noise of the output voltage of the first voltage end V1 can be removed by filter rectification module 20, guarantee the voltage stabilization inputting light emitting module 30, to improve the brightness constancy of light emitting module 30.
Backlight control module 40 as shown in Figure 1 b, connect the first voltage end V1 and switch module 50, for under the control of the first voltage end V1, trigger backlight control module 40 to switch module 50 output pulse width modulation signal (English full name, Pulse-WidthModulation, English abbreviation: PWM).Or backlight control module 40 as shown in Figure 1a, connects the second voltage end V2 and switch module 50, under the control of the second voltage end V2, trigger backlight control module 40 to switch module 50 output pwm signal.
Switch module 50 also connects light emitting module 30, for conducting or cut-off under the control of pwm signal, and under the state of conducting, drives light emitting module 30 luminous.
It should be noted that, first, electric main (such as voltage is 220V, and frequency is the AC signal of 50HZ) can by obtaining a high direct voltage (in such as Fig. 4, Fig. 5 a and Fig. 6 a Vdc=300V) after rectification, filtering process.This flyback control module 10 can accept above-mentioned 300V high direct voltage, and is powered to the first voltage end V1 and the second voltage end V2 by transformer T.
Concrete, the voltage of this first voltage end V1 can as the operating voltage of light emitting module 30, and therefore its size is determined by light emitting module 30.Such as, when this light emitting module 30 is made up of LED lamp bar, the output voltage of above-mentioned first voltage end V1 is relevant with the quantity of this LED lamp bar, and the quantity of LED lamp bar is larger, and the output voltage of the first voltage end V1 is higher, otherwise less.
The voltage that second voltage end V2 exports can as the main board power supply voltage of display.On this basis, as shown in Figure 2, above-mentioned backlight drive circuit can also comprise the main board power supply module 60 connecting above-mentioned second voltage end V2, for the signal according to the second voltage end V2, exports main board power supply voltage (such as 12V).
The second, pwm signal is the square wave model with certain dutycycle, Fig. 3 a, 3b indicate respectively dutycycle be 90% and dutycycle be the square wave of 10%.So, under the state that above-mentioned switch module 50 is opened, the fluorescent lifetime of light emitting module 30 can receive the control of said PWM signal.Such as, when to receive dutycycle be the pwm signal of 90% to light emitting module 30, light emitting module 30 has the time of 90% to be in opening in a light period.Or when to receive dutycycle be the pwm signal of 10% to light emitting module 30, light emitting module 30 has the time of 10% to be in opening in a light period T.The time that light emitting module 30 is opened is longer, and the brightness of light emitting module 30 in a light period is higher.Therefore, can be regulated by the brightness of dutycycle to backlight luminescence module 30 setting pwm signal.
Three, above-mentioned light emitting module 30 can be made up of CCFL or LED.The present invention does not limit this.Due to LED have that brightness is high, excitation is high, the life-span is long, good reliability, without multiple advantages such as mercury pollution, in the embodiment of the present invention, preferred LED lamp bar is as light emitting module 30.
Four, because the first voltage end V1 is used for providing operating voltage to light emitting module 30, and the second voltage end V2 may be used for generating main board power supply voltage.Therefore the voltage that the second voltage end V2 exports is less than the voltage that the first voltage end V1 exports.In the case, because the operating voltage of backlight control module 40 is much smaller than light emitting module 30, therefore preferred backlight control module 40 is connected with the second voltage end V2, thus the synchronizing voltage accessing backlight control module 40 can be avoided excessive, causes the life-span of device to decline.Following examples of the present invention are all to be connected with the second voltage end V2 the explanation carried out for backlight control module 40.
The embodiment of the present invention provides a kind of backlight drive circuit, and this backlight drive circuit comprises flyback control module, filter rectification module, light emitting module, backlight control module, switch module.Concrete, flyback control module provides voltage to the first voltage end and the second voltage end.Wherein, the voltage of the first voltage end is greater than the voltage of the second voltage end.On this basis, filter rectification model calling first voltage end and light emitting module, carry out filter rectification for the voltage exported the first voltage end, and export the voltage after filter rectification to light emitting module.Backlight control module connects the first voltage end and switch module, under the control of the first voltage end, triggers backlight control module to switch module output pulse width modulation signal; Or backlight control module connects the second voltage end and switch module, under the control of the second voltage end, trigger backlight control module to switch module output pulse width modulation signal.Switch module also connects light emitting module, for conducting or cut-off under the control of pulse width modulating signal, and under the state of conducting, drives light emitting module luminous.
Because the first voltage end of backlight control module and flyback control module or the second voltage end are connected, therefore, the voltage signal that flyback control module exports from the first voltage end or the second voltage end can be synchronized to backlight control module, make the duration that the first voltage end or the second voltage end can be opened by backlight control module gauge tap module, and can be determined the moment that switch module is closed by the parameter preset of backlight control module.In the case, the pulse width modulating signal that backlight control module exports, namely its dutycycle can be determined by above-mentioned parameter preset.Wherein, above-mentioned pulse width modulating signal can drive light emitting module to carry out luminescence.Therefore, the backlight drive circuit that the embodiment of the present invention provides is synchronized to backlight control module by the voltage signal the first voltage end or the second voltage end exported, while powering to luminescence unit, backlight control module output pulse width modulation signal can also be controlled, drive light emitting module luminous by switch module.
In sum, without the need to boosting or reduced pressure operation to the output voltage of flyback control module in above-mentioned driving process, therefore in backlight drive circuit without the need to arranging afterflow inductance.So, without the need to carrying out the conversion of boost in voltage or step-down between the voltage that the voltage of the first voltage end output of flyback control module and light emitting module receive, magnitude of voltage is equal, so can avoid the high energy consumption caused in voltage transitions process.In addition, due to without the need to arranging afterflow inductance, therefore circuit structure is simple, and cost is lower.
Further, above-mentioned flyback control module 10, as shown in Figure 4, can comprise transformer T, the secondary coil of this transformer T have the first loop 1. with second servo loop 2..Wherein, the first loop the first terminal I is 1. connected with the first voltage end V1, and the second terminal II is electrically connected with switch module 50.Second servo loop the first terminal I ' is 2. connected with the second voltage end V2, the second terminal II ' ground connection.So, 1. above-mentioned first loop may be used for the voltage providing the first voltage end V1 to light emitting module 30.And 2. second servo loop may be used for the voltage providing the second voltage end V2 to above-mentioned main board power supply module 60.Wherein, because required voltage when light emitting module 30 works is greater than the final main board power supply voltage exported of main board power supply module 60, namely the output voltage of above-mentioned first voltage end V1 is greater than the output voltage of the second voltage end V2, forms the first loop coil lock number 1. and be greater than second servo loop coil lock number 2. in the secondary wire of therefore above-mentioned transformer T.
In the case, as shown in Fig. 5 a or 6a, above-mentioned filter rectification module 20 comprises the commutation diode VD1 that may be used for realizing rectification function, and for realizing at least one-level electrolysis filtering submodule 201 of electrolysis filter function.
It should be noted that, for the backlight drive circuit being provided with BOOST circuit or BUCK circuit of the prior art, because above-mentioned BOOST circuit or BUCK circuit and flyback sourse are two independently circuit structures, therefore in order to improve the stability of backlight driver electric current, not only need to carry out first order electrolysis filtering to the output signal of flyback power supply, also need to carry out the second pole electrolysis filtering, to reduce the high frequency noise of backlight Received signal strength to the signal in BOOST circuit or BUCK circuit.So, be provided with in prior art in the backlight drive circuit of BOOST circuit or BUCK circuit and at least need to arrange two-stage electrolysis filtering.
But, in the backlight drive circuit that the embodiment of the present invention provides, flyback control module 10 can provide synchronizing signal by the first voltage end V1 or the second voltage end V2 to backlight control module 40, therefore the non-inductive circuit part for controlling luminescence unit 30 luminescence (namely comprises the part of backlight control module 40 and switch module 50, and this part does not arrange afterflow inductance) be connected with flyback control module 10, no longer independently of one another.Therefore only need that once electrolytic filtering is carried out to the signal being about to input to light emitting module 30 and effectively can remove the high frequency noise being provided to this light emitting module 30 voltage.Therefore, structure is simpler in terms of existing technologies.Certainly, under the prerequisite not considering cost and circuit structure, in order to improve the above-mentioned high frequency noise of further more effective removal, multistage above-mentioned electrolysis filtering submodule 201 can be set in backlight drive circuit.Wherein, above-mentioned electrolysis filtering submodule 201 can comprise the first electric capacity Ca in parallel and the second electric capacity Cb.
In addition, light emitting module 30 comprises LED lamp bar, and switch module 50 comprises switching transistor M1.Wherein, this switching transistor M1 can be MOS (English full name: MetalOxidSemiconductor; Metal-oxide-the field effect of Chinese full name) transistor.The type of the present invention to switching transistor M1 does not limit, and can be N-type transistor, also can be P-type crystal pipe.Following examples are all the explanations carried out for N-type transistor.
When the closure of commutation diode VD1 is different, the connected mode of above-mentioned backlight drive circuit also can change.Be described in detail especially by following examples.
Embodiment one
In the present embodiment, flyback control module 10 provides malleation by the first voltage end V1 to light emitting module 30, and the oscillogram that this first voltage end V1 outputs signal as shown in Figure 5 b.
In the case, as shown in Figure 5 a, above-mentioned first loop the first terminal I's connected mode of backlight drive circuit is 1. connected with the anode of commutation diode VD1, and the negative electrode of commutation diode VD1 connects the anode of LED lamp bar.First pole of the negative electrode connecting valve transistor M1 of this LED lamp bar, second pole of switching transistor M1 and the first loop equal ground connection of the second terminal II 1., thus realize the electrical connection between switch module 50 and the first loop the second terminal II 1. by earth terminal.In addition, the grid of switching transistor M1 connects backlight control module 40.Concrete, this backlight control module 40 can comprise control chip N, and the grid of this switching transistor M1 can be connected with a pin of backlight control module 40 (such as pin DRV).
On this basis, one end of electrolysis filtering submodule 201 is connected with the anode of LED lamp bar, and the other end connects the negative electrode of LED lamp bar.
So, by being electrically connected between above-mentioned first voltage end V1, commutation diode VD1, LED lamp bar, switching transistor M1 and earth terminal, 1. above-mentioned first loop is closed.When switching transistor M1 conducting, the anode of LED lamp bar and negative electrode have height pressure reduction, thus generation current driving LED lamp bar is luminous.
Below, the backlight drive circuit shown in composition graphs 5a, is described in detail backlight drive process.
First, the transistor M2 in flyback control module 10 is in cut-off state, and the energy of transformer T enters the release stage.In the case, the first loop that this transformer T secondary coil can be set 1. with second servo loop coil lock number 2., make in the t2 moment as shown in Figure 5 b, 2. also non-conducting is (concrete for above-mentioned second servo loop, diode VD5 in main board power supply module 60 also non-conducting, this main board power supply module 60 is not also started working), and the first loop 1. in the preferential conducting of commutation diode VD1, make this flyback control module 10 can provide forward operating voltage by the first voltage end V1 to LED lamp bar.
Now, when the control chip N in backlight control module 40 can detect the voltage of the second voltage end V2 connected with transformer T-phase, and when the t2 moment provides high level by pin DRV to the grid of switching transistor M1, this switching transistor M1 conducting.When arriving t3 moment as shown in Figure 5 b, above-mentioned control chip N can detect LED lamp bar electric current by pin ISNS reach parameter preset (relevant with the dutycycle of pwm signal), and now switching transistor M1 ends, and LED lamp bar is not luminous.
In the t4-t1 stage, LED lamp bar is still not luminous, the transistor M2 conducting in flyback control module 10, and transformer T energy storage, the diode VD5 in main board power supply module 60 and commutation diode VD1 ends.And the mainboard that main board power supply module 60 can continue as display by storage capacitor C8 and C9 provides the voltage of 12V, until the transistor M2 in flyback control module 10 is in cut-off state again in the t2 moment of next cycle P.Ensuing control procedure can repeat above-mentioned cycle P.
In addition, in order to avoid the magnitude of voltage exported by above-mentioned first voltage end V1 is excessive, and adverse effect is caused to LED lamp bar.Above-mentioned backlight drive circuit can also comprise as shown in Figure 5 a and also comprise overvoltage protective module 70; connect the anode of LED lamp bar, the reference voltage end VSNS of backlight control module and earth terminal respectively; for under the control of earth terminal; voltage division processing is carried out to the voltage of the anode of LED lamp bar; to make when the magnitude of voltage after voltage division processing is greater than the magnitude of voltage of reference voltage end VSNS, this backlight control module 40 can gauge tap module 50 be closed.
Concrete; above-mentioned reference voltage end VSNS can be set to 1V; overvoltage protective module 70 can gather the voltage of the anode of LED lamp bar; and voltage division processing is carried out to it; when the voltage after voltage division processing is greater than 1V, illustrate that the malleation magnitude of voltage being provided to LED lamp bar from above-mentioned first voltage end V1 is excessive.In the case, backlight control module 40 can provide low level by control chip N to the grid of switching transistor M1, and this switching transistor M1 place is ended, and LED lamp bar is closed, thus the phenomenon avoiding excessive operating voltage to cause LED lamp bar to be burnt occurs.
Wherein, above-mentioned overvoltage protective module 70 can comprise the first resistance R1, the second resistance R2, the 3rd resistance R.
The input end of the first resistance R1 connects the anode of LED lamp bar, and the second resistance R2 output terminal is connected reference voltage end VSNS with the input end of the 3rd resistance R3, and the output terminal of the 3rd resistance connects earth terminal.Certainly above-mentioned is only illustrating overvoltage protective module 70.This is no longer going to repeat them for the overvoltage protective module 70 of other structure, but all belong to protection scope of the present invention.
Embodiment two
In the present embodiment, flyback control module 10 provides negative pressure by the first voltage end V1 to light emitting module 30, and the oscillogram that this first voltage end V1 outputs signal as shown in Figure 6 b.
In the case, the connected mode of backlight drive circuit as shown in Figure 5 a, the first terminal I in the first loop 1. (as shown in Figure 4) is connected with the negative electrode of commutation diode VD1, and the anode of this commutation diode VD1 connects the anode of LED lamp bar, the plus earth of LED lamp bar.
In addition, first pole of switching transistor M1 connects the first loop the second terminal II 1., the second pole ground connection, and grid connects backlight control module 40.Concrete, the grid of switching transistor M1 can be connected with a pin of backlight control module 40 (such as pin DRV).
On this basis, one end of electrolysis filtering submodule 201 is connected with the negative electrode of LED lamp bar, other end ground connection.
As shown in Figure 6 a, due to the negative electrode of LED lamp bar and the second extremely equal ground connection of switching transistor M1, therefore the negative electrode of LED lamp bar and second of switching transistor M1 extremely can be electrically connected by earth terminal.So, by being electrically connected between above-mentioned first voltage end V1, commutation diode VD1, LED lamp bar, switching transistor M1 and earth terminal, 1. above-mentioned first loop is closed.When switching transistor M1 conducting, the anode of LED lamp bar and negative electrode have height pressure reduction, thus generation current driving LED lamp bar is luminous.
Below, the backlight drive circuit shown in composition graphs 6a, is described in detail backlight drive process.
First, the transistor M2 in flyback control module 10 is in cut-off state, and the energy of transformer T enters the release stage.In the case, the first loop that this transformer T secondary coil can be set 1. with second servo loop coil lock number 2., make in the t2 moment as shown in Figure 6 b, 2. also non-conducting is (concrete for above-mentioned second servo loop, diode VD5 in main board power supply module 60 also non-conducting, this main board power supply module 60 is not also started working), and the first loop 1. in the preferential conducting of commutation diode VD1, make this flyback control module 10 can provide negative sense operating voltage by the first voltage end V1 to LED lamp bar.
Now, when the control chip N in backlight control module 40 can detect the voltage of the second voltage end V2 connected with transformer T-phase, and when the t2 moment provides high level by pin DRV to the grid of switching transistor M1, this switching transistor M1 conducting.When arriving t3 moment as shown in Figure 5 b, above-mentioned control chip N can detect LED lamp bar electric current by pin ISNS and reach parameter preset (relevant with the dutycycle of pwm signal), now switching transistor M1 ends, LED lamp bar is not luminous, but the negative electrode of LED lamp bar still can receive the negative sense operating voltage inputted by the first voltage end V1.
In the t4-t1 stage, LED lamp bar is still not luminous, the transistor M2 conducting in flyback control module 10, and transformer T energy storage, the diode VD5 in main board power supply module 60 and commutation diode VD1 ends.And the mainboard that main board power supply module 60 can continue as display by storage capacitor C8 and C9 provides the voltage of 12V, until the transistor M2 in flyback control module 10 is in cut-off state again in the t2 moment of next cycle P.Ensuing control procedure can repeat above-mentioned cycle P.
In sum, identical with the type of drive of the backlight drive circuit structure that Fig. 6 a provides for Fig. 5 a, all detected by the voltage of the control chip N in backlight control module 40 couple and transformer T-phase the second voltage end V2 even, and in the t2 moment by this switching transistor M1 conducting, make LED lamp bar luminous.And control chip N can be ended according to parameter preset (relevant with the dutycycle of pwm signal) gauge tap transistor M1 by pin ISNS, to close LED lamp bar.Difference is, in Fig. 5 a, flyback control module 10 provides malleation by the first voltage end V1 to the anode of LED lamp bar, and in Fig. 6 a, flyback control module 10 provides negative pressure by the first voltage end V1 to the negative electrode of LED lamp bar.
In addition, in order to avoid the magnitude of voltage exported by above-mentioned first voltage end V1 is excessive, and adverse effect is caused to LED lamp bar.Above-mentioned backlight drive circuit can also comprise as shown in Figure 5 b and also comprise under-voltage protective module 71; connect the negative electrode of LED lamp bar, reference voltage end VSNS, the tertiary voltage end VDD of backlight control module 30 and earth terminal respectively; for under the control of tertiary voltage end VDD and earth terminal; voltage division processing is carried out to the voltage of the negative electrode of LED lamp bar; to make when the magnitude of voltage after voltage division processing is less than the magnitude of voltage of reference voltage end VSNS, backlight control module 40 can gauge tap module 50 be closed.
Concrete; above-mentioned reference voltage end VSNS can be set to 0.2V; above-mentioned tertiary voltage VDD input high level; under-voltage protective module 71 can gather the voltage of the negative electrode of LED lamp bar; and voltage division processing is carried out to it; when the voltage after voltage division processing is less than 0.2V, illustrate that the negative pressure magnitude of voltage being provided to LED lamp bar from above-mentioned first voltage end V1 is excessive.In the case, backlight control module 40 can provide low level by control chip N to the grid of switching transistor M1, and this switching transistor M1 place is ended, and LED lamp bar is closed, thus the phenomenon avoiding excessive operating voltage to cause LED lamp bar to be burnt occurs.
Wherein, above-mentioned under-voltage protective module 71 can comprise the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the tenth resistance R10 and the 11 resistance R11.5th resistance R5, the 6th resistance R6, the 7th resistance R7 connect successively, and the input end of the 5th resistance R5 connects the negative electrode of LED lamp bar, the output head grounding of the 7th resistance R7.The input end of the 8th resistance R8 connects the output terminal of the 6th resistance R6, and the output terminal of the 8th resistance R8 is connected reference voltage end VSNS with the input end of the 9th resistance R9, and the output terminal of the 9th resistance R9 connects the output terminal of the tenth resistance R10.Tenth resistance R10 and the 11 resistance R11 connects, and the input end of the tenth resistance R10 connects tertiary voltage end VDD, the output head grounding of the 11 resistance R11.Certainly above-mentioned is only illustrating under-voltage protective module 71.This is no longer going to repeat them for the under-voltage protective module 71 of other structure, but all belong to protection scope of the present invention.
In the backlight drive module that following table provides the embodiment of the present invention, the model of each element such as resistance, electric capacity and diode is illustrated.The model parameter of certain the present invention to element is not limited thereto.
Concrete, in flyback control module 10, the model of each resistance is in table 1:
Table 1
| Resistance indicates | Resistance model |
| R20 | R818 |
| R21 | R995 |
| R22 | R995 |
| R23 | R994 |
| R24 | R866 |
| R25 | R809 |
| R26 | R808 |
| R27 | R849 |
| R28 | R844 |
| R29 | R835 |
| R30 | R847 |
| R31 | R819 |
| R32 | R817 |
In flyback control module 10, the model of each electric capacity is in table 2:
Table 2
| Electric capacity indicates | Electric capacity model |
| C1 | C843 |
| C2 | C842 |
| C3 | C845 |
| C4 | C958 |
| C5 | C954 |
| C6 | C955 |
In flyback control module 10, the model of diode is in table 3:
Table 3
| Diode indicates | Diode model |
| VD2 | VD812 |
| VD3 | VD813 |
| VD4 | VD822 |
The model of flyback control module 10 chips N1 is N801, and the model of chip N2 is N808.The model of transformer T is T801, and the model of transistor M2 is V801.
In main board power supply module 60, the model of each resistance is in table 4:
Table 4
| Resistance indicates | Resistance model |
| R33 | R851 |
| R34 | R861 |
| R35 | R860 |
| R36 | R858 |
| R37 | R856 |
In main board power supply module 60, the model of each electric capacity is in table 5:
Table 5
| Electric capacity indicates | Electric capacity model |
| C7 | C865 |
| C8 | C851 |
| C9 | C968 |
In main board power supply module 60, the model of inductance is L808, and the model of voltage stabilizer is N807.
The model of the resistance R38 in filter rectification module 20 is R855, and the model of commutation diode VD1 is VD931, and electric capacity Ca is C974, and electric capacity Cb is C973.
In light emitting module 30, the model of each LED etc. can be VD933, VD934 or VD935.
In backlight control module 40, the model of each resistance is in table 6:
Table 6
| Resistance indicates | Resistance model |
| R39 | R963 |
| R40 | R916 |
| R41 | R917 |
| R42 | R910 |
| R43 | R911 |
| R44 | R933 |
| R45 | R912 |
| R46 | R913 |
| R47 | R914 |
| R48 | R915 |
| R49 | R962 |
| R50 | R920 |
| R51 | R979 |
| R52 | R978 |
| R53 | R943 |
| R54 | R941 |
| R55 | R942 |
| R56 | R923 |
| R57 | R922 |
In backlight control module 40, the model of each electric capacity is in table 7:
Table 7
| Electric capacity indicates | Electric capacity model |
| C11 | C938 |
| C12 | C970 |
| C13 | C966 |
| C14 | C976 |
| C15 | C824 |
| C16 | C 932 |
| C17 | C 972 |
| C18 | C 930 |
In backlight control module 40, the model of control chip is N905.
The model of the switching transistor M1 in switch module 50 is V902.
In overvoltage protective module 70 as shown in Figure 5 a, the model of the first resistance R1, the second resistance R2, the 3rd resistance R3 is respectively R821, R815, R814.
Under-voltage protective module 71 can comprise the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the tenth resistance R10 and the 11 resistance R11 model be respectively R821, R815, R814, R813, R812, R810, R811.
The embodiment of the present invention provides a kind of display device, comprise any one backlight drive circuit as mentioned above, there is the structure identical with the backlight drive circuit that previous embodiment is supplied to and beneficial effect, because previous embodiment is described in detail the structure of backlight drive circuit and beneficial effect, repeat no more herein.
It should be noted that, in embodiments of the present invention, display device specifically can comprise liquid crystal indicator, and such as this display device can be any product or parts with Presentation Function such as liquid crystal display, LCD TV, digital album (digital photo frame), mobile phone or panel computer.
The embodiment of the present invention provides a kind of driving method of backlight drive circuit, for driving any one backlight drive circuit above-mentioned.As shown in Figure 7, described method comprises:
S101, flyback control module 10 provide synchronizing signal by the first voltage end V1 and the second voltage end V2 to backlight control module 40, and provide operating voltage by the first voltage end V1 to light emitting module 30.
Concrete, as shown in Figure 5 a, the transistor M2 in flyback control module 10 is in cut-off state, and the energy of transformer T enters the release stage.In the case, the first loop that this transformer T secondary coil can be set 1. with second servo loop coil lock number 2., make in the t2 moment as shown in Figure 5 b, 2. also non-conducting is (concrete for above-mentioned second servo loop, diode VD5 in main board power supply module 60 also non-conducting, this main board power supply module 60 is not also started working), and the first loop 1. in the preferential conducting of commutation diode VD1, make this flyback control module 10 can provide forward operating voltage by the first voltage end V1 to LED lamp bar.Or as shown in Figure 6 a, flyback control module 10 can provide negative sense operating voltage by the first voltage end V1 to LED lamp bar.
S102, backlight control module 40 are according to synchronizing signal opening switch module, and under the state that switch module 50 is opened, light emitting module 30 is luminous.
Concrete, when the control chip N in backlight control module 40 can detect the voltage with transformer T-phase the second voltage end V2 even, and t2 moment in such as Fig. 5 b or Fig. 6 b is when providing high level by pin DRV to the grid of switching transistor M1, this switching transistor M1 conducting, LED lamp bar is luminous.
S103, backlight control module 40 are according to parameter preset closing switch module 40, and light emitting module 30 is closed.
Concrete, when arriving the t3 moment as shown in Fig. 5 b or Fig. 6 b, the control chip N of above-mentioned backlight control module 40 can detect LED lamp bar electric current by pin ISNS and reach parameter preset, and now switching transistor M1 ends, and LED lamp bar is not luminous.
Wherein, the pulse width modulating signal that backlight control module 40 exports, its dutycycle is determined by above-mentioned parameter preset.Namely those skilled in the art can be arranged above-mentioned parameter preset according to actual needs, have reached the object regulating pwm signal dutycycle.
Afterwards, in such as t4-t1 stage shown in Fig. 5 b or Fig. 6 b, LED lamp bar is still not luminous.Transistor M2 conducting in flyback control module 10, transformer T energy storage, the diode VD5 in main board power supply module 60 and commutation diode VD1 ends.And the mainboard that main board power supply module 60 can continue as display by storage capacitor C8 and C9 provides the voltage of 12V, until the transistor M2 in flyback control module 10 is in cut-off state again in the t2 moment of next cycle P.Ensuing control procedure can repeat above-mentioned cycle P.
In sum, without the need to boosting or reduced pressure operation to the output voltage of flyback control module in above-mentioned driving process, therefore this driving method based on backlight drive circuit in without the need to arranging afterflow inductance.So, without the need to carrying out the conversion of boost in voltage or step-down between the voltage that the voltage of the first voltage end output of flyback control module and light emitting module receive, magnitude of voltage is equal, so can avoid the high energy consumption caused in voltage transitions process.In addition, due to without the need to arranging afterflow inductance, therefore circuit structure is simple, and cost is lower.
The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; change can be expected easily or replace, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of described claim.
Claims (11)
1. a backlight drive circuit, is characterized in that, comprises flyback control module, filter rectification module, light emitting module, backlight control module, switch module;
Described flyback control module provides voltage to the first voltage end and the second voltage end; The voltage of wherein said first voltage end is greater than the voltage of described second voltage end;
First voltage end and described light emitting module described in described filter rectification model calling, carry out filter rectification for the voltage exported described first voltage end, and export the voltage after filter rectification to described light emitting module;
Described backlight control module connects described first voltage end and described switch module, under the control of described first voltage end, triggers described backlight control module to described switch module output pulse width modulation signal; Or described backlight control module connects described second voltage end and described switch module, under the control of described second voltage end, triggers described backlight control module to described switch module output pulse width modulation signal;
Described switch module also connects described light emitting module, for conducting or cut-off under the control of described pulse width modulating signal, and under the state of conducting, drives described light emitting module luminous.
2. backlight drive circuit according to claim 1, is characterized in that, also comprises the main board power supply module connecting described second voltage end, for the signal according to described second voltage end, exports main board power supply voltage.
3. backlight drive circuit according to claim 1, is characterized in that, described flyback control module comprises transformer, and the secondary coil of described transformer has the first loop and second servo loop; The first terminal in described first loop is connected with described first voltage end, and the second terminal is electrically connected with described switch module; The first terminal of described second servo loop is connected with described second voltage end, the second terminal ground.
4. backlight drive circuit according to claim 3, is characterized in that, described filter rectification module comprises commutation diode and at least one-level electrolysis filtering submodule; Described light emitting module comprises LED lamp bar; Described switch module comprises switching transistor.
5. backlight drive circuit according to claim 4, it is characterized in that, the first terminal in described first loop is connected with the anode of described commutation diode, the negative electrode of described commutation diode connects the anode of described LED lamp bar, the negative electrode of described LED lamp bar connects the first pole of described switching transistor, second pole of described switching transistor and the equal ground connection of the second terminal in described first loop, the grid of described switching transistor connects described backlight control module;
One end of described electrolysis filtering submodule is connected with the anode of described LED lamp bar, and the other end connects the negative electrode of described LED lamp bar.
6. backlight drive circuit according to claim 4, it is characterized in that, the first terminal in described first loop is connected with the negative electrode of described commutation diode, and the anode of described commutation diode connects the anode of described LED lamp bar, the plus earth of described LED lamp bar; First pole of described switching transistor connects second terminal in described first loop, the second pole ground connection, and grid connects described backlight control module;
One end of described electrolysis filtering submodule is connected with the negative electrode of described LED lamp bar, other end ground connection.
7. backlight drive circuit according to claim 5; it is characterized in that; also comprise overvoltage protective module; connect the anode of described LED lamp bar, the reference voltage end of described backlight control module and earth terminal respectively; for under the control of described earth terminal; carry out voltage division processing to the voltage of the anode of described LED lamp bar, to make when the magnitude of voltage after voltage division processing is greater than the magnitude of voltage of described reference voltage end, described backlight control module can control described switch module and close.
8. backlight drive circuit according to claim 6; it is characterized in that; also comprise under-voltage protective module; connect the negative electrode of described LED lamp bar, the reference voltage end of described backlight control module, tertiary voltage end and earth terminal respectively; for under the control of described tertiary voltage end and described earth terminal; voltage division processing is carried out to the voltage of the negative electrode of described LED lamp bar; to make when the magnitude of voltage after voltage division processing is less than the magnitude of voltage of described reference voltage end, described backlight control module can control described switch module and close.
9. backlight drive circuit according to claim 4, is characterized in that, described electrolysis filtering submodule comprises the second electric capacity of the first electric capacity in parallel.
10. a display device, is characterized in that, comprises the backlight drive circuit as described in any one of claim 1-9.
11. 1 kinds for driving the method for the backlight drive circuit as described in any one of claim 1-9, is characterized in that, comprising:
Flyback control module provides synchronizing signal by the first voltage end and the second voltage end to backlight control module, and provides operating voltage by described first voltage end to light emitting module;
Described backlight control module is according to described synchronizing signal opening switch module, and under the state that described switch module is opened, described light emitting module is luminous;
Described backlight control module closes described switch module according to parameter preset, and described light emitting module is closed.
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Cited By (4)
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| CN110189712A (en) * | 2019-05-24 | 2019-08-30 | 北京星网锐捷网络技术有限公司 | A kind of drive circuit for backlight module group, display device and control method |
| CN111883071A (en) * | 2020-08-12 | 2020-11-03 | 深圳创维－Rgb电子有限公司 | Backlight compensation method and device, display equipment and readable storage medium |
| CN111883085A (en) * | 2020-09-28 | 2020-11-03 | 南京熊猫电子制造有限公司 | Device for improving stable work of liquid crystal equipment |
| CN113848386A (en) * | 2021-10-14 | 2021-12-28 | 中国南方电网有限责任公司超高压输电公司广州局 | Voltammeter and voltammeter control method |
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Application publication date: 20160316 |