CN102833912A - LED (light emitting diode) power circuit, backlight module and liquid crystal display device - Google Patents
LED (light emitting diode) power circuit, backlight module and liquid crystal display device Download PDFInfo
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- CN102833912A CN102833912A CN201210266460XA CN201210266460A CN102833912A CN 102833912 A CN102833912 A CN 102833912A CN 201210266460X A CN201210266460X A CN 201210266460XA CN 201210266460 A CN201210266460 A CN 201210266460A CN 102833912 A CN102833912 A CN 102833912A
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Abstract
The invention discloses an LED (light emitting diode) power circuit, a backlight module and a liquid crystal display device. The LED power circuit is characterized in that the two ends of a primary winding of a transformer are respectively connected with an anode output end and a cathode output end of a half-bridge resonant DC-DC control circuit; the two ends of a secondary winding of the transformer are respectively connected with the anodes of a group of LED strips by an LED rectifier and filter circuit; the cathode of each LED strip is connected with the input end of a current feedback circuit; the output end of the current feedback circuit is connected with the first input end of a voltage stabilizing feedback circuit; the second input end of the voltage stabilizing feedback circuit is connected with the feedback end of the LED rectifier and filter circuit; and the anode output end and the cathode output end of the voltage stabilizing feedback circuit are respectively connected with the anode feedback end and cathode feedback end of the half-bridge resonant DC-DC control circuit. The LED power circuit, the backlight module and the liquid crystal display device have the following beneficial effect: the capacitance balance method is creatively used, thus saving the DC-DC converters in the LED constant current control circuit and achieving the aims of saving energy and reducing cost.
Description
Technical field
The present invention relates to the LED technical field, specially refer to LED power circuit, module backlight and liquid crystal indicator.
Background technology
In existing LED power circuit, can the constant current steady operation for guaranteeing each LED lamp bar, adopting DC-DC change-over circuit and constant-current control circuit usually is the LED power supply.As shown in Figure 1, Fig. 1 is the electrical schematic diagram of LED power circuit in the prior art, to the bigger LED power supply of power output; After the AC supply voltage input, pass through EMI (Electromagnetic Interference, electromagnetic interference) filtering, high-voltage rectifying filtering, power calibration, half-bridge resonance topological transformation successively; The output direct current signal; This direct current signal passes through DC-DC change-over circuit and constant-current control circuit again, arrives each LED lamp bar at last, is the LED power supply.Because the conversion efficiency of DC-DC change-over circuit has only 90%, and costs an arm and a leg, and exists efficient low, the shortcoming that cost is high.Wherein the DC-DC circuit exists efficient to reduce, the shortcoming that cost rises.
Summary of the invention
Main purpose of the present invention is that a kind of efficient, energy-conservation, LED power circuit that cost is low, module backlight and liquid crystal indicator are provided.
The present invention proposes a kind of LED power circuit; Comprise AC-DC translation circuit, half-bridge resonance DC-DC control circuit, voltage stabilizing feedback circuit and at least two group LED lamp bars; The input of said AC-DC translation circuit connects the supply voltage output; The output of said AC-DC translation circuit connects the input of said half-bridge resonance DC-DC control circuit, also comprises transformer, current feedback circuit and two paths of LED current rectifying and wave filtering circuit at least;
The two ends of the elementary winding of said transformer connect the cathode output end and the cathode output end of said half-bridge resonance DC-DC control circuit respectively; The two ends of said Secondary winding of transformer connect the anode of one group of LED lamp bar respectively through a paths of LEDs current rectifying and wave filtering circuit; Each negative electrode of organizing LED lamp bar connects the input of said current feedback circuit; The output of said current feedback circuit connects the first input end of said voltage stabilizing feedback circuit; The feedback end of the paths of LEDs current rectifying and wave filtering circuit in second input of said voltage stabilizing feedback circuit and the said current rectifying and wave filtering circuit of two paths of LED at least is connected, and the cathode output end of said voltage stabilizing feedback circuit and cathode output end are connected the anodal feedback end and the negative pole feedback end of said half-bridge resonance DC-DC control circuit respectively.
Preferably; Said LED current rectifying and wave filtering circuit comprises series capacitance, diode and filter capacitor; One end of said Secondary winding of transformer connects the anode of said diode through said series capacitance; The negative electrode of said diode connects the anode of one group of LED lamp bar, and the negative electrode of said diode is also through said filter capacitor ground connection.
Preferably; Said voltage stabilizing feedback circuit comprises first resistance, second resistance, the 3rd resistance, pressurizer, optical coupler and first feedback capacity; The negative electrode of the diode of the paths of LEDs current rectifying and wave filtering circuit in the said current rectifying and wave filtering circuit of two paths of LED at least is through second resistance and the 3rd grounding through resistance, and the negative electrode of said diode also connects the anode of the light-emitting diode of said optical coupler through first resistance; The negative electrode of said light-emitting diode connects the negative electrode of said voltage-stabiliser tube, the plus earth of said voltage-stabiliser tube, and the adjustable end of said voltage-stabiliser tube is connected between the node of said second resistance and the 3rd resistance; Said first feedback capacity, one end connects the negative electrode of said voltage-stabiliser tube, and the said first feedback capacity other end is connected on the node between said second resistance and the 3rd resistance; The collector and emitter of the photistor of said optical coupler connects the anodal feedback end and the negative pole feedback end of said half-bridge resonance DC-DC control circuit respectively.
Preferably; Said current feedback circuit comprises the 4th resistance, the 5th resistance, the 6th resistance, second feedback capacity and triode; The said negative electrode of respectively organizing LED lamp bar is through said the 6th grounding through resistance; The base stage of said triode is connected on the said negative electrode and the node between said the 6th resistance of respectively organizing LED lamp bar through said the 4th resistance; The grounded emitter of said triode, said second feedback capacity and the 5th resistance are connected in parallel on respectively between the emitter and base stage of said triode, and the collector electrode of said triode connects the negative electrode of the Light-Emitting Diode of said optical coupler.
Preferably, said triode is the NPN triode.
Preferably; Said AC-DC translation circuit comprises electromagnetic interference EMI filter circuit, high-voltage rectifying filter circuit and power factor correction circuit; The input of said electromagnetic interference EMI filter circuit connects the supply voltage output; The output of said electromagnetic interference EMI filter circuit connects the input of said high-voltage rectifying filter circuit; The output of said high-voltage rectifying filter circuit connects the input of said power factor correction circuit, and the output of said power factor correction circuit connects the input of said half-bridge resonance DC-DC control circuit.
Preferably, said transformer is a plurality of, the head and the tail series connection successively of the elementary winding of each transformer.
Preferably, the equal turn numbers of the elementary winding of said each transformer, the equal turn numbers of said each Secondary winding of transformer.
The present invention also proposes a kind of module backlight; Comprise the LED power circuit; This LED power circuit comprises AC-DC translation circuit, half-bridge resonance DC-DC control circuit, voltage stabilizing feedback circuit and at least two group LED lamp bars; The input of AC-DC translation circuit connects the supply voltage output, and the output of AC-DC translation circuit connects the input of half-bridge resonance DC-DC control circuit, and this LED power circuit also comprises transformer, current feedback circuit and two paths of LED current rectifying and wave filtering circuit at least;
The two ends of the elementary winding of transformer connect the cathode output end and the cathode output end of half-bridge resonance DC-DC control circuit respectively; The two ends of Secondary winding of transformer connect the anode of one group of LED lamp bar respectively through a paths of LEDs current rectifying and wave filtering circuit; Each organizes the input of the negative electrode connection current feedback circuit of LED lamp bar; The output of current feedback circuit connects the first input end of voltage stabilizing feedback circuit; The feedback end of the paths of LEDs current rectifying and wave filtering circuit in second input of voltage stabilizing feedback circuit and the two paths of LED current rectifying and wave filtering circuit at least is connected, and the cathode output end of voltage stabilizing feedback circuit and cathode output end are connected the anodal feedback end and the negative pole feedback end of half-bridge resonance DC-DC control circuit respectively.
The present invention also proposes a kind of liquid crystal indicator; Comprise module backlight; This module backlight comprises the LED power circuit; This LED power circuit comprises AC-DC translation circuit, half-bridge resonance DC-DC control circuit, voltage stabilizing feedback circuit and at least two group LED lamp bars; The input of AC-DC translation circuit connects the supply voltage output, and the output of AC-DC translation circuit connects the input of half-bridge resonance DC-DC control circuit, and this LED power circuit also comprises transformer, current feedback circuit and two paths of LED current rectifying and wave filtering circuit at least;
The two ends of the elementary winding of transformer connect the cathode output end and the cathode output end of half-bridge resonance DC-DC control circuit respectively; The two ends of Secondary winding of transformer connect the anode of one group of LED lamp bar respectively through a paths of LEDs current rectifying and wave filtering circuit; Each organizes the input of the negative electrode connection current feedback circuit of LED lamp bar; The output of current feedback circuit connects the first input end of voltage stabilizing feedback circuit; The feedback end of the paths of LEDs current rectifying and wave filtering circuit in second input of voltage stabilizing feedback circuit and the two paths of LED current rectifying and wave filtering circuit at least is connected, and the cathode output end of voltage stabilizing feedback circuit and cathode output end are connected the anodal feedback end and the negative pole feedback end of half-bridge resonance DC-DC control circuit respectively.
The present invention is for the bigger LED power supply of power, and creativeness is used the electric capacity balancing method, saves DC-DC converter in the LED constant-current control circuit, reaches energy-conservation and the purpose cost-saving.
Description of drawings
Fig. 1 is the electrical schematic diagram of LED power circuit in the prior art;
Fig. 2 is the structural representation of LED power circuit in one embodiment of the invention;
Fig. 3 is the electrical schematic diagram of LED power circuit in another embodiment of the present invention.
The realization of the object of the invention, functional characteristics and advantage will combine embodiment, further specify with reference to accompanying drawing.
Embodiment
Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
As shown in Figure 2; Fig. 2 is the structural representation of LED power circuit in one embodiment of the invention; The LED power circuit that this embodiment mentions; Comprise AC-DC translation circuit 10, half-bridge resonance DC-DC control circuit 20, voltage stabilizing feedback circuit 30, current feedback circuit 40, transformer 50, two paths of LED current rectifying and wave filtering circuit 60 and at least two group LED lamp bars 70 at least; The input of AC-DC translation circuit 10 connects the supply voltage output; The output of AC-DC translation circuit 10 connects the input of half-bridge resonance DC-DC control circuit 20; The two ends of the elementary winding of transformer 50 connect the cathode output end and the cathode output end of half-bridge resonance DC-DC control circuit 20 respectively; The two ends of the secondary winding of transformer 50 connect the anode of one group of LED lamp bar 70 respectively through a paths of LEDs current rectifying and wave filtering circuit 60, each organizes the input of the negative electrode connection current feedback circuit 40 of LED lamp bar 70, and the output of current feedback circuit 40 connects the first input end of voltage stabilizing feedback circuit 30; The feedback end of the paths of LEDs current rectifying and wave filtering circuit 60 in second input of voltage stabilizing feedback circuit 30 and the two paths of LED current rectifying and wave filtering circuit at least is connected, and the cathode output end of voltage stabilizing feedback circuit 30 and cathode output end are connected the anodal feedback end and the negative pole feedback end of half-bridge resonance DC-DC control circuit 20 respectively.
Present embodiment is according to the half-bridge topology operation principle; The secondary winding work positive-negative half-cycle of transformer 50; When the positive half cycle of the secondary winding of transformer 50 is worked; The first paths of LEDs current rectifying and wave filtering circuit, 61 conductings that are connected with transformer 50 1 ends, the 71 output power supplies of 20 pairs first group LED lamp bar of half-bridge resonance DC-DC control circuit; Otherwise; When the secondary winding negative half period of transformer 50 is worked, the second paths of LEDs current rectifying and wave filtering circuit, 62 conductings that are connected with transformer 50 other ends, the 72 output power supplies of 20 pairs second group LED lamp bar of half-bridge resonance DC-DC control circuit; Two groups of LED lamp bars 70 obtain identical AC wave shape; It is approximate identical that rectification obtains effective value, and two road electric currents are similar, guarantees respectively to organize the 70 current balance type work of LED lamp bar.When LED lamp bar 70 because of other reason electrorheological when big; The electric current that current feedback circuit 40 feeds back to voltage stabilizing feedback circuit 30 increases; And then the electric current that voltage stabilizing feedback circuit 30 feeds back to half-bridge resonance DC-DC control circuit 20 increases, and the electric current that 20 controls of half-bridge resonance DC-DC control circuit output to transformer 50 elementary windings reduces, and the voltage at transformer 50 secondary winding two ends descends; Output to the electric current of respectively organizing LED lamp bar 70 and reduce, thereby guarantee respectively to organize LED lamp bar 70 constant current steady operations.
As shown in Figure 3, Fig. 3 is the electrical schematic diagram of LED power circuit in another embodiment of the present invention.
AC-DC translation circuit 10 comprises electromagnetic interference EMI filter circuit 11, high-voltage rectifying filter circuit 12 and power factor correction circuit 13; The input of electromagnetic interference EMI filter circuit 11 connects the supply voltage output; The output of electromagnetic interference EMI filter circuit 11 connects the input of high-voltage rectifying filter circuit 12; The output of high-voltage rectifying filter circuit 12 connects the input of power factor correction circuit 13, and the output of power factor correction circuit 13 connects the input of half-bridge resonance DC-DC control circuit 20.
Present embodiment adopts three transformer T1 ~ T3; The head and the tail series connection successively of the elementary winding of each transformer T1 ~ T3; It is the cathode output end that the different name end of the elementary winding of T1 connects half-bridge resonance DC-DC control circuit 20; The end of the same name of the elementary winding of T1 connects the different name end of the elementary winding of T2, and the end of the same name of the elementary winding of T2 connects the different name end of the elementary winding of T3, and the end of the same name of the elementary winding of T3 connects the cathode output end of half-bridge resonance DC-DC control circuit 20.The two ends of the secondary winding of each transformer T1 ~ T3 connect a paths of LEDs current rectifying and wave filtering circuit respectively, then comprise six paths of LEDs current rectifying and wave filtering circuits altogether, comprise series capacitance C1 ~ C6, diode D1 ~ D6 and filter capacitor C7 ~ C12.
Present embodiment is an example with transformer T1, and the first paths of LEDs current rectifying and wave filtering circuit comprises series capacitance C1, diode D1 and filter capacitor C7, and first group of LED lamp bar comprises the LED lamp LED1a ~ LEDna of head and the tail series connection successively; The second paths of LEDs current rectifying and wave filtering circuit comprises series capacitance C2, diode D2 and filter capacitor C8, and second group of LED lamp bar comprises the LED lamp LED1b ~ LEDnb of head and the tail series connection successively.The different name end of the secondary winding of transformer T1 is through the anode of series capacitance C1 connection diode D1, and the negative electrode of diode D1 connects the anode of first LED lamp LED1a in first group of LED lamp bar, and the negative electrode of diode D1 is also through filter capacitor C7 ground connection; The end of the same name of the secondary winding of transformer T1 is through the anode of series capacitance C2 connection diode D2, and the negative electrode of diode D2 connects the anode of first LED lamp LED1b in second group of LED lamp bar, and the negative electrode of diode D2 is also through filter capacitor C7 ground connection.
Voltage stabilizing feedback circuit 30 comprises first resistance R 1, second resistance R 2, the 3rd resistance R 3, pressurizer Q1, optical coupler OT01 and the first feedback capacity C13; The negative electrode of diode D1 is through second resistance R 2 and the 3rd resistance R 3 ground connection in the first paths of LEDs current rectifying and wave filtering circuit, and the negative electrode of diode D1 also connects the anode of the light-emitting diode of optical coupler OT01 through first resistance R 1; The negative electrode of the light-emitting diode of optical coupler OT01 connects the negative electrode of voltage-stabiliser tube Q1, the plus earth of voltage-stabiliser tube Q1, and the adjustable end of voltage-stabiliser tube Q1 is connected between the node of second resistance R 2 and the 3rd resistance R 3; The first feedback capacity C13, one end connects the negative electrode of voltage-stabiliser tube Q1, and the other end is connected on the node between second resistance R 2 and the 3rd resistance R 3; The collector and emitter of the photistor of optical coupler OT01 connects the anodal feedback end and the negative pole feedback end of half-bridge resonance DC-DC control circuit 20 respectively.
In the present embodiment; After the input of power supply alternating voltage; After electromagnetic interference EMI filtering, high-voltage rectifying filtering, power factor (PF) calibration; Output to three identical transformer T1 of parameter, T2, T3 through half-bridge resonance DC-DC control circuit 20, the elementary windings in series of transformer T1, T2, T3 is formed main power transformer, and the secondary winding output circuit framework of three transformer T1, T2, T3 is identical.The secondary winding one termination C1 of T1, D1, C7 give each the LED lamp LED1a ~ LEDna power supply of connecting in first group of LED lamp bar, and another termination of the secondary winding of T1 C2, D2, C8 give each the LED lamp LED1b ~ LEDnb power supply of connecting in second group of LED lamp bar; The connected mode of the secondary winding of transformer T2 and T3 is identical with T1.After each organizes the parallel connection of LED lamp bar,, carry out current detecting through the 6th resistance R 6 ground connection.When energising work, because C1 ~ C6 parameter is identical, each number of organizing the LED lamp of connecting in the LED lamp bar is identical; According to LED operating current parameter designing; Connect required operating voltage of LED requires also identically, and the operating voltage of LED lamp bar is controlled with R3 sampling, OT01 feedback and Q1 voltage stabilizing through R2, feeds back to half-bridge resonance DC-DC control circuit 20; Make the stable driving voltage of half-bridge resonance DC-DC control circuit 20 outputs, keep the operate as normal of LED lamp bar.
Present embodiment is again example with T1; According to the half-bridge topology operation principle, the transformer secondary output winding work period is positive and negative each half cycle, when T1 is operated in positive half cycle; C1, D1 conducting, half-bridge resonance DC-DC control circuit 20 are that the LED lamp LED1a ~ LEDna of first group of LED lamp bar exports power supply; Otherwise, when T1 is operated in negative half period, C2, D2 conducting, half-bridge resonance DC-DC control circuit 20 is that the LED lamp LED1b ~ LEDnb of second group of LED lamp bar exports power supply.According to the capacitive balance principle, because electric capacity has at a distance from straight effect, two groups of LED lamp bars that are obtain identical AC wave shape, and it is approximate identical that rectification obtains effective value, guaranteed that two groups of LED lamp bar electric currents are similar.Simultaneously, owing to T1, T2, the elementary series connection of T3, power output is identical; And the equal turn numbers of the elementary winding of each transformer T1 ~ T3, the equal turn numbers of the secondary winding of each transformer T1 ~ T3 is according to the transformer inductance principle; Learn that first/secondary current is inversely proportional to than with the coil windings number of turn; Because three transformer T1 ~ T3 parameters are identical, the electric current of the secondary winding output of three transformer T1 ~ T3 is also identical, guarantees respectively to organize the work of LED lamp bar current balance type.
In addition; When LED lamp bar caused electrorheological big because of other reason, the voltage at the 6th resistance R 6 two ends also increased, and triode Q2 increases conducting because of base current; Thereby the light-emitting diode brightness strengthens among the optical coupler OT01; The electric current that feeds back in the photistor in the half-bridge resonance DC-DC control circuit 20 increases, and the primary winding current that 20 controls of half-bridge resonance DC-DC control circuit output to transformer T1 ~ T3 reduces, and the voltage at the secondary winding two ends of transformer T1 ~ T3 descends; Output to the electric current of respectively organizing LED lamp bar and reduce, thereby guarantee respectively to organize LED lamp bar constant current steady operation.Present embodiment is for the bigger LED power supply of power, and creativeness is used the electric capacity balancing method, saves DC-DC converter in the LED constant-current control circuit, reaches energy-conservation and the purpose cost-saving.
The present invention also proposes a kind of module backlight; Comprise the LED power circuit; This LED power circuit comprises AC-DC translation circuit, half-bridge resonance DC-DC control circuit, voltage stabilizing feedback circuit and at least two group LED lamp bars; The input of AC-DC translation circuit connects the supply voltage output, and the output of AC-DC translation circuit connects the input of half-bridge resonance DC-DC control circuit, and this LED power circuit also comprises transformer, current feedback circuit and two paths of LED current rectifying and wave filtering circuit at least;
The two ends of the elementary winding of transformer connect the cathode output end and the cathode output end of half-bridge resonance DC-DC control circuit respectively; The two ends of Secondary winding of transformer connect the anode of one group of LED lamp bar respectively through a paths of LEDs current rectifying and wave filtering circuit; Each organizes the input of the negative electrode connection current feedback circuit of LED lamp bar; The output of current feedback circuit connects the first input end of voltage stabilizing feedback circuit; The feedback end of the paths of LEDs current rectifying and wave filtering circuit in second input of voltage stabilizing feedback circuit and the two paths of LED current rectifying and wave filtering circuit at least is connected, and the cathode output end of voltage stabilizing feedback circuit and cathode output end are connected the anodal feedback end and the negative pole feedback end of half-bridge resonance DC-DC control circuit respectively.
The LED power circuit that module backlight of the present invention comprises can comprise all technical schemes among earlier figures 2 and Fig. 3 embodiment, and its detailed structure can be with reference to previous embodiment, does not do at this and gives unnecessary details.Owing to adopt aforementioned LED power circuit scheme, module backlight of the present invention is for existing module backlight, and creativeness is used the electric capacity balancing method, saves DC-DC converter in the LED constant-current control circuit, reaches energy-conservation and the purpose cost-saving.
The present invention also proposes a kind of liquid crystal indicator; Comprise module backlight; This module backlight comprises the LED power circuit; This LED power circuit comprises AC-DC translation circuit, half-bridge resonance DC-DC control circuit, voltage stabilizing feedback circuit and at least two group LED lamp bars; The input of AC-DC translation circuit connects the supply voltage output, and the output of AC-DC translation circuit connects the input of half-bridge resonance DC-DC control circuit, and this LED power circuit also comprises transformer, current feedback circuit and two paths of LED current rectifying and wave filtering circuit at least;
The two ends of the elementary winding of transformer connect the cathode output end and the cathode output end of half-bridge resonance DC-DC control circuit respectively; The two ends of Secondary winding of transformer connect the anode of one group of LED lamp bar respectively through a paths of LEDs current rectifying and wave filtering circuit; Each organizes the input of the negative electrode connection current feedback circuit of LED lamp bar; The output of current feedback circuit connects the first input end of voltage stabilizing feedback circuit; The feedback end of the paths of LEDs current rectifying and wave filtering circuit in second input of voltage stabilizing feedback circuit and the two paths of LED current rectifying and wave filtering circuit at least is connected, and the cathode output end of voltage stabilizing feedback circuit and cathode output end are connected the anodal feedback end and the negative pole feedback end of half-bridge resonance DC-DC control circuit respectively.
Liquid crystal indicator of the present invention comprises module backlight, and the LED power circuit that this module backlight comprises can comprise all technical schemes among earlier figures 2 and Fig. 3 embodiment, and its detailed structure can be with reference to previous embodiment, does not do at this and gives unnecessary details.Owing to adopt aforementioned LED power circuit scheme, liquid crystal indicator of the present invention is for existing liquid crystal indicator, and creativeness is used the electric capacity balancing method, saves DC-DC converter in the LED constant-current control circuit, reaches energy-conservation and the purpose cost-saving.
The above is merely the preferred embodiments of the present invention; Be not so limit claim of the present invention; Every equivalent structure or equivalent flow process conversion that utilizes specification of the present invention and accompanying drawing content to be done; Or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the present invention.
Claims (10)
1. LED power circuit; Comprise AC-DC translation circuit, half-bridge resonance DC-DC control circuit, voltage stabilizing feedback circuit and at least two group LED lamp bars; The input of said AC-DC translation circuit connects the supply voltage output; The output of said AC-DC translation circuit connects the input of said half-bridge resonance DC-DC control circuit, it is characterized in that, also comprises transformer, current feedback circuit and two paths of LED current rectifying and wave filtering circuit at least;
The two ends of the elementary winding of said transformer connect the cathode output end and the cathode output end of said half-bridge resonance DC-DC control circuit respectively; The two ends of said Secondary winding of transformer connect the anode of one group of LED lamp bar respectively through a paths of LEDs current rectifying and wave filtering circuit; Each negative electrode of organizing LED lamp bar connects the input of said current feedback circuit; The output of said current feedback circuit connects the first input end of said voltage stabilizing feedback circuit; The feedback end of the paths of LEDs current rectifying and wave filtering circuit in second input of said voltage stabilizing feedback circuit and the said current rectifying and wave filtering circuit of two paths of LED at least is connected, and the cathode output end of said voltage stabilizing feedback circuit and cathode output end are connected the anodal feedback end and the negative pole feedback end of said half-bridge resonance DC-DC control circuit respectively.
2. LED power circuit according to claim 1; It is characterized in that; Said LED current rectifying and wave filtering circuit comprises series capacitance, diode and filter capacitor; One end of said Secondary winding of transformer connects the anode of said diode through said series capacitance, and the negative electrode of said diode connects the anode of one group of LED lamp bar, and the negative electrode of said diode is also through said filter capacitor ground connection.
3. LED power circuit according to claim 2; It is characterized in that; Said voltage stabilizing feedback circuit comprises first resistance, second resistance, the 3rd resistance, pressurizer, optical coupler and first feedback capacity; The negative electrode of the diode of the paths of LEDs current rectifying and wave filtering circuit in the said current rectifying and wave filtering circuit of two paths of LED at least is through second resistance and the 3rd grounding through resistance, and the negative electrode of said diode also connects the anode of the light-emitting diode of said optical coupler through first resistance; The negative electrode of said light-emitting diode connects the negative electrode of said voltage-stabiliser tube, the plus earth of said voltage-stabiliser tube, and the adjustable end of said voltage-stabiliser tube is connected between the node of said second resistance and the 3rd resistance; Said first feedback capacity, one end connects the negative electrode of said voltage-stabiliser tube, and the said first feedback capacity other end is connected on the node between said second resistance and the 3rd resistance; The collector and emitter of the photistor of said optical coupler connects the anodal feedback end and the negative pole feedback end of said half-bridge resonance DC-DC control circuit respectively.
4. LED power circuit according to claim 3; It is characterized in that; Said current feedback circuit comprises the 4th resistance, the 5th resistance, the 6th resistance, second feedback capacity and triode; The said negative electrode of respectively organizing LED lamp bar is through said the 6th grounding through resistance, and the base stage of said triode is connected on the said negative electrode and the node between said the 6th resistance of respectively organizing LED lamp bar through said the 4th resistance, the grounded emitter of said triode; Said second feedback capacity and the 5th resistance are connected in parallel on respectively between the emitter and base stage of said triode, and the collector electrode of said triode connects the negative electrode of the Light-Emitting Diode of said optical coupler.
5. LED power circuit according to claim 4 is characterized in that, said triode is the NPN triode.
6. LED power circuit according to claim 4; It is characterized in that; Said AC-DC translation circuit comprises electromagnetic interference EMI filter circuit, high-voltage rectifying filter circuit and power factor correction circuit; The input of said electromagnetic interference EMI filter circuit connects the supply voltage output; The output of said electromagnetic interference EMI filter circuit connects the input of said high-voltage rectifying filter circuit, and the output of said high-voltage rectifying filter circuit connects the input of said power factor correction circuit, and the output of said power factor correction circuit connects the input of said half-bridge resonance DC-DC control circuit.
7. according to each described LED power circuit of claim 1 to 6, it is characterized in that said transformer is a plurality of, the head and the tail series connection successively of the elementary winding of each transformer.
8. LED power circuit according to claim 7 is characterized in that, the equal turn numbers of the elementary winding of each transformer, the equal turn numbers of said each Secondary winding of transformer.
9. a module backlight is characterized in that, comprises like each described LED power circuit of claim 1 to 8.
10. a liquid crystal indicator is characterized in that, comprises module backlight as claimed in claim 9.
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| US10271392B2 (en) | 2017-05-16 | 2019-04-23 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | LLC backlight driving control circuit |
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| US11783788B2 (en) | 2020-03-18 | 2023-10-10 | Hisense Visual Technology Co., Ltd. | Display apparatus and display control method |
| US11825577B2 (en) | 2020-08-24 | 2023-11-21 | Hisense Visual Technology Co., Ltd. | Display apparatus and step power circuit |
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Application publication date: 20121219 |