CN202696963U - Power supply control circuit, backlight module and liquid crystal display device - Google Patents
Power supply control circuit, backlight module and liquid crystal display device Download PDFInfo
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- CN202696963U CN202696963U CN 201220278915 CN201220278915U CN202696963U CN 202696963 U CN202696963 U CN 202696963U CN 201220278915 CN201220278915 CN 201220278915 CN 201220278915 U CN201220278915 U CN 201220278915U CN 202696963 U CN202696963 U CN 202696963U
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Abstract
The utility model relates to the technical field of liquid crystal display and provides a power supply control circuit, a backlight module and a liquid crystal display device. The circuit comprises an AC (Alternate Current) input unit, a rectifier bridge, a single-stage control unit, a diode, a LC (Inductance-Capacitance) oscillating circuit, a LED (Light-Emitting Diode) lamp bar, a LED current sampling resistor and a secondary feedback signal unit, wherein the AC input unit, the rectifier bridge and the single-stage control unit are arranged at the AC side of a transformer; the diode, the LC oscillating circuit, the LED lamp bar, the LED current sampling resistor and the secondary feedback signal unit are arranged at the DC side of the transformer; the AC input unit, the rectifier bridge and the single-stage control unit are sequentially connected in series; the diode, the LC oscillating circuit, the LED lamp bar, the LED current sampling resistor and the secondary feedback signal unit are connected; and the secondary feedback signal unit is connected to the single-stage PFC (Power Factor Correction) control unit to provide a secondary feedback signal to the single-stage PFC control unit. According to the utility model, the single-stage PFC control unit is adopted to directly control a secondary output current and a secondary output voltage; a primary PFC control unit, a LLC (Logical Link Control) control unit and primary large electrolysis are saved; the control complexity of the circuit is reduced; and the stability and the reliability are improved.
Description
Technical field
The utility model relates to technical field of liquid crystal display, particularly a kind of power control circuit, backlight module and liquid crystal display device.
Background technology
According to the national standard of electrical equipment energy consumption, for the equipment that uses power greater than 75 watts, need to when the power panel design of carrying out equipment, consider the impact of harmonic current and power factor, like this too for liquid crystal display device.Therefore, the backlight power panel of common light-emitting diode display spare is divided into two-stage usually in the prior art, Fig. 1 has showed the primary structure of prior art power panel, wherein, need to increase PFC(Power Factor Correction in primary side, power factor correction) control unit (generally comprising PFC inductance and PFC control chip), need to increase Opportunity awaiting control for linear unit and these two controlled cells of LLC control unit in primary side, standby power is responsible for exporting in the Opportunity awaiting control for linear unit, generally is output as 5V or 12V; The LLC control unit carries out the power resonance conversion, and output LED exports needed voltage, and follow-up LED control unit is realized constant current control to LED lamp bar.
In realizing the utility model process, inventor's discovery, the power panel of prior art needs a plurality of control unit collaborative works owing to adopting two-stage control, its control mode complexity, equipment cost is high; In addition, because element is more, the circuit damaged probability is larger, and its labyrinth causes again circuit maintainable poor.
The utility model content
The technical problem that (one) will solve
For above-mentioned shortcoming, the utility model provides a kind of power control circuit, backlight module and liquid crystal display device in order to solve the complicated unmanageable problem of LED-backlit power panel circuit in the prior art.
(2) technical scheme
In order to solve the problems of the technologies described above, on the one hand, the utility model provides a kind of power control circuit, described circuit comprises AC input cell, rectifier bridge and the single-stage control unit that is arranged at the transformer alternating side, and the diode, LC oscillating circuit, LED lamp bar, LED current sampling resistor and the secondary feedback signal unit that are arranged at the transformer dc side; Wherein, described AC input cell, rectifier bridge and single-stage control unit are connected successively, described diode, LC oscillating circuit, LED lamp bar, LED current sampling resistor and secondary feedback signal unit, described secondary feedback signal unit is connected to described single-stage PFC control unit, provides secondary feedback signal to described single-stage PFC control unit.
On the other hand, the utility model also provides a kind of backlight module simultaneously, comprises aforesaid power control circuit in the described backlight module.
On the one hand, the utility model also provides a kind of liquid crystal display device simultaneously again, and described liquid crystal display device comprises aforesaid backlight module.
(3) beneficial effect
In the technical solution of the utility model, directly control secondary output current and voltage owing to adopting single-stage PFC control unit, can realize the constant current control of LED, thereby elementary PFC control unit, LLC control unit and elementary large electrolysis have been saved than conventional architectures, thereby reduced the control complexity of circuit, saved equipment cost, and improved stability and the reliability of circuit, do not made equipment fragile and be convenient to safeguard.
Description of drawings
Fig. 1 is the power panel structural representation of backlight in the prior art;
Fig. 2 is the structural representation of the power panel of backlight among the embodiment of the present utility model;
Fig. 3 is the electrical block diagram of power control circuit among the embodiment of the present utility model;
Fig. 4 is the circuit connection diagram of PFC chip ZCD pin in the power control circuit in the preferred embodiment of the present utility model;
Fig. 5 is the electrical block diagram of power control circuit in another preferred embodiment of the present utility model;
Fig. 6 is the electrical block diagram of power control circuit in another preferred embodiment of the present utility model;
Fig. 7 is the electrical block diagram of considering the power control circuit of ground wire wiring in another preferred embodiment of the present utility model.
Embodiment
Below in conjunction with the accompanying drawing among the utility model embodiment, the technical scheme among the utility model embodiment is clearly and completely described, obviously, described embodiment is a part of embodiment of the present utility model, rather than whole embodiment.Based on the embodiment in the utility model, the every other embodiment that those of ordinary skills obtain under the prerequisite of not making creative work belongs to the scope that the utility model is protected.
In embodiment of the present utility model, adopt single-stage PFC control unit directly to control secondary output current and voltage, realize the constant current control of LED.Particularly, traditional PFC control unit is arranged between rectifier bridge and the elementary large electrochemical capacitor, further control by the LLC control unit secondary, and embodiment of the present utility model as shown in Figure 2, make interchange input current and input voltage for the sine wave with the frequency homophase at secondary use single-stage PFC control unit, saved elementary PFC control unit, LLC control unit and elementary large electrolysis than conventional architectures.
Again further referring to Fig. 3, the concrete structure of the LED-backlit source current control circuit among the embodiment of the present utility model comprises: be arranged at AC input cell L820, rectifier bridge VB7 and the single-stage PFC control unit of transformer T801 AC, and the diode VD818, LC oscillating circuit, LED lamp bar, LED current sampling resistor and the secondary feedback signal unit that are arranged at transformer T801 DC side; Wherein single-stage PFC control unit receives secondary feedback signal and controls electric current and the voltage that exchanges input.
Described transformer alternating side also is connected with the sampling resistor in parallel with described single-stage PFC control unit, and described sampling resistor is connected to described transformer by metal-oxide-semiconductor; Wherein, grid, CS pin and the GND pin that the Dri pin of described single-stage PFC control unit connects described metal-oxide-semiconductor connects respectively the two ends of described sampling resistor, and the source electrode of described metal-oxide-semiconductor connects described transformer, drain electrode and substrate and is connected and connects described sampling resistor; Also be parallel with a voltage stabilizing didoe between the source-drain electrode of described metal-oxide-semiconductor.
Below only be that the integral body of execution mode of the present utility model is described, this execution mode has reduced equipment cost and the complexity of power circuit, so that circuit control more easily realizes, but this execution mode still has further improved space, comes execution mode of the present utility model is described further below in conjunction with the preferred embodiment in each accompanying drawing.
Embodiment for Fig. 3, because single-stage PFC control unit also is to adopt common PFC chip to realize, and the embodiment of Fig. 3 has not had large electrolysis in primary side, during start, power-on impact current is very large (by the sampling analysis to circuit, the rush of current of the metal-oxide-semiconductor of the PFC of booting moment has surpassed 20A), excessive impulse current is very easy to cause damage to electronic component.
Utility model people continues to analyze the start shock problem from principle, find that major part all is the ZCD(ZERO CURRENT DETECTION of PFC chip, zero current detection) pin causes, because the ZCD pin signal of PFC chip all is voltage signal, interference a little will cause very large electric current and due to voltage spikes.Therefore among the preferred embodiment 1 of the utility model the voltage signal of ZCD is changed over current signal, thereby solved the current impact of booting moment.
The circuit of ZCD pin connects as shown in Figure 4 in this preferred embodiment 1, and wherein ZCD pin (C point) connects the collector electrode of the second triode Q2 and the 3rd triode Q3, the grounded emitter of the second triode Q2 and the 3rd triode Q3 simultaneously; The collector electrode of the 3rd triode Q3 connects the VCC pin by resistance R 44 and connects simultaneously the base stage of the 4th triode Q4 by capacitor C 41, the collector electrode of described the 4th triode Q4 is connected with the base stage (B point) of described the second triode, grounded emitter, and also is parallel with resistance R 45 between the base stage of described the 4th triode Q4 and the emitter; The base stage of the second triode Q2 connects the VCC pin by resistance R 43 and is connected with the collector electrode of the first triode Q1 simultaneously, and the grounded emitter of described the first triode Q1, base stage are connected with voltage input end A point through after the resistance R 41.The present embodiment is adjusted the voltage in the circuit by a plurality of triodes, so that the signal phase that DRI signal and A are ordered in the circuit is fully opposite, thereby the voltage signal that A is ordered is become current signal, improved the antijamming capability of circuit, again because the ZCD signal that C is ordered is basically identical with the A point, just postponed a little some time (be to be determined by the size of capacitor C 1 and R5 time of delay), effectively having eliminated the start in the circuit by this preferred implementation impacts (by the sampling analysis to circuit, the maximum impact electric current of booting moment is reduced to 4.6A, has greatly reduced the infringement of rush of current to element).
In addition, in the embodiment of the utility model Fig. 3, because the input voltage range of alternating current is wider, transformer usually can not be saturated, but in the situation that voltage ratio is higher, such as the moment of switching on and shutting down, transformer is very easily saturated again, if be easy to cause the damage of device after therefore using for a long time the switching on and shutting down number of times more, circuit reliability reduces.
For solving the saturated problem of transformer under the high pressure, in preferred embodiment of the utility model in circuit the resistance R 2 of three series connection of access in parallel, R3 and R4, as shown in Figure 5, in described transformer alternating side, be connected to the first resistance R 1 between the CS pin of described sampling resistor and described single-stage PFC control unit, be connected to second resistance R 2 in parallel with described sampling resistor and the first resistance R 1 between the CS pin of described single-stage PFC control unit and GND pin, the CS pin of described single-stage PFC control unit is connected to the 3rd resistance R 3 and the 4th resistance R 4 of connecting with the output of described rectifier bridge, described the 3rd resistance R 3 and the 4th resistance R 4 and described transformers connected in parallel.When voltage ratio is higher, voltage on the R3 is just higher, voltage on the corresponding R2 is also higher, because being expressed as the CS point voltage of the voltage sum on the upper voltage of R2 and the R1 is chip set point (namely this point voltage is fixed), therefore when the upper voltage of R2 increases, the upper voltage of R1 will reduce, thereby by the electric current of sampling resistor in just can limiting transformer, has solved the saturated problem of high pressure; And the preferred embodiment is in the situation that low pressure is complete in impact on system works.
By the sampling analysis to circuit, the electric current of booting moment generally is limited at about 4A, has realized the current limliting to transformer, has greatly reduced the infringement of starup current to device; In addition, because electric current reduces, the size of transformer also can correspondingly reduce, and has realized the miniaturization of device.
In the embodiment of the utility model Fig. 3, in wide-voltage range, if so that the loading of stable output, load and unloading real-time are good, need the overvoltage phenomenon to occur in the circuit; Simultaneously if the LED electric current is correctly fed back to elementary PFC, need can compatible different amplification optocoupler, that realizes producing is stable, reliable.Realize above function, single-stage PFC adjustment member is had further require: at first needing secondaryly has suitable quiescent point, if the working point is too high, and undesired, the bifurcated of metal-oxide-semiconductor voltage waveform in the time of can causing heavy load work; If the working point is excessively low, in the time of can causing the moment loading and unload load, output overvoltage; In addition, if quiescent point is improper, secondary adjustment loop also can job insecurity.
In order to obtain suitable quiescent point, the electric current of secondary optocoupler is correctly fed back to elementary PFC control unit, the utility model further provides preferred embodiment 3.Referring to Fig. 6, in this preferred embodiment 3, the tripod of described photoelectrical coupler is by the 5th grounding through resistance, the FB pin of described single-stage PFC control unit is by the 7th grounding through resistance, the VCC pin of described single-stage PFC control unit connects the 4th pin and the 8th resistance of described photoelectrical coupler simultaneously, the other end of described the 8th resistance connects the FB pin of described single-stage PFC control unit, and in addition, the other end of described the 8th resistance also connects the tripod of described photoelectrical coupler by the 6th resistance.Because the tripod at the optocoupler of secondary feedback signal unit connects a resistance R 10 over the ground, the electric current major part is all consumed over the ground by R10, dividing potential drop by resistance R 4 and R3 provides a bias voltage to chip first, approximately about 0.5V, setover by optocoupler behind the chip enable, realization is to the adjusting of output, and R10 is approximately 100:1 to the current ratio of earth-current and the output of adjustment chip.By the preferred embodiment 3 of Fig. 6, the A point of optocoupler output and the electric current of metal-oxide-semiconductor and voltage have all obtained effectively adjusting, and circuit has obtained suitable quiescent point.
Consider that the circuit among the embodiment 3 has many places to be connected with ground wire, for the ground wire cabling rationally is set in circuit, implement 3 preferred ground wire arrangements as shown in Figure 7, wherein, between the output of described rectifier bridge and ground, also be parallel with a capacitor C 31, be used for the high-frequency noise of filtering AC line.The ground wire access point has five places among Fig. 7, use respectively A1, B1, C1, D1, E1 represents, the total cabling principle of ground wire is: all ground wires cross at C1 place, chip ground, wherein, exchanging input, rectifier bridge is connected common land end A1 and connects and receive chip ground C1 after B1 is held on sampling resistor ground with filter capacitor C31, ZCD ground D1 and optocoupler adjustment ground E1 then receive respectively chip ground E1 independently, have optimized the cabling layout of circuit by this execution mode, make circuit realize more clear and definite.
At last, the utility model also provides a kind of liquid crystal display device, adopt the power control circuit of above-mentioned backlight to control, described display device can for: liquid crystal panel, Electronic Paper, oled panel, LCD TV, liquid crystal display, DPF, mobile phone, panel computer etc. have product or the parts of any Presentation Function.
In sum, in the technical solution of the utility model, directly control secondary output current and voltage owing to adopting single-stage PFC control unit, can realize the constant current control of LED, thereby saved elementary PFC control unit, LLC control unit and elementary large electrolysis than conventional architectures, thus reduced the control complexity of circuit, saved equipment cost, and improved stability and the reliability of circuit, do not make equipment fragile and be convenient to safeguard.
Above execution mode only is used for explanation the utility model; and be not limitation of the utility model; the those of ordinary skill in relevant technologies field; in the situation that do not break away from spirit and scope of the present utility model; can also make a variety of changes and modification; therefore all technical schemes that are equal to also belong to category of the present utility model, and real protection scope of the present utility model should be defined by the claims.
Claims (10)
1. a power control circuit is characterized in that, described circuit comprises:
Be arranged at AC input cell, rectifier bridge and the single-stage control unit of transformer alternating side, and the diode, LC oscillating circuit, LED lamp bar, LED current sampling resistor and the secondary feedback signal unit that are arranged at the transformer dc side; Wherein, described AC input cell, rectifier bridge and single-stage control unit are connected successively, described diode, LC oscillating circuit, LED lamp bar, LED current sampling resistor and secondary feedback signal unit, described secondary feedback signal unit is connected to described single-stage PFC control unit, provides secondary feedback signal to described single-stage PFC control unit.
2. circuit according to claim 1 is characterized in that, described transformer alternating side also is connected with the sampling resistor in parallel with described single-stage PFC control unit, and described sampling resistor is connected to described transformer by metal-oxide-semiconductor; Wherein, grid, CS pin and the GND pin that the Dri pin of described single-stage PFC control unit connects described metal-oxide-semiconductor connects respectively the two ends of described sampling resistor, and the source electrode of described metal-oxide-semiconductor connects described transformer, drain electrode and substrate and is connected and connects described sampling resistor; Also be parallel with a voltage stabilizing didoe between the source-drain electrode of described metal-oxide-semiconductor.
3. circuit according to claim 1 is characterized in that, described secondary feedback signal unit comprises a photoelectrical coupler.
4. circuit according to claim 1 is characterized in that, is connected with 4 triodes between the ZCD pin of described single-stage PFC control unit and the described transformer.
5. circuit according to claim 2, it is characterized in that, in described transformer alternating side, be connected to the first resistance between the CS pin of described sampling resistor and described single-stage PFC control unit, be connected to second resistance in parallel with described sampling resistor and the first resistance between the CS pin of described single-stage PFC control unit and GND pin, the CS pin of described single-stage PFC control unit is connected to the 3rd resistance and the 4th resistance of connecting, described the 3rd resistance and the 4th resistance and described transformers connected in parallel with the output of described rectifier bridge.
6. circuit according to claim 3, it is characterized in that, the tripod of described photoelectrical coupler is by the 5th grounding through resistance, the FB pin of described single-stage PFC control unit is by the 7th grounding through resistance, the VCC pin of described single-stage PFC control unit connects the 4th pin and the 8th resistance of described photoelectrical coupler simultaneously, the other end of described the 8th resistance connects the FB pin of described single-stage PFC control unit, in addition, the other end of described the 8th resistance also connects the tripod of described photoelectrical coupler by the 6th resistance.
7. circuit according to claim 1 is characterized in that, also is parallel with an electric capacity between the output of described rectifier bridge and ground.
8. a backlight module is characterized in that, comprises in the described backlight module such as each described power control circuit among the claim 1-7.
9. a liquid crystal display device is characterized in that, described liquid crystal display device comprises backlight module as claimed in claim 8.
10. liquid crystal display device according to claim 9 is characterized in that, described liquid crystal display device is LCD TV.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220278915 CN202696963U (en) | 2012-06-13 | 2012-06-13 | Power supply control circuit, backlight module and liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220278915 CN202696963U (en) | 2012-06-13 | 2012-06-13 | Power supply control circuit, backlight module and liquid crystal display device |
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| Publication Number | Publication Date |
|---|---|
| CN202696963U true CN202696963U (en) | 2013-01-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220278915 Expired - Fee Related CN202696963U (en) | 2012-06-13 | 2012-06-13 | Power supply control circuit, backlight module and liquid crystal display device |
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| CN (1) | CN202696963U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102740562A (en) * | 2012-06-13 | 2012-10-17 | 青岛海信电器股份有限公司 | Power control circuit, backlight module and liquid crystal display device |
-
2012
- 2012-06-13 CN CN 201220278915 patent/CN202696963U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102740562A (en) * | 2012-06-13 | 2012-10-17 | 青岛海信电器股份有限公司 | Power control circuit, backlight module and liquid crystal display device |
| CN102740562B (en) * | 2012-06-13 | 2014-11-05 | 青岛海信电器股份有限公司 | Power control circuit, backlight module and liquid crystal display device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130123 Termination date: 20200613 |