CN103368424A - Power supply circuit, backlight unit and liquid crystal display television - Google Patents
Power supply circuit, backlight unit and liquid crystal display television Download PDFInfo
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- CN103368424A CN103368424A CN2013103175431A CN201310317543A CN103368424A CN 103368424 A CN103368424 A CN 103368424A CN 2013103175431 A CN2013103175431 A CN 2013103175431A CN 201310317543 A CN201310317543 A CN 201310317543A CN 103368424 A CN103368424 A CN 103368424A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention provides a power supply circuit. The power supply circuit comprises a transformer, a resonance circuit, a control circuit and a first output circuit, wherein the input end of the resonance circuit is connected to one end of a secondary winding of the transformer, and the output end of the resonance circuit is connected with the first output circuit and used for receiving a first alternating current output by the transformer as well as outputting a second alternating current to the first output circuit; one end of a primary winding of the transformer is used for receiving a direct current from the outside, and the other end of the primary winding is connected to the control circuit and used for outputting the first alternating current according to a first driving signal and the direct current of the control circuit; and the control circuit is connected to the other end of the primary winding of the transformer and used for outputting the first driving signal to the transformer in order to adjust the frequency of the first alternating current. Correspondingly, the invention also provides a backlight unit and a liquid crystal display television. According to the technical scheme, the circuit structure can be simplified, the electromagnetic interference can be reduced, and thus the reliability of the circuit is improved.
Description
Technical field
The present invention relates to field of household appliances, in particular to a kind of power supply circuits, backlight module and a kind of LCD TV.
Background technology
The typical drive scheme of present linear LED-backlit technology is such as 1 and shown in Figure 2, Fig. 1 shows two kinds of different type of drive with Fig. 2, Fig. 1 adopts the BUCK(step-down to drive) drives LED lamp, Fig. 2 adopts BOOST (driving of boosting) drives LED lamp, basically present LED drives and all adopts this dual mode, as can be seen from the figure, the basic control unit of these two kinds of type of drive is substantially similar, inductance must be arranged, metal-oxide-semiconductor and diode (part that marks out among the figure), and special-purpose LED drives chip, wherein, control the stability of the voltage of an output circuit (power supply is to the output circuit of mainboard and power amplifier) by control chip, control the stability of the voltage of another output circuit (LED lamp part) by the LED control chip, be that two parts output circuit is separately to control, adopt respectively a chip to control, and this chip (namely special-purpose LED drives chip) also is EMC(Electro Magnetic Compatibility, Electro Magnetic Compatibility) noise source of disturbing, can produce very large EMI(Electro Magnetic Interference, electromagnetic interference), inductance is bulky simultaneously, can't miniaturization, PCB set type also can cause very large impact.
Therefore, need a kind of new power supply circuits, can simplify circuit structure, reduce electromagnetic interference.
Summary of the invention
The present invention just is being based on the problems referred to above, has proposed a kind of new power supply circuits, can simplify circuit structure, reduces electromagnetic interference.
In view of this, the present invention proposes a kind of power supply circuits, comprise: transformer, resonant circuit, control circuit and the first output circuit, wherein, the input of described resonant circuit is connected to an end of the secondary winding of described transformer, the output of described resonant circuit is connected with described the first output circuit, is used for receiving the first alternating current of described transformer output, and exports the second alternating current to described the first output circuit; One termination of the former limit winding of described transformer is received the direct current from the outside, and the other end of described former limit winding is connected to described control circuit, is used for exporting described the first alternating current according to the first driving signal and the described direct current of described control circuit; Described control circuit is connected to the other end of the former limit winding of described transformer, exports described first to described transformer and drives signal, to regulate the frequency of described the first alternating current.
Regulate the frequency of the alternating current of transformer secondary winding output by control circuit, the variation of frequency can make the voltage of the second alternating current of resonant circuit output change, like this, the frequency of regulating the first alternating current by control circuit just can be regulated the output voltage of resonant circuit, thereby the voltage of stable output is given the first output circuit, and this scheme has been saved boost driving or reduction voltage circuit and the LED control chip that adopts in the correlation technique, so not only simplified circuit, also reduced the space hold of pcb board, and because the LED control chip is larger to the electromagnetic interference that other devices cause, therefore save the electromagnetic interference that this LED control chip has also reduced whole power supply circuits afterwards.
According to a further aspect in the invention, provide a kind of backlight module, comprised the power supply circuits described in above-mentioned arbitrary technical scheme.Because the circuit structure of above-mentioned power supply circuits is succinct and can reduce electromagnetic interference when finishing original function, the backlight module that therefore has these power supply circuits is more frivolous, and electromagnetic interference is greatly improved.
According to another aspect of the invention, a kind of LCD TV also is provided, comprise the power supply circuits described in above-mentioned technical scheme, wherein, the first output circuit in the described power supply circuits is connected to the LED-backlit source of described LCD TV, be the power supply of described LED-backlit source, the second output circuit in the described power supply circuits is connected to the mainboard of described LCD TV, is described main board power supply.
By technical scheme of the present invention, dispense secondary control chip, adopt primary control chip and two feedback circuits to realize FEEDBACK CONTROL, a part is fed back to stable direct current, offers mainboard and power amplifier, and this voltage is generally 12V, this feedback can not be subjected to the impact of frequency change, a part is the LC resonant network in addition, utilizes the gain of resonance under different frequency of LC, the electric current of real-time adjustment LED lamp bar.Like this, adopt primary chip control, realize the integrated design of LED power drives, saved secondary control circuit, simple in circuits, reliability is high.
Description of drawings
Fig. 1 and Fig. 2 show respectively the schematic diagram of the power supply circuits in the correlation technique;
Fig. 3 shows the according to an embodiment of the invention block diagram of power supply circuits;
Fig. 4 shows the according to an embodiment of the invention schematic diagram of power supply circuits;
Fig. 5 shows the gain curve figure of the resonant circuit in the power supply circuits according to an embodiment of the invention.
Embodiment
In order more clearly to understand above-mentioned purpose of the present invention, feature and advantage, below in conjunction with the drawings and specific embodiments the present invention is further described in detail.Need to prove that in the situation of not conflicting, the application's embodiment and the feature among the embodiment can make up mutually.
A lot of details have been set forth in the following description so that fully understand the present invention; but; the present invention can also adopt other to be different from other modes described here and implement, and therefore, protection scope of the present invention is not subjected to the restriction of following public specific embodiment.
Fig. 3 shows the according to an embodiment of the invention block diagram of power supply circuits.
As shown in Figure 3, power supply circuits 300 according to an embodiment of the invention, comprise: transformer 302, resonant circuit 304, control circuit 306 and the first output circuit 308, wherein, the input of described resonant circuit 304 is connected to an end of the secondary winding of described transformer 302, the output of described resonant circuit 304 is connected with described the first output circuit 308, is used for receiving the first alternating current of described transformer 302 outputs, and to described the first output circuit 308 outputs the second alternating current; One termination of the former limit winding of described transformer 302 is received the direct current from the outside, the other end of described former limit winding is connected to described control circuit 306, is used for exporting described the first alternating current according to the first driving signal and the described direct current of described control circuit 306; Described control circuit 306 is connected to the other end of the former limit winding of described transformer 302, exports described first to described transformer and drives signal, to regulate the frequency of described the first alternating current.
First of control circuit 306 drives the current output terminal that signal output part is connected to the former limit winding of transformer 302, the current input terminal of this former limit winding is connected to the outside, this outside can provide the current source of direct current, it also can be the AC-DC conversion device, first of control circuit 306 drives signal and is actually the rhythmic high-low level signal of tool, utilize the principle of transformer 302, the break-make of the electric current of the former limit winding of control transformer 302 is so that go out to induce corresponding electric current at the secondary winding, and the induced current of secondary winding is associated with the break-make of the electric current of former limit winding, and the break-make of the electric current of former limit winding is to drive signal with first of control circuit 306 to be associated, therefore drive signal by first of adjusting control circuit 306, just can regulate the frequency of break-make of the electric current of former limit winding, and then the frequency of the alternating current of powerstat secondary winding output, the variation that inputs to the ac frequency of resonant circuit 304 can make the voltage of the second alternating current of resonant circuit 304 outputs change, like this, just can regulate the output voltage of resonant circuit by the frequency of control circuit 306 adjustings the first alternating current, therefore in order to stablize the voltage of the first output circuit 308, just can regulate the frequency of the first alternating current, thereby the voltage of stable output is given the first output circuit 308, and this scheme has been saved boost driving or reduction voltage circuit and the LED control chip that adopts in the correlation technique, so not only simplified circuit, also reduced the space hold of pcb board, and because the LED control chip is larger to the electromagnetic interference that other devices cause, therefore save the electromagnetic interference that this LED control chip has also reduced whole power supply circuits afterwards.
In technique scheme, preferably, described resonant circuit 304 comprises inductance and electric capacity, one end of described inductance is connected to the secondary winding of described transformer 302, the other end of described inductance is connected to described the first output circuit 308, one end of described electric capacity is connected between described inductance and described the first output circuit, the other end ground connection of described electric capacity, and described resonant circuit 304 is according to the output voltage of described second alternating current of the frequency change regulation output of described the first alternating current.
In this technical scheme, resonant circuit can use the LC resonant circuit, it can certainly be other forms of resonant circuit, like this, the frequency that only needs to regulate the first alternating current that transformer goes out just can adjust the output to the voltage of the first output circuit, guarantees that the first output circuit can obtain stable voltage.
In above-mentioned arbitrary technical scheme, preferably, power supply circuits can also comprise: the first feedback circuit 310, the input of described the first feedback circuit 310 is connected to described the first output circuit 308, the output of described the first feedback circuit 310 is connected to described control circuit 306, be used for gathering the first current value of described the first output circuit 308, and described the first current value is generated the first feedback signal feed back to described control circuit 306; Described control circuit 306 drives signal according to described the first feedback signal to described transformer 302 outputs described first.
In this technical scheme, obtain electric current in the first output circuit by the first feedback loop, go to send first according to the current value that obtains and first threshold by control circuit again and drive signal.For example, current value in the first output circuit that obtains is I1, first threshold is I0, and I1＜I0, be that the frequency of the alternating current of transformer input is f1 if the frequency of the first alternating current of transformer output this moment is f1(, and control circuit is by calculating, if want the current value adjustment in the first output circuit to I0, needing the frequency of the first alternating current of transformer output is f2, at this moment, control circuit sends first and drives signal, by this first frequency that drives the alternating current of Signal Regulation transformer input, the frequency of the first alternating current of transformer output can change along with the variation of the frequency of input, frequency with the alternating current of transformer input is adjusted to f2 by f1 like this, correspondingly, the frequency of the first alternating current of transformer output also changes to f2 by f1, electric current in such the first output circuit just can be raised to first threshold I0, thereby the current value adjustment in the first output circuit has been arrived desired value, therefore by constantly feeding back to the current value in the first circuit, constantly be adjusted to targets threshold, can guarantee electric current stable in the first output circuit.
In technique scheme, preferably, described the first feedback circuit 310 comprises the first optocoupler and sampling resistor, and described sampling resistor is connected to described the first output circuit, and the input of described optocoupler is connected between described sampling resistor and described the first output circuit.
Can use optocoupler as the feedback device of feedback circuit, since optocoupler with light as the media transmission signal of telecommunication, therefore realized the insulation between input and the output, namely so that the primary control circuit separate with secondary control circuit, but it will be understood by a person skilled in the art that feedback circuit includes but not limited to optocoupler.
In above-mentioned arbitrary technical scheme, preferably, described control circuit 306 comprises controller and mains switch, described controller is connected to described mains switch, described mains switch is connected to the other end of the former limit winding of described transformer, and described controller transmits control signal to described mains switch, makes described mains switch export described first and drives signal, control the break-make of described mains switch, with the frequency of the first alternating current of regulating the output of described transformer.
Control circuit is mainly realized control to the first alternating current by controller and Switching Power Supply, mains switch comprises MOS transistor, the switching devices such as triode, controller comprises control chip, the frequency of the turn-on and turn-off of controller by transmitting control signal to control MOS transistor to transistor, thereby the frequency of the alternating current of control transformer input, the frequency of the first alternating current of control transformer output indirectly, controlled the frequency of the first alternating current, again because frequency is the principal element that affects the resonant circuit output voltage, therefore, also indirectly control the output voltage of resonant circuit.
In above-mentioned arbitrary technical scheme, preferably, power supply circuits can also comprise: the first rectification circuit 312 and the second output circuit 314, the input of described the first rectification circuit 312 is connected to the secondary winding of described transformer 302, the output of described the first rectification circuit 312 is connected to described the second output circuit 314, the 3rd alternating current of 312 pairs of described transformer 302 outputs of described the first rectification circuit carries out exporting described the second output circuit 314 to after the rectification, alternating voltage has been become the direct voltage of pulsation.
In this technical scheme, transformer not only can be the voltage of the first output circuit stable output, also can be the second output circuit output voltage simultaneously, and it is stable to control simultaneously two voltages maintenances in the output circuit by a control circuit.Specific implementation is when regulating the voltage in the first output circuit in the frequency of the alternating current of the output by regulating transformer, at this moment, in order to guarantee that voltage in the second output circuit can not be subjected to the impact of frequency change, be converted to direct voltage by the frequency in the 3rd alternating current of the first rectification circuit filtering transformer output and with alternating voltage, so just guaranteed when the frequency of the alternating current of regulating transformer output, though regulated the electric current in the first output circuit, but can not produce on the electric current in the second output circuit any impact, realize utilizing same control circuit and same transformer just can reach the respectively control of the electric current of two-way output circuit.
In above-mentioned arbitrary technical scheme, preferably, power supply circuits can also comprise: the second feedback circuit 316, the input of described the second feedback circuit 316 is connected to described the second output circuit 314, the output of described the second feedback circuit 316 is connected to described control circuit 306, be used for gathering the second current value of described the second output circuit 314, and described the second current value is generated the second feedback signal feed back to described control circuit 306; Described control circuit 306 drives signal according to this second feedback signal to 302 outputs second of described transformer, with the duty ratio of described the 3rd alternating current of regulating described transformer 302 outputs.
In this technical scheme, the second feedback circuit gathers the second current value in the second output circuit, and feed back to control circuit, control circuit can be regulated electric current in the second output circuit according to feedback result equally like this, concrete, control circuit can be by regulating the transformer input the duty ratio of the 3rd alternating current of recently indirect regulation transformer output of duty of alternating current, thereby the pulsewidth of regulating the 3rd alternating current guarantees the stability of the voltage in the second output circuit.Because affecting the factor of the electric current in the first output circuit mainly is the frequency of alternating current, therefore, when the duty ratio of the alternating current of the secondary winding side of regulating transformer, can the electric current in the first output circuit not exerted an influence, so just can reach the purpose of only regulating the electric current in the second output circuit, the electric current of the first output circuit can not be affected.Therefore, drive chip even if saved original special-purpose LED, when the curtage of each load is regulated, interactional drawback can not appear, can realize the independent adjusting to the curtage of each load, also can simplify circuit, reduce taking up room and production cost of pcb board.
In above-mentioned arbitrary technical scheme, preferably, described the second feedback circuit 316 comprises the second optocoupler.
In above-mentioned arbitrary technical scheme, preferably, power supply circuits can also comprise: the second rectification circuit 318, carry out exporting to after the rectification the former limit winding of described transformer to the alternating current that receives.
Backlight module according to an embodiment of the invention comprises the power supply circuits described in above-mentioned arbitrary embodiment.Because the circuit structure of above-mentioned power supply circuits is succinct and can reduce electromagnetic interference when finishing original function, the backlight module that therefore has these power supply circuits is more frivolous, and electromagnetic interference is greatly improved.According to a further aspect in the invention, a kind of LCD TV also is provided, comprise the power supply circuits described in above-mentioned arbitrary technical scheme, wherein, the first output circuit in the described power supply circuits is connected to the LED-backlit source of LCD TV, be the power supply of described LED-backlit source, the second output circuit in the described power supply circuits is connected to mainboard or other function elements of stating LCD TV, is this mainboard or the power supply of other function elements.
Power supply circuits according to the present invention except can use with LCD TV, also can be applicable to the terminals such as panel computer, mobile phone.
Describe technical scheme of the present invention in detail below in conjunction with Fig. 4 and Fig. 5.
Fig. 4 shows the according to an embodiment of the invention schematic diagram of power supply circuits.
As shown in Figure 4, the course of work of power supply circuits is as follows according to an embodiment of the invention: the alternating current of reception exports the end of the former limit winding of transformer 302 to after filter circuit and rectifier bridge carry out rectification, the signal output part of control circuit 306 is connected to the other end of the former limit winding of transformer 302, control the break-make of the electric current of former limit winding, one end of the secondary winding of transformer is connected to the input of resonant circuit 304, the secondary winding induces corresponding alternating current according to the break-make of the electric current of former limit winding, thereby the electric current that resonant circuit 304 receives is alternating current, the voltage of 304 pairs of alternating currents that receive of resonant circuit is regulated, the output of resonant circuit 304 is connected to the input of the first output circuit 308, exports the electric current after overvoltage is processed to first output circuit 308.Wherein, the load of the first output circuit 308 can be the LED lamp, between the output and control circuit 306 of the first output circuit 308, connect first feedback circuit 310, the first current value that the first feedback circuit 310 gathers in the first output circuit 308, and generating the first feedback signal according to the first current value, to feed back to control circuit 306(be control chip among Fig. 1), this first feedback signal can be current signal, it also can be voltage signal, control circuit 306 drives signal (if the first feedback signal is current signal according to the first feedback signal to transformer 302 outputs first, then the current threshold with this current signal and setting compares, generate first according to comparative result and drive signal, if the first feedback signal is voltage signal, then the voltage threshold with voltage signal and setting compares, generate first according to comparative result and drive signal), frequency with the alternating current of regulating transformer output, frequency change, accordingly, the voltage of resonant circuit output will change to some extent, regulate voltage in the first output circuit by regulating frequency like this, thereby guarantee the stable of voltage in the first output circuit 308.
The other end at the secondary winding of transformer, also connected first rectification circuit 312, the output of the first rectification circuit 312 is connected to the second output circuit 314, the alternating current of 312 pairs of transformers of the first rectification circuit, 302 outputs carries out exporting the second output circuit 314 to after the rectification, wherein, the second output circuit 314 can provide power supply to mainboard etc., between the output and control circuit 306 of the second output circuit 314, connect second a feedback circuit 316(as shown in Figure 4, this second feedback circuit 316 can comprise an optocoupler and sampling resistor R1, R2), the second feedback circuit 316 gathers the second current value in the second output circuit 314, and generates the second feedback signal according to the second current value and feed back to control circuit 306; Control circuit 306 drives signal (in like manner according to the second feedback signal to transformer 302 outputs second, if the second feedback signal is current signal, then the current threshold with this current signal and setting compares, generate second according to comparative result and drive signal, if the second feedback signal is voltage signal, then the voltage threshold with voltage signal and setting compares, generate second according to comparative result and drive signal), duty ratio with the alternating current of regulating transformer 302 outputs, regulate the duty ratio of alternating current and can regulate the pulsewidth of alternating current, thereby stablize the voltage in the second output circuit 314.Wherein, during magnitude of voltage in regulating the first output circuit 308, what regulate is the frequency of alternating current, control the variation of resonant circuit output voltage by the variation of frequency, this moment is owing to be provided with the first rectification circuit before the second output circuit, so the variation of frequency can impact the voltage in the second output circuit 314 hardly, same, when the alternating current in the second output circuit 314 is regulated, because what regulate is duty ratio, therefore can exert an influence to the first output circuit hardly.Like this, can guarantee simultaneously electric current stable in the first output circuit and the second output circuit.
Although should be understood that only to show two-way output in above-described embodiment, in fact, it also can comprise the more output of multichannel, coming provides power supply for more load.
Fig. 5 shows the gain curve figure of resonant circuit in the power supply circuits according to an embodiment of the invention.
As shown in Figure 5, there is shown the gain curve figure of three kinds of quality factor (being respectively 0.4,0.8 and 1) of resonant circuit, as can be seen from the figure, no matter be any bar curve, at f
0When point, its corresponding resonance gain is 1, in frequency greater than f
0Shi Zengyi is less than 1, in frequency less than f
0The time, gain is greater than 1, and when gain became large, the voltage of resonant circuit output will raise.Because resonant circuit has this frequency and the interactional characteristic of gain, therefore power supply circuits can utilize this characteristic of resonant circuit to adjust the electric current of LED, namely utilize frequency to adjust the voltage of resonant circuit output, when the voltage of exporting to LED raises, the electric current of LED just raises, so when LED electric current during less than set point, feed back to control circuit by feedback circuit, in order to increase the electric current of LED, control circuit need reduce to input to the frequency of the alternating current of resonant circuit, this moment, the gain of resonant circuit just can become large, and the voltage of LC output will raise, thereby reaches the purpose of stabilizing LED current.
More than be described with reference to the accompanying drawings technical scheme of the present invention, by technical scheme of the present invention, dispense secondary control chip, adopt primary control chip and two feedback circuits to realize FEEDBACK CONTROL, a part is fed back to stable direct current, offer mainboard and power amplifier, this voltage is generally 12V, and this feedback can not be subjected to the impact of frequency change, and a part is the LC resonant network in addition, utilize the gain of resonance under different frequency of LC, the electric current of real-time adjustment LED lamp bar.Like this, adopt primary chip control, realize the integrated design of LED power drives, saved secondary control circuit, simple in circuits, reliability is high.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. power supply circuits is characterized in that, comprising: transformer, resonant circuit, control circuit and the first output circuit, wherein,
The input of described resonant circuit is connected to an end of the secondary winding of described transformer, the output of described resonant circuit is connected with described the first output circuit, be used for receiving the first alternating current of described transformer output, and export the second alternating current to described the first output circuit;
One termination of the former limit winding of described transformer is received the direct current from the outside, and the other end of described former limit winding is connected to described control circuit, is used for exporting described the first alternating current according to the first driving signal and the described direct current of described control circuit;
Described control circuit is connected to the other end of the former limit winding of described transformer, exports described first to described transformer and drives signal, to regulate the frequency of described the first alternating current.
2. power supply circuits according to claim 1, it is characterized in that, described resonant circuit comprises inductance and electric capacity, one end of described inductance is connected to the secondary winding of described transformer, the other end of described inductance is connected to described the first output circuit, one end of described electric capacity is connected between described inductance and described the first output circuit, the other end ground connection of described electric capacity, and described resonant circuit is according to the output voltage of described second alternating current of the frequency change regulation output of described the first alternating current.
3. power supply circuits according to claim 1 is characterized in that, also comprise:
The first feedback circuit, the input of described the first feedback circuit is connected to described the first output circuit, the output of described the first feedback circuit is connected to described control circuit, be used for gathering the first current value of described the first output circuit, and generate the first feedback signal according to described the first current value and feed back to described control circuit;
Described control circuit is exported described first according to described the first feedback signal to described transformer and is driven signal.
4. power supply circuits according to claim 3, it is characterized in that, described the first feedback circuit comprises the first optocoupler and sampling resistor, described sampling resistor is connected to described the first output circuit, and the input of described optocoupler is connected between described sampling resistor and described the first output circuit.
5. power supply circuits according to claim 1, it is characterized in that, described control circuit comprises controller and mains switch, described controller is connected to described mains switch, described mains switch is connected to the other end of the former limit winding of described transformer, and described controller transmits control signal to described mains switch, controls the break-make of described mains switch, make described mains switch export described first and drive signal, with the frequency of the first alternating current of regulating described transformer output.
6. each described power supply circuits in 5 according to claim 1 is characterized in that, also comprise:
The first rectification circuit and the second output circuit, the input of described the first rectification circuit is connected to the secondary winding of described transformer, the output of described the first rectification circuit is connected to described the second output circuit, and described the first rectification circuit carries out exporting described the second output circuit to after the rectification to the 3rd alternating current of described transformer output.
7. power supply circuits according to claim 6 is characterized in that, also comprise:
The second feedback circuit, the input of described the second feedback circuit is connected to described the second output circuit, the output of described the second feedback circuit is connected to described control circuit, be used for gathering the value of described the second output circuit, and generate the second feedback signal according to described the second current value and feed back to described control circuit;
Described control circuit drives signal according to described the second feedback signal to described transformer output second, with the duty ratio of described the 3rd alternating current of regulating described transformer output.
8. power supply circuits according to claim 7 is characterized in that, described the second feedback circuit comprises the second optocoupler.
9. a backlight module is characterized in that, comprises such as each described power supply circuits in the claim 1 to 8.
10. LCD TV, it is characterized in that, comprise such as each described power supply circuits in the claim 1 to 8, wherein, the first output circuit in the described power supply circuits is connected to the LED-backlit source of described LCD TV, be the power supply of described LED-backlit source, the second output circuit in the described power supply circuits is connected to the mainboard of described LCD TV, is described main board power supply.
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| CN2013103175431A CN103368424A (en) | 2013-07-25 | 2013-07-25 | Power supply circuit, backlight unit and liquid crystal display television |
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| CN2013103175431A CN103368424A (en) | 2013-07-25 | 2013-07-25 | Power supply circuit, backlight unit and liquid crystal display television |
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| CN105307305A (en) * | 2015-11-18 | 2016-02-03 | 深圳创维－Rgb电子有限公司 | LED power supply control device and TV set |
| CN105825807A (en) * | 2016-05-30 | 2016-08-03 | 河南通达多媒体制作有限公司 | Full-color LED display system |
| CN105825807B (en) * | 2016-05-30 | 2018-08-28 | 河南通达多媒体制作有限公司 | A kind of full color LED display system |
| WO2023109168A1 (en) * | 2021-12-14 | 2023-06-22 | 海信视像科技股份有限公司 | Display device and display control method |
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