CN100539782C - Light source driving circuit and driving method thereof - Google Patents

Light source driving circuit and driving method thereof Download PDF

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Publication number
CN100539782C
CN100539782C CNB2006101484394A CN200610148439A CN100539782C CN 100539782 C CN100539782 C CN 100539782C CN B2006101484394 A CNB2006101484394 A CN B2006101484394A CN 200610148439 A CN200610148439 A CN 200610148439A CN 100539782 C CN100539782 C CN 100539782C
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circuit
coupled
terminal
feedback
impedance
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CN101179882A (en
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陈弼先
赵翰楀
林信彰
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Cpt Display Technology (shenzhen)co Ltd
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Chunghwa Picture Tubes Ltd
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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
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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Abstract

The invention discloses a light source driving circuit which is used for driving a light-emitting element and comprises a power supply voltage supply circuit, a dimming circuit and a feedback circuit. The output end of the power supply voltage supply circuit is coupled to one end of the light-emitting element and used for supplying a power supply voltage to the light-emitting element, and the magnitude of the power supply voltage is determined according to a feedback signal received by the feedback end of the power supply voltage supply circuit. The first end of the dimming circuit is coupled to the other end of the light emitting element, the second end of the dimming circuit is coupled to the common potential, and the first end and the second end of the dimming circuit are determined to be in a conducting state according to the logic state of a pulse width signal. The first end of the feedback circuit is coupled to the first end of the first dimming circuit, the second end of the feedback circuit is coupled to the feedback end of the power supply voltage supply circuit, and the feedback signal is determined according to the conducting state of the dimming circuit.

Description

Light source driving circuit and driving method thereof
Technical field
The present invention is relevant for a kind of drive circuit, and is particularly to a kind of light source driving circuit of driven light-emitting element.
Background technology
Light source driving circuit, its application is very extensive, light-emitting diode (LED) drive circuit of backlight liquid crystal display drive circuit or hand-hold type mobile device for example, and have the high development potentiality.Wherein there are many advantages to be enhanced constantly and to promote, comprise that energy conversion efficiency increases, stability promotes or the like.
Existing framework in order to the light source driving circuit that drives one (string) light-emitting diode 106 as shown in Figure 1, this circuit comprises power supply voltage converter 101, output voltage feedback circuit 102, output capacitor 103, sequential control circuit 104 and the light adjusting circuit 105 of DC-DC.Wherein light adjusting circuit 105 is coupled between the negative electrode and common electric potential GND of light emitting diode string 106, and receives the pulse width signal PWM that sequential control circuit 104 is exported.In addition, output voltage feedback circuit 102 utilizes the resistance of two series connection to implement.
Power supply voltage converter 101 supplying DC power source voltages are given light emitting diode string 106, and see through the signal stabilization output voltage that output voltage feedback circuit 102 is fed back.Sequential control circuit 104 determines the width of the pulse width signal PWM that it is exported according to the brightness that the user sets.105 conductings when pulse width signal PWM is in high potential of light adjusting circuit end when making pulse width signal PWM be in electronegative potential.See through the width of adjusting pulse width signal PWM, the conducting state of control light adjusting circuit 105 is further controlled light emitting diode string 106 and whether is flow through electric current.So, when setting brightness was brighter, the time of pulse width signal PWM high potential was longer, and light adjusting circuit 105 ON time are longer, and the brightness of light emitting diode string 106 is also brighter.Otherwise when setting brightness was dark, the time of pulse width signal PWM high potential was shorter, and light adjusting circuit 105 ON time are shorter, and the brightness of light emitting diode string 106 is also darker.
Yet, when pulse width signal PWM is in electronegative potential, light adjusting circuit 105 not conductings, this moment, the pressure drop of the output voltage that power supply voltage converter 101 is supplied all dropped on the light adjusting circuit 105.When light emitting diode string 106 series connection are a lot, the output voltage that power supply voltage converter 101 is supplied will be very high, when light adjusting circuit 105 withstand voltage not enough, the output voltage that will cause light adjusting circuit 105 to be supplied by power supply voltage converter 101 punctures, and causes its 105 damage.In addition, also may therefore need to use withstand voltage higher light adjusting circuit 105, yet, withstand voltage higher light adjusting circuit 105 certainly will need bigger volume and higher price, except the volume that may increase integrated circuit, more increase the cost of circuit, also therefore reduced the competitiveness of product on market.
Summary of the invention
Purpose of the present invention is providing a kind of light source driving circuit exactly, in order to adaptive adjustment output voltage, damages to prevent the light source driving circuit inner member, prolongs the useful life of light source driving circuit.
A further object of the present invention provides a kind of light source driving circuit, in order to lower the cost of light source driving circuit inner member, to reach the increase product competitiveness.
The present invention proposes a kind of light source driving circuit, and in order to drive first light-emitting component, this light source driving circuit comprises: supply voltage supply circuit, first light adjusting circuit and feedback circuit.The output of supply voltage supply circuit couples an end of first light-emitting component, is supplied to the size of the supply voltage of output according to the feedback signal decision that its feedback end received.First end of first light adjusting circuit is coupled to the other end of first light-emitting component, and its second end couples common electric potential, and wherein first light adjusting circuit determines the conducting state of its first end and its second end according to the logic state of a pulse width signal.First end of feedback circuit is coupled to first end of first light adjusting circuit, and second end of feedback circuit is coupled to the feedback end of supply voltage supply circuit, according to the conducting state of first light adjusting circuit, and the decision feedback signal.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned feedback circuit also comprises the 3rd end, and the 3rd end of feedback circuit is coupled to the output of supply voltage supply circuit, according to the size decision feedback signal of supply voltage.Feedback circuit in one embodiment comprises: impedance circuit for detecting and feedback voltage control circuit.First end of impedance circuit for detecting couples first end of first light adjusting circuit, and its second end couples common electric potential.The current potential that it is exported according to the sense terminal of the decision of the impedance between second end of first end of impedance circuit for detecting and impedance circuit for detecting impedance circuit for detecting.The input of feedback voltage control circuit couples the sense terminal of impedance circuit for detecting, according to the current potential that the sense terminal of this impedance circuit for detecting is exported, controls the voltage swing of its output output feedback signal.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned impedance circuit for detecting comprises first impedance component and second impedance component.A first impedor end is first end of impedance circuit for detecting, and its other end is the sense terminal of impedance circuit for detecting.A second impedor end couples the first impedor other end, and its other end couples common electric potential.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned feedback voltage control circuit comprises operational amplifier, it comprises first input end, second input and output, its output couples the feedback end of supply voltage supply circuit, its first input end couples the sense terminal of impedance circuit for detecting, and its second input couples a reference voltage.In an embodiment, the feedback voltage control circuit also comprises first diode and second diode, and the negative electrode of first diode couples the output of operational amplifier, and its anode couples the output of supply voltage supply circuit.The negative electrode of second diode couples the anode of first diode, and its anode couples the feedback end of supply voltage supply circuit.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned feedback voltage control circuit also comprises: the 3rd impedance component and output voltage feedback circuit.The 3rd an impedor end couples the anode of first diode, and its other end couples the output of supply voltage supply circuit.The output voltage feedback circuit is coupled between the feedback end of the output of supply voltage supply circuit and supply voltage supply circuit, in order to the size according to the output voltage decision feedback voltage of supply voltage supply circuit.In an embodiment, the output voltage feedback circuit comprises the 4th impedance component and the 5th impedance component.The 4th an impedor end couples the output of supply voltage supply circuit, and its other end couples the feedback end of supply voltage supply circuit.The 5th an impedor end couples the 4th impedor other end, and its other end couples common electric potential.
According to the described light source driving circuit of preferred embodiment of the present invention, comprise that also sequential control circuit couples first light adjusting circuit, in order to the brightness settings that the user imported, is converted to pulse width signal.In the embodiment of light source driving circuit, wherein first light-emitting component is at least one light-emitting diode, and its anode couples the output of supply voltage supply circuit.
The present invention is because of adopting the conducting state of feedback circuit according to light adjusting circuit, the decision feedback signal, therefore to see through the means that change feedback signal, reach adaptive adjustment output voltage, further prevent the light adjusting circuit component wear of light source driving circuit inside, prolong the useful life of light source driving circuit.In addition, because therefore adaptive adjustment output voltage just need not to use high price and withstand voltage higher light adjusting circuit, further reach the cost that lowers the light source driving circuit inner member, product competitiveness also and then promotes more.
For above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, preferred embodiment cited below particularly, and conjunction with figs. is described in detail below.
Description of drawings
Fig. 1 is existing circuit diagram in order to the light source driving circuit that drives a string light-emitting diode 106.
Fig. 2 is the circuit diagram of the light source driving circuit of first embodiment of the invention.
Fig. 3 is the circuit diagram of the light source driving circuit of second embodiment of the invention.
Fig. 4 is the circuit diagram of the light source driving circuit of third embodiment of the invention.
Fig. 5 is the circuit diagram of the light source driving circuit of fourth embodiment of the invention.
Fig. 6 is the circuit diagram of the light source driving circuit of fifth embodiment of the invention.
Embodiment
Fig. 2 is the circuit diagram of the light source driving circuit of first embodiment of the invention.This light source driving circuit please refer to Fig. 2 in order to driven light-emitting element 204, and this light source driving circuit mainly comprises supply voltage supply circuit 201, light adjusting circuit 202 and feedback circuit 203.The supply voltage supply circuit 201 of the foregoing description is not limited to specific certain supply voltage supply circuit, such as voltage-dropping type (buck), booster type (boost), buck-boost type (buck-boost) supply voltage supply circuit and the above-mentioned supply voltage supply circuit various topology of being derived for example forward (forward), return speed (flyback), half-bridge, full-bridge or the like, also or linear voltage regulator all can be in order to implement embodiments of the invention.In addition, for the foregoing description is described, in Fig. 2, indicate a node voltage Vn.
The output of supply voltage supply circuit 201 couples an end of light-emitting component, gives light-emitting component 204 in order to supply a supply voltage Vpp, and determines the size of the supply voltage that it is supplied according to the feedback signal FB that its feedback end received.Light adjusting circuit 202 is coupled between the other end and common electric potential GND of light-emitting component 204, and it determines the conducting state between light-emitting component 204 and the common electric potential GND according to the logic state of a pulse width signal PWM.When brightness settings was brighter, pulse width signal PWM was longer in the time of logic high potential, and the time of light adjusting circuit 202 conductings is also longer, so light-emitting component 204 also thereby brighter.
Feedback circuit 203 is coupled between the feedback end of light adjusting circuit 202 and supply voltage supply circuit 201, according to the conducting state of light adjusting circuit 202, and the decision feedback signal.For example light adjusting circuit 202 by the time because the supply voltage supply circuit is in almost no-load condition 201 this moments, so supply voltage Vpp can continue to rise, thereby the voltage Vn that causes light adjusting circuit 202 to be carried and then rises.This moment feedback circuit 203 detect light adjusting circuit 202 by the time, just control the feedback signal FB that feedback end received of supply voltage supply circuit 201, further control supply voltage Vpp descends, make voltage Vn that this light adjusting circuit 202 carried in the safe range that circuit can carry, so the useful life of light source driving circuit also thereby prolonged.
What deserves to be mentioned is, though the light source driving circuit of the embodiment of the invention has been depicted a possible kenel in the foregoing description, but knowing this operator should know, each manufacturer is all different for the design of feedback circuit and light adjusting circuit, and therefore the application of invention is when being not restricted to the possible kenel of this kind.In other words, so long as feedback circuit 203 is coupled between light adjusting circuit 202 and the supply voltage supply circuit 201, and, be to have met spiritual place of the present invention just according to the conducting state Control and Feedback signal FB of light adjusting circuit 202.
Fig. 3 is the circuit diagram of the light source driving circuit of second embodiment of the invention.Please refer to Fig. 3, wherein, light-emitting component 204 (shown in Figure 2) comprises the light-emitting diode L301 that a string anode couples negative electrode at this, wherein the anode of first light-emitting diode couples the output of supply voltage supply circuit 201, and feedback circuit 203 (shown in Figure 2) comprises resistance R 301～R305, diode D301～D302 and operational amplifier A 301.In addition, increased a sequential control circuit T301 at present embodiment, in order to the brightness settings that sets according to the user, its pulse width signal PWM who exports of output decision.
Below will utilize the logic current potential of the pulse width signal PWM that sequential control circuit T301 exported, be divided into two parts explanation present embodiment.
At first, when sequential control circuit T301 was output as logic high potential, this moment, light adjusting circuit 202 was a conducting state, and therefore the pressure drop that drops between light adjusting circuit 202 and the common electric potential GND is lower.The impedance of resistance R 301 and R302 dividing potential drop detecting light adjusting circuit 202, for example when light adjusting circuit 202 not conductings, just light adjusting circuit 202 is in high impedance status, the dividing potential drop that the end points that this moment, resistance R 301 and R302 were coupled obtains will be higher current potential, when light adjusting circuit 202 conductings, just light adjusting circuit 202 is in low impedance state, and the dividing potential drop that the end points that this moment, resistance R 301 and R302 were coupled obtains will be lower current potential.
The negative input end of operational amplifier A 301 couples resistance R 301 and R302, and the positive input terminal of operational amplifier A 301 couples a reference voltage VREF.With this embodiment, this operational amplifier A 301 can design usually and make its gain enough big, and reference voltage VREF is a fixing voltage.When light adjusting circuit 202 conductings, the voltage that negative input end received of operational amplifier A 301 will be lower than reference voltage VREF, because the gain of operational amplifier A 301 is enough big, the current potential that makes operational amplifier A 301 outputs export is positive sticking potential (high potential).Because the current potential that operational amplifier A 301 outputs are exported is positive sticking potential (high potential), so diode D301 and not conducting of D302.The size of feedback signal FB is also just determined by resistance R 303 and the formed output voltage feedback circuit of R304.The supply voltage Vpp that supply voltage supply circuit 201 is exported sees through feedback signal FB and reaches stable.
When sequential control circuit T301 is output as logic low potential, this moment, light adjusting circuit 202 was a not on-state, therefore the pressure drop that drops between light adjusting circuit 202 and the common electric potential GND is higher, and the dividing potential drop that the end points that this moment, resistance R 301 and R302 were coupled obtains will be higher current potential.The voltage that negative input end received of operational amplifier A 301 will be than reference voltage VREF height, because the gain of operational amplifier A 301 is enough big, the current potential that makes operational amplifier A 301 outputs export is negative sticking potential (electronegative potential).Because the current potential that operational amplifier A 301 outputs are exported is negative sticking potential (electronegative potential), so diode D301 and D302 conducting.Feedback signal FB will see through diode D301 and D302 is dragged down, and after supply voltage supply circuit 201 receives the feedback signal FB that is dragged down, also follows the supply voltage Vpp with its output to drag down.
By the above embodiments, can find, when light adjusting circuit 202 not conductings, by the feedback circuit Control and Feedback signal FB that top embodiment implemented, just can reach the effect that reduces output voltage, can prevent that so just light adjusting circuit 202 from damaging, and prolongs the useful life of circuit.In addition, because when light adjusting circuit 202 not conductings, turn down supply voltage Vpp, therefore just can need higher withstand voltage light adjusting circuit 202 originally than low price and 202 replacements of withstand voltage lower light adjusting circuit, further reach the cost that lowers the light source driving circuit inner member, increase competitiveness of product.
Fig. 4 is the circuit diagram of the light source driving circuit of third embodiment of the invention.Please also refer to Fig. 4 and Fig. 3, the circuit of this Fig. 4 and the circuit differences of Fig. 3 be Fig. 4 than Fig. 3 Duoed one group of light-emitting diode L401 with and corresponding light adjusting circuit 402, yet this circuit only needs to add feedback circuit at original light-emitting diode L301 and light adjusting circuit 202, just can reach the effect that when light adjusting circuit 202 not conductings, reduces output voltage, its circuit theory with Fig. 3 is identical, so do not repeat them here.In addition, though present embodiment uses two groups of light-emitting diode L401 and L301 and two groups of light adjusting circuits 202 and 402, yet, if use multi-group light-emitting diode and organize light adjusting circuit more and also can implement.
Fig. 5 is the circuit diagram of the light source driving circuit of fourth embodiment of the invention.Please also refer to Fig. 5 and Fig. 3, the difference of the circuit of this Fig. 5 and the circuit of Fig. 3 is that it is L501, L502 and L503 that Fig. 5 has been Duoed 3 groups of light-emitting diodes than Fig. 3, light adjusting circuit is also many in addition 3 current channels, its running is to see through the conducting state that pulse width signal PWM determines 4 groups of light-emitting diode L301, L501, L502 and L503 equally.Same reason, the circuit of Fig. 5 also only need add feedback circuit Control and Feedback signal FB between light-emitting diode L301 and light adjusting circuit 202, just can reach the effect that reduces output voltage when light adjusting circuit 202 not conductings, its principle with the circuit of Fig. 3 is identical, so do not repeat them here.In addition, though the light adjusting circuit 202 that present embodiment uses 4 groups of light-emitting diode L301, L501～L503 and 4 current channels are arranged, right this area has knows that usually the knowledgeable should know by inference, as long as use two groups of above light-emitting diodes and the above light adjusting circuit 202 of two passages just can implement.
Fig. 6 is the circuit diagram of the light source driving circuit of fifth embodiment of the invention.Please also refer to Fig. 6 and Fig. 3, the difference of the circuit of this Fig. 6 and the circuit of Fig. 3 is that Fig. 6 Duoed one group of light-emitting diode L601 and many one group of light adjusting circuits 602 and further add resistance R 601, R602 and diode D601 and D602 than Fig. 3.Its running is to see through the conducting state that pulse width signal PWM determines these 2 groups of light-emitting diode L301, L601 equally.The difference of this embodiment and Fig. 4, Fig. 5 is that Fig. 4 and Fig. 5 all adopt the conducting state of one of them light-emitting component of detecting or a light adjusting circuit, with Control and Feedback signal FB, yet this embodiment sees through the first impedance circuit for detecting to comprise that resistance R 301, R302, diode D602 and the second impedance circuit for detecting comprise resistance R 601, R602, diode D601 detect the conducting state of two light-emitting component L301 and L501 and two light adjusting circuits 202,602 simultaneously with Control and Feedback signal FB.This area has knows that usually the knowledgeable should know the running of Fig. 6 circuit by inference with reference to the embodiment of figure 3～Fig. 5, so do not repeat them here.
In sum, the present invention is because of adopting the conducting state of feedback circuit according to light adjusting circuit, the decision feedback signal, therefore to see through the means that change feedback signal, reach adaptive adjustment output voltage, further prevent the light adjusting circuit component wear of light source driving circuit inside, prolong the useful life of light source driving circuit.In addition, because therefore adaptive adjustment output voltage just need not to use high price and withstand voltage higher light adjusting circuit, further reach the cost that lowers the light source driving circuit inner member, product competitiveness also and then promotes more.
Though the present invention discloses as above with preferred embodiment; right its is not in order to qualification the present invention, any those of ordinary skills, without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is when with being as the criterion that claim was defined.

Claims (25)

1.一种光源驱动电路，用以驱动一第一发光元件，包括：1. A light source driving circuit for driving a first light-emitting element, comprising: 一电源电压供应电路，具有输出端与反馈端，其输出端耦接该第一发光元件的一端，用以供应一电源电压给该第一发光元件，并根据其反馈端所接收的一反馈信号决定该电源电压的大小；A power supply voltage supply circuit has an output terminal and a feedback terminal, and the output terminal is coupled to one end of the first light-emitting element for supplying a power supply voltage to the first light-emitting element, and according to a feedback signal received by the feedback terminal Determine the size of the power supply voltage; 一第一调光电路，其第一端耦接于该第一发光元件的另一端，其第二端耦接一共同电位，其中该第一调光电路根据一脉宽信号的逻辑状态，决定其第一端与其第二端的导通状态；以及A first dimming circuit, the first end of which is coupled to the other end of the first light-emitting element, and the second end of which is coupled to a common potential, wherein the first dimming circuit determines according to the logic state of a pulse width signal the conduction state between its first terminal and its second terminal; and 一反馈电路，所述反馈电路的第一端耦接于该第一调光电路的第一端，所述反馈电路的第二端耦接至该电源电压供应电路的反馈端，根据该第一调光电路的导通状态，决定该反馈信号。a feedback circuit, the first terminal of the feedback circuit is coupled to the first terminal of the first dimming circuit, the second terminal of the feedback circuit is coupled to the feedback terminal of the power supply voltage supply circuit, according to the first The conduction state of the dimming circuit determines the feedback signal. 2.如权利要求1所述的光源驱动电路，其特征在于，该反馈电路还包括第三端，所述反馈电路的第三端耦接于该电源电压供应电路的输出端，根据该电源电压的大小决定反馈信号。2. The light source driving circuit according to claim 1, wherein the feedback circuit further comprises a third terminal, the third terminal of the feedback circuit is coupled to the output terminal of the power supply voltage supply circuit, and according to the power supply voltage The magnitude of determines the feedback signal. 3.如权利要求1所述的光源驱动电路，其特征在于，该反馈电路包括：3. The light source driving circuit according to claim 1, wherein the feedback circuit comprises: 一阻抗侦测电路，包括第一端、第二端与侦测端，其第一端耦接该第一调光电路的第一端，其第二端耦接该共同电位，用以根据该阻抗侦测电路的第一端与该阻抗侦测电路的第二端之间的阻抗决定该阻抗侦测电路的侦测端所输出的电位；以及An impedance detection circuit, including a first terminal, a second terminal and a detection terminal, the first terminal of which is coupled to the first terminal of the first dimming circuit, and the second terminal of which is coupled to the common potential, for use in accordance with the The impedance between the first end of the impedance detection circuit and the second end of the impedance detection circuit determines the potential output by the detection end of the impedance detection circuit; and 一反馈电压控制电路，其输入端耦接该阻抗侦测电路的侦测端，其输出端输出该反馈信号，用以根据该阻抗侦测电路的侦测端所输出的电位，控制该反馈信号的电压大小。A feedback voltage control circuit, the input end of which is coupled to the detection end of the impedance detection circuit, and the output end outputs the feedback signal for controlling the feedback signal according to the potential output from the detection end of the impedance detection circuit voltage size. 4.如权利要求3所述的光源驱动电路，其特征在于，该阻抗侦测电路包括：4. The light source driving circuit according to claim 3, wherein the impedance detection circuit comprises: 一第一阻抗元件，其一端为该阻抗侦测电路的第一端，其另一端为该阻抗侦测电路的侦测端；以及a first impedance element, one end of which is the first end of the impedance detection circuit, and the other end is the detection end of the impedance detection circuit; and 一第二阻抗元件，其一端耦接该第一阻抗元件的另一端，其另一端耦接该共同电位。A second impedance element, one end of which is coupled to the other end of the first impedance element, and the other end of which is coupled to the common potential. 5.如权利要求3所述的光源驱动电路，其特征在于，该反馈电压控制电路包括：5. The light source driving circuit according to claim 3, wherein the feedback voltage control circuit comprises: 一运算放大器，其包括第一输入端、第二输入端以及输出端，其输出端耦接该电源电压供应电路的反馈端，其第一输入端耦接该阻抗侦测电路的侦测端，其第二输入端耦接一参考电压。An operational amplifier, which includes a first input terminal, a second input terminal and an output terminal, the output terminal is coupled to the feedback terminal of the power supply voltage supply circuit, and the first input terminal is coupled to the detection terminal of the impedance detection circuit, Its second input terminal is coupled to a reference voltage. 6.如权利要求5所述的光源驱动电路，其特征在于，该反馈电压控制电路还包括：6. The light source driving circuit according to claim 5, wherein the feedback voltage control circuit further comprises: 一第一二极管，其阴极耦接该运算放大器的输出端，其阳极耦接该电源电压供应电路的输出端。A first diode, its cathode is coupled to the output terminal of the operational amplifier, and its anode is coupled to the output terminal of the power supply voltage supply circuit. 7.如权利要求6所述的光源驱动电路，其特征在于，该反馈电压控制电路还包括：7. The light source driving circuit according to claim 6, wherein the feedback voltage control circuit further comprises: 一第二二极管，其阴极耦接该第一二极管的阳极，其阳极耦接该电源电压供应电路的反馈端。A second diode, the cathode of which is coupled to the anode of the first diode, and the anode of which is coupled to the feedback terminal of the power supply voltage supply circuit. 8.如权利要求7所述的光源驱动电路，其特征在于，该反馈电压控制电路还包括：8. The light source driving circuit according to claim 7, wherein the feedback voltage control circuit further comprises: 一第三阻抗元件，其一端耦接该第一二极管的阳极，其另一端耦接该电源电压供应电路的输出端。A third impedance element, one end of which is coupled to the anode of the first diode, and the other end of which is coupled to the output end of the power voltage supply circuit. 9.如权利要求3所述的光源驱动电路，其特征在于，该反馈电路还包括：9. The light source driving circuit according to claim 3, wherein the feedback circuit further comprises: 一输出电压反馈电路，耦接于该电源电压供应电路的输出端与该电源电压供应电路的反馈端之间，用以根据电源电压供应电路的输出电压决定该反馈电压的大小。An output voltage feedback circuit, coupled between the output terminal of the power supply circuit and the feedback terminal of the power supply circuit, is used to determine the magnitude of the feedback voltage according to the output voltage of the power supply circuit. 10.如权利要求9所述的光源驱动电路，其特征在于，该输出电压反馈电路包括：10. The light source driving circuit according to claim 9, wherein the output voltage feedback circuit comprises: 一第四阻抗元件，其一端耦接该电源电压供应电路的输出端，其另一端耦接该电源电压供应电路的反馈端；以及A fourth impedance element, one end of which is coupled to the output end of the power supply voltage supply circuit, and the other end of which is coupled to the feedback end of the power supply voltage supply circuit; and 一第五阻抗元件，其一端耦接该第四阻抗元件的另一端，其另一端耦接该共同电位。A fifth impedance element, one end of which is coupled to the other end of the fourth impedance element, and the other end of which is coupled to the common potential. 11.如权利要求1所述的光源驱动电路，其特征在于，还包括：11. The light source driving circuit according to claim 1, further comprising: 一时序控制电路，耦接该第一调光电路，用以将使用者所输入的亮度设定，转换为该脉宽信号。A timing control circuit, coupled to the first dimming circuit, is used to convert the brightness setting input by the user into the pulse width signal. 12.如权利要求1所述的光源驱动电路，其特征在于，该第一发光元件为一发光二极管，其阳极耦接该电源电压供应电路的输出端。12. The light source driving circuit as claimed in claim 1, wherein the first light-emitting element is a light-emitting diode, the anode of which is coupled to the output end of the power supply circuit. 13.如权利要求1所述的光源驱动电路，其特征在于，该第一发光元件为多个发光二极管，该些发光二极管以阳极耦接阴极的方式串接，其中第一个发光二极管的阳极耦接该电源电压供应电路的输出端。13. The light source driving circuit according to claim 1, wherein the first light-emitting element is a plurality of light-emitting diodes, and the light-emitting diodes are connected in series in a manner that the anode is coupled to the cathode, wherein the anode of the first light-emitting diode coupled to the output end of the power voltage supply circuit. 14.如权利要求1所述的光源驱动电路，其特征在于，此光源驱动电路还用以驱动一第二发光元件，且该第一调光电路还包括第三端耦接该第二发光元件，根据该脉宽信号的逻辑状态，决定其第三端与其第二端的导通状态。14. The light source driving circuit according to claim 1, wherein the light source driving circuit is also used to drive a second light-emitting element, and the first dimming circuit further includes a third terminal coupled to the second light-emitting element According to the logic state of the pulse width signal, the conduction state of the third terminal and the second terminal is determined. 15.如权利要求1所述的光源驱动电路，其特征在于，此光源驱动电路还用以驱动一第二发光元件，且此光源驱动电路还包括：15. The light source driving circuit according to claim 1, wherein the light source driving circuit is also used to drive a second light-emitting element, and the light source driving circuit further comprises: 一第二调光电路，其第一端耦接于该第二发光元件的另一端，其第二端耦接该共同电位，其中该第二调光电路根据该脉宽信号的逻辑状态，决定其第一端与其第二端的导通状态。A second dimming circuit, the first end of which is coupled to the other end of the second light-emitting element, and the second end is coupled to the common potential, wherein the second dimming circuit determines according to the logic state of the pulse width signal The conduction state between its first terminal and its second terminal. 16.如权利要求15所述的光源驱动电路，其特征在于，该反馈电路包括：16. The light source driving circuit according to claim 15, wherein the feedback circuit comprises: 一第一阻抗侦测电路，包括第一端、第二端与侦测端，其第一端耦接该第一调光电路的第一端，其第二端耦接该共同电位，用以根据该阻抗侦测电路的第一端与该阻抗侦测电路的第二端之间的阻抗决定该阻抗侦测电路的侦测端所输出的电位；A first impedance detection circuit, including a first terminal, a second terminal and a detection terminal, the first terminal of which is coupled to the first terminal of the first dimming circuit, and the second terminal of which is coupled to the common potential for determining the potential output by the detection end of the impedance detection circuit according to the impedance between the first end of the impedance detection circuit and the second end of the impedance detection circuit; 一第二阻抗侦测电路，包括第一端、第二端与侦测端，其第一端耦接该第二调光电路的第一端，其第二端耦接该共同电位，用以根据该阻抗侦测电路的第一端与该阻抗侦测电路的第二端之间的阻抗决定该阻抗侦测电路的侦测端所输出的电位；以及A second impedance detection circuit, including a first terminal, a second terminal and a detection terminal, the first terminal of which is coupled to the first terminal of the second dimming circuit, and the second terminal of which is coupled to the common potential for determining the potential output by the detection end of the impedance detection circuit according to the impedance between the first end of the impedance detection circuit and the second end of the impedance detection circuit; and 一反馈电压控制电路，其输入端耦接该第一阻抗侦测电路的侦测端以及该第二阻抗侦测电路的侦测端，其输出端，用以根据该第一阻抗侦测电路的侦测端以及该第二阻抗侦测电路的侦测端所输出的电位，控制该反馈信号的电压大小。A feedback voltage control circuit, the input end of which is coupled to the detection end of the first impedance detection circuit and the detection end of the second impedance detection circuit, and its output end is used to The potentials output by the detection terminal and the detection terminal of the second impedance detection circuit control the voltage of the feedback signal. 17.如权利要求16所述的光源驱动电路，其特征在于，17. The light source driving circuit according to claim 16, characterized in that, 该第一阻抗侦测电路包括：一第一阻抗元件，其一端为该第一阻抗侦测电路的第一端；一第二阻抗元件，其一端耦接该第一阻抗元件的另一端，其另一端耦接该共同电位；以及一第一二极管，其阳极耦接该第一阻抗元件的另一端，其阴极耦接该第一阻抗侦测电路的侦测端，The first impedance detection circuit includes: a first impedance element, one end of which is the first end of the first impedance detection circuit; a second impedance element, one end of which is coupled to the other end of the first impedance element, and The other end is coupled to the common potential; and a first diode, the anode of which is coupled to the other end of the first impedance element, and the cathode of which is coupled to the detection end of the first impedance detection circuit, 该第二阻抗侦测电路包括：一第三阻抗元件，其一端为该第二阻抗侦测电路的第一端；一第四阻抗元件，其一端耦接该第三阻抗元件的另一端，其另一端耦接该共同电位；以及一第二二极管，其阳极耦接该第三阻抗元件的另一端，其阴极耦接该第二阻抗侦测电路的侦测端。The second impedance detection circuit includes: a third impedance element, one end of which is the first end of the second impedance detection circuit; a fourth impedance element, one end of which is coupled to the other end of the third impedance element, and The other end is coupled to the common potential; and a second diode, its anode is coupled to the other end of the third impedance element, and its cathode is coupled to the detection end of the second impedance detection circuit. 18.如权利要求16所述的光源驱动电路，其特征在于，该反馈电压控制电路包括：18. The light source driving circuit according to claim 16, wherein the feedback voltage control circuit comprises: 一运算放大器，其包括第一输入端、第二输入端以及输出端，其输出端耦接该电源电压供应电路的反馈端，其第一输入端耦接该第一阻抗侦测电路的侦测端以及该第二阻抗侦测电路的侦测端，其第二端耦接一参考电压。An operational amplifier, which includes a first input terminal, a second input terminal and an output terminal, the output terminal is coupled to the feedback terminal of the power supply voltage supply circuit, and the first input terminal is coupled to the detection of the first impedance detection circuit end and the detection end of the second impedance detection circuit, the second end of which is coupled to a reference voltage. 19.如权利要求18所述的光源驱动电路，其特征在于，该反馈电压控制电路还包括：19. The light source driving circuit according to claim 18, wherein the feedback voltage control circuit further comprises: 一第三二极管，其阴极耦接该运算放大器的输出端，其阳极耦接该电源电压供应电路的输出端。A third diode, its cathode is coupled to the output terminal of the operational amplifier, and its anode is coupled to the output terminal of the power supply voltage supply circuit. 20.如权利要求18所述的光源驱动电路，其特征在于，该反馈电压控制电路还包括：20. The light source driving circuit according to claim 18, wherein the feedback voltage control circuit further comprises: 一第四二极管，其阴极耦接该第三二极管的阳极，其阳极耦接该电源电压供应电路的反馈端。A fourth diode, the cathode of which is coupled to the anode of the third diode, and the anode of which is coupled to the feedback terminal of the power supply voltage supply circuit. 21.如权利要求20所述的光源驱动电路，其特征在于，该反馈电压控制电路还包括：21. The light source driving circuit according to claim 20, wherein the feedback voltage control circuit further comprises: 一第三阻抗元件，其一端耦接该第三二极管的阳极，其另一端耦接该电源电压供应电路的输出端。A third impedance element, one end of which is coupled to the anode of the third diode, and the other end of which is coupled to the output end of the power supply voltage supply circuit. 22.如权利要求16所述的光源驱动电路，其特征在于，该反馈电路还包括：22. The light source driving circuit according to claim 16, wherein the feedback circuit further comprises: 一输出电压反馈电路，耦接于该电源电压供应电路的输出端与该电源电压供应电路的反馈端之间，用以根据电源电压供应电路的输出电压决定该反馈电压的大小。An output voltage feedback circuit, coupled between the output terminal of the power supply circuit and the feedback terminal of the power supply circuit, is used to determine the magnitude of the feedback voltage according to the output voltage of the power supply circuit. 23.如权利要求22所述的光源驱动电路，其特征在于，该输出电压反馈电路包括：23. The light source driving circuit according to claim 22, wherein the output voltage feedback circuit comprises: 一第四阻抗元件，其一端耦接该电源电压供应电路的输出端，其另一端耦接该电源电压供应电路的反馈端；以及A fourth impedance element, one end of which is coupled to the output end of the power supply voltage supply circuit, and the other end of which is coupled to the feedback end of the power supply voltage supply circuit; and 一第五阻抗元件，其一端耦接该第四阻抗元件的另一端，其另一端耦接该共同电位。A fifth impedance element, one end of which is coupled to the other end of the fourth impedance element, and the other end of which is coupled to the common potential. 24.如权利要求15所述的光源驱动电路，其特征在于，该第二发光元件为一发光二极管，其阳极耦接该电源电压供应电路的输出端。24. The light source driving circuit as claimed in claim 15, wherein the second light-emitting element is a light-emitting diode, the anode of which is coupled to the output terminal of the power supply circuit. 25.如权利要求15所述的光源驱动电路，其特征在于，该第二发光元件为多个发光二极管，该些发光二极管以阳极耦接阴极的方式串接，其中第一个发光二极管的阳极耦接该电源电压供应电路的输出端。25. The light source driving circuit according to claim 15, wherein the second light-emitting element is a plurality of light-emitting diodes, and the light-emitting diodes are connected in series in a manner that the anode is coupled to the cathode, wherein the anode of the first light-emitting diode coupled to the output terminal of the power voltage supply circuit.
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