WO2017049815A1 - 一种电视背光驱动装置及其驱动方法 - Google Patents

一种电视背光驱动装置及其驱动方法 Download PDF

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Publication number
WO2017049815A1
WO2017049815A1 PCT/CN2016/070267 CN2016070267W WO2017049815A1 WO 2017049815 A1 WO2017049815 A1 WO 2017049815A1 CN 2016070267 W CN2016070267 W CN 2016070267W WO 2017049815 A1 WO2017049815 A1 WO 2017049815A1
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WIPO (PCT)
Prior art keywords
current
backlight
control circuit
voltage
led
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PCT/CN2016/070267
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English (en)
French (fr)
Inventor
胡向峰
曾超
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深圳创维－Rgb电子有限公司
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Priority to AU2016269550A priority Critical patent/AU2016269550B2/en
Priority to US15/323,955 priority patent/US9936554B2/en
Publication of WO2017049815A1 publication Critical patent/WO2017049815A1/zh

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/382—Switched mode power supply [SMPS] with galvanic isolation between input and output
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/63—Generation or supply of power specially adapted for television receivers
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/14—Controlling the intensity of the light using electrical feedback from LEDs or from LED modules
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/20—Controlling the colour of the light
    • H05B45/24—Controlling the colour of the light using electrical feedback from LEDs or from LED modules
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/064—Adjustment of display parameters for control of overall brightness by time modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/14—Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/145—Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light originating from the display screen

Definitions

  • the present invention relates to the field of switching power supplies, and in particular, to a television backlight driving device and a driving method thereof.
  • the LED backlight driving adopts a constant current driving source.
  • the existing backlight driving scheme is to convert the DC output through the AC-DC module, and then the DC-DC module is stepped down or boosted to ensure the constant current output of the LED strip. Since the two-stage conversion processing (ie, AC to DC, and then DC to DC) is required from the AC input to the LED strip, the conversion processing efficiency is low. At the same time, the DC-DC processing section requires power devices (power switching circuits and control circuits) of the corresponding topology, resulting in higher costs.
  • an object of the present invention is to provide a television backlight driving device and a driving method thereof, which solve the problem that the prior backlight driving requires two stages of conversion processing, resulting in low efficiency.
  • a TV backlight driving device is connected to an LED light bar, wherein the TV backlight driving device comprises: an AC-DC module and an LED driving module;
  • the AC-DC module converts the input AC mains power into a DC voltage to supply power to the backlight LED strip.
  • the LED driving module determines that the detection current is greater than the preset current and is less than the first threshold, the duty is adjusted.
  • the LED drive module feeds the detection current back to the AC-DC module when the detection current is greater than the first threshold or less than the preset current; the AC-DC module controls the magnitude of the DC voltage according to the detection current.
  • the AC-DC module includes a main control circuit, a conversion circuit, an output circuit, and a second feedback circuit;
  • the main control circuit transmits the input AC mains power to the conversion circuit for voltage conversion, and the second feedback circuit regulates the converted voltage, and the output circuit filters and outputs the DC voltage to supply the backlight LED strip;
  • the second feedback circuit generates a corresponding control signal to the main control circuit according to the detection current fed back by the LED driving module, and the main control circuit adjusts the magnitude of the DC voltage according to the control signal.
  • the LED driving module includes a dimming switch, a first feedback circuit, and a backlight control circuit;
  • the backlight control circuit controls an on-off state of the dimmer switch to adjust a current flowing through the LED strip, and the first feedback circuit feeds back the detection voltage to the backlight control circuit, and the backlight control circuit calculates the current flow of the LED lamp according to the detected voltage.
  • the magnitude of the detected current of the strip
  • the backlight control circuit determines that the detected current is greater than the preset current and is less than the first threshold, adjusting the duty ratio of the dimmer switch to reduce the current flowing through the LED strip;
  • the detection current is fed back to the second feedback circuit.
  • the second feedback circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, and an optocoupler; one end of the first resistor is connected to the third resistor One end and an output circuit; the other end of the first resistor is connected to the backlight control circuit, and is also grounded through the second resistor, and is also connected to one end of the fourth resistor through the first capacitor; the other end of the third resistor is connected to the anode of the optocoupler. The other end of the fourth resistor is connected to the cathode of the optocoupler and the backlight control circuit.
  • the collector of the optocoupler is connected to the main control circuit, and the emitter of the optocoupler is grounded.
  • a driving method of the television backlight driving device comprising:
  • the AC-DC module converts the input AC mains into a DC voltage to power the LED strips of the backlight
  • the LED driving module determines that the detection current is greater than the preset current and is less than the first threshold, the LED current constant current output is controlled by PWM dimming; when the detection current is greater than the first threshold or less than the preset current, the LED driving module detects the current feedback.
  • the AC-DC module To the AC-DC module;
  • the AC-DC module controls the output of the DC voltage according to the detection current to make the LED current constant current output.
  • the AC-DC module converts the input AC mains power into a DC voltage to supply power to the LED strip of the backlight.
  • the main control circuit transmits the input AC mains power to the conversion circuit for voltage conversion
  • the second feedback circuit regulates the converted voltage, and then the output circuit filters and outputs a DC voltage to supply power to the LED strip of the backlight;
  • the backlight control circuit controls the duty cycle of the dimmer switch to be 100%.
  • the LED driving module determines that the detection current is greater than the preset current and is less than the first threshold, the LED current constant current output is controlled by PWM dimming; when the detection current is greater than the first threshold or less than the pre- When the current is set, the step of the LED driving module feeding back the detection current to the AC-DC module specifically includes:
  • the first feedback circuit feeds back the detection voltage to the backlight control circuit, and the backlight control circuit calculates the current of the detection current flowing through the LED strip according to the detected voltage;
  • the backlight control circuit determines that the detection current is greater than the preset current and is less than the first threshold, adjusting the duty ratio of the dimming switch to adjust the detection current;
  • the detection current is fed back to the second feedback circuit.
  • the step of the AC-DC module controlling the output of the DC voltage according to the detection current to make the LED current constant current output specifically includes:
  • the second feedback circuit generates a corresponding control signal to the main control circuit according to the detected current
  • the main control circuit adjusts the magnitude of the DC voltage according to the control signal.
  • the step of adjusting the duty ratio of the dimming switch to adjust the detection current specifically includes:
  • the backlight control circuit determines that the detection current is greater than the preset current and is less than the first threshold, the backlight control circuit reduces the duty ratio of the dimming switch;
  • the first feedback circuit feeds back the current detection voltage to the backlight control circuit, and the backlight control circuit determines whether the detection current is greater than the preset current and is less than the first threshold;
  • the backlight control circuit continues to reduce the duty ratio of the dimming switch, obtain the current detection voltage, and determine until the duty ratio reaches a minimum value;
  • the backlight control circuit increases the duty ratio of the dimming switch, continues to acquire the current detection voltage, and judges until the duty ratio reaches 100%;
  • the detection current is equal to the preset current, continue to acquire the current detection voltage and judge.
  • the television backlight driving device and the driving method thereof are provided.
  • the AC-DC module converts the input AC mains power into a DC voltage to supply power to the LED strip of the backlight;
  • the backlight driving method saves the system cost of the power supply and improves the system efficiency; when the LED driving module determines that the detection current is greater than the preset current and is less than the first threshold, the duty ratio is adjusted.
  • the LED driving module feeds back the detection current to the AC-DC module; the AC-DC module controls the magnitude of the DC voltage according to the detection current; different adjustments
  • the method can save power consumption and achieve the effect of stable current output; the circuit structure is simple and the reliability of the system is high.
  • FIG. 1 is a structural block diagram of a conventional LED backlight driving power supply
  • FIG. 2 is a structural block diagram of a television backlight driving device according to an embodiment of the present invention.
  • FIG. 3 is a circuit diagram of a television backlight driving device according to an embodiment of the present invention.
  • FIG. 4 is a flowchart of a method for driving a television backlight according to an embodiment of the present invention
  • FIG. 5 is a flowchart of a method of step S100 in a method for driving a television backlight according to an embodiment of the present invention
  • FIG. 6 is a flowchart of a method of step S200 in a method for driving a television backlight according to an embodiment of the present invention
  • FIG. 7 is a flowchart of a method of step S300 in a method for driving a television backlight according to an embodiment of the present invention
  • FIG. 8 is a flowchart of a method for applying an embodiment of a television backlight driving method according to an embodiment of the present invention.
  • the invention provides a television backlight driving device and a driving method thereof.
  • the television backlight driving device directly drives an LED backlight module through a transformer output winding, and does not need to undergo secondary boosting or stepping down to drive the backlight strip.
  • a television backlight driving device provided by the present invention includes an AC-DC module 10 and an LED driving module 20 connected thereto.
  • the input AC mains (AC) is directly converted into a DC voltage V LED through the AC-DC module 10 to supply power to the LED strip of the backlight.
  • the LED driving module 20 determines that the detection current is greater than the preset current and is less than the first threshold, the LED current constant current output is controlled by adjusting the duty ratio; when the detection current is greater than (or equal to) the first threshold or less than the preset current, the LED The drive module 20 feeds back the sense current to the AC-DC module 10.
  • the AC-DC module 10 controls the magnitude of the DC voltage V LED according to the detected current in order to maintain the stability of the constant current. Since the present embodiment does not need to maintain the constant current output characteristic of the LED lamp by the control of the existing constant current power loop, the secondary processing of the DC-DC power loop can be omitted.
  • the AC-DC module 10 includes a main control circuit 101, a conversion circuit 102, an output circuit 103, and a second feedback circuit 104.
  • the LED driving module 20 includes a dimming switch 201, a first feedback circuit 202, and a backlight control circuit 203.
  • the main control circuit 101 transmits the input AC mains power to the conversion circuit 102 for voltage conversion, and the second feedback circuit 104 regulates the converted voltage, and then the output circuit 103 filters and outputs the DC voltage to the backlight LED strip. powered by.
  • the backlight control circuit 203 controls the on-off state of the dimming switch 201 to adjust the magnitude of the current flowing through the LED strip.
  • the first feedback circuit 202 feeds back a detection voltage to the backlight control circuit 203 according to the magnitude of the current flowing through the LED strip.
  • the backlight control circuit 203 can calculate the magnitude of the actual detected current currently flowing through the LED strip based on the detected voltage.
  • the backlight control circuit 203 compares the detected current with a preset current. When the detection current is greater than the preset current and less than the first threshold, the backlight control circuit 203 adjusts the dimmer switch The duty cycle of 201 is to reduce the current flowing through the LED strip. When it is determined that the detection current is greater than the first threshold or less than the preset current, the adjustment of the dimming switch 201 will not meet the constant current requirement. At this time, the backlight control circuit 203 feeds back the detection current to the second feedback circuit 104. The second feedback circuit 104 generates a corresponding control signal to the main control circuit 101 according to the detected current, and the main control circuit 101 adjusts the magnitude of the DC voltage according to the control signal to achieve the effect of the LED constant current output.
  • the lamp bar current is adjusted by changing the duty ratio of the PWM dimming switch (ie, the dimming switch) when the current fluctuation is small.
  • the PWM dimming switch ie, the dimming switch
  • the screen voltage difference is large, simply relying on the PWM dimmer switch to adjust the light bar current will cause the temperature of the PWM dimming switch tube to be high, and the voltage withstand voltage of the PWM dimming switch tube is relatively high.
  • the common PWM dimming switch tube under high temperature and high voltage will be damaged, and the dedicated PWM dimming switch tube is costly and will increase the power consumption of the entire device. Therefore, when the PWM dimmer switch is not sufficient for regulation, it is also necessary to feed back to the primary (ie, by the AC-DC module) to reduce the output of the DC voltage.
  • the conversion circuit 102 includes a first switch tube S1, a second switch tube S2, and a transformer T.
  • the drain and the gate of the first switch tube S1 are connected to the main control circuit 101, and the first switch tube S1.
  • the source is connected to the drain of the second switch S2 and the same end of the first primary winding L1 of the transformer T.
  • the gate and source of the second switch S2 are connected to the main control circuit 101, and the source of the second switch S2 Also connected to one end of the second primary winding L2 of the transformer T, the first primary winding L1 is connected to the other end of the second primary winding L2; the same name end and the different end of the first secondary winding L3 of the transformer T, The same-named end and the different-named end of the second secondary winding L4 are connected to the conversion circuit 103.
  • the conversion circuit 103 includes a first diode D1, a second diode D2, and a filter capacitor Cr; the anode of the first diode D1 is connected to the same end of the first secondary winding L3; the first diode The cathode of D1 is connected to the cathode of the second diode D2, the second feedback circuit 104, one end of the filter capacitor Cr and the anode of the LED strip; the anode of the second diode D2 is connected to the second secondary winding L4. At the opposite end, the other end of the filter capacitor Cr is connected to the different end of the first secondary winding L3, the end of the second name of the second secondary winding L4, and the ground.
  • the second feedback circuit 104 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, and an optocoupler OP.
  • One end of the first resistor R1 is connected to the third resistor R3.
  • the resistance values of the first resistor R1 and the second resistor R2 determine the magnitude of the DC voltage V LED , and the voltage output from the cathode of the first diode D1 is divided by the first resistor R1 and the second resistor R2, which is equivalent to The DC voltage V LED stabilizes the output to a preset value.
  • the dimmer switch 201 includes a transistor Q1.
  • the base of the transistor Q1 is connected to the backlight control circuit 203.
  • the collector of the transistor Q1 is connected to the cathode of the LED strip.
  • the emitter of the transistor Q1 is connected to the first feedback circuit 202.
  • the first feedback circuit 202 includes a sampling resistor Rs.
  • One end of the sampling resistor Rs is connected to the emitter of the transistor Q1 and the backlight control circuit 203, and the other end of the sampling resistor Rs is grounded.
  • One end of the sampling resistor Rs collects the detection voltage and transmits it to the backlight control circuit 203.
  • the backlight control circuit 203 is based on the inspection
  • the current and the current flowing through the LED strip can be calculated by measuring the resistance of the voltage and the sampling resistor Rs.
  • a preset current (eg, 100 mA) is pre-stored in the backlight control circuit 203.
  • the LED light bar is increased, and the multi-channel first feedback circuit and the multi-channel dimming switch are added correspondingly, and the working principle is the same. That is to say, the number of transistors and the number of sampling resistors are equal to the number of LED strips, and the corresponding connections are shown in FIG.
  • the embodiment of the present invention further provides a driving method of the television backlight driving device.
  • the driving method includes:
  • the AC-DC module converts the input AC mains power into a DC voltage to supply power to the LED strip of the backlight;
  • the LED driving module determines that the detection current is greater than the preset current and is less than the first threshold, the LED current constant current output is controlled by PWM dimming; when the detection current is greater than the first threshold or less than the preset current, the LED driving module detects Current feedback
  • the S300 and AC-DC modules control the output DC voltage according to the detection current to make the LED current constant current output.
  • a system initialization step is further included, that is, the voltage range corresponding to the rated current of the light bar according to the light bar specification is 60V-80V.
  • the step S100 specifically includes:
  • the main control circuit transmits the input AC mains power to the conversion circuit for voltage conversion.
  • S102 The second feedback circuit regulates the converted voltage, and then outputs an output DC voltage to the LED strip of the backlight.
  • the DC voltage V LED obtained after voltage stabilization is 70V, which is determined by the resistance values of the first resistor R1 and the second resistor R2. In the subsequent work, the actual DC voltage V LED will constantly change.
  • the backlight control circuit controls the duty ratio of the dimming switch to be 100%.
  • the transistor Q1 is first set to be fully conductive, and the following state will appear.
  • the post-judgment processing is performed here by step S200.
  • step S200 specifically includes:
  • the first feedback circuit feeds back the detection voltage to the backlight control circuit, and the backlight control circuit calculates the current of the detection current flowing through the LED light bar according to the detected voltage. It needs to be calculated in conjunction with the resistance of the sampling resistor Rs.
  • This step is a processing method for the above state 3.
  • the duty ratio is adjusted to 100% in the above steps based on the duty ratio, and the duty ratio can be increased only after the duty ratio is subsequently adjusted.
  • the corresponding detection current is small, and when the duty ratio is increased, the corresponding detection current is increased.
  • the detection current is greater than the preset current and less than the first threshold, indicating that the detection current is slightly larger than the preset current, and can be adjusted by the duty cycle. If it is too large, that is, greater than or equal to the first threshold, the transistor Q1 cannot reduce the detection current to the required value, and needs to be adjusted by the AC-DC module. After each adjustment, the current detection current is collected once to continue the judgment.
  • the backlight control circuit determines that the detection current is greater than the preset current and is less than the first threshold, it indicates that the detection current is slightly larger than the preset current. At this time, the backlight control circuit reduces the duty ratio of the dimming switch, thereby reducing the detection current.
  • the duty ratio is reduced by 80% to 100%.
  • the minimum value can be set to 50% (the voltage withstand voltage of the transistor Q1 is higher and the cost is higher), that is, the range is 50% to 100%.
  • This embodiment does not limit the minimum value of the duty ratio.
  • the minimum value is 80%, the power consumption of the circuit is the smallest, and the voltage withstand voltage requirement of the transistor Q1 is small, and the cost is also saved.
  • the duty ratio is reduced, it can be gradually reduced to 80% according to the preset schedule. Such as every 5% reduction.
  • the first feedback circuit feeds back the current detection voltage to the backlight control circuit, and the backlight control circuit determines whether the detection current is greater than the preset current and is less than the first threshold.
  • the backlight control circuit continues to reduce the duty cycle of the dimmer switch, obtains the current detected voltage, and determines until the duty ratio reaches a minimum value of 80%.
  • the detection current is made smaller than the preset current (slightly small, that is, the detection current is less than the preset current is greater than the second threshold), and the adjustment can be increased by the backlight control circuit.
  • the duty cycle of the optical switch causes the sense current to rise.
  • the first feedback circuit then continues to transmit the collected detection current to the backlight control circuit for determination. As long as the duty ratio is in the range of 80% to 100%, and the detection current is greater than the preset current and less than the first threshold, the detection current can be changed by adjusting the duty ratio.
  • the first threshold is set to 0.2V, which is very close to the preset current.
  • the dimming switch ie, the transistor Q1
  • the adjustment of the AC-DC module is step S300.
  • the detection current is fed back to the second feedback circuit.
  • step S300 specifically includes:
  • the second feedback circuit generates a corresponding control signal according to the detected current to the main control circuit.
  • the main control circuit adjusts the magnitude of the DC voltage according to the control signal.
  • the main control circuit increases the DC voltage according to the control signal with a lower voltage to increase the detection current.
  • the main control circuit reduces the DC voltage according to the control signal with a large voltage to reduce the detection current.
  • the driving method of the television backlight driving device is specifically as follows:
  • AC mains input When power is on, AC mains input. Specifically: AC mains input main control circuit.
  • the main control circuit transmits the input AC mains power to the conversion circuit for voltage conversion.
  • DC voltage output supplies power to the LED strip.
  • the second feedback circuit regulates the converted voltage, and then the output circuit filters and outputs a DC voltage to supply power to the LED strip of the backlight.
  • the duty ratio of the control dimmer switch is 100%.
  • step S5. Determine whether the detection current is greater than the preset current: if yes, execute step S6, otherwise perform step S12.
  • step S6 after returning the duty cycle, returning to step S5, when the duty ratio is reduced to 80%, step S7 is performed.
  • step S7 Determine whether the detection current is greater than the preset current: if yes, go to step S17, otherwise go to step 8.
  • step S9 Determine whether the detection current is greater than the preset current: if yes, execute step S10, otherwise return to step 8.
  • step S11 Determine whether the detection current is greater than the preset current: if yes, return to step S10, otherwise return to step 9.
  • step S12 Determine whether the detection current is less than the preset current: if yes, execute step S13; otherwise, the detection current is equal to the preset current, and return to step 5 to continue the determination.
  • step S14 Determine whether the detection current is less than the preset current: if yes, return to step S13, otherwise perform step S15.
  • step S16 Determine whether the detection current is less than the preset current: if yes, return to step S13, otherwise return to step S15.
  • step S18 Determine whether the detection current is less than the preset current: if yes, execute step S19, otherwise return to step S17.
  • step S20 Determine whether the detection current is less than the preset current: if yes, execute step S19, otherwise return to step S17.
  • steps S8 to S11, S13 to S16, and S17 to S20 are three sets of steps that are continuously cycled. By repeating the adjustment in this way, a stable output of the DC voltage can be achieved. When the power is off, exit the above cycle.
  • the television backlight driving device and the driving method thereof provided by the invention have high system efficiency, and compared with the conventional backlight driving method, the DC voltage is directly output from the AC-DC module without performing secondary DC-DC processing.
  • the backlight is powered; at the same time, according to the detection current and the preset current, the corresponding duty ratio is adjusted or returned to the AC-DC module for adjustment, which can save power consumption and achieve stable current output; since directly from AC-DC
  • the module is provided for backlight driving, and the DC-DC module saves part of the power device compared with the prior art, thereby saving the system cost of the power supply; the circuit structure is simple, and the reliability of the system is high.

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  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
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  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

一种电视背光驱动装置及其驱动方法，所述电视背光驱动装置包括：AC-DC模块（10）和LED驱动模块（20）；上电时，所述AC-DC模块（10）将输入的交流市电转换成直流电压给背光的LED灯条供电；与现有背光驱动方式相比不用进行二次DC-DC处理，节省了电源的系统成本，提高了系统效率；当LED驱动模块（20）判断检测电流大于预设电流且小于第一阈值时，通过调节占空比控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块（20）将检测电流反馈给AC-DC模块（10）；AC-DC模块（10）根据检测电流控制直流电压的大小；不同的调节方法既能节省功耗，又能达到稳定电流输出的效果；其电路架构简单，系统的可靠性高。

Description

一种电视背光驱动装置及其驱动方法 技术领域
本发明涉及开关电源技术领域，特别涉及一种电视背光驱动装置及其驱动方法。
背景技术
由于LED灯属于恒流工作状态，LED灯电流大小恒定时，其电压可能存在一定的偏差，故在传统的LED背光驱动电源中，LED背光的驱动都采用的是恒流驱动源。如图1所示，现有的背光驱动方案都是通过AC-DC模块进行转换后DC输出，再经过DC-DC模块的降压或者升压来保证LED灯条的恒流输出。由于从交流输入到LED灯条需要经过两级的变换处理(即先AC转DC，再DC转DC)，导致变换处理效率低。同时，DC-DC处理部分需要相应拓扑的功率器件(功率开关电路和控制电路)，导致成本较高。
因此，现有技术还有待于改进和发展。
发明内容
鉴于上述现有技术的不足之处，本发明的目的在于提供一种电视背光驱动装置及其驱动方法，以解决现有背光驱动需经过两级的变换处理导致效率低的问题。
为了达到上述目的，本发明采取了以下技术方案：
一种电视背光驱动装置，与LED灯条连接，其中，所述电视背光驱动装置包括：AC-DC模块和LED驱动模块；
上电时，所述AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电，当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过调节占空比控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块；AC-DC模块根据检测电流控制直流电压的大小。
所述的电视背光驱动装置中，所述AC-DC模块包括主控制电路、转换电路、输出电路和第二反馈电路；
所述主控制电路将输入交流市电传输给转换电路进行电压转换，第二反馈电路对转换后的电压进行稳压后、由输出电路滤波输出直流电压给背光的LED灯条供电；及
第二反馈电路根据LED驱动模块反馈的检测电流生成对应的控制信号给主控制电路，主控制电路根据控制信号调节直流电压的大小。
所述的电视背光驱动装置中，所述LED驱动模块包括调光开关、第一反馈电路和背光控制电路；
所述背光控制电路控制调光开关的通断状态以调节流过LED灯条的电流大小，第一反馈电路反馈检测电压给背光控制电路，背光控制电路根据该检测电压计算出当前流过LED灯条的检测电流的大小；
当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比以降低流过LED灯条的电流；
当背光控制电路判断检测电流大于第一阈值或小于预设电流时，将检测电流反馈给第二反馈电路。
所述的电视背光驱动装置中，所述第二反馈电路包括第一电阻、第二电阻、第三电阻、第四电阻、第一电容和光耦；所述第一电阻的一端连接第三电阻的一端和输出电路；第一电阻的另一端连接背光控制电路、还通过第二电阻接地、也通过第一电容连接第四电阻的一端；所述第三电阻的另一端连接光耦的阳极，所述第四电阻的另一端连接光耦的阴极和背光控制电路，光耦的集电极连接主控制电路，光耦的发射极接地。
一种所述电视背光驱动装置的驱动方法，其包括：
上电时，AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电；
当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过PWM调光控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块；
AC-DC模块根据检测电流控制输出的直流电压的大小，使LED电流恒流输出。
所述的电视背光驱动方法中，所述上电时，AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电的步骤具体包 括：
主控制电路将输入交流市电传输给转换电路进行电压转换；
第二反馈电路对转换后的电压进行稳压后、再由输出电路滤波输出直流电压给背光的LED灯条供电；
背光控制电路控制调光开关的占空比为100％。
所述的电视背光驱动方法中，所述当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过PWM调光控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块的步骤具体包括：
第一反馈电路反馈检测电压给背光控制电路，背光控制电路据检测电压计算出当前流过LED灯条的检测电流的大小；
当背光控制电路判断检测电流与预设电流相等时，不处理继续判断；
当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比来调节检测电流；
当背光控制电路判断检测电流大于等于第一阈值或小于预设电流时，将检测电流反馈给第二反馈电路。
所述的电视背光驱动方法中，所述AC-DC模块根据检测电流控制输出的直流电压的大小，使LED电流恒流输出的步骤具体包括：
第二反馈电路根据所述检测电流生成对应的控制信号给主控制电路；
主控制电路根据控制信号调节直流电压的大小。
所述的电视背光驱动方法中，所述当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比来调节检测电流的步骤具体包括：
当背光控制电路判断检测电流大于预设电流且小于第一阈值时，背光控制电路减小调光开关的占空比；
第一反馈电路反馈当前的检测电压给背光控制电路，背光控制电路判断检测电流是否大于预设电流且小于第一阈值；
若检测电流大于预设电流且小于第一阈值，则背光控制电路继续减小调光开关的占空比、获取当前的检测电压并判断，直至占空比达到最小值；
若检测电流小于预设电流，则背光控制电路增大调光开关的占空比、继续获取当前的检测电压并判断，直至占空比达到100％；
若检测电流等于预设电流，继续获取当前的检测电压并判断。
相较于现有技术，本发明提供的电视背光驱动装置及其驱动方法，上电时，所述AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电；与现有背光驱动方式相比不用进行二次DC-DC处理，节省了电源的系统成本，提高了系统效率；当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过调节占空比控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块；AC-DC模块根据检测电流控制直流电压的大小；不同的调节方法即能节省功耗，又能达到稳定电流输出的效果；其电路架构简单，系统的可靠性高。
附图说明
图1为现有的LED背光驱动电源的结构框图；
图2为本发明实施例提供的电视背光驱动装置的结构框图；
图3为本发明实施例提供的电视背光驱动装置的电路图；
图4为本发明实施例提供的电视背光驱动方法流程图；
图5为本发明实施例提供的电视背光驱动方法中步骤S100的方法流程图；
图6为本发明实施例提供的电视背光驱动方法中步骤S200的方法流程图；
图7为本发明实施例提供的电视背光驱动方法中步骤S300的方法流程图；
图8为本发明实施例提供的电视背光驱动方法应用实施例的方法流程图。
具体实施方式
本发明提供一种电视背光驱动装置及其驱动方法，所述电视背光驱动装置直接通过变压器输出绕组来驱动LED背光模组，无需经过二次的升压或者降压来驱动背光灯条。为使本发明的目的、技术方案及效果更加清楚、明确，以下参照附图并举实施例对本发明进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。
请参阅图1，本发明提供的电视背光驱动装置包括AC-DC模块10和与其连接的LED驱动模块20。上电时，直接通过所述AC-DC模块10将输入的交流市电(AC)转换成直流电压VLED给背光的LED灯条供电。当LED驱动模块20判断检测电流大于预设电流且小于第一阈值时，通过调节占空比控制LED电流恒流输出；当检测电流大于(或等于)第一阈值或小于预设电流时，LED驱动模块20将检测电流反馈给AC-DC模块10。AC-DC模块10根据检测电流控制直流电压VLED的大小，以便维持恒流的稳定。由于本实施例无需通过现有恒流功率回路的控制来维持LED灯的恒流输出特性，可以省略DC-DC功率回路的二次处理。
其中，所述AC-DC模块10包括主控制电路101、转换电路102、输出电路103和第二反馈电路104。所述LED驱动模块20包括调光开关201、第一反馈电路202和背光控制电路203。
所述主控制电路101将输入交流市电传输给转换电路102进行电压转换，第二反馈电路104对转换后的电压进行稳压后、再由输出电路103滤波输出直流电压给背光的LED灯条供电。背光控制电路203控制调光开关201的通断状态以调节流过LED灯条的电流大小。所述第一反馈电路202根据流过LED灯条的电流大小反馈一个检测电压给背光控制电路203。背光控制电路203根据该检测电压即可计算出当前流过LED灯条的实际的检测电流的大小。
背光控制电路203将检测电流比预设电流进行比较。当检测电流大于预设电流且小于第一阈值时，背光控制电路203调节调光开关 201的占空比以降低流过LED灯条的电流。当判断检测电流大于第一阈值或小于预设电流时，调光开关201的调节将无法满足恒流要求，此时，背光控制电路203将检测电流反馈给第二反馈电路104。第二反馈电路104根据所述检测电流生成对应的控制信号给主控制电路101，主控制电路101根据控制信号调节直流电压的大小，以实现LED恒流输出的效果。
本实施例在电流波动较小时通过改变PWM调光开关(即调光开关)的占空比来调节灯条电流。当屏体电压相差较大时，单纯地依靠PWM调光开关来调节灯条电流，会导致PWM调光开关管的温度很高，对PWM调光开关管的耐压要求较高。高温高压下常见的PWM调光开关管会损坏，而专用的PWM调光开关管成本高，且会增加整个装置的功耗。因此，当PWM调光开关不足以调节时，还需要反馈至初级(即由AC-DC模块)来降低直流电压的输出。
本实施例中，所述转换电路102包括第一开关管S1、第二开关管S2和变压器T；所述第一开关管S1的漏极和栅极连接主控制电路101，第一开关管S1的源极连接第二开关管S2的漏极和变压器T的第一初级绕组L1的同名端，第二开关管S2的栅极和源极连接主控制电路101，第二开关管S2的源极还连接变压器T的第二初级绕组L2的一端，所述第一初级绕组L1异名端连接第二初级绕组L2的另一端；变压器T的第一次级绕组L3的同名端和异名端，第二次级绕组L4的同名端和异名端均连接转换电路103。
所述转换电路103包括第一二极管D1、第二二极管D2和滤波电容Cr；所述第一二极管D1的正极连接第一次级绕组L3的同名端；第一二极管D1的负极连接第二二极管D2的负极、第二反馈电路104、滤波电容Cr的一端和LED灯条的正极+；所述第二二极管D2的正极连接第二次级绕组L4的异名端，滤波电容Cr的另一端连接第一次级绕组L3的异名端、第二次级绕组L4的同名端和地。
所述第二反馈电路104包括第一电阻R1、第二电阻R2、第三电阻R3、第四电阻R4、第一电容C1和光耦OP；所述第一电阻R1的一端连接第三电阻R3的一端和第一二极管D1的负极；第一电阻R1的另一端连接背光控制电路、还通过第二电阻R2接地、也通过第一电容C1连接第四电阻R4的一端；所述第三电阻R3的另一端连接光耦OP的阳极，所述第四电阻R4的另一端连接光耦OP的阴极和背光控制电路203，光耦OP的集电极连接主控制电路101，光耦OP的发射极接地。其中，第一电阻R1和第二电阻R2的阻值决定直流电压VLED的大小，第一二极管D1的负极输出的电压进过第一电阻R1和第二电阻R2分压，相当于使直流电压VLED稳定输出为一预设值。
所述调光开关201包括三极管Q1，所述三极管Q1的基极连接背光控制电路203，三极管Q1的集电极连接LED灯条的负极-，三极管Q1的发射极连接第一反馈电路202。所述第一反馈电路202包括采样电阻Rs，所述采样电阻Rs的一端连接三极管Q1的发射极和背光控制电路203，采样电阻Rs的另一端接地。采样电阻Rs的一端采集检测电压并传输给背光控制电路203。背光控制电路203根据检 测电压和采样电阻Rs的阻值即可计算出当前流过LED灯条的电流。背光控制电路203中预存有预设电流(如100mA),
本实施例中，多通道配屏时，LED灯条增加，则对应增加多路第一反馈电路和多路调光开关，其工作原理相同。也即是说，三极管的个数、采样电阻的个数与LED灯条的个数相等，且对应连接，如图3所示。
基于上述的电视背光驱动装置，本发明实施例还相应提供一种电视背光驱动装置的驱动方法。请同时参阅图3和图4，所述驱动方法包括：
S100、上电时，AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电；
S200、当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过PWM调光控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给
AC-DC模块；
S300、AC-DC模块根据检测电流控制输出的直流电压的大小，使LED电流恒流输出。
在所述步骤S100之前，还包括系统初始化步骤，即根据灯条规格书得到灯条额定电流下对应的电压范围为60V～80V。
如图5所示，所述步骤S100具体包括：
S101、主控制电路将输入交流市电传输给转换电路进行电压转换。
S102、第二反馈电路对转换后的电压进行稳压后、再由输出电路滤波输出直流电压给背光的LED灯条供电。
需要理解的时，上电初始时，稳压后得到的直流电压VLED为70V，由第一电阻R1和第二电阻R2的阻值决定。之后的工作中，实际的直流电压VLED会不断变化。
S103、背光控制电路控制调光开关的占空比为100％。该步骤将三极管Q1先设置为全导通，此时会出现如下状态，
1是实际LED灯条达到额定电流所需要的电压小于AC-DC模块输出的直流电压；表示在100％占空比的控制下，LED灯条实际的检测电流大于预设电流。大于又分为略大和较大。
2是实际LED灯条达到额定电流所需要的电压大于AC-DC模块输出的直流电压；表示在100％占空比的控制下，LED灯条实际的电流小于预设电流。
3是实际LED灯条达到额定电流所需要的电压等于AC-DC模块输出的直流电压，此时系统稳定不用调节。
此处通过步骤S200进行判断后处理。
如图6所示，所述步骤S200具体包括：
S201、第一反馈电路反馈检测电压给背光控制电路，背光控制电路据检测电压计算出当前流过LED灯条的检测电流的大小。需结合采样电阻Rs的阻值来计算。
S202、当背光控制电路判断检测电流与预设电流相等时，不处理继续判断。该步骤是针对上述状态3的处理方法。
S203、当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比来调节检测电流。
需要理解的是，基于占空比在上述步骤中已调节为100％，后续调节时只能减少占空比后再增加占空比。占空比变小则对应的检测电流变小，占空比变大则对应的检测电流变大。检测电流大于预设电流且小于第一阈值，表示检测电流比预设电流略大，可通过占空比来调节。若大太多，即大于或等于第一阈值，则三极管Q1无法将检测电流下降至需要值，需通过AC-DC模块来调节。每次调节后会在采集一次当前的检测电流以继续判断。
在所述步骤203中，若背光控制电路判断检测电流大于预设电流且小于第一阈值，表示检测电流比预设电流略大。此时，背光控制电路减小调光开关的占空比，即可降低检测电流。
本实施例中，占空比的减小范围为80％～100％。在具体实施时还可设置最小值为50％(对三极管Q1的耐压耐温要求较高，且成本较高)，即范围为50％～100％。本实施例对占空比的最小值不作限定。最小值为80％时，电路的功耗最小、且对三极管Q1的耐压耐温要求很小，还节省成本。占空比减小时可按预设进度逐渐减小至80％。如每隔5％减少一次。
每次减少占空比后继续判断检测电流是否大于预设电流且小于第一阈值。第一反馈电路反馈当前的检测电压给背光控制电路，背光控制电路判断检测电流是否大于预设电流且小于第一阈值。
若检测电流仍大于预设电流且小于第一阈值，则背光控制电路继续减小调光开关的占空比，获取当前的检测电压并判断，直至占空比达到最小值80％为止。
若占空比在80％～100％范围内减少时，使检测电流比预设电流小(略小，即检测电流小于预设电流大于第二阈值)，此时可通过背光控制电路增大调光开关的占空比使检测电流升高。之后第一反馈电路继续将采集到的检测电流传输给背光控制电路进行判断。只要占空比在80％～100％范围内，检测电流大于预设电流且小于第一阈值，均可通过调节占空比来改变检测电流。
若某次调节使检测电流与预设电流相等，则不处理。其中，所述第一阈值设置为0.2V，很接近预设电流。通过不断重复即可相当于维持流过LED灯的电流尽可能等于预设电流，从而达到恒流输出的效果。
若占空比调节至80％时，检测电流仍大于预设电流且小于第一阈值，调光开关(即三极管Q1)将无法完成调节，需将检测电流传输给AC-DC模块来调节。AC-DC模块的调节为步骤S300。
S204、当背光控制电路判断检测电流大于等于第一阈值或小于预设电流时，将检测电流反馈给第二反馈电路。
如图7所示，所述步骤S300具体包括：
S301、第二反馈电路根据所述检测电流生成对应的控制信号给主控制电路。
S302、主控制电路根据控制信号调节直流电压的大小。
若检测电流较小，则生成电压较低的控制信号，则主控制电路根据电压较低的控制信号将直流电压调大，以增大检测电流。同理，检测电流较大，则生成电压较大的控制信号，则主控制电路根据电压较大的控制信号将直流电压调小，以减小检测电流。
需要理解的是，上述步骤调节直流电压的大小时，是不断重复的。掉电时结束上述所有步骤，并对直流电压放电清零。
请一并参阅图2-图8，所述电视背光驱动装置的驱动方法具体为：
S1、上电时，交流市电输入。具体为：交流市电输入主控制电路。
S2、对交流市电进行电压转换。具体为：主控制电路将输入交流市电传输给转换电路进行电压转换。
S3、直流电压输出给LED灯条供电。具体为：第二反馈电路对转换后的电压进行稳压后、再由输出电路滤波输出直流电压给背光的LED灯条供电。
S4、控制调光开关的占空比为100％。
S5、判断检测电流是否大于预设电流：是则执行步骤S6，否则执行步骤S12。
S6、降低占空比后返回步骤S5，当占空比降为80％时，执行步骤S7.
S7、判断检测电流是否大于预设电流：是则执行步骤S17，否则执行步骤8。
S8、增大占空比。
S9、判断检测电流是否大于预设电流：是则执行步骤S10，否则返回步骤8。
S10、减小占空比。
S11、判断检测电流是否大于预设电流：是则返回步骤S10，否则返回步骤9。
S12、判断检测电流是否小于预设电流：是则执行步骤S13，否则检测电流与预设电流相等，返回步骤5继续判断。
S13、检测电流反馈给AC-DC模块控制直流电压升高。
S14、判断检测电流是否小于预设电流：是则返回步骤S13，否则执行步骤S15。
S15、检测电流反馈给AC-DC模块控制直流电压降低。
S16、判断检测电流是否小于预设电流：是则返回步骤S13，否则返回步骤S15。
S17、检测电流反馈给AC-DC模块控制直流电压降低。
S18、判断检测电流是否小于预设电流：是则执行步骤S19，否则返回步骤S17。
S19、检测电流反馈给AC-DC模块控制直流电压升高。
S20、判断检测电流是否小于预设电流：是则执行步骤S19，否则返回步骤S17。
需要理解的是，上述步骤S8～S11，S13～S16，S17～S20是三组不断循环的步骤。通过这样重复调整，即可实现直流电压的稳定输出。当掉电时，退出上述循环。
综上所述，本发明提供的电视背光驱动装置及其驱动方法，其系统效率高，与传统背光驱动方式相比，不用进行二次DC-DC处理，直接从AC-DC模块输出直流电压对背光供电；同时，根据检测电流与预设电流的大小比较对应选占空比调节或返回AC-DC模块调节，即能节省功耗，又能达到稳定电流输出的效果；由于直接从AC-DC模块供背光驱动，DC-DC模块较现有技术省去了部分功率器件，从而节省了电源的系统成本；其电路架构简单，系统的可靠性高。
可以理解的是，对本领域普通技术人员来说，可以根据本发明的技术方案及其发明构思加以等同替换或改变，而所有这些改变或替换都应属于本发明所附的权利要求的保护范围。

Claims (10)

  1. 一种电视背光驱动装置，与LED灯条连接，其特征在于，所述电视背光驱动装置包括：AC-DC模块和LED驱动模块；
    上电时，所述AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电，当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过调节占空比控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块；AC-DC模块根据检测电流控制直流电压的大小。
  2. 一种电视背光驱动装置，与LED灯条连接，其特征在于，所述电视背光驱动装置包括：AC-DC模块和LED驱动模块；
    上电时，所述AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电，当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过调节占空比控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块；AC-DC模块根据检测电流控制直流电压的大小；
    所述AC-DC模块包括主控制电路、转换电路、输出电路和第二反馈电路；
    所述主控制电路将输入交流市电传输给转换电路进行电压转换，第二反馈电路对转换后的电压进行稳压后、由输出电路滤波输出直流电压给背光的LED灯条供电；及
    第二反馈电路根据LED驱动模块反馈的检测电流生成对应的控制信号给主控制电路，主控制电路根据控制信号调节直流电压的大小。
  3. 根据权利要求2所述的电视背光驱动装置，其特征在于，所述LED驱动模块包括调光开关、第一反馈电路和背光控制电路；
    所述背光控制电路控制调光开关的通断状态以调节流过LED灯条的电流大小，第一反馈电路反馈检测电压给背光控制电路，背光控制电路根据该检测电压计算出当前流过LED灯条的检测电流的大小；
    当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比以降低流过LED灯条的电流；
    当背光控制电路判断检测电流大于第一阈值或小于预设电流时，将检测电流反馈给第二反馈电路。
  4. 根据权利要求2所述的电视背光驱动装置，其特征在于，所述第二反馈电路包括第一电阻、第二电阻、第三电阻、第四电阻、第一电容和光耦；所述第一电阻的一端连接第三电阻的一端和输出电路；第一电阻的另一端连接背光控制电路、还通过第二电阻接地、也通过第一电容连接第四电阻的一端；所述第三电阻的另一端连接光耦的阳极，所述第四电阻的另一端连接光耦的阴极和背光控制电路，光耦的集电极连接主控制电路，光耦的发射极接地。
  5. 根据权利要求3所述的电视背光驱动装置，其特征在于，所述第二反馈电路包括第一电阻、第二电阻、第三电阻、第四电阻、第一电容和光耦；所述第一电阻的一端连接第三电阻的一端和输出电路；第一电阻的另一端连接背光控制电路、还通过第二电阻接地、也通过第一电容连接第四电阻的一端；所述第三电阻的另一端连接光耦的阳 极，所述第四电阻的另一端连接光耦的阴极和背光控制电路，光耦的集电极连接主控制电路，光耦的发射极接地。
  6. 一种如权利要求1所述电视背光驱动装置的驱动方法，其特征在于，包括：
    上电时，AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电；
    当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过PWM调光控制LED电流恒流输出；当检测电流大于第一阈值或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块；
    AC-DC模块根据检测电流控制输出的直流电压的大小，使LED电流恒流输出。
  7. 根据权利要求6所述的电视背光驱动方法，其特征在于，所述上电时，AC-DC模块将输入的交流市电转换成直流电压给背光的LED灯条供电的步骤具体包括：
    主控制电路将输入交流市电传输给转换电路进行电压转换；
    第二反馈电路对转换后的电压进行稳压后、再由输出电路滤波输出直流电压给背光的LED灯条供电；
    背光控制电路控制调光开关的占空比为100％。
  8. 根据权利要求7所述的电视背光驱动方法，其特征在于，所述当LED驱动模块判断检测电流大于预设电流且小于第一阈值时，通过PWM调光控制LED电流恒流输出；当检测电流大于第一阈值 或小于预设电流时，LED驱动模块将检测电流反馈给AC-DC模块的步骤具体包括：
    第一反馈电路反馈检测电压给背光控制电路，背光控制电路据检测电压计算出当前流过LED灯条的检测电流的大小；
    当背光控制电路判断检测电流与预设电流相等时，不处理继续判断；
    当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比来调节检测电流；
    当背光控制电路判断检测电流大于等于第一阈值或小于预设电流时，将检测电流反馈给第二反馈电路。
  9. 根据权利要求6所述的电视背光驱动方法，其特征在于，所述AC-DC模块根据检测电流控制输出的直流电压的大小，使LED电流恒流输出的步骤具体包括：
    第二反馈电路根据所述检测电流生成对应的控制信号给主控制电路；
    主控制电路根据控制信号调节直流电压的大小。
  10. 根据权利要求8所述的电视背光驱动方法，其特征在于，所述当背光控制电路判断检测电流大于预设电流且小于第一阈值时，调节调光开关的占空比来调节检测电流的步骤具体包括：
    当背光控制电路判断检测电流大于预设电流且小于第一阈值时，背光控制电路减小调光开关的占空比；
    第一反馈电路反馈当前的检测电压给背光控制电路，背光控制电路判断检测电流是否大于预设电流且小于第一阈值；
    若检测电流大于预设电流且小于第一阈值，则背光控制电路继续减小调光开关的占空比、获取当前的检测电压并判断，直至占空比达到最小值；
    若检测电流小于预设电流，则背光控制电路增大调光开关的占空比、继续获取当前的检测电压并判断，直至占空比达到100％；
    若检测电流等于预设电流，继续获取当前的检测电压并判断。
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