LED drive circuit and display device

Abstract

The utility model discloses an LED driving circuit and a display device. The LED driving circuit comprises a rectification module; a flyback converter; a one-way energy storage module; a switch module; an energy storage module; a one-way conduction module; a first driving module; and a second driving module. According to the invention, the unidirectional energy storage module connected between the output terminal of the rectifier module and the tap of the primary coil stores energy when the switch module is switched on, and is limited by the unidirectional conduction module connected between the output terminal of the rectifier module and the energy storage module when the switch module is switched off, so that the stored energy is transmitted to the energy storage module; according to the driving circuit, the energy storage module is charged and discharged at high frequency, so that the waveforms of the input current and the input voltage are close to the same phase, the power factor is improved, harmonic waves are reduced, and compared with the harmonic waves reduced by adding a PFC (Power Factor Correction) circuit in the prior art, the circuit structure is simplified, the cost is reduced, and the reliability of the driving circuit is improved.

Description

Technical Field

[0001] The present application relates to the field of LED driving technology, and in particular to an LED driving circuit and a display device. Background Art

[0002] The main function of the LED driver circuit is to convert AC voltage into a constant current power supply, and at the same time match the voltage and current of the LED according to the requirements of the LED device. Due to the limitation of LED power level, in the scenario where multiple LEDs need to be driven at the same time, a dedicated driver circuit is usually required to light up the LED.

[0003] In the TV field, high-power LED drivers usually need to add a power factor correction (PFC) circuit to meet harmonic standards because the power exceeds 75W.

[0004] In the related art, high-power LED driving circuits generally use a PFC circuit, a flyback circuit, or an LLC resonant circuit consisting of two inductors and one capacitor combined with a buck-boost topology circuit. However, this type of driving circuit has a more complex structure and may have lower circuit reliability due to the large number of devices in the circuit. Utility Model Content

[0005] In view of the above problems, the present application provides an LED driving circuit and a display device to solve the above technical problems.

[0006] In a first aspect, the present application provides an LED driving circuit, which is used to drive a display board and a backlight LED light bar to work, and the LED driving circuit includes:

[0007] A rectifier module, used for receiving an AC voltage signal and provided with an output terminal for outputting a rectified voltage signal;

[0008] A flyback converter comprises a primary coil and a first secondary coil and a second secondary coil respectively coupled to the primary coil, wherein the primary coil is provided with a tap, the tap divides the primary coil into a first coil and a second coil, the first secondary coil is provided with an output terminal for outputting a first voltage signal, and the second secondary coil is provided with an output terminal for outputting a second voltage signal;

[0009] A unidirectional energy storage module, one end of which is connected to the output terminal of the rectifier module, and the other end is connected to the tap;

[0010] A switch module, wherein a first end of the switch module is connected to a terminal of the second coil that is different from the tap, a second end of the switch module is connected to a ground terminal, and a third end of the switch module is used to access a control signal, and the switch module is controlled to be turned on or off by the control signal;

[0011] An energy storage module, wherein a first end of the energy storage module is connected to a terminal of the first coil that is different from the tap, and a second end of the energy storage module is connected to a ground terminal;

[0012] A unidirectional conduction module, one end of which is connected to the output terminal of the rectifier module, and the other end of which is connected to the first end of the energy storage module;

[0013] A first driving module, connected to the output terminal of the first secondary coil, and used to drive the backlight LED light bar to work based on the first voltage signal;

[0014] The second driving module is connected to the output terminal of the second secondary coil and is used to drive the display board to work based on the second voltage signal.

[0015] In a possible implementation of the present application, the unidirectional energy storage module includes an energy storage diode and a first inductor, the anode of the energy storage diode is connected to the output terminal of the rectifier module, the cathode of the energy storage diode is connected to one end of the first inductor, and the other end of the first inductor is connected to the tap.

[0016] In a possible implementation of the present application, the unidirectional conduction module includes a bypass diode, an anode of the bypass diode is connected to the output terminal of the rectifier module, and a cathode of the bypass diode is connected to the first end of the energy storage module.

[0017] In a possible implementation of the present application, the first driving module includes a buck conversion control unit, a first controllable switch, a first unidirectional diode, a first energy storage inductor and a first energy storage capacitor;

[0018] The first end of the first controllable switch is connected to the step-down conversion control unit to access the first control signal, the second end of the first controllable switch is respectively connected to the anode of the first unidirectional diode and the first end of the first energy storage inductor, the third end of the first controllable switch is grounded, the cathode of the first unidirectional diode is respectively connected to the output terminal of the first secondary coil and the positive electrode of the first energy storage capacitor, the second end of the first energy storage inductor is connected to the negative electrode of the first energy storage capacitor, and the backlight LED light strip is connected in parallel with the first energy storage capacitor.

[0019] In a possible implementation of the present application, the buck conversion control unit is further connected to a first preset port of the display board to access the first switch control signal;

[0020] The buck conversion control unit is used to generate a first control signal according to the input first switch control signal to control the first controllable switch to be turned on or off.

[0021] In a possible implementation of the present application, the first driving module includes a boost conversion control unit, a second controllable switch, a second unidirectional diode, a second energy storage inductor and a second energy storage capacitor;

[0022] The first end of the second controllable switch is connected to the boost conversion control unit to access the second control signal, the second end of the second controllable switch is respectively connected to the second end of the second energy storage inductor and the anode of the second unidirectional diode, the third end of the second controllable switch is grounded, the first end of the second energy storage inductor is connected to the output terminal of the first secondary coil, the cathode of the second unidirectional diode is connected to the positive electrode of the second energy storage capacitor, the negative electrode of the second energy storage capacitor is grounded, and the backlight LED light strip is connected in parallel with the second energy storage capacitor.

[0023] In a possible implementation of the present application, the boost conversion control unit is further connected to a second preset port of the display board to access a second switch control signal;

[0024] The boost conversion control unit is used to generate a second control signal according to the connected second switch control signal to control the second controllable switch to be turned on or off.

[0025] In a possible implementation of the present application, the first driving module includes a sampling resistor, a first operational amplifier, a third unidirectional diode and a photocoupler;

[0026] The sampling resistor is connected in series with the backlight LED light strip and is connected to the input end of the first operational amplifier. The output end of the first operational amplifier is connected to the cathode of the third unidirectional diode. The anode of the third unidirectional diode is connected to the cathode of the light emitter of the photoelectric coupler. The anode of the light emitter of the photoelectric coupler is connected to the driving voltage signal. The light receiver of the photoelectric coupler is connected to the third end of the switch module through the control circuit.

[0027] In a possible implementation of the present application, the second driving module includes a third controllable switch, a third energy storage inductor, a third energy storage capacitor, a fourth unidirectional diode and a feedback control unit;

[0028] The first end of the third controllable switch is connected to the output end of the feedback control unit to access the feedback control signal, the second end of the third controllable switch is connected to the output terminal of the second secondary coil, the third end of the third controllable switch is respectively connected to the first end of the third energy storage inductor and the cathode of the fourth unidirectional diode, and the second end of the third energy storage inductor is respectively connected to the positive electrode of the third energy storage capacitor, the input end of the feedback control unit, the anode of the light emitter of the photoelectric coupler and the third preset port of the display board.

[0029] In a second aspect, the present application further provides a display device, which includes a device body and the LED driving circuit of the first aspect.

[0030] From the above content, it can be concluded that the present application has the following beneficial effects:

[0031] In the present application, a unidirectional energy storage module connected between the output terminal of the rectifier module and the tap of the primary coil is used to store energy when the switch module is turned on, and when the switch module is turned off, it is restricted by the unidirectional conduction module connected between the output terminal of the rectifier module and the energy storage module, and the stored energy is transferred to the energy storage module to charge it, so that the input current and the input voltage are close to the same phase, thereby improving the power factor and reducing harmonics. Compared with the related art of reducing harmonics by adding a PFC circuit, the circuit structure is simplified, the cost is reduced, and the reliability of the drive circuit is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 It is a structural schematic diagram of an LED driving circuit in the related art;

[0034] Figure 2 is a module schematic diagram of an LED driving circuit provided in an embodiment of the present application;

[0035] Figure 3 It is a schematic diagram of the flow direction of a loop current when the switch module provided in the embodiment of the present application is turned on;

[0036] Figure 4 It is a schematic diagram of the flow direction of a loop current when the switch module provided in the embodiment of the present application is disconnected;

[0037] Figure 5 is a structural schematic diagram of a unidirectional energy storage module provided in an embodiment of the present application;

[0038] Figure 6 is a structural schematic diagram of a first driving module provided in an embodiment of the present application;

[0039] Figure 7 is another structural schematic diagram of the first driving module provided in an embodiment of the present application;

[0040] Figure 8 It is another structural schematic diagram of the first driving module provided in the embodiment of the present application. DETAILED DESCRIPTION

[0041] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0042] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0043] In the embodiments of the present application, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0044] Moreover, the terms "comprises", "comprising" or any other variation thereof are intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such article or device. In the absence of more restrictions, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0045] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "example" or "for example" in the embodiments of the present application is not to be interpreted as being more preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0046] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.

[0047] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0048] Before introducing the LED driving circuit and display device of the present application, the relevant background information of the embodiments of the present application is first introduced.

[0049] In the TV field, high-power LED drivers usually need to add a power factor correction (PFC) circuit to meet harmonic standards because the power exceeds 75W. Figure 1 As shown, the LED driving circuit may include a bridge rectifier, a PFC module, an LLC resonant circuit / flyback circuit, an AC / DC converter, and a buck-boost topology circuit.

[0050] Among them, the bridge rectifier can rectify the input AC power Vacin and output the rectified voltage to the PFC module. After the rectified voltage is processed by the PFC module, LLC resonant circuit / flyback circuit, AC / DC converter and buck-boost topology circuit, the power supply voltage is obtained and flows into the LED light strip formed by n LEDs connected in series to drive the LED light strip to emit light.

[0051] However, the structure of this type of LED driving circuit is relatively complex, and since there are many devices in the circuit, the probability of device failure is relatively high, resulting in low circuit reliability.

[0052] Based on this, the embodiment of the present application provides an LED driving circuit and a display device. The LED driving circuit stores energy through a unidirectional energy storage module when the switch module is turned on, and is restricted by the unidirectional conduction module when the switch module is turned off, and transfers the stored energy to the energy storage module to charge it. The input current and input voltage can be made close to the same phase, thereby improving the power factor and reducing harmonics. The structure of the LED driving circuit is simple, which not only reduces the cost but also improves the reliability of the driving circuit.

[0053] The LED driving circuit and display device provided in this application are respectively introduced in detail below.

[0054] First, an embodiment of the present application provides an LED driving circuit, which can drive a display board and a backlight LED light strip to work. The LED driving circuit can be set on a power board or a display board or a display device integrating the power board. The display board can be a separate power board, or a three-in-one board integrating a display module, a backlight module and a power module, or a two-in-one board integrating any two modules of the display module, the backlight module and the power module; the display device can be a television, a pure display display device, a large display screen and other electronic devices.

[0055] See also Figure 2 , Figure 2 1 is a schematic diagram of a module of an LED driving circuit provided in an embodiment of the present application. The LED driving circuit can be used to drive a display board 210 and a backlight LED light bar 220. The LED driving circuit may include a rectifier module 110, a flyback converter 120, a unidirectional energy storage module 130, a switch module 140, an energy storage module 150, a unidirectional conduction module 160, a first driving module 170 and a second driving module 180, wherein:

[0056] The rectifier module 110 can be used to receive an AC voltage signal and is configured with an output terminal for outputting a rectified voltage signal.

[0057] The flyback converter 120 may have a primary coil Np and a first secondary coil Nm and a second secondary coil Nn respectively coupled to the primary coil Np, the primary coil Np being configured with a tap A, the tap A dividing the primary coil Np into a first coil N1 and a second coil N2, the first secondary coil Nm being configured with an output terminal for outputting a first voltage signal, and the second secondary coil Nn being configured with an output terminal for outputting a second voltage signal.

[0058] One end of the unidirectional energy storage module 130 can be connected to the output terminal of the rectifier module 110 , and the other end can be connected to the tap A.

[0059] The first end of the switch module 140 can be connected to a terminal in the second coil N2 that is different from the tap A, the second end of the switch module 140 is connected to the ground terminal GND, and the third end of the switch module 140 can be used to access a control signal, and the switch module 140 can be controlled to be turned on or off by the control signal.

[0060] A first end of the energy storage module 150 may be connected to a terminal of the first coil N1 that is different from the tap A, and a second end of the energy storage module 150 is connected to the ground terminal GND. The energy storage module 150 may use an electrolytic capacitor.

[0061] One end of the unidirectional conduction module 160 may be connected to the output terminal of the rectifying module 110 , and the other end may be connected to the first end of the energy storage module 150 .

[0062] The first driving module 170 may be connected to the output terminal of the first secondary coil Nm, and is used to drive the backlight LED light bar 220 to operate based on the first voltage signal.

[0063] The second driving module 180 may be connected to the output terminal of the second secondary coil Nn, and is used to drive the display board 210 to operate based on the second voltage signal.

[0064] In the embodiment of the present application, the rectifier module 110 can be any existing rectifier, such as a bridge rectifier, a rectifier bridge, etc. The rectifier module 110 can be connected to an AC voltage signal, rectify the AC voltage signal, and obtain a rectified voltage signal to be output from the output terminal.

[0065] The primary coil Np on the primary side of the flyback converter 120 can be divided into a first coil N1 and a second coil N2 by a tap A, that is, the primary coil Np = the first coil N1 + the second coil N2, and the secondary side of the flyback converter 120 can include a first secondary coil Nm and a second secondary coil Nn, the first secondary coil Nm can be connected to a first output diode D102 and a first output electrolytic capacitor C102, and the second secondary coil Nn can be connected to a second output diode D101 and a second output electrolytic capacitor C101.

[0066] The unidirectional energy storage module 130 can fix the voltage / current flow direction from one end close to the rectifier module 110 to one end close to the tap A of the flyback converter 120, and the unidirectional energy storage module 130 can also store energy when voltage / current flows through it.

[0067] In the embodiment of the present application, the switch module 140 can be turned on or off in response to the control signal. When the switch module 140 is turned on, Figure 3 According to the red arrow flow direction shown in FIG. 1 , the rectifier module 110, the unidirectional energy storage module 130, the second coil N2 and the switch module 140 can form a loop. At this time, the rectified voltage signal output by the output terminal of the rectifier module 110 can store energy in the unidirectional energy storage module 130 when passing through the unidirectional energy storage module 130. Figure 3 The energy storage module 150, the primary coil Np and the switch module 140 can form a discharge loop as shown by the blue arrow. At this time, the two output diodes on the secondary side are reverse biased, that is, the first output diode D102 and the second output diode D101 are cut off, and the first output electrolytic capacitor C102 provides energy for the backlight LED light bar 220, and the second output electrolytic capacitor C101 provides energy for the display board 210.

[0068] When the switch module 140 is disconnected, Figure 4The green arrows in the figure show the flow direction. The unidirectional energy storage module 130, the first coil N1, the energy storage module 150 and the rectifier module 110 form a loop. The unidirectional energy storage module 130 releases the stored energy to charge the energy storage module 150. At this time, the winding of the flyback converter 120 transmits energy to the secondary side. The first output diode D102 and the second output diode D101 are forward-biased, charging the first output electrolytic capacitor C102 and the second output electrolytic capacitor C101 while providing energy to the load, i.e., the backlight LED light bar 220 and the display board 210.

[0069] When the power is turned on for the first time, since the energy storage module 150 has no charge, it is charged through the unidirectional conduction module 160. Since the input AC voltage signal is a sine wave, the unidirectional conduction module 160 is cut off when it is charged to the maximum value; when the voltage of the energy storage module 150 reaches the flyback working condition, the flyback part starts to work; at this time, when the switch module 140 is turned on again, one branch is the unidirectional energy storage module 130-second coil N2-switch module 140 path for energy storage; the other branch is the energy storage module 150 through the first coil N1-first coil N2-second coil N3-second coil N4-second coil N5-second coil N6-second coil N7-second coil N8-second coil N9-second coil N10-second coil N11-second coil N12-second coil N13-second coil N14-second coil N15-second coil N16-second coil N1 The second coil N2-switch module 140 path releases energy, and the current on the switch module 140 is the sum of the currents of the two branches. When the switch module 140 is disconnected, the transformer winding releases energy to the secondary. At the same time, the unidirectional energy storage module 130 charges the energy storage module 150 through the first coil N1. In this process, the unidirectional energy storage module 130 is in a high-frequency charging and discharging mode, and its charging and discharging amplitude is positively correlated with the input voltage amplitude. Therefore, the current of the unidirectional energy storage module 130 basically follows the change of voltage, realizing a function similar to PFC.

[0070] In the embodiment of the present application, the unidirectional energy storage module 130 connected between the output terminal of the rectifier module 110 and the tap A of the primary coil Np stores energy when the switch module 140 is turned on, and when the switch module 140 is turned off, it is limited by the unidirectional conduction module 160 connected between the output terminal of the rectifier module 110 and the energy storage module 150, and the stored energy is transferred to the energy storage module 150 to charge it, so that the input current and the input voltage are close to the same phase, thereby improving the power factor and reducing harmonics. Compared with the related art of reducing harmonics by adding a PFC circuit, the circuit structure is simplified, the cost is reduced, and the reliability of the drive circuit is improved.

[0071] Next, continue to Figure 2 Each unit module shown and the specific implementation methods that may be used in practical applications are explained in detail.

[0072] In some embodiments of the present application, the unidirectional energy storage module 130 may include an energy storage diode Dics and a first inductor L1, the anode of the energy storage diode Dics is connected to the output terminal of the rectifier module 110, the cathode of the energy storage diode Dics is connected to one end of the first inductor L1, and the other end of the first inductor L1 is connected to the tap A.

[0073] like Figure 5 As shown, in the embodiment of the present application, the energy storage module 150 uses the first electrolytic capacitor C1, the switch module 140 uses the first MOS transistor Q1, and a sensing resistor Rsens is connected between the cathode of the first electrolytic capacitor C1 and the source of the first MOS transistor Q1.

[0074] When the first MOS transistor Q1 is turned on in response to the control signal, the rectifier module 110, the energy storage diode Dics, the first inductor L1, the second coil N2, the first MOS transistor Q1 and the sensing resistor Rsens form a loop, and the first inductor L1 is stored with energy through the rectified voltage signal Vin+. The current of the first inductor L1 rises linearly, and the calculation formula is:

[0075]

[0076] At the same time, the first electrolytic capacitor C1, the primary coil Np, the first MOS transistor Q1 and the sensing resistor Rsens form a discharge loop. At this time, the two output diodes on the secondary side are reverse biased, that is, the first output diode D102 and the second output diode D101 are cut off, and the first output electrolytic capacitor C102 provides energy for the backlight LED light bar 220, and the second output electrolytic capacitor C101 provides energy for the display board 210.

[0077] In some embodiments of the present application, the unidirectional conduction module 160 may include a bypass diode Dbyp, an anode of the bypass diode Dbyp is connected to the output terminal of the rectifier module 110 , and a cathode of the bypass diode Dbyp is connected to the first end of the energy storage module 150 .

[0078] Please continue reading Figure 5In the embodiment of the present application, the bypass diode Dbyp is connected across the output terminal of the rectifier module 110 and the positive electrode of the first electrolytic capacitor C1. Therefore, when the first MOS tube Q1 is disconnected in response to the control signal, due to the unidirectional conduction principle of the bypass diode Dbyp, the energy storage diode Dics, the first inductor L1, the first coil N1, the first electrolytic capacitor C1 and the rectifier module 110 form a loop, and the first inductor L1 discharges to charge the first electrolytic capacitor C1. At this time, the flyback converter 120 winding transmits energy to the secondary side, and the first output diode D102 and the second output diode D101 are forward-biased, charging the first output electrolytic capacitor C102 and the second output electrolytic capacitor C101 while providing energy to the load, namely the backlight LED light bar 220 and the display board 210.

[0079] like Figure 6 As shown, in some embodiments of the present application, the first driving module 170 may include a buck conversion control unit, a first controllable switch Q801, a first unidirectional diode D801, a first energy storage inductor L801 and a first energy storage capacitor C801.

[0080] The first end of the first controllable switch Q801 is connected to the step-down conversion control unit to access the first control signal Vgate, the second end of the first controllable switch Q801 is respectively connected to the anode of the first unidirectional diode D801 and the first end of the first energy storage inductor L801, the third end of the first controllable switch Q801 is grounded, the cathode of the first unidirectional diode D801 is respectively connected to the output terminal of the first secondary coil Nm and the positive electrode of the first energy storage capacitor C801, the second end of the first energy storage inductor L801 is connected to the negative electrode of the first energy storage capacitor C801, and the backlight LED light strip is connected in parallel with the first energy storage capacitor C801.

[0081] In the embodiment of the present application, the first driving module 170 may be a BUCK step-down conversion circuit, and the step-down conversion control unit may output a first control signal Vgate to control the on or off of the first controllable switch Q801.

[0082] When the first controllable switch Q801 is turned on in response to the first control signal Vgate, the first voltage signal +VBL provided by the first secondary coil Nm flows to the ground through the first energy storage capacitor C801, the first energy storage inductor L801 and the first controllable switch Q801. At this time, the first unidirectional diode D801 is reverse biased and cut off, and the first voltage signal +VBL charges the first energy storage capacitor C801, the first energy storage inductor L801 and supplies power to the backlight LED strip, driving the backlight LED strip to emit light.

[0083] When the first controllable switch Q801 is disconnected in response to the first control signal Vgate, the first unidirectional diode D801 is forward biased and turned on, and the first energy storage capacitor C801 and the first energy storage inductor L801 discharge to supply energy to the backlight LED light bar, driving the backlight LED light bar to emit light.

[0084] Please continue reading Figure 6 In some embodiments of the present application, the buck conversion control unit can also be connected to the first preset port of the display board to access the first switch control signal; the buck conversion control unit can be used to generate a first control signal Vgate according to the accessed first switch control signal to control the first controllable switch Q801 to be turned on or off.

[0085] In the embodiment of the present application, the first preset port of the display board can be any one or more input / output (IO) ports on the board. The display board can output a first switch control signal to the buck conversion control unit through the first preset port, so that the buck conversion control unit can generate a first control signal Vgate in response to the first switch control signal, thereby controlling the first controllable switch Q801 to be turned on or off through the first control signal Vgate.

[0086] It can be understood that in some embodiments, the display board can also generate a modulation signal to the control circuit, so that the control circuit can generate a control signal according to the modulation signal and output it to the gate of the first MOS tube Q1 to control the conduction or disconnection of the first MOS tube Q1.

[0087] like Figure 7 As shown, in some embodiments of the present application, the first driving module 170 may include a boost conversion control unit, a second controllable switch Q802, a second unidirectional diode D802, a second energy storage inductor L802 and a second energy storage capacitor C802.

[0088] The first end of the second controllable switch Q802 is connected to the boost conversion control unit to access the second control signal Vgate2, the second end of the second controllable switch Q802 is respectively connected to the second end of the second energy storage inductor L802 and the anode of the second unidirectional diode D802, the third end of the second controllable switch Q802 is grounded, the first end of the second energy storage inductor L802 is connected to the output terminal of the first secondary coil Nm, the cathode of the second unidirectional diode D802 is connected to the positive electrode of the second energy storage capacitor C802, the negative electrode of the second energy storage capacitor C802 is grounded, and the backlight LED light strip is connected in parallel with the second energy storage capacitor C802.

[0089] In the embodiment of the present application, the first driving module 170 may be a BOOST boost conversion circuit, and the boost conversion control unit may output a second control signal Vgate2 to control the on or off of the second controllable switch Q802.

[0090] When the second controllable switch Q802 is turned on in response to the second control signal Vgate2, the first voltage signal +VBL provided by the first secondary coil Nm flows to the ground through the second energy storage inductor L802. At this time, the second unidirectional diode D802 is reverse biased and cut off, and the first voltage signal +VBL charges the second energy storage inductor L802, and the second energy storage capacitor C802 discharges, driving the backlight LED strip to emit light.

[0091] When the second controllable switch Q802 is disconnected in response to the second control signal Vgate2, the second unidirectional diode D802 is forward biased and turned on, and the first voltage signal +VBL and the second energy storage inductor L802 charge the second energy storage capacitor C802 and supply energy to the backlight LED strip, driving the backlight LED strip to emit light.

[0092] Please continue reading Figure 7 In some embodiments of the present application, the boost conversion control unit can also be connected to a second preset port of the display board to access a second switch control signal; the boost conversion control unit can be used to generate a second control signal Vgate2 according to the accessed second switch control signal to control the second controllable switch Q802 to be turned on or off.

[0093] In the embodiment of the present application, the second preset port of the display board can also be any one or more IO ports on the board. The display board can output the second switch control signal to the boost conversion control unit through the second preset port, so that the boost conversion control unit can generate a second control signal Vgate2 in response to the second switch control signal, thereby controlling the second controllable switch Q802 to be turned on or off through the second control signal Vgate2.

[0094] Similarly, in some embodiments, the display board can also generate a modulation signal to the control circuit, so that the control circuit can generate a control signal according to the modulation signal and output it to the gate of the first MOS tube Q1 to control the conduction or disconnection of the first MOS tube Q1.

[0095] In the embodiment of the present application, the backlight LED light strip is driven by a BOOST step-up conversion circuit, which can adapt to backlight LED light strips with different voltage and current specifications and has a wider range of applications.

[0096] See also Figure 8In some embodiments of the present application, the first driving module 170 may include a sampling resistor Rb1, a first operational amplifier U101A, a third unidirectional diode D104 and a photocoupler; wherein the sampling resistor Rb1 is connected in series with the backlight LED light bar and is connected to the input end of the first operational amplifier U101A, the output end of the first operational amplifier U101A is connected to the cathode of the third unidirectional diode D104, the anode of the third unidirectional diode D104 is connected to the cathode of the light emitter PC101A of the photocoupler, the anode of the light emitter PC101A of the photocoupler is connected to the driving voltage signal 12V, and the light receiver PC101B of the photocoupler is connected to the switch module, i.e., the gate of the first MOS tube Q1, through the control circuit.

[0097] In the embodiment of the present application, the current of the backlight LED light strip is sampled through the sampling resistor Rb1. When the current increases, the voltage difference across the sampling resistor Rb1 increases, thereby increasing the input voltage of the first operational amplifier U101A, which weakens the light emission of the light emitter PC101A of the optocoupler, thereby weakening the conduction degree of the light receiver PC101B of the optocoupler. The control circuit controls the duty cycle of the first MOS tube Q1 to decrease according to the conduction degree of the light receiver PC101B, thereby adjusting the first voltage signal output by the first secondary coil Nm to decrease, thereby reducing the voltage and current of the backlight LED light strip.

[0098] On the contrary, if the current of the backlight LED light strip decreases, the voltage difference across the sampling resistor Rb1 becomes smaller, thereby reducing the input voltage of the first operational amplifier U101A, which increases the luminescence of the light emitter PC101A of the optocoupler, thereby increasing the conduction degree of the light receiver PC101B of the optocoupler, and the control circuit controls the duty cycle of the first MOS tube Q1 to increase according to the conduction degree of the light receiver PC101B, thereby increasing the first voltage signal output by the first secondary coil Nm, thereby increasing the voltage and current of the backlight LED light strip.

[0099] Please continue reading Figure 8 In some embodiments of the present application, the second driving module 180 may include a third controllable switch Q101, a third energy storage inductor L101, a third energy storage capacitor C103, a fourth unidirectional diode D103 and a feedback control unit.

[0100] The first end of the third controllable switch Q101 is connected to the output end of the feedback control unit to access the feedback control signal, the second end of the third controllable switch Q101 is connected to the output terminal of the second secondary coil Nn, the third end of the third controllable switch Q101 is respectively connected to the first end of the third energy storage inductor L101 and the cathode of the fourth unidirectional diode D103, and the second end of the third energy storage inductor L101 is respectively connected to the positive electrode of the third energy storage capacitor C103, the input end of the feedback control unit, the anode of the light emitter PC101A of the photoelectric coupler and the third preset port of the display board.

[0101] In the embodiment of the present application, the second voltage signal output by the second secondary coil Nn changes the voltage range according to the change of the backlight LED light bar voltage. The specific voltage range can be set according to the backlight LED light bar voltage and the turns ratio of the two windings of the flyback converter 120.

[0102] In an embodiment of the present application, the third preset port of the display board can be a power access terminal. The feedback control unit detects the voltage signal provided to the display board and the power amplifier circuit. The feedback control unit generates a feedback control signal according to the detected voltage signal to adjust the duty cycle of the third controllable switch Q101, thereby ensuring a stable output of 12V voltage to the display board and the power amplifier circuit.

[0103] Specifically, when the third controllable switch Q101 is turned on, the second voltage signal output by the second secondary coil Nn charges the third energy storage inductor L101 and the third energy storage capacitor C103 and supplies power to the display board and the power amplifier circuit. At this time, the fourth unidirectional diode D103 is reverse biased and cut off; when the third controllable switch Q101 is disconnected, the fourth unidirectional diode D103 is turned on, and the third energy storage inductor L101 and the third energy storage capacitor C103 stably output a 12V voltage to provide to the display board and the power amplifier circuit.

[0104] like Figure 8 As shown, if the backlight LED strip is not connected during the debugging stage, the second voltage signal output by the second secondary coil Nn can also be detected by the second operational amplifier U101B in the embodiment of the present application. The conduction degree of the photocoupler can also be adjusted according to the feedback of the second operational amplifier U101B, thereby adjusting the duty cycle of the first MOS tube Q1 to adjust the output voltage on the secondary side.

[0105] Based on the LED driving circuit in the above embodiment, on the basis of the above embodiment, the embodiment of the present application further provides a display device, which may include a device body and Figures 2 to 8 Corresponding to the LED driving circuit in any embodiment.

[0106] The display device may be a television, a pure display device, a large display screen or other electronic device.

[0107] Since the display device includes the present application Figures 2 to 8 Corresponding to the LED driving circuit in any embodiment, therefore, the present application can be implemented as follows Figures 2 to 8 For all the beneficial effects that can be achieved by the LED driving circuit in any embodiment, please refer to the previous description in detail, which will not be repeated here.

[0108] The above are only preferred embodiments of the present application, and are not intended to limit the present application in any form. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present application. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. An LED driving circuit, characterized in that: The LED driving circuit is used to drive the display board and the backlight LED light bar to work, and the LED driving circuit includes: A rectifier module, used for receiving an AC voltage signal and provided with an output terminal for outputting a rectified voltage signal; A flyback converter, comprising a primary coil and a first secondary coil and a second secondary coil respectively coupled to the primary coil, wherein the primary coil is provided with a tap, the tap divides the primary coil into a first coil and a second coil, the first secondary coil is provided with an output terminal for outputting a first voltage signal, and the second secondary coil is provided with an output terminal for outputting a second voltage signal; A unidirectional energy storage module, one end of which is connected to the output terminal of the rectifier module, and the other end of which is connected to the tap; a switch module, wherein a first end of the switch module is connected to a terminal of the second coil that is different from the tap, a second end of the switch module is connected to a ground terminal, and a third end of the switch module is used to access a control signal, and the switch module is turned on or off by the control signal; An energy storage module, wherein a first end of the energy storage module is connected to a terminal of the first coil that is different from the tap, and a second end of the energy storage module is connected to the ground terminal; A unidirectional conduction module, one end of which is connected to the output terminal of the rectifier module, and the other end of which is connected to the first end of the energy storage module; A first driving module, connected to the output terminal of the first secondary coil, and used for driving the backlight LED light bar to work based on the first voltage signal; The second driving module is connected to the output terminal of the second secondary coil and is used to drive the display board to operate based on the second voltage signal.

2. The LED driving circuit according to claim 1, characterized in that: The unidirectional energy storage module includes an energy storage diode and a first inductor, the anode of the energy storage diode is connected to the output terminal of the rectifier module, the cathode of the energy storage diode is connected to one end of the first inductor, and the other end of the first inductor is connected to the tap.

3. The LED driving circuit according to claim 1, characterized in that: The unidirectional conducting module comprises a bypass diode, an anode of the bypass diode is connected to the output terminal of the rectifying module, and a cathode of the bypass diode is connected to the first end of the energy storage module.

4. The LED driving circuit according to claim 1, characterized in that: The first driving module includes a buck conversion control unit, a first controllable switch, a first unidirectional diode, a first energy storage inductor and a first energy storage capacitor; The first end of the first controllable switch is connected to the step-down conversion control unit to access the first control signal, the second end of the first controllable switch is respectively connected to the anode of the first unidirectional diode and the first end of the first energy storage inductor, the third end of the first controllable switch is grounded, the cathode of the first unidirectional diode is respectively connected to the output terminal of the first secondary coil and the positive electrode of the first energy storage capacitor, the second end of the first energy storage inductor is connected to the negative electrode of the first energy storage capacitor, and the backlight LED light strip is connected in parallel with the first energy storage capacitor.

5. The LED driving circuit according to claim 4, characterized in that: The step-down conversion control unit is also connected to the first preset port of the display board to receive the first switch control signal; The buck conversion control unit is used to generate the first control signal according to the first switch control signal connected to control the first controllable switch to be turned on or off.

6. The LED driving circuit according to claim 1, characterized in that: The first driving module includes a boost conversion control unit, a second controllable switch, a second unidirectional diode, a second energy storage inductor and a second energy storage capacitor; The first end of the second controllable switch is connected to the boost conversion control unit to access the second control signal, the second end of the second controllable switch is respectively connected to the second end of the second energy storage inductor and the anode of the second unidirectional diode, the third end of the second controllable switch is grounded, the first end of the second energy storage inductor is connected to the output terminal of the first secondary coil, the cathode of the second unidirectional diode is connected to the positive electrode of the second energy storage capacitor, the negative electrode of the second energy storage capacitor is grounded, and the backlight LED light strip is connected in parallel with the second energy storage capacitor.

7. The LED driving circuit according to claim 6, characterized in that: The boost conversion control unit is also connected to a second preset port of the display board to receive a second switch control signal; The boost conversion control unit is used to generate the second control signal according to the second switch control signal connected to control the second controllable switch to be turned on or off.

8. The LED driving circuit according to claim 1, characterized in that: The first driving module includes a sampling resistor, a first operational amplifier, a third unidirectional diode and a photocoupler; The sampling resistor is connected in series with the backlight LED light strip and is connected to the input end of the first operational amplifier. The output end of the first operational amplifier is connected to the cathode of the third unidirectional diode. The anode of the third unidirectional diode is connected to the cathode of the light emitter of the photoelectric coupler. The anode of the light emitter of the photoelectric coupler is connected to the driving voltage signal. The light receiver of the photoelectric coupler is connected to the third end of the switch module through the control circuit.

9. The LED driving circuit according to claim 8, characterized in that: The second driving module includes a third controllable switch, a third energy storage inductor, a third energy storage capacitor, a fourth unidirectional diode and a feedback control unit; The first end of the third controllable switch is connected to the output end of the feedback control unit to access the feedback control signal, the second end of the third controllable switch is connected to the output terminal of the second secondary coil, the third end of the third controllable switch is respectively connected to the first end of the third energy storage inductor and the cathode of the fourth unidirectional diode, and the second end of the third energy storage inductor is respectively connected to the positive electrode of the third energy storage capacitor, the input end of the feedback control unit, the anode of the light emitter of the photoelectric coupler and the third preset port of the display board.

10. A display device, characterized in that: The device comprises a device body and an LED driving circuit as described in any one of claims 1 to 9.

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