Power supply circuit, control method and display device

Abstract

The present invention discloses a power supply circuit, a control method and a display device, wherein the power supply circuit comprises a power supply circuit, a first drive circuit, a sampling circuit and a control chip; the input end of the power supply circuit is used to connect to a mains circuit, and the output end of the power supply circuit is used to connect to a backlight LED module and an audio and video module; the first end of the sampling circuit is connected to the power supply circuit for obtaining a sampling voltage; the control chip is connected to the sampling circuit and the first drive circuit for generating a driving control signal when the sampling voltage meets a voltage drop evaluation condition, and outputting the driving control signal to the first drive circuit. The power supply circuit can reduce the power of the backlight LED module when the mains voltage drops so that the total input current remains stable, so that the total current of the power supply circuit will not increase due to the mains undervoltage, stabilize the current in the power supply circuit, protect the reliability of the power supply circuit, and alleviate the overload condition of the power grid at the same time.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a power supply circuit, a control method and a display device. Background Art

[0002] Grid voltage drop is an important problem in the operation of power systems. The main reasons include power failure, load fluctuation and long lines. Grid voltage drop has a particularly prominent impact on display devices such as monitors, TVs, conference machines, TVs, monitors, etc. When the power supply voltage is lower than 220V, in order to ensure normal operation, the total current output by the power supply circuit in the display device will increase, and the corresponding power supply part, especially the electronic components of the AC-DC converter part, will increase in temperature, resulting in reduced device reliability, damage, and cessation of operation. Summary of the invention

[0003] The embodiments of the present invention provide a power supply circuit, a control method and a display device to solve the problem that the reliability of display device components is reduced or even damaged due to a reduction in grid voltage.

[0004] An embodiment of the present invention provides a power supply circuit, including a power supply circuit, a first drive circuit, a sampling circuit and a control chip;

[0005] The input end of the power supply circuit is used to connect to the mains circuit, and the output end of the power supply circuit is used to connect to the backlight LED module and the audio and video module;

[0006] The first end of the sampling circuit is connected to the power supply circuit for obtaining a sampling voltage;

[0007] The control chip is connected to the sampling circuit and the first driving circuit, and is used to generate a first control voltage according to the sampling voltage when the sampling voltage meets the voltage drop evaluation condition, and output a driving control signal to the first driving circuit based on the first control voltage;

[0008] The first driving circuit is connected to the power supply circuit and is used to adjust the power input to the backlight LED module based on the driving control signal so that the total current output by the power supply circuit does not exceed the rated current.

[0009] Preferably, the power supply circuit further includes an ambient light detection module;

[0010] The ambient light detection module is connected to the control chip and is used to output a second control voltage to the control chip according to the detected ambient light intensity;

[0011] The control chip is used to generate a drive control signal according to the second control voltage when the first control voltage is greater than or equal to the second control voltage; and to generate a drive control signal according to the first control voltage when the first control voltage is less than the second control voltage.

[0012] Preferably, the power supply circuit includes a rectifier module, a first DC-DC conversion module and a second DC-DC conversion module;

[0013] The input end of the rectifier module is used to connect to the mains circuit;

[0014] The first DC-DC conversion module and the second DC-DC conversion module are connected in parallel to the output end of the rectifier module;

[0015] The first DC-DC conversion module is connected to the output end of the rectifier module and the backlight LED module;

[0016] The second DC-DC conversion module is connected to the output end of the rectifier module and the audio and video module;

[0017] The first drive circuit is connected to the first DC-DC conversion module, and is used to adjust the output power of the first DC-DC conversion module based on the drive control signal so that the total current output by the rectifier module does not exceed the rated current.

[0018] Preferably, the first driving circuit comprises a driving chip;

[0019] The control end of the driving chip is connected to the control chip, and the driving end of the driving chip is connected to the first DC-DC conversion module, and is used to adjust the output power of the first DC-DC conversion module based on the driving control signal.

[0020] Preferably, the sampling circuit includes a voltage dividing module and an isolation module;

[0021] The voltage dividing module is connected to the output end of the rectifier module and is used to obtain a sampled voltage;

[0022] The first end of the isolation module is connected to the voltage dividing module, and the second end of the isolation module is connected to the control chip, and is used to output the sampling voltage to the control chip.

[0023] Preferably, the power supply circuit further includes an EMI module and a PFC module;

[0024] The first end of the EMI module is used to connect to the mains circuit, and the second end of the EMI module is connected to the rectifier module;

[0025] A first end of the PFC module is connected to the rectifier module, and a second end of the PFC module is connected to the first DC-DC conversion module and the second DC-DC conversion module.

[0026] An embodiment of the present invention further provides a control method for a power supply circuit, which is applicable to any of the power supply circuits described above, and the control method includes:

[0027] Get the sample voltage;

[0028] When the sampled voltage is less than a preset voltage threshold, it is determined that a voltage drop evaluation condition is met, and a first control voltage is determined according to the sampled voltage;

[0029] Based on the first control voltage, a driving control signal is generated, and the driving control signal is output to the first driving circuit, so that the first driving circuit adjusts the power input to the backlight LED module according to the driving control signal so that the total current output by the power supply circuit does not exceed the rated current.

[0030] Preferably, determining the first control voltage according to the sampled voltage includes:

[0031] based on , obtaining the first control voltage;

[0032] Among them, U3' is the first control voltage; Po is the output power of the audio and video module under the standard output voltage of the AC circuit; Pb is the output power of the backlight LED module under the standard output voltage of the AC circuit; U2 is the sampling voltage; U1 is the output voltage of the rectifier module under the standard output voltage of the AC circuit; K is the voltage divider constant.

[0033] Preferably, generating a driving control signal based on the first control voltage includes:

[0034] Acquire a second control voltage output by the ambient light detection module;

[0035] If the first control voltage is greater than or equal to the second control voltage, generating a driving control signal based on the second control voltage;

[0036] If the first control voltage is less than the second control voltage, a driving control signal is generated based on the first control voltage.

[0037] An embodiment of the present invention further provides a display device, comprising a backlight LED module, an audio and video module, and any one of the power supply circuits described above, wherein the control chip can run the control method of the power supply circuit described above;

[0038] The audio and video module and the backlight LED module are connected to the power supply circuit.

[0039] The power supply circuit, control method and display device provided by the embodiments of the present invention can adjust the power of the backlight LED module according to the output voltage provided by the AC power circuit. When the output voltage provided by the AC power circuit decreases, the total current input to the backlight LED module and the audio and video module can be kept stable by reducing the power of the backlight LED module, so that the total current of the power supply circuit will not increase due to undervoltage of the AC power circuit, the current in the power supply circuit is stabilized, the reliability design of the power supply product is met, the power supply product can be operated within the design specifications, and the probability of product damage is reduced. At the same time, reducing the power of the backlight LED module can also alleviate the overload condition of the power grid, so that the output voltage provided by the AC power circuit approaches the normal value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0041] Figure 1 is a schematic diagram of a block diagram of a power supply circuit in one embodiment of the present invention;

[0042] Figure 2 is another block diagram of a power supply circuit in one embodiment of the present invention;

[0043] Figure 3 is a flow chart of a control method of a power supply circuit in one embodiment of the present invention;

[0044] Figure 4 is another flow chart of a method for controlling a power supply circuit in one embodiment of the present invention.

[0045] In the figure: 1. power supply circuit; 11. rectifier module; 12. first DC-DC conversion module; 13. second DC-DC conversion module; 14. EMI module; 15. PFC module; 2. first drive circuit; 3. sampling circuit; 31. voltage divider module; 32. isolation module; 4. control chip; 5. backlight LED module; 6. audio and video module; 7. ambient light detection module. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0048] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0049] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0050] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0051] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0052] An embodiment of the present invention provides a power supply circuit, including a power supply circuit 1, a first drive circuit 2, a sampling circuit 3 and a control chip 4; the input end of the power supply circuit 1 is used to connect to the mains circuit, and the output end of the power supply circuit 1 is used to connect to the backlight LED module 5 and the audio and video module 6; the first end of the sampling circuit 3 is connected to the power supply circuit 1 for obtaining a sampling voltage; the control chip 4 is connected to the sampling circuit 3 and the first drive circuit 2, and is used to generate a first control voltage according to the sampling voltage when the sampling voltage meets the voltage drop evaluation condition, and output a drive control signal to the first drive circuit 2 based on the first control voltage; the first drive circuit 2 is connected to the power supply circuit 1, and is used to adjust the power input to the backlight LED module 5 based on the drive control signal, so that the total current output by the power supply circuit 1 does not exceed the rated current.

[0053] As an example, the power supply circuit includes a power supply circuit 1, a first drive circuit 2, a sampling circuit 3 and a control chip 4. The input end of the power supply circuit 1 is used to connect to the mains circuit, and the output end of the power supply circuit 1 is used to connect to the backlight LED module 5 and the audio and video module 6, and is used to take power from the mains circuit to supply power to the backlight LED module 5 and the audio and video module 6. The first end of the sampling circuit 3 is connected to the power supply circuit 1, and is used to obtain the sampling voltage; the control chip 4 is connected to the sampling circuit 3 and the first drive circuit 2, and is used to control the first drive circuit 2 to drive normally according to the preset driving mode when the sampling voltage does not meet the voltage drop evaluation condition, for example, when the sampling voltage is not less than the preset voltage threshold, so that the backlight LED module 5 maintains the current working state; it is also used to judge that the output voltage provided by the current mains circuit has dropped due to a large grid load, etc., when the sampling voltage meets the voltage drop evaluation condition, for example, when the sampling voltage is less than the preset voltage threshold, and then obtain the first control voltage based on the sampling voltage, generate a drive control signal based on the first control voltage, and output the drive control signal to the first drive circuit 2. The first driving circuit 2 is connected to the power supply circuit 1 and is used to adjust the power input to the backlight LED module 5 based on the driving control signal so that the total current output by the power supply circuit 1 does not exceed the rated current.

[0054] When the output voltage provided by the mains circuit drops due to a large grid load, the sampling voltage obtained by the sampling circuit 3 also drops and decreases to less than the preset voltage threshold. The control chip 4 controls the sampled voltage based on the dropped sampled voltage. , calculate and obtain a new first control voltage, where U3' is the first control voltage, Po is the output power of the audio and video module 6 under the standard output voltage (220V) of the mains circuit; Pb is the output power of the backlight LED module 5 under the standard output voltage of the mains circuit; U2 is the sampling voltage; U1 is the output voltage of the rectifier module 11 under the standard output voltage of the mains circuit; K is the voltage division constant. In the formula, the first control voltage is proportional to the sampling voltage, so the updated first control voltage will also decrease as the sampling voltage decreases. The control chip 4 outputs a drive control signal to the first drive circuit 2 based on the updated first control voltage, so that the first drive circuit 2 reduces the power input to the backlight LED module 5 after receiving the drive control signal, so that the total current output by the power supply circuit 1 does not exceed the rated current, that is, does not exceed the total current output by the power supply circuit 1 under the standard output voltage (220V) of the mains circuit.

[0055] In this example, the power supply circuit can adjust the power of the backlight LED module 5 according to the output voltage provided by the AC power circuit. When the output voltage provided by the AC power circuit drops, the total current input to the backlight LED module 5 and the audio and video module 6 can be kept stable by reducing the power of the backlight LED module 5, so that the total current of the power supply circuit will not increase due to undervoltage of the AC power circuit, thereby stabilizing the current in the power supply circuit 1, meeting the reliability design of the power supply product, enabling it to operate within the design specifications, and reducing the probability of product damage. At the same time, reducing the power of the backlight LED module 5 can also alleviate the overload condition of the power grid, so that the output voltage provided by the AC power circuit approaches the normal value.

[0056] In one embodiment, the power supply circuit also includes an ambient light detection module 7; the ambient light detection module 7 is connected to the control chip 4, and is used to output a second control voltage to the control chip 4 according to the detected ambient light intensity; the control chip 4 is used to generate a drive control signal according to the second control voltage when the first control voltage is greater than or equal to the second control voltage; and to generate a drive control signal according to the first control voltage when the first control voltage is less than the second control voltage.

[0057] As an example, the power supply circuit also includes an ambient light detection module 7. The ambient light detection module 7 is connected to the control chip 4, and is used to output a second control voltage to the control chip 4 according to the detected ambient light intensity. The second control voltage is proportional to the ambient light intensity, and can increase with the increase of the ambient light intensity, and the maximum value does not exceed the first preset voltage value (for example, 3V), and the minimum value does not fall below the second preset voltage value (for example, 1.5V). The control chip 4 is used to generate a drive control signal according to the second control voltage when the first control voltage is greater than or equal to the second control voltage, and to generate a drive control signal according to the first control voltage when the first control voltage is less than the second control voltage.

[0058] When the first control voltage is greater than or equal to the second control voltage, it can be determined that the ambient light intensity can allow the backlight LED module 5 to operate at a lower output power. At the same time, since the first control voltage is greater than or equal to the second control voltage, the power of the backlight LED module 5 adjusted according to the second control voltage can also adapt to the supply capacity of the AC power circuit, and the total current output by the power supply circuit 1 will not exceed the rated current. Therefore, brightness matching can be given priority, and a lower second control voltage can be used to generate a drive control signal so that the first drive circuit 2 controls the backlight LED module 5 to operate at a lower output power according to the drive control signal to match the current ambient light intensity, thereby preventing the backlight LED module 5 from being too high in power, causing glare or waste of electricity, and other adverse conditions.

[0059] When the first control voltage is less than the second control voltage, it can be determined that the output voltage of the AC power circuit has dropped and is less than 220V. To prevent overcurrent and ensure that the total current output by the power supply circuit 1 does not exceed the rated current, a drive control signal should be generated based on the first control voltage to appropriately reduce the brightness of the backlight LED module 5 to adapt to special circumstances and ensure the normal operation of the equipment.

[0060] In one embodiment, if Figure 1 As shown, the power supply circuit 1 includes a rectifier module 11, a first DC-DC conversion module 12 and a second DC-DC conversion module 13; the input end of the rectifier module 11 is used to connect to the AC power circuit; the first DC-DC conversion module 12 and the second DC-DC conversion module 13 are connected in parallel to the output end of the rectifier module 11; the first DC-DC conversion module 12 is used to connect to the backlight LED module 5, and the second DC-DC conversion module 13 is used to connect to the audio and video module 6; the first drive circuit 2 is connected to the first DC-DC conversion module 12, and is used to adjust the output power of the first DC-DC conversion module 12 based on the drive control signal, so that the total current output by the rectifier module 11 does not exceed the rated current.

[0061] As an example, the power supply circuit 1 includes a rectifier module 11, a first DC-DC conversion module 12, and a second DC-DC conversion module 13. The input end of the rectifier module 11 is used to connect to the mains circuit, and is used to convert the alternating current output by the mains circuit into direct current. The first DC-DC conversion module 12 and the second DC-DC conversion module 13 are connected in parallel to the output end of the rectifier module 11, the first DC-DC conversion module 12 is used to connect to the backlight LED module 5, and supply power to the backlight LED module 5, and the second DC-DC conversion module 13 is used to connect to the audio and video module 6, and supply power to the audio and video module 6. The first drive circuit 2 is connected to the first DC-DC conversion module 12, and is used to adjust the output power of the first DC-DC conversion module 12 based on the drive control signal, so that the total current output by the rectifier module 11 does not exceed the rated current.

[0062] As another example, Figure 2 As shown, the second DC-DC conversion module 13 can also be connected to the control chip 4, the control chip 4 is connected to the audio and video module 6, the control chip 4 can be a system-on-chip (SOC), which is used to control the operation of the audio and video module 6, and the second DC-DC conversion module 13 is used to perform DC-DC conversion on the voltage output by the rectifier module 11, converting it into two power supply voltages of 5V / 12V and 18 / 24V to power the control chip 4 and the audio and video module 6.

[0063] In one embodiment, the first driving circuit 2 includes a driving chip; the control end of the driving chip is connected to the control chip 4, and the driving end of the driving chip is connected to the first DC-DC conversion module 12, which is used to adjust the output power of the first DC-DC conversion module 12 based on the driving control signal.

[0064] As an example, the first driving circuit 2 includes a driving chip. The control end of the driving chip is connected to the control chip 4, and the driving end of the driving chip is connected to the first DC-DC conversion module 12, and is used to adjust the output power of the first DC-DC conversion module 12 based on the driving control signal. Specifically, the driving control signal can be a PWM signal generated according to the first control voltage or the second control voltage, and the driving chip adjusts the output power of the first DC-DC conversion module 12 according to the amplitude of the PWM signal.

[0065] When the output voltage provided by the AC power circuit decreases, the sampling voltage obtained by the sampling circuit 3 also decreases accordingly. The control chip 4 calculates and obtains the first control voltage based on the sampling voltage and also decreases accordingly. The control chip 4 outputs a drive control signal to the first drive circuit 2 based on the decreased first control voltage, that is, the amplitude of the PWM signal also decreases accordingly. The drive chip can control the reduction of the output power of the first DC-DC conversion module 12 according to the PWM signal after the amplitude decreases, so that the total current output by the power supply module does not exceed the rated current.

[0066] In one embodiment, the sampling circuit 3 includes a voltage divider module 31 and an isolation module 32; the voltage divider module 31 is connected to the output end of the rectifier module 11, and is used to obtain the sampling voltage corresponding to the rectifier module 11; the first end of the isolation module 32 is connected to the voltage divider module 31, and the second end of the isolation module 32 is connected to the control chip 4, and is used to output the sampling voltage to the control chip 4.

[0067] As an example, the sampling circuit 3 includes a voltage divider module 31 and an isolation module 32. The voltage divider module 31 is connected to the output end of the rectifier module 11, and may specifically include a first voltage divider resistor R1 and a second voltage divider resistor R2 that are arranged in series between the output end of the rectifier module 11 and the ground, wherein the first end of the first voltage divider resistor R1 is connected to the output end of the rectifier module 11, the second end of the first voltage divider resistor R1 is connected to the first end of the second voltage divider resistor R2, and the second end of the second voltage divider resistor R2 is grounded. The second end of the first voltage divider resistor R1 is connected to the first end of the isolation module 32, and the sampling voltage obtained by the voltage divider module 31 is the same as the voltage across the second voltage divider resistor R2, and the voltage divider constant K of the voltage divider module 31 is The isolation module 32 may include an optical coupling component, a first end of which is connected to the voltage divider module 31 , and a second end of which is connected to the control chip 4 , for isolating the voltage divider module 31 of the front stage and the control chip 4 of the rear stage to prevent signal interference.

[0068] In one embodiment, the power supply circuit 1 also includes an EMI module 14 and a PFC module 15; the first end of the EMI module 14 is used to connect to the AC power circuit, and the second end of the EMI module 14 is connected to the rectifier module 11; the first end of the PFC module 15 is connected to the rectifier module 11, and the second end of the PFC module 15 is connected to the first DC-DC conversion module 12 and the second DC-DC conversion module 13.

[0069] As an example, the power supply circuit 1 also includes an EMI module 14 and a PFC module 15; the first end of the EMI module 14 is used to connect to the mains circuit, and the second end of the EMI module 14 is connected to the rectifier module 11; the first end of the PFC module 15 is connected to the rectifier module 11, and the second end of the PFC module 15 is connected to the first DC-DC conversion module 12 and the second DC-DC conversion module 13. The EMI module 14 is used to attenuate high-frequency noise, prevent these noise signals from entering the inside of the device or propagating to the external environment, thereby maintaining the purity of the signal inside the device and the electromagnetic compatibility of the external environment. Correct the phase difference between current and voltage, reduce the loss of exchange power, and thus improve the conversion efficiency of the power supply. The PFC module 15 is used to correct the phase difference between current and voltage, reduce the loss of exchange power, and improve the conversion efficiency.

[0070] The embodiment of the present invention further provides a control method for a power supply circuit, which is described by taking the application of the control method in the power supply circuit in the above embodiment as an example. Figure 3 As shown, the following steps are included in the control chip 4:

[0071] S301: Obtaining a sampled voltage;

[0072] S302: When the sampled voltage is less than a preset voltage threshold, it is determined that a voltage drop evaluation condition is met, and a first control voltage is determined according to the sampled voltage;

[0073] S303: Generate a driving control signal based on the first control voltage, and output the driving control signal to the first driving circuit, so that the first driving circuit adjusts the power input to the backlight LED module according to the driving control signal, so that the total current output by the power supply circuit does not exceed the rated current.

[0074] As an example, in step S301, the control chip 4 obtains the sampled voltage in real time according to the preset sampling frequency. The sampled voltage is the voltage obtained after the voltage divider module 31 in the sampling circuit 3 divides the voltage output by the mains circuit, and the voltage divider constant of the voltage divider module 31 is K. The sampled voltage can characterize the magnitude of the current output voltage of the mains circuit. When the output voltage of the mains circuit drops due to reasons such as a large grid load, the sampled voltage will also drop accordingly.

[0075] Among them, the first control voltage is a reference voltage for the control chip 4 to obtain the driving control signal. The control chip 4 can generate a driving control signal (PWM signal) of corresponding amplitude according to the magnitude of the first control voltage, and output it to the driving chip connected to the backlight LED module 5, so that the driving chip adjusts the output power of the first DC-DC conversion module 12 according to the driving control signal. The preset voltage algorithm is pre-set and is used to control the reduction of the power input to the backlight LED module 5 when the output voltage of the current mains circuit is less than 220V, so that the total current output by the power supply circuit 1 does not exceed the rated current, that is, the first control voltage obtained based on the sampling voltage and the preset voltage algorithm can reduce the power input to the backlight LED module 5 after the control chip 4 generates a driving control signal based on the first control voltage to control the driver chip to work, so that the total current output by the power supply circuit 1 does not exceed the rated current.

[0076] As an example, in step S302 and step S303, when the control chip 4 detects that the sampled voltage is less than the preset voltage threshold, it is determined that the voltage drop evaluation condition is met, that is, it is determined that the output voltage provided by the current AC power circuit has dropped due to a large grid load, etc. At this time, the control chip 4 obtains the first control voltage based on the sampled voltage, and obtains the drive control signal based on the first control voltage, so that the first drive circuit 2 controls the reduction of the power input to the backlight LED module 5 after receiving the drive control signal, so that the total current output by the power supply circuit 1 does not exceed the rated current.

[0077] In this example, the control chip 4 can adjust the power of the backlight LED module 5 according to the sampling voltage, and when the output voltage provided by the AC power circuit drops, the control chip 4 can reduce the power of the backlight LED module 5 to keep the total current input to the backlight LED module 5 and the audio and video module 6 stable, so that the power supply circuit will not have an increase in total current due to undervoltage in the AC power circuit, thereby stabilizing the current in the power supply circuit 1, meeting the reliability design of the power supply product, enabling it to operate within the design specifications, and reducing the probability of product damage. At the same time, reducing the power of the backlight LED module 5 can also alleviate the overload condition of the power grid, so that the output voltage provided by the AC power circuit approaches the normal value.

[0078] In one embodiment, in step S302, determining the first control voltage according to the sampled voltage includes: based on , obtain the first control voltage; wherein, U3 'is the first control voltage; Po is the output power of the audio and video module 6 under the standard output voltage of the mains circuit; Pb is the output power of the backlight LED module 5 under the standard output voltage of the mains circuit; U2 is the sampling voltage; U1 is the output voltage of the rectifier module 11 under the standard output voltage of the mains circuit; K is the voltage divider constant.

[0079] As an example, if the total current output by the power module does not exceed the rated current by adjusting the power of the backlight LED module 5 when the output voltage of the mains circuit is reduced, it can be assumed that the total current of the mains circuit remains unchanged before and after the output voltage is reduced, and the following is obtained:

[0080] , (Formula 1);

[0081] Where Po is the power input to the audio and video module 6 at the standard output voltage (220V) of the mains circuit, Pb is the power input to the backlight LED module 5 at the standard output voltage of the mains circuit, Pb' is the power input to the backlight LED module 5 at the current output voltage of the mains circuit, U1 is the output voltage of the rectifier module 11 at the standard output voltage of the mains circuit, is the output voltage of the rectifier module 11 under the current output voltage of the mains circuit;

[0082] According to formula 1, we can simplify it to , (Formula 2), according to the voltage division coefficient K and the sampling voltage, Formula 2 can be further written as: , (Formula 3), where U2 is the sampling voltage;

[0083] Know , (Formula 4);

[0084] Among them, U3 is the first control voltage of the mains circuit at the standard output voltage (220V), and U3' is the first control voltage of the mains circuit at the current output voltage. If U3 is set to 3V, then according to Formula 3 and Formula 4, we can get .

[0085] As an example, the control chip 4 obtains the first rated output power Po output by the first output circuit and the second rated output power Pb output by the second output circuit under the standard output voltage of the AC power circuit, and derives the first control voltage for adjusting the power input to the backlight LED module 5 under the current output voltage condition based on the first rated output power Po of the first output circuit and the second rated output power Pb output by the second output circuit under the standard output voltage condition, and on the principle that the total current output by the power supply circuit 1 remains unchanged before and after the output voltage of the AC power circuit changes. The control chip 4 is based on the obtained sampling voltage, the voltage division constant of the sampling circuit 3, the output voltage of the rectifier module 11 under the standard output voltage of the AC power circuit, the first rated output power output by the first output circuit, and the second rated output power output by the second output circuit, according to the formula , calculate and obtain the first control voltage, so that the power of the backlight LED module 5 adjusted according to the first control voltage can follow the current output voltage change of the mains circuit, so as to ensure that the total current output by the power supply circuit 1 does not exceed the rated current.

[0086] In one embodiment, if Figure 4 As shown, in step S303, a driving control signal is generated based on the first control voltage, including:

[0087] S401: Acquire a second control voltage output by an ambient light detection module;

[0088] S402: if the first control voltage is greater than or equal to the second control voltage, generating a driving control signal according to the second control voltage;

[0089] S403: If the first control voltage is less than the second control voltage, generating a driving control signal according to the first control voltage.

[0090] As an example, in step S401, the control chip 4 obtains the second control voltage output by the ambient light detection module 7. The second control voltage is the voltage obtained by the ambient light detection module 7 according to the current ambient light intensity. The second control voltage is proportional to the ambient light intensity and can increase with the increase of the ambient light intensity. The maximum value does not exceed the first preset voltage value (for example, 3V) and the minimum value does not fall below the second preset voltage value (for example, 1.5V). At the same time, the second control voltage is also another reference voltage for the control chip 4 to obtain the drive control signal. The control chip 4 can generate a drive control signal (PWM signal) of corresponding amplitude according to the magnitude of the second control voltage and output it to the drive chip connected to the backlight LED module 5, so that the drive chip adjusts the output power of the first DC-DC conversion module 12 according to the drive control signal, and finally makes the brightness of the backlight LED module 5 match the current ambient light intensity.

[0091] As an example, in step S402 and step S403, after obtaining the first control voltage and the second control voltage, the control chip 4 can compare the first control voltage and the second control voltage. When the first control voltage is greater than or equal to the second control voltage, it proves that the current ambient light intensity can allow the backlight LED module 5 to work at a lower output power. At the same time, since the first control voltage is greater than or equal to the second control voltage, the power of the backlight LED module 5 adjusted according to the second control voltage can also adapt to the supply capacity of the mains circuit, and the total current output by the power supply circuit 1 will not exceed the rated current. Therefore, the control chip 4 can give priority to brightness matching and generate a drive control signal according to the lower second control voltage. So that the first drive circuit 2 controls the backlight LED module 5 to work at a lower output power according to the drive control signal to match the current ambient light intensity, and prevent the backlight LED module 5 from being too high in power, causing glare or wasting electricity, and other undesirable conditions. When the first control voltage is less than the second control voltage, it proves that the output voltage of the current AC power circuit has dropped and is less than 220V. To prevent overcurrent and ensure that the total current output by the power supply circuit 1 does not exceed the rated current, the control chip 4 no longer prioritizes brightness matching, but generates a drive control signal based on the first control voltage, appropriately reduces the brightness of the backlight LED module 5, adapts to special situations, and ensures the normal operation of the equipment.

[0092] In this example, the control chip 4 can make a comprehensive judgment based on the second control voltage output by the ambient light detection module 7, and finally select one of the first control voltage and the second control voltage to generate a drive control signal. It can comprehensively consider the ambient light intensity and the grid load conditions, and reasonably reduce the brightness of the backlight LED module 5, thereby achieving the effect of saving power, preventing the total current from being too high, and alleviating grid overload conditions.

[0093] An embodiment of the present invention also provides a display device, including a backlight LED module 5, an audio and video module 6 and a power supply circuit in any of the above embodiments, wherein a control chip 4 can run a control method for a power supply circuit in any of the above embodiments; the audio and video module 6 and the backlight LED module 5 are connected to a power supply circuit 1.

[0094] As an example, the display device includes a backlight LED module 5, an audio and video module 6, and a power supply circuit in any of the above examples. The control chip 4 can run a control method for the power supply circuit in any of the above embodiments; the audio and video module 6 is connected to the power supply circuit 1 and is also connected to the control chip 4, and is used to work under the control of the control chip 4. The backlight LED module 5 is connected to the power supply circuit 1, and is connected to the control chip 4 through the first drive circuit 2, and is used to work under the drive of the first drive circuit 2. In this example, the control chip 4 can adjust the power of the backlight LED module 5 according to the sampling voltage, and can keep the total current input to the backlight LED module 5 and the audio and video module 6 stable by reducing the power of the backlight LED module 5 when the output voltage provided by the mains circuit decreases, so that the power supply circuit will not increase the total current due to the undervoltage of the mains circuit, stabilize the current in the power supply circuit 1, meet the reliability design of the power supply product, so that it can operate within the design specifications, and reduce the probability of product damage. At the same time, controlling the reduction of the power of the backlight LED module 5 can also play a role in alleviating the overload condition of the power grid, so that the output voltage provided by the mains circuit approaches the normal value.

[0095] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A power supply circuit, characterized in that: It includes a power supply circuit, a first driving circuit, a sampling circuit, a control chip and an ambient light detection module; The input end of the power supply circuit is used to connect to the mains circuit, and the output end of the power supply circuit is used to connect to the backlight LED module and the audio and video module; The first end of the sampling circuit is connected to the power supply circuit for obtaining a sampling voltage; The control chip is connected to the sampling circuit and is used to generate a first control voltage according to the sampling voltage when the sampling voltage meets the voltage drop evaluation condition; The ambient light detection module is connected to the control chip and is used to output a second control voltage to the control chip according to the detected ambient light intensity; The control chip is connected to the first drive circuit, and is further used to generate a drive control signal according to the second control voltage when the first control voltage is greater than or equal to the second control voltage, and to generate a drive control signal according to the first control voltage when the first control voltage is less than the second control voltage, and output the drive control signal to the first drive circuit; The first driving circuit is connected to the power supply circuit and is used to adjust the power input to the backlight LED module based on the driving control signal so that the total current output by the power supply circuit does not exceed the rated current.

2. The power supply circuit according to claim 1, characterized in that: The power supply circuit includes a rectifier module, a first DC-DC conversion module and a second DC-DC conversion module; The input end of the rectifier module is used to connect to the mains circuit; The first DC-DC conversion module and the second DC-DC conversion module are connected in parallel to the output end of the rectifier module; The first DC-DC conversion module is connected to the output end of the rectifier module and the backlight LED module; The second DC-DC conversion module is connected to the output end of the rectifier module and the audio and video module; The first drive circuit is connected to the first DC-DC conversion module, and is used to adjust the output power of the first DC-DC conversion module based on the drive control signal so that the total current output by the rectifier module does not exceed the rated current.

3. The power supply circuit according to claim 2, characterized in that: The first driving circuit includes a driving chip; The control end of the driving chip is connected to the control chip, and the driving end of the driving chip is connected to the first DC-DC conversion module, and is used to adjust the output power of the first DC-DC conversion module based on the driving control signal.

4. The power supply circuit according to claim 2, characterized in that: The sampling circuit includes a voltage dividing module and an isolation module; The voltage dividing module is connected to the output end of the rectifier module and is used to obtain a sampled voltage; The first end of the isolation module is connected to the voltage dividing module, and the second end of the isolation module is connected to the control chip, and is used to output the sampling voltage to the control chip.

5. The power supply circuit according to claim 2, characterized in that: The power supply circuit also includes an EMI module and a PFC module; The first end of the EMI module is used to connect to the mains circuit, and the second end of the EMI module is connected to the rectifier module; A first end of the PFC module is connected to the rectifier module, and a second end of the PFC module is connected to the first DC-DC conversion module and the second DC-DC conversion module.

6. A method for controlling a power supply circuit, characterized in that: Applicable to the power supply circuit according to any one of claims 1 to 5, the control method comprises: Get the sample voltage; When the sampled voltage is less than a preset voltage threshold, it is determined that a voltage drop evaluation condition is met, and a first control voltage is determined according to the sampled voltage; Acquire a second control voltage output by the ambient light detection module; If the first control voltage is greater than or equal to the second control voltage, a driving control signal is generated based on the second control voltage; if the first control voltage is less than the second control voltage, a driving control signal is generated based on the first control voltage; A driving control signal is output to the first driving circuit, so that the first driving circuit adjusts the power input to the backlight LED module according to the driving control signal, so that the total current output by the power supply circuit does not exceed the rated current.

7. The control method of the power supply circuit according to claim 6, characterized in that: The step of determining a first control voltage according to the sampled voltage comprises: based on , obtaining the first control voltage; Among them, U3' is the first control voltage; Po is the output power of the audio and video module under the standard output voltage of the AC circuit; Pb is the output power of the backlight LED module under the standard output voltage of the AC circuit; U2 is the sampling voltage; U1 is the output voltage of the rectifier module under the standard output voltage of the AC circuit; K is the voltage divider constant.

8. A display device, characterized in that: It comprises a backlight LED module, an audio and video module and a power supply circuit as claimed in any one of claims 1 to 5, wherein the control chip can run a control method for the power supply circuit as claimed in any one of claims 6 to 7; The audio and video module and the backlight LED module are connected to the power supply circuit.

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