Display device and display control method

Abstract

The application provides a display device and a display control method. The display device comprises a transformer, a voltage conversion module, a feedback module and a lamp string group. The voltage conversion module corresponds to the lamp string group one by one, and the lamp string group comprises a first lamp string and a second lamp string. A first secondary coil of the transformer outputs a first voltage. Two ends of a second secondary coil of the transformer alternately output a second voltage. The second secondary coil corresponds to the lamp string group one by one. The voltage conversion module generates a superimposed voltage according to the first voltage, superimposes the superimposed voltage on the second voltage, and outputs a third voltage. The feedback module is used for generating a feedback signal and sending the feedback signal to the voltage conversion module to adjust the third voltage. The first lamp string is connected to one end of the second secondary coil, the second lamp string is connected to the other end of the second secondary coil, and the first lamp string and the second lamp string are used for emitting light based on the third voltage. In the application, the two lamp strings share the same power supply coil and voltage conversion module, and the circuit is simplified. Meanwhile, the voltage superposition is used to realize step power supply, and the heat loss is reduced.

Description

Technical Field

[0001] This application relates to the field of display device technology, and in particular to a display device and a display control method. Background Technology

[0002] With the development of electronic technology, electronic devices, including televisions and other display devices, are becoming increasingly integrated, which places higher and higher demands on the power supply of these display devices.

[0003] Taking a television as an example, the system design is relatively complex due to the dual power supply requirements of the mainboard and the backlight drive for the LED strings. Specifically, one related design uses a resonant converter circuit (LLC) module to output multiple DC voltages based on AC power, supplying power to both the mainboard and the LED strings. Each LED string corresponds to a DC-DC voltage adjustment module, which adjusts the fixed DC voltage output by the LLC module to meet the voltage requirements of the LED string. Another related design uses two LLC modules to supply power to both the mainboard and the LED strings. In this design, the AC voltage of the primary winding in the LLC module corresponding to each LED string is adjusted, thereby regulating the output voltage of its secondary winding to meet the voltage requirements of the LED string.

[0004] Therefore, how to simplify the power supply circuit described above is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application provides a display device and a display control method to simplify the power supply circuit of the display device.

[0006] In a first aspect, this application provides a display device, comprising: a transformer, a voltage conversion module, a feedback module, and a string of lights; wherein, the voltage conversion module corresponds one-to-one with the string of lights, and the string of lights includes a first string of lights and a second string of lights; the transformer has a primary coil and a secondary coil coupled to the primary coil of the transformer; the primary coil is used to output a first voltage based on the power received by the primary coil; the secondary coil is used to alternately output a second voltage from its two ends based on the power received by the primary coil; the secondary coil corresponds one-to-one with the string of lights; the voltage conversion module is used to generate a superimposed voltage based on the first voltage and superimpose the superimposed voltage onto the second voltage at the two ends of the corresponding secondary coil, and output the superimposed third voltage; the feedback module is used to generate a feedback signal based on the output current of the string of lights and send it to the voltage conversion module, the feedback signal being used to instruct the voltage conversion module to adjust the third voltage; the first string of lights is connected to one end of the corresponding secondary coil, and the second string of lights is connected to the other end of the corresponding secondary coil, for emitting light based on the third voltage.

[0007] In some embodiments, the voltage conversion module includes: a voltage adjustment module and a voltage superposition module; the voltage adjustment module is connected to the output terminal of the first primary coil and is used to generate a superposition voltage based on the first voltage; the voltage superposition module receives the superposition voltage and is connected to both ends of the second primary coil and is used to superimpose the superposition voltage onto the second voltage at the corresponding ends of the second primary coil and output the superimposed third voltage; wherein, the feedback signal is used to instruct the voltage adjustment module to adjust the third voltage by adjusting the superposition voltage.

[0008] In some embodiments, the voltage superposition module includes a first current-sharing capacitor, a first rectifier diode, a second rectifier diode, a third rectifier diode, and a fourth rectifier diode; one end of the first current-sharing capacitor is connected to one end of the second stage coil; the other end of the first current-sharing capacitor is connected to the anode of the first rectifier diode and the cathode of the second rectifier diode; the anode of the second rectifier diode is connected to the superposition voltage; the cathode of the first rectifier diode is connected to the anode of the first lamp string; the cathode of the first lamp string is grounded; the anode of the third rectifier diode is connected to the other end of the second stage coil and the cathode of the fourth rectifier diode, and the anode of the fourth rectifier diode is connected to the superposition voltage; the cathode of the third rectifier diode is connected to the anode of the second lamp string; the cathode of the second lamp string is grounded.

[0009] In some embodiments, the voltage adjustment module includes: a second transistor, a third transistor, a second inductor, and a second capacitor; one end of the second transistor is connected to the output terminal of the primary coil; the other end of the second transistor is connected to one end of the third transistor and one end of the second inductor; the other end of the third transistor is grounded; the other end of the second inductor serves as the output terminal of the voltage adjustment module, outputting a superimposed voltage; one end of the second capacitor is connected to the other end of the second inductor; the other end of the second capacitor is grounded; the control electrodes of the second transistor and the third transistor are both connected to a feedback module, used to adjust the switching frequency of the second transistor and the third transistor according to the feedback signal, so as to adjust the superimposed voltage.

[0010] In some embodiments, the voltage adjustment module further includes a second diode; the negative terminal of the second diode is connected to one end of the second capacitor; and the positive terminal of the second diode is connected to the other end of the second capacitor.

[0011] In some embodiments, the display device further includes a first switching circuit and a first grounding resistor; the first switching circuit is located between the lamp string group and the first grounding resistor; one end of the first switching circuit is connected to the negative terminal of the first lamp string and the negative terminal of the second lamp string, and the other end of the first switching circuit is connected to one end of the first grounding resistor and the input terminal of the feedback module; the other end of the first grounding resistor is grounded; the first switching circuit is turned on or off based on the duty cycle control signal.

[0012] In some embodiments, the display device further includes: a second switching circuit and a second grounding resistor; the second switching circuit is located between the lamp string group and the second grounding resistor; one end of the second switching circuit is connected to the negative terminal of the first lamp string and the negative terminal of the second lamp string, and the other end of the second switching circuit is connected to one end of the second grounding resistor; the other end of the second grounding resistor is grounded; the second switching circuit is used to change the loop current to simulate dimming during the dimming process.

[0013] In some embodiments, the second switching circuit includes: a fifth transistor and a comparator; one end of the fifth transistor is connected to the negative terminal of the first lamp string and the negative terminal of the second lamp string; the other end of the fifth transistor is connected to one end of the second grounding resistor and the inverting input terminal of the comparator; the non-inverting input terminal of the comparator receives the required voltage of the lamp string group, and the output terminal of the comparator is connected to the gate of the fifth transistor; adjusting the resistance value of the fifth transistor is used to change the loop current and perform analog dimming.

[0014] In some embodiments, the number of secondary coils, voltage conversion modules, and lamp string groups are all multiple; the display device also includes multiple current sharing inductors; and a current sharing inductor coupled to each other is provided between two adjacent secondary coils.

[0015] In some embodiments, the display device further includes a motherboard; the transformer further includes a third-stage coil coupled to the primary coil; the third-stage coil is used to output a fourth voltage according to the power received by the primary coil; the first voltage output by the first-stage coil and the fourth voltage output by the third-stage coil both power the motherboard.

[0016] Secondly, this application provides a display control method applied to a display device as described in the first aspect. The display control method includes: receiving a feedback signal, wherein the feedback signal is generated by a feedback module based on the output current of a string of lights; and adjusting a third voltage based on the feedback signal; wherein the third voltage is the operating voltage of the string of lights.

[0017] The display device and display control method provided in this application include: a transformer, a voltage conversion module, a feedback module, and a string of lights; the voltage conversion module corresponds one-to-one with the string of lights, and the string of lights includes a first string of lights and a second string of lights; the primary coil of the transformer outputs a first voltage; the two ends of the secondary coil of the transformer alternately output a second voltage; the secondary coil corresponds one-to-one with the string of lights; the voltage conversion module generates a superimposed voltage based on the first voltage, and superimposes the superimposed voltage onto the second voltage to output a third voltage; the feedback module generates a feedback signal and sends it to the voltage conversion module to adjust the third voltage; the first string of lights is connected to one end of the secondary coil, and the second string of lights is connected to the other end of the secondary coil, for emitting light based on the third voltage. In this application, the two string of lights share the same power supply coil and voltage conversion module, simplifying the circuit; at the same time, the use of voltage superposition to achieve stepped power supply helps to reduce heat loss. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] Figure 1 A schematic diagram of a display device with an independent power supply board;

[0020] Figure 2 This is a schematic diagram showing the connection relationship between the power board and the load of the display device.

[0021] Figure 3 This is a schematic diagram of a TV power supply architecture.

[0022] Figure 4 This is a schematic diagram of a circuit structure for powering a motherboard and an LED string;

[0023] Figure 5 This is a schematic diagram of another circuit structure for powering the motherboard and LED strings;

[0024] Figure 6 This is a schematic diagram of another circuit structure for powering the motherboard and LED strings;

[0025] Figure 7 A circuit structure diagram of a two-channel light string display device provided in an embodiment of this application;

[0026] Figure 8 A schematic diagram of the circuit structure of a voltage conversion module provided in an embodiment of this application;

[0027] Figure 9 A schematic diagram of the circuit structure of a voltage superposition module provided in an embodiment of this application;

[0028] Figure 10A circuit structure diagram of a voltage adjustment module provided in an embodiment of this application;

[0029] Figure 11 A schematic diagram of the circuit structure of another voltage adjustment module provided in an embodiment of this application;

[0030] Figure 12 A schematic diagram of the circuit structure of a first switching circuit provided in an embodiment of this application;

[0031] Figure 13 A schematic diagram of the circuit structure of a second switching circuit provided in an embodiment of this application;

[0032] Figure 14 A schematic diagram of the circuit structure of a four-channel LED string display device provided in an embodiment of this application;

[0033] Figure 15 A schematic diagram of the circuit structure of another four-channel light string display device provided in an embodiment of this application;

[0034] Figure 16 A schematic diagram of the circuit structure of another four-channel light string display device provided in an embodiment of this application;

[0035] Figure 17 A schematic diagram of the circuit structure of another four-channel light string display device provided in this application embodiment.

[0036] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0037] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application.

[0038] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] The following section, with reference to the accompanying drawings, explains the application scenario and existing problems of this application. As people's need for information acquisition continues to deepen, various types of display devices have emerged, such as computers, televisions, and projectors. The power supply circuit is one of the most important circuit structures in a display device, providing electrical energy to enable its normal operation. Some display devices have a separate power board, while others combine the power board and mainboard into one.

[0040] Taking a display device with an independent power supply board as an example, the structure of the display device will be explained. See [link / reference]. Figure 1 As shown, Figure 1 This is a schematic diagram of a display device with an independent power supply board, such as... Figure 1 As shown, the display device includes a display panel 1, a backlight assembly 2, a motherboard 3, a power board 4, a back cover 5, and a base 6. The display panel 1 is used to present images to the user. The backlight assembly 2, located below the display panel 1, typically consists of optical components that provide sufficient brightness and a uniformly distributed light source, enabling the display panel 1 to display images correctly. The backlight assembly 2 also includes a back plate 20, on which the motherboard 3 and power board 4 are mounted. Typically, raised structures are stamped into the back plate 20, and the motherboard 3 and power board 4 are fixed to these raised structures with screws or hooks. The back cover 5 covers the panel 1 to conceal the backlight assembly 2, motherboard 3, power board 4, and other components of the display device, achieving an aesthetically pleasing effect. The base 6 supports the display device.

[0041] In some embodiments, Figure 2 This is a schematic diagram showing the connection relationship between the power board and the load of the display device, as shown below. Figure 2As shown, the power board 4 includes an input terminal 41 and an output terminal 42 (first output terminal 421, second output terminal 422, and third output terminal 423 are shown in the figure). The input terminal 41 is connected to AC mains power, and the output terminal 42 is connected to the load. For example, the first output terminal 421 is connected to an LED string used to light up the display screen, the second output terminal 422 is connected to the speakers, and the third output terminal 423 is connected to the motherboard. The power board 4 needs to convert AC mains power into DC power required by the load, and this DC power typically has different specifications; for example, speakers require 18V, and the panel requires 12V.

[0042] In some embodiments, the power architecture of a display device is described using a television as an example. Figure 3 This is a schematic diagram of a TV power supply architecture, such as... Figure 3 As shown, the power supply board may specifically include: a rectifier bridge, a power factor correction (PFC) module, and a resonant converter (LLC) module. The LLC module includes a synchronous rectification circuit. Figure 3 (Not shown), the PFC module is connected to the LLC module, and the LLC module is connected to the load.

[0043] The rectifier bridge rectifies the input AC mains power, supplying a full-wave signal to the PFC module. An electromagnetic interference (EMI) filter can be connected before the AC power input to the PFC module. Figure 3 (Not shown), performs high-frequency filtering on the input AC power supply.

[0044] A PFC module may include a PFC inductor, switching power devices, and a PFC control chip. Its main function is to perform power factor correction on the input AC power supply and output a stable DC bus voltage (e.g., 380V) to the LLC module. The PFC module can effectively improve the power factor of the power supply and ensure that voltage and current are in phase. Alternatively, in some embodiments, such as... Figure 3 The power architecture shown may also omit the PFC module.

[0045] The LLC module can employ a dual-MOSFET LLC resonant converter circuit. Typically, a synchronous rectification circuit is incorporated within the LLC module, which mainly includes a transformer, a controller, two MOSFETs, and diodes. Additionally, the LLC module may include a pulse frequency modulation (PFM) circuit, capacitors, and inductors. Specifically, the LLC module can step down or boost the DC bus voltage input to the PFC module and output a constant voltage to the load. Generally, the LLC module can output multiple different voltages to meet the needs of different loads. Alternatively, in other embodiments, such as... Figure 3 The LLC module shown can also be replaced by a flyback voltage converter module, which steps down or boosts the voltage and outputs a constant voltage to the load.

[0046] More specifically, taking a television set as an example again, Figure 4 This is a schematic diagram of a power supply circuit structure for powering a motherboard and LED strings. The AC mains power (100V-240V, 50-60Hz) obtained by the power supply circuit passes sequentially through a filter and rectifier module (rectifier bridge), a PFC module, and an LLC isolation voltage converter module before being supplied to the motherboard of the display device, the multi-channel LED strings, and other loads. Figure 4 (Not shown in the diagram) Power supply. In the LLC isolated voltage conversion module, the first secondary winding provides a first voltage (e.g., 12V) to the motherboard, the second secondary winding provides a second voltage (e.g., 18V) to the motherboard, and the third secondary winding simultaneously provides voltage to the multi-channel LED string.

[0047] LED strings are used to light up the display screen of a television. The LED components in the LED string need to operate within a certain voltage drop range to achieve their rated current. For example, in a multi-channel LED string with 16 channels and each channel containing 9 LED components, the required voltage range for the multi-channel LED string is 51.3V-58.5V, and the total current is 1.92A under 120mA conditions.

[0048] Because the operating voltage of LED light strings is affected by factors such as the working environment, the hardware characteristics of the LED components, and their lifespan, it needs to be adjusted in real time. Therefore, the power supply circuit also includes a voltage regulation module (a buck converter, a boost converter, or a buck-boost converter). This module can detect the operating voltage or current of the LED light strings and send feedback signals to the voltage regulation module based on changes in the operating voltage or current. This allows the voltage regulation module to adjust the voltage output to the LED light strings according to the feedback signals, thereby maintaining a stable operating current for the LED light strings.

[0049] like Figure 4 As shown, taking the power supply for the motherboard and two LED strings as an example, each LED string is equipped with a voltage adjustment module, using a boost converter circuit as an example. The voltage adjustment module adjusts the fixed voltage output from the third secondary winding based on the real-time current feedback of each LED string before transmitting it to each LED string. This ensures that each LED string operates at its rated current, preventing excessive current from flowing through the LED components and causing damage.

[0050] However, in such Figure 4The power supply circuit shown includes a voltage adjustment module for each LED string. This means that an additional voltage adjustment module is needed for each new LED string. Therefore, the circuit structure is relatively complex, occupying a larger area on the PCB board where the power supply circuit is located, ultimately increasing the cost of the power supply circuit.

[0051] In some embodiments, Figure 5 This is a schematic diagram of another circuit structure for powering the motherboard and LED strings. The AC mains power (100V-240V, 50-60Hz) obtained by the power supply circuit passes sequentially through a filter and rectifier module (rectifier bridge), a PFC module, and an LLC isolation voltage conversion module before being supplied to the motherboard of the display device, the multi-channel LED strings, and other loads. Figure 5 (Not shown in the diagram) Power supply. In LLC isolated voltage conversion module 1, the first secondary winding provides a first voltage (e.g., 12V) to the main board, and the second secondary winding provides a second voltage (e.g., 18V) to the main board. LLC isolated voltage conversion module 2 simultaneously provides voltage to both LED strings. LLC isolated voltage conversion module 2 utilizes the characteristics of alternating current to alternately provide operating voltage to the two LED strings. The controller of LLC isolated voltage conversion module 2 receives current feedback from the two LED strings and adjusts the voltage output of LLC isolated voltage conversion module 2. The adjusted voltage is then transmitted to the two LED strings, ensuring that each LED string operates at its rated current, preventing excessive current from flowing through the LED components and causing damage.

[0052] In this module, the capacitor connected to one output terminal of the secondary winding of the LLC isolation voltage conversion module 2 serves as a current sharing device to ensure that the operating current of the two LED strings is equal. The diodes connected in series between the two output terminals of the secondary winding and the LED strings serve as rectification devices based on their unidirectional conduction characteristics. The grounding diodes connected to the two output terminals of the secondary winding serve as voltage regulators.

[0053] However, in Figure 5 In the power supply circuit shown, the output voltage range of LLC isolated voltage converter module 2 is limited. When it is necessary to change the current magnitude, the output range of LLC isolated voltage converter module 2 is significantly restricted. Additionally, the display device may have more than two LED strings, according to... Figure 5 As shown in the power supply circuit, for every two additional LED strings, a secondary winding needs to be added to the LLC isolation voltage converter module 2 to power the new LED strings. A large number of secondary windings makes transformer design relatively difficult, and the complex circuitry also increases costs.

[0054] In some embodiments, Figure 6This is a schematic diagram of another circuit structure for powering the motherboard and LED strings. The AC mains power (100V-240V, 50-60Hz) obtained by the power supply circuit passes sequentially through a filter and rectifier module (rectifier bridge), a PFC module, and an LLC isolation voltage converter module before being supplied to the motherboard of the display device, the multi-channel LED strings, and other loads. Figure 6 Power supply (not shown). The LLC isolated voltage conversion module includes four secondary windings. The first secondary winding provides a first voltage (e.g., 12V) to the main board, and the second secondary winding provides a second voltage (e.g., 18V) to the main board. The second and third secondary windings together power the second LED string. The second and fourth secondary windings together power the first LED string.

[0055] Specifically, the 18V output voltage of the second secondary winding is used by a voltage adjustment module, such as a boost circuit, to generate a "variable voltage", which is connected to one end of the third secondary winding and superimposed with the fixed voltage 2 generated by the third secondary winding. The superimposed voltage powers the second LED string.

[0056] Similarly, the 18V output voltage of the second secondary winding is used by a voltage adjustment module, such as a boost circuit, to generate a "variable voltage", which is connected to one end of the fourth secondary winding and superimposed with the fixed voltage 1 generated by the fourth secondary winding. The superimposed voltage powers the first LED string.

[0057] exist Figure 6 In the power supply circuit shown, the method of superimposing "variable voltage" and "fixed voltage" is called "stepped power supply." This method helps reduce the voltage withstand requirements of components such as switching transistors and capacitors in the voltage regulation module, thereby reducing costs. However, for each additional LED string, a secondary winding and a corresponding voltage regulation module need to be added to the LLC isolated voltage conversion module. A large number of secondary windings makes transformer design relatively difficult; at the same time, the circuit structure is relatively complex, thus occupying a larger area on the PCB board where the power supply circuit is located, ultimately increasing the cost of the power supply circuit.

[0058] Based on this, the display device provided in this application uses a single secondary coil and voltage conversion module for two LED strings. The secondary coil alternately outputs a fixed voltage, which is superimposed on the variable voltage output by the voltage conversion module, thus achieving a stepped power supply to the two LED strings. This simplifies the power supply circuit and reduces heat loss.

[0059] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0060] Figure 7 This is a schematic diagram of the circuit structure of a two-channel LED string display device provided in an embodiment of this application. Figure 7 As shown, it includes: a transformer, a voltage conversion module, a feedback module, and a string of lights; wherein, the voltage conversion module corresponds one-to-one with the string of lights, and the string of lights includes a first string of lights 140 and a second string of lights 150.

[0061] Figure 7 Taking the LLC isolation voltage conversion module as an example, the first stage coil 110 and the second stage coil 120 of the LLC isolation voltage conversion module are coupled to the primary coil 100 of the LLC isolation voltage conversion module. The first stage coil 110 is used to output a first voltage based on the power received by the primary coil 100. The second stage coil 120 is used to alternately output a second voltage from its two ends based on the power received by the primary coil 100. The second stage coil 120 corresponds one-to-one with the lamp string group. The voltage conversion module is used to generate a superimposed voltage based on the first voltage and superimpose the superimposed voltage onto the second voltage at the two ends of the corresponding second stage coil, and output the superimposed third voltage.

[0062] The feedback module is used to generate a feedback signal based on the output current of the light string group and send it to the voltage conversion module. The feedback signal is used to instruct the voltage conversion module to adjust the third voltage. The first light string 140 is connected to one end of the corresponding secondary coil 120, and the second light string 150 is connected to the other end of the corresponding secondary coil 120 for emitting light based on the third voltage.

[0063] in, Figure 7 The power supply circuit shown also includes a filter and rectifier module (rectifier bridge) and a PFC module, which process the acquired AC mains power and then supply it to the motherboard of the display device, the multi-channel LED string, and other loads via an LLC isolation voltage converter module. Figure 7 Power supply (not shown in the image).

[0064] In this system, one end of the primary coil 110 is grounded, and a rectifier diode is connected in series with the middle tap of the primary coil 110 and the other end of the primary coil 110 to output the first voltage. Figure 7 The first voltage is taken as 18V DC voltage. Because the coupling between the primary coil 110 and the primary coil 100 generates AC current, it needs to be converted from AC to DC through the above-mentioned rectifier circuit.

[0065] This embodiment utilizes the alternating current induced by the coupling between the secondary coil 120 and the primary coil 100 to alternately output a second voltage, equivalent to a "fixed voltage." The voltage conversion module adjusts the first voltage output by the primary coil based on the feedback signal to generate a superimposed voltage, equivalent to a "variable voltage." The voltage conversion module then adds this superimposed voltage to the second voltage, outputting the superimposed third voltage. In this embodiment, the two light strings share the same power supply coil and voltage conversion module, simplifying the circuit. Simultaneously, the superposition of the "fixed voltage" and the "variable voltage" achieves stepped power supply, which helps reduce heat loss.

[0066] The feedback module can be either current feedback or voltage feedback. It can generate a feedback signal based on the current of a single LED string or multiple LED strings. When using a single LED string for feedback, the reference current value set in the feedback module is the required operating current of that single LED string. When two LED strings provide feedback together, the reference current value set in the feedback module is twice the required operating current of one LED string. This reference current value is compared with the actual current. If the actual current is higher than the reference current value, the output feedback signal instructs the voltage adjustment module to reduce the third voltage; if the actual current is equal to the reference current value, the output feedback signal instructs the voltage adjustment module to maintain the third voltage; if the actual current is lower than the reference current value, the output feedback signal instructs the voltage adjustment module to increase the third voltage.

[0067] Figure 7 A dual-channel feedback method is employed. Specifically, the feedback module generates a feedback signal based on the total current of the first LED string 140 and the second LED string 150 in the LED string group, and sends it to the voltage conversion module to instruct the voltage conversion module to adjust the third voltage. The first LED string 140 and the second LED string 150 can be directly grounded or grounded through a grounding circuit Rn. The grounding circuit Rn facilitates the release of static electricity and prevents static accumulation.

[0068] In some embodiments, Figure 8 This is a schematic diagram of the circuit structure of a voltage conversion module provided in an embodiment of this application. The voltage conversion module includes a voltage adjustment module and a voltage superposition module; the voltage adjustment module is connected to the output terminal of the first stage coil and is used to generate a superimposed voltage based on the first voltage; the voltage superposition module receives the superimposed voltage and is connected to both ends of the second stage coil, and is used to superimpose the superimposed voltage onto the second voltage at the corresponding ends of the second stage coil, and output the superimposed third voltage; wherein, a feedback signal is used to instruct the voltage adjustment module to adjust the third voltage by adjusting the superimposed voltage.

[0069] The second voltage is equivalent to a "fixed voltage." The voltage adjustment module adjusts the first voltage based on the feedback signal and outputs a superimposed voltage, which is equivalent to a "variable voltage." The voltage superposition module adds this superimposed voltage to the second voltage and outputs the superimposed third voltage to power the string of lights. This stepped power supply method helps reduce heat loss.

[0070] In some embodiments, the voltage superposition module includes a first current sharing capacitor C1, a first rectifier diode D1, a second rectifier diode D2, a third rectifier diode D3, and a fourth rectifier diode D4.

[0071] One end of the first current-sharing capacitor C1 is connected to one end of the second stage coil; the other end of the first current-sharing capacitor C1 is connected to the positive terminal of the first rectifier diode D1 and the negative terminal of the second rectifier diode D2; the positive terminal of the second rectifier diode D2 is connected to the superimposed voltage; the negative terminal of the first rectifier diode D1 is connected to the positive terminal of the first lamp string 140; the negative terminal of the first lamp string 140 is grounded.

[0072] The positive terminal of the third rectifier diode D3 is connected to the other end of the second stage coil 120 and the negative terminal of the fourth rectifier diode D4. The positive terminal of the fourth rectifier diode D4 is connected to the superimposed voltage. The negative terminal of the third rectifier diode D3 is connected to the positive terminal of the second lamp string 150. The negative terminal of the second lamp string 150 is grounded.

[0073] Figure 9 This is a schematic diagram of the circuit structure of a voltage superposition module provided in an embodiment of this application. When the primary coil 100 is turned on and off under the internal control of the LLC isolated voltage conversion module, the first current sharing capacitor C1 undergoes charging and discharging processes respectively.

[0074] When the first current-sharing capacitor C1 discharges, the current flows from the first terminal of the first current-sharing capacitor C1 (i.e., Figure 10 The left end of the first current-sharing capacitor C1 shown is connected to the second end (i.e., Figure 10 The current flows through the right end of the first current-sharing capacitor C1, and the charge in the first current-sharing capacitor C1 is released through the circuit of the first lamp string 140. At the same time, the superimposed voltage output by the voltage adjustment module is input to the positive terminal of the first rectifier diode D1 through the second rectifier diode D2. Current superposition occurs at the positive terminal of the first rectifier diode D1, and is input to the first lamp string 140 through the negative terminal of the first rectifier diode D1.

[0075] When the first current-sharing capacitor C1 is charging, current flows from the second terminal to the first terminal of the first current-sharing capacitor C1, and the third rectifier diode D3 is turned on. The charge in the first current-sharing capacitor C1 is released through the circuit of the second lamp string 150. At the same time, the superimposed voltage output by the voltage adjustment module is input to the positive terminal of the third rectifier diode D3 through the fourth rectifier diode D4. Current superposition occurs at the positive terminal of the third rectifier diode D3, and is input to the second lamp string 150 through the negative terminal of the third rectifier diode D3.

[0076] Since the total charge is equal during the charging and discharging of the current-sharing capacitor, the charge flowing through the two LED strings is equal, resulting in equal currents in both strings, thus achieving current sharing. If the currents in the two strings are unequal, a voltage difference will be generated across the first current-sharing capacitor C1, making the loop voltage drop of the first LED string 140 and the second LED string 150 the same, i.e., balancing the impedance. After several cycles, the current reaches an equal equilibrium state again. Therefore, over a long period of time, the current in the two LED strings is equal.

[0077] The loop containing the first light string 140 includes the first rectifier diode D1, the first light string 140, the feedback module, the voltage adjustment module, the fourth rectifier diode D4, and the second side winding 120; the loop containing the second light string 150 includes the second side winding 120, the third rectifier diode D3, the second light string 150, the feedback module, the voltage adjustment module, and the second rectifier diode D2.

[0078] In this embodiment, the two light strings share the same power supply coil (i.e., the secondary coil 120) and voltage adjustment module, which simplifies the circuit. At the same time, the voltage is superimposed using two rectifier diodes to achieve stepped power supply to each light string, which helps to reduce heat loss.

[0079] In some embodiments, the voltage adjustment module can be a boost circuit. Specifically, the voltage adjustment module includes: a first inductor L1, a first transistor Q1, a first diode D5, and a first capacitor C2. One end of the first inductor L1 is connected to the output terminal of the primary coil 110; the other end of the first inductor L1 is connected to one end of the first transistor Q1 and the anode of the first diode D5; the other end of the first transistor Q1 is grounded; the cathode of the first diode D5 serves as the output terminal of the voltage adjustment module, outputting a superimposed voltage; one end of the first capacitor C2 is connected to the cathode of the first diode D5; the other end of the first capacitor C2 is grounded; the control electrode of the first transistor Q1 is connected to the feedback module, used to adjust the switching frequency of the first transistor Q1 according to the feedback signal, thereby adjusting the superimposed voltage.

[0080] Figure 10This is a schematic diagram of the circuit structure of a voltage adjustment module provided in an embodiment of this application. When the first transistor Q1 is turned on, the output terminal of the first primary coil 110 continuously outputs a first voltage to charge the first inductor L1, causing the current of the first inductor L1 to increase linearly.

[0081] When the first transistor Q1 is turned off, the first inductor L1 can only discharge through the first diode D5, outputting a superimposed voltage from the cathode of the first diode D5 to the second rectifier diode D2 and the fourth rectifier diode D4, while simultaneously charging the first capacitor C2; the voltage across the capacitor rises, and is higher than the input first voltage.

[0082] When the first transistor Q1 is turned on again, it charges the first inductor L1 again; at the same time, due to the unidirectional conduction of the first diode D5, the first capacitor C2 discharges, outputting a superimposed voltage to the second rectifier diode D2 and the fourth rectifier diode D4.

[0083] By controlling the switching frequency of the first transistor Q1, or by selecting a first capacitor C2 with a larger capacitance, a continuous superimposed voltage can be output, and this superimposed voltage is higher than the input first voltage. The other end of the first transistor Q1 can be directly grounded, or connected to a grounding resistor R1 to discharge static electricity and improve safety.

[0084] In some embodiments, Figure 10 A current feedback method is adopted. The feedback module includes a first driver chip, which is used to collect the actual total current of the first LED string 140 and the second LED string 150 in real time, generate a feedback signal, and enable the voltage adjustment module to adjust the voltage in a timely and effective manner to prevent excessive current from flowing through the LED components in the first LED string 140 and the second LED string 150 and causing damage to the components.

[0085] In some embodiments, the voltage adjustment module can be a buck converter circuit. Specifically, the voltage adjustment module includes: a second transistor Q2, a third transistor Q3, a second inductor L2, a second capacitor C2, and a second driver chip. One end of the second transistor Q2 is connected to the output terminal of the primary coil 110; the other end of the second transistor Q2 is connected to one end of the third transistor Q3 and one end of the second inductor L2; the other end of the third transistor Q3 is grounded; the other end of the second inductor L2 serves as the output terminal of the voltage adjustment module, outputting a superimposed voltage; one end of the second capacitor C2 is connected to the other end of the second inductor L2; the other end of the second capacitor C2 is grounded; the control terminals of the second transistor Q2 and the third transistor Q3 are both connected to a feedback module, used to adjust the switching frequencies of the second transistor Q2 and the third transistor Q3 according to the feedback signal, thereby adjusting the superimposed voltage.

[0086] Figure 11This is a schematic diagram of the circuit structure of another voltage adjustment module provided in an embodiment of this application. This voltage adjustment module is a synchronous rectification buck converter circuit. Using a third transistor Q3 instead of a rectifier diode improves voltage conversion efficiency.

[0087] When the second transistor Q2 is turned on and the third transistor Q3 is turned off, the output terminal of the primary winding 110 continuously outputs the first voltage, charging the second inductor L2 and causing the current of the second inductor L2 to increase linearly. At this time, a superimposed voltage is output to the second rectifier diode D2 and the fourth rectifier diode D4, while simultaneously charging the second capacitor C3. When the second transistor Q2 is turned off and the third transistor Q3 is turned on, the freewheeling current of the second inductor L2 discharges through the third transistor Q3, and the current of the second inductor L2 decreases linearly. At this time, a superimposed voltage is output to the second rectifier diode D2 and the fourth rectifier diode D4 through the second capacitor C3 and the gradually decreasing second inductor L2.

[0088] By controlling the switching frequencies of the second transistor Q2 and the third transistor Q3, a superimposed voltage can be continuously output, and this superimposed voltage is lower than the input first voltage. The other end of the third transistor Q3 can be directly grounded or connected to a grounding resistor R2 to discharge static electricity and improve safety.

[0089] In some embodiments, when using Figure 11 In the synchronous rectification buck converter circuit shown, the voltage adjustment module also includes a second diode D6; the negative terminal of the second diode D6 is connected to one end of the second capacitor C3; the positive terminal of the second diode D6 is connected to the other end of the second capacitor C3.

[0090] When the voltage adjustment module has no output, the second transistor Q2 is off, and the current of the lamp string group flows back to the secondary winding 120 through the body diode of the third transistor Q3, the second inductor L2, and the fourth current-sharing diode D4. When the current is too large, it will cause more heat loss in the body diode of the third transistor Q3. To reduce this loss, a new current loop is formed using the second diode D6, allowing the current of the lamp string group to flow back to the secondary winding 120 through the second diode D6 and the fourth current-sharing diode D4. The second diode D6 is a low-power diode such as a Schottky diode.

[0091] The aforementioned buck and boost topologies can be selected based on engineering needs. For example, the buck topology has the advantage of low cost, but a narrower output voltage range; while the boost topology has the advantage of a wider output voltage range, but its cost is relatively high.

[0092] In some embodiments of the display device, a first switching circuit and a first grounding resistor R3 are also included; the first switching circuit is located between the lamp string group and the first grounding resistor R3; one end of the first switching circuit is connected to the negative terminal of the first lamp string and the negative terminal of the second lamp string, and the other end of the first switching circuit is connected to one end of the first grounding resistor R3 and the input terminal of the feedback module; the other end of the first grounding resistor R3 is grounded; the first switching circuit is turned on or off based on the duty cycle control signal.

[0093] Figure 12 This is a schematic diagram of the circuit structure of a first switching circuit provided in an embodiment of this application. Figure 12 As shown, for multi-output circuits, the voltages of multiple secondary coils may exhibit cross-regulation issues. Cross-regulation refers to the impact on the output voltage of a particular output when other outputs are under load. For example, when the output voltage of the third-stage coil 130 is heavily loaded, the output voltages of the first-stage coil 110 and the second-stage coil 120 will be increased. Consequently, when the voltage conversion module is not operating, the second voltage output by the second-stage coil 120 exceeds the operating voltage of the lamp string group, causing the lamp string group to light up uncontrollably. In other words, the lighting and shutdown of the lamp string group becomes uncontrolled.

[0094] Therefore, a first switching circuit needs to be added to the loop of the light string group to ensure that the light string group is in an off state when it is not needed to emit light. For example, when the display device is in standby mode, the display screen of the display device is usually off, that is, the light string group should be in an off state. The duty cycle control signal (i.e., Figure 12 The PWM control signal shown can be synchronized with the control signal for the display device status. That is, when the display device is controlled to standby mode, the LED string group is synchronously controlled to be non-lighting by the duty cycle control signal.

[0095] In some embodiments, the first switching circuit includes: a fourth transistor Q4; one end of the fourth transistor Q4 is connected to the negative terminal of the first lamp string 140 and the negative terminal of the second lamp string 150; the other end of the fourth transistor Q4 is connected to one end of the first grounding resistor R3 and the input terminal of the feedback module; the gate of the fourth transistor Q4 is connected to a duty cycle control signal, and the fourth transistor is turned on or off based on the duty cycle control signal. (Refer to...) Figure 12 When the PWM control signal is low, the fourth transistor Q4 is turned off, so the LED string group does not light up.

[0096] In some embodiments of the display device, a second switching circuit and a second grounding resistor R4 are also included; the second switching circuit is located between the lamp string group and the second grounding resistor R4; one end of the second switching circuit is connected to the negative terminal of the first lamp string 140 and the negative terminal of the second lamp string 150, and the other end of the second switching circuit is connected to one end of the second grounding resistor R4; the other end of the second grounding resistor R4 is grounded; the second switching circuit is used to change the loop current to perform simulated dimming.

[0097] Figure 13 This is a schematic diagram of a second switching circuit provided in an embodiment of this application. Analog dimming achieves its effect of changing the brightness of the lamp string by altering the current in the lamp string circuit. For analog dimming, if the current in the lamp string is small, the required operating voltage for the lamp string is also small, making it easier for the second voltage output by the secondary coil 120 to exceed the required operating voltage of the lamp string. When the second voltage output by the secondary coil 120 remains constant, the resistance value in the circuit is adjusted through the second switching circuit, thereby changing the current in the circuit. Compared to the method of achieving dimming by adjusting the second voltage output by the secondary coil 120, the circuit design is simpler.

[0098] In some embodiments, the second switching circuit includes: a fifth transistor Q5 and a comparator; one end of the fifth transistor Q5 is connected to the negative terminal of the first lamp string 140 and the negative terminal of the second lamp string 150; the other end of the fifth transistor Q5 is connected to one end of the second grounding resistor R4 and the inverting input terminal of the comparator; the non-inverting input terminal of the comparator receives the required voltage of the lamp string group, and the output terminal of the comparator is connected to the gate of the fifth transistor Q5; adjusting the resistance value of the fifth transistor Q5 is used to change the loop current and perform analog dimming.

[0099] Reference Figure 13 The inverting input of the comparator receives the actual total current of the first lamp string 140 and the second lamp string 150. Since comparators typically compare voltage signals, the current feedback signal needs to be converted to a voltage feedback signal. The method for converting the current feedback signal to a voltage feedback signal is described in related technologies. The non-inverting input of the comparator receives a reference voltage, which is derived from the reference current. The method for converting the reference current signal to a reference voltage signal is described in related technologies. When the voltage feedback signal exceeds the reference voltage, the fifth transistor Q5 can be set to a linear operating state, absorbing the excess voltage across the fifth transistor Q5.

[0100] in, Figure 13A voltage feedback method is adopted. One end of the first feedback resistor R5 is connected to the negative terminal of the first lamp string 140 and the negative terminal of the second lamp string 150, and the other end of the first feedback resistor R5 is connected to one end of the second feedback resistor R6; the other end of the second feedback resistor R6 is grounded; the second driver chip samples from the connection point of the first feedback resistor R5 and the second feedback resistor R6, and sends the voltage feedback signal to the voltage conversion module.

[0101] The second driver chip is used to acquire the signal at the connection point of the first feedback resistor R5 and the second feedback resistor R6 in real time, generate a feedback signal, and enable the voltage conversion module to adjust the voltage in a timely and effective manner to prevent excessive current from flowing through the LED components in the first LED string 140 and the second LED string 150 and causing damage to the components.

[0102] Reference Figures 7 to 13 The display device provided in this embodiment also includes a motherboard; the transformer further includes a third-stage coil 130 coupled to the primary coil; the third-stage coil 130 is used to output a fourth voltage according to the power received by the primary coil; the first voltage output by the first-stage coil 110 and the fourth voltage output by the third-stage coil 130 both power the motherboard. For example, the first voltage is 18V and the fourth voltage is 12V.

[0103] In some embodiments of the display device, there are multiple secondary coils 120, voltage conversion modules, and LED string groups; the display device also includes multiple current sharing inductors; and a mutual coupled current sharing inductor is provided between two adjacent secondary coils.

[0104] Taking a four-way LED string as an example, Figure 14 This is a circuit diagram of a four-channel LED string display device provided in an embodiment of this application, wherein the voltage adjustment module is an example of a boost converter circuit. Figure 14 As shown, it includes two sets of LED string groups, with four LED strings: the first LED string 140, the second LED string 150, the third LED string 160, and the fourth LED string 170; and two secondary coils 120 and 121, corresponding to the two sets of LED string groups. The two secondary coils 120 and 121 are coupled with mutual current-sharing inductors: the third inductor L3 and the fourth inductor L4.

[0105] When the winding direction and number of turns of the two secondary coils 120 and 121 are the same, the current direction in the power supply circuit of the second lamp string 150 is opposite to that in the power supply circuit of the third lamp string 160 during power supply, thus generating impedance. The third inductor L3 is connected in series in the power supply circuit of the second lamp string 150, and the fourth inductor L4 is connected in series in the power supply circuit of the third lamp string 160. The third inductor L3 and the fourth inductor L4 are coupled to balance the generated impedance.

[0106] The feedback module uses four LED strings for feedback, therefore the reference current value set in the feedback module is four times the required operating current of one LED string. The principle of the newly added secondary coil 121 supplying power to the third LED string 160 and the fourth LED string 170 will not be elaborated further.

[0107] Figure 15 This is a schematic diagram of the circuit structure of another four-channel LED string display device provided in an embodiment of this application. In the power supply circuit of the four-channel LED string display device, [the circuit is connected to...] Figure 12 Similarly, the first switching circuit is located between the four light strings (first light string 140, second light string 150, third light string 160, and fourth light string 170) and the grounding resistor R3. For multi-output circuits, the voltages of multiple secondary coils may have cross-regulation issues. To prevent the second voltage output by the second secondary coil 120 or 121 from exceeding the operating voltage of the light string group when the voltage conversion module is not working, thus causing the light string group to light up, a first switching circuit is added to the circuit of the light string group to ensure that the light string group is in the off state when it is not needed to light up. Specifically, the first switching circuit includes a fourth transistor Q4. When the PWM control signal is low, the fourth transistor Q4 is turned off, so the light string group is not lit.

[0108] Figure 16 This application provides a schematic diagram of the circuit structure of another four-channel LED string display device. In the power supply circuit of the four-channel LED string display device, a second switching circuit is located between the LED string group and the grounding resistor. Through the second switching circuit, the resistance value in the circuit is adjusted, changing the current in the circuit, thereby adjusting the brightness of the LED string group. Specifically, when the actual voltage of the LED string group exceeds the reference voltage, this transistor can be set to a linear operating state to share the excess voltage and prevent excessive voltage in the LED string group, which could damage the circuit. Specifically, the second switching circuit includes a fifth transistor Q5 and a comparator. The inverting input of the comparator receives the actual total current of the first LED string 140 and the second LED string 150. Generally, the comparator compares voltage signals, so the current feedback signal needs to be converted into a voltage feedback signal. The scheme for converting the current feedback signal into a voltage feedback signal is described in related technologies. The non-inverting input of the comparator receives a reference voltage, which is derived from a reference current. The scheme for converting the reference current signal into a reference voltage signal is described in related technologies. When the voltage feedback signal exceeds the reference voltage, the fifth transistor Q5 can be set to linear operation to absorb the excess voltage on the fifth transistor Q5.

[0109] Figure 17 This is a schematic diagram of the circuit structure of another four-channel LED string display device provided in an embodiment of this application. The voltage adjustment circuit uses a buck converter as an example. Figure 11The synchronous rectification buck converter circuit shown also includes a second diode D6. When the voltage adjustment module has no output, the second transistor Q2 is off, and the current from the lamp string group flows back to the secondary winding 120 through the body diode of the third transistor Q3, the second inductor L2, and the fourth current-sharing diode D4. When the current is too high, it will cause significant heat loss in the body diode of the third transistor Q3. To reduce this loss, the second diode D6 is used to form a new current loop, allowing the current from the lamp string group to flow back to the secondary winding 120 through the second diode D6 and the fourth current-sharing diode D4. The second diode D6 is a low-power diode such as a Schottky diode.

[0110] This embodiment also provides a display control method applied to a display device, such as... Figure 7 As shown, it includes: a transformer, a voltage conversion module, a feedback module, and a string of lights; the transformer has a first-stage coil and a second-stage coil, which are coupled to the transformer's primary coil; the first-stage coil is used to output a first voltage based on the power received by the primary coil; the second-stage coil is used to alternately output a second voltage from its two ends based on the power received by the primary coil; the second-stage coil corresponds one-to-one with the string of lights; the voltage conversion module is used to generate a superimposed voltage based on the first voltage and superimpose the superimposed voltage onto the second voltage at the corresponding ends of the second-stage coil, and output the superimposed third voltage.

[0111] This embodiment provides a display control method including: receiving a feedback signal, which is generated by a feedback module based on the output current of the LED string group; adjusting a third voltage by adjusting a superimposed voltage based on the feedback signal; the third voltage being the operating voltage of the LED string group. In this embodiment, based on the feedback signal of the real-time current output of each LED string, the first voltage output by the first primary coil is adjusted to generate a superimposed voltage. This superimposed voltage is superimposed with the second voltage output by the second primary coil and transmitted to each LED string, so that each LED string operates at its rated current, preventing excessive current from flowing through the LED components in the LED string and causing damage to the components. The superimposed voltage is equivalent to a "variable voltage"; the second voltage is equivalent to a "fixed voltage." The superposition of these two voltages achieves stepped power supply, which helps reduce heat loss. Simultaneously, the two LED strings share the same power supply coil (i.e., the second primary coil) and voltage conversion module, which simplifies the circuit.

[0112] The display device and display control method provided in this embodiment include a transformer, a voltage conversion module, a feedback module, and a string of lights. Each voltage conversion module corresponds to a string of lights, which includes a first string and a second string of lights. The transformer has a primary coil and a secondary coil, coupled to the primary coil. The primary coil outputs a first voltage based on the power received from the primary coil. The secondary coil alternately outputs a second voltage from its two ends based on the power received from the primary coil. Each secondary coil corresponds to a string of lights. The voltage conversion module generates a superimposed voltage based on the first voltage and superimposes it onto the second voltage across the corresponding secondary coil, outputting a superimposed third voltage. The feedback module generates a feedback signal based on the output current of the string of lights and sends it to the voltage conversion module. The feedback signal instructs the voltage conversion module to adjust the third voltage. The first string of lights is connected to one end of the corresponding secondary coil, and the second string of lights is connected to the other end of the corresponding secondary coil, emitting light based on the third voltage. In this embodiment, the two strings of lights share the same power supply coil and voltage conversion module, simplifying the circuit. Simultaneously, the use of voltage superposition to achieve stepped power supply helps reduce heat loss.

[0113] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0114] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A display device, characterized in that, include: The system includes a transformer, a voltage conversion module, a feedback module, and a string of lights; wherein the voltage conversion module corresponds one-to-one with the string of lights, and the string of lights includes a first string of lights and a second string of lights. The first and second stage coils of the transformer are coupled to the primary coil of the transformer; the first stage coil is used to output a first voltage according to the power supply received by the primary coil. The second-stage coil is used to alternately output a second voltage from its two ends according to the power received by the primary coil; the second-stage coil corresponds one-to-one with the string of lights. The voltage conversion module is used to generate a superimposed voltage based on the first voltage and superimpose the superimposed voltage onto the second voltage across the corresponding secondary coil, and output the superimposed third voltage; The feedback module is used to generate a feedback signal based on the output current of the light string group and send it to the voltage conversion module. The feedback signal is used to instruct the voltage conversion module to adjust the third voltage. The first light string is connected to one end of the corresponding second-stage coil, and the second light string is connected to the other end of the corresponding second-stage coil, for emitting light based on the third voltage; The voltage conversion module includes a voltage adjustment module and a voltage superposition module; the voltage superposition module includes a second rectifier diode and a fourth rectifier diode. The positive terminal of the second rectifier diode is connected to the output terminal of the voltage adjustment module, and the positive terminal of the fourth rectifier diode is connected to the output terminal of the voltage adjustment module.

2. The display device according to claim 1, characterized in that, The voltage adjustment module is connected to the output terminal of the first primary coil and is used to generate a superimposed voltage based on the first voltage. The voltage superposition module receives the superposition voltage and is connected to both ends of the second-stage coil to superimpose the superposition voltage onto the second voltage at the corresponding ends of the second-stage coil, and outputs the superimposed third voltage. The feedback signal is used to instruct the voltage adjustment module to adjust the third voltage by adjusting the superimposed voltage.

3. The display device according to claim 2, wherein The voltage superposition module further includes a first current sharing capacitor, a first rectifier diode, and a third rectifier diode; One end of the first current-sharing capacitor is connected to one end of the second stage coil; the other end of the first current-sharing capacitor is connected to the anode of the first rectifier diode and the cathode of the second rectifier diode; the anode of the second rectifier diode is connected to the superimposed voltage; the cathode of the first rectifier diode is connected to the anode of the first lamp string; the cathode of the first lamp string is grounded. The positive terminal of the third rectifier diode is connected to the other end of the second stage coil and the negative terminal of the fourth rectifier diode, and the positive terminal of the fourth rectifier diode is connected to the superimposed voltage; the negative terminal of the third rectifier diode is connected to the positive terminal of the second lamp string; the negative terminal of the second lamp string is grounded.

4. The display device according to claim 2, wherein The voltage adjustment module includes: a second transistor, a third transistor, a second inductor, and a second capacitor; One end of the second transistor is connected to the output terminal of the first primary coil; the other end of the second transistor is connected to one end of the third transistor and one end of the second inductor; the other end of the third transistor is grounded. The other end of the second inductor serves as the output terminal of the voltage adjustment module, outputting the superimposed voltage; One end of the second capacitor is connected to the other end of the second inductor; the other end of the second capacitor is grounded. The control electrodes of the second transistor and the third transistor are both connected to the feedback module, which is used to adjust the switching frequency of the second transistor and the third transistor according to the feedback signal, so as to adjust the superimposed voltage.

5. The display device according to claim 4, wherein The voltage adjustment module also includes a second diode; The negative terminal of the second diode is connected to one end of the second capacitor; the positive terminal of the second diode is connected to the other end of the second capacitor.

6. The display device according to claim 1, wherein The display device further includes a first switching circuit and a first grounding resistor; The first switching circuit is located between the light string group and the first grounding resistor; One end of the first switching circuit is connected to the negative terminal of the first light string and the negative terminal of the second light string, and the other end of the first switching circuit is connected to one end of the first grounding resistor and the input terminal of the feedback module. The other end of the first grounding resistor is grounded; the first switching circuit is turned on or off based on the duty cycle control signal.

7. The display device according to claim 1, wherein The display device further includes: a second switching circuit and a second grounding resistor; The second switching circuit is located between the light string group and the second grounding resistor; One end of the second switching circuit is connected to the negative terminal of the first light string and the negative terminal of the second light string, and the other end of the second switching circuit is connected to one end of the second grounding resistor; the other end of the second grounding resistor is grounded. The second switching circuit is used to change the loop current to perform analog dimming.

8. The display device according to claim 7, wherein The second switching circuit includes: a fifth transistor and a comparator; One end of the fifth transistor is connected to the negative terminal of the first lamp string and the negative terminal of the second lamp string; the other end of the fifth transistor is connected to one end of the second grounding resistor and the inverting input terminal of the comparator. The comparator's non-inverting input terminal receives the required voltage of the lamp string group, and the comparator's output terminal is connected to the gate of the fifth transistor; Adjusting the resistance of the fifth transistor changes the circuit current, thus simulating dimming.

9. The display device according to claim 1, wherein The number of the secondary coil, the voltage conversion module, and the lamp string group are all multiple; The display device also includes multiple current-sharing inductors; The current-sharing inductors are coupled between two adjacent secondary coils.

10. A display control method applied to the display device according to any one of claims 1 to 9, characterized by, The method includes: Receive a feedback signal, which is generated by the feedback module based on the output current of the light string group; Based on the feedback signal, the superimposed voltage is adjusted to adjust the third voltage; the third voltage is the operating voltage of the light string group.

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