Display device

Abstract

The application provides a display device, comprising 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, the lamp string group comprises a first lamp string (140) and a second lamp string (150); a first secondary coil (110) of the transformer outputs a first voltage; two ends of a second secondary coil (120) of the transformer alternately output a second voltage; the second secondary coil (120) 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, so as to adjust the third voltage; the first lamp string (140) is connected to one end of the second secondary coil (120), the second lamp string (150) is connected to the other end of the second secondary coil (120), and the first lamp string (140) and the second lamp string (150) are used for emitting light based on the third voltage. In the application, two lamp strings share the same power supply coil and voltage conversion module, so that the circuit is simplified; meanwhile, step power supply is realized by using voltage superposition, and heat loss is reduced.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202210412214.4, filed on April 19, 2022, No. 202210415138.2, filed on April 20, 2022, and No. 202210421396.1, filed on April 21, 2022, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of display devices, and in particular to a display device. BACKGROUND

[0004] With the development of electronic technology, the integration of electronic devices including display devices such as televisions is becoming higher and higher, which puts forward higher and higher requirements on the power supply of the display device.

[0005] Taking a television as an example, since there are two power supply requirements of mainboard power supply and backlight driving of light emitting diode (LED) lamp string in the television, the system design is relatively complex. Specifically, in one related design, a resonant conversion circuit (LLC) module is used to output multiple direct current voltages based on alternating current to supply power to the mainboard and the lamp string. Among them, each lamp string corresponds to a direct current-direct current voltage adjustment module to adjust the fixed direct current voltage output by the LLC module to meet the voltage requirement of the lamp string. In another related design, two LLC modules are used to supply power to the mainboard and the lamp string. Among them, the output voltage of the secondary winding of the LLC module corresponding to the lamp string is adjusted by adjusting the alternating current voltage of the primary winding of the LLC module, so as to meet the voltage requirement of the lamp string. How to simplify the above power supply circuit becomes a problem to be solved. SUMMARY

[0006] The present application provides a display device to simplify the power supply circuit of the display device.

[0007] The application provides a display device, comprising 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, the lamp string group comprises a first lamp string and a second lamp string; a first secondary coil and a second secondary coil of the transformer are coupled with a primary coil of the transformer; the first secondary coil is used for outputting a first voltage according to a power supply received by the primary coil; the second secondary coil is used for alternately outputting a second voltage from two ends of the second secondary coil according to the power supply received by the primary coil; the second secondary coil corresponds to the lamp string group one by one; the voltage conversion module is used for generating a superimposed voltage according to the first voltage and superimposing the superimposed voltage to the second voltage at the two ends of the corresponding second secondary coil, and outputting a third voltage after superimposition; the feedback module is used for generating a feedback signal according to an output current of the lamp string group and sending the feedback signal to the voltage conversion module, and the feedback signal is used for instructing the voltage conversion module to adjust the third voltage; one end of the first lamp string is connected with the corresponding second secondary coil, and the other end of the second lamp string is connected with the corresponding second secondary coil, and is used for emitting light based on the third voltage. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A structural schematic diagram of a display device provided with an independent power board;

[0009] Figure 2 A schematic diagram of a connection relationship between a power board and a load of a display device;

[0010] Figure 3 A schematic diagram of a television power architecture;

[0011] Figure 4 A schematic diagram of a circuit structure for supplying power to a main board and an LED lamp string;

[0012] Figure 5 A schematic diagram of another circuit structure for supplying power to a main board and an LED lamp string;

[0013] Figure 6 A schematic diagram of still another circuit structure for supplying power to a main board and an LED lamp string;

[0014] Figure 7 A schematic diagram of a circuit structure of a two-way lamp string display device according to an embodiment of the application;

[0015] Figure 8 A schematic diagram of a circuit structure of a voltage conversion module according to an embodiment of the application;

[0016] Figure 9 A schematic diagram of a circuit structure of a voltage superimposition module according to an embodiment of the application;

[0017] Figure 10 A schematic diagram of a circuit structure of a voltage adjustment module according to an embodiment of the application;

[0018] Figure 11 A circuit structure schematic diagram of another voltage adjustment module according to an embodiment of the present application;

[0019] Figure 12 A circuit structure schematic diagram of a first switch circuit according to an embodiment of the present application;

[0020] Figure 13 A circuit structure schematic diagram of a second switch circuit according to an embodiment of the present application;

[0021] Figure 14 A circuit structure schematic diagram of a display device of a four-way light string according to an embodiment of the present application;

[0022] Figure 15 A circuit structure schematic diagram of another display device of a four-way light string according to an embodiment of the present application;

[0023] Figure 16 A circuit structure schematic diagram of still another display device of a four-way light string according to an embodiment of the present application;

[0024] Figure 17 A circuit structure schematic diagram of yet another display device of a four-way light string according to an embodiment of the present application;

[0025] Figure 18 A power supply circuit structure schematic diagram for supplying power to a mainboard and LED light string;

[0026] Figure 19 Another power supply circuit structure schematic diagram for supplying power to a mainboard and LED light string;

[0027] Figure 20 Still another power supply circuit structure schematic diagram for supplying power to a mainboard and LED light string;

[0028] Figure 21 A schematic diagram of an external adapter power supply mode according to an embodiment of the present application;

[0029] Figure 22 A power supply circuit structure schematic diagram of a display device according to an embodiment of the present application;

[0030] Figure 23 Another power supply circuit structure schematic diagram of a display device according to an embodiment of the present application;

[0031] Figure 24 A power supply circuit structure schematic diagram of a charge pump module according to an embodiment of the present application;

[0032] Figure 25A power supply circuit structure schematic diagram of a display device according to an embodiment of the present application;

[0033] Figure 26 A power supply circuit structure schematic diagram of a flyback isolation transformer module according to an embodiment of the present application;

[0034] Figure 27 A power supply circuit structure schematic diagram of a level conversion circuit according to an embodiment of the present application;

[0035] Figure 28 A power supply circuit structure schematic diagram of a level conversion circuit based on a charge pump module according to an embodiment of the present application;

[0036] Figure 29 A power supply circuit structure schematic diagram of a level conversion circuit based on a flyback isolation transformer module according to an embodiment of the present application;

[0037] Figure 30 A power supply circuit structure schematic diagram of a mainboard according to an embodiment of the present application;

[0038] Figure 31 A power supply circuit structure schematic diagram of a mainboard according to another embodiment of the present application;

[0039] Figure 32 A power supply circuit structure schematic diagram of a display device according to an embodiment of the present application;

[0040] Figure 33 A power supply circuit structure schematic diagram of a display device according to another embodiment of the present application;

[0041] Figure 34 A power supply circuit structure schematic diagram of a charge pump module according to an embodiment of the present application;

[0042] Figure 35 A power supply circuit structure schematic diagram of a charge pump module according to another embodiment of the present application;

[0043] Figure 36 A power supply circuit structure schematic diagram of a charge pump module according to another embodiment of the present application;

[0044] Figure 37 A power supply circuit structure schematic diagram of a charge pump module according to another embodiment of the present application;

[0045] Figure 38 A power supply circuit structure schematic diagram of a display device according to another embodiment of the present application;

[0046] Figure 39 A power supply circuit structure schematic diagram of a flyback isolation transformer module according to an embodiment of the present application;

[0047] Figure 40 Fig. 3 is a schematic diagram of another power supply circuit structure of a flyback isolation transformer module according to an embodiment of the present application;

[0048] Figure 41 Fig. 4 is a schematic diagram of a filter module according to an embodiment of the present application;

[0049] Figure 42 Fig. 5 is a schematic diagram of a filter module based on a charge pump module power supply circuit according to an embodiment of the present application;

[0050] Figure 43 Fig. 6 is a schematic diagram of a filter module based on a flyback isolation transformer module power supply circuit according to an embodiment of the present application;

[0051] Figure 44 Fig. 7 is a schematic diagram of a circuit structure for powering a main board according to an embodiment of the present application;

[0052] Figure 45 Fig. 8 is a schematic diagram of another circuit structure for powering a main board according to an embodiment of the present application. DETAILED DESCRIPTION

[0053] The embodiments will be described in detail below with reference to the drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following detailed description are not meant to be all-inclusive or all-exhaustive, but rather only a portion of all possible embodiments.

[0054] With the increasing demand for information, various types of display devices have emerged, such as computers, televisions, and projectors. A power supply circuit is one of the most important circuit structures in a display device, which can provide power for the display device so that the display device can operate normally. Some display devices are provided with a separate power board, and some display devices integrate the power board and the main board.

[0055] For example, the structure of a display device provided with a separate power board is described with reference to Fig. 1. Figure 1 Fig. 1 is a schematic diagram of a structure of a display device provided with a separate power board, which includes a power board 10 and a main board 20. Figure 1 Fig. 1 is a schematic diagram of a structure of a display device provided with a separate power board, which includes a power board 10 and a main board 20. Figure 1As shown, the display device includes a display panel 1, a backlight assembly 2, a mainboard 3, a power board 4, a rear housing 5, and a base 6. The display panel 1 is used to present images to the user; the backlight assembly 2 is located below the display panel 1 and is typically composed of optical components that provide sufficient brightness and evenly distributed light sources so that the display panel 1 can properly display images. The backlight assembly 2 also includes a backplate 20, on which the mainboard 3 and the power board 4 are disposed. These backplate 20 is typically stamped with convex structures, to which the mainboard 3 and the power board 4 are fixed by screws or hooks; the rear housing 5 is provided on the panel 1 to conceal components of the display device, such as the backlight assembly 2, the mainboard 3, and the power board 4, thereby enhancing the appearance; and the base 6 is used to support the display device.

[0056] In some embodiments, Figure 2 It is a schematic diagram showing the connection relationship between the power supply board and the load of the display device, such as Figure 2 As shown, the power board 4 includes an input terminal 41 and an output terminal 42 (a first output terminal 421, a second output terminal 422, and a third output terminal 423 are shown in the figure). The input terminal 41 is connected to the mains power, and the output terminal 42 is connected to the load. For example, the first output terminal 421 is connected to the LED light string used to light the display screen, the second output terminal 422 is connected to the speaker, and the third output terminal 423 is connected to the mainboard. The power board 4 needs to convert the AC mains power into the DC power required by the load, and this DC power usually has different specifications, for example, the speaker requires 18V, the panel requires 12V, etc.

[0057] In some embodiments, a power supply architecture of a display device is described using a television as an example. Figure 3 This is a schematic diagram of the TV power supply architecture. Figure 3 As shown, the power board may include: a rectifier bridge, a power factor correction (PFC) module and a resonant converter (LLC) module, wherein the LLC module includes a synchronous rectifier circuit ( Figure 3 The PFC module is connected to the LLC module, and the LLC module is connected to the load.

[0058] Among them, the rectifier bridge is used to rectify the input AC power and input the full-wave signal to the PFC module. An electromagnetic interference (EMI) filter can be connected before the AC power inputs the PFC module. Figure 3 (not shown) to perform high-frequency filtering on the input AC power.

[0059] The PFC module can include a PFC inductor, a switching power device, and a PFC control chip, and mainly performs power factor correction on the input AC power supply, and outputs a stable DC bus voltage (such as 380V) to the LLC module. The PFC module can effectively improve the power factor of the power supply and ensure that the voltage and current are in phase. Alternatively, in some embodiments, the PFC module can also not be provided in the power supply architecture as shown in Figure 3

[0060] The LLC module can adopt a double-MOS tube LLC resonant conversion circuit, and a synchronous rectification circuit is usually provided in the LLC module. The synchronous rectification circuit can mainly include a transformer, a controller, two MOS tubes, and a diode. In addition, the LLC module can also include a pulse frequency modulation (PFM) circuit, a capacitor, an inductor, and other components. The LLC module can specifically step down or step up the DC bus voltage input by the PFC module and output a constant voltage to the load. Usually, the LLC module can output multiple different voltages to meet the needs of different loads. Alternatively, in some other embodiments, the LLC module as shown in Figure 3

[0061] More specifically, still taking a television as an example, Figure 4 is a power supply circuit structure diagram for supplying power to a mainboard and LED lamp strings. The AC power (100V-240V, 50-60Hz) obtained by the power supply circuit is sequentially supplied to the mainboard, the multi-path LED lamp string, and other loads (not shown in Figure 4 ) through a filtering and rectifying module (rectifier bridge), a PFC module, and an LLC isolation voltage conversion module. Among them, the first secondary winding in the LLC isolation voltage conversion module provides a first voltage (for example, 12V) to the mainboard, the second secondary winding provides a second voltage (for example, 18V) to the mainboard, and the third secondary winding simultaneously provides a voltage to the multi-path LED lamp string.

[0062] Among them, the LED lamp string is used to light the display screen of the television, and the LED components in the LED lamp string need to work within a certain voltage drop range to reach their rated current. For example, in the case of a 16-path LED lamp string, each path of the LED lamp string includes 9 LED components, and under the condition of 120mA, the voltage range required by the multi-path LED lamp string is 51.3V-58.5V, and the total current is 1.92A.

[0063] ​​Since the working voltage of the LED light string is affected by the working environment, the hardware characteristics and the service life of the LED component, it needs to be adjusted in real time. Therefore, a voltage adjustment module (buck step-down circuit or boost step-up circuit or buck-boost step-up and step-down circuit) is also provided in the power supply circuit. The working voltage or working current of the LED light string can be detected, and a feedback signal is sent to the voltage adjustment module according to the change of the working voltage or working current, so that the voltage adjustment module can adjust the voltage output to the LED light string according to the feedback signal, thereby maintaining the stability of the working current of the LED light string.

[0064] As shown in Figure 4 , taking the power supply for the main board and two LED light strings as an example, a voltage adjustment module in the form of a boost step-up circuit is configured for each LED light string. The voltage adjustment module can adjust the fixed voltage output by the third auxiliary winding and transmit it to each LED light string after adjustment, so that each LED light string works at the rated current, preventing excessive current from flowing through the LED components in the LED light string and causing damage to the components.

[0065] However, in the power supply circuit as shown in Figure 4 , one voltage adjustment module is provided in the power supply circuit for each LED light string. That is, with each additional LED light string, a corresponding voltage adjustment module needs to be added. Therefore, the circuit structure is relatively complex, which in turn occupies a larger area of the PCB board where the power supply circuit is located, ultimately increasing the cost of the power supply circuit.

[0066] In some embodiments, Figure 5 is another circuit structure diagram for supplying power to the main board and the LED light string. The AC power (100V-240V, 50-60Hz) obtained by the power supply circuit passes through the filtering and rectifying module (rectifier bridge), PFC module and LLC isolation voltage conversion module in turn, and supplies power to the main board, multiple LED light strings and other loads (not shown in Figure 5 ). Among them, the first auxiliary winding in the LLC isolation voltage conversion module 1 provides a first voltage (for example, 12V) to the main board, and the second auxiliary winding provides a second voltage (for example, 18V) to the main board; the LLC isolation voltage conversion module 2 provides voltage to two LED light strings at the same time. The LLC isolation voltage conversion module 2 uses the characteristics of AC power to alternately provide working voltage to the two LED light strings. The controller of the LLC isolation voltage conversion module 2 receives the current feedback of the two LED light strings, and then adjusts the voltage output by the LLC isolation voltage conversion module 2, and transmits the adjusted voltage to the two LED light strings, so that each LED light string works at the rated current, preventing excessive current from flowing through the LED components in the LED light string and causing damage to the components.

[0067] The capacitor connected to one output end of the secondary winding of the LLC isolated voltage conversion module 2 plays a role of current sharing, for making the working currents of the two LED light strings equal; the two diodes in series between the two output ends of the secondary winding and the LED light strings play a role of rectification based on the unidirectional conduction characteristic; and the grounding diode connected to the two output ends of the secondary winding plays a role of voltage stabilization.

[0068] However, in the power supply circuit shown in Figure 5 The output voltage range of the LLC isolated voltage conversion module 2 is limited, and when the current size needs to be changed, the output range of the LLC isolated voltage conversion module 2 is greatly limited. In addition, the display device can have more than two LED light strings, and according to the power supply circuit shown in Figure 5 With the increase of each two LED light strings, one secondary winding of the LLC isolated voltage conversion module 2 needs to be added to supply power to the newly added LED light string. A large number of secondary windings will lead to relatively difficult transformer design, and the cost of complex circuit is also high.

[0069] In some embodiments, Figure 6 For another circuit structure schematic diagram for supplying power to the main board and the LED light strings. The AC power (100V-240V, 50-60Hz) obtained by the power supply circuit passes through the filter rectification module (rectifier bridge), PFC module and LLC isolated voltage conversion module in sequence, and supplies power to the main board, multiple LED light strings and other loads (not shown in Figure 6 The LLC isolated voltage conversion module includes four secondary windings, the first secondary winding provides a first voltage (for example, 12V) to the main board, and the second secondary winding provides a second voltage (for example, 18V) to the main board; the second secondary winding and the third secondary winding jointly supply power to the second LED light string; and the second secondary winding and the fourth secondary winding jointly supply power to the first LED light string.

[0070] Specifically, the 18V voltage output by the second secondary winding passes through 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, and the superimposed voltage supplies power to the second LED light string.

[0071] Similarly, the 18V voltage output by the second secondary winding passes through 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, and the superimposed voltage supplies power to the first LED light string.

[0072] In Figure 6The power supply circuit shown in the figure is a "step power supply" in which the "variable voltage" and the "fixed voltage" are superimposed, which is beneficial to reduce the voltage requirement of the switch tube, capacitor and other elements in the voltage adjustment module, thereby reducing the cost. However, with each additional LED light string, a corresponding secondary winding needs to be added to the LLC isolated voltage conversion module, and a corresponding voltage adjustment module needs to be added. A large number of secondary windings will make the transformer design relatively difficult; at the same time, the circuit structure is relatively complex, thereby occupying a larger area of the PCB board where the power supply circuit is located, ultimately increasing the cost of the power supply circuit.

[0073] Based on this, the display device provided by the present application shares one secondary coil and voltage conversion module for two LED light strings, wherein the two ends of the secondary coil alternately output "fixed voltage", and the "variable voltage" output by the voltage conversion module is superimposed to realize "step power supply" for the two LED light strings. It can not only simplify the power supply circuit, but also reduce the heat loss.

[0074] The content of the present application and how the content of the present application solves the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0075] Figure 7 The circuit structure of a two-way light string display device according to an embodiment of the present application is shown in the figure. As shown in the figure, it includes a transformer, a voltage conversion module, a feedback module and a light string group; wherein the voltage conversion module corresponds to the light string group one by one, and the light string group includes a first light string 140 and a second light string 150; Figure 7

[0076] Figure 7 In the transformer, the LLC isolated voltage conversion module is taken as an example. The first secondary coil 110 and the second secondary coil 120 of the LLC isolated voltage conversion module are coupled with the primary coil 100 of the LLC isolated voltage conversion module; the first secondary coil 110 is used to output a first voltage according to the power received by the primary coil 100; the second secondary coil 120 is used to alternately output a second voltage from the two ends of the second secondary coil 120 according to the power received by the primary coil 100; the second secondary coil 120 corresponds to the light string group one by one; the voltage conversion module is used to generate a superimposed voltage according to the first voltage and superimpose the superimposed voltage to the second voltage at the two ends of the corresponding second secondary coil, and output a third voltage after superposition;

[0077] ​The feedback module is configured to generate a feedback signal according to an output current of the lamp string group and send the feedback signal to the voltage conversion module, and the feedback signal is used to instruct the voltage conversion module to adjust the third voltage.

[0078] In the embodiment, the first secondary coil 110 is coupled with the primary coil 100 to generate alternating current, and the first secondary coil 110 is used to output a first voltage. Figure 7 The power supply circuit shown in the embodiment further includes a filter rectifier module (rectifier bridge) and a PFC module, which are used to process the acquired AC power supply and supply power to a mainboard, multiple LED lamp strings and other loads (not shown in the figure) of the display device via the LLC isolation voltage conversion module. Figure 7 In the embodiment, the first secondary coil 110 is coupled with the primary coil 100 to generate alternating current, and the first secondary coil 110 is used to output a first voltage.

[0079] In the embodiment, the first secondary coil 110 is coupled with the primary coil 100 to generate alternating current, and the first secondary coil 110 is used to output a first voltage. Figure 7 In the embodiment, the first voltage is taken as an example of 18V DC voltage. Because the first secondary coil 110 is coupled with the primary coil 100 to generate alternating current, the alternating current needs to be converted into direct current through the above-mentioned rectifier circuit.

[0080] In the embodiment, the second secondary coil 120 is coupled with the primary coil 100 to generate alternating current, and the two ends of the second secondary coil are used to alternately output a second voltage, which is equivalent to a "fixed voltage". The voltage conversion module is used to adjust the first voltage output by the first secondary coil to generate a superimposed voltage according to the feedback signal, and the superimposed voltage is equivalent to a "variable voltage". The voltage conversion module is used to superimpose the superimposed voltage on the second voltage to output a third voltage. In the embodiment, the two lamp strings share the same power supply coil and voltage conversion module, so that the circuit is simplified. Meanwhile, the voltage superposition of the "fixed voltage" and the "variable voltage" is used to realize step power supply, which is conducive to reducing heat loss.

[0081] In the embodiment, the feedback module can be in a current feedback mode or a voltage feedback mode. The feedback module can generate a feedback signal according to the current of a single lamp string or the current of multiple lamp strings. When the feedback is performed by the single lamp string, the reference current value set in the feedback module is the required working current of the single lamp string. When the feedback is performed by the two lamp strings, the reference current value set in the feedback module is twice the required working current of the single lamp string. The reference current value is used to compare with the actual current. If the actual current is higher than the reference current value, the feedback signal output by the feedback module instructs the voltage adjustment module to reduce the third voltage. If the actual current is equal to the reference current value, the feedback signal output by the feedback module instructs the voltage adjustment module to maintain the third voltage. If the actual current is lower than the reference current value, the feedback signal output by the feedback module instructs the voltage adjustment module to increase the third voltage.

[0082] Figure 7 The two light strings jointly feedback. Specifically, the feedback module generates a feedback signal according to the total current of the first light string 140 and the second light string 150 in the light string group, and sends the feedback signal to the voltage conversion module, so as to instruct the voltage conversion module to adjust the third voltage. The first light string 140 and the second light string 150 can be directly grounded, or grounded through a grounding circuit Rn. The grounding circuit Rn is beneficial to release static electricity and avoid static electricity accumulation.

[0083] In some embodiments, Figure 8 A circuit structure schematic diagram of a voltage conversion module according to an embodiment of the present application. The voltage conversion module includes: a voltage adjustment module and a voltage superposition module; the voltage adjustment module is connected with the output end of the first secondary coil, and is used to generate a superposition voltage according to a first voltage; the voltage superposition module receives the superposition voltage and is connected with both ends of the second secondary coil, and is used to superimpose the superposition voltage on a second voltage corresponding to both ends of the second secondary coil, and output a third voltage after superposition; wherein the feedback signal is used to instruct the voltage adjustment module to adjust the third voltage by adjusting the superposition voltage.

[0084] The second voltage corresponds to a "fixed voltage"; the voltage adjustment module adjusts the first voltage according to the feedback signal to output a superposition voltage, which corresponds to a "variable voltage". The voltage superposition module superimposes the superposition voltage on the second voltage to output a third voltage after superposition, which is used to supply power to the light string group. The step-by-step power supply mode is adopted, which is beneficial to reduce heat loss.

[0085] 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.

[0086] One end of the first current-sharing capacitor C1 is connected with one end of the second secondary coil; the other end of the first current-sharing capacitor C1 is connected with the anode of the first rectifier diode D1 and the cathode of the second rectifier diode D2; the anode of the second rectifier diode D2 is connected with the superposition voltage; the cathode of the first rectifier diode D1 is connected with the anode of the first light string 140; and the cathode of the first light string 140 is grounded.

[0087] The anode of the third rectifier diode D3 is connected with the other end of the second secondary coil 120 and the cathode of the fourth rectifier diode D4, and the anode of the fourth rectifier diode D4 is connected with the superposition voltage; the cathode of the third rectifier diode D3 is connected with the anode of the second light string 150; and the cathode of the second light string 150 is grounded.

[0088] Figure 9Fig. 1 is a schematic diagram of a circuit structure of a voltage superposition module according to an embodiment of the present application. When the primary coil 100 is turned on and off under the internal control of the LLC isolation voltage conversion module, the first current-sharing capacitor C1 performs charging and discharging processes, respectively.

[0089] When the first current-sharing capacitor C1 discharges, current flows from the first end (i.e., the left end of the first current-sharing capacitor C1 as shown in Fig. 1) to the second end (i.e., the right end of the first current-sharing capacitor C1 as shown in Fig. 1) of the first current-sharing capacitor C1, and the electric quantity in the first current-sharing capacitor C1 is released through the loop of the first lamp string 140. At the same time, the superposition voltage output by the voltage adjustment module is input to the anode of the first rectifier diode D1 through the second rectifier diode D2, current superposition occurs at the anode of the first rectifier diode D1, and the current is input to the first lamp string 140 from the cathode of the first rectifier diode D1. Figure 10 Figure 10 When the first current-sharing capacitor C1 discharges, current flows from the first end (i.e., the left end of the first current-sharing capacitor C1 as shown in Fig. 1) to the second end (i.e., the right end of the first current-sharing capacitor C1 as shown in Fig. 1) of the first current-sharing capacitor C1, and the electric quantity in the first current-sharing capacitor C1 is released through the loop of the first lamp string 140. At the same time, the superposition voltage output by the voltage adjustment module is input to the anode of the first rectifier diode D1 through the second rectifier diode D2, current superposition occurs at the anode of the first rectifier diode D1, and the current is input to the first lamp string 140 from the cathode of the first rectifier diode D1.

[0090] When the first current-sharing capacitor C1 discharges, current flows from the first end (i.e., the left end of the first current-sharing capacitor C1 as shown in Fig. 1) to the second end (i.e., the right end of the first current-sharing capacitor C1 as shown in Fig. 1) of the first current-sharing capacitor C1, and the electric quantity in the first current-sharing capacitor C1 is released through the loop of the first lamp string 140. At the same time, the superposition voltage output by the voltage adjustment module is input to the anode of the first rectifier diode D1 through the second rectifier diode D2, current superposition occurs at the anode of the first rectifier diode D1, and the current is input to the first lamp string 140 from the cathode of the first rectifier diode D1.

[0091] Because the total number of charges is equal during the charging and discharging processes of the current-sharing capacitor, the charges flowing through the two lamp strings are equal, and thus the currents of the two lamp strings are equal, thereby achieving current sharing of the two lamp strings. If the currents of the two lamp strings are not equal, a voltage difference will be generated on the first current-sharing capacitor C1, so that the loop voltage drops of the first lamp string 140 and the second lamp string 150 are the same, that is, the impedance is balanced. After a plurality of periods, the currents reach an equal balance state. Therefore, in a long process, the currents of the two LED lamp strings are equal.

[0092] The loop in which the first lamp string 140 is located includes the first rectifier diode D1, the first lamp string 140, the feedback module, the voltage adjustment module, the fourth rectifier diode D4, and the second secondary winding 120. The loop in which the second lamp string 150 is located includes the second secondary winding 120, the third rectifier diode D3, the second lamp string 150, the feedback module, the voltage adjustment module, and the second rectifier diode D2.

[0093] In the embodiment of the present application, the two lamp strings share the same power supply coil (i.e., the second secondary winding 120) and the voltage adjustment module, which simplifies the circuit. At the same time, voltage superposition is achieved by using two rectifier diodes, which realizes step-by-step power supply for each lamp string and is conducive to reducing heat loss.

[0094] ​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 end of the first secondary coil 110; the other end of the first inductor L1 is connected to one end of the first transistor Q1 and the positive electrode of the first diode D5; the other end of the first transistor Q1 is grounded; the negative electrode of the first diode D5 serves as the output end of the voltage adjustment module and outputs the superimposed voltage; one end of the first capacitor C2 is connected to the negative electrode 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, which is used to adjust the switching frequency of the first transistor Q1 according to the feedback signal to adjust the superimposed voltage.

[0095] Figure 10 FIG. 1 is a schematic diagram of a circuit structure of a voltage adjustment module according to an embodiment of the present application. When the first transistor Q1 is turned on, the output end of the first secondary coil 110 continuously outputs the first voltage to charge the first inductor L1, so that the current of the first inductor L1 linearly increases.

[0096] When the first transistor Q1 is turned off, the first inductor L1 can only discharge through the first diode D5, and outputs the superimposed voltage from the negative electrode of the first diode D5 to the second rectifier diode D2 and the fourth rectifier diode D4, while charging the first capacitor C2; the voltage across the capacitor rises and is higher than the input first voltage.

[0097] When the first transistor Q1 is turned on again, the first inductor L1 is charged again; at the same time, due to the one-way conductivity of the first diode D5, the first capacitor C2 discharges and outputs the superimposed voltage to the second rectifier diode D2 and the fourth rectifier diode D4.

[0098] By controlling the switching frequency of the first transistor Q1 or selecting a first capacitor C2 with a larger capacity, a superimposed voltage can be continuously outputted, and the 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 for discharging static electricity and improving safety.

[0099] In some embodiments, Figure 10 The current feedback mode is adopted. The feedback module includes a first driving chip, which is used to collect the actual total current of the first light string 140 and the second light string 150 in real time, generate a feedback signal, and enable the voltage adjustment module to timely and effectively adjust the voltage to prevent excessive current from flowing through the LED components in the first light string 140 and the second light string 150 to cause damage to the components.

[0100] In some embodiments, the voltage adjustment module can be a buck step-down 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 end of the first secondary 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 end of the voltage adjustment module, outputting the 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 electrode of the second transistor Q2 and the control electrode of the third transistor Q3 are both connected to the feedback module, which is used to adjust the switching frequency of the second transistor Q2 and the third transistor Q3 according to the feedback signal to adjust the superimposed voltage.

[0101] Figure 11 Figure 2 is a schematic diagram of the circuit structure of another voltage adjustment module according to an embodiment of the present application. This voltage adjustment module is a synchronous rectifier buck circuit. The third transistor Q3 is used instead of the rectifier diode, which helps improve the voltage conversion efficiency.

[0102] When the second transistor Q2 is turned on and the third transistor Q3 is turned off, the output terminal of the first secondary winding 110 continuously outputs the first voltage, charging the second inductor L2, causing the current in 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, and the third capacitor C3 is charged. When the second transistor Q2 is turned off and the third transistor Q3 is turned on, the second inductor L2 is discharged through the third transistor Q3, causing the current in the second inductor L2 to decrease linearly. At this time, a superimposed voltage is output to the second rectifier diode D2 and the fourth rectifier diode D4 through the third capacitor C3 and the gradually decreasing second inductor L2.

[0103] By controlling the switching frequency 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.

[0104] In some embodiments, when using Figure 11 In the synchronous rectification buck step-down circuit shown, the voltage adjustment module further includes a second diode D6; the cathode of the second diode D6 is connected to one end of the third capacitor C3; and the anode of the second diode D6 is connected to the other end of the third capacitor C3.

[0105] When the voltage adjustment module has no output, the second transistor Q2 is turned off, and the current of the light string group flows back to the second secondary coil 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, a new current loop is formed using the second diode D6, so that the current of the light string group flows back to the second secondary coil 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.

[0106] The aforementioned buck topology and boost topology can be selected according to project needs. For example, the buck topology has the advantage of low cost, but the output voltage range is narrow; while the boost topology has the advantage of a wide output voltage range, but its cost is relatively high.

[0107] The display device in some embodiments further includes a first switching circuit and a first grounding resistor R3; the first switching circuit is located between the light string group and the first grounding resistor R3; one end of the first switching circuit is connected to the negative pole of the first light string and the negative pole of the second light string, and the other end of the first switching circuit is connected to one end of the first grounding resistor R3 and the input end 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.

[0108] Figure 12 FIG. 1 is a schematic diagram of a circuit structure of a first switch circuit according to an embodiment of the present application. Figure 12 As shown, for a multi-output circuit, the voltages of multiple secondary coils may have cross-regulation issues. Cross-regulation refers to the impact on the output voltage of a certain circuit when other circuits are loaded. For example, when the output voltage of the third secondary coil 130 is heavily loaded, the output voltages of the first secondary coil 110 and the second secondary coil 120 will be increased. As a result, when the voltage conversion module is not working, the second voltage output by the second secondary coil 120 exceeds the operating voltage of the light string group, which will cause the light string group to light up naturally. In other words, the lighting and shutoff of the light string group are uncontrolled.

[0109] Therefore, it is necessary to add a first switch circuit in the circuit of the light string group to ensure that the light string group is in the off state when the light string group 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 the off state. Among them, the duty cycle control signal (i.e. Figure 12 The PWM control signal shown) can be synchronized with the control signal of the display device state, that is, when the display device is controlled to be in the standby state, the light string group is synchronously controlled by the duty cycle control signal to be in the non-luminous state.

[0110] In some embodiments, the first switch circuit comprises: a fourth transistor Q4; one end of the fourth transistor Q4 is connected with the negative pole of the first lamp string 140 and the negative pole of the second lamp string 150; the other end of the fourth transistor Q4 is connected with one end of the first grounding resistor R3 and the input end of the feedback module; the gate of the fourth transistor Q4 is connected with the duty cycle control signal, and the fourth transistor is turned on or turned off based on the duty cycle control signal. Referring to Figure 12 When the PWM control signal is low, the fourth transistor Q4 is turned off, so the lamp string group is not lit.

[0111] In some embodiments of the display device, the display device further comprises: a second switch circuit and a second grounding resistor R4; the second switch circuit is located between the lamp string group and the second grounding resistor R4; one end of the second switch circuit is connected with the negative pole of the first lamp string 140 and the negative pole of the second lamp string 150, and the other end of the second switch circuit is connected with one end of the second grounding resistor R4; the other end of the second grounding resistor R4 is grounded; the second switch circuit is used to change the loop current to simulate dimming.

[0112] Figure 13 The circuit structure diagram of a second switch circuit according to an embodiment of the present application is shown. The simulation dimming is achieved by changing the current in the lamp string group loop to change the brightness of the lamp string group. For the requirement of simulation dimming, if the lamp string group current is small, the required working voltage of the lamp string group is smaller, and then the second voltage output by the second secondary coil 120 is more likely to exceed the required working voltage of the lamp string group. When the second voltage output by the second secondary coil 120 is unchanged, by adjusting the resistance value in the loop through the second switch circuit, the current in the loop is changed. Compared with the method of adjusting the second voltage output by the second secondary coil 120 to achieve dimming, the circuit design is simpler.

[0113] In some embodiments, the second switch circuit comprises: a fifth transistor Q5 and a comparator; one end of the fifth transistor Q5 is connected with the negative pole of the first lamp string 140 and the negative pole of the second lamp string 150; the other end of the fifth transistor Q5 is connected with one end of the second grounding resistor R4 and the inverting input end of the comparator; the non-inverting input end of the comparator inputs the required voltage of the lamp string group, and the output end of the comparator is connected with the gate of the fifth transistor Q5; the resistance value of the fifth transistor Q5 is adjusted to change the loop current to simulate dimming.

[0114] Referring to Figure 13The inverting input end of the comparator receives the actual total current of the first light string 140 and the second light 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 the voltage feedback signal refers to the related art. The non-inverting input end of the comparator inputs a reference voltage, which is converted based on a reference current. The scheme for converting the reference current signal into the reference voltage signal refers to the related art. When the voltage feedback signal exceeds the reference voltage, the fifth transistor Q5 can be set in a linear working state to absorb the excess voltage on the fifth transistor Q5.

[0115] wherein, Figure 13 The voltage feedback mode is adopted. One end of the first feedback resistor R5 is connected with the negative electrode of the first light string 140 and the negative electrode of the second light string 150, and the other end of the first feedback resistor R5 is connected with one end of the second feedback resistor R6. The other end of the second feedback resistor R6 is grounded. The second driving chip samples the connection point of the first feedback resistor R5 and the second feedback resistor R6 and sends a voltage feedback signal to the voltage conversion module.

[0116] The second driving chip is used to collect the voltage signal of 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 timely and effectively adjust the voltage, thereby preventing the damage of components caused by the excessive current flowing through the LED components in the first light string 140 and the second light string 150.

[0117] Referring to Figure 7 to Figure 13 The display device provided in the embodiment further includes a mainboard. The transformer further includes a third secondary coil 130 coupled with the primary coil. The third secondary coil 130 is configured to output a fourth voltage based on the power received by the primary coil. The first voltage output by the first secondary coil 110 and the fourth voltage output by the third secondary coil 130 are both used to power the mainboard. For example, the first voltage is 18V, and the fourth voltage is 12V.

[0118] In some embodiments of the display device, the number of the second secondary coils 120, the voltage conversion module, and the light string groups are all multiple. The display device further includes multiple current-sharing inductors. The current-sharing inductors are arranged between two adjacent second secondary coils and are coupled with each other.

[0119] Taking a four-way light string as an example, Figure 14 FIG. 1 is a circuit structure schematic diagram of a display device according to a four-way light string of an embodiment of the present application. The voltage adjustment module takes a boost circuit as an example. As shown in FIG. 1, the display device includes a transformer 100, a first driving chip 200, a second driving chip 300, a voltage conversion module 400, and a light string group 500. Figure 14As shown, including two groups of light string groups, four-way light string: the first light string 140, the second light string 150, the third light string 160, the fourth light string 170; two second secondary coils 120 and 121, corresponding to two groups of light string groups. Among them, two second secondary coils 120 and 121 are provided with mutual coupling current-sharing inductors: third inductor L3 and fourth inductor L4.

[0120] When the winding direction, the number of turns, etc. of the two second secondary coils 120 and 121 are the same, during power supply, the current direction in the power supply circuit of the second light string 150 and the power supply circuit of the third light string 160 is opposite, so impedance will be generated. The third inductor L3 is connected in series in the power supply circuit of the second light string 150, and the fourth inductor L4 is connected in series in the power supply circuit of the third light string 160. The third inductor L3 and the fourth inductor L4 are mutually coupled and used to balance the generated impedance.

[0121] Among them, the feedback module adopts four-way light string common feedback, so the reference current value set in the feedback module is 4 times the demand working current of a light string. In addition, the principle of the newly added second secondary coil 121 for supplying power to the third light string 160 and the fourth light string 170 will not be repeated.

[0122] Figure 15 The circuit structure schematic diagram of another four-way light string display device according to the embodiment of the present application. For the power supply circuit of the four-way light string display device, the same as the above-mentioned embodiment, the first switch circuit is located between the four-way light string (the first light string 140, the second light string 150, the third light string 160 and the fourth light string 170) and the ground resistance R3. Figure 12 The same as the above-mentioned embodiment, the first switch circuit is located between the four-way light string (the first light string 140, the second light string 150, the third light string 160 and the fourth light string 170) and the ground resistance R3. For the multi-output circuit, the voltage of the multiple secondary coils may have a cross-regulation problem. In order to avoid that the second voltage output by the second secondary coil 120 or 121 exceeds the working voltage of the light string group when the voltage conversion module does not work, causing the light string group to be lit, the first switch circuit is added in the loop of the light string group, to ensure that the light string group is in the off state when the light string group does not need to emit light. Specifically, the first switch circuit includes a fourth transistor Q4, when the PWM control signal is low, the fourth transistor Q4 is cut off, so the light string group does not light.

[0123] Figure 16Fig. 4 is a schematic diagram of a circuit structure of a display device of another four-way light string according to an embodiment of the present application. In the power supply circuit of the display device of the four-way light string, the second switch circuit is located between the light string group and the grounding resistor. By the second switch circuit, the resistance value in the loop is adjusted, the current in the loop is changed, and then the brightness of the light string group is adjusted. Specifically, when the actual voltage of the light string group exceeds the reference voltage, the transistor can be set in a linear working state to share the excess voltage, so as to avoid the voltage division of the light string group being too large and causing damage to the circuit. Specifically, the second switch circuit includes a fifth transistor Q5 and a comparator. The inverting input terminal of the comparator receives the actual total current of the first light string 140 and the second light 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 the voltage feedback signal is referred to related technologies. The non-inverting input terminal of the comparator inputs a reference voltage, which is converted from a reference current. The scheme for converting the reference current signal into the reference voltage signal is referred to related technologies. When the voltage feedback signal exceeds the reference voltage, the fifth transistor Q5 can be set in a linear working state to absorb the excess voltage on the fifth transistor Q5.

[0124] Figure 17 Fig. 5 is a schematic diagram of a circuit structure of a display device of another four-way light string according to an embodiment of the present application. The voltage adjustment circuit takes a buck voltage reduction circuit as an example, adopts the synchronous rectification buck voltage reduction circuit shown in Fig. 5, and is provided with a second diode D6. Figure 11 When the voltage adjustment module has no output, the second transistor Q2 is cut off, and the current of the light string group flows back to the second secondary coil 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, a large amount of heat loss will be caused on the body diode of the third transistor Q3. In order to reduce the loss, the second diode D6 is used to form a new current loop, so that the current of the light string group flows back to the second secondary coil 120 through the second diode D6 and the fourth current sharing diode D4. The second diode D6 adopts a Schottky diode or other low-power diode.

[0125] The embodiment also provides a display control method applied to a display device. The display device includes a transformer, a voltage conversion module, a feedback module and a light string group, as shown in Fig. 6. The first secondary coil and the second secondary coil of the transformer are coupled with the primary coil of the transformer. The first secondary coil is configured to output a first voltage according to the power received by the primary coil. The second secondary coil is configured to alternately output a second voltage from two ends of the second secondary coil according to the power received by the primary coil. The second secondary coil corresponds to the light string group one by one. The voltage conversion module is configured to generate a superimposed voltage according to the first voltage and superimpose the superimposed voltage to the second voltage at the two ends of the corresponding second secondary coil to output a third voltage after superimposition. Figure 7 The embodiment also provides a display control method applied to a display device. The display device includes a transformer, a voltage conversion module, a feedback module and a light string group, as shown in Fig. 6. The first secondary coil and the second secondary coil of the transformer are coupled with the primary coil of the transformer. The first secondary coil is configured to output a first voltage according to the power received by the primary coil. The second secondary coil is configured to alternately output a second voltage from two ends of the second secondary coil according to the power received by the primary coil. The second secondary coil corresponds to the light string group one by one. The voltage conversion module is configured to generate a superimposed voltage according to the first voltage and superimpose the superimposed voltage to the second voltage at the two ends of the corresponding second secondary coil to output a third voltage after superimposition.

[0126] The display control method provided in the embodiment comprises: receiving a feedback signal, the feedback signal being generated by a feedback module according to an output current of the lamp string group; adjusting a third voltage by adjusting a superimposed voltage based on the feedback signal; and the third voltage being a working voltage of the lamp string group. In the embodiment, the first voltage output by the first secondary coil is adjusted according to the feedback signal of the real-time current output by each LED lamp string to generate a superimposed voltage, the superimposed voltage is superimposed with a second voltage output by the second secondary coil and then transmitted to each LED lamp string, so that each LED lamp string works at a rated current, and damage to components caused by excessive current flowing through the LED components in the LED lamp string is prevented. The superimposed voltage is equivalent to a "variable voltage", and the second voltage is equivalent to a "fixed voltage", and the voltage superposition realizes step-by-step power supply, which is conducive to reducing heat loss; meanwhile, the two lamp strings share the same power supply coil (i.e. the second secondary coil) and voltage conversion module, which is conducive to simplifying the circuit.

[0127] The display device provided in the embodiment 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; the first secondary coil and the second secondary coil of the transformer are coupled with the primary coil of the transformer; the first secondary coil is configured to output a first voltage according to the power received by the primary coil; the second secondary coil is configured to alternately output a second voltage from two ends of the second secondary coil according to the power received by the primary coil; the second secondary coil corresponds to the lamp string group one by one; the voltage conversion module is configured to generate a superimposed voltage according to the first voltage and superimpose the superimposed voltage to the second voltage at the two ends of the corresponding second secondary coil to output a third voltage after superimposition; the feedback module is configured to generate a feedback signal according to the output current of the lamp string group and send the feedback signal to the voltage conversion module, the feedback signal being used to instruct the voltage conversion module to adjust the third voltage; one end of the first lamp string is connected to the corresponding second secondary coil, and the other end of the second lamp string is connected to the corresponding second secondary coil, and the first lamp string and the second lamp string are configured to emit light based on the third voltage. The two lamp strings in the embodiment share the same power supply coil and voltage conversion module, which simplifies the circuit; meanwhile, voltage superposition is used to realize step-by-step power supply, which is conducive to reducing heat loss.

[0128] In order to meet the power supply demand of the load in the display device by using the direct-current voltage output by the external adapter, the present application further provides the following embodiments.

[0129] Similarly, taking a television as an example, Figure 18 is a power supply circuit structure diagram for supplying power to the mainboard and the LED lamp string. The alternating current (100V-240V, 50-60Hz) obtained by the power supply circuit is sequentially transmitted to the mainboard, the multiple LED lamp strings and other loads of the display device after passing through the filtering and rectifying module (rectifier bridge), the PFC module and the LLC isolation voltage conversion moduleFigure 18 The first secondary winding in the LLC isolated voltage conversion module provides a fifth voltage (e.g. 12V) to the main board, the second secondary winding provides a sixth voltage (e.g. 18V) to the main board, and the third secondary winding provides voltage to the multi-channel LED lamp string.

[0130] The multi-channel LED lamp string is used to light the display screen of the TV set, and the LED components in the multi-channel LED lamp string need to work within a certain voltage drop range to achieve the rated current of the LED components. For example, in the case of a 16-channel LED lamp string, each channel including 9 LED components, under the condition of 120mA, the working voltage range required by the multi-channel LED lamp string is 51.3V-58.5V, and the total current is 1.92A.

[0131] Since the voltage range required by the multi-channel LED lamp string is related to the working environment of the multi-channel LED lamp string, the hardware characteristics of the LED components, the service life, etc., it needs to be adjusted in real time. Therefore, the secondary winding in the LLC isolated voltage conversion module for powering the multi-channel LED lamp string is additionally connected to a voltage adjustment module (such as a buck circuit or a boost circuit, for example, a boost circuit in Figure 18 The voltage adjustment module can adjust the voltage directly output by the third secondary winding according to the real-time current feedback result of the multi-channel LED lamp string, so that the multi-channel LED driving module controls the multi-channel LED lamp string to work at the rated current according to the received adjusted voltage, preventing excessive current from flowing through the LED components in the multi-channel LED lamp string and causing damage to the components.

[0132] However, in the power supply circuit as shown in Figure 18 The voltage stress of the voltage adjustment module provided for the multi-channel LED lamp string in the power supply circuit is large. For example, when the voltage range required by the multi-channel LED lamp string is 51.3V-58.5V, the voltage adjustment module needs to adjust the voltage greater than 50V by boosting or bucking, resulting in high voltage withstand value of the components such as the switch tube and the capacitor in the voltage adjustment module, and thus occupying a larger area of the PCB board where the power supply circuit is located, ultimately increasing the cost of the power supply circuit.

[0133] Figure 19 Another power supply circuit structure for powering the main board and the LED lamp string is shown in the figure. Unlike the power supply circuit shown in Figure 18 Figure 19 ​The power supply circuit adopts a "ladder power supply" form, and the LED lamp string is powered by two different secondary side windings in the LLC isolated voltage conversion module. Specifically, the power supply circuit includes three power supply branches. The first power supply branch includes the first secondary side winding in the LLC isolated voltage conversion module and is configured to output a fifth voltage (for example, 12V) to the mainboard. The second power supply branch includes the second secondary side winding in the LLC isolated voltage conversion module and is configured to output a sixth voltage as a fixed voltage. The third power supply branch includes the third secondary side winding in the LLC isolated voltage conversion module and is configured to output a seventh voltage (for example, 16V or 18V). Subsequently, the voltage adjustment module (low-voltage buck / boost) converts the seventh voltage into an eighth voltage and then provides the sum of the seventh voltage and the eighth voltage to the LED lamp string. In the process of supplying power to the LED lamp string, since two different voltages output by the second secondary side winding and the third secondary side winding are flexibly set, and the voltage adjustment module only needs to adjust the voltage output by the secondary side winding with the smaller voltage, the requirement for the withstand voltage value of the switch tube, the capacitor and other elements in the voltage adjustment module is reduced, thereby reducing the area of the PCB on which the power supply circuit is located, and finally reducing the cost of the power supply circuit.

[0134] Figure 20 Another power supply circuit structure diagram for supplying power to the mainboard and the LED lamp string is shown. The mains alternating current (100V-240V, 50-60Hz) obtained by the power supply circuit is input to two PFC modules through the filtering and rectifying module (rectifier bridge) respectively, and each PFC module is connected with an LLC isolated voltage conversion module. One of the LLC isolated voltage conversion modules supplies power to the mainboard and provides 12V voltage, 18V voltage or 9.1V voltage in standby mode, and different voltages can be provided to the mainboard by adjusting the opening and closing frequency or duty cycle of the transistor in the LLC isolated voltage conversion module. The other LLC isolated voltage conversion module provides 10-15V voltage and 18A constant current to the multi-channel or single-channel LED load, and adjusts the output voltage of the LLC module based on the feedback circuit.

[0135] With the development of electronic technology, the integration of electronic devices including display devices such as televisions is becoming higher and higher, which puts forward higher and higher requirements on the power supply of the display device. Figure 18 、 Figure 19 and Figure 20In the display device, the power supply architecture is directly connected with the commercial alternating current, and a special power supply circuit is arranged in the display device power board to perform voltage transformation, direct current conversion and the like on the alternating current, and at least includes the following modules: a rectifier bridge, a power factor correction (PFC) module, and a resonant conversion circuit (LLC) isolation voltage conversion module. The resonant conversion circuit (LLC) isolation voltage conversion module is used to generate a plurality of direct current voltages to meet the power supply requirements of the loads in the display device. Since the power supply architecture includes at least one filter rectifier module, at least one PFC module and at least one LLC isolation voltage conversion module, and the LLC isolation voltage conversion module includes at least one secondary winding, the circuit structure of the power supply is relatively complex, and accordingly, the complex circuit is not conducive to improving the integration.

[0136] With the rise of the power adapter and the popularization of gallium nitride devices, the power supply of the display device gradually develops into an external form, that is, an external power adapter is used to perform voltage transformation, direct current conversion and the like on the alternating current to output a fixed direct current voltage. Figure 21 A schematic diagram of the external adapter power supply mode according to the embodiment of the present application is shown, which shows a structure diagram for supplying power to a display device such as a television under the external adapter power supply mode. As can be seen, the television shown in the display device is connected to the single fixed direct current input voltage provided by the power adapter through a cable. Figure 21

[0137] The display device power supply architecture shown in the above Figure 18 , Figure 19 and Figure 20 is not applicable to the external adapter power supply mode shown in Figure 21 . How to use the single fixed direct current input voltage provided by the external adapter to supply power to the display device load is a problem to be solved.

[0138] Based on the above problems, the display device provided by the present application is provided with a power supply interface connected with the external adapter to receive a direct current input voltage to adapt to the external adapter power supply mode; a superimposed voltage is generated by using the direct current input voltage, and the superimposed voltage is superimposed with the direct current input voltage to realize step power supply, which is conducive to reducing heat loss; the energy storage element is used to realize continuous power supply to the backlight control module; the power supply voltage of the backlight control module is adjusted in real time through real-time feedback to make the light emitting diode work stably.

[0139] The content of the present application and how the content of the present application solves the above technical problems will be described in detail in the following specific embodiments. The following specific embodiments can be combined with each other. The embodiments of the present application will be described below with reference to the drawings.​

[0140] Figure 22 This is a schematic diagram of the power supply circuit structure of a display device according to an embodiment of the present application, including: a backlight control module, a power supply interface, a first voltage conversion module, an energy storage element, and a feedback module.

[0141] A backlight control module is used to control the light emission of a light-emitting diode (LED), which is used to illuminate the screen of the display device; a power supply interface is used to receive a DC input voltage provided by an external adapter; a first voltage conversion module is used to generate a fifth voltage based on the DC input voltage; an energy storage element is connected to the first voltage conversion module and is used to store energy in the fifth voltage; the energy storage element and the first voltage conversion module alternately output the fifth voltage.

[0142] The negative electrode of the backlight control module is connected to a fifth voltage, which serves as a negative reference voltage for the backlight control module. The positive electrode of the backlight control module is connected to a DC input voltage. The feedback module is configured to transmit a feedback signal generated by the backlight control module to the first voltage conversion module. The feedback signal is configured to instruct the first voltage conversion module to adjust the fifth voltage to adjust the required voltage of the backlight control module.

[0143] The voltage across the backlight control module is the sum of the absolute value of the DC input voltage and the fifth voltage. The DC input voltage is equivalent to a "fixed voltage," and the fifth voltage is equivalent to a "variable voltage." This circuit structure, which utilizes both a fixed and variable voltage to power the backlight control module, is known as "stepped power supply." This reduces the withstand voltage requirements of the electrical components within the first voltage conversion module, thereby lowering costs and improving efficiency. It also reduces heat loss in the electrical components.

[0144] like Figure 22 As shown, the external adapter receives AC power (100V-240V, 50-60Hz), and the internal circuit of the external adapter can be as shown. Figure 21 As shown, it at least includes a filter rectifier module, a PFC module, and an LLC isolation voltage conversion module. The external adapter outputs a fixed DC voltage. The display device is provided with a power supply interface connected to the external adapter for receiving a DC input voltage to adapt to the Figure 21 The external adapter power supply mode shown. Figure 18 to Figure 20 , there is no need to set the filter rectifier module, PFC module, and LLC isolation voltage conversion module on the display device power board, which is conducive to simplifying the circuit.

[0145] In some embodiments, Figure 22 The energy storage element shown can be a single energy storage capacitor or other energy storage circuit. The energy storage element cooperates with the first voltage conversion module to alternately output the fifth voltage, continuously providing a negative reference voltage for the backlight control module to ensure stable light emission of the light emitting diode.

[0146] In some embodiments, Figure 22 The first voltage conversion module shown can be in the form of a charge pump. Figure 23 The power supply circuit structure of another display device according to an embodiment of the present application is shown. As shown, Figure 23 The first voltage conversion module includes a charge pump module. The charge pump module is configured to generate a fifth voltage in a charging state and provide the fifth voltage to a negative electrode of the backlight control module in a discharging state. A first end of an energy storage element is connected to a positive output end of the charge pump module and grounded. A second end of the energy storage element is connected to a negative output end of the charge pump module. The energy storage element is configured to store the fifth voltage when the charge pump module is discharging and provide the fifth voltage to the negative electrode of the backlight control module when the charge pump module is charging. A feedback signal is used to instruct the charge pump module to adjust the fifth voltage to adjust the required voltage of the backlight control module.

[0147] The first voltage conversion module in the form of a charge pump in the embodiment is a non-inductive DC-DC power converter. That is, there is no inductive element in the voltage conversion of the charge pump form, and thus the voltage conversion principle does not involve high-speed conversion of a magnetic field, i.e., high-speed conversion of electricity-magnetism and magnetism-electricity. The problem of electromagnetic interference can be almost ignored. The voltage conversion principle of the charge pump form is to use high-speed charging and discharging of internal capacitive elements, and thus has the advantages of low electromagnetic interference, a larger adjustment range of output voltage, high efficiency, small size, low static current, low minimum operating voltage, low noise, and the like. In addition, the integration of capacitors is easier and cheaper than that of inductors, and thus the first voltage conversion module in the form of a charge pump is easier to implement high integration, and the cost of the overall application circuit is also not high.

[0148] In some embodiments, Figure 23 The energy storage element shown can be a single energy storage capacitor or other energy storage circuit. The energy storage element cooperates with the charge pump module to alternately output the fifth voltage to continuously supply power to the backlight control module and stabilize the light emission of the light-emitting diode.

[0149] The principle of power supply of the first voltage conversion module and the energy storage element will be described below in combination with the circuit structure of the charge pump module and the energy storage element.

[0150] In some embodiments, Figure 24 The power supply circuit structure of a charge pump module according to an embodiment of the present application is shown, in which the energy storage element Cn is taken as an example of a single energy storage capacitor. The charge pump module includes a first controller, a first energy storage capacitor C11, a first switch S11, a second switch S12, a third switch S13, and a fourth switch S14.

[0151] The first end of the first switch S11 is connected with a direct current input voltage Vin, and the second end of the first switch S11 is connected with the first end of the second switch S12; the second end of the second switch S12 is connected with the first end of the energy storage element Cn as a positive output end of the charge pump module and is grounded; the first end of the first energy storage capacitor C11 is connected with the second end of the first switch S11 and the first end of the second switch S12, and the second end of the first energy storage capacitor C11 is connected with the first end of the third switch S13 and the first end of the fourth switch S14; the second end of the fourth switch S14 is grounded; the second end of the third switch S13 is connected with the second end of the energy storage element Cn as a negative output end of the charge pump module and outputs a fifth voltage -Vo.

[0152] The first controller is connected with the control ends of the first switch S11, the second switch S12, the third switch S13 and the fourth switch S14, and is used for adjusting the fifth voltage -Vo by controlling the switching frequency of the first switch S11, the second switch S12, the third switch S13 and the fourth switch S14 according to a feedback signal; wherein the switching states of the first switch S11 and the second switch S12 are different, and the first switch S11 and the fourth switch S14 are simultaneously turned off or turned on; and the second switch S12 and the third switch S13 are simultaneously turned off or turned on.

[0153] Based on Figure 24 The principle that the charge pump module cooperates with the energy storage element to provide a negative reference voltage for the negative electrode of the backlight control module is as follows:

[0154] Step (1): the first controller controls the first switch S11 and the fourth switch S14 to be simultaneously closed, and the second switch S12 and the third switch S13 to be simultaneously opened. At this time, the direct current input voltage Vin charges the first energy storage capacitor C11 through the closed first switch S11, and the charging time of the first energy storage capacitor C11 is controlled by controlling the opening time of the second switch S12 and the third switch S13 and the closing time of the first switch S11 and the fourth switch S14, so as to control the energy storage voltage of the first energy storage capacitor C11. Assuming that the energy storage voltage of the first energy storage capacitor C11 is Vo after charging, at this time, since the second end of the first energy storage capacitor C11 is grounded, the voltage at the first end of the first energy storage capacitor C11 is Vo.

[0155] Step (2): The first controller controls the first switch S11 and the fourth switch S14 to be opened at the same time, and the second switch S12 and the third switch S13 to be closed at the same time. At this time, the first terminal of the first energy storage capacitor C11 is grounded, so the voltage of the second terminal of the first energy storage capacitor C11 is -Vo (i.e. the fifth voltage), which is used to provide a negative reference voltage to the negative electrode of the backlight control module. At the same time, the first energy storage capacitor C11 charges the energy storage element Cn, so that the energy storage voltage of the charged energy storage element Cn is Vo. Since the first terminal of the energy storage element Cn is also grounded, the second terminal of the energy storage element Cn is -Vo (i.e. the fifth voltage).

[0156] Step (3): The first controller controls the first switch S11 and the fourth switch S14 to be closed at the same time, and the second switch S12 and the third switch S13 to be opened at the same time. Repeat the charging process of the first energy storage capacitor C11 in step (1). At this time, the first terminal of the energy storage element Cn is grounded, and the second terminal of the energy storage element Cn provides a negative reference voltage to the negative electrode of the backlight control module, i.e. the fifth voltage -Vo.

[0157] The power supply circuit shown in Figure 24 generates the fifth voltage -Vo based on the direct current input voltage Vin, and connects the fifth voltage -Vo to the negative electrode of the backlight control module as a negative reference voltage of the backlight control module; in combination with the direct current input voltage Vin input to the positive electrode of the backlight control module, the voltage across the backlight control module is the sum of the direct current input voltage Vin and the absolute value Vo of the fifth voltage, i.e. the demand voltage Vled of the backlight control module is equal to Vin+Vo.

[0158] For the power supply circuit shown in Figure 24 , only the size of the fifth voltage -Vo needs to be controlled to control the change of the demand voltage Vled of the backlight control module. The first controller controls the number of charges transferred by controlling the switching frequency or duty cycle of the first switch S11, the second switch S12, the third switch S13 and the fourth switch S14 based on the feedback signal, so as to control the demand voltage Vled of the backlight control module.

[0159] The direct current input voltage Vin is relatively stable, which is equivalent to a "fixed voltage"; the fifth voltage -Vo is equivalent to a "variable voltage". Since the direct current input voltage Vin is relatively stable, the output voltage variation range of the fifth voltage -Vo depends on the variation range required by the demand voltage Vled of the backlight control module. The above-mentioned circuit structure for supplying power to the backlight control module by using fixed voltage and variable voltage is a "step power supply", which can reduce the voltage withstand value requirements of the electrical elements in the first voltage conversion module, so as to achieve the purposes of reducing cost and improving efficiency; at the same time, the heat loss on the electrical elements can be reduced.

[0160] In some embodiments, Figure 22The first voltage conversion module shown can be in the form of a flyback isolation. Figure 25 The figure shows a power supply circuit structure of yet another display device according to an embodiment of the present application. As shown in the figure, the first voltage conversion module includes a flyback isolation voltage conversion module. Figure 25 The first voltage conversion module shown can be in the form of a flyback isolation.

[0161] The flyback isolation voltage conversion module is configured to generate a fifth voltage from the secondary winding when the primary winding is conducting and deliver the fifth voltage to the negative electrode of the backlight control module. The first end of the energy storage element is connected to the positive output end of the flyback isolation voltage conversion module and grounded. The second end of the energy storage element is connected to the negative output end of the flyback isolation voltage conversion module. The energy storage element is configured to store the fifth voltage when the primary winding is conducting and provide the fifth voltage to the negative electrode of the backlight control module when the primary winding is off. The feedback signal is configured to instruct the flyback isolation voltage conversion module to adjust the fifth voltage to adjust the required voltage of the backlight control module.

[0162] Specifically, the flyback isolation voltage conversion module adopted in the embodiment is electrically isolated by the primary winding and the secondary winding. The term "flyback" refers to the fact that when the switch tube is on, the secondary winding transformer acts as an inductor, and the electrical energy is converted into magnetic energy, at which time there is no current in the output circuit. On the contrary, when the switch tube is off, the secondary winding transformer releases energy, and the magnetic energy is converted into electrical energy, and there is current in the output circuit. In the flyback voltage conversion module, the secondary winding transformer also acts as an energy storage inductor, which has the characteristics of fewer components, simpler circuit, lower cost, smaller size, etc. At the same time, electrical isolation improves the safety of use.

[0163] In some embodiments, Figure 25 The energy storage element shown can be a single energy storage capacitor or other energy storage circuit. The energy storage element cooperates with the flyback isolation voltage conversion module to alternately output the fifth voltage, continuously provide a negative reference voltage for the backlight control module, and stabilize the light emission of the light-emitting diode.

[0164] The principle of power supply of the first voltage conversion module and the energy storage element will be described below in combination with the circuit structure of the flyback isolation voltage conversion module and the energy storage element.

[0165] In some embodiments, Figure 26 The figure shows a power supply circuit structure of a flyback isolation voltage conversion module according to an embodiment of the present application. The flyback isolation voltage conversion module includes a primary winding, a secondary winding, a first diode D11, a second controller, and a fifth switch S15.

[0166] The first end of the primary winding is connected to a direct current input voltage Vin, the second end of the primary winding is connected to the first end of the fifth switch S15, and the second end of the fifth switch S15 is grounded; the secondary winding is coupled with the primary winding, and the first end of the secondary winding is connected to the anode of the first diode D11; the cathode of the first diode D11 is used as a positive output end of the flyback isolation transformer module, is connected to the first end of the energy storage element Cn, and is grounded; the second end of the secondary winding is used as a negative output end of the flyback isolation transformer module, is connected to the second end of the energy storage element Cn, and outputs a fifth voltage -Vo.

[0167] The second controller is connected to the control end of the fifth switch S15, and is used for adjusting the fifth voltage -Vo by controlling the switching frequency of the fifth switch S15 according to a feedback signal.

[0168] Based on Figure 26 The principle that the flyback isolation transformer module and the energy storage element cooperate to provide a negative reference voltage for the negative pole of the backlight control module is as follows:

[0169] Step (1): The second controller controls the fifth switch S15 to be turned on, the current of the primary winding linearly increases, and the energy storage of the inductor increases; the first diode D11 is not conductive. The energy storage voltage of the primary winding can be controlled by controlling the switching frequency of the fifth switch S15.

[0170] Step (2): The second controller controls the fifth switch S15 to be turned off, the current of the primary winding is cut off, and the first diode D11 is conductive. The first end of the secondary winding is grounded through the first diode D11, and by setting the turns ratio of the primary winding and the secondary winding, the second end of the secondary winding can output the fifth voltage -Vo, which is used for providing a negative reference voltage for the negative pole of the backlight control module. At the same time, the secondary winding charges the energy storage element Cn, so that the energy storage voltage of the charged energy storage element Cn is Vo. Since the first end of the energy storage element Cn is also grounded, the second end of the energy storage element Cn is -Vo (i.e. the fifth voltage).

[0171] Step (3): The second controller controls the fifth switch S15 to be turned on, and the energy storage process of the primary winding is repeated in step (1). At this time, the first end of the energy storage element Cn is grounded, and the second end of the energy storage element Cn provides a negative reference voltage for the negative pole of the backlight control module, i.e. the fifth voltage -Vo.

[0172] The above Figure 26The power supply circuit shown generates a fifth voltage -Vo based on a direct current input voltage Vin, and connects the fifth voltage -Vo to the negative pole of the backlight control module as a negative reference voltage of the backlight control module; in combination with the direct current input voltage Vin input to the positive pole of the backlight control module, the voltage across the backlight control module is the sum of the direct current input voltage Vin and the absolute value of the fifth voltage Vo, that is, the required voltage Vled of the backlight control module is equal to Vin+Vo.

[0173] For Figure 26 In the power supply circuit shown, only the size of the fifth voltage -Vo needs to be controlled to control the change of the required voltage Vled of the backlight control module. The second controller controls the number of charges transmitted by controlling the switching frequency or duty cycle of the fifth switch S15 based on the feedback signal, so as to achieve the purpose of controlling the required voltage Vled of the backlight control module.

[0174] The direct current input voltage Vin is relatively stable, which is equivalent to a "fixed voltage"; the fifth voltage -Vo is equivalent to a "variable voltage". Since the direct current input voltage Vin is relatively stable, the output voltage variation range of the fifth voltage -Vo depends on the required variation range of the required voltage Vled of the backlight control module. The above-mentioned circuit structure for supplying power to the backlight control module by using a fixed voltage and a variable voltage is a "step power supply", which can reduce the voltage withstand value requirements of the electrical components in the first voltage conversion module, so as to achieve the purposes of reducing cost and improving efficiency; at the same time, the heat loss on the electrical components can be reduced.

[0175] Figure 27 A structure diagram of a level conversion circuit according to an embodiment of the present application. In some embodiments, the feedback module includes a level conversion circuit. The level conversion circuit receives a first feedback signal output by the backlight control module, converts the first feedback signal into a second feedback signal, and then outputs the second feedback signal to the first voltage conversion module; wherein the reference voltages of the first feedback signal and the second feedback signal are different.

[0176] Since the reference voltage of the backlight control module is -Vo and the reference voltage of the first voltage conversion module is 0, the first feedback signal generated by the backlight control module cannot be directly sent to the first voltage conversion module, therefore, the level conversion circuit is used to convert the first feedback signal with a low reference voltage of -Vo into a second feedback signal with a reference voltage of 0. The level conversion circuit can refer to related technologies.

[0177] In some embodiments of the display device, a first filtering module is further included; the first filtering module is connected with the power supply interface and the first voltage conversion module, and is used for filtering the direct current input voltage. The first filtering module can be a filtering circuit composed of one or more grounding capacitors, or a filtering circuit composed of capacitors and inductors. For example, Figure 27As shown, the first filter module takes the first filter capacitor C13 as an example, and the DC input voltage of the power supply interface and the ground are connected in parallel with the first filter capacitor C13. It is used to filter out the noise and AC components of the power supply, smooth the pulsed DC voltage, and store electrical energy. The capacitance of the capacitor is related to the load current and the purity of the power supply, and a large-capacity filter capacitor is usually selected.

[0178] In some embodiments, the first filter capacitor C13 can be an electrolytic capacitor. Figure 27 As shown, the electrolytic capacitor is a kind of capacitor, the metal foil is the positive electrode (aluminum or tantalum), and the metal oxide film (aluminum oxide or tantalum pentoxide) close to the positive electrode is the dielectric. The cathode is composed of conductive material, electrolyte (the electrolyte can be liquid or solid) and other materials, because the electrolyte is the main part of the cathode. The capacitance per unit volume is very large, because the preparation material is ordinary industrial material, and the preparation process is ordinary industrial equipment, so batch production can be carried out, so the cost is relatively low. It should be noted that the positive and negative of the electrolytic capacitor cannot be connected in reverse.

[0179] In some embodiments, the first filter capacitor C13 can also be other types of capacitors, such as ceramic capacitors, thin film capacitors, mica capacitors, etc. In actual circuits, you can choose according to the capacitance requirement.

[0180] In some embodiments of the display device, a second filter module is further included; the second filter module is arranged between the positive electrode and the negative electrode of the backlight control module. The second filter module can be a filter circuit composed of one or more grounding capacitors, or a filter circuit composed of capacitors and inductors. As shown, Figure 27 As shown, the second filter module takes the second filter capacitor C14 as an example, which is used to stabilize the voltage across the backlight control module.

[0181] In some embodiments of the display device, a third filter module is further arranged, which is used to filter out the noise in the DC input voltage Vin input to the positive electrode of the backlight control module. As shown, Figure 27 As shown, the third filter module takes the third filter capacitor C15 as an example, one end of the third filter capacitor C15 is connected to the DC input voltage Vin, and the other end of the third filter capacitor C15 is grounded.

[0182] In some embodiments of the display device, a second diode Dn is further included; the positive electrode of the second diode Dn is connected to the second end of the energy storage element Cn, and the negative electrode of the second diode Dn is connected to the first end of the energy storage element Cn. The fourth diode Dn makes the backlight control module and the negative electrode of the power supply interface form a current loop, prevents the current from flowing through the first voltage conversion module when the first voltage conversion module is not working, and causes system malfunction or other abnormal conditions, and plays a role in protecting the first voltage conversion module.

[0183] In some embodiments,Figure 28 FIG. 1 is a structural schematic diagram of a level conversion circuit based on a charge pump module power supply circuit according to an embodiment of the present application. The charge pump module is used to Figure 24 For example, the power supply principle will not be repeated. In some embodiments, Figure 29 FIG. 2 is a structural schematic diagram of a level conversion circuit based on a flyback isolation transformer module power supply circuit according to an embodiment of the present application. The flyback isolation transformer module is used to Figure 26 For example, the power supply principle will not be repeated.

[0184] In some embodiments, the display device provided by the present embodiment further comprises a mainboard; the mainboard is connected with the power supply interface, and the direct current input voltage is used to supply power to the mainboard. Figure 30 FIG. 3 is a structural schematic diagram of a circuit for supplying power to a mainboard according to an embodiment of the present application. When the direct current input voltage is equal to the required voltage of the mainboard, the direct current input voltage can be selected to directly supply power to the mainboard.

[0185] In the display device of some embodiments, a second voltage conversion module is further included; the second voltage conversion module is connected with the power supply interface and the mainboard, and is used to output a sixth voltage according to the direct current input voltage, the sixth voltage being the required voltage of the mainboard. Figure 31 FIG. 4 is a structural schematic diagram of another circuit for supplying power to a mainboard according to an embodiment of the present application. When the direct current input voltage does not meet the required voltage of the mainboard, a second voltage conversion module can be used to perform DC-DC voltage conversion on the direct current input voltage. When the television power is large, in order to reduce the loss of the cable, the voltage can be increased and the current can be reduced, so the direct current input voltage can be higher than the required voltage of the mainboard. In some embodiments, since the mainboard usually requires a fixed voltage, the second voltage conversion module can use a buck voltage reduction circuit, a boost-buck voltage increase and reduction circuit, etc.

[0186] The present embodiment further provides a display control method applied to the display device described above, and the display control method comprises: receiving a feedback signal, the feedback signal being generated by a backlight control module and sent through a feedback module; and adjusting a fifth voltage based on the feedback signal to adjust the required voltage of the backlight control module. In the present embodiment, the fifth voltage generated by the first voltage conversion module is adjusted according to the feedback signal of the real-time current output by the backlight control module, and then the required voltage of the backlight control module is adjusted, so that the backlight control module works at the rated current, and the damage of the components caused by the excessive current flowing through the LED components in the LED lamp string is prevented.

[0187] According to the display device provided in the embodiment of the present application, the backlight control module is used for controlling the light emitting diode to emit light, the light emitting diode is used for lighting the screen of the display device, the power supply interface is used for receiving the direct current input voltage provided by the external adapter, the first voltage conversion module is used for generating the fifth voltage according to the direct current input voltage, the energy storage element is connected with the first voltage conversion module and is used for storing the fifth voltage, the energy storage element and the first voltage conversion module alternately output the fifth voltage, the negative electrode of the backlight control module is connected with the fifth voltage, and the fifth voltage is used as the negative reference voltage of the backlight control module; the positive electrode of the backlight control module is connected with the direct current input voltage; the sum of the absolute value of the direct current input voltage and the absolute value of the fifth voltage is equal to the required voltage of the backlight control module; and the feedback module is used for sending the feedback signal generated by the backlight control module to the first voltage conversion module, and the feedback signal is used for instructing the first voltage conversion module to adjust the fifth voltage so as to adjust the required voltage of the backlight control module.

[0188] The power supply interface connected with the external adapter is arranged in the embodiment of the present application, the direct current input voltage is received, and the power supply mode of the external adapter is adapted; the fifth voltage generated by the direct current input voltage is used as the negative reference voltage of the backlight control module, and the direct current input voltage connected with the positive electrode of the backlight control module constitutes the stepped power supply, which is beneficial to reduce the heat loss; the energy storage element is used for continuously supplying power to the backlight control module; and the power supply voltage of the backlight control module is adjusted in real time through real-time feedback, so that the light emitting diode works stably.

[0189] In order to meet the power supply demand of the load in the display device by using the direct current voltage output by the external adapter, the present application further provides the following embodiments.

[0190] The display device provided in the present application is provided with the power supply interface connected with the external adapter, receives the direct current input voltage, and adapts to the power supply mode of the external adapter; the superimposed voltage is generated by using the direct current input voltage, and the superimposed voltage is superimposed with the direct current input voltage, so as to realize the stepped power supply, which is beneficial to reduce the heat loss; the energy storage element is used for continuously supplying power to the backlight control module; and the power supply voltage of the backlight control module is adjusted in real time through real-time feedback, so that the light emitting diode works stably.

[0191] The content of the present application and how the content of the present application solves the above technical problems will be described in detail in the following specific embodiments. The following specific embodiments can be combined with each other. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0192] Figure 32 The power supply circuit structure of the display device according to the embodiment of the present application includes a backlight control module, a power supply interface, a third voltage conversion module, an energy storage element, and a feedback module.

[0193] The backlight control module is configured to control the light-emitting diode to emit light to light up the screen of the display device. The power supply interface is configured to receive a direct current input voltage provided by an external adapter. The third voltage conversion module is configured to generate a superimposed voltage based on the direct current input voltage, superimpose the superimposed voltage and the direct current input voltage, and output a ninth voltage after superimposition. The ninth voltage is a required voltage of the backlight control module. The first end of the energy storage element is connected to the third voltage conversion module, and the second end of the energy storage element is connected to the direct current input voltage. The energy storage element is configured to store the superimposed voltage and alternately output the ninth voltage with the third voltage conversion module. The feedback module is configured to send a feedback signal generated by the backlight control module to the third voltage conversion module. The feedback signal is configured to instruct the third voltage conversion module to adjust the ninth voltage.

[0194] As shown in Figure 32 , the external adapter receives alternating current (100V-240V, 50-60Hz) from the mains. The internal circuit of the external adapter can include at least a filter rectifier module, a PFC module, and an LLC isolated voltage conversion module, as shown in Figure 21 . The external adapter outputs a fixed direct current voltage. The display device is provided with a power supply interface connected to the external adapter, which is configured to receive a direct current input voltage to adapt to the external adapter power supply mode as shown in Figure 21 . Compared with Figure 18 to Figure 20 , the filter rectifier module, the PFC module, and the LLC isolated voltage conversion module do not need to be arranged on the display device power board, which is beneficial to simplify the circuit.

[0195] In some embodiments, the energy storage element shown in Figure 32 may be a single energy storage capacitor or other energy storage circuit. The energy storage element cooperates with the third voltage conversion module to alternately output the ninth voltage, which continuously supplies power to the backlight control module to stabilize the light-emitting diode.

[0196] In some embodiments, the third voltage conversion module shown in Figure 32 may be in the form of a charge pump. Figure 33 Another power supply circuit structure diagram of a display device according to an embodiment of the present application is shown in Figure 33 . The third voltage conversion module includes a charge pump module configured to generate a superimposed voltage in a charging state, superimpose the superimposed voltage and a direct current input voltage to generate a ninth voltage in a discharging state, and output the superimposed ninth voltage to the backlight control module. The first end of the energy storage element is connected to the output end of the charge pump module. The energy storage element is configured to store the superimposed voltage when the charge pump module is discharging, and superimpose the superimposed voltage on the direct current input voltage when the charge pump module is charging, and output the superimposed ninth voltage to the backlight control module. The feedback signal is configured to instruct the charge pump module to adjust the ninth voltage by adjusting the superimposed voltage.

[0197] Specifically, the third voltage conversion module in the form of a charge pump in the embodiment is a non-inductive DC-DC power converter, that is, there is no inductive element in the voltage conversion in the form of a charge pump, and thus the voltage conversion principle does not involve high-speed conversion of a magnetic field, that is, high-speed conversion of electricity-magnetism and magnetism-electricity, and electromagnetic interference problems can be almost ignored. The voltage conversion principle in the form of a charge pump is to use high-speed charging and discharging of internal capacitive elements, and thus has the advantages of low electromagnetic interference. In addition to low electromagnetic interference, the third voltage conversion module in the form of a charge pump also has the advantages of a larger adjustment range of an output voltage, high efficiency, small size, low quiescent current, low minimum operating voltage, low noise, and the like. In addition, integration of capacitors is easier and cheaper than integration of inductors, and thus the third voltage conversion module in the form of a charge pump is easier to achieve high integration, and the cost of the overall application circuit is also not high.

[0198] In some embodiments, Figure 33 The energy storage element shown can be a single energy storage capacitor or other energy storage circuit. The energy storage element cooperates with the charge pump module to alternately output the ninth voltage to continuously supply power to the backlight control module, so that the light-emitting diode stably emits light.

[0199] The principle of power supply cooperation between the third voltage conversion module and the energy storage element will be described below in combination with a specific circuit structure schematic diagram of the charge pump module and the energy storage element.

[0200] In some embodiments, Figure 34 A power supply circuit structure schematic diagram of a charge pump module according to an embodiment of the present application is shown. The charge pump module includes a first controller, a first energy storage capacitor C11, a first diode D11, a second diode D12, a first switch S1, and a second switch S2.

[0201] The positive electrode of the first diode D11 is connected to a direct current input voltage Vin, and the negative electrode of the first diode D11 is connected to the positive electrode of the second diode D12. The negative electrode of the second diode D12 is an output end of the charge pump module and outputs a ninth voltage Vled. The first end of the first switch S1 is connected to the positive electrode of the first diode D11, the second end of the first switch S1 is connected to the first end of the second switch S2, and the second end of the second switch S2 is grounded. The first end of the first energy storage capacitor C11 is connected to the negative electrode of the first diode D11, and the second end of the first energy storage capacitor C11 is connected to the second end of the first switch S1.

[0202] The first controller is connected to the control ends of the first switch S1 and the second switch S2, and is used to control the switching frequency of the first switch S1 and the second switch S2 according to a feedback signal to adjust the superimposed voltage. The switching states of the first switch S1 and the second switch S2 are different.

[0203] As Figure 34As shown, the energy storage element takes a single energy storage capacitor as an example. The second end of the energy storage element Cn is connected to the DC input voltage Vin, that is, the second end of the energy storage element is applied with the DC input voltage Vin. The second end of the energy storage element can be applied with the DC input voltage Vin by establishing a physical connection between the second end of the energy storage element Cn and the power supply interface.

[0204] Based on Figure 34 As shown in the power supply circuit, the principle of cooperation of the third voltage conversion module and the energy storage element for power supply is as follows:

[0205] Step (1): The first controller controls the first switch S1 to be open and the second switch S2 to be closed. At this time, the DC input voltage Vin charges the first energy storage capacitor C11 through the first diode D11, so that the first end of the first energy storage capacitor C11 is positive. The charging time of the first energy storage capacitor C11 is controlled by controlling the opening time of the first switch S1 and the closing time of the second switch S2, and then the energy storage voltage of the first energy storage capacitor C11 is controlled. Assuming that the energy storage voltage of the first energy storage capacitor C11 after charging is Vo (i.e. the superimposed voltage), since its second end is grounded, the voltage at its first end is Vo.

[0206] Step (2): The first controller controls the first switch S1 to be closed and the second switch S2 to be open. At this time, the DC input voltage Vin is connected to the second end of the first energy storage capacitor C11 through the first switch S1, and the first energy storage capacitor C11 is regarded as a battery with the upper end (i.e. the first end) being positive and the lower end (i.e. the second end) being negative. Therefore, connecting the DC input voltage Vin to the lower end of the first energy storage capacitor C11 is equivalent to connecting two power supplies in series, that is, voltage superposition is performed. Therefore, the first energy storage capacitor C11 outputs the superimposed ninth voltage Vled through the negative electrode of the second diode D12, where Vled equals Vin+Vo. At this time, for the energy storage element Cn, the first end is connected to the voltage Vled, and the second end is connected to the voltage Vin. Therefore, the energy storage element Cn is charged, and the energy storage voltage difference of Cn is Vo (i.e. the superimposed voltage).

[0207] Step (3): The first controller controls the first switch S1 to be open and the second switch S2 to be closed, and the charging process of the first energy storage capacitor C11 in step (1) is repeated. At the same time, the energy storage element Cn is regarded as a battery with the upper end (i.e. the first end) being positive and the lower end (i.e. the second end) being negative. Therefore, connecting the DC input voltage Vin to the second end of the energy storage element Cn is equivalent to connecting two power supplies in series, that is, voltage superposition is performed. Therefore, the superimposed ninth voltage Vled is output through the first end of the energy storage element Cn. Since the anode voltage of the second diode D12 is Vin and the cathode voltage is Vled, the second diode D12 is not conductive.

[0208] For Figure 34In the power supply circuit shown, the change of the ninth voltage Vled can be controlled by simply controlling the magnitude of the superimposed voltage Vo. The first controller controls the amount of charge transfer by controlling the switching frequency or duty cycle of the first switch S1 and the second switch S2 based on the feedback signal, thereby achieving the purpose of controlling the ninth voltage Vled. The DC input voltage Vin is relatively stable, equivalent to a "fixed voltage"; the superimposed voltage Vo is equivalent to a "variable voltage." Since the DC input voltage Vin is relatively stable, the output voltage variation range of the superimposed voltage Vo depends on the required variation range of the ninth voltage Vled. The above-mentioned circuit structure of using a "fixed voltage" superimposed on a "variable voltage" is called "stepped power supply", which can achieve the purpose of reducing costs and improving efficiency.

[0209] In some embodiments, Figure 34 The power supply circuit shown is compared with a traditional DC-DC conversion solution. Traditional DC-DC conversion solutions use a DC-DC circuit module to convert a DC input voltage to a required voltage. Specifically, the DC-DC circuit module can be a boost circuit, a buck circuit, a boost-buck circuit, or other circuits with boost and voltage reduction functions.

[0210] For 12V LED components, the operating voltage typically ranges from 11.4 to 12.6V. For a string of four LED components, the supply voltage ranges from 45.6 to 50.4V. Assuming an input voltage of 42V, Vled needs to be 50V, for a total output power of 100W.

[0211] Taking a boost circuit as an example of a traditional DC-DC conversion solution, assuming that the efficiency of the boost circuit is 95%, the input power is 100W / 0.95=105.2W, and the heat loss is 5.2W.

[0212] based on Figure 34 Consider the power supply circuit shown below: assuming an 8V superimposed voltage Vo, a 42V input, and a 2A output current. Assuming a 90% charge pump module efficiency, the output power is 16W, while the input power is 16W / 0.9 = 17.8W, resulting in a heat loss of 1.8W. The overall conversion efficiency is: 100W / (42V × 2A + 17.8W) = 98.2%. This represents an efficiency improvement of 98.2% - 95% = 3.2%. Furthermore, the significant reduction in converter power also reduces costs.

[0213] In some embodiments, Figure 34 In the power supply circuit shown, the second end of the energy storage element Cn may also be grounded. Figure 35Fig. 2 is a schematic diagram of a power supply circuit structure of another charge pump module according to an embodiment of the present application. Compared with Figure 34 The difference is that the second end of the energy storage element Cn is grounded. Therefore, Figure 35 The difference in the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different. Figure 34 The difference in the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different.

[0214] Based on the power supply circuit shown in Fig. 1, the power supply principle of the third voltage conversion module cooperating with the energy storage element is as follows: Figure 35 Step (1): The first controller controls the first switch S1 to be open and the second switch S2 to be closed. At this time, the direct current input voltage Vin charges the first energy storage capacitor C11 through the first diode D11, so that the first end of the first energy storage capacitor C11 is positive. The charging time of the first energy storage capacitor C11 is controlled by controlling the open time of the first switch S1 and the closed time of the second switch S2, and then the energy storage voltage of the first energy storage capacitor C11 is controlled. Assuming that the energy storage voltage of the first energy storage capacitor C11 after charging is Vo (i.e. the superimposed voltage), since its second end is grounded, the voltage at its first end is Vo.

[0215] Step (2): The first controller controls the first switch S1 to be closed and the second switch S2 to be open. At this time, the direct current input voltage Vin is connected to the second end of the first energy storage capacitor C11 through the first switch S1, and the first energy storage capacitor C11 is regarded as a battery with the upper end (i.e. the first end) being positive and the lower end (i.e. the second end) being negative. Therefore, connecting the direct current input voltage Vin to the lower end of the first energy storage capacitor C11 is equivalent to connecting two power supplies in series, i.e. voltage superposition is performed. Therefore, the first energy storage capacitor C11 outputs the superimposed ninth voltage Vled through the negative electrode of the second diode D12, where Vled equals Vin+Vo. At this time, for the energy storage element Cn, the voltage at its first end is Vled and the voltage at its second end is 0, so the energy storage element Cn is charged and the energy storage voltage difference of Cn is Vled.

[0216] Step (3): The first controller controls the first switch S1 to be open and the second switch S2 to be closed, and the charging process of the first energy storage capacitor C11 in step (1) is repeated. At this time, the energy storage element Cn acts as a power supply to output Vled to supply power to the backlight control module. Since the positive electrode voltage of the second diode D12 is Vin and the negative electrode voltage is Vled, the second diode D12 is not conductive.

[0217] The difference in the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different.

[0218] Compared with the power supply circuit shown in Fig. 1, the power supply circuit shown in Fig. 2 has a lower energy storage requirement for the energy storage element Cn. The lower energy storage requirement corresponds to a lower cost. Figure 34 The difference in the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different. Figure 35 Compared with the power supply circuit shown in Fig. 1, the power supply circuit shown in Fig. 2 has a lower energy storage requirement for the energy storage element Cn. The lower energy storage requirement corresponds to a lower cost. Figure 34 The difference in the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different. Figure 11 Compared with the power supply circuit shown in Fig. 1, the power supply circuit shown in Fig. 2 has a lower energy storage requirement for the energy storage element Cn. The lower energy storage requirement corresponds to a lower cost.

[0219] In some embodiments, Figure 34 and Figure 35 In the power supply circuit shown, the first diode D11 and the second diode D12 can be replaced by switching elements. Figure 36 FIG2 is a schematic diagram of a power supply circuit structure of another charge pump module according to an embodiment of the present application. The charge pump module includes: a second controller, a second energy storage capacitor C12, a third switch S3, a fourth switch S4, a fifth switch S5, and a sixth switch S6.

[0220] A first end of the third switch S3 is connected to the DC input voltage Vin, and a second end of the third switch S3 is connected to a first end of the fourth switch S4; a second end of the fourth switch S4 serves as an output end of the charge pump module, outputting a ninth voltage Vled; a first end of the fifth switch S5 is connected to a first end of the third switch S3, a second end of the fifth switch S5 is connected to a first end of the sixth switch S6, and a second end of the sixth switch S6 is grounded; a first end of the second energy storage capacitor C12 is connected to a second end of the third switch S3, and a second end of the second energy storage capacitor C12 is connected to a second end of the fifth switch S5.

[0221] The second controller is connected to the control terminals of the third switch S3, the fourth switch S4, the fifth switch S5, and the sixth switch S6, and is configured to adjust the superimposed voltage by controlling the switching frequencies of the third switch S3, the fourth switch S4, the fifth switch S5, and the sixth switch S6 according to the feedback signal. The third switch S3 and the fourth switch S4 have different switching states, such that the third switch S3 and the sixth switch S6 are simultaneously disconnected or connected, and the fourth switch S4 and the fifth switch S5 are simultaneously disconnected or connected.

[0222] based on Figure 36 In the power supply circuit shown, the principle of the third voltage conversion module and the energy storage element cooperating to provide power is as follows:

[0223] Step (1): The second controller controls the fourth switch S4 and the fifth switch S5 to be disconnected at the same time, and the third switch S3 and the sixth switch S6 to be closed at the same time. At this time, the DC input voltage Vin charges the second energy storage capacitor C12 through the closed third switch S3, so that the first end of the second energy storage capacitor C12 is a positive voltage. By controlling the disconnection time of the fourth switch S4 and the fifth switch S5, and the closing time of the third switch S3 and the sixth switch S6, the charging time of the second energy storage capacitor C12 is controlled, and then the energy storage voltage of the second energy storage capacitor C12 is controlled. Assuming that the energy storage voltage of the second energy storage capacitor C12 after charging is Vo (i.e., superimposed voltage), since its second end is grounded, the voltage of its first end is Vo.

[0224] Step (2): The second controller controls the fourth switch S4 and the fifth switch S5 to be closed at the same time, and the third switch S3 and the sixth switch S6 to be disconnected, at this time, the direct current input voltage Vin is connected to the second end of the second energy storage capacitor C12 through the fifth switch S5 and the second end of the second energy storage capacitor C12, and the second energy storage capacitor C12 is regarded as a battery with the upper end (i.e. the first end) being the positive pole and the lower end (i.e. the second end) being the negative pole, then the connection of the direct current input voltage Vin to the lower end of the second energy storage capacitor C12 is equivalent to the connection of two power sources in series, i.e. the voltage superposition is performed. Therefore, the second energy storage capacitor C12 outputs the superimposed ninth voltage Vled through the fourth switch S4, where Vled equals Vin+Vo. At this time, for the energy storage element Cn, the first end is connected to the voltage Vled and the second end is connected to the voltage Vin, therefore, the energy storage element Cn is charged and the energy storage voltage difference of Cn is Vo.

[0225] Step (3): The second controller controls the fourth switch S4 and the fifth switch S5 to be disconnected at the same time, and the third switch S3 and the sixth switch S6 to be closed at the same time, and the charging process of the second energy storage capacitor C12 in step (1) is repeated. At the same time, the energy storage element Cn is regarded as a battery with the upper end (i.e. the first end) being the positive pole and the lower end (i.e. the second end) being the negative pole, then the connection of the direct current input voltage Vin to the second end of the energy storage element Cn is equivalent to the connection of two power sources in series, i.e. the voltage superposition is performed. Therefore, the superimposed ninth voltage Vin+Vo, i.e. Vled, is output through the first end of the energy storage element Cn.

[0226] For Figure 36 In the circuit shown in FIG. 6, only the size of the superimposed voltage Vo needs to be controlled to control the change of the ninth voltage Vled. The second controller controls the number of charge transfers by controlling the switching frequency or the duty cycle of the third switch S3, the fourth switch S4, the fifth switch S5 and the sixth switch S6 based on the feedback signal, so as to achieve the purpose of controlling the ninth voltage Vled. The direct current input voltage Vin is relatively stable, which is equivalent to a "fixed voltage"; the superimposed voltage Vo is equivalent to a "variable voltage". Since the direct current input voltage Vin is relatively stable, the output voltage change range of the superimposed voltage Vo depends on the required change range of the ninth voltage Vled. The above-mentioned circuit structure of superimposing a "fixed voltage" with a "variable voltage" is a "step power supply", which can achieve the purposes of reducing cost and improving efficiency.

[0227] In some embodiments, Figure 36 In the power supply circuit shown in FIG. 6, the second end of the energy storage element Cn can also be grounded. Figure 37 FIG. 7 is a schematic diagram of another power supply circuit structure of a charge pump module according to an embodiment of the present application. Compared with Figure 36 The difference is that the second end of the energy storage element Cn is grounded. Therefore, Figure 37 Compared with Figure 36The difference in the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different.

[0228] based on Figure 37 In the power supply circuit shown, the principle of the third voltage conversion module and the energy storage element cooperating to provide power is as follows:

[0229] Step (1): The second controller controls the fourth switch S4 and the fifth switch S5 to be disconnected at the same time, and the third switch S3 and the sixth switch S6 to be closed at the same time. At this time, the DC input voltage Vin charges the second energy storage capacitor C12 through the closed third switch S3, so that the first end of the second energy storage capacitor C12 is a positive voltage. By controlling the disconnection time of the fourth switch S4 and the fifth switch S5, and the closing time of the third switch S3 and the sixth switch S6, the charging time of the second energy storage capacitor C12 is controlled, and then the energy storage voltage of the second energy storage capacitor C12 is controlled. Assuming that the energy storage voltage of the second energy storage capacitor C12 after charging is Vo (i.e., superimposed voltage), since its second end is grounded, the voltage of its first end is Vo.

[0230] Step (2): The second controller controls the fourth switch S4 and the fifth switch S5 to be closed simultaneously, and the third switch S3 and the sixth switch S6 to be opened. At this time, the DC input voltage Vin is connected to the second end of the second energy storage capacitor C12 through the fifth switch S5. The second energy storage capacitor C12 is regarded as a battery with the upper end (i.e., the first end) as the positive pole and the lower end (i.e., the second end) as the negative pole. Then, the DC input voltage Vin connected to the lower end of the second energy storage capacitor C12 is equivalent to two power supplies connected in series, that is, voltage superposition is performed. Therefore, the second energy storage capacitor C12 outputs the superimposed ninth voltage Vled through the fourth switch S4, where Vled is equal to Vin+Vo. At this time, for the energy storage element Cn, its first end is connected to the voltage Vled and its second end is connected to the voltage 0. Therefore, the energy storage element Cn is charged, and the Cn energy storage voltage difference is Vled.

[0231] Step (3): The fourth switch S4 and the fifth switch S5 of the second controller are simultaneously opened, and the third switch S3 and the sixth switch S6 are simultaneously closed, and the charging process of the second energy storage capacitor C12 in step (1) is repeated. At this time, the energy storage element Cn acts as the power output Vled to power the backlight control module.

[0232] Will Figure 37 and Figure 36 In comparison, using Figure 36 The power supply circuit shown requires the energy storage element Cn to be lower than Figure 37 The power supply circuit shown has low energy storage requirements and correspondingly low costs.

[0233] In some embodiments, Figure 32 The third voltage conversion module shown may be a flyback isolation module. Figure 38FIG. 1 is a schematic diagram of a power supply circuit structure of another display device according to an embodiment of the present application. Figure 38 As shown, the third voltage conversion module includes a flyback isolation transformer module. The flyback isolation transformer module is configured to superimpose the superimposed voltage generated by the secondary winding on the DC input voltage when the primary winding is turned off, and output the superimposed ninth voltage to the backlight control module. A first end of an energy storage element is connected to the output end of the flyback isolation transformer module. The energy storage element is configured to store the superimposed voltage when the primary winding is turned off, and superimpose the superimposed voltage on the DC input voltage when the primary winding is turned on, and output the superimposed ninth voltage to the backlight control module. The feedback signal is configured to instruct the flyback isolation transformer module to adjust the ninth voltage by adjusting the superimposed voltage.

[0234] Specifically, the voltage conversion module of the flyback isolation type adopted in this embodiment is electrically isolated through the primary winding and the secondary winding, which can better complete the voltage superposition. "Flyback" specifically means that when the switch tube is turned on, the secondary winding transformer acts as an inductor, and the electrical energy is converted into magnetic energy. At this time, there is no current in the output circuit; on the contrary, when the switch tube is turned off, the secondary winding transformer releases energy, and the magnetic energy is converted into electrical energy, and there is current in the output circuit. In the flyback voltage conversion module, the secondary winding transformer also acts as an energy storage inductor, which has the characteristics of few components, simple circuit, low cost, small size, etc. At the same time, electrical isolation improves the safety of use.

[0235] In some embodiments, Figure 38 The energy storage element shown can be a single energy storage capacitor or other energy storage circuit. The energy storage element cooperates with the flyback isolation transformer module to alternately output the ninth voltage to continuously power the backlight control module and make the light emitting diode emit light stably.

[0236] The power supply principle of the third voltage conversion module and the energy storage element is described below in conjunction with a specific circuit structure diagram of the flyback isolation transformer module and the energy storage element.

[0237] In some embodiments, Figure 39 Schematic diagram of a power supply circuit structure of a flyback isolation transformer module according to an embodiment of the present application. The flyback isolation transformer module includes: a primary winding, a secondary winding, a third diode D13, a third controller, and a seventh switch S7.

[0238] A first end of the primary winding is connected to a DC input voltage Vin, a second end of the primary winding is connected to a first end of a seventh switch S7, and a second end of the seventh switch S7 is grounded; a secondary winding is coupled to the primary winding, a first end of the secondary winding is connected to the anode of a third diode D13, and a second end of the secondary winding is connected to the DC input voltage Vin; a cathode of the third diode D13 serves as an output end of the flyback isolation transformer module, outputting a ninth voltage Vled.

[0239] The third controller is connected with the control end of the seventh switch S7, and is used for controlling the conduction and cut-off of the primary winding to adjust the superimposed voltage by controlling the switching frequency of the seventh switch S7 according to the feedback signal.

[0240] The second end of the secondary winding is connected with the DC input voltage Vin, that is, the DC input voltage Vin is applied to the second end of the secondary winding. In some embodiments, the DC input voltage Vin applied to the second end of the secondary winding can be realized by establishing a physical connection between the second end of the secondary winding and the first end of the primary winding. In some embodiments, the DC input voltage Vin applied to the second end of the secondary winding can also be realized by establishing a physical connection between the second end of the secondary winding and the power supply interface, which is more conducive to realizing electrical isolation.

[0241] Based on the power supply circuit shown in FIG. 8, the principle of the third voltage conversion module cooperating with the energy storage element to supply power is as follows: Figure 39

[0242] Step (1): The third controller controls the seventh switch S7 to be turned on, the primary winding is turned on, the current in the primary winding increases linearly, and the inductive energy storage increases; the third diode D13 is not turned on, and the secondary winding is not turned on. The switching frequency of the seventh switch S7 can be controlled to control the energy storage voltage of the primary winding.

[0243] Step (2): The third controller controls the seventh switch S7 to be turned off, the primary winding is cut off, and the current in the primary winding is cut off; the third diode D13 is turned on, and the secondary winding is turned on. By setting the turns ratio of the primary winding and the secondary winding, the secondary winding can generate a superimposed voltage Vo; at the same time, since the second end of the secondary winding is connected with the DC input voltage Vin, after voltage superposition, the first end of the secondary winding outputs a superimposed ninth voltage Vled, where Vled=Vin+Vo. At this time, for the energy storage element Cn, the first end is connected with the voltage Vled, and the second end is connected with the voltage Vin, therefore, the energy storage element Cn is charged, and the energy storage pressure difference of Cn is Vo.

[0244] Step (3): The third controller controls the seventh switch S7 to be turned on, and the energy storage process of the primary winding is repeated in step (1). At the same time, regarding the energy storage element Cn as a battery with the upper end (i.e. the first end) being the positive electrode and the lower end (i.e. the second end) being the negative electrode, connecting the DC input voltage Vin to the second end of the energy storage element Cn is equivalent to connecting two power supplies in series, that is, voltage superposition is performed. Therefore, the superimposed ninth voltage Vled is output through the first end of the energy storage element Cn.

[0245] For the power supply circuit shown in FIG. 8, the principle of the third voltage conversion module cooperating with the energy storage element to supply power is as follows: Figure 39 ​The power supply circuit shown only needs to control the size of the superimposed voltage Vo to control the change of the ninth voltage Vled. The third controller controls the number of charge transmission by controlling the switching frequency or duty cycle of the seventh switch S7 based on the feedback signal, thereby achieving the purpose of controlling the ninth voltage Vled. The direct current input voltage Vin is relatively stable, which is equivalent to a "fixed voltage"; the superimposed voltage Vo is equivalent to a "variable voltage". Since the direct current input voltage Vin is relatively stable, the output voltage change range of the superimposed voltage Vo depends on the required change range of the ninth voltage Vled. The above-mentioned circuit structure of superimposing a "fixed voltage" with a "variable voltage" is a "step power supply", which can achieve the purposes of reducing cost and improving efficiency.

[0246] In some embodiments, Figure 39 In the power supply circuit shown, the second end of the energy storage element Cn can also be grounded. Figure 40 Another power supply circuit structure diagram of a flyback isolation transformer module according to an embodiment of the present application. Compared with Figure 39 The difference is that the second end of the energy storage element Cn is grounded. Therefore, Figure 40 Compared with Figure 39 The difference between the power supply principle is that the energy storage voltage difference of the energy storage element Cn is different.

[0247] Based on Figure 40 The power supply circuit shown, the third voltage conversion module cooperates with the energy storage element to supply power as follows:

[0248] Step (1): The third controller controls the seventh switch S7 to be turned on, the primary winding is turned on, the current in the primary winding increases linearly, and the inductance energy storage increases; the third diode D13 is not turned on, and the secondary winding is not turned on. By controlling the switching frequency of the seventh switch S7, the energy storage voltage of the primary winding can be controlled.

[0249] Step (2): The third controller controls the seventh switch S7 to be turned off, the primary winding is cut off, and the current in the primary winding is cut off; the third diode D13 is turned on, and the secondary winding is turned on. By setting the number of turns of the primary winding and the secondary winding, the secondary winding can generate a superimposed voltage Vo; at the same time, since the second end of the secondary winding is connected to the direct current input voltage Vin, after voltage superposition, the first end of the secondary winding outputs the superimposed ninth voltage Vled, where Vled=Vin+Vo. At this time, for the energy storage element Cn, the first end is connected to the voltage Vled, and the second end is connected to the voltage 0, therefore, the energy storage element Cn is charged, and the energy storage voltage difference of Cn is Vled.

[0250] Step (3): the third controller controls the seventh switch S7 to be on, and the energy storage process of the primary winding in step (1) is repeated. At this time, the energy storage element Cn is regarded as a battery with the upper end (i.e. the first end) being the positive electrode and the lower end (i.e. the second end) being the negative electrode, and the output Vled is used to supply power to the backlight control module.

[0251] Compared with the power supply circuit shown in Figure 40 , the power supply circuit shown in Figure 39 has lower energy storage requirements for the energy storage element Cn. Figure 39 The lower energy storage requirement corresponds to lower cost. Figure 39

[0252] In some embodiments, the display device provided by the embodiments further includes a first filtering module; the first filtering module is connected with the power supply interface and the third voltage conversion module, and is used for filtering the direct current input voltage. The first filtering module can be a filtering circuit composed of one or more grounding capacitors, or a filtering circuit composed of capacitors and inductors.

[0253] For example, Figure 41 , the structure of a filtering module according to an embodiment of the present application is shown in FIG. 13. The first filtering module takes a grounding capacitor as an example. Specifically, the direct current input voltage of the power supply interface and the ground are connected in parallel with the first filtering capacitor C13. The first filtering capacitor C13 is used for filtering the noise and alternating current components of the power supply, smoothing the pulsed direct current voltage, and storing electrical energy. The capacitance of the first filtering capacitor C13 is related to the load current and the purity of the power supply, and a larger-capacity filtering capacitor is usually selected.

[0254] In some embodiments, the first filtering capacitor C13 can be an electrolytic capacitor as shown in Figure 41 . The electrolytic capacitor is a type of capacitor, the metal foil is the positive electrode (aluminum or tantalum), the oxide film (aluminum oxide or tantalum pentoxide) closely attached to the positive electrode is the dielectric, and the cathode is composed of conductive materials, electrolytes (the electrolyte can be liquid or solid) and other materials. The main part of the cathode is the electrolyte. The capacitance per unit volume is very large. Since the preparation materials are ordinary industrial materials and the preparation process is ordinary industrial equipment, batch production can be carried out, so the cost is relatively low. It should be noted that the positive and negative electrodes of the electrolytic capacitor cannot be connected in reverse.

[0255] In some embodiments, the first filtering capacitor C13 can also be other types of capacitors, such as ceramic strip content capacitors, thin film capacitors, mica capacitors, etc. In actual circuits, the capacitors can be selected according to the capacitance requirements.

[0256] ​In some embodiments, the display device provided by the embodiments further comprises a second filtering module; the second filtering module is connected to the output end of the third voltage conversion module and is used for filtering the ninth voltage. The second filtering module can be a filtering circuit composed of one or more grounding capacitors or a filtering circuit composed of capacitors and inductors. As shown in Figure 41 , the second filtering capacitor C14 connected to the ground is taken as an example for filtering.

[0257] As shown in Figure 41 , the second end of the energy storage element Cn is connected to the direct current input voltage Vin. During power supply, the charge pump module or the flyback isolation transformer module cooperates with the energy storage element Cn to alternately output the ninth voltage Vled. The filtering module can also be arranged at the connection between the direct current input voltage Vin and the second end of the energy storage element Cn, which is used for filtering the noise in the direct current input voltage Vin input to the energy storage element Cn.

[0258] In some embodiments, the display device provided by the embodiments further comprises a fourth diode Dn; the positive electrode of the fourth diode Dn is connected to the second end of the energy storage element Cn, and the negative electrode of the fourth diode Dn is connected to the first end of the energy storage element Cn. The direct current input voltage Vin is input to the backlight control module by using the fourth diode Dn to form a current loop, which prevents the current from flowing through the third voltage conversion module when the third voltage conversion module is not working, thereby preventing system malfunction or other abnormal conditions and protecting the third voltage conversion module.

[0259] In some embodiments, Figure 42 , the structure schematic diagram of a filtering module based on a charge pump module power supply circuit according to the embodiments of the present application. The charge pump module takes Figure 36 as an example, and the power supply principle is not described again. In some embodiments, Figure 43 , the structure schematic diagram of a filtering module based on a flyback isolation transformer module power supply circuit according to the embodiments of the present application. The flyback isolation transformer module takes Figure 39 as an example, wherein the physical connection is established between the second end of the secondary winding and the first end of the primary winding to apply the direct current input voltage Vin to the second end of the secondary winding, and the power supply principle is not described again.

[0260] In some embodiments, the display device provided by the embodiments further comprises a mainboard; the mainboard is connected to the power supply interface, and the direct current input voltage is used for supplying power to the mainboard. Figure 44 , the third circuit structure schematic diagram for supplying power to the mainboard according to the embodiments of the present application. When the direct current input voltage is equal to the required voltage of the mainboard, the direct current input voltage can be selected to directly supply power to the mainboard.

[0261] In some embodiments, the display device provided by the embodiments further comprises a fourth voltage conversion module; the fourth voltage conversion module is connected with the power supply interface and the mainboard, and is configured to output a tenth voltage according to the direct current input voltage, the tenth voltage being a required voltage of the mainboard. Figure 45 A fourth circuit structure for supplying power to the mainboard according to the embodiments of the present application is shown in the figure. When the direct current input voltage does not meet the required voltage of the mainboard, the fourth voltage conversion module can be used to perform DC-DC voltage conversion on the direct current input voltage. When the television has a large power, in order to reduce the loss of the cable, the voltage is often increased and the current is reduced, so the direct current input voltage can be higher than the required voltage of the mainboard. In some embodiments, since the mainboard usually requires a fixed voltage, the fourth voltage conversion module can use a buck voltage reduction circuit, a boost-buck voltage increase and reduction circuit, etc.

[0262] The embodiments also provide a display control method applied to the display device described above, comprising: receiving a feedback signal, the feedback signal being generated by the backlight control module and sent through the feedback module; adjusting the superimposed voltage based on the feedback signal to adjust the ninth voltage; the ninth voltage being a required voltage of the backlight control module.

[0263] In the embodiments, the superimposed voltage generated by the third voltage conversion module is adjusted according to the feedback signal of the real-time current output by the backlight control module, and then the ninth voltage is adjusted, so that the backlight control module works at the rated current, preventing the damage of the components caused by the excessive current flowing through the LED components in the LED lamp string. The superimposed voltage is equivalent to the "variable voltage"; the tenth voltage is equivalent to the "fixed voltage", and the voltage superposition of the two achieves step power supply, which is beneficial to reduce the heat loss.

[0264] The display device according to the embodiments of the present application comprises: a backlight control module configured to control light-emitting diodes to emit light, the light-emitting diodes being configured to light up a screen of the display device; a power supply interface configured to receive a direct current input voltage, the direct current input voltage being provided by an external adapter; a third voltage conversion module configured to generate a superimposed voltage according to the direct current input voltage, and superimpose the superimposed voltage and the direct current input voltage to output a ninth voltage after superposition; the ninth voltage being a required voltage of the backlight control module; an energy storage element, a first end of the energy storage element being connected with an output end of the third voltage conversion module, and a second end of the energy storage element being connected with the direct current input voltage, the energy storage element being configured to store the superimposed voltage and alternately output the ninth voltage with the third voltage conversion module; and a feedback module configured to send a feedback signal generated by the backlight control module to the third voltage conversion module, the feedback signal being configured to instruct the third voltage conversion module to adjust the ninth voltage.

[0265] In the embodiment of the application, a power supply interface connected with an external adapter is arranged to receive a direct current input voltage to adapt to the power supply mode of the external adapter; the direct current input voltage is used to generate a superimposed voltage, and the superimposed voltage is superimposed with the direct current input voltage to realize step power supply, which is beneficial to reduce heat loss; the energy storage element is used to realize continuous power supply for the backlight control module; the power supply voltage of the backlight control module is adjusted in time through real-time feedback to stabilize the working of the light emitting diode.

[0266] It should be understood that the application is not limited to the precise construction which has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the application is limited only by the claims which follow.

Claims

1. A backlight control circuit, characterized in that: include: A transformer, comprising: a primary coil configured to receive power; a first secondary coil coupled to the primary coil, wherein a first output terminal of the first secondary coil is configured to output a first voltage, and a second output terminal of the first secondary coil is coupled to ground; a second secondary coil coupled to the primary coil, wherein the second secondary coil is configured to output a second voltage; a voltage conversion module, coupled to the first output terminal of the first secondary coil, the first output terminal of the second secondary coil, and the second output terminal of the second secondary coil, respectively, and configured to generate a superimposed voltage based on the first voltage, and superimpose the superimposed voltage on the second voltage to output a third voltage; wherein the voltage conversion module includes a first current sharing capacitor; A light string group includes a first light string and a second light string, wherein a first end of the first light string and a second end of the second light string are respectively coupled to the voltage conversion module; when the first current sharing capacitor is in a first state, the first light string is illuminated based on the third voltage, and the second light string is not illuminated; when the first current sharing capacitor is in a second state, the second light string is illuminated based on the third voltage, and the first light string is not illuminated; A feedback module is coupled to the second end of the light string group and the voltage conversion module respectively, and generates a feedback signal according to the output current of the light string group, so that the voltage conversion module adjusts the third voltage.

2. The backlight control circuit according to claim 1, wherein: The voltage conversion module includes: a voltage adjustment module, coupled to the first output terminal of the first secondary coil, and configured to generate a superimposed voltage according to the first voltage; A voltage superposition module is coupled to the first output end of the second secondary coil, the second output end of the second secondary coil, the first light string, the second light string and the voltage adjustment module, respectively, and is configured to superimpose the superimposed voltage on the second voltage and output the third voltage.

3. The backlight control circuit according to claim 2, wherein: 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 coupled to the first output end of the second secondary coil; the other end of the first current-sharing capacitor is coupled to the anode of the first rectifier diode and the cathode of the second rectifier diode respectively; the anode of the second rectifier diode is coupled to the superimposed voltage; the cathode of the first rectifier diode is coupled to the anode of the first light string; and the cathode of the first light string is grounded. The positive pole of the third rectifier diode is coupled to the second output end of the second secondary coil and the negative pole of the fourth rectifier diode respectively, and the positive pole of the fourth rectifier diode is coupled to the superimposed voltage; the negative pole of the third rectifier diode is coupled to the positive pole of the second light string; and the negative pole of the second light string is grounded.

4. The backlight control circuit 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 coupled to the first output end of the first secondary coil; the other end of the second transistor is coupled to one end of the third transistor and one end of the second inductor respectively; the other end of the third transistor is grounded; The other end of the second inductor serves as the output end of the voltage adjustment module to output the superimposed voltage; One end of the second capacitor is coupled to the other end of the second inductor; the other end of the second capacitor is grounded; The control electrode of the second transistor and the control electrode of the third transistor are both coupled to the feedback module and are configured to adjust the switching frequency of the second transistor and the third transistor according to the feedback signal to adjust the superimposed voltage.

5. The backlight control circuit according to claim 4, wherein: The voltage adjustment module further includes a second diode; The cathode of the second diode is coupled to one end of the second capacitor; the anode of the second diode is coupled to the other end of the second capacitor, and the second diode is used to reduce the loss of the third transistor.

6. The backlight control circuit according to claim 1, wherein: Also includes: a first switching circuit and a first grounding resistor; The first switch circuit is located between the light string group and the first grounding resistor; One end of the first switching circuit is coupled to the negative pole of the first light string and the negative pole of the second light string respectively, and the other end of the first switching circuit is coupled to one end of the first grounding resistor and the input end of the feedback module respectively; the other end of the first grounding resistor is grounded; the first switching circuit is configured to be turned on or off based on a duty cycle control signal.

7. The backlight control circuit according to claim 1, wherein: Also includes: a second switching circuit and a second grounding resistor; The second switch circuit is located between the light string group and the second grounding resistor; One end of the second switch circuit is coupled to the negative electrode of the first light string and the negative electrode of the second light string respectively, and the other end of the second switch circuit is coupled to one end of the second grounding resistor; the other end of the second grounding resistor is grounded; The second switching circuit is configured to change the loop current to perform analog dimming.

8. The backlight control circuit according to claim 7, wherein: The second switch circuit includes: a fifth transistor and a comparator; One end of the fifth transistor is coupled to the cathode of the first light string and the cathode of the second light string respectively; the other end of the fifth transistor is coupled to one end of the second grounding resistor and the inverting input end of the comparator respectively; The non-inverting input terminal of the comparator is configured to input the required voltage of the light string group, and the output terminal of the comparator is coupled to the gate of the fifth transistor; The fifth transistor is configured to change the loop current by adjusting the resistance of the fifth transistor to perform analog dimming.

9. The backlight control circuit according to claim 2, wherein: The voltage adjustment module includes: a first inductor, a first transistor, a first diode, and a first capacitor; one end of the first inductor is coupled to the first output end of the first secondary coil; the other end of the first inductor is respectively coupled to one end of the first transistor and the positive electrode of the first diode; the other end of the first transistor is grounded; the negative electrode of the first diode serves as the output end of the voltage adjustment module to output the superimposed voltage; one end of the first capacitor is coupled to the negative electrode of the first diode; the other end of the first capacitor is grounded; the control electrode of the first transistor is coupled to the feedback module, and is used to adjust the switching frequency of the first transistor according to the feedback signal to adjust the superimposed voltage.

10. The backlight control circuit according to claim 1, wherein: include: The number of the second secondary coil, the voltage conversion module and the light string group is multiple; The backlight control circuit further includes a plurality of current-sharing inductors; The mutually coupled current-sharing inductor is provided between two adjacent second secondary coils.

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