Area-based brightness adjustment method and related device

Abstract

The application discloses a regional light control brightness adjusting method and related device. The method comprises the following steps: acquiring a first list, wherein the first list comprises different average picture brightness values and corresponding demand brightness values, the demand brightness values are preset brightness values according to demands; obtaining a second list according to the first list, wherein the second list comprises different average picture brightness values and corresponding first duty cycle values; obtaining a first relationship according to the second list; reading target average picture brightness values of each frame in a video signal when playing the video; obtaining a target duty cycle value according to the first relationship and the target average picture brightness values, and outputting a PWM signal corresponding to the target duty cycle value to adjust the brightness of the backlight module.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to a method and related apparatus for adjusting the brightness of a local area of ​​light. Background Technology

[0002] With the continuous development of society and the gradual maturation of display-related technologies, displays have become widespread in various fields, such as commercial media, cultural performance market, sports venues, information dissemination, news release, and securities trading, bringing convenience to people's production and life.

[0003] To improve the display effect of current Mini-LED displays, local dimming function has emerged. The function of local dimming is to turn on the backlight of the corresponding zone in the area that needs to be displayed as bright, and turn off the backlight of the corresponding zone in the area that needs to be displayed as dark, thus improving the display effect and contrast.

[0004] However, the above method has a problem: due to differences in human sensitivity to brightness, even if the brightness of each zone remains constant under different lighting ratios, users will perceive the brightness of the zones as fluctuating. Therefore, the brightness of each zone needs to be adjusted according to different lighting ratios.

[0005] This is usually achieved by adjusting the current, but it has been found that adjusting the current can cause the backlight to flicker on certain screens. Summary of the Invention

[0006] This application provides a method and related apparatus for adjusting the brightness of a specific area of ​​light.

[0007] A method for adjusting brightness in a local dimming area, used in a backlight module, includes the following steps:

[0008] Obtain a first list, which includes different average screen brightness values ​​and corresponding required brightness values, wherein the required brightness values ​​are preset brightness values ​​according to requirements;

[0009] A second list is obtained based on the first list, and the second list includes different average screen brightness values ​​and corresponding first duty cycle values.

[0010] The first relation is obtained from the second list;

[0011] When playing a video, read the target average screen brightness value of each frame in the video signal;

[0012] Based on the first relational expression and the target average screen brightness value, the target duty cycle value is obtained, and a PWM signal corresponding to the target duty cycle value is output to adjust the brightness of the backlight module.

[0013] Optionally, obtaining the second list based on the first list includes the following steps:

[0014] Obtain the required brightness value and the peak brightness value of the backlight module under different average screen brightness in the first list, wherein the peak brightness value is the measured maximum brightness value of the backlight module;

[0015] Calculate a first ratio between the required brightness value and the peak brightness value, and use the first ratio as the first duty cycle value.

[0016] Optionally, obtaining the second list based on the first list includes the following steps:

[0017] Obtain the peak current value of the backlight module, wherein the peak current value is the maximum rated current value of the backlight module;

[0018] Calculate the corresponding required current value based on the required brightness value;

[0019] Calculate a second ratio between the required current value and the peak current value, and use the second ratio as the first duty cycle value.

[0020] Optionally, before obtaining the first list, the method further includes the following steps:

[0021] The backlight module is controlled to play a preset white field image, which is a number of images with black edges and white centers;

[0022] The proportion of white portion to the entire image in the white field image is used as the average image brightness value;

[0023] Adjust the brightness of the backlight module to obtain the required brightness value;

[0024] The average screen brightness value and the required brightness value are recorded as the first list.

[0025] Optionally, adjusting the brightness of the backlight module to obtain the required brightness value includes the following steps:

[0026] Adjust the brightness of the backlight module to obtain multiple subjective brightness values ​​input by the user;

[0027] The average of the multiple subjective brightness values ​​is taken as the required brightness value.

[0028] Optionally, obtaining the first relation based on the second list includes the following steps:

[0029] Take an average screen brightness value and its corresponding first duty cycle value as a data pair, obtain all data pairs in the second list, select all or part of the data pairs, and use the selected data pairs to obtain the first relational expression.

[0030] Optionally, selecting all or part of the data pairs includes the following steps:

[0031] When the number of data pairs in the second list is less than or equal to the preset number, all data pairs are selected;

[0032] or,

[0033] When the number of data pairs in the second list is greater than the preset number, first select the data pair containing the maximum first duty cycle value and the minimum first duty cycle value; then select the required data pairs by interval selection or random selection until the number of selected data pairs is the preset number.

[0034] or,

[0035] When the number of data pairs in the second list is greater than the preset number, the required data pairs are selected at intervals or randomly until the number of selected data pairs is the preset number.

[0036] Optionally, obtaining the first relation using the selected data pair includes the following steps:

[0037] Based on the selected data pairs, construct a polynomial relationship of the corresponding power to obtain the coefficients of the polynomial relationship and thus obtain the first relation.

[0038] Optionally, the step of constructing a polynomial relationship of corresponding powers based on the selected data pairs includes:

[0039] The power is half the number of data pairs, the number of selected data pairs is 8 to 12, and the power is 4 to 6.

[0040] The process of obtaining the coefficients of the polynomial relation includes:

[0041] The coefficients of the polynomial relationship are obtained by calculating the polynomial regression equation.

[0042] A local dimming brightness adjustment device, employing the method described above, includes:

[0043] The receiving end receives the video signal and reads the target average screen brightness value of each frame in the video signal;

[0044] The computing storage terminal stores the first relational formula and calculates and outputs the target duty cycle value based on the target average screen brightness value provided by the receiving terminal.

[0045] The drive output terminal receives the target duty cycle value provided by the computing and storage terminal and outputs a PWM drive signal corresponding to the target duty cycle value.

[0046] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0047] A first list is obtained, and a second list is derived from it. Then, a first relational expression is obtained from the second list. After reading the target average screen brightness value, the target duty cycle value is obtained based on the first relational expression and the target average screen brightness value. Brightness is then adjusted according to the target duty cycle value. Compared to adjusting backlight brightness by changing the current, this invention achieves more subtle changes, smooth backlight changes at any brightness level, and eliminates visible brightness variations and backlight flickering during playback. Since it does not use current adjustment, there is no need to select a suitable sense resistor, thus avoiding complex selection issues and making it convenient to use. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of an embodiment of the area control brightness adjustment method of this application;

[0049] Figure 2 This is a schematic diagram of another embodiment of the area control brightness adjustment method of this application;

[0050] Figure 3 This is a white field image and a schematic diagram of the LED effect in this application;

[0051] Figure 4 This is a schematic diagram of the average screen brightness value versus duty cycle value in this application;

[0052] Figure 5 This is a schematic diagram of an embodiment of the area-controlled light brightness adjustment device of this application;

[0053] Figure 6 This is a schematic diagram of another embodiment of the area control brightness adjustment device of this application. Detailed Implementation

[0054] This application provides a method and related apparatus for adjusting the brightness of a specific area of ​​light.

[0055] Existing methods that adjust the backlight module's brightness by regulating the voltage and thus the current suffer from uneven brightness changes. This is because the resistance at the driver board remains essentially constant, meaning the current change is limited by the resistance, resulting in uneven brightness variations and backlight flickering on certain screen displays. Furthermore, selecting the appropriate resistors requires significant time and manpower. This application provides a local dimming brightness adjustment method and related apparatus that enables smoother brightness adjustment of the backlight module, thus providing a better user experience.

[0056] The regional light control brightness adjustment method of this application is described below. Please refer to... Figure 1 An embodiment of the regional light control brightness adjustment method of this application, used in a backlight module, includes:

[0057] 101. Retrieve the first list;

[0058] The system retrieves a first list, which includes different average picture brightness values ​​and their corresponding required brightness values. The required brightness value is a preset brightness value based on demand. Specifically, the average picture brightness (APL) indicates how much of the image displayed on the screen is bright and how much is dark, and is described in a form similar to "screen ratio." For example, when the white portion of a white image is one-quarter of the total image size, it simulates 25% APL; half a screen is 50% APL; and a full white screen is 100% APL. The required brightness value is a brightness value that needs to be experimentally measured in advance to ensure smooth brightness changes in the module. This subjective brightness value is obtained through the subjective judgment of multiple optoelectronic engineers, and the average of these subjective brightness values ​​is then calculated to arrive at the required brightness value.

[0059] 102. Obtain the second list based on the first list;

[0060] A second list is obtained from the first list, which includes different average screen brightness values ​​and their corresponding first duty cycle values. Specifically, the required brightness value and the peak brightness value of the backlight module under different average screen brightness levels in the first list can be obtained first. Then, the first ratio of the required brightness value and the peak brightness value can be calculated, and this first ratio is used as the first duty cycle value. The peak brightness value is the measured maximum brightness value of the backlight module. For example, if the required brightness value at 10% APL is 1080 nits and the peak brightness value is 1200 nits, then the first duty cycle value is 1080 / 1200 = 0.9.

[0061] Specifically, the peak current value of the backlight module can be obtained first, then the corresponding required current value can be calculated based on the required brightness value, and finally the second ratio of the required current value to the peak current value can be calculated, which is then used as the first duty cycle value. The peak current value is the maximum rated current value of the backlight module.

[0062] 103. Obtain the first relation based on the second list;

[0063] The first relational expression is obtained from the second list. Specifically, an average screen brightness value and its corresponding first duty cycle value are treated as a data pair. All data pairs in the second list are retrieved, and all or some data pairs are selected. The selected data pairs are then used to obtain the first relational expression. The selection of data pairs can be determined according to the actual situation. The first relational expression represents the mathematical relationship between the average screen brightness value and the duty cycle value of the backlight module. It can be a univariate polynomial equation or a multivariate polynomial equation; the specific relationship is not limited here.

[0064] 104. When playing a video, read the average brightness value of the target image in each frame of the video signal;

[0065] When playing a video, the target average screen brightness value of each frame in the video signal is read. The target average screen brightness value is the average screen brightness value that the backlight module will display next.

[0066] 105. Based on the first relational formula and the target average screen brightness value, obtain the target duty cycle value, and output the PWM signal corresponding to the target duty cycle value to adjust the brightness of the backlight module.

[0067] Based on the first relational expression and the target average screen brightness value, the target duty cycle value is obtained, and a PWM signal corresponding to the target duty cycle value is output to adjust the brightness of the backlight module. Specifically, the target average screen brightness value is substituted into the first relational expression to obtain the target duty cycle value, which is then used to adjust the brightness of the backlight module. Furthermore, the effective number of bits for the module's duty cycle is at least 13 bits, resulting in a duty cycle range of 0-4095, a relatively large variation range, which ensures smooth brightness changes during adjustment.

[0068] In this embodiment, a first list is obtained, a second list is generated based on the first list, and then a first relational expression is derived from the second list. After reading the target average screen brightness value, the target duty cycle value is obtained based on the first relational expression and the target average screen brightness value, and the brightness is adjusted according to the target duty cycle value. Compared with adjusting the backlight brightness by changing the current, this invention achieves more subtle changes, smooth backlight changes at any brightness level, and no visible changes in brightness or flickering during playback. Since it does not use current adjustment, there is no need to select a suitable sense resistor, eliminating the complicated selection process and making it convenient to use.

[0069] Please see Figure 2 Another embodiment of the regional light control brightness adjustment method of this application, used in a backlight module, includes:

[0070] 201. Control the backlight module to play a preset white field image;

[0071] Control the backlight module to play preset white field images. These white field images consist of several images with black edges and white centers, such as... Figure 3 As shown. The white portion can be adjusted according to actual needs; no specific restrictions are specified here.

[0072] 202. The proportion of white areas in a white-field image to the entire image is used as the average image brightness value;

[0073] The average screen brightness (APL) is calculated by taking the proportion of white space in the white area of ​​the image. For example, when the white area in the white area is one-quarter of the total image size, it simulates 25% APL; half a screen is 50% APL; and a full white screen is 100% APL.

[0074] 203. Adjust the brightness of the backlight module to obtain multiple subjective brightness values ​​input by the user;

[0075] The brightness of the backlight module is adjusted to obtain multiple subjective brightness values ​​input by the user. Specifically, the brightness of the backlight module is adjusted, and multiple optoelectronic engineers subjectively determine the smoothest brightness value under different average screen brightness values, thus obtaining multiple subjective brightness values.

[0076] 204. Use the average of multiple subjective brightness values ​​as the required brightness value;

[0077] The required brightness value is obtained by averaging multiple subjective brightness values. Specifically, the required brightness value is obtained by averaging multiple subjective brightness values. Alternatively, it can be obtained using algorithms such as weighted averaging, which can be set according to actual needs; no specific limitation is made here.

[0078] 205. Record the average screen brightness value and the required brightness value as the first list;

[0079] Record the average screen brightness value and the required brightness value as a primary list. Specifically, record the different average screen brightness values ​​and their corresponding required brightness values ​​as a primary list for subsequent operations.

[0080] 206. Retrieve the first list;

[0081] Obtain the first list, which includes different average screen brightness values ​​and corresponding required brightness values. The required brightness values ​​are the brightness values ​​that need to be experimentally measured in advance to make the brightness change of the module smooth.

[0082] 207. Obtain the second list based on the first list;

[0083] A second list is obtained from the first list, which includes different average screen brightness values ​​and their corresponding first duty cycle values. Specifically, the required brightness value and the peak brightness value of the backlight module under different average screen brightness levels in the first list can be obtained first. Then, the first ratio of the required brightness value and the peak brightness value can be calculated, and this first ratio is used as the first duty cycle value. The peak brightness value is the measured maximum brightness value of the backlight module. For example, if the required brightness value at 10% APL is 1080 nits and the peak brightness value is 1200 nits, then the first duty cycle value is 1080 / 1200 = 0.9.

[0084] Specifically, the peak current value of the backlight module can be obtained first, then the corresponding required current value can be calculated based on the required brightness value, and finally the second ratio of the required current value to the peak current value can be calculated, which is then used as the first duty cycle value. The peak current value is the maximum rated current value of the backlight module.

[0085] 208. Take an average screen brightness value and its corresponding first duty cycle value as a data pair, obtain all data pairs in the second list, select all or part of the data pairs, and use the selected data pairs to obtain the first relational expression;

[0086] Retrieve data pairs from the second list, select all or part of them, and then use the selected data pairs to obtain the first relation. Specifically, there are three cases for selecting data pairs: when the number of data pairs in the second list is less than or equal to a preset number, select all data pairs; or, when the number of data pairs in the second list is greater than the preset number, first select the data pairs containing the largest and smallest first duty cycles, and then use interval selection or random selection of the required data pairs until the number of selected data pairs is the preset number; or, when the number of data pairs in the second list is greater than the preset number, use interval selection or random selection of the required data pairs until the number of selected data pairs is the preset number. The preset number can be set according to actual needs and is not limited here.

[0087] Based on the number of selected data pairs, a polynomial relation of corresponding powers is constructed to obtain the coefficients of the polynomial relation, thus yielding the first relation. Generally, the power can be half the number of data pairs, the number of selected data pairs can be 8 to 12, and the power can be 4 to 6. An example of the first relation is as follows:

[0088] y = a * x 5 +b*x 4 +c*x 3 +d*x 2 +e*x+f;

[0089] Where y is the duty cycle;

[0090] x represents the average screen brightness;

[0091] a, b, c, d, e, and f are the constant coefficients of the formula, i.e., the coefficients of the polynomial relationship, which have been obtained in the above steps.

[0092] like Figure 4 As shown, the solid line represents the mathematical relationship between the average image brightness and the corresponding duty cycle coefficient in the prior art, while the dashed curve represents the first relationship. It can be seen that the dashed line is smoother than the solid line, so the final brightness adjustment can be smoother.

[0093] 209. When playing a video, read the average brightness value of the target image in each frame of the video signal;

[0094] When playing a video, the target average screen brightness value of each frame in the video signal is read. The target average screen brightness value is the average screen brightness value that the backlight module will display next.

[0095] 210. Based on the first relational expression and the target average screen brightness value, obtain the target duty cycle value, and output the PWM signal corresponding to the target duty cycle value to adjust the brightness of the backlight module.

[0096] Based on the first relational expression and the target average screen brightness value, the target duty cycle value is obtained, and a PWM signal corresponding to the target duty cycle value is output to adjust the brightness of the backlight module. Specifically, the target average screen brightness value is substituted into the first relational expression to obtain the target duty cycle value, which is then used to adjust the brightness of the backlight module. Furthermore, the effective number of bits for the module's duty cycle is at least 13 bits, resulting in a duty cycle range of 0-4095, a relatively large variation range, which ensures smooth brightness changes during adjustment.

[0097] In this embodiment, a first list is obtained, a second list is generated based on the first list, and then a first relational expression is derived from the second list. After reading the target average screen brightness value, the target duty cycle value is obtained based on the first relational expression and the target average screen brightness value, and the brightness is adjusted according to the target duty cycle value. Compared with adjusting the backlight brightness by changing the current, this invention achieves more subtle changes, smooth backlight changes at any brightness level, and no visible bright / dark changes or backlight flickering issues during playback. Since it does not use current adjustment, there is no need to select a suitable sense resistor, eliminating the complicated selection process and making it convenient to use.

[0098] The area-controlled brightness adjustment device of this application is described below. Please refer to... Figure 5 One embodiment of the area-controlled brightness adjustment device of this application includes:

[0099] Receiver 501 receives video signals and reads the target average screen brightness value of each frame in the video signal;

[0100] The calculation storage terminal 502 stores the first relational formula and calculates and outputs the target duty cycle value based on the target average screen brightness value provided by the receiving terminal.

[0101] The drive output terminal 503 receives the target duty cycle value provided by the calculation and storage terminal and outputs a PWM drive signal corresponding to the target duty cycle value.

[0102] In this embodiment, the receiving end 501 receives a video signal, reads the target average screen brightness value of each frame in the video signal, then calculates and stores the first relational formula in the storage end 502, and calculates and outputs the target duty cycle value based on the target average screen brightness value. Finally, the driving output end 503 receives the target duty cycle value and outputs a PWM driving signal corresponding to the target duty cycle value. Compared with the method of adjusting the backlight brightness by changing the current, this invention can achieve more subtle changes, smooth backlight changes at any brightness, and no visible changes in brightness or flickering during playback. Since it does not use the method of adjusting the current, there is no need to select a suitable sense resistor, thus eliminating the complicated selection problem and making it convenient to use.

[0103] The functions and processes performed by each unit in the local dimming brightness adjustment device of this embodiment are the same as those described above. Figures 1 to 4 The functions and processes performed by the central area control brightness adjustment device are similar, and will not be described in detail here.

[0104] Figure 6This is a schematic diagram of a local light control brightness adjustment device provided in an embodiment of this application. The local light control brightness adjustment device 600 may include one or more central processing units (CPUs) 601 and a memory 605, in which one or more application programs or data are stored.

[0105] The memory 605 can be volatile or persistent storage. The program stored in the memory 605 can include one or more modules, each module including a series of instruction operations on the local dimming brightness adjustment device. Furthermore, the central processing unit 601 can be configured to communicate with the memory 605 and execute the series of instruction operations in the memory 605 on the local dimming brightness adjustment device 600.

[0106] The zonal brightness adjustment device 600 may also include one or more power supplies 602, one or more wired or wireless network interfaces 603, one or more input / output interfaces 604, and / or one or more operating systems, such as Windows Server™, MacOSX™, Unix™, Linux™, FreeBSD™, etc.

[0107] The central processing unit 601 can perform the aforementioned... Figures 1 to 4 The specific operations performed by the area control brightness adjustment device in the illustrated embodiment will not be described in detail here.

[0108] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0109] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0110] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0111] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0112] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for adjusting brightness in a specific area, used in a backlight module, characterized in that, Includes the following steps: Obtain a first list, which includes different average screen brightness values ​​and corresponding required brightness values, wherein the required brightness values ​​are preset brightness values ​​according to requirements; The first list generation step includes: controlling the backlight module to play a preset white field image, wherein the white field image is a plurality of images with black edges and white center; taking the proportion of white part in the white field image to the whole image as the average screen brightness value; adjusting the brightness of the backlight module to obtain the required brightness value; and recording the average screen brightness value and the required brightness value as the first list. A second list is obtained based on the first list, and the second list includes different average screen brightness values ​​and corresponding first duty cycle values. Obtaining the first relational expression based on the second list includes: taking an average screen brightness value and its corresponding first duty cycle value as a data pair, obtaining all data pairs in the second list, selecting all or part of the data pairs, constructing a polynomial relation of the corresponding power based on the number of selected data pairs, obtaining the coefficients of the polynomial relation, and obtaining the first relational expression. When playing a video, read the target average screen brightness value of each frame in the video signal; Based on the first relational expression and the target average screen brightness value, the target duty cycle value is obtained, and a PWM signal corresponding to the target duty cycle value is output to adjust the brightness of the backlight module.

2. The regional light control brightness adjustment method according to claim 1, characterized in that, The step of obtaining the second list based on the first list includes the following steps: Obtain the required brightness value and the peak brightness value of the backlight module under different average screen brightness in the first list, wherein the peak brightness value is the measured maximum brightness value of the backlight module; Calculate a first ratio between the required brightness value and the peak brightness value, and use the first ratio as the first duty cycle value.

3. The regional light control brightness adjustment method according to claim 1, characterized in that, The step of obtaining the second list based on the first list includes the following steps: Obtain the peak current value of the backlight module, wherein the peak current value is the maximum rated current value of the backlight module; Calculate the corresponding required current value based on the required brightness value; Calculate a second ratio between the required current value and the peak current value, and use the second ratio as the first duty cycle value.

4. The method for adjusting the brightness of regional light control according to claim 1, characterized in that, Adjusting the brightness of the backlight module to obtain the required brightness value includes the following steps: Adjust the brightness of the backlight module to obtain multiple subjective brightness values ​​input by the user; The average of the multiple subjective brightness values ​​is taken as the required brightness value.

5. The method for adjusting the brightness of regional light control according to claim 1, characterized in that, The selection of all or part of the data pairs includes the following steps: When the number of data pairs in the second list is less than or equal to the preset number, all data pairs are selected; or, When the number of data pairs in the second list is greater than the preset number, first select the data pair containing the maximum first duty cycle value and the minimum first duty cycle value; then select the required data pairs by interval selection or random selection until the number of selected data pairs is the preset number. or, When the number of data pairs in the second list is greater than the preset number, the required data pairs are selected at intervals or randomly until the number of selected data pairs is the preset number.

6. The method for adjusting the brightness of a region-controlled light source according to claim 1, characterized in that, The step of constructing a polynomial relationship of corresponding powers based on the selected data pairs includes: The power is half the number of data pairs, the number of selected data pairs is 8 to 12, and the power is 4 to 6. The process of obtaining the coefficients of the polynomial relation includes: The coefficients of the polynomial relationship are obtained by calculating the polynomial regression equation.

7. A regional light control brightness adjustment device, characterized in that, The method described in any one of claims 1 to 6, comprising: The receiving end receives the video signal and reads the target average screen brightness value of each frame in the video signal; The computing storage terminal stores the first relational formula and calculates and outputs the target duty cycle value based on the target average screen brightness value provided by the receiving terminal. The drive output terminal receives the target duty cycle value provided by the computing and storage terminal and outputs a PWM drive signal corresponding to the target duty cycle value.

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