Screen anti-burning protection method and device for advertisement display equipment and medium

Abstract

The invention discloses a screen anti-burning protection method and device for an advertisement display device and a medium, and the method comprises the steps: calculating a risk score through obtaining the state data of an advertisement screen, adding an anti-burning view to a covering layer between a main application and a system window when the screen is in a long-time static risk and exceeds a threshold value, and executing periodic pixel refreshing corresponding to the risk, and terminating and removing the view when the user inputs. According to the screen anti-burning protection method and device for the advertisement display equipment and the medium, a protection mechanism is accurately triggered through risk scores, an anti-burning view and main content are isolated through a covering layer, a periodic pixel refreshing mode is dynamically matched in combination with risk levels, refreshing is immediately stopped when user input is detected, and the user experience is improved. Therefore, while the ghost burn is effectively protected, the interference to the watching experience of the user is avoided, and the problem that the ghost burn protection of the advertisement screen is difficult to effectively realize in the prior art on the premise of ensuring the normal watching experience of the user can be solved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a method, device, and medium for screen burn-in protection of advertising display devices. Background Technology

[0002] In advertising displays or information display terminals, these devices often need to continuously play fixed content, such as attractive advertisements or eye-catching logos, 24 / 7. However, this prolonged static display mode poses potential risks to the screen, especially when using OLED or LCD display panels. Because pixels remain in the same state for extended periods, pixel aging and image retention issues can easily occur. These problems not only affect the display quality and reduce the efficiency of advertising or information delivery but may also shorten the lifespan of the advertising display device. Current screen burn-in prevention technologies primarily focus on reducing pixel aging caused by prolonged static display through methods such as optimizing display algorithms, adopting dynamic screen protection modes, implementing pixel shifting technology, and utilizing intelligent monitoring and adjustment systems. The aim is to prevent burn-in and image retention, thereby extending the lifespan of the advertising display device and maintaining a high-quality display effect.

[0003] However, for screen burn-in prevention technology, dynamic protection mechanisms are prone to triggering redundant operations when users pause briefly due to the difficulty of balancing trigger threshold sensitivity and visual interference. Pixel shifting technology is limited by screen size and displacement amplitude; small displacements are difficult to effectively distribute pixel load, while large shifts can easily cause visually perceptible screen jitter. When intelligent monitoring systems simultaneously track user gaze behavior and static screen elements, the lack of real-time performance and accuracy often leads to delayed or over-activated protection strategies. These technical limitations make it difficult for burn-in prevention mechanisms to achieve a dynamic balance with the screen stability required for high-precision display scenarios, ultimately making it difficult to achieve both the goal of preventing image retention and a seamless user experience. Summary of the Invention

[0004] This invention provides a method, device, and medium for screen burn-in protection of advertising display devices, in order to solve the problem that existing technologies are unable to effectively prevent burn-in and image retention on advertising screens while ensuring a normal viewing experience for users.

[0005] To achieve the above objectives, this application provides a screen burn-in protection method for advertising display devices, comprising:

[0006] Acquire screen status data of advertising display devices and calculate risk scores based on a preset weighting method;

[0007] When the risk score indicates that the screen of the advertising display device is in a long-term static risk and the duration exceeds a first threshold, an anti-burn-in view is added to the overlay located between the main application window and the system-level window.

[0008] A pixel refresh mode corresponding to the risk score is executed on the anti-burn-in view; wherein the pixel refresh mode is at least one periodic pixel refresh scheme;

[0009] When a user input signal is detected, the pixel refresh mode is terminated and the anti-burn-in view is removed.

[0010] This invention utilizes screen status data and a pre-calculated weighted risk score to activate protection only when the screen is under prolonged static risk exceeding a first threshold. This dynamic risk-level-based judgment avoids the interference of fixed-time forced refreshes on normal display, allowing intervention only when truly needed to ensure continuous viewing for the user. The protected view is attached as an overlay between the main application window and the system-level window, neither obscuring the main application content viewed by the user nor hindering burn-in prevention through the overlay. This layered design physically isolates the protection behavior from the core content viewed by the user, resolving the conflict between protection and obscuring the main screen. The pixel refresh mode corresponds to the risk score and employs a periodic pixel refresh scheme. A more efficient refresh mode is activated when the risk is high, while a lightweight mode is used when the risk is low. This dynamic adaptation avoids screen flickering or distortion caused by excessive refresh, effectively mitigating burn-in while minimizing the impact on the user's viewing experience. When a user input signal is detected, the refresh is immediately terminated and the burn-in prevention view is removed, preventing the protection behavior from interfering with user interaction with the device and further balancing protection needs with user experience.

[0011] Compared to existing technologies, this invention uses risk scores to accurately trigger a protection mechanism, utilizes an overlay layer to isolate the anti-burn-in view from the main content, dynamically matches the periodic pixel refresh mode with the risk level, and immediately stops refreshing when user input is detected. This effectively protects against burn-in while avoiding interference with the user's viewing experience. Therefore, it can solve the problem that existing technologies are unable to effectively protect against burn-in on advertising screens while ensuring a normal viewing experience for users.

[0012] As a preferred solution, screen status data of the advertising display device is obtained and a risk score is calculated based on a preset weighting method, specifically:

[0013] The screen status data is obtained from the advertising display device; wherein, the screen status data includes ambient light intensity, proportion of bright static area, and duration of static frame;

[0014] The screen status data is risk-scored according to a preset mechanism to obtain a risk score set;

[0015] The risk score is obtained by weighting the scores in the risk score set.

[0016] This preferred solution can promptly identify potential risks that may cause screen burn-in by monitoring screen status data. A risk score is obtained by weighting the scores in the risk score set, allowing for personalized risk assessments based on different users' screen usage needs and habits.

[0017] As a preferred embodiment, a pixel refresh mode corresponding to the risk score is executed on the anti-burn-in view, specifically as follows:

[0018] If the risk score is within a preset low-risk threshold range, then the pixel checkerboard mode is executed on the anti-burn-in view.

[0019] If the risk score is within the preset medium-risk threshold range, then a scrolling grayscale bar mode is executed on the anti-burn-in view.

[0020] If the risk score is within a preset high-risk threshold range, then a gradient background mode is executed on the anti-burn-in view.

[0021] This preferred solution divides the risk score into different threshold ranges, enabling the adoption of the most appropriate anti-burn-in mode for different risk levels. This precise matching helps improve the anti-burn-in effect while avoiding unnecessary resource consumption or excessive intervention. Furthermore, it ensures that while effectively preventing screen burn-in, it minimizes negative impacts on user experience, such as visual interference or operational inconvenience.

[0022] As a preferred embodiment, if the risk score is within a preset low-risk threshold range, then a pixel checkerboard mode is executed on the anti-burn-in view, specifically:

[0023] If the risk score is within the low-risk threshold range, a black and white checkerboard pattern is generated within the screen area of ​​the advertising display device, and the checkerboard pattern is set as the image content of the anti-burn-in view.

[0024] The checkerboard pattern is controlled to translate in a periodic manner along random directions, and the next direction of movement of the checkerboard pattern is randomly switched after each movement.

[0025] In this preferred solution, the black and white checkerboard pattern creates dynamic visual interference on the screen, effectively preventing burn-in caused by prolonged display of static images. Periodically moving the checkerboard pattern further disperses the fixed image on the screen, enhancing the anti-burn-in effect. Furthermore, in low-risk situations, choosing the relatively simple and effective pixel checkerboard pattern reduces system resource consumption.

[0026] As a preferred embodiment, if the risk score is within a preset medium-risk threshold range, then a scrolling grayscale bar mode is executed on the anti-burn-in view, specifically:

[0027] If the risk score is within the medium risk threshold range, a grayscale bar of fixed width is generated within the screen area of ​​the advertising display device, and the grayscale bar is set as the image content of the anti-burn-in view;

[0028] The grayscale bar is controlled to continuously scroll from one side of the advertising display device along the width of the screen to the other side in a cyclic manner.

[0029] In this preferred embodiment, the scrolling grayscale bar mode effectively disperses static images on the screen by generating and continuously scrolling a grayscale bar of fixed width, thereby enhancing the anti-burn-in effect. Furthermore, by periodically scrolling the grayscale bar, image information on the screen can be evenly distributed, reducing screen aging caused by displaying the same content for extended periods. In addition, the scrolling grayscale bar mode is a relatively low-resource-consuming anti-burn-in strategy. Adopting this mode in the medium-risk phase avoids the need to use more complex and energy-intensive anti-burn-in methods unnecessarily, thus making rational use of system resources.

[0030] As a preferred embodiment, if the risk score is within a preset high-risk threshold range, a gradient background mode is executed on the anti-burn-in view, specifically:

[0031] If the risk score is within the high-risk threshold range, the transparency of the anti-burn-in view is controlled to gradually decrease from opaque to completely transparent within a preset time range.

[0032] In this preferred embodiment, the gradient background mode continuously changes the image information on the screen by altering the transparency of the advertising display device, significantly reducing the risk of screen burn-in. Furthermore, the gradual change in transparency, rather than a sudden switch, helps users adapt to the change, thus minimizing negative impacts on user experience. In addition, immediately implementing the gradient background mode when the risk score reaches a high-risk threshold provides a rapid response to potential screen burn-in risks; this timely response helps prevent screen damage from prolonged display of static content, thereby extending the lifespan of the advertising display device.

[0033] As a preferred embodiment, when the risk score indicates that the screen of the advertising display device is under long-term static risk and the duration exceeds a first threshold, an anti-burn-in view is added to the overlay layer located between the main application window and the system-level window, specifically:

[0034] Obtain the timestamp of the last update of the screen of the advertising display device, and calculate the duration of the screen remaining static from the timestamp;

[0035] If the risk score indicates that the screen of the advertising display device is at long-term static risk and the duration exceeds the first threshold, then the anti-burn-in view is attached to the overlay located between the main application window and the system-level window.

[0036] This preferred solution calculates the static duration based on the timestamp of the last screen update, combining the risk score with the actual static duration as dual conditions. This avoids misjudgments that might occur if only the risk score is relied upon, ensuring that protection only activates when a genuine long-term static risk exists. The overlay layer is located between the main application window and the system-level window, neither obscuring the core content viewed by the user nor hindering the burning-out operation. This achieves physical isolation between the protection function and the displayed content, minimizing interference with normal viewing.

[0037] As a preferred option, the pixel refresh scheme includes a pixel checkerboard pattern, a scrolling grayscale bar pattern, and a gradient background pattern.

[0038] This application also provides a screen burn-in protection device for advertising display devices, including a reading module, a burn-in prevention module, a refresh module, and a removal module;

[0039] The reading module is used to acquire screen status data of the advertising display device and calculate a risk score based on a preset weighting method.

[0040] The anti-burn-in module is used to attach an anti-burn-in view to the overlay layer located between the main application window and the system-level window when the risk score indicates that the screen of the advertising display device is in a long-term static risk and the duration exceeds a first threshold.

[0041] A refresh module is used to execute a pixel refresh mode corresponding to the risk score on the anti-burn-in view; wherein the pixel refresh mode is at least one periodic pixel refresh scheme;

[0042] The removal module is used to terminate the pixel refresh mode and remove the anti-burn-in view when a user input signal is detected.

[0043] As a preferred embodiment, the reading module includes a data unit, a scoring unit, and a weighting unit;

[0044] The data unit is used to obtain screen status data from the advertising display device; wherein the screen status data includes ambient light intensity, proportion of bright static area, and duration of static frame.

[0045] The scoring unit is used to perform risk scoring on the screen status data according to a preset mechanism to obtain a risk score set.

[0046] The weighting unit is used to perform weighted calculations on the scores in the risk score set to obtain the risk score.

[0047] As a preferred embodiment, the refresh module includes a chessboard unit, a step unit, and a gradient unit;

[0048] The chessboard unit is used to execute a pixel chessboard grid mode on the anti-burn-in view if the risk score is in a preset low-risk threshold range.

[0049] The grayscale unit is used to execute a scrolling grayscale bar mode on the anti-burn-in view if the risk score is in a preset medium-risk threshold range.

[0050] The gradient unit is used to execute a gradient background mode on the anti-burn-in view if the risk score is in a preset high-risk threshold range.

[0051] As a preferred embodiment, the chessboard unit specifically comprises:

[0052] If the risk score is within the low-risk threshold range, a black and white checkerboard pattern is generated within the screen area of ​​the advertising display device, and the checkerboard pattern is set as the image content of the anti-burn-in view.

[0053] The checkerboard pattern is controlled to translate in a periodic manner along random directions, and the next direction of movement of the checkerboard pattern is randomly switched after each movement.

[0054] As a preferred embodiment, the stepped unit is specifically:

[0055] If the risk score is within the medium risk threshold range, a grayscale bar of fixed width is generated within the screen area of ​​the advertising display device, and the grayscale bar is set as the image content of the anti-burn-in view;

[0056] The grayscale bar is controlled to continuously scroll from one side of the advertising display device along the width of the screen to the other side in a cyclic manner.

[0057] As a preferred embodiment, the gradient unit is specifically:

[0058] If the risk score is within the high-risk threshold range, the transparency of the anti-burn-in view is controlled to gradually decrease from opaque to completely transparent within a preset time range.

[0059] As a preferred embodiment, the anti-scalding module includes a time unit and an anti-scalding unit;

[0060] The time unit is used to obtain the timestamp of the last update of the screen of the advertising display device, and to calculate the duration of the screen remaining static from the timestamp.

[0061] The anti-burn-in unit is configured to attach the anti-burn-in view to an overlay located between the main application window and the system-level window if the risk score indicates that the screen of the advertising display device is at long-term static risk and the duration exceeds the first threshold.

[0062] As a preferred option, the pixel refresh scheme includes a pixel checkerboard pattern, a scrolling grayscale bar pattern, and a gradient background pattern.

[0063] This application also provides a storage medium storing a computer program, which is invoked and executed by a computer to implement the screen burn-in protection method for advertising display devices as described above. Attached Figure Description

[0064] Figure 1 This is a schematic flowchart of a screen burn-in protection method for advertising display devices provided in an embodiment of this application;

[0065] Figure 2 This is a system flowchart provided in an embodiment of this application;

[0066] Figure 3 This is a schematic diagram of a screen burn-in protection device for advertising display equipment provided in an embodiment of this application. Detailed Implementation

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] In the description of this application, it should be understood that the term "first" is used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" may explicitly or implicitly include one or more of that feature.

[0069] The screen burn-in protection method for advertising display devices provided in this application aims to provide a non-intrusive, automated, multi-mode switching screen pixel protection mechanism, which can extend the service life of display devices while ensuring the continuity of advertising content.

[0070] Example 1:

[0071] Please see Figure 1 The embodiments of this application provide a screen burn-in protection method for advertising display devices, including S1 to S4, and the specific implementation steps are as follows:

[0072] S1. Obtain screen status data of the advertising display device and calculate the risk score based on a preset weighting method.

[0073] Step S1 in this embodiment includes S1.1 to S1.2, specifically as follows:

[0074] S1.1. Retrieve user-preset parameters from the system storage of the advertising display device according to a preset cycle, including anti-burn-in switch status, anti-burn-in mode type, cycle interval and single duration, etc.; and read the current screen image of the advertising display device.

[0075] After loading the user-preset parameters into memory, establish the triggering rules for scheduling logic, the user interaction listening mechanism, and the window attachment state listening mechanism.

[0076] Initialize the controller of the advertising display device to prepare for triggering the scheduling logic.

[0077] Among them, the user interaction monitoring mechanism is used to monitor the user's touch behavior on the screen in real time. Its trigger condition is any form of screen input signal, such as physical touch, remote control button, etc.

[0078] The window attachment status monitoring mechanism is used to monitor whether the anti-burn-in view is forcibly removed or covered due to system operations. Its trigger condition is that the anti-burn-in view is accidentally removed from the window layer, such as being obscured by a system pop-up.

[0079] In addition, listeners are enabled when the anti-burn-in view is actually visible to avoid meaningless event handling when the view is not displayed; listeners are automatically deactivated when the anti-burn-in view is removed to prevent accidental triggering caused by memory leaks or residual listeners.

[0080] S1.2. The data acquisition module obtains screen status data from the advertising display device. This screen status data includes ambient light intensity, the proportion of bright static areas, static frame duration, and screen activity level. The data acquisition module includes a brightness sensor monitoring submodule, a pixel distribution analysis submodule, an image frame persistence monitoring submodule, and a region change rate calculation submodule. The brightness sensor monitoring submodule collects ambient brightness values ​​(unit: lux) in real time to determine if the screen is in a high-brightness, high-voltage drive state. The pixel distribution analysis submodule captures a bitmap snapshot of the currently displayed content and identifies the proportion of bright static areas using RGB three-channel histogram statistics and a static area threshold determination algorithm. The image frame persistence monitoring submodule records the timestamps of screen content frame changes to determine if a frame remains unchanged. The region change rate calculation submodule continuously collects two frames of image content, calculates pixel differences, and determines the screen activity level.

[0081] The screen status data is risk-scored according to a preset mechanism to obtain a risk score set;

[0082] The risk score is obtained by weighting the scores in the risk score set.

[0083] In this embodiment S1, by monitoring screen status data, potential risks that may cause screen burn-in can be detected in a timely manner. By weighting the scores in the risk score set, a risk score can be obtained, which allows for personalized risk assessment based on different users' different needs and habits in screen use.

[0084] S2. When the risk score indicates that the screen of the advertising display device is in a long-term static risk and the duration exceeds the first threshold, an anti-burn-in view is attached to the overlay located between the main application window and the system-level window.

[0085] Step S2 in this embodiment of the application is specifically as follows:

[0086] Based on the scheduling logic triggering rules, obtain the timestamp of the last update of the current screen, and calculate the duration for which the screen remains static since the timestamp.

[0087] If the risk score indicates that the screen of the advertising display device is under prolonged static risk for a duration exceeding a preset threshold, then an anti-burn-in view (i.e., a high-priority view) is attached to the application interface of the advertising display device through an intermediate-level window. This view does not obscure the user's main content and is positioned below the system alarm window or lock screen window. In other words, an anti-burn-in view is attached to an overlay layer located between the main application window and the system-level window. The intermediate-level window is a specific window type set by the WindowManager, and its hierarchy is higher than the main application window, such as the main advertising interface, but lower than the system alarm window or lock screen window.

[0088] Furthermore, when the anti-burn-in view is added to the window of the advertising display device, the user interaction listening mechanism and the window attachment state listening mechanism are immediately initialized and activated to ensure timely response and exit of the anti-burn-in mode in the event of any user operation or window change.

[0089] In this embodiment, S2 calculates the static duration based on the timestamp of the last screen update, combining the risk score with the actual static duration as dual conditions. This avoids misjudgments that might occur if only the risk score is relied upon, ensuring that protection only activates when a long-term static risk actually exists. The overlay layer is located between the main application window and the system-level window, neither obscuring the core content viewed by the user nor hindering the anti-burn-in operation. This achieves physical isolation between the protection function and the displayed content, reducing interference with normal viewing.

[0090] S3. Execute the pixel refresh mode corresponding to the risk score on the anti-burn-in view; wherein the pixel refresh mode is at least one periodic pixel refresh scheme.

[0091] Step S3 in this embodiment of the application is specifically as follows:

[0092] Set a pixel refresh scheme, and the pixel refresh scheme is at least one periodic pixel refresh scheme, including pixel checkerboard mode, scrolling grayscale bar mode and gradient background mode and their equivalents.

[0093] If the risk score is in the low-risk threshold range (0-2 points), then the pixel checkerboard mode is executed on the anti-burn-in view.

[0094] If the risk score is in the medium risk threshold range (3-4 points), then the scrolling grayscale bar mode will be executed on the anti-burn-in view;

[0095] If the risk score is in the high-risk threshold range (≥5 points), then a gradient background mode is applied on the anti-burn-in view.

[0096] The following provides a detailed explanation of how each mode is executed:

[0097] ①Pixel checkerboard pattern: If the risk score is in the low-risk threshold range, a black and white checkerboard pattern (RGB bitmap) is generated within the screen area of ​​the advertising display device. Each grid is of fixed size and the black and white blocks are arranged alternately. The overall pattern of the checkerboard pattern is set to 50% transparency to ensure that the underlying content is visible, and the checkerboard pattern is set as the background or image content of the anti-burn-in view.

[0098] The chessboard pattern is controlled to move in a periodic manner along random directions, and the next movement direction of the chessboard pattern is randomly switched after each movement to avoid the pattern from staying still and causing new afterimages.

[0099] In this embodiment, the black and white checkerboard pattern can create dynamic visual interference on the screen, effectively preventing burn-in caused by prolonged display of static images. By periodically moving the checkerboard pattern, the fixed image on the screen can be further dispersed, enhancing the anti-burn-in effect. Furthermore, in low-risk situations, selecting the relatively simple and effective pixel checkerboard pattern can reduce system resource consumption.

[0100] ② Scrolling grayscale bar mode: If the risk score is in the medium risk threshold range, a grayscale bar with a width of 255 pixels is generated within the screen area of ​​the advertising display device. This grayscale bar is a horizontal grayscale gradient bar, and the grayscale bar is set as the background or image content of the anti-burn-in view; the grayscale bar is placed outside the left edge of the advertising display device, ready to scroll to the right;

[0101] Every 500 milliseconds, the grayscale bar moves 1 pixel to the right until it slides completely off the right side of the screen, then resets to the left side and starts again; the grayscale bar scrolls continuously through a looping animation, covering different areas of the screen.

[0102] In this embodiment, the scrolling grayscale bar mode effectively disperses static images on the screen by generating and continuously scrolling a grayscale bar of fixed width, thereby enhancing the anti-burn-in effect. Furthermore, by periodically scrolling the grayscale bar, image information on the screen can be evenly distributed, reducing screen aging caused by displaying the same content for extended periods. In addition, the scrolling grayscale bar mode is a relatively low-resource-consumption anti-burn-in strategy. Adopting this mode in the medium-risk phase avoids the need for more complex and energy-intensive anti-burn-in methods in unnecessary situations, thus making rational use of system resources.

[0103] ③ Gradient Background Mode: If the risk score is in the high-risk threshold range, the anti-burn-in view is controlled based on the characteristics of the intermediate layer window. The background color is driven to smoothly transition from pure white to pure black in 25 seconds using a linear interpolation algorithm. Then, within 2 seconds, the transparency is gradually increased from 0% to completely transparent by dynamically adjusting the Alpha channel (transparency channel), and the voltage layer of the entire screen is refreshed simultaneously.

[0104] In this embodiment, the gradient background mode continuously changes the image information on the screen by altering the transparency of the advertising display device, which greatly reduces the risk of screen burn-in. Furthermore, the gradual change in transparency, rather than a sudden switch, helps users adapt to the change, thereby reducing negative impacts on the user experience. In addition, when the risk score reaches a high-risk threshold, the gradient background mode is immediately activated, enabling a rapid response to potential screen burn-in risks; this timely response helps prevent screen damage from prolonged display of static content, thus extending the lifespan of the advertising display device.

[0105] In summary, this embodiment S3 divides the risk score into different threshold ranges, enabling the adoption of the most suitable anti-burn-in mode for different risk levels. This precise matching helps improve the anti-burn-in effect while avoiding unnecessary resource consumption or excessive intervention. In addition, it can ensure that while effectively preventing screen burn-in, it minimizes the negative impact on user experience, such as visual interference or inconvenience in operation.

[0106] S4. When a user input signal is detected, terminate the pixel refresh mode and remove the anti-burn-in view.

[0107] Step S4 in this embodiment includes S4.1 to S4.2, specifically as follows:

[0108] S4.1 Based on the user interaction monitoring mechanism, once any form of screen input signal is detected, such as user touch events and remote control input signals, the anti-burn-in mode is immediately terminated and the view is removed, restoring the advertiser's interface interaction.

[0109] Based on the window attachment state monitoring mechanism, if the anti-burn-in view is hidden due to a system pop-up, the current protection process is paused; after the pop-up closes, the screen state is re-checked. If the anti-burn-in view is accidentally removed due to an abnormal crash, resources are automatically cleaned up and the system waits for the next cycle of the detection process to ensure the continuous operation of subsequent protection.

[0110] S4.2 After terminating the anti-burn-in mode, execute the standardized resource reclamation protocol: explicitly reclaim bitmap resources such as checkerboard and grayscale bars through "Bitmap.recycle()" to release GPU video memory and system memory usage; call "WindowManager.removeView()" to remove the anti-burn-in view instance, completely severing its association reference with the window manager; simultaneously unbind event bindings such as user touch listeners and window attachment state callback interfaces related to the "user interaction listening mechanism and window attachment state listening mechanism" to eliminate potential memory leaks; at the same time, terminate and reset the animation instances that manage the dynamic behavior of the anti-burn-in view, such as ObjectAnimator (property animator) or AnimatorSet (animation set), to ensure that no residual state interferes with the next cycle;

[0111] After the resources are released, the system will re-enter standby mode and wait to start the next round of anti-burn detection process.

[0112] It should be noted that the scheduling logic's triggering rules include time-triggered rules, event-triggered rules, and risk level-triggered rules. The following section provides a detailed explanation of each rule in conjunction with each step:

[0113] ① Time-triggered rules: Define the time threshold for starting the anti-burn-in mode based on the user-set "periodic interval" and "single duration". For example: detect once every 15 minutes, and each anti-burn-in session lasts for 5 minutes (periodic data extraction in step S1).

[0114] ② Event Triggering Rules: Event triggering rules include screen state events, user input events, and system window events, specifically:

[0115] Screen status event: Static screen continues for more than a preset time (determination in step S2).

[0116] User input event: Exit triggered by touch or remote control signal (interaction listening in step S4).

[0117] System window event: Pop-up overlay causes the anti-burn-in view to be hidden (state listener for step S2).

[0118] ③ Risk level triggering rules: Through step S3, the risk score is mapped to different modes (low → checkerboard, medium → grayscale bar, high → gradient background).

[0119] Please see Figure 2 , Figure 2 This is a system flowchart provided in the embodiments of this application, which shows the general process of anti-burn-in scheduling and mode execution in this embodiment.

[0120] Overall, this embodiment has the following beneficial effects:

[0121] This application utilizes screen status data and a pre-calculated weighted risk score to activate protection only when the screen is under prolonged static risk for an duration exceeding a first threshold. This dynamic risk-level-based judgment avoids the interference of fixed-time forced refreshes on normal display, allowing intervention only when truly needed to ensure continuous viewing for the user. The protected view is attached as an overlay between the main application window and the system-level window, neither obscuring the main application content viewed by the user nor hindering the anti-burn-in operation. This layered design physically isolates the protection behavior from the core content viewed by the user, resolving the conflict between protection operations obscuring the main screen and the user experience. The pixel refresh mode corresponds to the risk score and employs a periodic pixel refresh scheme. A more efficient refresh mode is activated when the risk is high, while a lightweight mode is used when the risk is low. This dynamic adaptation avoids screen flickering or distortion caused by excessive refresh, effectively mitigating afterimage burn-in while minimizing the impact on the user's viewing experience. When a user input signal is detected, the refresh is immediately terminated and the anti-burn-in view is removed, preventing the protection behavior from interfering with the user's interaction with the device, further balancing protection needs and user experience.

[0122] In summary, this application sets up multiple anti-burn-in display modes and dynamically displays interference patterns in a high-transparency view on top of the displayed content. This allows for pixel refresh and dynamic changes without obscuring the main content, effectively reducing the risk of image ghosting.

[0123] Example 2:

[0124] Please see Figure 3 The embodiments of this application provide a screen burn-in protection device for advertising display devices, including a reading module 10, a burn-in protection module 20, a refresh module 30, and a removal module 40;

[0125] Among them, the reading module 10 is used to acquire screen status data of the advertising display device and calculate risk score based on a preset weighting method;

[0126] Anti-burn-in module 20 is used to attach an anti-burn-in view to the overlay located between the main application window and the system-level window when the risk score indicates that the screen of the advertising display device is in a long-term static risk and the duration exceeds a first threshold.

[0127] The refresh module 30 is used to execute a pixel refresh mode corresponding to the risk score on the anti-burn-in view; wherein the pixel refresh mode is at least one periodic pixel refresh scheme.

[0128] Remove module 40, which is used to terminate the pixel refresh mode and remove the anti-burn-in view when a user input signal is detected.

[0129] In one embodiment, the reading module 10 includes a setting unit, a data unit, a scoring unit, and a weighting unit;

[0130] The setting unit is used to retrieve user-preset parameters from the system storage of the advertising display device according to a preset period, including anti-burn-in switch status, anti-burn-in mode type, period interval and single duration, etc.; and to read the current screen image of the advertising display device.

[0131] The setting unit is also used to load user-preset parameters into memory and then establish the triggering rules for scheduling logic, the user interaction listening mechanism, and the window attachment state listening mechanism.

[0132] The setup unit is also used to initialize the controller of the advertising display device and prepare to trigger the scheduling logic.

[0133] Among them, the user interaction monitoring mechanism is used to monitor the user's touch behavior on the screen in real time. Its trigger condition is any form of screen input signal, such as physical touch, remote control button, etc.

[0134] The window attachment status monitoring mechanism is used to monitor whether the anti-burn-in view is forcibly removed or covered due to system operations. Its trigger condition is that the anti-burn-in view is accidentally removed from the window layer, such as being obscured by a system pop-up.

[0135] In addition, listeners are enabled when the anti-burn-in view is actually visible to avoid meaningless event handling when the view is not displayed; listeners are automatically deactivated when the anti-burn-in view is removed to prevent accidental triggering caused by memory leaks or residual listeners.

[0136] The data unit is used to acquire screen status data from the advertising display device using the data acquisition module. This screen status data includes ambient light intensity, the proportion of bright static areas, static frame duration, and screen activity level. The data acquisition module includes a brightness sensor monitoring submodule, a pixel distribution analysis submodule, an image frame persistence monitoring submodule, and a region change rate calculation submodule. The brightness sensor monitoring submodule collects ambient brightness values ​​(unit: lux) in real time to determine if the screen is in a high-brightness, high-voltage drive state. The pixel distribution analysis submodule captures a bitmap snapshot of the currently displayed content and identifies the proportion of bright static areas using RGB three-channel histogram statistics and a static area threshold determination algorithm. The image frame persistence monitoring submodule records the timestamps of screen content frame changes to determine if a frame remains unchanged. The region change rate calculation submodule continuously acquires two frames of image content, calculates pixel differences, and determines the screen activity level.

[0137] The scoring unit is used to score the screen status data according to a preset mechanism to obtain a risk score set.

[0138] The weighted unit is used to perform weighted calculations on the scores in the risk score set to obtain the risk score.

[0139] In this embodiment, the reading module 10 can promptly detect potential risks that may cause screen burn-in by monitoring screen status data. A risk score can be obtained by weighting the scores in the risk score set, allowing for personalized risk assessments based on different users' screen usage needs and habits.

[0140] In one embodiment, the anti-burn module 20 includes a time unit and an anti-burn unit;

[0141] The time unit is used to obtain the timestamp of the last update of the current screen based on the triggering rules of the scheduling logic, and to calculate the duration of the screen remaining static from the timestamp.

[0142] The anti-burn-in unit is used to attach an anti-burn-in view (i.e., a high-priority view) to the application interface of the advertising display device through an intermediate-level window if the risk score indicates that the screen of the advertising display device is in a prolonged static risk and the duration exceeds a preset threshold. This view does not obscure the user's main content and is placed below the system alarm window or lock screen window. In other words, the anti-burn-in view is attached to the overlay layer located between the main application window and the system-level window. The intermediate-level window is a specific window type set by WindowManager, and its hierarchy is higher than the main application window, such as the main advertising interface, but lower than the system alarm window or lock screen window.

[0143] Furthermore, when the anti-burn-in view is added to the window of the advertising display device, the user interaction listening mechanism and the window attachment state listening mechanism are immediately initialized and activated to ensure timely response and exit of the anti-burn-in mode in the event of any user operation or window change.

[0144] In this embodiment, the anti-burn-in module 20 calculates the static duration based on the timestamp of the last screen update, combining the risk score with the actual static duration as dual conditions. This avoids misjudgments that might occur if only the risk score is relied upon, ensuring that protection only activates when a prolonged static risk actually exists. The overlay layer is located between the main application window and the system-level window, neither obscuring the core content viewed by the user nor hindering the anti-burn-in operation. This achieves physical isolation between the protection function and the displayed content, reducing interference with normal viewing.

[0145] In one embodiment, the refresh module 30 includes a pattern unit, a chessboard unit, a step bar unit, and a gradient unit;

[0146] The mode unit is used to set the pixel refresh scheme, and the pixel refresh scheme is at least one periodic pixel refresh scheme, including pixel checkerboard mode, scrolling grayscale bar mode and gradient background mode and their equivalents.

[0147] The chessboard unit is used to execute the pixel chessboard grid mode on the anti-burn-in view if the risk score is in the low-risk threshold range (0-2 points).

[0148] The grayscale bar unit is used to execute a scrolling grayscale bar mode on the anti-burn-in view if the risk score is in the medium risk threshold range (3-4 points).

[0149] The gradient unit is used to apply a gradient background mode to the anti-burn-in view if the risk score is in the high-risk threshold range (≥5 points).

[0150] The following provides a detailed explanation of how each mode is executed:

[0151] ①Pixel checkerboard pattern: If the risk score is in the low-risk threshold range, a black and white checkerboard pattern (RGB bitmap) is generated within the screen area of ​​the advertising display device. Each grid is of fixed size and the black and white blocks are arranged alternately. The overall pattern of the checkerboard pattern is set to 50% transparency to ensure that the underlying content is visible, and the checkerboard pattern is set as the background or image content of the anti-burn-in view.

[0152] The chessboard pattern is controlled to move in a periodic manner along random directions, and the next movement direction of the chessboard pattern is randomly switched after each movement to avoid the pattern from staying still and causing new afterimages.

[0153] In this embodiment, the black and white checkerboard pattern can create dynamic visual interference on the screen, effectively preventing burn-in caused by prolonged display of static images. By periodically moving the checkerboard pattern, the fixed image on the screen can be further dispersed, enhancing the anti-burn-in effect. Furthermore, in low-risk situations, selecting the relatively simple and effective pixel checkerboard pattern can reduce system resource consumption.

[0154] ② Scrolling grayscale bar mode: If the risk score is in the medium risk threshold range, a grayscale bar with a width of 255 pixels is generated within the screen area of ​​the advertising display device. This grayscale bar is a horizontal grayscale gradient bar, and the grayscale bar is set as the background or image content of the anti-burn-in view; the grayscale bar is placed outside the left edge of the advertising display device, ready to scroll to the right;

[0155] Every 500 milliseconds, the grayscale bar moves 1 pixel to the right until it slides completely off the right side of the screen, then resets to the left side and starts again; the grayscale bar scrolls continuously through a looping animation, covering different areas of the screen.

[0156] In this embodiment, the scrolling grayscale bar mode effectively disperses static images on the screen by generating and continuously scrolling a grayscale bar of fixed width, thereby enhancing the anti-burn-in effect. Furthermore, by periodically scrolling the grayscale bar, image information on the screen can be evenly distributed, reducing screen aging caused by displaying the same content for extended periods. In addition, the scrolling grayscale bar mode is a relatively low-resource-consumption anti-burn-in strategy. Adopting this mode in the medium-risk phase avoids the need for more complex and energy-intensive anti-burn-in methods in unnecessary situations, thus making rational use of system resources.

[0157] ③ Gradient Background Mode: If the risk score is in the high-risk threshold range, the anti-burn-in view is controlled based on the characteristics of the intermediate layer window. The background color is driven to smoothly transition from pure white to pure black in 25 seconds using a linear interpolation algorithm. Then, within 2 seconds, the transparency is gradually increased from 0% to completely transparent by dynamically adjusting the Alpha channel (transparency channel), and the voltage layer of the entire screen is refreshed simultaneously.

[0158] In this embodiment, the gradient background mode continuously changes the image information on the screen by altering the transparency of the advertising display device, which greatly reduces the risk of screen burn-in. Furthermore, the gradual change in transparency, rather than a sudden switch, helps users adapt to the change, thereby reducing negative impacts on the user experience. In addition, when the risk score reaches a high-risk threshold, the gradient background mode is immediately activated, enabling a rapid response to potential screen burn-in risks; this timely response helps prevent screen damage from prolonged display of static content, thus extending the lifespan of the advertising display device.

[0159] In summary, the refresh module 30 in this embodiment divides the risk score into different threshold ranges, enabling it to adopt the most suitable anti-burn-in mode for different risk levels. This precise matching helps improve the anti-burn-in effect while avoiding unnecessary resource consumption or excessive intervention. In addition, it can ensure that while effectively preventing screen burn-in, it minimizes the negative impact on user experience, such as visual interference or inconvenience in operation.

[0160] In one embodiment, the removal module 40 includes a listening unit and a release unit;

[0161] The monitoring unit is used to immediately terminate the anti-burn-in mode and remove the view and restore the advertiser's interface interaction once any form of screen input signal is detected, such as user touch events and remote control input signals.

[0162] The monitoring unit also monitors the window attachment state. If the anti-burn-in view is hidden due to a system pop-up, the current protection process is paused; the screen state is re-checked after the pop-up is closed. If the anti-burn-in view is accidentally removed due to an abnormal crash, resources are automatically cleaned up and the system waits for the next cycle of detection to ensure the continued operation of subsequent protection.

[0163] The release unit is used to execute a standardized resource reclamation protocol after terminating the anti-burn-in mode: it explicitly reclaims bitmap resources such as checkerboard and grayscale bars through "Bitmap.recycle()", releasing GPU video memory and system memory usage; it calls "WindowManager.removeView()" to remove the anti-burn-in view instance, completely severing its association reference with the window manager; it synchronously unbinds event bindings such as user touch listeners and window attachment state callback interfaces related to the "user interaction listening mechanism and window attachment state listening mechanism", eliminating potential memory leaks; and it terminates and resets animation instances that manage the dynamic behavior of the anti-burn-in view, such as ObjectAnimator (property animator) or AnimatorSet (animation set), to ensure that no residual state interferes with the next cycle.

[0164] The release unit is also used so that after the resources are released, the system will re-enter the standby state and wait to start the next round of anti-burn detection process.

[0165] It should be noted that the scheduling logic's triggering rules include time-triggered rules, event-triggered rules, and risk level-triggered rules. The following section provides a detailed explanation of each rule in conjunction with each step:

[0166] ① Time-triggered rules: Define the time threshold for starting the anti-burn-in mode based on the user-set "periodic interval" and "single duration". For example: detect once every 15 minutes, and each anti-burn-in session lasts for 5 minutes (reading periodic data extraction from module 10).

[0167] ② Event Triggering Rules: Event triggering rules include screen state events, user input events, and system window events, specifically:

[0168] Screen status event: Static image lasts for more than a preset time (judgment by anti-burn-in module 20).

[0169] User input event: Touch or remote control signal triggers exit (remove interaction listener from module 40).

[0170] System window event: Pop-up overlay causes the anti-burn-out view to be hidden (status listener of anti-burn-out module 20).

[0171] ③ Risk level triggering rules: By refreshing module 30, the risk score is mapped to different modes (low → checkerboard, medium → grayscale bar, high → gradient background).

[0172] Please see Figure 2 , Figure 2 This is a system flowchart provided in the embodiments of this application, which shows the general process of anti-burn-in scheduling and mode execution in this embodiment.

[0173] Overall, this embodiment has the following beneficial effects:

[0174] This application utilizes screen status data and a pre-calculated weighted risk score to activate protection only when the screen is under prolonged static risk for an duration exceeding a first threshold. This dynamic risk-level-based judgment avoids the interference of fixed-time forced refreshes on normal display, allowing intervention only when truly needed to ensure continuous viewing for the user. The protected view is attached as an overlay between the main application window and the system-level window, neither obscuring the main application content viewed by the user nor hindering the anti-burn-in operation. This layered design physically isolates the protection behavior from the core content viewed by the user, resolving the conflict between protection operations obscuring the main screen and the user experience. The pixel refresh mode corresponds to the risk score and employs a periodic pixel refresh scheme. A more efficient refresh mode is activated when the risk is high, while a lightweight mode is used when the risk is low. This dynamic adaptation avoids screen flickering or distortion caused by excessive refresh, effectively mitigating afterimage burn-in while minimizing the impact on the user's viewing experience. When a user input signal is detected, the refresh is immediately terminated and the anti-burn-in view is removed, preventing the protection behavior from interfering with the user's interaction with the device, further balancing protection needs and user experience.

[0175] In summary, this application sets up multiple anti-burn-in display modes and dynamically displays interference patterns in a high-transparency view on top of the displayed content. This allows for pixel refresh and dynamic changes without obscuring the main content, effectively reducing the risk of image ghosting.

[0176] Example 3:

[0177] This application provides a computer-readable storage medium including a stored computer program, wherein the computer program, when running, controls the device where the computer-readable storage medium is located to execute the screen burn-in protection method for an advertising display device.

[0178] The screen burn-in protection method for advertising display devices, when implemented as a software functional unit and used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0179] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preventing screen burn-in in advertising display devices, characterized in that, include: Acquire screen status data of advertising display devices and calculate risk scores based on a preset weighting method; When the risk score indicates that the screen of the advertising display device is in a long-term static risk and the duration exceeds a first threshold, an anti-burn-in view is added to the overlay located between the main application window and the system-level window. A pixel refresh mode corresponding to the risk score is executed on the anti-burn-in view; wherein the pixel refresh mode is at least one periodic pixel refresh scheme; When a user input signal is detected, the pixel refresh mode is terminated and the anti-burn-in view is removed.

2. The screen burn-in protection method for advertising display devices as described in claim 1, characterized in that, The screen status data of the advertising display device is obtained and a risk score is calculated based on a preset weighting method, specifically as follows: The screen status data is obtained from the advertising display device; wherein, the screen status data includes ambient light intensity, proportion of bright static area, and duration of static frame; The screen status data is risk-scored according to a preset mechanism to obtain a risk score set; The risk score is obtained by weighting the scores in the risk score set.

3. The screen burn-in protection method for advertising display devices as described in claim 1, characterized in that, On the anti-burn-in view, execute the pixel refresh mode corresponding to the risk score, specifically as follows: If the risk score is within a preset low-risk threshold range, then the pixel checkerboard mode is executed on the anti-burn-in view. If the risk score is within the preset medium-risk threshold range, then a scrolling grayscale bar mode is executed on the anti-burn-in view. If the risk score is within a preset high-risk threshold range, then a gradient background mode is executed on the anti-burn-in view.

4. The screen burn-in protection method for advertising display devices as described in claim 3, characterized in that, If the risk score is within a preset low-risk threshold range, then a pixel checkerboard mode is executed on the anti-burn-in view, specifically: If the risk score is within the low-risk threshold range, a black and white checkerboard pattern is generated within the screen area of ​​the advertising display device, and the checkerboard pattern is set as the image content of the anti-burn-in view. The checkerboard pattern is controlled to translate in a periodic manner along random directions, and the next direction of movement of the checkerboard pattern is randomly switched after each movement.

5. A screen burn-in protection method for advertising display devices as described in claim 3, characterized in that, If the risk score is within a preset medium-risk threshold range, then a scrolling grayscale bar mode is executed on the anti-burn-in view, specifically: If the risk score is within the medium risk threshold range, a grayscale bar of fixed width is generated within the screen area of ​​the advertising display device, and the grayscale bar is set as the image content of the anti-burn-in view; The grayscale bar is controlled to continuously scroll from one side of the advertising display device along the width of the screen to the other side in a cyclic manner.

6. The screen burn-in protection method for advertising display devices as described in claim 3, characterized in that, If the risk score is within a preset high-risk threshold range, a gradient background mode is executed on the anti-burn-in view, specifically: If the risk score is within the high-risk threshold range, the transparency of the anti-burn-in view is controlled to gradually decrease from opaque to completely transparent within a preset time range.

7. The screen burn-in protection method for advertising display devices as described in claim 1, characterized in that, When the risk score indicates that the screen of the advertising display device is under long-term static risk and the duration exceeds a first threshold, an anti-burn-in view is added to the overlay located between the main application window and the system-level window, specifically: Obtain the timestamp of the last update of the screen of the advertising display device, and calculate the duration of the screen remaining static from the timestamp; If the risk score indicates that the screen of the advertising display device is at long-term static risk and the duration exceeds the first threshold, then the anti-burn-in view is attached to the overlay located between the main application window and the system-level window.

8. A screen burn-in protection method for advertising display devices as described in any one of claims 1-7, characterized in that, The pixel refresh scheme includes pixel checkerboard mode, scrolling grayscale bar mode, and gradient background mode.

9. A screen burn-in protection device for advertising display equipment, characterized in that, Includes a read module, an anti-burn module, a refresh module, and a remove module; The reading module is used to acquire screen status data of the advertising display device and calculate a risk score based on a preset weighting method. The anti-burn-in module is used to attach an anti-burn-in view to the overlay layer located between the main application window and the system-level window when the risk score indicates that the screen of the advertising display device is in a long-term static risk and the duration exceeds a first threshold. A refresh module is used to execute a pixel refresh mode corresponding to the risk score on the anti-burn-in view; wherein the pixel refresh mode is at least one periodic pixel refresh scheme; The removal module is used to terminate the pixel refresh mode and remove the anti-burn-in view when a user input signal is detected.

10. A screen burn-in protection device for advertising display equipment as described in claim 9, characterized in that, The reading module includes a data unit, a scoring unit, and a weighting unit; The data unit is used to obtain screen status data from the advertising display device; wherein the screen status data includes ambient light intensity, proportion of bright static area, and duration of static frame. The scoring unit is used to perform risk scoring on the screen status data according to a preset mechanism to obtain a risk score set. The weighting unit is used to perform weighted calculations on the scores in the risk score set to obtain the risk score.

11. The screen burn-in protection device for advertising display equipment as described in claim 9, characterized in that, The refresh module includes a chessboard unit, a step unit, and a gradient unit; The chessboard unit is used to execute a pixel chessboard grid mode on the anti-burn-in view if the risk score is in a preset low-risk threshold range. The grayscale unit is used to execute a scrolling grayscale bar mode on the anti-burn-in view if the risk score is in a preset medium-risk threshold range. The gradient unit is used to execute a gradient background mode on the anti-burn-in view if the risk score is in a preset high-risk threshold range.

12. The screen burn-in protection device for advertising display equipment as described in claim 11, characterized in that, The chessboard unit is specifically: If the risk score is within the low-risk threshold range, a black and white checkerboard pattern is generated within the screen area of ​​the advertising display device, and the checkerboard pattern is set as the image content of the anti-burn-in view. The checkerboard pattern is controlled to translate in a periodic manner along random directions, and the next direction of movement of the checkerboard pattern is randomly switched after each movement.

13. The screen burn-in protection device for advertising display equipment as described in claim 11, characterized in that, The stepped unit is specifically: If the risk score is within the medium risk threshold range, a grayscale bar of fixed width is generated within the screen area of ​​the advertising display device, and the grayscale bar is set as the image content of the anti-burn-in view; The grayscale bar is controlled to continuously scroll from one side of the advertising display device along the width of the screen to the other side in a cyclic manner.

14. The screen burn-in protection device for advertising display equipment as described in claim 11, characterized in that, The gradient unit is specifically: If the risk score is within the high-risk threshold range, the transparency of the anti-burn-in view is controlled to gradually decrease from opaque to completely transparent within a preset time range.

15. A screen burn-in protection device for advertising display equipment as described in claim 9, characterized in that, The anti-scalding module includes a time unit and an anti-scalding unit; The time unit is used to obtain the timestamp of the last update of the screen of the advertising display device, and to calculate the duration of the screen remaining static from the timestamp. The anti-burn-in unit is configured to attach the anti-burn-in view to an overlay located between the main application window and the system-level window if the risk score indicates that the screen of the advertising display device is at long-term static risk and the duration exceeds the first threshold.

16. A screen burn-in protection device for advertising display equipment as described in any one of claims 9-15, characterized in that, The pixel refresh scheme includes pixel checkerboard mode, scrolling grayscale bar mode, and gradient background mode.

17. A storage medium, characterized in that, The storage medium stores a computer program, which is called and executed by a computer to implement a screen burn-in protection method for an advertising display device as described in any one of claims 1 to 8.

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