Method and device for monitoring a local dimming function of a display device for a vehicle and display device for a vehicle

Abstract

Method for monitoring a local dimming function of a display device for a vehicle during an active display operation of the display device. The display device comprises a matrix backlight unit and is configured for displaying an image having at least partially safety-related content and in differently dimmable zones. A predefined watermark is applied to image data which shall be processed to produce supplemented image data. The watermark is added to a segment of image data which is attributed to a hidden area of a screen of the display device. The local dimming function is implemented on the supplemented image data, a luminance is calculated for each of the zones based on the supplemented image data and a pixel compensation is performed based on the calculated luminances. A first comparison of the calculated luminance for a zone in which the watermark shall be displayed with a predefined reference luminance and a second comparison of a signature determined for the watermark after the pixel compensation with a predefined reference signature are performed to produce monitoring data depending on the results of the comparisons.

Description

Technical Field

[0001] This invention relates to an apparatus or method of the kind described in the independent claims. A computer program is also the subject of this invention. Existing technology

[0002] Display products used for dashboard (cluster) content or safety-related content in vehicles should correctly and completely display the received video stream. This constitutes a safety objective. Random hardware failures in local-dimming control devices or local-dimming controllers can lead to a breach of this safety objective, potentially resulting in the following risks: unreliable display of safety-related content on the display device; incomplete images may be produced, where the brightness of backlight areas behind the safety-related content may be incorrectly calculated; incorrect images may also be produced, where pixel compensation may manipulate the safety-related content, rendering it invisible. Traditional monitoring functions, in particular, must know the location of the safety-related area in order to monitor whether that area has been correctly calculated.

[0003] EP 2 372 686 A1 relates to a method for enhancing local dimming in an LED backlighting display device when using prominent features. Summary of the Invention

[0004] In this context, by means of the proposed solution, a method according to the main claim, an apparatus using the method, a display device, and a corresponding computer program are proposed. Advantageous extensions and improvements to the apparatus described in the independent claim can be achieved through the measures enumerated in the dependent claims.

[0005] According to the implementation, in particular, online monitoring of the local dimming function of display devices for vehicles can be provided. Advantageously, for example, it can be made possible to identify random hardware faults during pixel compensation and zone brightness calculations of the local dimming controller. Furthermore, it can be achieved that pixel compensation correctly matches the entire image and that zone brightness is correctly calculated for each zone. Therefore, for example, it can be ensured that the complete image or full-frame image is displayed correctly and completely. Thus, the main device connected to the display device advantageously does not need to separate those display areas where safety-related content is displayed. Therefore, the full image or complete image can be securely processed through serial processing and online watermarking. In display devices or display products, the required ASIL compliance can be ensured, in particular, by using ASIL-compliant hardware components and ASIL-compliant software development.

[0006] A method is proposed for monitoring the local dimming function of a display device for a vehicle, wherein the method can be implemented during the active display operation of the display device, wherein the display device has a matrix backlight unit and is configured to display an image having at least partially safety-related content and to be displayed in areas where dimming is possible, wherein the method comprises the following steps: At least one predefined watermark is applied to image data representing an image that should be displayed by a display device and should be processed by a local dimming function to produce supplemented image data, wherein at least one watermark is added to the following sections of the image data: the sections belong to the hidden areas of the screen of the display device and / or the display areas that are not used by the image content of the image that should be displayed; Local dimming is implemented on supplemented image data, wherein brightness is calculated for each region based on the supplemented image data, and pixel compensation is performed based on the calculated brightness; and A first comparison is performed between the brightness calculated for the area in which the at least one watermark should be displayed and a predefined reference brightness for the at least one watermark, and a second comparison is performed between the signature determined for the at least one watermark after pixel compensation and a predefined reference signature for the at least one watermark, so as to generate monitoring data based on the results of these comparisons.

[0007] The vehicle can be a motor vehicle, such as a passenger car, motorcycle, truck, or other commercial vehicle. The display device can be specified for fixed mounting in the vehicle or can be fixedly mounted in the vehicle. Safety-related content can relate to the vehicle's driving functions, current traffic conditions, and additionally or alternatively, warnings. During active display operation, an image having at least partially safety-related content can be displayed or can be shown using the display device. The hidden area of ​​the display device's screen can be arranged outside the effective image area. The hidden area of ​​the screen can correspond to a segment of image data involving blanking areas. The display area not used by the image content of the image that should be displayed can correspond to a black area in the displayed image. Optionally, at least one watermark can be additionally covered with a black overlay to obscure at least one watermark.

[0008] According to one implementation, grayscale and RGB watermarks can be applied to image data during the application step. Applying a grayscale watermark allows for checking the accuracy of the brightness calculations for the local dimming function. Applying an RGB watermark allows for checking the accuracy of pixel compensation for the local dimming function. Therefore, these two watermarks enable comprehensive and secure monitoring of the local dimming function.

[0009] Here, a first comparison can be performed during the execution step between the calculated brightness of the area where the grayscale watermark should be displayed and a predefined reference brightness for the grayscale watermark. This allows for simple, fast, and reliable monitoring of the area brightness calculation for local dimming functionality in terms of errors.

[0010] Here, a second comparison can also be performed during the execution step between the signature determined for the RGB watermark after pixel compensation and a predefined reference signature for the RGB watermark. This method enables simple, fast, and reliable monitoring of pixel compensation for local dimming functions in terms of errors.

[0011] Furthermore, the local dimming function can be implemented in this step by setting the brightness of the RGB watermark area to a fixed preset value. This eliminates the correlation with the global brightness of the image data.

[0012] Furthermore, if the result of at least one of the comparisons shows a deviation below a predefined threshold, the monitoring data generated in the execution step can represent the compliant state of the local dimming function. Conversely, if the result of at least one of the comparisons shows a deviation above a predefined threshold, the monitoring data generated in the execution step can represent a faulty state of the local dimming function. This method allows for a simple and safe identification of whether the local dimming function is functioning normally or is faulty, such as due to a hardware malfunction.

[0013] This method can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, such as in a control device.

[0014] The proposed solution further provides an apparatus configured to perform, manipulate, or implement variations of the method proposed herein within a corresponding device or unit. This apparatus-based embodiment of the invention also enables the rapid and efficient resolution of the task upon which the invention is based.

[0015] Therefore, the device may have at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface for reading sensor signals from sensors or outputting data signals or control signals to actuators, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The computing unit may be, for example, a signal processor, a microcontroller, etc., and the memory unit may be a flash memory or magnetic storage unit. The communication interface may be configured for wirelessly and / or wiredly reading or outputting data, wherein the communication interface capable of reading or outputting wired data may, for example, read such data from or output such data to a corresponding data transmission line electrically or optically.

[0016] In the current context, the device can be understood as an electrical device that processes sensor signals and outputs control signals and / or data signals accordingly. The device may have an interface, which can be constructed in hardware and / or software. In a hardware construction, the interface may, for example, be part of a so-called system ASIC that contains various functions of the device. However, it is also possible that the interface is its own integrated circuit or at least partially composed of discrete structural elements. In a software construction, the interface may be, for example, a software module that resides on a microcontroller along with other software modules.

[0017] A display device for vehicles is also proposed, wherein the display device has the following features: Matrix background lighting unit; and In one embodiment of the device mentioned herein, the device and the matrix backlighting unit are interconnected in a manner capable of transmitting data.

[0018] In conjunction with a display device, implementations of the devices mentioned herein can be advantageously applied or used to monitor the local dimming function of the display device.

[0019] It is also advantageous to have a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as semiconductor memory, hard disk memory or optical memory, and is used, in particular, when the program product or program is executed on a computer or device, to perform, implement and / or manipulate the steps of the method according to one of the foregoing embodiments. Attached Figure Description

[0020] Embodiments of the proposed solution are shown in the accompanying drawings and described in more detail in the following description. Wherein: Figure 1 A schematic diagram illustrating an embodiment of a display device for a vehicle; Figure 2 A schematic diagram illustrating an embodiment of a device for monitoring the local dimming function of a display device for a vehicle; and Figure 3 A flowchart illustrating an embodiment of a method for monitoring the local dimming function of a display device for a vehicle.

[0021] In the following description of advantageous embodiments of the invention, the same or similar reference numerals are used for elements shown in different figures and functioning similarly, wherein repeated descriptions of these elements are omitted. Detailed Implementation

[0022] Figure 1 This diagram illustrates an embodiment of a display device 100 for a vehicle. The display device 100 is fixedly mounted in or designed for fixed mounting within a vehicle. The display device 100 can be connected to a host device H or host unit, such as a vehicle control device, via a data connection, such as a so-called High-Speed ​​Video-Link (HSVL). The display device 100 is configured to read or receive video signals from the host device H via the data connection. The display device 100 can be connected to a network N or a power grid via an electrical connection.

[0023] Display device 100 includes a matrix backlighting unit 114 and a device 124 for monitoring the local dimming function of display device 100. Here, device 124 and matrix backlighting unit 114 are interconnected in a manner capable of data transmission. Display device 100 is configured to display images having at least partially security-related content and to display in areas where dimming is possible. Device 124 is configured to monitor the local dimming function of display device 100 during active display operation. Device 124 will be discussed in further detail with reference to the accompanying drawings described below.

[0024] Display device 100 includes, for example, a display module 110 having a display circuit board 112, a backlight unit or matrix backlight unit 114, and a cover glass 116. Additionally, display device 100 includes, for example, a system circuit board 120 having a serial-to-parallel converter or deserializer 122, a device 124 for monitoring the local dimming function of display device 100, a local dimming controller 126 or local dimming control device, and a microcontroller 128.

[0025] Deserializer 122 is configured to receive video signals from host device H via a data connection. Furthermore, deserializer 122 is configured to output image data 132 to local dimming controller 126 and global brightness value 133 to microcontroller 128. Microcontroller 128 is configured to output global brightness value 133 to local dimming controller 126. Local dimming controller 126 is configured to implement local dimming functionality on image data 132 and output supplemented image data 135 to display module 110, more specifically to display circuit board 112. Local dimming controller 126 is configured to output zone brightness value 136 to microcontroller 128, the zone brightness value representing a calculated brightness or brightness value for said zone. Microcontroller 128 is configured to output zone brightness value 136 to display module 110, more specifically to matrix backlight unit 114.

[0026] In other words, the display device 100, equipped with a matrix backlighting unit 114 and local dimming functionality, can match the received screen content or image data 132 and control the brightness of the area behind the video content. The local dimming controller 126 calculates the area brightness for the matrix backlighting based on the image data 132 or video content for each area. The local dimming controller 126 matches the screen content according to the brightness of the corresponding area, achieving grayscale equalization. The microcontroller 128 transmits the area brightness value 136 or a value for the area brightness to the matrix backlighting unit 114. The display device 100 can meet the ISO 26262 requirements for controllable luminaires with ASIL B. In this case, the main device H can also be implemented with secure video output according to ISO 26262 ASIL B.

[0027] Figure 2 A schematic diagram illustrates an embodiment of a device 124 for monitoring the local dimming function of a display device for a vehicle. In this case, device 124 is equivalent to or similar to... Figure 1 The device 124 in this case includes a local dimming controller 126 and a microcontroller 128.

[0028] The configuration device 201 of the microcontroller 128 receives a global brightness value 133. The configuration device 201 is configured to configure at least one watermark and output a configuration signal 231 to the application device 202 and the first implementation device 204A of the local dimming controller 126. Furthermore, the configuration device 201 is configured to output a reference area brightness value 236 to the first execution device 206A of the microcontroller 128 and to output a reference signature 238 to the second execution device 206B of the microcontroller 128.

[0029] Application device 202 of local dimming controller 126 receives image data 132 and configuration signal 231. Application device 202 is configured to apply at least one predefined watermark to image data 132, which represents an image to be displayed by a display device, in order to generate supplemented image data 135. Application device 202 is configured to add at least one watermark to segments of image data 132 that belong to hidden areas of the screen of the display device and / or display areas not utilized by image content of the image to be displayed. Optionally, local dimming controller 126 additionally includes an additional unit or device configured to overlay the at least one watermark with a black overlay to cover the at least one watermark. Application device 202 is configured to output the supplemented image data 135 to a first implementation device 204A and a second implementation device 204B of local dimming controller 126.

[0030] The first implementation device 204A and the second implementation device 204B of the local dimming controller 126 are configured to implement a local dimming function on the supplemented image data 135. Here, the first implementation device 204A is configured to perform image evaluation and calculate brightness for each region based on the supplemented image data 135 to provide a region brightness value 136. The first implementation device 204A is configured to output the region brightness value 136 to the second implementation device 204B and the first execution device 206A of the microcontroller 128. The second implementation device 204B is configured to perform pixel compensation for each region based on the calculated brightness and output the supplemented image data 135 processed in this way to the signature checking device 205.

[0031] The signature checking device 205 is configured to provide supplemented image data 135 to the display unit of the display device on the one hand, and to determine a signature for at least one watermark on the other hand and output the determined signature 237 to the second execution device 206B of the microcontroller 128.

[0032] The first actuation device 206A of the microcontroller 128 is configured to perform a first comparison between the brightness calculated from the area brightness value 136 for the area in which the at least one watermark should be displayed and the predefined reference brightness from the reference area brightness value 236 for the at least one watermark. Therefore, the first actuation device 206A is configured to perform brightness monitoring.

[0033] The second execution device 206B of the microcontroller 128 is configured to perform a second comparison, after pixel compensation, between the signature 237 determined for the at least one watermark and a predefined reference signature 238 for the at least one watermark. Therefore, the second execution device 206B is configured to perform a signature check.

[0034] The device 124, and in particular the microcontroller 128, is also configured to generate monitoring data 239 based on the results of a first comparison performed by the first actuator 206A and a second comparison performed by the second actuator 206B.

[0035] In other words, based on the at least one watermark, the functionality of pixel compensation performed by the second implementation device 204B and the brightness calculation performed by the first implementation device 204A can be verified against a reference image, wherein the results of the pixel compensation and area brightness calculation are known. Conventional implementations using test patterns can only perform checks at startup because the test pattern should not be visible during operation. Online local dimming monitoring via device 124 sets two predefined watermarks on frames or images in invisible or inaccessible hidden areas of the screen: a grayscale watermark for checking the correctness of the brightness calculation and an RGB watermark for checking the correctness of the pixel compensation, wherein the area brightness is set to a standard value. If the watermarks are processed correctly, the entire image is also processed correctly because the video data is processed serially, e.g., pixel-by-pixel, line-by-line, or area-by-area.

[0036] Local dimming controller 126 sets a predefined watermark to the video stream or image data 132, for example, via OSD functionality. The watermark can be configured, for example, via microcontroller 128. Microcontroller 128 configures the image evaluation and brightness calculation of the first implementation device 204A such that the brightness in the RGB watermark area is set to a fixed predefined value. The reference area brightness 236 of the watermark is calculated and stored on microcontroller 128 during development. Local dimming controller 126 processes the complete image (frame) containing the watermark as supplemented image data 135. Pixel compensation performed by the second implementation device 204B is related to the area brightness and therefore also to the global brightness. Therefore, the brightness in the RGB watermark area is set to a fixed value to eliminate the correlation with the global brightness.

[0037] After image evaluation and brightness calculation performed by the first implementation device 204A, the brightness monitoring of the first execution device 206A compares the reference area brightness value 236 for the grayscale watermark area with the actual brightness of that area from the area brightness value 136. Since the area brightness is related to the global brightness, the reference area value for the watermark is calculated based on the global brightness. The signature unit or signature checking device 205 checks the signature 237 of the RGB watermark area and sends the signature to the microcontroller 128. The microcontroller 128, more specifically the second execution device 206B, compares the RGB watermark signature 237 with the reference signature 238 for that watermark.

[0038] Figure 3 A flowchart illustrating an embodiment of a method 300 for monitoring the local dimming function of a display device for a vehicle is shown. The monitoring method 300 can be combined with... Figure 1 The monitoring method 300 is implemented using a display device or similar device, namely a display device having a matrix backlight unit and configured to display images having at least partially security-related content and displaying in areas capable of different dimming. The monitoring method 300 can be implemented during the active display operation of the display device. Here, the monitoring method 300 can be implemented using the device shown in one of the above figures or when using the device shown in one of the above figures. The monitoring method 300 includes an application step 302, an implementation step 304, and an execution step 306.

[0039] In step 302, at least one predefined watermark is applied to image data representing an image to be displayed using a display device, which should be processed by the local dimming function, to generate supplemented image data. Here, at least one watermark is added to the following sections of the image data: these sections belong to hidden areas of the screen of the display device and / or display areas not utilized by the image content of the image to be displayed.

[0040] In step 304, a local dimming function is implemented on the supplemented image data. Here, the brightness is calculated for each region based on the supplemented image data, and pixel compensation is performed based on the calculated brightness.

[0041] In step 306, a first comparison is performed between the brightness calculated for the area in which the at least one watermark should be displayed and a predefined reference brightness for the at least one watermark, and a second comparison is performed between the signature determined for the at least one watermark after pixel compensation and a predefined reference signature for the at least one watermark, so as to generate monitoring data based on the results of the comparisons.

[0042] According to one embodiment, in application step 302, grayscale and RGB watermarks are applied to the image data. In this case, in implementation step 304, a local dimming function is implemented such that the brightness in the RGB watermark area is set to a fixed predefined value. Here, in execution step 306, a first comparison is performed between the brightness calculated for the area in which the grayscale watermark should be displayed and a predefined reference brightness for the grayscale watermark. Here, in execution step 306, a second comparison is also performed between the signature determined for the RGB watermark after pixel compensation and a predefined reference signature for the RGB watermark.

[0043] According to one embodiment, the monitoring data generated in step 306 represents a compliant state of the local dimming function when the result of at least one of the comparisons shows a deviation below a threshold, and represents a faulty state of the local dimming function when the result of at least one of the comparisons shows a deviation above a threshold.

[0044] If an embodiment includes an "and / or" connection between a first feature and a second feature, this can be interpreted as such that the embodiment, according to one implementation, has not only the first feature but also the second feature, and according to another implementation, has either only the first feature or only the second feature.

Claims

1. A method (300) for monitoring the local dimming function of a display device (100) for a vehicle, wherein the method (300) can be implemented during the active display operation of the display device (100), wherein the display device (100) has a matrix backlighting unit (114) and is configured to display an image having at least partially safety-related content and to be displayed in areas where dimming is possible, wherein the method (300) comprises the following steps: At least one predefined watermark is applied (302) to image data (132) representing an image to be displayed by means of the display device (100), which should be processed by the local dimming function, to produce supplemented image data (132), wherein the at least one watermark is added to the image data in the following segments: the segments belong to the hidden area of ​​the screen of the display device (100) and / or the display area not used by the image content of the image to be displayed; The local dimming function described in (304) is implemented on the supplemented image data (135), wherein brightness is calculated for each region in the region based on the supplemented image data (135), and pixel compensation is performed based on the calculated brightness; and Perform (306) a first comparison of the brightness (136) calculated for the area in which the at least one watermark should be displayed with a reference brightness (236) predefined for the at least one watermark, and a second comparison of the signature (237) determined for the at least one watermark after pixel compensation with a reference signature (238) predefined for the at least one watermark, so as to generate monitoring data (239) based on the results of the comparisons.

2. The method (300) according to claim 1, wherein in the application step (302), grayscale watermark and RGB watermark are applied to the image data (132).

3. The method (300) according to claim 2, wherein in the execution step (306), a first comparison is performed between a brightness (136) calculated for the area in which the grayscale watermark should be displayed and a reference brightness (236) predefined for the grayscale watermark.

4. The method (300) according to any one of claims 2 to 3, wherein in the execution step (306), a second comparison is performed between the signature (237) determined for the RGB watermark after the pixel compensation and a reference signature (238) predefined for the RGB watermark.

5. The method (300) according to any one of claims 2 to 4, wherein in the implementation step (304), the local dimming function is implemented such that the brightness in the RGB watermark area is set to a fixed preset value.

6. The method (300) according to any one of the preceding claims, wherein if the result of at least one of the comparisons shows a deviation below a threshold, the monitoring data (239) generated in the execution step (306) represents a compliant state of the local dimming function, and if the result of at least one of the comparisons shows a deviation above a threshold, the monitoring data (239) generated in the execution step (306) represents a faulty state of the local dimming function.

7. An apparatus (124) configured to perform and / or manipulate the steps of the method (300) according to any one of the preceding claims in corresponding units (201, 202, 204A, 204B, 205, 206A, 206B).

8. The device (124) according to claim 7, the device having the corresponding units (201, 202, 204A, 204B, 205, 206A, 206B), wherein the corresponding units (201, 202, 204A, 204B, 205, 206A, 206B) are specifically configured as a configuration device (201), an application device (202), a first implementation device (204A), a second implementation device (204B), a first execution device (206A), and a second execution device (206B).

9. A display device (100) for a vehicle, wherein the display device (100) has the following features: Matrix background lighting unit (114); and The device (124) according to any one of claims 7 to 8, wherein the device (124) and the matrix background lighting unit (114) are interconnected in a manner capable of transmitting data.

10. A computer program configured to perform and / or manipulate the steps of the method (300) according to any one of claims 1 to 6.

11. A machine-readable storage medium on which a computer program according to claim 10 is stored.

Images