Fail-safe architecture for local dimming display devices

Abstract

A display device includes a backlight device and a local dimming circuit. The backlight device includes a plurality of light sources configured to illuminate the display panel. The local dimming circuit is configured to individually control brightness levels of the plurality of light sources based on first input image data in a first local dimming mode. The local dimming circuit is further configured to enter a failure mode in response to a failure of at least one of the plurality of light sources and to control brightness levels of other of the plurality of light sources to a predetermined brightness level in the failure mode.

Description

Technical Field

[0001] The present disclosure generally relates to display devices and more particularly to a fail-safe architecture for a display device having a local dimming function. Background Art

[0002] A panel display device having a transmissive display panel (e.g., a transmissive liquid crystal display (LCD) panel) may include a backlight device that illuminates the transmissive display panel. Modern backlight devices (such as direct-lit backlights, full-array backlights, etc.) may be configured to illuminate the display panel using a two-dimensional (2D) array of light sources (e.g., light-emitting diodes (LEDs)). The use of a 2D light source array in the backlight device enables an implementation of a local dimming function that can achieve high dynamic contrast and low power consumption by individually controlling the respective light sources of the 2D light source array according to input image data. Summary of the Invention

[0003] This summary of the invention is intended to introduce a selection of concepts in a simplified form that are further described below. This summary of the invention is not intended to identify key features or essential features of the present disclosure. The present disclosure may include the following various aspects and embodiments.

[0004] In an exemplary embodiment, the present disclosure provides a display device that includes a backlight device and a local dimming circuit. The backlight device includes a plurality of light sources configured to illuminate a display panel. The local dimming circuit is configured to individually control the brightness levels of the plurality of light sources based on first input image data in a first local dimming mode. The local dimming circuit is further configured to enter a failure mode in response to a failure of at least one of the plurality of light sources and to control the brightness levels of the other light sources among the plurality of light sources to a predetermined brightness level in the failure mode.

[0005] In another exemplary embodiment, the present disclosure provides a display driver that includes a local dimming circuit and a driver circuit. The local dimming circuit is configured to individually control the brightness levels of a plurality of light sources of a backlight device based on first input image data in a first local dimming mode. The plurality of light sources are configured to illuminate a display panel. The local dimming circuit is further configured to enter a failure mode in response to a failure of at least one of the plurality of light sources and to control the brightness levels of the other light sources among the plurality of light sources to a predetermined brightness level in the failure mode. The driver circuit is configured to drive the display panel based on the first input image data.

[0006] In yet another exemplary embodiment, the present disclosure provides a method. The method includes placing a local dimming circuit in a first local dimming mode. The method further includes separately controlling, by the local dimming circuit in the first local dimming mode, brightness levels of a plurality of light sources of a backlight device based on first input image data. The method further includes placing the local dimming circuit in a failure mode in response to failure of at least one of the plurality of light sources. The method further includes controlling, by the local dimming circuit in the failure mode, brightness levels of other light sources among the plurality of light sources to a predetermined brightness level.

[0007] Other features and aspects are described in more detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Shows an example configuration of a display device according to one or more embodiments.

[0009] Figure 2 Shows an example arrangement of light sources of a backlight device according to one or more embodiments.

[0010] Figure 3 Shows an example configuration of a local dimming circuit according to one or more embodiments.

[0011] Figure 4 Shows an example of a compensated gamma curve determined for pixels located in a region corresponding to a failed light source according to one or more embodiments.

[0012] Figure 5 Is a flowchart showing an example method according to one or more embodiments.

[0013] Figure 6 Shows an example configuration of a display device according to other embodiments.

[0014] Figure 7A Shows an example of light source failure compensation according to one or more embodiments.

[0015] Figure 7B Shows another example of light source failure compensation according to one or more embodiments.

[0016] Figure 8A Shows an example configuration of a local dimming circuit according to one or more embodiments.

[0017] Figure 8B Shows an example configuration of a backlight control circuit according to one or more embodiments.

[0018] Figure 9 Is a flowchart showing an example method according to one or more embodiments.

[0019] Figure 10 An example of average picture levels (APLs) of corresponding areas of a display panel according to one or more embodiments is shown.

[0020] Figure 11 An example of a zone corner APL determined for a corresponding zone corner according to one or more embodiments is shown.

[0021] Figure 12 An example operation of a pixel APL for a pixel is shown in accordance with one or more embodiments.

[0022] Figure 13 An example relationship between a gamma value and a pixel APL according to one or more embodiments is shown.

[0023] Figure 14 An example use of a hypothetical APL for a zone corresponding to a failed light source is shown in accordance with one or more embodiments.

[0024] For ease of understanding, the same reference numerals have been used, where possible, to designate elements common to the drawings. It is contemplated that elements disclosed in one embodiment may be used in other embodiments without specific description. Suffixes may be added to reference numerals to distinguish elements from one another. Unless specifically noted, the drawings cited herein are not to be interpreted as being drawn to scale. In addition, for clarity of presentation and explanation, the drawings are usually simplified and details or components are omitted. The drawings and discussion are used to explain the principles discussed below. DETAILED DESCRIPTION

[0025] The following specific embodiments are exemplary in nature and are not intended to limit the present disclosure or the application and use of the present disclosure. In addition, it is not intended to be subject to any express or implied theoretical constraints presented in the background technology, summary of the invention and the accompanying drawings or in the following specific embodiments. In the following specific embodiments, many specific details are set forth in order to provide a more thorough understanding of the disclosed technology. However, it will be apparent to those of ordinary skill in the art that the disclosed technology can be practiced in the absence of these specific details. In other examples, well-known features have not yet been described in detail to avoid unnecessarily complicating this description.

[0026] As used herein, the term "coupled" means directly connected to or connected through one or more intermediate components or circuits. Further, throughout this application, ordinal numbers (e.g., first, second, third, etc.) may be used as adjectives for an element (i.e., any noun in this application). Unless explicitly disclosed, such as by using terms like "before", "after", "single", and other such terms, the use of ordinal numbers is not intended to imply or create any particular ordering of elements, nor is it intended to limit any element to only a single element. Instead, the use of ordinal numbers is to distinguish between elements. By way of example, a first element is different from a second element, and the first element may include more than one element and be after (or before) the second element in the ordering of elements.

[0027] A panel display device having a transmissive display panel (e.g., a transmissive liquid crystal display (LCD) panel) may include a backlight device configured to illuminate the display panel using a two-dimensional (2D) array of light sources (e.g., light emitting diodes (LEDs)). The use of a 2D light source array in the backlight device enables an implementation of a local dimming function that can achieve high dynamic contrast and low power consumption by individually controlling corresponding light sources of the 2D light source array according to input image data.

[0028] In actual use, one or more light sources of the backlight device may fail due to aging, mechanical shock, and / or electrical shock or other reasons. Since a failed light source may not emit light as desired, the failure of one or more light sources may result in partial display loss on the display panel, which may cause inconvenience to the user of the display device. Additionally, in some situations (such as automotive applications), for safety reasons, it may be desirable to avoid partial display loss.

[0029] The present disclosure provides various techniques for avoiding partial display loss potentially caused by the failure of one or more light sources of a backlight device. In one or more embodiments, a display device includes a backlight device and a local dimming circuit. The backlight device includes a plurality of light sources configured to illuminate the display panel. The local dimming circuit is configured to individually control the brightness levels of the plurality of light sources based on first input image data in a first local dimming mode. The local dimming circuit is further configured to enter a failure mode in response to the failure of at least one of the light sources and control the brightness levels of the other light sources among the plurality of light sources to a predetermined brightness level in the failure mode. In one implementation, the predetermined brightness level may be the maximum allowable brightness level for the plurality of light sources. Detailed embodiments for avoiding partial display loss potentially caused by the failure of one or more light sources of a backlight device are described below.

[0030] Figure 1Shows an example configuration of a display device 1000 according to one or more embodiments. In the illustrated embodiment, the display device 1000 includes a display panel 100, a two-dimensional (2D) backlight device 200, a plurality of display drivers 300, a timing controller (TCON) 500, and a backlight driver 600. The display panel 100 may be a transmissive display panel, such as a liquid crystal display (LCD) panel. The 2D backlight device 200 is located behind the display panel 100 to illuminate the display panel 100. The 2D backlight device 200 includes an array of light sources 210 configured to illuminate corresponding regions of the display panel 100. In one implementation, each light source 210 may include a light emitting diode (LED) or other type of light source.

[0031] Figure 2 Shows an example arrangement of the light sources 210 of the backlight device 200 according to one or more embodiments. Hereinafter, directions may be indicated by the X-axis and the Y-axis, where the X-axis is oriented in the horizontal direction of the display panel 100, and the Y-axis is oriented in the vertical direction of the display panel 100. In the illustrated embodiment, the display panel 100 is divided into an array of regions 110, and the light sources 210 are arranged such that the projection of the corresponding light source 210 onto the display panel 100 is located at the center (e.g., geometric center) of the corresponding region 110. Since the light emitted from each light source 210 spreads as it travels, each light source 210 is configured to mainly illuminate the corresponding region 110, but also to illuminate the adjacent regions 110 surrounding the corresponding region 110 to a lesser extent. In one implementation, the regions 110 have a rectangular (e.g., square) shape and are arranged in rows and columns. In other implementations, the regions 110 may have different shapes, such as a rhombus shape and a hexagonal shape, as long as the regions 110 completely cover the display panel 100. Although 288 light sources 210 are shown in Figure 2 , those skilled in the art will appreciate that the 2D backlight device 200 may include more or fewer than 288 light sources 210. In a practical implementation, the 2D backlight device 200 may include from hundreds to thousands of light sources 210.

[0032] Returning to Figure 1 , the display driver 300 is configured to drive or update the display panel 100 under the control of the timing controller 500. In the illustrated embodiment, the display device 1000 includes three display drivers 300, the leftmost of which is configured to drive the left third of the display panel 100, the middle one is configured to drive the middle third, and the rightmost one is configured to drive the right third.

[0033] The timing controller 500 is configured to receive input image data from the host 2000 and control the display driver 300 to display an image corresponding to the input image data on the display panel 100. In one implementation, the input image data includes the gray levels of the corresponding pixels of the display panel 100. The host 2000 can be an application processor, a central processing unit (CPU), or any other type of processor configured to generate the input image data. The host may include non-transitory memory to store data. The timing controller 500 is further configured to provide timing control of the display driver 300 during the display of the image on the display panel 100. In some implementations, the timing controller 500 can be configured to provide horizontal and vertical synchronization to the display driver 300 to display a consistent image on the display panel 100.

[0034] In the illustrated embodiment, the timing controller 500 includes a local dimming circuit 550, which is configured to generate backlight data and provide the backlight data to the backlight driver 600 to implement a local dimming function of individually controlling the brightness levels of the light sources 210 of the 2D backlight device 200. In some implementations, the backlight data may include backlight values for the corresponding light sources 210, and the backlight driver 600 can be configured to control the light sources 210 based on the backlight data. In one implementation, the backlight value for the corresponding light source 210 can indicate a specified brightness level of the light source 210, and the backlight driver 600 can be configured to control the brightness level of the corresponding light source 210 as specified by the backlight value.

[0035] In some implementations, the local dimming circuit 550 can be further configured to process the input image data to generate processed image data and provide the processed image data to the display driver 300. In such an implementation, the display driver 300 can be configured to drive the display panel 100 based on the processed image data.

[0036] In one or more embodiments, the local dimming circuit 550 is further configured to implement a fail-safe function in the event of failure of one or more light sources 210. The local dimming circuit 550 is configured to enter a failure mode in response to the failure of at least one of the light sources 210. The local dimming circuit 550 is further configured to control the brightness levels of the other light sources 210 to a pre-determined sufficiently high brightness level in the failure mode such that the one or more zones 110 corresponding to the one or more failed light sources 210 are illuminated by the light sources 210 adjacent to the one or more failed light sources 210. This allows a user to visually perceive the portion of the image to be displayed in the one or more zones 110 corresponding to the one or more failed light sources 210, thereby avoiding partial display loss on the display panel 100. In one implementation, the pre-determined brightness level may be the maximum allowable brightness level for the light sources 210 that illuminates the one or more zones 110 corresponding to the one or more failed light sources 210 as brightly as possible by the adjacent light sources 210. In other implementations, the pre-determined brightness level may be different from the maximum allowable brightness level for the light sources 210.

[0037] To implement the fail-safe function, in some embodiments, the backlight driver 600 may be configured to detect the failure of one or more light sources 210 of the backlight device 200 and send a failure flag to the local dimming circuit 550 in response to detecting the failure. In such an embodiment, the local dimming circuit 550 may be configured to enter the failure mode in response to receiving the failure flag from the backlight driver 600. The backlight driver 600 may be further configured to send failure location data to the local dimming circuit 550. The failure location data may indicate the location or arrangement of the one or more failed light sources 210. In such an embodiment, the local dimming circuit 550 may be configured to enter the failure mode depending on the number of the one or more failed light sources 210. In one implementation, the local dimming circuit 550 may be configured to enter the failure mode in response to the number of failed light sources 210 exceeding a pre-determined threshold number. In an alternative embodiment, the backlight driver 600 may be configured to measure the current level of the respective light source 210 (i.e., the level of the current supplied to the respective light source 210) and provide light source current data indicating the current level of the respective light source 210. In such an embodiment, the local dimming circuit 550 may be configured to determine the number of the one or more failed light sources 210 based on the light source current data and enter the failure mode in response to the number of failed light sources 210 exceeding a pre-determined threshold number.

[0038] Figure 3Shows an example configuration of a local dimming circuit 550 according to one or more embodiments. In the illustrated embodiment, the local dimming circuit 550 is configured to receive input image data from a host 2000 (shown in Figure 1 ), and a failure flag from a backlight driver 600. The local dimming circuit 550 is configured to process the input image data to generate processed image data and further generate backlight data to control the brightness levels of the corresponding light sources 210 of the backlight device 200. In one or more embodiments, the local dimming circuit 550 includes an image analysis circuit 560, a mode control circuit 570, a backlight control circuit 580, and an image processing circuit 590.

[0039] The image analysis circuit 560 is configured to analyze the input image data to generate analysis data. In one implementation, the image analysis circuit 560 may be configured to calculate the average picture level (APL) of the corresponding region 110 of the display panel 100 based on the input image data, and the analysis data may include the APL of the corresponding region 110.

[0040] The mode control circuit 570 is configured to control the operation mode of the local dimming circuit 550 in response to a failure flag received from the backlight driver 600 (shown in Figure 1 ). In one or more embodiments, the mode control circuit 570 may be configured to place the local dimming circuit 550 in a local dimming mode in which the local dimming function is implemented in response to not receiving a failure flag. The mode control circuit 570 may be further configured to place the local dimming circuit 550 in a failure mode in which the local dimming function is stopped in response to receiving a failure flag from the backlight driver 600. The mode control circuit 570 may be further configured to generate a mode control signal for the backlight control circuit 580 and the image processing circuit 590 indicating the operation mode of the local dimming circuit 550 (e.g., local dimming mode, failure mode, or other operation modes (if any)).

[0041] The backlight control circuit 580 is configured to generate backlight data, which may include backlight values for controlling the brightness levels of the corresponding light sources 210. The generation of the backlight data is based on the operation mode informed by the mode control signal. When the mode control signal indicates that the local dimming circuit 550 is in the local dimming mode, the backlight control circuit 580 generates backlight data based on the analysis data received from the image analysis circuit 560 to implement the local dimming function. In an implementation in which the analysis data includes the APL of the corresponding region 110 of the display panel 100 and the backlight data includes the backlight value for the corresponding light source 210, the backlight control circuit 580 may be configured to determine the backlight value for the corresponding light source 210 based on the APL of the region 110 corresponding to the corresponding light source 210.

[0042] When the mode control signal indicates that the local dimming circuit 550 is in the failure mode, the backlight control circuit 580 stops the local dimming function and generates backlight data to control the non-failed light sources 210 (i.e., the light sources 210 other than the failed light source(s) 210) to a pre-determined sufficiently high brightness level. This allows the light sources 210 surrounding the failed light source(s) 210 to illuminate the zone(s) 110 corresponding to the failed light source(s) 210. In one implementation, when the local dimming circuit 550 is in the failure mode, the backlight control circuit 580 may determine the backlight value for the non-failed light sources 210 included in the backlight data as a value corresponding to the maximum allowable brightness level to cause the non-failed light sources 210 to emit light at the maximum allowable brightness level.

[0043] The image processing circuit 590 is configured to process the input image data based on the analysis data to generate processed image data. The processed image data is provided to the display driver 300, which is configured to drive the display panel 100 based on the processed image data. The image processing performed by the image processing circuit 590 may include gamma transformation. In one implementation, the gamma transformation may convert the input gray level into a gamma-transformed gray level for a corresponding pixel according to a gamma curve determined for the corresponding pixel based on the APL described in the analysis data. The gamma curve mentioned herein is a curve representing the correspondence between the input gray level and the gamma-transformed gray level in the gamma transformation. The input gray level of a corresponding pixel may be generated by performing desired processing (e.g., color adjustment, demura correction, deburn correction, image scaling, or other image processes) on the gray level of the corresponding pixel described in the input image data. In an alternative implementation, the gray level described in the input image data may be used as the input gray level without modification. The gamma-transformed gray level of a corresponding pixel is used to determine the gray level of the corresponding pixel described in the processed image data. In one implementation, the gamma-transformed gray level determined by the gamma transformation may be used as the gray level described in the processed image data without modification. In one or more embodiments, the gamma value of the gamma curve used for the gamma transformation may be determined for each pixel in each zone 110 based on the APL of that zone 110. It should be noted that, as is known in the art, the gamma value is a parameter that defines the shape of the gamma curve of interest. The processing performed by the image processing circuit 590 may also include various image processes other than the gamma transformation, such as color adjustment, demura correction, deburn correction, image scaling, or other image processes.

[0044] In one or more embodiments, the image processing circuit 590 may be further configured to determine a compensated gamma curve for pixels located in the one or more zones 110 corresponding to the one or more failed light sources 210 in response to the local dimming circuit 550 entering a failure mode, to increase the brightness level of the pixels in the zone 110. In such an embodiment, the image processing circuit 590 may be configured to perform a gamma transformation on the input gray levels of the pixels located in the one or more zones 110 corresponding to the one or more failed light sources 210 according to the compensated gamma curve.

[0045] Figure 4 FIG. shows an example of a compensated gamma curve determined for pixels located in the zone 110 corresponding to the failed light source 210 according to one or more embodiments. The solid curve indicates the compensated gamma curve, while the dashed curve indicates the original gamma curve determined based on the APL of the zone 110 corresponding to the failed light source 210 in the local dimming mode. The compensated gamma curve is determined such that the gamma value of the compensated gamma curve is less than the gamma value of the original gamma curve. In one implementation, the compensated gamma curve may be determined such that the gamma value of the compensated gamma curve is a predetermined value equal to or close to 1.0. However, it should be noted that the default gamma value of a common display device is 2.2, and a gamma value of 1.0 represents a linear correlation between the input gray level and the gamma-transformed gray level. The gamma value of the compensated gamma curve may be determined to be substantially less than 2.2. Using the compensated gamma curve determined in this way effectively increases the brightness level of the pixels located in the zone 110 corresponding to the failed light source 210.

[0046] Figure 5 is a flowchart of an example method 400 implementing a fail-safe function for avoiding partial display loss in the event of a failure of one or more light sources 210 according to one or more embodiments. It will be appreciated that any of the following steps may be performed in any suitable order, and method 400 may be performed in any suitable environment.

[0047] In some implementations, the host 2000 (shown in Figure 1 may have information about the failure of the light sources 210 of the backlight device 200 before the startup of the display device 1000. At the startup of the display device 1000, if the host 2000 realizes that one or more light sources 210 have failed, the host 2000 may send a backlight failure command to the local dimming circuit 550 of the timing controller 500. If the local dimming circuit 550 receives a backlight failure command from the host 2000 during startup in step 402 (i.e., if one or more light sources 210 have failed), the process proceeds to step 420.

[0048] In step 420, the local dimming circuit 550 enters a failure mode, thereby disabling the local dimming function. In addition, the backlight control circuit 580 of the local dimming circuit 550 adjusts the brightness level of the non-failed light sources 210 to a predetermined brightness level, such as 100% or the maximum allowable brightness level, through backlight data. In one implementation, the backlight control circuit 580 can determine the backlight value for the non-failed light sources 210 included in the backlight data as a value corresponding to the maximum allowable brightness level, so that the non-failed light sources 210 emit light at the maximum allowable brightness level. The process then goes to step 422.

[0049] In step 422, the image processing circuit 590 of the local dimming circuit 550 adjusts the gamma curve for gamma transformation for the pixels located in the (one or more) regions 110 corresponding to the (one or more) failed light sources 210. In one implementation, the image processing circuit 590 determines a compensated gamma curve for the pixels located in the (one or more) regions 110 corresponding to the (one or more) failed light sources 210 and performs gamma transformation for the pixels located in the (one or more) regions 110 corresponding to the (one or more) failed light sources 210 according to the compensated gamma curve. As discussed with respect to Figure 4 The compensated gamma curve can be determined such that the gamma value of the compensated gamma curve is a predetermined value equal to or close to 1.0 to increase the brightness level of the pixels located in the (one or more) regions 110 corresponding to the (one or more) failed light sources 210.

[0050] When the local dimming circuit 550 does not receive a backlight failure command during startup in step 402, the local dimming circuit 550 enters the local dimming mode in step 404. In the local dimming mode, the backlight control circuit 580 performs the local dimming function based on the analysis data received from the image analysis circuit 560 to individually control the brightness levels of the corresponding light sources 210 of the backlight device 200. The process then goes to step 406.

[0051] In step 406, the local dimming circuit 550 checks the status of the backlight device 200 based on whether the local dimming circuit 550 receives a failure flag from the backlight driver 600. As long as the local dimming circuit 550 does not receive a failure flag, the local dimming circuit 550 remains in the local dimming mode in step 410. As long as the local dimming circuit 550 remains in the local dimming mode, the local dimming circuit 550 can check the status of the backlight device 200 every predetermined number of frames. Alternatively, as long as the local dimming circuit 550 remains in the local dimming mode, the local dimming circuit 550 can check the status of the backlight device 200 at a predetermined time interval and / or periodically.

[0052] When one or more of the light sources 210 fail during operation, the backlight driver 600 sends a failure flag to the local dimming circuit 550 in step 408, and the process goes to step 430.

[0053] In step 430, the local dimming circuit 550 enters a failure mode, thereby disabling the local dimming function. Additionally, the backlight control circuit 580 of the local dimming circuit 550 adjusts the brightness level of the non-failed light sources 210 to a predetermined brightness level (e.g., 100% or the maximum allowable brightness level) via backlight data as in step 420. The process then goes to step 432.

[0054] In step 432, the image processing circuit 590 of the local dimming circuit 550 adjusts the gamma curve for gamma transformation for the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210 as in step 422. In one implementation, the image processing circuit 590 determines a compensated gamma curve for the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210 and performs gamma transformation for the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210 according to the compensated gamma curve. As discussed with respect to step 422, the compensated gamma curve can be determined such that the gamma value of the compensated gamma curve is a predetermined value equal to or close to 1.0 to increase the brightness level of the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210. The process then goes to step 434.

[0055] In step 434, the local dimming circuit 550 sends a backlight failure command to the host 2000 to thereby notify the host 2000 of the failure of one or more of the light sources 210. This makes the host 2000 aware of the failure of one or more of the light sources 210. At the next startup of the display device 1000, the host 2000 can send a backlight failure command to the local dimming circuit 550 to notify the local dimming circuit 550 of the failure of one or more of the light sources 210.

[0056] Figure 6 An example configuration of a display device 3000 according to other embodiments is shown. In the illustrated embodiment, the local dimming circuit 1350 is integrated into a display driver 1300 configured to drive the display panel 100. The local dimming circuit 1350 can be associated with Figure 1 and Figure 3The local dimming circuit 550 shown in [reference] is similarly configured and can operate similarly to the local dimming circuit 550. The local dimming circuit 1350 can be configured to generate backlight data and provide the backlight data to the backlight driver 600. The local dimming circuit 1350 can be further configured to provide the processed image data to the driver circuit 1360. The driver circuit 1360 can be configured to drive the display panel 100 based on the processed image data.

[0057] Although Figure 5 the method 400 shown in [reference] disables the local dimming function in response to the failure of one or more light sources, the present disclosure recognizes that, particularly in embodiments where the light sources 210 are spaced relatively closely, the failure of a small number of light sources 210 (e.g., one light source 210) can be compensated for by increasing the brightness level of the light sources 210 adjacent to the failed light source. In embodiments where the failure of a small number of light sources 210 is compensated for by increasing the brightness level of the adjacent light sources 210, the local dimming function can be achieved regardless of the occurrence of such light source failures.

[0058] Figure 7A shows an example of light source failure compensation according to one or more embodiments. In the example shown, one light source 210 indicated by diagonal cross-hatching is experiencing failure. In this case, in one or more embodiments, the failure of the light source 210 can be compensated for by increasing the brightness level of the eight light sources 210 adjacent to the failed light source 210. The light sources 210 used for compensation are indicated by Figure 7A vertical and horizontal hatching in [reference].

[0059] Figure 7B shows another example of light source failure compensation according to one or more embodiments. In the example shown, four light sources indicated by diagonal cross-hatching are experiencing failure. Again in this case, the failure of the four light sources can be compensated for by increasing the brightness level of the nineteen light sources adjacent to the four failed light sources. The light sources used for compensation are indicated by Figure 7B vertical and horizontal hatching in [reference].

[0060] In one implementation, the brightness level of a light source 210 adjacent to at least one failed light source 210 can be controlled as follows. First, a basic backlight value for each light source 210 can be determined based on input image data. In one implementation, the basic backlight value for each light source 210 can be determined based on the APL of the region corresponding to that region. Note that the APL for each region can be calculated based on the input image data. This is then followed by determining a compensated backlight value for the light sources 210 adjacent to at least one failed light source 210 based on the basic backlight value for the light sources 210 adjacent to the failed light source 210 and failure location data, where the failure location data indicates the location or arrangement of at least one failed light source 210. The compensated backlight value for the light sources 210 adjacent to at least one failed light source 210 can be determined by modifying the basic backlight value of the adjacent light sources 210 based on the failure location data. In one implementation, a compensation coefficient indicating the amount by which the brightness level of the adjacent light sources 210 is to be increased is determined based on the failure location data, and the compensated backlight value of the adjacent light sources 210 can be determined by applying the compensation coefficient to the corresponding basic backlight values of the adjacent light sources 210. The compensated backlight value of the light sources 210 adjacent to the failed light source 210 can indicate the specified brightness level of the adjacent light sources 210. The light sources 210 adjacent to the failed light source 210 can be controlled based on the compensated backlight value determined for those adjacent light sources 210.

[0061] Figure 8A FIG. shows an example configuration of a local dimming circuit 1550 configured to compensate for the failure of one or more light sources 210 by increasing the brightness level of the light sources 210 adjacent to the failed light source 210. The local dimming circuit 1550 can be Figure 1 an embodiment of the local dimming circuit 550 shown in Figure 6 or an embodiment of the local dimming circuit 1350 shown in Figure 8A In the embodiment shown in Figure 1 the local dimming circuit 1550 is configured to receive input image data from a host 2000 (shown in

[0062] The image analysis circuit 1560 is configured to operate in a manner related to Figure 3Analyzes the input image data in a manner similar to the described image analysis circuit 560 to generate analysis data. In one implementation, the image analysis circuit 1560 may be configured to calculate the APL of the corresponding region 110 of the display panel 100 based on the input image data, and the analysis data may include the APL of the corresponding region 110.

[0063] The mode control circuit 1570 is configured to control the operation mode of the local dimming circuit 1550 in response to the failure flag and the failure location data received from the backlight driver 600 (shown in Figure 1 ). As described above, the failure location data may indicate the location or arrangement of the failed light source(s) 210. In one or more embodiments, the mode control circuit 1570 may be configured to determine the number of failed light sources 210 based on the failure flag and the failure location data. The mode control circuit 1570 may further be configured to place the local dimming circuit 1550 in a local dimming mode in which the local dimming function is implemented when the light source 210 does not experience a failure. The mode control circuit 1570 may further be configured to place the local dimming circuit 1550 in a failure mode when the number of failed light sources 210 is greater than a predetermined threshold number. The mode control circuit 1570 may further be configured to place the local dimming circuit 1550 in a "second" local dimming mode when the number of failed light sources 210 is non-zero and less than a predetermined threshold number. The "second" local dimming mode is an operation mode in which the local dimming function is enabled while compensating for the failure of the light source(s) 210 by increasing the brightness level of the light source(s) 210 adjacent to the failed light source(s) 210. The mode control circuit 1570 is configured to notify the image processing circuit 1590 and the backlight control circuit 1580 of the operation mode of the local dimming circuit 1550 through a mode control signal.

[0064] The image processing circuit 1590 is configured to process the input image data based on the analysis data received from the image analysis circuit 1560 in a manner similar to the described image processing circuit 590 to generate processed image data. The processed image data may be provided to the display driver 300 (in Figure 3 ). Figure 1As shown in FIG. 300, the display driver 300 is configured to drive the display panel 100 based on the processed image data. The image processing performed by the image processing circuit 1590 may include gamma transformation. In one implementation, the gamma transformation may convert the input gray level into a gamma-transformed gray level for a corresponding pixel according to a gamma curve determined for the corresponding pixel based on the APL described in the analysis data. The input gray level of the corresponding pixel may be generated by performing desired processing on the gray level described in the input image data. The gamma-transformed gray level of the corresponding pixel is used to determine the gray level of the corresponding pixel described in the processed image data. The gamma-transformed gray level determined by the gamma transformation may be used as the gray level described in the processed image data without modification. Details of determining the gamma curve will be described in detail later. The processing performed by the image processing circuit 1590 may also include various image processes other than gamma transformation, such as color adjustment, non-uniformity correction, burn-in correction, image scaling, or other image processes.

[0065] In one or more embodiments, as described with respect to Figure 4 FIG. 1590, the image processing circuit may be further configured to determine a compensated gamma curve for pixels located in the one or more regions 110 corresponding to the one or more failed light sources 210 in response to the local dimming circuit 1550 entering a failure mode, in order to increase the brightness level of the pixels in the region 110. In such an embodiment, the image processing circuit 1590 may be configured to perform gamma transformation on the input gray levels of the pixels located in the one or more regions 110 corresponding to the one or more failed light sources 210 according to the compensated gamma curve.

[0066] The compensation coefficient determination circuit 1600 is configured to generate compensation coefficient data based on the failure location data received from the backlight driver 600 (shown in Figure 1 FIG. 6). As discussed with respect to Figure 1 FIG. 6, the failure location data may indicate the location or arrangement of the one or more failed light sources 210. The compensation coefficient data includes a compensation coefficient indicating the amount by which the brightness level of the light sources 210 adjacent to the one or more failed light sources 210 is to be increased. In one implementation, the compensation coefficient for the light sources 210 adjacent to the one or more failed light sources 210 may be determined as a non-zero value. The compensation coefficient for the light sources 210 that are not adjacent to any of the one or more failed light sources 210 may be determined as zero.

[0067] The backlight control circuit 1580 is configured to generate backlight data based on the analysis data received from the image analysis circuit 1560 and the compensation coefficient data received from the compensation coefficient determination circuit 1600. Figure 8BShows an example configuration of a backlight control circuit 1580 according to one or more embodiments. In the illustrated embodiment, the backlight control circuit 1580 includes a compensation factor lookup table (LUT) 1582, a basic backlight data arithmetic circuit 1584, and a backlight data compensation circuit 1586.

[0068] The compensation factor LUT 1582 is configured to store compensation factor data received from a compensation factor determination circuit 1600. As described above, the compensation factor data includes compensation factors determined for corresponding light sources 210. The compensation factor LUT 1582 is configured to provide the stored compensation factor data to the backlight data compensation circuit 1586. For example, the compensation factor LUT 1582 may be configured such that the compensation factors determined for corresponding light sources 210 can be addressed by the coordinates of the corresponding light sources 210 indicated by "(X, Y)" in Figure 8B the.

[0069] The basic backlight data arithmetic circuit 1584 is configured to generate basic backlight data based on analysis data received from an image analysis circuit 1560 (shown in Figure 8A ). The basic backlight data includes basic backlight values calculated for corresponding light sources 210. In an embodiment where the analysis data includes the APL of the corresponding region 110, the basic backlight data arithmetic circuit 1584 may be configured to calculate the basic backlight value for the corresponding light source 210 based on the APL of the region 110 corresponding to the corresponding light source 210. The basic backlight data arithmetic circuit 1584 is further configured to provide the thus generated basic backlight data to the backlight data compensation circuit 1586.

[0070] The backlight data compensation circuit 1586 is configured to generate backlight data by modifying the basic backlight data received from the basic backlight data arithmetic circuit 1584 based on the compensation factor data received from the compensation factor LUT 1582. The backlight data may include compensated backlight values for corresponding light sources 210. Since the compensation values for light sources 210 not adjacent to a failed light source 210 are zero, the compensated backlight values for light sources 210 not adjacent to a failed light source 210 are equal to the basic backlight values for those light sources 210. At the same time, the compensated backlight values for light sources 210 adjacent to at least one failed light source 210 are generated by modifying the basic backlight values for those adjacent light sources 210 based on the compensation factors determined for those light sources 210. In one implementation, the backlight data, which may include the compensated backlight values, is provided to a backlight driver 600 to control the brightness level of the corresponding light sources 210. The compensated backlight value for a corresponding light source 210 may indicate a specified brightness level for the corresponding light source 210, and the brightness level of the corresponding light source 210 may be controlled based on the compensated backlight value for the corresponding light source 210.

[0071] Figure 9 Illustrates an example method 900 for implementing a fail-safe function according to one or more embodiments, the fail-safe function being used to avoid partial display loss in the event of a failure of one or more light sources 210, while compensating for the failure of one or more light sources 210 by increasing the brightness level of the light sources 210 adjacent to the failed light source 210. It will be recognized that, unless otherwise obvious, the following steps may be performed in any suitable order, and method 900 may be performed in any suitable environment.

[0072] As described with respect to Figure 5 and shown in Figure 1 the host 2000 may have information regarding the failure of the light sources 210 of the backlight device 200 prior to the startup of the display device 1000. When the display device 1000 starts up, if the host 2000 realizes that one or more light sources 210 have failed, the host 2000 may send a backlight failure command to the local dimming circuit 1550.

[0073] When the local dimming circuit 1550 does not receive a backlight failure command during startup in step 902, the local dimming circuit 1550 enters a first local dimming mode in step 904. Note that the first local dimming mode is an operating mode in which the local dimming function is implemented, but the compensation for light source failure is not performed. The backlight control circuit 1580 implements the local dimming function in the first local dimming mode based on the analysis data received from the image analysis circuit 1560 to individually control the brightness levels of the respective light sources 210 of the backlight device 200. The process then goes to step 906.

[0074] In step 906, the local dimming circuit 1550 checks the status of the backlight device 200 based on whether the local dimming circuit 1550 receives a failure flag from the backlight driver 600. As long as the local dimming circuit 1550 does not receive a failure flag, the local dimming circuit 1550 remains in the first local dimming mode in step 910. As long as the local dimming circuit 1550 remains in the first local dimming mode, the local dimming circuit 1550 may check the status of the backlight device 200 every pre-determined number of frames.

[0075] When a failure of one or more light sources 210 occurs during operation, the backlight driver 600 sends a failure flag to the local dimming circuit 1550 in step 908, and the process goes to step 930.

[0076] In step 930, the local dimming circuit 1550 enters a failure mode, thereby disabling the local dimming function. Additionally, the backlight control circuit 1580 of the local dimming circuit 1550 adjusts the brightness level of the non-failed light sources 210 to a predetermined brightness level (e.g., 100% or the maximum allowable brightness level) via backlight data. The process then proceeds to step 932.

[0077] In step 932, the image processing circuit 1590 of the local dimming circuit 1550 adjusts the gamma curve for gamma transformation for the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210 as in steps 422 and 432 described with respect to Figure 5 In one implementation, the image processing circuit 1590 determines a compensated gamma curve for the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210 and performs gamma transformation for the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210 according to the compensated gamma curve. As discussed with respect to step 422 as shown in Figure 5 The compensated gamma curve can be determined such that the gamma value of the compensated gamma curve is a predetermined value equal to or close to 1.0 to increase the brightness level of the pixels located in the (one or more) zones 110 corresponding to the (one or more) failed light sources 210. The process then proceeds to step 934.

[0078] In step 934, the local dimming circuit 1550 sends a backlight failure command to the host 2000 to thereby notify the host 2000 of the failure of one or more of the light sources 210. This makes the host 2000 aware of the failure of one or more of the light sources 210. At the next startup of the display device, the host 2000 can send a backlight failure command to the local dimming circuit 1550 to notify the local dimming circuit 550 of the failure of one or more of the light sources 210.

[0079] If the local dimming circuit 1550 receives a backlight failure command during startup in step 902 (e.g., if one or more of the light sources 210 have failed), the process proceeds to step 920.

[0080] In step 920, the local dimming circuit 1550 disables the local dimming function. Additionally, the backlight control circuit 1580 of the local dimming circuit 1550 adjusts the brightness level of the non-failed light sources 210 to a predetermined brightness level, such as 100% or the maximum allowable brightness level, through the backlight data. In one implementation, the backlight control circuit 1580 may determine the backlight value for the non-failed light sources 210 included in the backlight data as a value corresponding to the maximum allowable brightness level, so that the non-failed light sources 210 emit light at the maximum allowable brightness level. The process then proceeds to step 922.

[0081] In step 922, the local dimming circuit 1550 retrieves the failure location data from the backlight driver 600. Note that the failure location data may indicate the location or arrangement of the failed light source(s) 210. The process then proceeds to step 924.

[0082] In step 924, the mode control circuit 1570 of the local dimming circuit 1550 determines the number of failed light sources 210 based on the failure location data. If the number of failed light sources 210 is greater than or equal to a predetermined threshold number, the local dimming circuit 1550 enters the failure mode, and the process proceeds to step 930. If the number of failed light sources 210 is less than the predetermined threshold number, the process proceeds to step 926.

[0083] In step 926, the compensation coefficient determination circuit 1600 determines the compensation coefficient for the corresponding light sources 210 based on the failure location data, which may indicate the location or arrangement of the failed light source(s) 210. In one implementation, the compensation coefficient for the light sources 210 adjacent to at least one failed light source 210 may be determined as a non-zero value. The compensation coefficient for the light sources 210 not adjacent to the failed light source 210 may be determined as zero. The determined compensation coefficients are provided to the backlight control circuit 1580 and stored in the compensation coefficient LUT 1582 of the backlight control circuit 1580. The process then proceeds to step 928.

[0084] In step 928, the local dimming circuit 1550 enters the second local dimming mode. Note that the second local dimming mode is an operating mode in which the local dimming function is implemented using light source failure compensation. In the second local dimming mode, the backlight data compensation circuit 1586 of the backlight control circuit 1580 generates the compensated backlight value for the corresponding light sources 210 by modifying the basic backlight value for the corresponding light sources 210 based on the compensation coefficient for the corresponding light sources 210. The compensated backlight value for the corresponding light sources 210 is provided to the backlight driver 600, and the backlight driver 600 controls the brightness level of the corresponding light sources 210 based on the compensated backlight value for the corresponding light sources 210.

[0085] As long as the number of failed light sources 210 is less than a predetermined threshold number, the steps 922, 924, 926, and 928 described above can be repeated every predetermined number of frames.

[0086] As described above, the gamma transformation performed by the image processing circuit 1590 (shown in Figure 8A ) can be based on a gamma curve that is determined for a corresponding pixel based on the APL described in the analysis data generated by the image analysis circuit 1560. Figure 10 An example of the APL of the corresponding region 110 of the display panel 100 according to one or more embodiments is shown. In Figure 10 , APL(i, j) indicates the APL of the region 110 in the (i + 1)-th row from the top and the (j + 1)-th column from the left, where i is a natural number between 0 and M - 1 (including 0 and M - 1), and j is a natural number between 0 and N - 1 (including 0 and N - 1). The following describes an example method for determining the gamma value of the gamma curve for gamma transformation for a corresponding pixel according to one or more embodiments.

[0087] Referring to Figure 11 , the black circles, shaded circles, and white circles indicate the corners of the corresponding region 110, which are hereinafter referred to as "region corners". In the embodiment shown in Figure 11 , the region corners are arranged in M + 2 rows and N + 2 columns on the display panel 100. In one or more embodiments, the image processing circuit 1590 may be configured to calculate the "region corner APL" for the corresponding region corner from the APL of the corresponding region 110. The "region corner APL" of a region corner represents the APL of the region surrounding the region corner. In the embodiment shown in Figure 11 , APL_corner(i, j) indicates the region corner APL of the region corner in the (i + 1)-th row from the top and the (j + 1)-th column from the left, where i is a natural number between 0 and M (including 0 and M), and j is a natural number between 0 and N (including 0 and N).

[0088] It should be noted that the region corners not located at the four corners of the display panel 100 are shared by multiple regions 110 (more specifically, two or four regions 110). In one implementation, the region corner APL of the region corner of interest not located at the four corners of the display panel 100 is determined as the average of the APLs of the corresponding regions 110 sharing the region corner of interest. At the same time, the region corner APL of the region corner located at each corner of the display panel 100 is determined to be equal to the APL of the region 110 at that corner of the display panel 100.

[0089] More specifically, in one or more embodiments, "zone corners" can be classified into the following three types: (1) zone corners located at the corners of the display panel 100, indicated by white circles; (2) zone corners located at the edges of the display panel 100, indicated by shaded circles; and (3) other zone corners, indicated by black circles, and the determination of the zone corner APL for the corresponding zone corner can depend on the corresponding zone corner type, as described below.

[0090] (1) Zone corners located at the corners of the display panel The zone corner APL for the zone corners located at the four corners of the display panel 100 can be determined according to the following expressions (1a) to (1d): APL_corner(0, 0) = APL(0, 0), (1a) APL_corner(0, N + 1) = APL(0, N), (1b) APL_corner(M + 1, 0) = APL(M, 0), and (1c) APL_corner(M + 1, N + 1) = APL(M, N). (1d)

[0091] (2) Zone corners located at the edges of the display panel The zone corner APL for the zone corners located at the four edges of the display panel 100 can be determined according to the following expressions (2a) to (2d): APL_corner(0, q) = {APL(0, q - 1) + APL(0, q)} / 2, (2a) APL_corner(p, 0) = {APL(p - 1, 0) + APL(p, 0)} / 2, (2b) APL_corner(M + 1, q) = {APL(M, q - 1) + APL(M, q)} / 2, and (2c) APL_corner(p, N + 1) = {APL(p - 1, N) + APL(p, N)} / 2, (2d) where p is a natural number between 1 and M (including 1 and M), and q is a natural number between 1 and N (including 1 and N).

[0092] (3) Other zone corners located at the edges of the display panel The zone corner APL for the other zone corners located in the inner part of the display panel 100 can be determined according to the following expression (3): APL_corner(p, q) = {APL(p - 1, q - 1) + APL(p - 1, q) + APL(p, q - 1) + APL(p, q)} / 4. (3)

[0093] In one or more embodiments, the image processing circuit 1590 may be further configured to calculate a "pixel APL" for a corresponding pixel from region corner APLs at the corners of the corresponding region. The pixel APL for a pixel represents the APL of the region surrounding the pixel. In one implementation, the pixel APL for a pixel located in region 110 is calculated by interpolating the region corner APLs determined for the corners of region 110 depending on the positioning of the pixels in region 110.

[0094] Figure 12 FIG. shows an example calculation of the pixel APL for pixel 120 in region 110 located in the (i + 1)-th row and (j + 1)-th column according to one or more embodiments, where i is a natural number between 0 and M (including 0 and M), j is a natural number between 0 and N (including 0 and N), and (x, y) are the X and Y coordinates of pixel 120. In the illustrated embodiment, the region corner APLs determined for the corners of region 110 are APL_corner(i, j), APL_corner(i, j + 1), APL_corner(i + 1, j), and APL_corner(i + 1, j + 1), respectively. In one or more embodiments, the pixel APL for pixel 120 located at (x, y) may be calculated according to the following expression (4): where APL_pixel(x, y) is the pixel APL of pixel 120 at (x, y), and s and t are parameters defined by the following expressions (5a) and (5b): s = x - X_region·j, (5a) t = y - Y_region·i, (5b) X 区 is the horizontal width of each region 110, and Y 区 is the vertical height of each region 110. The pixel APL for each pixel of the display panel 100 may be calculated according to expression (4).

[0095] Reference Figure 13 , in one or more embodiments, the gamma value of the gamma curve for gamma transformation for each pixel may be determined based on the pixel APL calculated for the pixel. In one implementation, the gamma value of the gamma curve for gamma transformation for each pixel increases as the pixel APL of the pixel increases. In other words, the smaller the pixel APL of the pixel of interest, the smaller the gamma value of the gamma curve for gamma transformation for the pixel. Although Figure 13It is shown that the gamma curve for gamma transformation increases linearly with the pixel APL, but the gamma curve for gamma transformation can increase non-linearly with the pixel APL. The image processing circuit 1590 may be configured to perform gamma transformation on the input gray level of each pixel according to the gamma curve defined by the gamma value determined based on the pixel APL of the pixel.

[0096] In one or more embodiments, the image processing circuit 1590 may be further configured to adjust the gamma curve for the pixels located in the (one or more) regions 110 corresponding to the (one or more) failed light sources 210 in the second local dimming mode to increase the brightness level of the pixels located in the (one or more) regions 110. Refer to Figure 14 , the adjustment of the gamma curve for the pixels located in the region 110 corresponding to the failed light source 210 can be completed by defining a predetermined assumed APL for the region 110 corresponding to the failed light source 210 and using the assumed APL to calculate the region corner APL and the pixel APL instead of the APL of the region 110 calculated from the input image data. This results in the gamma value of the gamma curve for gamma transformation for the pixels located in the region 110 corresponding to the failed light source 210 being determined based on the assumed APL. In such an embodiment, the smaller the assumed APL, the smaller the gamma value of the gamma curve for gamma transformation for the pixels located in the region 110 corresponding to the failed light source 210. Accordingly, the brightness level of the pixels located in the region 110 corresponding to the failed light source 210 can be increased by setting the assumed APL to a small value (such as zero). In one implementation, the assumed APL may be zero. In Figure 14 the embodiment shown in, where the light source 210 corresponding to the region 110 in the second row and the third column is assumed to have failed, the APL(1, 2) of the region 110 is set to 0.0 regardless of the input image data. This will increase the brightness level of the pixels located in the region 110 to compensate for the failure of the light source 210 corresponding to the region 110.

[0097] In other embodiments, the adjustment of the gamma curve for pixels located in region 110 corresponding to the failed light source 210 can be accomplished by modifying the APL of region 110 corresponding to the failed light source 210 and using the modified APL to calculate the region corner APL and pixel APL instead of the APL of region 110 calculated from the input image data. This results in the gamma value of the gamma curve for gamma transformation for pixels located in region 110 corresponding to the failed light source 210 being determined based on the modified APL. In such an embodiment, the smaller the modified APL, the smaller the gamma value of the gamma curve for gamma transformation for pixels located in region 110 corresponding to the failed light source 210. Accordingly, the brightness level of pixels located in region 110 corresponding to the failed light source 210 can be increased by determining the modified APL to be less than the APL of region 110 corresponding to the failed light source 210 calculated based on the input image data. In one implementation, the modified APL can be calculated by subtracting a positive value from the APL of region 110 corresponding to the failed light source 210.

[0098] Unless otherwise indicated herein or clearly contradicted by context, the terms "a", "an", "the", and "at least one", and similar referents used in the context of describing the present invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural. Unless otherwise indicated herein or clearly contradicted by context, the phrase "at least one" followed by a list of one or more items (e.g., "at least one of A and B") is to be construed to mean either one item (A or B) selected from the listed items or any combination of two or more of the listed items (A and B). Unless otherwise noted, the terms "comprising", "having", "including", and "containing" are to be construed as open terms (i.e., meaning "including but not limited to"). Unless otherwise indicated herein, the recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein. Unless otherwise indicated herein or otherwise clearly contradicted by context, all methods described herein can be performed in any suitable order. Unless otherwise required, any and all examples or exemplary language (e.g., "such as") used herein are merely intended to better illustrate the invention and do not pose a limitation on the scope of the invention. The language of the specification should not be construed as indicating any non-claimed element as essential for the practice of the invention.

[0099] Exemplary embodiments are described herein. Variations of those exemplary embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect those skilled in the art to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, the invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. In addition, unless otherwise indicated herein or otherwise clearly contradicted by context, the invention includes any combination of the elements described above in all possible variations thereof.

Claims

1. A display device, comprising: a backlight device comprising a plurality of light sources configured to illuminate the display panel; A local dimming circuit configured to: individually controlling brightness levels of the plurality of light sources based on first input image data in a first local dimming mode; entering a failure mode in response to a failure of at least one of the plurality of light sources; as well as In the failure mode, brightness levels of other light sources among the plurality of light sources are controlled to predetermined brightness levels.

2. The display device according to claim 1, wherein: The predetermined brightness level is a maximum allowed brightness level for the plurality of light sources.

3. The display device according to claim 1, wherein: The local dimming circuit is further configured to: In response to the local dimming circuit entering the failure mode, determining a compensated gamma curve for pixels in a zone corresponding to a failed light source among the plurality of light sources to increase brightness levels of the pixels in the zone; as well as In the failure mode, gamma transformation is performed on second input image data to generate second output image data for driving the display panel, wherein gamma transformation of pixel data for pixels in the area corresponding to the failed light source among the plurality of light sources is based on the compensated gamma curve.

4. The display device according to claim 1, wherein: The local dimming circuit is further configured to: entering a second local dimming mode in response to a number of failed light sources among the plurality of light sources being non-zero and less than a predetermined number; In the second local dimming mode, determining a basic backlight value for the corresponding light source based on the second input image data, wherein the basic backlight value for the corresponding light source comprises: a first base backlight value for a failed one of the light sources; and for a second basic backlight value of an adjacent light source among the light sources, the adjacent light source among the light sources being adjacent to the failed light source among the light sources; determining a compensated backlight value for the adjacent one of the light sources based on the second base backlight value and an arrangement of the failed one of the plurality of light sources; and A brightness level of the adjacent ones of the light sources is controlled based on the compensated backlight value.

5. The display device according to claim 4, wherein: Determining the compensated backlight value includes modifying the second base backlight value based on the first base backlight value to increase the brightness level of the adjacent ones of the light sources.

6. The display device according to claim 1, wherein: The local dimming circuit is further configured to: entering a second local dimming mode in response to a number of failed light sources in the plurality of light sources being non-zero and less than a predetermined threshold number; In the second local dimming mode, calculating a first average picture level (APL) of a first area corresponding to a non-failed light source among the light sources based on second input image data; determining a first gamma curve for a first pixel in the first zone based on the first APL; performing a gamma transformation on a first gray level of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma-transformed gray level for driving the first pixel; defining a predetermined assumed APL for a second zone corresponding to a failed one of the light sources; determining a second gamma curve for second pixels in the second region based on the predetermined assumed APL; as well as A second gray level of the second pixel described in the second input image data is gamma-converted based on the second gamma curve to determine a second gamma-converted gray level for driving the second pixel.

7. The display device according to claim 6, wherein: The smaller the first APL is, the smaller the first gamma value of the first gamma curve is, and Wherein the predetermined assumed APL is zero.

8. The display device according to claim 1, wherein: The local dimming circuit is further configured to: entering a second local dimming mode in response to a number of failed light sources among the plurality of light sources being non-zero and less than a predetermined number; In the second local dimming mode, calculating a first APL of a first zone corresponding to a non-failed light source among the light sources based on second input image data; determining a first gamma curve for a first pixel in the first zone based on the first APL; performing a gamma transformation on a first gray level of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma-transformed gray level for driving the first pixel; calculating a second APL of a second area corresponding to a failed light source among the light sources based on second input image data; determining the modified APL for the second zone by modifying the second APL so that the modified APL is less than the second APL; determining a second gamma curve for second pixels in the second region based on the modified APL; as well as A second gray level of the second pixel described in the second input image data is gamma-converted based on the second gamma curve to determine a second gamma-converted gray level for driving the second pixel.

9. The display device according to claim 8, wherein: the modified APL for the second zone is determined to be less than the second APL, The smaller the first APL is, the smaller the first gamma value of the first gamma curve is, and The smaller the modified APL is, the smaller the second gamma value of the second gamma curve is.

10. A display driver comprising: A local dimming circuit configured to: individually controlling brightness levels of a plurality of light sources of a backlight arrangement based on first input image data in a first local dimming mode, wherein the plurality of light sources are configured to illuminate a display panel; entering a failure mode in response to a failure of at least one of the plurality of light sources; as well as controlling the brightness levels of other light sources among the plurality of light sources to predetermined brightness levels in the failure mode; as well as A driver circuit is configured to drive the display panel based on the first input image data.

11. The display driver according to claim 10, wherein: The predetermined brightness level is a maximum allowed brightness level for the plurality of light sources.

12. The display driver according to claim 10, wherein: The local dimming circuit is further configured to: In response to the local dimming circuit entering the failure mode, determining a compensated gamma curve for pixels in a zone corresponding to a failed light source among the plurality of light sources to increase brightness levels of the pixels in the zone; as well as In the failure mode, gamma transformation is performed on second input image data to generate second output image data for driving the display panel, wherein gamma transformation of pixel data for pixels in the area corresponding to the failed light source among the plurality of light sources is based on the compensated gamma curve.

13. The display driver according to claim 10, wherein: The local dimming circuit is further configured to: entering a second local dimming mode in response to a number of failed light sources in the plurality of light sources being non-zero and less than a predetermined threshold number; In the second local dimming mode, determining a basic backlight value for the corresponding light source based on the second input image data, wherein the basic backlight value for the corresponding light source comprises: a first base backlight value for a failed one of the light sources; and for a second basic backlight value of an adjacent light source among the light sources, the adjacent light source among the light sources being adjacent to the failed light source among the light sources; determining a compensated backlight value for the adjacent one of the light sources based on the second base backlight value and an arrangement of the failed one of the plurality of light sources; and A brightness level of the adjacent ones of the light sources is controlled based on the compensated backlight value.

14. The display driver according to claim 13, wherein: Determining the compensated backlight value includes modifying the second base backlight value based on the first base backlight value to increase the brightness level of the adjacent ones of the light sources.

15. The display driver according to claim 10, wherein: The local dimming circuit is further configured to: entering a second local dimming mode in response to a number of failed light sources among the plurality of light sources being non-zero and less than a predetermined number; In the second local dimming mode, calculating a first average picture level (APL) of a first area corresponding to a non-failed light source among the light sources based on second input image data; determining a first gamma curve for a first pixel in the first zone based on the first APL; performing a gamma transformation on a first gray level of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma-transformed gray level for driving the first pixel; defining a predetermined assumed APL for a second zone corresponding to a failed one of the light sources; determining a second gamma curve for second pixels in the second region based on the predetermined assumed APL; as well as A second gray level of the second pixel described in the second input image data is gamma-converted based on the second gamma curve to determine a second gamma-converted gray level for driving the second pixel.

16. The display driver according to claim 15, wherein: The smaller the first APL is, the smaller the first gamma value of the first gamma curve is, and Wherein the predetermined assumed APL is zero.

17. The display driver according to claim 10, wherein: The local dimming circuit is further configured to: entering a second local dimming mode in response to a number of failed light sources among the plurality of light sources being non-zero and less than a predetermined number; In the second local dimming mode, calculating a first APL of a first zone corresponding to a non-failed light source among the light sources based on second input image data; determining a first gamma curve for a first pixel in the first zone based on the first APL; performing gamma conversion on a first gray level of the first pixel described in the second input image data based on the first gamma curve to generate a first gamma-converted gray level for driving the first pixel; calculating a second APL of a second area corresponding to a failed light source among the light sources based on second input image data; determining the modified APL for the second zone by modifying the second APL so that the modified APL is less than the second APL; determining a second gamma curve for second pixels in the second region based on the modified APL; as well as Gamma conversion is performed on a second gray level of the second input image data based on the second gamma curve to determine a second gamma-converted gray level for driving the second pixel.

18. A method comprising: placing the local dimming circuit in a first local dimming mode; controlling, by the local dimming circuit in the first local dimming mode, brightness levels of a plurality of light sources of a backlight device individually based on first input image data, wherein the plurality of light sources are configured to illuminate a display panel; placing the local dimming circuit in a failure mode in response to a failure of at least one of the plurality of light sources; as well as The brightness levels of other light sources among the plurality of light sources are controlled to predetermined brightness levels by the local dimming circuit in the failure mode.

19. The method according to claim 18, further comprising: determining, by the local dimming circuit in the failure mode, a compensated gamma curve for pixels in a zone corresponding to a failed light source among the plurality of light sources to increase brightness levels of the pixels in the zone; as well as The local dimming circuit in the failure mode performs gamma transformation on second input image data to generate second output image data for driving the display panel, wherein the gamma transformation of pixel data for pixels in the zone corresponding to the failed light source among the multiple light sources is based on the compensated gamma curve.

20. The method according to claim 18, wherein: The local dimming circuit is further configured to: placing the local dimming circuit into a second local dimming mode in response to a number of failed light sources in the plurality of light sources being non-zero and less than a predetermined threshold number; determining a basic backlight value for the corresponding light source based on the second input image data, wherein the basic backlight value for the corresponding light source comprises: a first base backlight value for a failed one of the light sources; and for a second basic backlight value of an adjacent light source among the light sources, the adjacent light source among the light sources being adjacent to the failed light source among the light sources; determining a compensated backlight value for the adjacent one of the light sources based on the second base backlight value and an arrangement of the failed one of the plurality of light sources; and A brightness level of the adjacent ones of the light sources is controlled based on the compensated backlight value.

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