Fail-safe architecture for local dimming display device

Abstract

SOLUTION: A display device 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 luminance levels of the plurality of light sources of the backlight device 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 control others of the plurality of light sources to a predetermined luminance level in the failure mode.EFFECT: The luminance level of pixels located in a zone corresponding to a failed light source is effectively increased.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] A panel display device including a light transmissive display panel (e.g., a light transmissive liquid crystal display (LCD) panel) may include a backlight device for illuminating the light transmissive display panel. Recent backlight devices such as a direct-lit backlight, a full array backlight, etc. may be configured to illuminate a display panel using a two-dimensional (2D) array of light sources (e.g., light emitting diodes (LEDs)). By using a 2D light source array in the backlight device, a local dimming function can be implemented that can achieve high dynamic contrast and low power consumption by individually controlling each light source of the 2D light source array according to input image data.

Summary of the Invention

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

[0004] In an exemplary embodiment, the present disclosure provides a display device including a backlight 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 luminance 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 in the failure mode, to control other light sources of the plurality of light sources to a predetermined luminance level.

[0005] In other exemplary embodiments, the present disclosure provides a display driver including 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 in the failure mode, to control the other light sources of the plurality of light sources to a predetermined brightness level. The driver circuit is configured to drive the display panel based on the first input image data.

[0006] In still other exemplary embodiments, the present disclosure provides a method. The method includes setting a local dimming circuit to a first local dimming mode. The method further includes individually controlling, by the local dimming circuit in the first local dimming mode, the brightness levels of a plurality of light sources of a backlight device based on first input image data. The method further includes setting the local dimming circuit to a failure mode in response to a 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, the brightness of the other light sources of the plurality of light sources to a predetermined brightness level.

[0007] Other features and aspects will be described in more detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0008]

Figure 1

[0009]

Figure 2

[0010] FIG. 2 illustrates an arrangement example of light sources of a backlight device according to one or more embodiments.

Figure 3

[0011]

Figure 4

[0012]

Figure 5

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Figure 6

[0014]

Figure 7A

[0015]

Figure 7B

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Figure 8A

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Figure 8B

[0018]

Figure 9

[0019]

Figure 10

[0020]

Figure 11

[0021]

Figure 12

[0022]

Figure 13

[0023]

Figure 14

[0024] For ease of understanding, wherever possible, the same reference numerals are used to indicate the same elements common to the drawings. It is expected that the elements disclosed in one embodiment can be beneficially used in other embodiments without particular description. Subscripts may be attached to the reference numerals to distinguish the same elements from each other. The drawings referred to in this specification should not be understood as being drawn to scale unless otherwise noted. Also, the drawings are often simplified, and details or components are omitted for clarity of presentation and explanation. The drawings and discussions are helpful for explaining the principles discussed below.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The following detailed description is, in essence, merely exemplary and is not intended to limit the present disclosure, its applications, or its uses. Further, there is no intention to be bound by any explicit or implicit theories presented in the foregoing background, overview, brief description of the drawings, or the following detailed description. In the following detailed description, numerous specific details are presented in order to provide a deeper understanding of the disclosed technology. However, it will be apparent to those skilled in the art that the disclosed technology may be practiced without these specific details. In other instances, well-known configurations have not been described in detail to avoid unnecessarily complicating the description.

[0026] As used herein, the term "coupled" means directly connected or connected through one or more intervening components or circuits. Further, throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as adjectives for elements (i.e., any noun in the application). 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 being only a single element, unless specified otherwise by the use of terms such as "before," "after," "single," and other similar terms. Rather, the use of ordinal numbers is for the purpose of distinguishing elements. For example, a first element is distinct from a second element, and the first element may include more than one element and may follow (or precede) the second element in the ordering of elements.

[0027] A panel display device including a light-transmissive display panel (e.g., a light-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)). By using a 2D light source array in the backlight device, it becomes possible to implement a local dimming function that can achieve high dynamic contrast and low power consumption by individually controlling each light source of the 2D light source array according to input image data.

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

[0029] The present disclosure provides various techniques for avoiding partial loss of the display that may occur due to the failure of one or more light sources of the backlight device. In one or more embodiments, the 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 luminance 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 plurality of light sources, and in the failure mode, control the luminance of the other light sources of the plurality of light sources to a predetermined luminance level. In one implementation, the predetermined luminance level may be the maximum luminance level allowed for the plurality of light sources. Hereinafter, detailed embodiments for avoiding partial loss of the display that may occur due to the failure of one or more light sources of the backlight device will be described.

[0030] FIG. 1 illustrates a configuration example 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 light-transmissive display panel such as a liquid crystal display (LCD) panel. The 2D backlight device 200 is located behind the display panel 100 and illuminates the display panel 100. The 2D backlight device 200 includes an array of light sources 210 configured to illuminate corresponding zones of the display panel 100. In one implementation, each light source 210 includes a light emitting diode (LED) or other type of light source.

[0031] FIG. 2 illustrates an arrangement example of the light sources 210 of the backlight device 200 according to one or more embodiments. In the following, directions may be indicated by the X-axis and the Y-axis. Here, 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 zones 110, and the light sources 210 are arranged such that the projection of each light source 210 onto the display panel 100 is located at the center (e.g., the geometric center) of the corresponding zone 110. Since the light emitted from each light source 210 spreads as it travels, each light source 210 is configured to primarily illuminate the corresponding zone 110 but also secondarily illuminate the adjacent zones 110 surrounding the corresponding zone 110. In one implementation, the zones 110 have a rectangular (e.g., square) shape and are arranged in a matrix. In other implementations, the zones 110 may have other shapes such as rhombus or hexagonal as long as the zones 110 completely cover the display panel 100. Although 288 light sources 210 are illustrated in FIG. 2, those skilled in the art will understand that the 2D backlight device 200 may include more or fewer than 288 light sources 210. In an actual implementation, the 2D backlight device 200 may include hundreds to thousands of light sources 210.

[0032] Returning to FIG. 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, with the leftmost display driver configured to drive the left one-third of the display panel 100, the middle display driver configured to drive the middle one-third, and the rightmost display driver configured to drive the right one-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 gradation of each pixel of the display panel 100. The host 2000 may 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 a non-transitory memory for storing data. The timing controller 500 is configured to provide timing control of the display driver 300 during the image display on the display panel 100. In some implementations, the timing controller 500 may 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, a local dimming circuit 550 is provided that is configured to generate backlight data to implement a local dimming function for individually controlling the luminance levels of the light sources 210 of the 2D backlight device 200 and supply the backlight data to the backlight driver 600. Depending on the implementation, the backlight data may include backlight values for each light source 210, and the backlight driver 600 may be configured to control the light sources 210 based on the backlight values. In one implementation, the backlight value for each light source 210 may indicate a specified luminance level of each light source 210, and the backlight driver 600 may be configured to control the luminance levels of the light sources 210 as specified by the backlight values.

[0035] Depending on the implementation, the local dimming circuit 550 may further be configured to process the input image data to generate processed image data and supply the processed image data to the display driver 300. In such an implementation, the display driver 300 may 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 a failure of one or more light sources 210. The local dimming circuit 550 is configured to enter a failure mode in response to a failure of at least one of the light sources 210. The local dimming circuit 550 is further configured to control the luminance levels of the other light sources 210 to a predetermined luminance level that is high enough such that, in the failure mode, the zone 110 corresponding to the failed light source 210 is illuminated by the light sources 210 adjacent to the failed light source 210. Thereby, the user can visually recognize the portion of the image to be displayed in the zone 110 corresponding to the failed light source 210, thereby avoiding a partial loss of the display on the display panel 100. In one implementation, the predetermined luminance level can be the maximum allowable luminance level for the light source 210 in order to illuminate the zone 110 corresponding to the failed light source 210 as brightly as possible with the adjacent light sources 210. In other implementations, the predetermined luminance level may be different from the maximum allowable luminance level.

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

[0038] FIG. 3 illustrates a configuration example of the 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 the host 2000 (illustrated in FIG. 1) and receive a failure flag from the 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 luminance levels of the respective 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 input image data to generate analysis data. In one implementation, the image analysis circuit 560 may be configured to calculate the average image level (APL) of each zone 110 of the display panel 100 based on the input image data, and the analysis data may include the APL of each zone 110.

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

[0041] The backlight control circuit 580 is configured to generate backlight data that may include backlight values for controlling the luminance levels of the respective 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 where the analysis data includes the APL of each zone of the display panel 100 and the backlight data includes backlight values for the respective light sources 210, the backlight control circuit 580 may be configured to determine the backlight value for each light source 210 based on the APL of the zone 110 corresponding to the respective 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 210) to a sufficiently high predetermined luminance level. Thereby, the light sources 210 surrounding the failed light source 210 can illuminate the zone 110 corresponding to the failed light source 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 to a value corresponding to the allowable maximum luminance level in order to cause the non-failed light sources 210 to emit light at the allowable maximum luminance level.

[0043] The image processing circuit 590 is configured to process input image data based on analysis data to generate processed image data. The processed image data is supplied to a display driver 300 configured to drive the display panel 100 based on the processed image data. The image processing executed by the image processing circuit 590 includes gamma conversion. In one implementation, the gamma conversion may convert the input gradation of each pixel to the gamma-converted gradation according to a gamma curve determined for each pixel based on the APL described in the analysis data. Here, the gamma curve is a curve representing the correspondence between the input gradation and the gamma-converted gradation in the gamma conversion. The input gradation of each pixel may be generated by performing desired processing (e.g., color adjustment, demura correction, deband correction, image enlargement / reduction, or other processing) on the gradation of each pixel described in the input image data. In other implementations, the gradation described in the input image data may be used as the input gradation as it is. The gamma-converted gradation of each pixel is used to determine the gradation of each pixel described in the post-treatment image data. In one implementation, the gamma-converted gradation determined by the gamma conversion may be used as the gradation described in the processed image data as it is. In one or more embodiments, the gamma value of the gamma curve used for the gamma conversion may be determined based on the APL of each zone 110 for each pixel of each 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 target gamma curve. The processing executed by the image processing circuit 590 may further include various image processing other than gamma conversion, such as color adjustment, demura correction, deband correction, image enlargement / reduction, and other image processing.

[0044] In one or more embodiments, the image processing circuit 590 may be further configured to determine a post-compensation gamma curve for increasing the luminance level of the pixels located in the zone 110 corresponding to the failed light source 210 in response to the local dimming circuit 550 entering the failure mode, for the pixels located in the zone 110 corresponding to the failed light source 210. In such an embodiment, the image processing circuit 590 may be configured to perform gamma conversion on the input gradation of the pixels located in the zone 110 corresponding to the failed light source 210 according to the post-compensation gamma curve.

[0045] FIG. 4 illustrates an example of a post-compensation gamma curve determined for the pixels located in the zone 110 corresponding to the failed light source 210 according to one or more embodiments. The solid line indicates the post-compensation gamma curve, while the dashed line indicates the original gamma curve determined based on the APL of the zone 110 corresponding to the failed light source 210, similar to in the local dimming mode. The post-compensation gamma curve is determined such that the gamma value of the post-compensation gamma curve is smaller than the gamma value of the original gamma curve. In one implementation, the post-compensation gamma curve is determined such that the gamma value of the post-compensation gamma curve is equal to or a predetermined value close to 1.0. Note that while the default gamma value of widely used display devices is 2.0, a gamma value of 1.0 represents a linear correspondence between the input gradation and the post-gamma-conversion gradation. The gamma value of the post-compensation gamma curve may be determined to be considerably smaller than 2.2. By using the post-compensation gamma curve determined in this way, the luminance level of the pixels located in the zone 110 corresponding to the failed light source 210 effectively increases.

[0046] FIG. 5 is a flowchart illustrating an example of a method 400 for implementing a fail-safe function to avoid partial loss of display when a failure occurs in one or more of the light sources 210 according to one or more embodiments. It will be recognized that any of the following steps may be performed in any suitable order and that the method 400 may be implemented in any suitable environment.

[0047] Depending on the implementation, the host 2000 (shown in FIG. 1) may have information about the failure of the light source 210 of the backlight device 200 before the activation of the display device 1000. When the display device 1000 is activated, if the host 2000 recognizes 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. When the local dimming circuit 550 receives a backlight failure command from the host 2000 (i.e., when one or more light sources 210 have failed) during activation in step 402, 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. Further, the backlight control circuit 580 of the local dimming circuit 550 adjusts the luminance level of the non-failed light sources 210 to a predetermined luminance level, for example, 100% or the allowable maximum luminance level, according to the backlight data. In one implementation, the backlight control circuit 580 may determine the backlight value of the non-failed light sources 210 included in the backlight data to a value corresponding to the allowable maximum luminance level to cause the non-failed light sources 210 to emit light at the allowable maximum luminance level. The process then proceeds to step 422.

[0049] In step 422, the image processing circuit 590 of the local dimming circuit 550 adjusts the gamma curve used for gamma conversion for the pixels located in the zone 110 corresponding to the failed light source 210. In one implementation, the image processing circuit 590 determines a post-compensation gamma curve for the pixels located in the zone 110 corresponding to the failed light source 210, and performs gamma conversion for the pixels located in the zone 110 corresponding to the failed light source 210 according to the post-compensation gamma curve. As described in connection with FIG. 4, in order to increase the luminance value of the pixels located in the zone 110 corresponding to the failed light source 210, the post-compensation gamma curve may be determined such that the gamma value of the post-compensation gamma curve is equal to, or close to, 1.0.

[0050] If the local dimming circuit 550 does not receive a backlight failure command at 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 executes the local dimming function and individually controls the brightness levels of the light sources 210 of the backlight device 200 based on the analysis data received from the image analysis circuit 560. Thereafter, the process proceeds to step 406.

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

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

[0053] In step 430, the local dimming circuit 550 enters the failure mode, thereby disabling the local dimming function. In addition, the backlight control circuit 580 of the local dimming circuit 550 adjusts the brightness levels of the non-failed light sources 210 to a predetermined brightness level (e.g., 100% or the allowable maximum brightness level) by the backlight data, similar to step 420. Thereafter, the process proceeds to step 432.

[0054] In step 432, the image processing circuit 590 of the local dimming circuit 550 adjusts the gamma curve used for gamma conversion for the pixels located in zone 110 corresponding to the failed light source 210, similar to step 422. In one implementation, the image processing circuit 590 determines a post-compensation gamma curve for the pixels located in zone 110 corresponding to the failed light source 210, and performs gamma conversion for the pixels located in zone 110 corresponding to the failed light source 210 according to the post-compensation gamma curve. As discussed in relation to step 422, the post-compensation gamma curve may be determined such that the gamma value of the post-compensation gamma curve is equal to or close to a predetermined value of 1.0 in order to increase the luminance level of the pixels located in zone 110 corresponding to the failed light source 210.

[0055] In step 434, the local dimming circuit 550 transmits a backlight failure command to the host 2000, thereby notifying the host 2000 of the occurrence of a failure of one or more light sources 210. Thereby, the host 2000 recognizes the failure of one or more light sources 210. At the next startup of the display device 1000, the host 2000 may transmit a backlight failure command to the local dimming circuit 550 to notify the local dimming circuit 550 of the failure of one or more light sources 210.

[0056] FIG. 6 illustrates a configuration example of a display device 3000 according to another embodiment. 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 is configured similarly to the local dimming circuit 550 illustrated in FIGS. 1 and 3 and may operate similarly to the local dimming circuit 550. The local dimming circuit 1350 may be configured to generate backlight data and supply it to the backlight driver 600. The local dimming circuit 1350 may further be configured to supply the processed image data to the driver circuit 1360. The driver circuit 1360 may be configured to drive the display panel 100 based on the processed image data.

[0057] The method 400 illustrated in FIG. 5 disables the local dimming circuit in response to the failure of one or more light sources. However, the present disclosure recognizes that even if a small number of light sources 210 (e.g., one light source 210) fail, particularly in embodiments where the light sources 210 are spaced apart at relatively small intervals, it can be compensated by increasing the brightness levels of the light sources adjacent to the failed light source. In embodiments where the failure of a small number of light sources 210 is compensated by increasing the brightness levels of the adjacent light sources 210, the local dimming function may be implemented regardless of the occurrence of such light source failures.

[0058] FIG. 7A illustrates an example of compensation for light source failure according to one or more embodiments. In the illustrated example, a failure has occurred in one light source 210 indicated by diagonal cross-hatching. In this case, in one or more embodiments, the failure of this light source 210 may be compensated by increasing the brightness levels of eight light sources 210 adjacent to the failed light source 210. The light sources used for compensation are indicated by vertical and horizontal hatching in FIG. 7A.

[0059] FIG. 7B illustrates an example of compensation for light source failure according to one or more embodiments. In the illustrated example, failures have occurred in four light sources indicated by diagonal cross-hatching. Again, in this case, the failure of the four light sources may be compensated by increasing the brightness levels of 19 light sources adjacent to the four failed light sources. The light sources used for compensation are indicated by vertical and horizontal hatching in FIG. 7B.

[0060] In one implementation, the luminance levels of the light sources 210 adjacent to at least one failed light source 210 may be controlled as follows. First, a base backlight value for each light source 210 may be determined based on the input image data. In one implementation, the base backlight value for each light source 210 may be determined based on the APL of the zone corresponding to that light source 210. Note that the APL of each zone may be calculated based on the input image data. Subsequently, a compensated backlight value for the light sources 210 adjacent to the at least one failed light source 210 is determined based on the base backlight value for the light sources 210 adjacent to the failed light source 210 and the fault location data. The fault location data indicates the location or arrangement of the at least one failed light source 210. The compensated backlight value of the light sources 210 adjacent to the at least one failed light source 210 may be determined by modifying the base backlight value of the adjacent light sources 210 based on the fault location data. In one implementation, a compensation factor, which may indicate the amount by which the luminance level of the adjacent light sources 210 should be increased, is determined based on the fault location data, and the compensated backlight value of the adjacent light sources 210 may be determined by applying the compensation factor to each base backlight value of the adjacent light sources 210. The compensated backlight value of the light sources 210 adjacent to the failed light source 210 may indicate a specified luminance level of the adjacent light sources 210. The light sources 210 adjacent to the failed light source 210 may be controlled based on the compensated backlight values determined for those adjacent light sources 210.

[0061] FIG. 8A illustrates a configuration example of a local dimming circuit 1550 configured to compensate for a failure of one or more light sources 210 by increasing the luminance level of the light sources 210 adjacent to the failed light source 210 according to one or more embodiments. The local dimming circuit 1550 may be an embodiment of the local dimming circuit 550 illustrated in FIG. 1 or an embodiment of the local dimming circuit 1350 illustrated in FIG. 6. In the embodiment illustrated in FIG. 8A, the local dimming circuit 1550 is configured to receive input image data from a host 2000 (illustrated in FIG. 1) and a failure flag from a backlight driver 600. The local dimming circuit 1550 is configured to process the input image data to generate processed image data and generate backlight data to control the luminance level of each light source 210 of the backlight device 200. In one or more embodiments, the local dimming circuit 1550 includes an image analysis circuit 1560, a mode control circuit 1570, a backlight control circuit 1580, an image processing circuit 1590, and a compensation coefficient determination circuit 1600.

[0062] The image analysis circuit 1560 is configured to analyze input image data to generate analysis data in the same manner as the image analysis circuit 560 described in connection with FIG. 3. In one implementation, the image analysis circuit 1560 may be configured to calculate the APL of each zone 110 of the display panel 100 based on the input image data, and the analysis data may include the APL of each zone 110.

[0063] The mode control circuit 1570 is configured to control the operation mode of the local dimming circuit 1550 according to the fault flag and the fault position data received from the backlight driver 600 (illustrated in FIG. 1). As described above, the fault position data may indicate the position or arrangement of the failed light source 210. In one or more embodiments, the mode control circuit 1570 may be configured to identify the number of failed light sources 210 based on the fault flag and the fault position data. The mode control circuit 1570 may further be configured to set the local dimming circuit 1550 to the local dimming mode in which the local dimming function is implemented when there is no failed light source 210. The mode control circuit 1570 may further be configured to set the local dimming circuit 1550 to the fault 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 set the local dimming circuit 1550 to the "second" local dimming mode when the number of failed light sources 210 is not zero but less than the predetermined threshold. The "second" local dimming mode is an operation mode that is activated while compensating for the failure of the light source 210 by increasing the luminance level of the light source 210 adjacent to the failed light source 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 by 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 the same manner as the image processing circuit 590 described in relation to FIG. 3, and generate processed image data. The processed image data may be supplied to a display driver 300 (illustrated in FIG. 1) configured to drive the display panel 100 based on the processed image data. The image processing executed by the image processing circuit 1590 may include gamma conversion. In one implementation, the gamma conversion may convert the input gradation of each pixel to the post-gamma conversion gradation according to a gamma curve determined for each pixel based on the APL described in the analysis data. The input gradation of each pixel may be generated by performing a desired process on the gradation described in the input image data. The post-gamma conversion gradation of each pixel is used to determine the gradation of each pixel described in the processed image data. The post-gamma conversion gradation determined by the gamma conversion may be used as it is as the gradation described in the processed image data. Details of the determination of the gamma curve will be described in detail later. The processing executed by the image processing circuit 1590 may further include various image processes other than gamma conversion, such as color adjustment, demura correction, de-banding correction, image enlargement / reduction, or other image processes.

[0065] In one or more embodiments, the image processing circuit 1590 may be further configured to determine a compensated gamma curve to increase the luminance level of the pixels located in the zone 110 corresponding to the failed light source 210 for the pixels located in the zone 110 corresponding to the failed light source 210 as described in relation to FIG. 4 in response to the local dimming circuit 1550 entering the failure mode. In such an embodiment, the image processing circuit 1590 may be configured to perform gamma conversion on the input gradation of the pixels located in the zone 110 corresponding to the failed light source 210 according to the compensated gamma curve.

[0066] The compensation factor determination circuit 1600 is configured to generate compensation factor data based on the fault location data received from the backlight driver 600 (illustrated in FIG. 1). As described in connection with FIG. 1, the fault location data may indicate the arrangement or position of the failed light source 210. The compensation factor data includes a compensation factor indicating the amount by which the luminance level of the light sources 210 adjacent to the failed light source 210 should be increased. In one implementation, the compensation factor for the light sources 210 adjacent to the failed light source 210 may be determined to be a non-zero value. The compensation factor for the light sources 210 not adjacent to any of the failed light sources 210 may be determined to be 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 factor data received from the compensation factor determination circuit 1600. FIG. 8B illustrates a configuration example of the backlight control circuit 1580 according to one or more embodiments. In the illustrated embodiment, the backlight control circuit 1580 includes a compensation factor look-up table (LUT) 1582, a basic backlight data calculation circuit 1584, and a backlight data compensation circuit 1586.

[0068] The compensation factor LUT 1582 is configured to store the compensation factor data received from the compensation factor determination circuit 1600. As described above, the compensation factor data includes the compensation factors determined for each light source 210. The compensation factor LUT 1582 is configured to supply the stored compensation factor data to the backlight data compensation circuit 1586. For example, the compensation factor LUT 1582 may be configured to be addressable by the coordinates of each light source 210, where the compensation factor determined for each light source 210 is indicated by "(X,Y)" in FIG. 8B.

[0069] The basic backlight data calculation circuit 1584 is configured to generate basic backlight data based on the analysis data received from the image analysis circuit 1560 (illustrated in FIG. 8A). The basic backlight data includes the basic backlight values determined for each light source 210. In an embodiment where the analysis data includes the APL of each zone 110, the basic backlight data calculation circuit 1584 may be configured to calculate the basic backlight values for each light source 210 based on the APL of the zone 110 corresponding to each light source 210. The basic backlight data calculation circuit 1584 is further configured to supply the basic backlight data thus generated 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 calculation circuit 1584 based on the compensation coefficients received from the compensation coefficient LUT 1582. The backlight data may include the compensated backlight values for each light source 210. Since the compensation coefficients of the light sources 210 not adjacent to the failed light source 210 are zero, the compensated backlight values of the light sources 210 not adjacent to the failed light source 210 are the same as the basic backlight values of those light sources 210. On the other hand, the compensated backlight values of the 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 coefficients determined for those light sources 210. In one implementation, the backlight data, which may include the compensated backlight values, is supplied to the backlight driver 600 to control the luminance levels of each light source 210. The compensated backlight values for each light source 210 may indicate the designated luminance levels of each light source 210, and the luminance levels of each light source 210 may be controlled based on the compensated backlight values for each light source 210.

[0071] FIG. 9 illustrates an example of a method 900 that implements a fail - safe function to avoid partial loss of display when a failure occurs in one or more light sources 210 according to one or more embodiments, while compensating for the failure of one or more light sources 210 by increasing the luminance levels of the light sources 210 adjacent to the failed light source 210. It should be recognized that, unless otherwise apparent, the following steps may be performed in any suitable order and that method 900 may be implemented in any suitable environment.

[0072] As described in connection with FIG. 5, the host 2000 (illustrated in FIG. 1) may have information regarding the failure of the light sources 210 of the backlight device 200 before the display device 1000 is powered on. When the display device 1000 is powered on, if the host 2000 recognizes that one or more light sources 210 are failed, the host 2000 may send a backlight failure command to the local dimming circuit 550 of the timing controller 500.

[0073] If the local dimming circuit 1550 does not receive a backlight failure command at startup in step 902, the local dimming circuit 1550 enters the 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 compensation for light source failures is not performed. The backlight control circuit 1580 implements the local dimming function in the first local dimming mode and individually controls the luminance levels of each light source 210 of the backlight device 200 based on the analysis data received from the image analysis circuit 1560. Thereafter, the process proceeds to step 906.

[0074] In step 906, the local dimming circuit 1550 checks the state of the backlight device 200 based on whether it receives a fault flag from the backlight driver 600. The local dimming circuit 1550 remains in the first local dimming mode in step 910 as long as the local dimming circuit 1550 does not receive a fault flag. The local dimming circuit 1550 may check the state of the backlight device 200 every predetermined number of frames as long as the local dimming circuit 1550 remains in the first local dimming mode.

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

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

[0077] In step 932, the image processing circuit 1590 of the local dimming circuit 1550 adjusts the gamma curve used for gamma conversion for the pixels located in zone 110 corresponding to the failed light source 210, in the same manner as steps 422 and 432 described in relation to FIG. 5. In one implementation, the image processing circuit 1590 determines a post-compensation gamma curve for the pixels located in zone 110 corresponding to the failed light source 210, and performs gamma conversion for the pixels located in zone 110 corresponding to the failed light source 210 according to the post-compensation gamma curve. As discussed in relation to step 422 illustrated in FIG. 5, in order to increase the luminance level of the pixels located in zone 110 corresponding to the failed light source 210, the post-compensation gamma curve may be determined such that the gamma value of the post-compensation gamma curve becomes a predetermined value equal to or close to 1.0. Thereafter, the process proceeds to step 934.

[0078] In step 934, the local dimming circuit 1550 transmits a backlight failure command to the host 2000, thereby notifying the host 2000 of the occurrence of a failure of one or more light sources 210. Thereby, the host 2000 recognizes the failure of one or more light sources 210. At the next startup of the display device 1000, the host 2000 may transmit a backlight failure command to the local dimming circuit 1550 to notify the local dimming circuit 1550 of the failure of one or more light sources 210.

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

[0080] In step 920, the local dimming circuit 1550 disables the local dimming function. Further, the backlight control circuit 1580 of the local dimming circuit 1550 adjusts the brightness levels of the non-faulty light sources 210 to a predetermined brightness level, for example, 100% or the allowable maximum brightness level, according to the backlight data. In one implementation, the backlight control circuit 1580 may determine the backlight values of the non-faulty light sources 210 included in the backlight data to values corresponding to the allowable maximum brightness level, and cause the non-faulty light sources 210 to emit light at the allowable maximum brightness level. The process then proceeds to step 922.

[0081] In step 922, the local dimming circuit 1550 reads the fault location data from the backlight driver 600. Note that the fault location data may indicate the arrangement or position of the faulty light source 210. Then, the process proceeds to step 924.

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

[0083] In step 926, the compensation coefficient determination circuit 1600 determines a compensation coefficient for each light source 210 based on the fault location data. The fault location data may indicate the arrangement or position of the faulty light source 210. In one implementation, the compensation coefficients for the light sources 210 adjacent to at least one faulty light source 210 may be determined to non-zero values. The compensation coefficients for the light sources 210 not adjacent to the faulty light source 210 may be determined to zero. The determined compensation coefficients are supplied to the backlight control circuit 1580 and stored in the compensation coefficient LUT 1582 of the backlight control circuit 1580. Then, the process 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 operation mode that implements the local dimming function together with compensation for light source failures. In the second local dimming mode, the backlight data compensation circuit 1586 of the backlight control circuit 1580 generates a compensated backlight value for each light source 210 by correcting the base backlight value for each light source 210 based on the compensation coefficient for each light source 210. The compensated backlight value for each light source 210 is supplied to the backlight driver 600, and the backlight driver 600 controls the luminance level of each light source 210 based on the compensated backlight value for each light source 210.

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

[0086] As described above, the gamma conversion performed by the image processing circuit 1590 (illustrated in FIG. 8A) may be based on a gamma curve determined for each pixel based on the APL described in the analysis data generated by the image analysis circuit 1560. FIG. 10 illustrates an example of the APL of each zone 110 of the display panel 100 according to one or more embodiments. In FIG. 10, APL (i, j) indicates the APL of the zone 110 in the (i + 1)-th row from the top and the (j + 1)-th column from the left. Here, i is a natural number greater than or equal to 0 and less than or equal to M - 1, and j is a natural number greater than or equal to 0 and less than or equal to N - 1. Hereinafter, an example of a method for determining the gamma value of the gamma curve used for gamma conversion for each pixel according to one or more embodiments will be described.

[0087] Referring to FIG. 11, the black circles, hatched circles, and white circles indicate the corners of each zone 110, which are hereinafter referred to as "zone corners". In the embodiment of FIG. 11, the zone 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 a "zone corner APL" for each zone corner from the APL of each zone 110. The "zone corner APL" of a certain zone corner represents the APL of the area around that zone corner. In the embodiment illustrated in FIG. 11, APL_CORNER (i, j) indicates the zone corner APL of the zone corner in the (i + 1)-th row from the top and the (j + 1)-th column from the left. Here, i is a natural number from 0 to M, and j is a natural number from 0 to N.

[0088] Note that the zone corners not located at the four corners of the display panel 100 are shared by a plurality of zones 110, more specifically, two or four zones 110. In one implementation, the zone corner APL of a target zone corner not located at the four corners of the display panel 100 is determined as the average of the APLs of each zone 110 sharing the target zone corner. On the other hand, the zone corner APL of the zone corner located at each corner of the display panel 100 is determined to be equal to the APL of the zone 110 at that corner of the display panel 100.

[0089] More specifically, in one or more embodiments, the "zone corners" may be classified into the following three types: (1) the zone corners located at the corners of the display panel 100 indicated by white circles, (2) the zone corners located on the sides of the display panel 100 indicated by hatched circles, and (3) the other zone corners indicated by black circles. The determination of the zone corner APL of each zone corner may depend on the type of each zone corner as follows.

[0090] (1) Zone corners located at the corners of the display panel The zone corner APL of the zone corners located at the four corners of the display panel 100 may be determined according to the following formulas (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) (1c) APL_CORNER (M+1, N+1) = APL (M, N) (1d)

[0091] (2) Zone corners located on the sides of the display panel The zone corner APL of the zone corners located on the four sides of the display panel 100 may be determined according to the following formulas (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 (2c) APL_CORNER (p, N+1) = {APL (p-1, N) + APL (p, N)} / 2 (2d) Here, p is a natural number from 1 to M, and q is a natural number from 1 to N.

[0092] (3) Other zone corners The zone corner APL of the other zone corners located inside the display panel 100 may be determined according to the following formula (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 each pixel from the zone corner APL of each zone corner. The pixel APL of a certain pixel represents the APL of the area around the pixel. In one implementation, the pixel APL of a certain pixel located in a certain zone 110 is calculated by interpolating the zone corner APL determined for the corner of that zone 110 depending on the position of the pixel in that zone 110.

[0094] FIG. 12 illustrates an example of calculating the pixel APL for a pixel 120 located in zone 110 at the (i + 1)-th row and (j + 1)-th column according to one or more embodiments. Here, i is a natural number from 0 to M, j is a natural number from 0 to N, and (x, y) are the X coordinate and Y coordinate of pixel 120. In the illustrated embodiment, the zone corner APLs determined for the corners of this zone 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 the pixel 120 located at (x, y) may be calculated according to the following formula (4).

Equation

Equation

[0095] Referring to FIG. 13, in one or more embodiments, the gamma value of the gamma curve used for gamma conversion for each pixel may be determined based on the pixel APL calculated for that pixel. In one implementation, the gamma value of the gamma curve used for gamma conversion for each pixel increases as the pixel APL of that pixel increases. In other words, the smaller the pixel APL of the target pixel, the smaller the gamma value of the gamma curve used for gamma conversion for that pixel. FIG. 13 shows that the gamma value of the gamma curve used for gamma conversion increases linearly with the pixel APL, but the gamma value of the gamma curve used for gamma conversion may increase non-linearly with the pixel APL. The image processing circuit 1590 may be configured to perform gamma conversion on the input gradation of each pixel according to a gamma curve defined by a gamma value determined based on the pixel APL of that 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 zone 110 corresponding to the failed light source 210 in the second local dimming mode to increase the luminance of the pixels located in the zone 110. Referring to FIG. 14, the adjustment of the gamma curve for the pixels located in the zone 110 corresponding to a certain failed light source 210 may be achieved by defining a predetermined virtual APL for the zone 110 corresponding to the failed light source 210 and calculating the zone corner APL and the pixel APL using the virtual APL instead of the APL of that zone calculated from the input image data. As a result, the gamma value of the gamma curve used for gamma conversion for the pixels located in the zone 110 corresponding to the failed light source 210 is determined based on the virtual APL. In such an embodiment, the smaller the virtual APL, the smaller the gamma value of the gamma curve used for gamma conversion for the pixels located in the zone 110 corresponding to the failed light source 210. Therefore, the luminance level of the pixels located in the zone 110 corresponding to the failed light source 210 can be increased by setting the virtual APL to a small value, for example, 0. In one implementation, the virtual APL may be 0. In the embodiment illustrated in FIG. 14, assuming that the light source corresponding to the zone 110 in the second row and the third column has failed, the APL (1, 2) of that zone 110 is set to 0.0 regardless of the input image data. By doing so, the luminance level of the pixels located in that zone 110 will increase and compensate for the failure of the light source 210 corresponding to that zone 110.

[0097] In another embodiment, the adjustment of the gamma curve for the pixels located in zone 110 corresponding to the failed light source 210 may be achieved by modifying the APL of zone 110 corresponding to the failed light source 210 and calculating the zone corner APL and the pixel APL using the modified APL instead of the APL of that zone 110 calculated from the input image data. By doing so, the gamma value of the gamma curve used for gamma conversion for the pixels located in zone 110 corresponding to the failed light source 210 will be determined based on the modified APL. In such an embodiment, the smaller the modified APL, the smaller the gamma value of the gamma curve used for gamma conversion for the pixels located in zone 110 corresponding to the failed light source 210. Therefore, the luminance level of the pixels located in zone 110 corresponding to the failed light source 210 can be increased by determining the modified APL to be smaller than the APL of zone 110 corresponding to the failed light source 210 calculated based on the input image data. In one implementation, the modified APL may be calculated by subtracting a certain positive value from the APL of zone 110 corresponding to the failed light source 210.

[0098] The use of "a", "an", "the", "at least one" and similar reference terms in the context of describing the present invention (especially in the context of the following claims) should be construed to cover both singular and plural forms, unless otherwise indicated herein or clearly contradicted by the context. The use of the term "at least one" following a list of one or more items (e.g., "at least one of A and B") should be construed to mean one item selected from the listed items (A or B), or any combination of two or more of the listed items (A and B), unless otherwise described herein or clearly contradicted by the context. The terms "comprising", "having", "including" and "containing" are to be construed as open-ended terms (i.e., meaning "including but not limited to") unless specifically stated otherwise. The recitation of a range of values herein is intended to serve merely as a shorthand reference for individually referring to each separate value falling within the range, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by the context. The use of any examples, or exemplary language (e.g., "such as") provided herein is merely intended to make the understanding of the present invention easier and is not intended to limit the scope of the present invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0099] Exemplary embodiments are described herein. Variations of those exemplary embodiments will be apparent to those skilled in the art upon reading the foregoing description. The inventors expect those skilled in the art to adopt 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. Further, any combination of the above-described elements in all possible variations thereof is included in the invention unless otherwise specifically indicated herein or otherwise clearly contradicted by context.

Claims

1. a backlight device comprising a plurality of light sources configured to illuminate a display panel; In a first local dimming mode, the luminance levels of the plurality of light sources are individually controlled based on first input image data; entering a failure mode in response to a failure of at least one of the plurality of light sources; a local dimming circuit configured to control, in the failure mode, the brightness levels of other light sources of the plurality of light sources to a predetermined brightness level; Equipped Display device.

2. The predetermined luminance level is a maximum allowable luminance level for the plurality of light sources. The display device according to claim 1 .

3. The local dimming circuit further comprises: 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 so as to increase a luminance level of the pixels in the zone; configured to perform gamma conversion on second input image data in the failure mode to generate second output image data used to drive the display panel; A gamma conversion for pixel data of pixels in the zone corresponding to the failed light source of the plurality of light sources is based on a compensated gamma curve. The display device according to claim 1 .

4. The local dimming circuit further comprises: 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 base backlight value for each of the light sources based on the second input image data; the base backlight value for each of the light sources includes a first base backlight value for a failed light source of the plurality of light sources and a second base backlight value for a light source adjacent to the failed light source of the plurality of light sources; determining compensated backlight values ​​for the adjacent light sources of the plurality of light sources based on the second base backlight value and a location of the failed light source of the plurality of light sources; configured to control luminance levels of the adjacent light sources of the plurality of light sources based on the compensated backlight value. The display device according to claim 1 .

5. determining the compensated backlight value includes modifying the second basis backlight value based on the first basis backlight value to increase a luminance level of the adjacent light source of the plurality of light sources. The display device according to claim 4.

6. The local dimming circuit further comprises: 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 threshold; In the second local dimming mode, calculating a first average picture level (APL) for a first zone corresponding to a non-faulty light source of the plurality of light sources based on the 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 gradation of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma converted gradation used to drive the first pixel; defining a predetermined virtual APL for a second zone corresponding to a failed light source of the plurality of light sources; determining a second gamma curve for a second pixel in the second zone based on the predetermined hypothetical APL; and determining a second gamma-converted gray level to be used for driving the second pixel by performing gamma conversion on the second gray level of the second pixel described in the second input image data based on the second gamma curve. The display device according to claim 1 .

7. the smaller the first APL is, the smaller the first gamma value of the first gamma curve is; The predetermined virtual APL is zero. The display device according to claim 6.

8. The local dimming circuit further comprises: enter 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 for a first zone corresponding to a non-faulty light source among the plurality of light sources based on the 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 gradation of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma converted gradation used to drive the first pixel; calculating a second APL for a second zone corresponding to a failed light source among the plurality of light sources based on the second input image data; determining a modified APL for the second zone by modifying the second APL such that the modified APL is less than the second APL; determining a second gamma curve for a second pixel in the second zone based on the modified APL; and determining a second gamma-converted gray level to be used for driving the second pixel by performing gamma conversion on the second gray level of the second pixel described in the second input image data based on the second gamma curve. The display device according to claim 1 .

9. 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; The smaller the corrected APL is, the smaller the second gamma value of the second gamma curve is. The display device according to claim 8.

10. individually controlling, in a first local dimming mode, luminance levels of a plurality of light sources of a backlight device configured to illuminate the display panel based on first input image data; entering a failure mode in response to a failure of at least one of the plurality of light sources; a local dimming circuit configured to control the luminance levels of other light sources of the plurality of light sources to a predetermined luminance level in the failure mode; a driver circuit configured to drive the display panel based on the first input image data; Equipped Display driver.

11. The predetermined luminance level is a maximum allowable luminance level for the plurality of light sources. A display driver as claimed in claim 10.

12. The local dimming circuit further comprises: 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 so as to increase a luminance level of the pixels in the zone; configured to perform gamma conversion on second input image data in the failure mode to generate second output image data used to drive the display panel; A gamma conversion for pixel data of pixels in the zone corresponding to the failed light source of the plurality of light sources is based on a compensated gamma curve. A display driver as claimed in claim 10.

13. The local dimming circuit further comprises: 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 threshold; In the second local dimming mode, determining a base backlight value for each of the light sources based on the second input image data; The base backlight value for each of the light sources is a first base backlight value for a failed light source of the plurality of light sources; a second base backlight value for a light source adjacent to the failed light source in the plurality of light sources; and Equipped with determining compensated backlight values ​​for the adjacent light sources of the plurality of light sources based on the second base backlight value and a location of the failed light source of the plurality of light sources; configured to control luminance levels of the adjacent light sources of the plurality of light sources based on the compensated backlight value. A display driver as claimed in claim 10.

14. determining the compensated backlight value includes modifying the second basis backlight value based on the first basis backlight value to increase a luminance level of the adjacent light source of the plurality of light sources. A display driver as claimed in claim 13.

15. The local dimming circuit further comprises: 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 threshold; In the second local dimming mode, calculating a first average picture level (APL) for a first zone corresponding to a non-faulty light source of the plurality of light sources based on the 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 gradation of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma converted gradation used to drive the first pixel; defining a predetermined virtual APL for a second zone corresponding to a failed light source of the plurality of light sources; determining a second gamma curve for a second pixel in the second zone based on the predetermined hypothetical APL; and determining a second gamma-converted gray level to be used for driving the second pixel by performing gamma conversion on the second gray level of the second pixel described in the second input image data based on the second gamma curve. A display driver as claimed in claim 10.

16. the smaller the first APL is, the smaller the first gamma value of the first gamma curve is; The predetermined virtual APL is zero.

16. A display driver as claimed in claim 15.

17. The local dimming circuit further comprises: enter 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 for a first zone corresponding to a non-faulty light source among the plurality of light sources based on the 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 gradation of the first pixel described in the second input image data based on the first gamma curve to determine a first gamma converted gradation used to drive the first pixel; calculating a second APL for a second zone corresponding to a failed light source among the plurality of light sources based on the second input image data; determining a modified APL for the second zone by modifying the second APL such that the modified APL is less than the second APL; determining a second gamma curve for a second pixel in the second zone based on the modified APL; and determining a second gamma-converted gray level used to drive the second pixel by performing gamma conversion on the second gray level of the second input image data based on the second gamma curve. A display driver as claimed in claim 10.

18. setting the local dimming circuitry in a first local dimming mode; individually controlling, with the local dimming circuit in the first local dimming mode, luminance levels of a plurality of light sources of a backlight device configured to illuminate a display panel based on first input image data; placing the local dimming circuit in a failure mode in response to a failure of at least one of the plurality of light sources; controlling the luminance of another light source of the plurality of light sources to a predetermined luminance level by the local dimming circuit in the failure mode; Includes method.

19. Furthermore, 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, so as to increase a luminance level of the pixels in the zone; performing gamma conversion on second input image data by the local dimming circuit in the failure mode to generate second output image data used to drive the display panel; Including, A gamma conversion for pixel data of pixels in the zone corresponding to the failed light source of the plurality of light sources is based on a compensated gamma curve.

20. The method of claim 18.

20. Furthermore, setting the local dimming circuit to 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 threshold; determining a base backlight value for each of the light sources based on second input image data, the base backlight value for each of the light sources including a first base backlight value for a failed light source of the plurality of light sources and a second base backlight value for a light source adjacent to the failed light source of the plurality of light sources; determining compensated backlight values ​​for the neighboring light sources of the plurality of light sources based on the second base backlight value and a location of the failed light source of the plurality of light sources; controlling luminance levels of the adjacent light sources of the plurality of light sources based on the compensated backlight value; Includes 20. The method of claim 18.

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