Apparatus and method for controlling liquid crystal display brightness, and liquid crystal display device

• US 10,269,308 B2
• Filed: 05/19/2016
• Issued: 04/23/2019
• Est. Priority Date: 09/17/2015
• Status: Active Grant

• Current Assignee: Hisense International Company Limited (Qingdao Huatong State-Owned Capital Operation Company Limited), Hisense USA Corporation (Qingdao Huatong State-Owned Capital Operation Company Limited)
• Original Assignee: Hisense Electric Co., Ltd. (Qingdao Huatong State-Owned Capital Operation Company Limited), Hisense International Company Limited (Qingdao Huatong State-Owned Capital Operation Company Limited), Hisense USA Corporation (Qingdao Huatong State-Owned Capital Operation Company Limited)
• Inventors: Yang, Jia, Zhang, Yuxin, Huang, Shunming, Diao, Yujie
• Primary Examiner(s): Jansen, II, Michael J
• Assistant Examiner(s): Abebe, Sosina
• Application Number:
  US15/158,759
• Publication Number:
  US 20170084232A1
• Time in Patent Office: 1,069 Days
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2320/0686 with two or more screen areas displaying information with different brightness or colours
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The disclosure provides an apparatus and method for controlling liquid crystal display brightness, and a liquid crystal display device, where the method includes: determining grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal; pre-obtaining a zone backlight value corresponding to the zone image data block according to the grayscale values in the zone image data block; multiplying the pre-obtained a zone backlight value with a backlight value gain coefficient to obtain a backlight value to which a gain is applied of a backlight zone, wherein the backlight value gain coefficient is more than 1; and mapping the respective zone backlight values to driver circuits of backlight sources in the corresponding backlight zones.

Claims

1. A method for controlling brightness of a liquid crystal display, the method comprising:

determining grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal, wherein the predetermined rule includes a pre-stored function model in which the liquid crystal display is divided into a number of virtual zones at the same proportion as backlight zones and image data of all pixels displayed in one of the virtual zones are aggregated into the zone image data block;

pre-obtaining a zone backlight value corresponding to the zone image data block according to the determined grayscale values of the pixels in the zone image data block;

multiplying the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a gained backlight value of a backlight zone corresponding to the zone image data block, wherein the backlight value gain coefficient is greater than 1 to enhance a zone peak brightness corresponding to the zone image data block;

when it is determined that an average grayscale value of pixels in a zone image data block cluster is below a first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the zone image data block cluster, wherein multiple zone image data blocks including said zone image data block are divided into multiple zone image data block clusters including said data block cluster, each of the zone image data block clusters comprises a number of adjacent ones of the zone image data blocks, and the revision coefficient is less than 1; and

outputting the gained backlight value to a driver circuit of a backlight source in the backlight zone to control brightness of the backlight source in the backlight zone.

2. The method of claim 1, wherein after multiplying the pre-obtained zone backlight value with the backlight value gain coefficient to obtain the gained backlight value of the backlight zone, the method further comprises:

when it is determined that an average grayscale value of the pixels in the zone image data block is below the first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the zone image data block, wherein the revision coefficient is less than 1.

3. The method of claim 2, wherein the revision coefficient determined according to the dispersity of image brightness distribution of the zone image data block and the dispersity of image brightness distribution of the zone image data block have an inverse correspondence relationship where a smaller revision coefficient corresponds to a larger dispersity of image brightness distribution.

4. The method of claim 1, wherein after multiplying the pre-obtained zone backlight value with the backlight value gain coefficient to obtain the gained backlight value of the backlight zone, the method further comprises:

when it is determined that an average grayscale value of pixels in an image comprising the zone image data block is below the first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the image;

wherein the revision coefficient determined according to the dispersity of image brightness distribution of the image is less than 1, and the revision coefficient determined according to the dispersity of image brightness distribution of the image and the dispersity of image brightness distribution of the image have an inverse correspondence relationship where a smaller revision coefficient corresponds to a larger dispersity of image brightness distribution.

5. The method of claim 4, wherein the backlight value gain coefficient is obtained by:

obtaining an average grayscale value of pixels in the image from grayscale values of pixels in the image; and

determining the backlight value gain coefficient according to a correspondence relationship between the average grayscale value of the pixels in the image and the backlight value gain coefficient.

6. The method of claim 1, wherein

the revision coefficient and the dispersity of image brightness distribution have an inverse correspondence relationship where a smaller revision coefficient corresponds to a larger dispersity of image brightness distribution.

7. The method of claim 6, wherein the backlight value gain coefficient is obtained by:

obtaining the average grayscale value of all pixels in the zone image data block cluster, and

determining the backlight value gain coefficient according to a relationship between the average grayscale value and the backlight value gain coefficient.

8. A liquid crystal display device, comprising:

a memory configured to store programs and various preset lookup table data;

an apparatus for controlling brightness of a liquid crystal display;

the apparatus configured to;

execute the programs stored in the memory, and invoke the various lookup table data according to the executed programs;

receive an image signal, process image data, and output the image data to a timing controller so that the timing controller generates a driver signal according to the image data to control a liquid crystal panel to display an image; and

output zone backlight values to a backlight processing component according to the image signal;

the backlight processing component configured to determine duty ratios of corresponding PWM signals according to the zone backlight values, and to output the duty ratios to a PWM driver component; and

the PWM driver component configured to generate PWM control signals to control backlight sources in backlight zones;

wherein the apparatus for controlling brightness of the liquid crystal display includes a memory and one or more processors, wherein one or more computer readable program codes are stored in the memory, and the one or more processors are configured to execute the one or more computer readable program codes to perform;

determining grayscale values in a zone image data block under a predetermined rule according to a received image signal, wherein the predetermined rule includes a pre-stored function model in which the liquid crystal panel is divided into a number of virtual zones at the same proportion as the backlight zones and the image data of all pixels displayed in one of the virtual zones are aggregated into the zone image data block;

pre-obtaining a zone backlight value corresponding to the zone image data block according to the determined grayscale values of the pixels in the zone image data block;

multiplying the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a gained backlight value of a backlight zone corresponding to the zone image data block, wherein the backlight value gain coefficient is greater than 1 to enhance a zone peak brightness corresponding to the zone image data block;

when it is determined that an average grayscale value of pixels in an image comprising the zone image data block is below a first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the image, wherein the revision coefficient is less than 1;

outputting the gained backlight value to a driver circuit of a backlight source in the backlight zone to control brightness of the backlight source in the backlight zone.

9. The liquid crystal display device of claim 8, wherein the one or more processors are further configured to execute the one or more computer readable program codes to perform:

when it is determined that an average grayscale value of the pixels in the zone image data block is below the first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the zone image data block, wherein the revision coefficient is less than 1.

10. The liquid crystal display device of claim 8, wherein the one or more processors are further configured to execute the one or more computer readable program codes to perform:

when it is determined that an average grayscale value of pixels in a zone image data block cluster is below the first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the zone image data block cluster, wherein multiple zone image data blocks including said zone image data block are divided into multiple zone image data block clusters including said zone image data block cluster, and each of the zone image data block clusters comprises a number of adjacent ones of the zone image data blocks, wherein the revision coefficient determined according to the dispersity of image brightness distribution of the zone image data block cluster is less than 1.

11. The liquid crystal display device of claim 8, wherein the one or more processors are configured to execute the one or more computer readable program codes to perform:

obtaining the backlight value gain coefficient by;

obtaining the average grayscale value of pixels in the image from grayscale values of the image; and

determining the backlight value gain coefficient according to a correspondence relationship between the average grayscale value and the backlight value gain coefficient.

12. The liquid crystal display device of claim 10, wherein the one or more processors are configured to execute the one or more computer readable program codes to perform:

obtaining the backlight value gain coefficient by;

obtaining the average grayscale value of pixels in the zone image data block cluster, and

determining the backlight value gain coefficient according to a relationship between the average grayscale value and the backlight value gain coefficient.

13. A method for controlling brightness of a liquid crystal display, the method comprising:

determining grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal, wherein the predetermined rule includes a pre-stored function model in which the liquid crystal display is divided into a number of virtual zones at the same proportion as backlight zones and image data of all pixels displayed in one of the virtual zones are aggregated into the zone image data block;

pre-obtaining a zone backlight value corresponding to the zone image data block according to the determined grayscale values in the pixels of the zone image data block;

multiplying the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a gained backlight value of a backlight zone corresponding to the zone image data block, wherein the backlight value gain coefficient is greater than 1;

when it is determined that an average grayscale value of pixels in the zone image data block is below a first threshold, multiplying the gained backlight value to with a revision coefficient determined according to a dispersity of image brightness distribution of the zone image data block, wherein the revision coefficient is less than 1; and

outputting the zone backlight value to a driver circuit of a backlight source in the backlight zone to control brightness of the backlight source.

14. The method of claim 13, wherein the revision coefficient and the dispersity of image brightness distribution have an inverse correspondence relationship where a smaller revision coefficient corresponds to a larger dispersity of image brightness distribution.

15. The method of claim 13, wherein after multiplying the pre-obtained zone backlight value with the backlight value gain coefficient to obtain the gained backlight value of the backlight zone, the method further comprises:

when it is determined that an average grayscale value of pixels in an image comprising at least one zone image data block is below a first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the image;

wherein the revision coefficient is less than 1, and the revision coefficient and the dispersity of image brightness distribution have an inverse correspondence relationship where a smaller revision coefficient corresponds to a larger dispersity of image brightness distribution.

16. The method of claim 15, wherein the backlight value gain coefficient is obtained by:

obtaining an average grayscale value of pixels in the image from grayscale values of pixels in the image; and

determining the backlight value gain coefficient according to a correspondence relationship between the average grayscale value and the backlight value gain coefficient.

17. The method of claim 13, wherein after multiplying the pre-obtained zone backlight value with the backlight value gain coefficient to obtain the gained backlight value of the backlight zone, the method further comprises:

when it is determined that an average grayscale value of pixels in a zone image data block cluster is below a first threshold, multiplying the gained backlight value with a revision coefficient determined according to a dispersity of image brightness distribution of the zone image data block cluster, wherein all zone image data blocks are divided into multiple zone image data block clusters, and each of the zone image data block clusters comprises multiple adjacent ones of the zone image data blocks;

wherein the revision coefficient is less than 1, and the revision coefficient and the dispersity of image brightness distribution have an inverse correspondence relationship where a smaller revision coefficient corresponds to a larger dispersity of image brightness distribution.

18. The method of claim 17, wherein the backlight value gain coefficient is obtained by:

obtaining an average grayscale value of all pixels in the zone image data block cluster, and

determining the backlight value gain coefficient according to a relationship between the average grayscale value and the backlight value gain coefficient.