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

• US 10,074,318 B2
• Filed: 06/03/2016
• Issued: 09/11/2018
• Est. Priority Date: 09/01/2015
• Status: Active Grant

• Current Assignee: Hisense International Company Limited (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.), Hisense USA Corporation (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.)
• Original Assignee: Hisense Electric Co., Ltd. (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.), Hisense International Company Limited (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.), Hisense USA Corporation (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.)
• Inventors: Zhang, Yuxin, Huang, Shunming, Song, Zhicheng
• Primary Examiner(s): Pardo, Thuy
• Application Number:
  US15/173,205
• Publication Number:
  US 20170061897A1
• Time in Patent Office: 830 Days
• Field of Search: 345102, 345207, 345690, 345698
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

An apparatus for controlling liquid crystal display brightness includes: a zone image grayscale determining section configured to determine grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal; a zone backlight value pre-obtaining section configured to pre-obtain a zone backlight value corresponding to the zone image data block according to the grayscale values; a zone backlight value gain section configured, when it is determined that the zone backlight value is above a first threshold, to multiply the zone backlight value with a backlight value gain coefficient to obtain a backlight value to which a gain is applied, corresponding to the zone image data block, and to output the backlight value to which the gain is applied, to a driver circuit of backlight source in a backlight zone corresponding to the zone image data block, to control brightness of the backlight source in the corresponding backlight zone as a result of driving, where the backlight value gain coefficient is more than 1; and a zone image grayscale compensating section configured, when it is determined that the zone backlight value is below a second threshold, to compensate for the grayscale values of pixels in the zone image data block using compensation coefficients respectively to obtain compensated image data for driving the liquid crystal panel, wherein the compensation coefficient is more than 1.

Claims

1. An apparatus for controlling liquid crystal display brightness, the apparatus comprising:

a zone image grayscale determining section configured to determine grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal;

a zone backlight value pre-obtaining section configured to pre-obtain a zone backlight value corresponding to the zone image data block according to the grayscale values;

a zone backlight value gain section configured, when it is determined that the zone backlight value is above a first threshold, to multiply the zone backlight value with a backlight value gain coefficient to obtain a backlight value, to which a gain is applied, corresponding to the zone image data block, and to output the backlight value to which the gain is applied to a driver circuit of backlight source in a backlight zone corresponding to the zone image data block to control brightness of the backlight source in the corresponding backlight zone as a result of driving, where the backlight value gain coefficient is more than 1; and

a zone image grayscale compensating section configured, when it is determined that the zone backlight value is below a second threshold, to compensate for the grayscale values of pixels in the zone image data block using compensation coefficients to obtain compensated image data for driving the liquid crystal panel, wherein each of the compensation coefficients is more than 1, and the zone image grayscale compensating section comprises;

a zone grayscale compensation coefficient lookup table determining section configured to determine a grayscale compensation coefficient lookup table corresponding to a zone image data block cluster comprising the zone image data block, wherein all zone image data blocks are determined as a number of the zone image data block clusters, and each of the zone image data block clusters comprises a number of adjacent zone image data blocks; and

a zone grayscale compensation coefficient determining section configured to search the determined grayscale compensation coefficient lookup table for the compensation coefficients using the grayscale values of pixels in the zone image data block.

2. The apparatus according to claim 1, wherein the zone image grayscale compensating section is configured:

to preset a number of grayscale compensation coefficient lookup tables, wherein at least two of the zone image data block clusters correspond to different grayscale compensation coefficient lookup tables in which different relationships between a compensation coefficient and a grayscale value are recorded.

3. The apparatus according to claim 2, wherein a compensation curve of a correspondence relationship between a compensation coefficient and a grayscale value is an inverted “

S”

-like curve, wherein a traversal axis of the inverted “

S”

-like curve represents an input grayscale value, and a vertical axis thereof represents an output grayscale value.

4. The apparatus according to claim 1, wherein the zone backlight value gain section comprises:

a zone image grayscale average calculating section configured to obtain an average grayscale value of pixels in at least one of the zone image data block clusters; and

a zone backlight gain coefficient obtaining module configured to determine the backlight value gain coefficient according to a relationship between the average grayscale value and the backlight value gain coefficient.

5. The apparatus according to claim 4, wherein the zone backlight value gain section is configured:

to preset a number of backlight value gain coefficient lookup tables, wherein at least two of the zone image data block clusters correspond to different backlight value gain coefficient lookup tables in which different relationships between a backlight value gain coefficient and an average grayscale value are recorded.

6. The apparatus according to claim 5, wherein the zone backlight value gain section is configured:

to match a backlight value gain coefficient relationship lookup table to the position where at least one of the zone image data block clusters is distributed on a display area.

7. The apparatus according to claim 6, wherein:

a gain curve between an average grayscale value and a backlight value gain coefficient is recorded in each of the backlight value gain coefficient lookup tables,

wherein the gain curve is divided into a low brightness enhancement interval, a high brightness enhancement interval, and a power control interval while the average grayscale value is increasing, and

wherein the backlight value gain coefficients in the high brightness enhancement interval are more than those in the low brightness enhancement interval and the power control interval.

8. A liquid crystal display device, comprising:

a memory configured to store programs and various data;

an apparatus for controlling liquid crystal display brightness, the apparatus configured to receive an image signal, to process the data, to output 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 to output zone backlight values;

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

a PWM driver unit configured to generate PWM control signals according to the duty ratios to control backlight sources in backlight zones;

wherein the apparatus for controlling liquid crystal display brightness comprises;

a zone image grayscale determining section configured to determine grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal;

a zone backlight value pre-obtaining section configured to pre-obtain a zone backlight value corresponding to the zone image data block according to the grayscale values;

a zone backlight value gain section configured, when it is determined that the zone backlight value is above a first threshold, to multiply the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a backlight value, to which a gain is applied, corresponding to the zone image data block, and to output the backlight value to which the gain is applied to a driver circuit of backlight source in a backlight zone comprising the zone image data block to control brightness of the backlight source in the backlight zone as a result of driving, where the backlight value gain coefficient is more than 1; and

a zone image grayscale compensating section configured, when it is determined that the zone backlight value is below a second threshold, to compensate for the grayscale values of pixels in the zone image data block using compensation coefficients to obtain compensated image data for driving the liquid crystal panel, wherein each of the compensation coefficients is more than 1, and the zone image grayscale compensating section comprises;

a zone grayscale compensation coefficient lookup table determining section configured to determine a grayscale compensation coefficient lookup table corresponding to a zone image data block cluster comprising the zone image data block, wherein all zone image data blocks are determined as a number of the zone image data block clusters, and each of the zone image data block clusters comprises a number of adjacent zone image data blocks; and

a zone grayscale compensation coefficient determining section configured to search the determined grayscale compensation coefficient lookup table for the compensation coefficients using the grayscale values of pixels in the zone image data block.

9. The liquid crystal display device according to claim 8, wherein the zone image grayscale compensating section is configured:

to preset a number of grayscale compensation coefficient lookup tables, wherein at least two zone image data block clusters correspond to different grayscale compensation coefficient lookup tables in which different relationships between a compensation coefficient and a grayscale value are recorded.

10. The liquid crystal display device according to claim 8, wherein the zone backlight value gain section comprises:

a zone image grayscale average calculating section configured to obtain an average grayscale value of all pixels in at least one of the zone image data block clusters; and

a zone backlight gain coefficient obtaining module configured to determine a backlight value gain coefficient according to a relationship between the average grayscale value and the backlight value gain coefficient.

11. The apparatus according to claim 10, wherein the zone backlight value gain section is configured:

to preset a number of backlight value gain coefficient lookup tables, wherein at least two zone image data block clusters correspond to different backlight value lookup tables in which different relationships between a backlight value gain coefficient and an average grayscale value are recorded.

12. A method for controlling liquid crystal display brightness, the method comprising:

determining, by a liquid crystal display device, grayscale values of pixels in a zone image data block under a predetermined rule according to a received image signal, and pre-obtaining a zone backlight value corresponding to the zone image data block according to the grayscale values;

multiplying, by the liquid crystal display device, the zone backlight value with a backlight value gain coefficient to obtain a backlight value, to which a gain is applied, corresponding to the zone image data block when it is determined that the zone backlight value is above a first threshold, and outputting, by the liquid crystal display device, the backlight value to which the gain is applied to a driver circuit of backlight source in a backlight zone corresponding to the zone image data block to control brightness of the backlight source in the backlight zone as a result of driving, wherein the backlight value gain coefficient is more than 1; and

compensating, by the liquid crystal display device, for the grayscale values of pixels in the zone image data block using compensation coefficients to obtain compensated image data for driving a liquid crystal panel when it is determined that the zone backlight value is below a second threshold, wherein each of the compensation coefficients is more than 1.

13. The method according to claim 12, wherein the compensation coefficients are obtained by:

determining, by the liquid crystal display device, a grayscale compensation coefficient lookup table corresponding to a zone image data block cluster comprising the zone image data block, wherein all zone image data blocks are determined as a number of zone image data block clusters, and each of the zone image data block clusters comprises a number of adjacent zone image data blocks; and

searching, by the liquid crystal display device, the determined grayscale compensation coefficient lookup table for the compensation coefficients using the grayscale values of the pixels of in the zone image data blocks.

14. The method according to claim 13, wherein a number of compensation coefficient lookup tables are preset, and at least two of the zone image data block clusters correspond to different compensation coefficient lookup tables in which different relationships between a compensation coefficient and a grayscale value are recorded.

15. The method according to claim 14, wherein:

a compensation curve of a correspondence relationship between a compensation coefficient and a grayscale value is an inverted “

S”

-like curve,

wherein a traversal axis of the inverted “

S”

-like curve represents an input grayscale value, and

wherein a vertical axis of the inverted “

S”

-like curve represents an output grayscale value.

16. The method according to claim 12, wherein the backlight value gain coefficient is obtained by:

obtaining, by the liquid crystal display device, an average grayscale value of pixels in a zone image data block cluster comprising the zone image data block, wherein all zone image data blocks are determined as a number of zone image data block clusters, and each of the zone image data block clusters comprises a number of adjacent zone image data blocks; and

determining, by the liquid crystal display device, the backlight value gain coefficient according to a relationship between the average grayscale value and the backlight value gain coefficient.

17. The method according to claim 16, wherein a number of backlight value gain coefficient lookup tables are preset, and at least two of the zone image data block clusters correspond to different backlight value gain coefficient lookup tables in which different relationships between a backlight value gain coefficient and an average grayscale value are recorded.

18. The method according to claim 17, wherein a gain curve between an average grayscale value and a backlight value gain coefficient is recorded in each of the backlight value gain coefficient lookup tables, wherein the gain curve is divided into a low brightness enhancement interval, a high brightness enhancement interval, and a power control interval while the average grayscale value is increasing, and wherein backlight value gain coefficients in the high brightness enhancement interval are more than those in the low brightness enhancement interval and the power control interval.