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

• US 10,127,867 B2
• Filed: 05/19/2016
• Issued: 11/13/2018
• 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): Bibbins, Latanya
• Assistant Examiner(s): Abebe, Sosina
• Application Number:
  US15/158,702
• Publication Number:
  US 20170061896A1
• Time in Patent Office: 908 Days
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• 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

The disclosure provides an apparatus for controlling liquid crystal display brightness, the apparatus pre-obtaining a zone backlight value corresponding to a zone image data block according to grayscale values; if the zone backlight value is above a first threshold, multiplying the pre-obtained zone backlight value with a backlight value gain coefficient, which is more than 1, to a obtain backlight value to which a gain is applied, of a backlight zone corresponding to the zone image data block, outputting the backlight value to which the gain is applied, to a driver circuit of backlight source in the backlight zone to control brightness of the backlight source in the backlight zone as a result of driving; if the zone backlight value is below a second threshold, compensating for the grayscale values of the pixels in the zone image data block using compensation coefficients, each of which is more than 1.

Claims

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

a memory; and

one or more processors, wherein the memory stores one or more computer readable program codes, and the one or more processors are configured to execute the one or more computer readable program codes to perform;

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;

when it is determined that the zone backlight value is above a first threshold, multiplying the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a backlight value, to which a gain is applied, of a backlight zone corresponding to the zone image data block, and outputting the backlight value to which the gain is applied to a driver circuit of a backlight source in the backlight zone 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

when it is determined that the zone backlight value is below a second threshold, compensating for the grayscale values of the 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.

2. The apparatus of claim 1, wherein the one or more processors are further configured to execute the one or more computer readable program codes to perform:

searching a preset grayscale compensation coefficient lookup table for the grayscale compensation coefficients using the grayscale values in the zone image data block, wherein the grayscale compensation coefficient lookup table records correspondence relationships between the grayscale values and the compensation coefficients.

3. The apparatus of claim 2, wherein the one or more processors are further configured to execute the one or more computer readable program codes to perform:

presetting a compensation curve of the correspondence relationships between the grayscale values and the grayscale compensation coefficients as an inverted “

S”

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

S”

-like curve represents an input grayscale value, and a vertical axis of the inverted “

S”

-like curve represents an output grayscale value.

4. The apparatus of claim 1, wherein the one or more processors are further configured to execute the one or more computer readable program codes to obtain the backlight value gain coefficient by:

obtaining an average grayscale value of pixels of an image according to the grayscale values of the image; and

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

5. The apparatus of claim 4, wherein the one or more processors are further configured to execute the one or more computer readable program codes to preset the relationship between the average grayscale value and the backlight value gain coefficient in a backlight value gain coefficient lookup table.

6. The apparatus of claim 5, wherein the one or more processors are further configured to execute the one or more computer readable program codes to make the backlight value gain coefficient lookup table record a gain curve between the average grayscale value of pixels of an image and the backlight value gain coefficient, 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 of the image 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.

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

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;

when it is determined that the zone backlight value is above a first threshold, multiplying the zone backlight value with a backlight value gain coefficient to obtain a backlight value to which a gain is applied, of a backlight zone corresponding to the zone image data block, and outputting the backlight value to which the gain is applied to a driver circuit of a backlight source in the backlight zone 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

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

8. The method of claim 7, wherein the compensation coefficient is obtained by:

searching a preset grayscale compensation coefficient lookup table for the grayscale compensation coefficients using the grayscale values of pixels in the zone image data block, wherein the grayscale compensation coefficient lookup table records correspondence relationships between the grayscale values and the compensation coefficients.

9. The method of claim 8, wherein a compensation curve of the correspondence relationships between the grayscale values and the grayscale compensation coefficients 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 of the inverted “

S”

-like curve represents an output grayscale value.

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

obtaining an average grayscale value of pixels of an image according to the grayscale values of the pixels of the image; and

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

11. The method of claim 8, wherein a relationship between the average grayscale value and the backlight value gain coefficient is preset in a backlight value gain coefficient lookup table.

12. The method of claim 11, wherein the backlight value gain coefficient lookup table records a gain curve between the average grayscale value and the backlight value gain coefficient, 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 of the image 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.

13. A liquid crystal display device, comprising:

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

an apparatus for controlling liquid crystal display brightness, the apparatus configured to execute the programs in the memory, to invoke the various lookup table data according to the executed programs, to receive an image signal, to process data, and 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 to a backlight processing module according to the image signal;

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

wherein the PWM driver module is configured to generate PWM control signals to control backlight sources in backlight zones;

wherein the apparatus for controlling liquid crystal display brightness comprises an apparatus memory and one or more processors, wherein the apparatus memory stores one or more computer readable program codes, 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;

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

when it is determined that the zone backlight value is above a first threshold, multiplying the pre-obtained zone backlight value with a backlight value gain coefficient to obtain s backlight value to which a gain is applied, of a backlight zone corresponding to the zone image data block, and outputting the backlight value to which the gain is applied to a driver circuit of backlight source in the backlight zone 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

when it is determined that the zone backlight value is below a second threshold, compensating 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, wherein each of the compensation coefficients is more than 1.

14. The liquid crystal display device of claim 13, wherein the one or more processors are further configured to execute the one or more computer readable program codes to perform:

searching a preset grayscale compensation coefficient lookup table for the grayscale compensation coefficients using the grayscale values in the zone image data block, wherein the grayscale compensation coefficient lookup table records correspondence relationships between the grayscale values and the compensation coefficients.

15. The apparatus of claim 14, wherein the one or more processors are further configured to execute the one or more computer readable program codes to perform:

presetting a compensation curve of the correspondence relationships between the grayscale values and the grayscale compensation coefficients as an inverted “

S”

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

S”

-like curve represents an input grayscale value, and a vertical axis of the inverted “

S”

-like curve represents an output grayscale value.

16. The apparatus of claim 13, wherein the one or more processors are further configured to execute the one or more computer readable program codes to obtain the backlight value gain coefficient by:

obtaining an average grayscale value of pixels of an image according to the grayscale values of the image; and

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

17. The apparatus of claim 16, wherein the one or more processors are further configured to execute the one or more computer readable program codes to preset the relationship between the average grayscale value and the backlight value gain coefficient in a backlight value gain coefficient lookup table.

18. The apparatus of claim 17, wherein the one or more processors are further configured to execute the one or more computer readable program codes to make the backlight value gain coefficient lookup table record a gain curve between the average grayscale value of pixels of an image and the backlight value gain coefficient, 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 of the image 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 respectively.