METHOD AND APPARATUS FOR CONTROLLING LIQUID CRYSTAL DISPLAY BRIGHTNESS, AND LIQUID CRYSTAL DISPLAY DEVICE

• US 20170110064A1
• Filed: 06/05/2016
• Published: 04/20/2017
• Est. Priority Date: 10/16/2015
• Status: Active Grant

• Current 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)
• 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: Zhang, Yuxin, Huang, Shunming, Song, Zhicheng
• Granted Patent: US 10,181,294 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• 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 3/36 using liquid crystals

Abstract

This disclosure provides a method and apparatus for controlling liquid crystal display brightness, and a liquid crystal display device, and relates to the field of liquid crystal display technologies, where the method includes: determining grayscale values of all 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 the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a backlight value of a backlight zone corresponding to the zone image data block to which a gain is applied, wherein the backlight value gain coefficient is more than 1; and outputting the backlight value of the backlight zone to a driver circuit of backlight source in the backlight zone to control the brightness of the backlight source in the backlight zone as a result of driving, thus improving the effect of contrast quality of pictures displayed by the liquid crystal display device.

Claims

1. 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 of the pixels in the zone image data block;

multiplying, by the liquid crystal display device, the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a backlight value of a backlight zone corresponding to the zone image data block to which a gain is applied, wherein the backlight value gain coefficient is more than 1;

determining, by the liquid crystal display device, a backlight gain adjustment factor as a function of ambient luminance, and multiplying the zone backlight value of the backlight zone to which the gain is applied, with the backlight gain adjustment factor to obtain an adjusted backlight value of the backlight zone to which the gain is applied; and

outputting, by the liquid crystal display device, the adjusted backlight value of the backlight zone to which the gain is applied to a driver circuit of backlight source in the backlight zone to control the brightness of the backlight source in the backlight zone as a result of driving.

2. The method according to claim 1, wherein a relationship between the backlight gain adjustment factor and the ambient luminance is set so that:

the backlight gain adjustment factor becomes larger with a larger ambient luminance value.

3. The method according to claim 1, wherein the backlight gain adjustment factor is determined by:

dividing, by the liquid crystal display device, different ambient luminance values into several intervals, each of the intervals corresponds to a value of the backlight gain adjustment factor.

4. The method according to claim 1, wherein the backlight gain adjustment factor is determined by:

presetting, by the liquid crystal display device, a linear function relationship between a backlight gain adjustment factor α and

an ambient luminance value E as α

=α

₀+k*E, wherein α

₀ represents a constant, and k represents a variation rate at which the backlight gain adjustment factor α

varies with the ambient luminance value E.

5. The method according to claim 1, wherein the backlight value gain coefficient is obtained by:

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

6. The method according to claim 5, wherein the relationship between the average grayscale value and the backlight value gain coefficient is determined by:

presetting, by the liquid crystal display device, a number of backlight value gain coefficient lookup tables so that at least two zone image data block clusters correspond to different backlight value gain coefficient lookup tables in which different relationships between the backlight value gain coefficient and the average grayscale value of all the pixels in the zone image data block cluster are recorded; and

matching, by the liquid crystal display device, a gain coefficient relationship lookup table to a position where the zone image data block cluster is distributed on a display area;

wherein a gain curve between the average grayscale value of all the pixels in the zone image data block cluster and the backlight value gain coefficient is recorded in each of the backlight value gain coefficient lookup tables, and the gain curve is divided sequentially into a low brightness enhancement interval, a high brightness enhancement interval, and a power control interval while the average grayscale value is increasing, 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.

7. 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 of pixels in the zone image data block;

a zone backlight value gain section configured to multiply the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a hack light value of a backlight zone corresponding to the zone image data block to which a gain is applied, wherein the backlight value gain coefficient is more than 1;

a backlight value gain adjusting section configured to determine a backlight gain adjustment factor as a function of ambient luminance, and to multiply the zone backlight value of the backlight zone to which the gain is applied, with the backlight gain adjustment factor to obtain an adjusted backlight value of the backlight zone to which the gain is applied; and

a zone backlight value outputting section configured to output the adjusted backlight value of the backlight zone to which the gain is applied to a driver circuit of backlight source in the backlight zone to control the brightness of the backlight source in the backlight zone as a result of driving.

8. The apparatus according to claim 7, wherein the backlight value gain adjusting section is configured to determine the backlight gain adjustment factor so that the backlight gain adjustment factor becomes larger with a larger ambient luminance value.

9. The apparatus according to claim 7, wherein the backlight value gain adjusting section configured to determine the backlight gain adjustment factor is configured to divide different ambient luminance values into several intervals, each of the intervals corresponds to a value of the backlight gain adjustment factor.

10. The apparatus according to claim 7, wherein the backlight value gain adjusting section configured to determine the backlight gain adjustment factor is configured to determine a linear function relationship between a backlight gain adjustment factor α

and an ambient luminance value E as α

=α

₀+k*E, wherein α

₀ represents a constant, and k represents a variation rate at which the backlight gain adjustment factor α

varies with the ambient luminance value E.

11. The apparatus according to claim 7, 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 a zone image data block cluster, wherein all zone image data blocks are determined as a number of the zone image data block clusters, each of the zone image data block clusters comprises a number of adjacent zone image data blocks; 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.

12. The apparatus according to claim 11, wherein the zone backlight gain coefficient obtaining module is configured to determine the relationship between the average grayscale value and the backlight value gain coefficient is configured:

to preset a number of backlight value gain coefficient lookup tables so that at least two zone image data block clusters correspond to different backlight value gain coefficient lookup tables in which different relationships between the backlight value gain coefficient and the average grayscale value of all the pixels in the zone image data block cluster are recorded; and

to match a gain coefficient relationship lookup table to a position where the zone image data block cluster is distributed on a display area;

wherein a gain curve between the average grayscale value of all the pixels in the zone image data block cluster and the backlight value gain coefficient is recorded in each of the backlight value gain coefficient lookup tables, and the gain curve is divided sequentially into a low brightness enhancement interval, a high brightness enhancement interval, and a power control interval while the average grayscale value is increasing, 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.

13. The apparatus according to claim 7, wherein the apparatus further comprises:

a backlight value revising section configured, when the average grayscale value of all the pixels in the zone image data block cluster is below a first threshold, to multiply the zone backlight value to which the gain is applied, with a revision coefficient to obtain an adjusted zone backlight value to which the gain is applied, wherein the revision coefficient is determined as a function of dispersity of image brightness distribution, and the revision coefficient is less than 1; and

the zone backlight value outputting section is further configured to output the adjusted zone backlight value of the backlight zone to which the gain is applied, to the driver circuit of the backlight source in the backlight zone to control the brightness of the backlight source in the backlight zone as a result of driving.

14. 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 configured 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

further configured to output zone backlight values to a backlight processing unit according to the image signal;

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

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

wherein the apparatus for controlling liquid crystal display brightness comprises;

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

a zone backlight value gain section configured to multiply the pre-obtained zone backlight value with a backlight value gain coefficient to obtain a backlight value of a backlight zone corresponding to the zone image data block to which a gain is applied, wherein the backlight value gain coefficient is more than 1;

a backlight value gain adjusting section configured to determine a backlight gain adjustment factor as a function of ambient luminance, and to multiply the zone backlight value of the backlight zone to which the gain is applied, with the backlight gain adjustment factor to obtain an adjusted backlight value of the backlight zone to which the gain is applied; and

a zone backlight value outputting section configured to output the adjusted backlight value of the backlight zone to which the gain is applied to a driver circuit of backlight source in the backlight zone to control the brightness of the backlight source in the backlight zone as a result of driving.

15. The liquid crystal display device according to claim 14, wherein the backlight value gain adjusting section is configured to determine the backlight in adjustment factor so that the backlight gain adjustment factor becomes larger with a larger ambient luminance value.

16. The liquid crystal display device according to claim 14, wherein the backlight value gain adjusting section configured to determine the backlight gain adjustment factor is configured to divide different ambient luminance values into several intervals, each of the intervals corresponds to a value of the backlight gain adjustment factor.

17. The liquid crystal display device according to claim 14, wherein the backlight value gain adjusting section configured to determine the backlight gain adjustment factor is configured to determine a linear function relationship between a backlight gain adjustment factor α

and an ambient luminance value E as α

=α

₀+k*E, wherein α

₀ represents a constant, and k represents a variation rate at which the backlight gain adjustment factor α

varies with the ambient luminance value E.

18. The liquid crystal display device according to claim 14, 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 a zone image data block cluster, wherein all zone image data blocks are determined as a number of the zone image data block clusters, each of which comprises a number of adjacent zone image data blocks; 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.

19. The liquid crystal display device according to claim 18, wherein the zone backlight gain coefficient obtaining module configured to determine the average grayscale value and the backlight value gain coefficient is configured:

to preset a number of backlight value gain coefficient lookup tables so that at least two zone image data block clusters correspond to different backlight value gain coefficient lookup tables in which different relationships between the backlight value gain coefficient and the average grayscale value of all the pixels in the zone image data block clusters are recorded; and

to match a gain coefficient relationship lookup table to a position where a zone image data block cluster is distributed on a display area;

wherein a gain curve between the average grayscale value of all the pixels in the zone image data block cluster and the backlight value gain coefficient is recorded in each of the backlight value gain coefficient lookup tables, and the gain curve is divided sequentially into a low brightness enhancement interval, a high brightness enhancement interval, and a power control interval while the average grayscale value is increasing, wherein gain coefficients in the high brightness enhancement interval are more than those in the low brightness enhancement interval and the power control interval respectively.

20. The liquid crystal display device according to claim 14, wherein the apparatus for controlling liquid crystal display brightness further comprises:

a backlight value revising section configured, when the average grayscale value of all the pixels in the zone image data block cluster is below a first threshold, to multiply the zone backlight value to which the gain is applied, with a revision coefficient to obtain an adjusted zone backlight value to which the gain is applied, wherein the revision coefficient is determined as a function of dispersity of image brightness distribution, and the revision coefficient is less than 1; and

the zone backlight value outputting section is further configured to output the adjusted zone backlight value of the backlight zone to which the gain is applied, to the driver circuit of the backlight source in the backlight zone to control the brightness of the backlight source in the backlight zone as a result of driving.