Backlight brightness control method, apparatus, and liquid crystal display device

• US 10,210,822 B2
• Filed: 11/17/2017
• Issued: 02/19/2019
• Est. Priority Date: 05/18/2015
• Status: Active Grant

• Current Assignee: Hisense Electric Co., Ltd. (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.)
• Original Assignee: Hisense Electric Co., Ltd. (Qingdao Huatong State-Owned Capital Operation (Group) Co., Ltd.)
• Inventors: Zhang, Yuxin, Song, Zhicheng, Wu, Shaowei
• Primary Examiner(s): Karimi, Pegeman
• Application Number:
  US15/816,416
• Publication Number:
  US 20180075813A1
• Time in Patent Office: 459 Days
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• 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 3/34 by control of light from an independent source
• 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

Disclosed are a method and apparatus for controlling backlight brightness, and a liquid crystal display device, and the method for controlling backlight brightness includes: determining a backlight duty ratio of each backlight zone according to a backlight value of each backlight zone; determining a gain backlight current value of a backlight area according to an average backlight value of the backlight area, and a preset gain curve, wherein each backlight area corresponds to at least one backlight driving chip, and the at least one backlight driving chip controls in parallel more than one backlight zones in the backlight area corresponding to the at least one driving chip; generating a pulse modulation signal of each backlight zone according to the backlight duty ratio of corresponding backlight zone and the gain backlight current value; and adjusting a backlight current of the corresponding backlight zone according to the pulse modulation signal.

Claims

1. A method for controlling backlight brightness, applicable to a backlight module comprising a plurality of backlight zones, each of which comprises one or more point light sources, the method comprising:

determining a backlight duty ratio of each backlight zone according to a backlight value of each backlight zone, wherein the backlight value of each backlight zone is determined by brightness data of an image zone corresponding to the backlight zone;

determining a gain backlight current value of a backlight area according to an average backlight value of the backlight area and a preset gain curve, wherein each backlight area corresponds to at least one backlight driving chip, and the at least one backlight driving chip controls in parallel more than one backlight zone in the backlight area corresponding to the at least one backlight driving chip;

generating a pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value; and

adjusting a backlight current of the corresponding backlight zone according to the pulse modulation signal.

2. The method according to claim 1, wherein before generating the pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value, the method further comprises:

generating a driving signal including gain backlight current value information and backlight duty ratio information, according to the gain backlight current value of the backlight area and the backlight duty ratio of each backlight zone in the backlight area;

wherein the gain backlight current value information corresponds to information of the gain backlight current value, and the backlight duty ratio information corresponds to information of the backlight duty ratio.

3. The method according to claim 2, wherein generating the pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value comprises:

determining a magnitude of a peak of the pulse modulation signal by adjusting a reference voltage according to the gain backlight current value information of the driving signal; and

determining a duty ratio of the pulse modulation signal according to the backlight duty ratio information of the driving signal.

4. The method according to claim 1, wherein the plurality of backlight areas correspond to at least two different preset gain curves, and wherein a gain amplitude of a preset gain curve corresponding to a backlight area located in a central area of the backlight module is higher than gain amplitudes of preset gain curves corresponding to other backlight areas.

5. The method according to claim 1, wherein determining the gain backlight current value of the backlight area according to the average backlight value of the backlight area, and the preset gain curve comprises:

searching for a gain corresponding to the average backlight value of each backlight area according to the average backlight value of the backlight area and a preset gain curve; and

multiplying a backlight current value of the backlight area with the found gain to obtain the gain backlight current value of the backlight area.

6. The method according to claim 1, wherein before generating the pulse modulation signal of each backlight zone according to the backlight duty ratio of corresponding backlight zone and the gain backlight current value, the method further comprises:

when it is determined that a difference between the gain backlight current value and a present backlight current value is above a first preset threshold, marking the gain backlight current value as valid so that a magnitude of a peak of reference voltage in the backlight driving chip corresponding to the backlight area is adjusted subsequently with the gain backlight current value; and

when it is determined that the difference between the gain backlight current value and the present backlight current value is not above the first preset threshold, marking the gain backlight current value as invalid so that the magnitude of the peak of reference voltage in the backlight driving chip corresponding to the backlight area is not adjusted subsequently.

7. The method according to claim 1, wherein after the determining the gain backlight current value of the backlight area, the method further includes:

when it is determined that an the average backlight brightness is obtained according to a currently determined backlight duty ratio of each backlight zone, and the gain backlight current value of the backlight area is above a second preset threshold, invoking and searching a preset power adjustment curve for a power adjustment coefficient corresponding to the currently obtained backlight brightness of the backlight area, and multiplying the gain backlight current value with the power adjustment coefficient to obtain a revised backlight current value; and

generating the pulse modulation signal of each backlight zone according to the revised backlight current value of the backlight area and the backlight duty ratios of corresponding backlight zones in the backlight area.

8. The method according to claim 7, wherein before the pulse modulation signal of each backlight zone is generated according to the revised backlight current value of the backlight area and the backlight duty ratio of the corresponding backlight zone in the backlight area, the method further comprises:

when it is determined that a difference between the revised backlight current value and a present backlight current value is above a first preset threshold, marking the revised backlight current value as valid so that a magnitude of a peak of reference voltage in the backlight driving chip corresponding to the backlight area is adjusted subsequently with the revised backlight current value; and

when it is determined that the difference between the revised backlight current value and the present backlight current value is not above the first preset threshold, marking the revised backlight current value as invalid so that the magnitude of the peak of reference voltage in the backlight driving chip corresponding to the backlight area is not adjusted subsequently.

9. An apparatus for controlling backlight brightness, applicable to a backlight module comprising a plurality of backlight zones, each of which comprises one or more point light sources, the apparatus comprising:

a backlight processor configured to determine a backlight duty ratio of each backlight zone according to a backlight value of each backlight zone, wherein the backlight value of each backlight zone is determined by brightness data of an image zone corresponding to the backlight zone, and the backlight processor configured to determine a gain backlight current value of a backlight area according to an average backlight value of the backlight area and a preset gain curve, wherein each backlight area corresponds to at least one backlight driving chip, and the at least one backlight driving chip controls in parallel more than one backlight zones in the backlight area corresponding to the at least one backlight driving chip;

wherein the at least one backlight driving chip is configured to generate a pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value, and to send the pulse modulation signal to a backlight driving circuit; and

wherein the backlight driving circuit is configured to adjust a backlight current of the corresponding backlight zone according to the pulse modulation signal.

10. The apparatus according to claim 9, wherein before the backlight processor is configured to generate the pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value, the backlight processor is further configured to generate a driving signal including gain backlight current value information and backlight duty ratio information, according to the gain backlight current value of the backlight area and the backlight duty ratio of each backlight zone in the backlight area;

wherein the gain backlight current value information corresponds to information of the gain backlight current value, and the backlight duty ratio information corresponds to information of the backlight duty ratio.

11. The apparatus according to claim 9, wherein the backlight driving chip configured to generate the pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value is further configured:

to determine a magnitude of the peak of the pulse modulation signal by adjusting a reference voltage according to the gain backlight current value information of the driving signal; and

to determine a duty ratio of the pulse modulation signal according to the backlight duty ratio information of the driving signal.

12. The apparatus according to claim 9, wherein the plurality of backlight areas in the backlight module correspond to at least two different preset gain curves, and wherein a gain amplitude of a preset gain curve corresponding to a backlight area located in a central area of the backlight module is higher than gain amplitudes of preset gain curves corresponding to other backlight areas.

13. The apparatus according to claim 9, wherein the backlight processor configured to determine the gain backlight current value of the backlight area according to the average backlight value of the backlight area and the preset gain curve is further configured:

to search for a gain corresponding to the average backlight value of each backlight area according to the average backlight value of the backlight area and a preset gain curve; and

;

to multiply a backlight current value of the backlight area with the found gain to obtain the gain backlight current value of the backlight area.

14. The apparatus according to claim 9, wherein before the backlight processor is configured to generate the pulse modulation signal of each backlight zone according to the backlight duty ratio of corresponding backlight zone and the gain backlight current value, the backlight processor is further configured:

when it is determined that a difference between the gain backlight current value and a present backlight current value is above a first preset threshold, to mark the gain backlight current value as valid so that a magnitude of a peak of reference voltage in the backlight driving chip corresponding to the backlight area is adjusted subsequently with the gain backlight current value; and

when it is determined that the difference between the gain backlight current value and the present backlight current value is not above the first preset threshold, to mark the gain backlight current value as invalid so that the magnitude of the peak of reference voltage in the backlight driving chip corresponding to the backlight area is not adjusted subsequently.

15. A liquid crystal display device, comprising a liquid crystal screen and an apparatus for controlling backlight brightness applicable to a backlight module comprising a plurality of backlight zones, each of which comprises one or more point light sources, the apparatus comprising:

a backlight processor configured to determine a backlight duty ratio of each backlight zone according to a backlight value of each backlight zone, wherein the backlight value of each backlight zone is determined by brightness data of an image zone corresponding to the backlight zone, and the backlight processor configured to determine a gain backlight current value of a backlight area according to an average backlight value of the backlight area and a preset gain curve, wherein each backlight area corresponds to at least one backlight driving chip, and the at least one of the backlight driving chip controls in parallel more than one backlight zones in the backlight area corresponding to the at least one backlight driving chip;

wherein the at least one backlight driving chip is configured to generate a pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value, and to send the pulse modulation signal to a backlight driving circuit; and

wherein the backlight driving circuit is configured to adjust a backlight current of the corresponding backlight zone according to the pulse modulation signal.

16. The liquid crystal display device according to claim 15, wherein the plurality of backlight areas in the backlight module correspond to at least two different preset gain curves, and wherein a gain amplitude of a preset gain curve corresponding to a backlight area located in a central area of the backlight module is higher than gain amplitudes of preset gain curves corresponding to other backlight areas.

17. The liquid crystal display device according to claim 15, wherein the backlight processor configured to determine the gain backlight current value of the backlight area according to the average backlight value of the backlight area and the preset gain curve is further configured:

to search for a gain corresponding to the average backlight value of each backlight area according to the average backlight value of the backlight area and a preset gain curve; and

to multiply a backlight current value of the backlight area with the found gain to obtain the gain backlight current value of the backlight area.

18. The liquid crystal display device according to claim 15, wherein before the backlight processor is configured to generate the pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the gain backlight current value, the backlight processor is further configured:

when it is determined that a difference between the gain backlight current value and a present backlight current value is above a first preset threshold, to mark the gain backlight current value as valid so that a magnitude of a peak of reference voltage in the backlight driving chip corresponding to the backlight area is adjusted subsequently with the gain backlight current value; and

when it is determined that the difference between the gain backlight current value and the present backlight current value is not above the first preset threshold, to mark the gain backlight current value as invalid so that the magnitude of the peak of reference voltage in the backlight driving chip corresponding to the backlight area is not adjusted subsequently.

19. The liquid crystal display device according to claim 15, wherein after the backlight processor is configured to determine the gain backlight current value of the backlight area, the backlight processor is further configured:

when it is determined that an average backlight brightness is obtained according to a currently determined backlight duty ratio of each backlight zone, and the gain backlight current value is above a second preset threshold, to invoke and search a preset power adjustment curve for a power adjustment coefficient corresponding to the currently obtained backlight brightness of the backlight area, and to multiply the gain backlight current value with the power adjustment coefficient to obtain a revised backlight current value; and

wherein the backlight driving chip is further configured to generate the pulse modulation signal of each backlight zone according to the backlight duty ratio of the corresponding backlight zone and the revised backlight current value.

20. The liquid crystal display device according to claim 19, wherein before the pulse modulation signal of each backlight zone is generated according to the revised backlight current value of the backlight area and the backlight duty ratio of the corresponding backlight zone in the backlight area, the backlight processor is further configured:

when it is determined that a difference between the revised backlight current value and a present backlight current value is above a first preset threshold, to mark the revised backlight current value as valid so that a magnitude of a peak of reference voltage in the backlight driving chip corresponding to the backlight area is adjusted subsequently with the revised backlight current value; and

when it is determined that the difference between the revised backlight current value and the present backlight current value is not above the first preset threshold, to mark the revised backlight current value as invalid so that the magnitude of reference voltage in the backlight driving chip corresponding to the pulse signal of the backlight area is not adjusted subsequently.