Apparatus and method for controlling backlight and liquid crystal display

• US 8,400,392 B2
• Filed: 11/20/2007
• Issued: 03/19/2013
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: Saturn Licensing LLC (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kimura, Kazuto, Hayashi, Masatake, Aoki, Tomio, Katsu, Yoshihiro, Asano, Mitsuyasu
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Patel, Sanjiv D
• Application Number:
  US11/986,135
• Publication Number:
  US 20080129680A1
• Time in Patent Office: 1,946 Days
• Field of Search: 345/102, 345/1.3
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• 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 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Disclosed is a backlight control apparatus for controlling a backlight used in a liquid crystal display, the backlight having a lighting area that includes a plurality of blocks in each of which a backlight luminance is individually allowed to change. The apparatus includes a backlight control unit that calculates the backlight luminance of each block so that the absolute value of the difference between a backlight lighting ratio and 1 is at or below a first value, and controls the backlight so as to yield the calculated backlight luminances of the respective blocks, the backlight lighting ratio being the ratio between backlight set values of neighboring blocks.

Claims

1. A backlight control apparatus for controlling a backlight used in a display, the backlight having a lighting area that includes a plurality of blocks, each of the plurality of blocks containing a light source which controls a backlight luminance, the backlight luminance for each of the plurality of blocks individually allowed to change based at least in part on an image signal corresponding to an image to be displayed by the display, the apparatus comprising:

at least one backlight control circuit to receive the image signal and calculate the backlight luminance of each block based at least on the image signal so that an absolute value of a difference between a backlight lighting ratio and 1 is at or below a first value, and to control the backlight so as to yield the calculated backlight luminances of the respective blocks, the backlight lighting ratio being the ratio between backlight set values of neighboring blocks,

wherein the light source of each of the plurality of blocks receives at least one control signal from the at least one backlight control circuit, the at least one control signal controlling the backlight luminance of an associated block.

2. The apparatus according to claim 1, wherein the backlight luminance of each block is calculated so that the absolute value of the difference between 1 and the ratio between the backlight luminances of pixels away from each other by a predetermined distance in the lighting area is at or below a second value.

9. The apparatus according to claim 1, wherein the first value is based on a minimum perceptible luminance change level.

14. The apparatus according to claim 1, wherein the display is a liquid crystal display.

3. A method of controlling a backlight used in a display, the backlight having a lighting area that includes a plurality of blocks, each of the plurality of blocks containing a light source which controls a backlight luminance, the backlight luminance for each of the plurality of blocks individually allowed to change based at least in part on an image signal corresponding to an image to be displayed by the display, the method comprising:

receiving the image signal;

calculating the backlight luminance of each block based at least on the image signal so that an absolute value of a difference between a backlight lighting ratio and 1 is at or below a first value, the backlight lighting ratio being the ratio between backlight set values of neighboring blocks; and

controlling the light source of each of the plurality of blocks so as to yield the calculated backlight luminances of the respective blocks.

4. The method according to claim 3, wherein the backlight luminance of each block is calculated so that the absolute value of the difference between 1 and the ratio between the backlight luminances of pixels away from each other by a predetermined distance in the lighting area is at or below a second value.

10. The method according to claim 3, wherein the first value is based on a minimum perceptible luminance change level.

15. The method according to claim 3, wherein the display is a liquid crystal display.

5. A display comprising:

a backlight that has a lighting area including a plurality of blocks, each of the plurality of blocks containing a light source which controls a backlight luminance, the backlight luminance for each of the plurality of blocks individually allowed to change based at least in part on an image signal corresponding to an image to be displayed by the display and

at least one backlight control circuit to receive the image signal and calculate the backlight luminance of each block based at least on the image signal so that an absolute value of a difference between a backlight lighting ratio and 1 is at or below a first value, and to control the backlight so as to yield the calculated backlight luminances of the respective blocks, the backlight lighting ratio being the ratio between backlight set values of neighboring blocks,

wherein the light source of each of the plurality of blocks receives at least one control signal from the at least one backlight control circuit, the at least one control signal controlling the backlight luminance of an associated block.

6. The display according to claim 5, wherein the backlight luminance of each block is calculated so that the absolute value of the difference between 1 and the ratio between the backlight luminances of pixels away from each other by a predetermined distance in the lighting area is at or below a second value.

11. The display according to claim 5, wherein the first value is based on a minimum perceptible luminance change level.

16. The display according to claim 5, wherein the display is a liquid crystal display.

7. A backlight control apparatus for controlling a backlight used in a display, the backlight having a lighting area that includes a plurality of blocks, each of the plurality of blocks containing a light source which controls a backlight luminance, the backlight luminance for each of the plurality of blocks individually allowed to change based at least in part on an image signal corresponding to an image to be displayed by the display, the apparatus comprising:

at least one processor adapted to receive the image signal and calculate the backlight luminance of each block based at least on the image signal so that an absolute value of a difference between a backlight lighting ratio and 1 is at or below a first value, and to control the backlight so as to yield the calculated backlight luminances of the respective blocks, the backlight lighting ratio being the ratio between backlight set values of neighboring blocks,

wherein the light source of each of the plurality of blocks receives at least one control signal from the at least one processor, the at least one control signal controlling the backlight luminance of an associated block.

12. The apparatus according to claim 7, wherein the first value is based on a minimum perceptible luminance change level.

17. The apparatus according to claim 7, wherein the display is a liquid crystal display.

8. A display comprising:

a backlight that has a lighting area including a plurality of blocks, each of the plurality of blocks containing a light source which controls a backlight luminance, the backlight luminance for each of the plurality of blocks individually allowed to change based at least in part on an image signal corresponding to an image to be displayed by the display; and

at least one processor adapted to receive the image signal and calculate the backlight luminance of each block based at least on the image signal so that an absolute value of a difference between a backlight lighting ratio and 1 is at or below a first value, and to control the backlight so as to yield the calculated backlight luminances of the respective blocks, the backlight lighting ratio being the ratio between backlight set values of neighboring blocks,

wherein the light source of each of the plurality of blocks receives at least one control signal from the at least one processor, the at least one control signal controlling the backlight luminance of an associated block.

13. The display according to claim 8, wherein the first value is based on a minimum perceptible luminance change level.

18. The display according to claim 8, wherein the display is a liquid crystal display.