IMAGE DISPLAY APPARATUS AND CONTROL METHOD THEREOF

• US 20140055505A1
• Filed: 08/26/2013
• Published: 02/27/2014
• Est. Priority Date: 08/27/2012
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Inamura, Kohei, Tada, Mitsuru, Uchiike, Hiroshi, Ikeda, Takeshi
• Granted Patent: US 9,501,965 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• 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 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• 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 3/22 using controlled light sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

An image display apparatus according to the present invention, includes: a light-emitting unit capable of separately controlling emission brightness in each of a plurality of divided regions in a screen; a determining unit configured to determine target brightness of a predetermined divided region, based on image data corresponding to the predetermined divided region; an estimating unit configured to estimate brightness of the predetermined divided region when light is emitted by the light-emitting unit at emission brightness which is based on image data in each of the plurality of divided regions; and a control unit configured to control emission brightness of two or more divided regions including the predetermined divided region based on a difference between the target brightness determined by the determining unit and the brightness estimated by the estimating unit.

Claims

1. An image display apparatus comprising:

a light-emitting unit capable of separately controlling emission brightness in each of a plurality of divided regions in a screen;

a determining unit configured to determine target brightness of a predetermined divided region, based on image data corresponding to the predetermined divided region;

an estimating unit configured to estimate brightness of the predetermined divided region when light is emitted by the light-emitting unit at emission brightness which is based on image data in each of the plurality of divided regions; and

a control unit configured to control emission brightness of two or more divided regions including the predetermined divided region based on a difference between the target brightness determined by the determining unit and the brightness estimated by the estimating unit.

2. The image display apparatus according to claim 1, wherein

the predetermined divided region is a divided region where the estimated brightness is lower than the target brightness.

3. The image display apparatus according to claim 1, wherein

the predetermined divided region is a region where the estimated brightness is lower than the target brightness, and a difference between the estimated brightness and the target brightness is maximum.

4. The image display apparatus according to claim 1, wherein

the control unit increases emission brightness for at least one divided region that is adjacent to the predetermined divided region at an increase rate in accordance with an increase rate of emission brightness for the predetermined divided region.

5. The image display apparatus according to claim 1, wherein

the control unit increases emission brightness for at least one divided region that is adjacent to the predetermined divided region at an increase rate that is approximately equal to an increase rate of emission brightness for the predetermined divided region.

6. The image display apparatus according to claim 1, wherein

the control unit increases emission brightness for all divided regions at an increase rate in accordance with an increase rate of emission brightness for the predetermined divided region.

7. The image display apparatus according to claim 1, wherein

the control unit increases emission brightness for all divided regions at an increase rate that is approximately equal to an increase rate of emission brightness for the predetermined divided region.

8. The image display apparatus according to claim 1, further comprising:

a brightness distribution estimating unit configured to estimate a brightness distribution when light is emitted by the light-emitting unit at the emission brightness determined by the control unit; and

a correcting unit configured to correct image data based on the brightness distribution estimated by the brightness distribution estimating unit.

9. The image display apparatus according to claim 1, wherein

the control unit controls emission brightness so that brightness equals or exceeds the target brightness at all positions in the predetermined divided region.

10. The image display apparatus according to claim 1, further comprising:

a current amount determining unit configured to determine whether or not a required current amount that is an amount of current necessary for emitting light by the light-emitting unit at the emission brightness determined by the control unit is greater than a predetermined current amount, wherein

when the current amount determining unit determines that the required current amount is greater than the predetermined current amount, the control unit performs an adjustment process for adjusting the emission brightness so that the required current amount equals or falls below the predetermined current amount.

11. The image display apparatus according to claim 10, further comprising:

a region detecting unit configured to detect a divided region with a difference in target brightness from surrounding divided regions that is equal to or greater than a threshold, as an isolated high-brightness region, wherein

the adjustment process is a process of increasing emission brightness of divided regions surrounding the isolated high-brightness region detected by the region detecting unit and reducing emission brightness of other divided regions, so that the required current amount equals or falls below the predetermined current amount and brightness of each of the divided regions equals or exceeds the target brightness.

12. The image display apparatus according to claim 10, wherein

the adjustment process is a process of lowering the emission brightness of each of the divided regions determined by the control unit, at an approximately equal lowering rate.

13. The image display apparatus according to claim 11, wherein

the adjustment process is a process of adjusting the emission brightness of each of the divided regions determined by the control unit, based on a difference between the required current amount and the predetermined current amount.

14. The image display apparatus according to claim 10, wherein

the adjustment process is a process of setting emission brightness of the predetermined divided region to emission brightness that is higher than the emission brightness based on image data and setting emission brightness of other divided regions to a value that is approximately equal to the emission brightness based on image data, so that brightness of each of the divided regions equals or exceeds the target brightness.

15. The image display apparatus according to claim 14, wherein

the adjustment process is a process of adjusting the emission brightness of each of the divided regions determined by the control unit, based on a difference between the estimated brightness and the target brightness.

16. The image display apparatus according to claim 10, wherein

when the required current amount does not equal or fall below the predetermined current amount even when repetitively performing the adjustment process a predetermined number of times, the control unit controls emission brightness to a value determined in advance so that the required current amount equals or falls below the predetermined current amount.

17. The image display apparatus according to claim 11, further comprising:

a scene change detecting unit configured to detect changing of scenes in image data inputted in frame units, wherein

the adjustment process for one frame is not always completed within a period of the frame, and

after the required current amount is determined to be greater than the predetermined current amount by the current amount determining unit and until changing of scenes is detected by the scene change detecting unit,

the control unit;

performs a first adjustment process that is the adjustment process and a second adjustment process of lowering the emission brightness of each of the divided regions determined by the control unit, at an approximately equal lowering rate;

controls emission brightness for a present frame to a value which is a result of the second adjustment process for the present frame, when a frame for which the first adjustment process has been completed does not exist among frames inputted after the current amount determining unit determines that the required current amount is greater than the predetermined current amount and until the present; and

controls the emission brightness for the present frame to a value which is a latest result of the first adjustment process, when a frame for which the first adjustment process has been completed exists among frames inputted after the current amount determining unit determines that the required current amount is greater than the predetermined current amount and until the present.

18. The image display apparatus according to claim 17, wherein

at least one of the first adjustment process and the second adjustment process is a process of adjusting the emission brightness determined by the control unit, based on a difference between the required current amount and the predetermined current amount.

19. A control method for an image display apparatus including light-emitting unit capable of separately controlling emission brightness in each of a plurality of divided regions in a screen, the control method comprising:

determining target brightness of a predetermined divided region, based on image data corresponding to the predetermined divided region;

estimating brightness of the predetermined divided region when light is emitted by the light-emitting unit at emission brightness which is based on image data in each of the plurality of divided regions; and

controlling emission brightness of two or more divided regions including the predetermined divided region based on a difference between the target brightness determined in the determining and the brightness estimated in the estimating.