Liquid crystal display with illumination control

• US 20050248555A1
• Filed: 10/15/2004
• Published: 11/10/2005
• Est. Priority Date: 05/04/2004
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Daly, Scott J., Feng, Xiao-fan
• Granted Patent: US 8,395,577 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• 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 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• 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

A backlit display with improved dynamic range.

Claims

1. A method for displaying an image on a liquid crystal display comprising:

(a) illuminating a first pixel at a first non-zero illumination level during an initial frame;

(b) illuminating said first pixel at a second non-zero illumination level during a next subsequent frame;

(c) wherein said first pixel is selectively decreased in illumination to another illumination level a plurality of times each of which has a different illumination level after illuminating said first pixel during said initial frame and before illuminating said first pixel during said subsequent frame.

2. The method of claim 1 wherein said another illumination level is less than that which said first pixel is otherwise illuminated to achieve said second illumination level.

3. The method of claim 1 wherein at least one of said another illumination levels is substantially zero.

4. The method of claim 1 wherein said liquid crystal display includes a plurality of addressable light emitting elements.

5. The method of claim 1 wherein said another illumination level is selected based upon the change of said first pixel between two frames.

6. The method of claim 5 wherein said selection is further based upon a set of two thresholds.

7. A method for displaying an image on a liquid crystal display comprising:

(a) illuminating a first pixel at non-zero illumination levels during a plurality of different frames;

(b) wherein said first pixel is decreased in illumination to a decreased illumination level at a rate greater than the after frame rate wherein said decreased illumination level may be selected from a plurality of different levels.

8. The method of claim 7 wherein said liquid crystal display includes a plurality of addressable light emitting elements.

9. The method of claim 7 wherein said decreased illumination level is substantially zero.

10. The method of claim 7 wherein said decreased illumination level is selected based upon the change of said first pixel between two frames.

11. The method of claim 10 wherein said selection is further based upon a set of two thresholds.

12. A method for displaying an image on a liquid crystal display comprising:

(a) illuminating a first pixel at non-zero illumination levels during a plurality of different frames;

(b) wherein said first pixel is periodically decreased in illumination to a value substantially near zero based upon a temporal analysis of said first pixel.

13. The method of claim 12 wherein said value is less than that which said first pixel is otherwise illuminated to achieve a next frame.

14. The method of claim 12 wherein said value is substantially zero.

15. The method of claim 12 wherein said liquid crystal display includes a plurality of addressable light emitting elements.

16. A method for displaying an image on a liquid crystal display comprising:

(a) illuminating a first pixel at a first non-zero illumination level during an initial frame;

(b) illuminating said first pixel at a second non-zero illumination level during a temporally later subsequent frame, wherein said subsequent frame is temporally later than said initial frame;

(c) wherein said first pixel is selectively decreased in illumination to another illumination level, based upon the a temporal change of said first pixel, after illuminating said first pixel during said initial frame and before illuminating said first pixel during said subsequent frame.

17. The method of claim 16 further comprising if said temporal change is less than a first threshold then said another illumination is set to a relatively high level.

18. The method of claim 17 further comprising if said temporal change is greater than a second threshold then said another illumination is set to a relatively low level.

19. The method of claim 18 further comprising if said temporal change is greater than said first threshold and less than said second threshold then said another illumination is set to a relatively intermediate level.

20. A method for displaying an image on a liquid crystal display comprising:

(a) illuminating a first pixel at non-zero illumination levels during a plurality of different frames by providing a state to a liquid crystal material and a state to a light emitting element;

(b) wherein said light emitting element corresponding to said first pixel is decreased in illumination to a decreased illumination level, wherein the liquid crystal material of said display is started to be modified to a new state and after at least 1/10^th of a frame said light emitting element is changed to a corresponding new state to provide the desired illumination level for said first pixel.