Liquid crystal display with temporal black point

• US 7,872,631 B2
• Filed: 10/15/2004
• Issued: 01/18/2011
• Est. Priority Date: 05/04/2004
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Nguyen; Chanh
• Assistant Examiner(s): Snyder; Adam J
• Application Number:
  US10/966,979
• Publication Number:
  US 20050248520A1
• Time in Patent Office: 2,286 Days
• Field of Search: 345/46, 345 87-107, 345/204, 345/690, 345/691, 349/61
• US Class Current: 345/102
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0613 The adjustment depending on the type of the information to be displayed
• 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 2330/10 Dealing with defective pixels
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A backlit display with improved dynamic range. The disclosed display illuminates a pixel of the display at respective non-zero illumination levels during each of a first frame and a second frame and decreases the illumination level of the pixel during the interval between the first frame and the second frame.

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 subsequent frame, wherein said subsequent frame is temporally later than said initial frame;

(c) wherein said first pixel is selectively decreased in illumination to an intermediate illumination level, where the luminance magnitude of said intermediate illumination level, maintained over an interval beginning after illuminating said first pixel during said initial frame and ending before illuminating said first pixel during said subsequent frame, is automatically selected based upon a predicted amount of temporal blur, prediction of said temporal blur being based on measurements of an input image signal limited to a region local to said first pixel, measured after modifying said input image signal by a point spread function of a backlight of said display as modified by a diffusion layer, said point spread function stored in memory accessible to said display.

2. The method of claim 1 wherein said intermediate 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 said intermediate illumination level is substantially zero.

4. The method of claim 1 wherein the selective decrease in illumination to an intermediate illumination level, resulting from said predicted amount of temporal blur, is isolated to said region.

5. The method of claim 1 wherein said temporal blur is based upon moving edges.

6. The method of claim 1 wherein said temporal blur is based upon content of at least one of said frames.

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 having a luminance magnitude, maintained over an interval beginning after illuminating said first pixel during said initial frame and ending before illuminating said first pixel during a next subsequent frame, automatically selected based upon a predicted amount of temporal blur, prediction of said temporal blur being based on measurements of an input image signal limited to a region local to said first pixel, measured after modifying said input image signal by a point spread function of a backlight of said display as modified by a diffusion layer, said point spread function stored in memory accessible to said display.

8. The method of claim 7 wherein the decrease in illumination to an intermediate illumination level, resulting from said predicted amount of temporal blur, is isolated to said region.

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

10. The method of claim 7 wherein said temporal blur is based upon moving edges.

11. The method of claim 7 wherein said temporal blur is based upon content of at least one of said frames.

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 during at least one first interval between a respective pair of said plurality of frames, and where said first pixel is not decreased in illumination to said value substantially near zero during at least one second interval between a respective pair of said respective plurality of frames based upon a predicted amount of temporal blur, prediction of said temporal blur being based on measurements of an input image signal limited to a region local to said first pixel, measured after modifying said input image signal by a point spread function of a backlight of said display as modified by a diffusion layer, said point spread function stored in memory accessible to said display.

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 the decrease in illumination to an intermediate illumination level, resulting from said predicted amount of temporal blur, is isolated to said region.

16. The method of claim 12 wherein said temporal blur is based upon moving edges.

17. The method of claim 12 wherein said temporal blur is based upon content of at least one of said frames.