Liquid crystal display with reduced black level insertion

• US 7,505,018 B2
• Filed: 10/15/2004
• Issued: 03/17/2009
• 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): Hjerpe; Richard
• Assistant Examiner(s): Mandeville; Jason M
• Application Number:
  US10/966,218
• Publication Number:
  US 20050248592A1
• Time in Patent Office: 1,614 Days
• Field of Search: 345/84, 345 87- 89, 345102-103, 349/61, 349/69, 349/70
• US Class Current: 345/89
• 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 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, said method comprising:

(a) illuminating selective ones of a plurality of regions of a display at a first non-zero illumination level during an initial frame;

(b) illuminating said selective ones 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 selective ones are decreased in illumination to an intermediate illumination level, after illuminating said selective ones during said initial frame and before illuminating said selective ones during said subsequent frame, that is less than that which said selective ones are otherwise illuminated to achieve said second illumination level, wherein said intermediate illumination level is limited to a spatial extent less than the full area of said display, and is based on a transient code having a bit length with a first portion and a second portion, said first portion quantifying said intermediate illumination level and said second portion specifying a temporal subframe during which said selective ones are illuminated at said intermediate illumination level.

2. The method of claim 1 wherein said transient code is updated every sequential frame.

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

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

5. The method of claim 1 wherein said decrease in illumination is performed a plurality of times, each time between a respective two subsequent frames.

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

(a) illuminating a plurality of pixels, each within the same region of a display, at non-zero illumination levels during a plurality of different frames;

(b) wherein said plurality of pixels are decreased in illumination level to a diminished illumination level that is less than that which said plurality of pixels are otherwise illuminated to achieve the desired illumination during a next subsequent frame, wherein the decreased said illumination level is limited to a spatial extent comprising a region of said display less than the full area of said display, and is based on a transient code having a bit length with a first portion and a second portion, said first portion quantifying said diminished illumination level and said second portion identifying a temporal subframe during which said plurality of pixels are illuminated at said diminished illumination level.

7. The method of claim 6 wherein said transient code is updated every sequential frame.

8. The method of claim 6 wherein the decreased said illumination level is substantially zero.

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

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

(a) illuminating respective pixels of a display at selective illumination levels during a plurality of different frames; and

(b) wherein an illumination value of a first pixel is periodically decreased to a value substantially near zero at an average temporal rate greater than the average frame rate of said plurality of different frames, wherein the decreased value of said illumination is limited to a spatial extent comprising a region of said display less than the full area of said display, and is based on a transient code having a bit length with a first portion and a second portion, said first portion quantifying said decreased value and said second portion identifying a temporal subframe during which said first pixel is illuminated at said decreased value.

11. The method of claim 10 wherein said transient code is updated every sequential frame.

12. The method of claim 10 wherein the decreased said illumination level is substantially zero.

13. The method of claim 11 wherein the decreased said illumination level is substantially zero.