Dynamic gamma for a liquid crystal display

• US 7,164,284 B2
• Filed: 10/13/2004
• Issued: 01/16/2007
• Est. Priority Date: 12/18/2003
• 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, Pan, Hao
• Primary Examiner(s): TANG, MINH NHUT
• Application Number:
  US10/965,059
• Publication Number:
  US 20050134302A1
• Time in Patent Office: 825 Days
• Field of Search: 324/770, 345/89, 345/87, 345/205, 345/206, 345/589, 345/204, 345/102, 349/61, 349/42, 349141-144, 349/140, 348/674
• US Class Current: 324/754.23
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10
• CPC Class Codes: G02F 1/1309 Repairing; Testing
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A system for characterizing the temporal luminance response of a liquid crystal display. A liquid crystal display may be forced at an initial time from a first luminance value to a measured second luminance value. The second luminance value may be measured at a predetermined time after the initial time.

Claims

1. A method for determining the response characteristic of a liquid crystal display, said method comprising:

(a) establishing an initial luminance value for said display;

(b) thereafter driving said display to a target luminance value;

(c) after a predetermined time interval, measuring the actual luminance value of said display as a function of said initial luminance value and said target luminance value;

(d) repeating steps (b) and (c) for a plurality of target luminance values;

(e) repeating steps (a) through (d) for a plurality of initial luminance values; and

(f) characterizing a response time of said display based upon said measured actual luminance values.

2. The method of claim 1 where said predetermined time interval is a frame of video.

3. The method of claim 1 using nine said initial luminance values and nine said target luminance values.

4. The method of claim 1 where said characterization of said response time is graphically represented by a plurality of curves plotting measured luminance versus driving luminance, each curve representing an initial luminance value.

5. The method of claim 4 where said characterization of said response time is expressed by the area between the outermost of said plurality of curves.

6. A method for determining a dynamic gamma response characteristic of a liquid crystal display, said method comprising:

(a) overdriving said display;

(b) establishing an initial luminance value for said display;

(d) after a predetermined time interval, measuring the actual luminance value of said display as a function of said initial luminance value and said target luminance value;

(e) repeating steps (c) and (d) for a plurality of target luminance values;

(f) repeating steps (b) through (e) for a plurality of initial luminance values; and

(g) characterizing a response time of said display based upon said measured actual luminance values.

7. The method of claim 6 wherein said predetermined time interval is based upon a integer number of frame time periods.

8. The method of claim 7 wherein said integer is one.

9. The method of claim 6 where said characterization of said response time is graphically represented by a plurality of curves plotting measured luminance versus driving luminance, each curve representing an initial luminance value.

10. The method of claim 9 where said plurality of curves converge over a central linear region and diverge at one or more ends of said linear region, and where said characterization of said response time is expressed by the area between the outermost of said plurality of curves within at least one of said one or more ends of said linear region where said plurality of curves diverge.

11. A presentation of a response characteristic of a liquid crystal display:

(a) a first axis indicating a range of driving values for the luminance of said display;

(b) a second axis indicating luminance values for said display;

(c) a plurality of lines indicated on said presentation measured by said first and second axis, wherein each of said lines provides an indication of a second luminance value at a common first time between a transition from a first luminance value toward said second luminance value, wherein said first time is not based upon the measured luminance of said display.