DRIVING SYSTEM FOR ACTIVE-MATRIX DISPLAYS

• US 20130201223A1
• Filed: 02/03/2012
• Published: 08/08/2013
• Est. Priority Date: 02/03/2012
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Li, Kongning, Chaji, Gholamreza, Nathan, Arokia, Gupta, Vasudha
• Granted Patent: US 8,937,632 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• 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 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2360/144 the light being ambient light
• 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 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

Raw grayscale image data, representing images to be displayed in successive frames, is used to drive a display having pixels that include a drive transistor and an organic light emitting device by dividing each frame into at least first and second-frames, and supplying each pixel with a drive current that is higher in the first sub-frame than in the second sub-frame for raw grayscale values in a first preselected range, and higher in the second sub-frame than in the first sub-frame for raw grayscale values in a second preselected range. The display may be an active matrix display, such as an AMOLED display.

Claims

1. A method of using raw grayscale image data, representing images to be displayed in successive frames, to drive a display having pixels that include a drive transistor and an organic light emitting device, said method comprising:

dividing each frame into at least first and second-frames, and

supplying each pixel with a drive current that is

higher in said first sub-frame than in said second sub-frame for raw grayscale values in a first preselected range, and

higher in said second sub-frame than in said first sub-frame for raw grayscale values in a second preselected range.

2. The method of claim 1 in which the raw grayscale value for each frame is converted to first and second sub-frame grayscale values for said first and second sub-frames, and the drive current supplied to said pixel during said first and second sub-frames is based on said first and second sub-frame grayscale values.

3. The method of claim 2 in which first and second sub-frame grayscale values are preselected to produce a pixel luminance during that frame that has a predetermined gamma relationship to said raw grayscale value for that frame.

4. The method of claim 1 in which said display is an active matrix display.

5. The method of claim 4 in which said pixels in said active matrix display are OLED pixels.

6. An apparatus for using raw grayscale image data representing images to be displayed in successive frames, to drive a display having an array of pixels that each include a drive transistor and an organic light emitting device, multiple select lines coupled to said array for delivering signals that select when each pixel is to be driven, and multiple data lines for delivering drive signals to the selected pixels, said apparatus comprising:

a source driver coupled to said data lines and including a processing circuit for receiving said raw grayscale image data and adapted to

divide each frame into at least first and second-frames, and

supply each pixel with a drive current that is

higher in said first sub-frame than in said second sub-frame for raw grayscale values in a first preselected range, and

higher in said second sub-frame than in said first sub-frame for raw grayscale values in a second preselected range.

7. The apparatus of claim 6 in which said processing circuit is adapted to convert the raw grayscale value for each frame to first and second sub-frame grayscale values for said first and second sub-frames, and the drive current supplied to said pixel during said first and second sub-frames is based on said first and second sub-frame grayscale values.

8. The apparatus of claim 7 in which first and second sub-frame grayscale values are preselected to produce a pixel luminance during that frame that has a predetermined gamma relationship to said raw grayscale value for that frame.

9. The apparatus of claim 6 in which said display is an active matrix display.

10. The apparatus of claim 9 in which said pixels in said active matrix display are OLED pixels.