COMPENSATION TECHNIQUE FOR COLOR SHIFT IN DISPLAYS

• US 20160005350A1
• Filed: 07/13/2015
• Published: 01/07/2016
• Est. Priority Date: 06/16/2009
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza, Dionne, Joseph Marcel, Hormati, Abbas, Liu, Tong, Alexander, Stefan, Nathan, Arokia
• Granted Patent: US 9,418,587 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• 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 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 5/026 Control of mixing and/or overlay of colours in general G09G5/022 and G09G5/024 take precedence
• CPC Class Codes: H04N 9/64 Circuits for processing colour signals H04N9/77 takes precedence; camera processing pipelines for processing colour signals H04N23/84

Abstract

A system for maintaining a substantially constant display white point over an extended period of operation of a color display formed by an array of multiple pixels in which each of the pixels includes multiple subpixels having different colors, and each of the subpixels includes a light emissive device. The display is generated by energizing the subpixels of successively selected pixels, and the color of each selected pixel is controlled by the relatives levels of energization of the subpixels in the selected pixel. The degradation behavior of the subpixels in each pixel is determined, and the relative levels of energization of the subpixels in each pixel are adjusted to adjust the brightness shares of the subpixels to compensate for the degradation behavior of the subpixels. The brightness shares are preferably adjusted to maintain a substantially constant display white point.

Claims

1. A method of maintaining a substantially constant display white point over an extended period of operation of a color display formed by an array of multiple pixels, each of said pixels including multiple subpixels having different colors and each of said subpixels including a light emissive device, said method comprising

generating a display by energizing the subpixels of successively selected pixels,

controlling the color of each selected pixel by controlling the relatives levels of energization of the subpixels in the selected pixel,

determining the degradation behavior of the subpixels in each pixel, and

adjusting the relative levels of energization of the subpixels in each pixel to adjust the brightness shares of said subpixels to compensate for said degradation of said subpixels, said brightness shares being adjusted to maintain a substantially constant display white point.

2. The method of claim 1 in which said degradation behavior is a shift in the chromaticity coordinates of the subpixels of a selected pixel.

3. The method of claim 2 in which said selected pixel is a white pixel.

4. The method of claim 1 in which said light emissive device is an OLED.

5. The method of claim 1 in which said display is an RGBW display.

6. The method of claim 1 in which said extended period of operation is at least 75,000 hours.

7. The method of claim 1 in which said degradation behavior is detected by measuring the voltage across said light emissive device.

8. A method of maintaining a substantially constant display white point over an extended period of operation of a color OLED display formed by an array of multiple pixels, each of said pixels including red, green, blue and white subpixels, said method comprising

generating a display by energizing the subpixels of successively selected pixels,

controlling the color of each selected pixel by controlling the relatives levels of energization of the subpixels in the selected pixel,

determining the shift in the chromaticity coordinates of the subpixels in each pixel as said subpixels age, and

adjusting the relative levels of energization of the subpixels in each pixel to adjust the brightness shares of said subpixels to compensate for the shift in the chromaticity coordinates of said subpixels, said brightness shares being adjusted to maintain a substantially constant display white point.

9. A system for maintaining a substantially constant display white point over an extended period of operation of a color display, said system comprising

a color display formed by an array of multiple pixels, each of said pixels including multiple subpixels having different colors and each of said subpixels including a light emissive device,

drive circuitry for energizing the subpixels of successively selected pixels and controlling the color of each selected pixel by controlling the relatives levels of energization of the subpixels in the selected pixel, and

a controller monitoring the degradation behavior of the subpixels in each pixel and adjusting the relative levels of energization of the subpixels in each pixel to adjust the brightness shares of said subpixels to compensate for said degradation of said subpixels, said brightness shares being adjusted to maintain a substantially constant display white point.

10. The method of claim 9 in which said degradation behavior is a shift in the chromaticity coordinates of the subpixels of a selected pixel.

11. The method of claim 10 in which said selected pixel is a white pixel.

12. The method of claim 9 in which said light emissive device is an OLED.

13. The method of claim 9 in which said display is an RGBW display.

14. The method of claim 9 in which said extended period of operation is at least 75,000 hours.

15. The method of claim 9 in which said degradation behavior is detected by measuring the voltage across said light emissive device.