Method and system for programming, calibrating and/or compensating, and driving an LED display

• US 10,699,624 B2
• Filed: 06/11/2018
• Issued: 06/30/2020
• Est. Priority Date: 12/15/2004
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza, Alexander, Stefan, Servati, Peyman, Huang, Richard I-Heng, Church, Corbin
• Primary Examiner(s): Regn, Mark W
• Application Number:
  US16/005,177
• Publication Number:
  US 20180301077A1
• Time in Patent Office: 750 Days
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• 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
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A method and system for programming, calibrating and driving a light emitting device display, and for operating a display at a constant luminance even as some of the pixels in the display are degraded over time. The system may include extracting a time dependent parameter of a pixel for calibration. Each pixel in the display is configured to emit light when a voltage is supplied to the pixel'"'"'s driving circuit, which causes a current to flow through a light emitting element. Degraded pixels are compensated by supplying their respective driving circuits with greater voltages. The display data is scaled by a compression factor less than one to reserve some voltage levels for compensating degraded pixels. As pixels become more degraded, and require additional compensation, the compression factor is decreased to reserve additional voltage levels for use in compensation.

Claims

1. A method of adjusting the operating conditions for pixels in an OLED display to compensate for non-uniformity or aging of the display, said method comprising

setting one or more initial operating condition values,

calculating compensation values for the pixels in the display,

determining the number of pixels having compensation values larger than a predetermined threshold compensation value, and

if the determined number of pixels having compensation values larger than said predetermined threshold value is greater than a predetermined threshold number, adjusting the set one or more initial operating condition values until said determined number of pixels is less than said predetermined threshold number.

2. The method of claim 1 in which said initial operating value is set by an application or algorithm controlling the power, temperature or other display factor.

3. The method of claim 1 in which said compensation values are at least one of pixel drive data, pixel luminance data, and pixel current data.

4. The method of claim 1 in which said predetermined threshold compensation value is based on at least one of maximum compensation headroom available and aging acceleration factors.

5. The method of claim 1 in which said predetermined threshold number is the maximum tolerable number of pixels having wrong compensation levels.

6. The method of claim 1 in which said compensation values are based on compensating for at least one of non-uniformity of the display, aging, temperature and other display performance factors.

7. The method of claim 1 in which said reducing is effected periodically, in response to a predetermined event, or in response to a user-initiated request.

8. The method of claim 1 in which said one or more initial operating condition values include a peak luminance programming value.

9. A display degradation compensation system for adjusting the operating conditions for pixels in an OLED display to compensate for non-uniformity or aging of the display, said system comprising a controller programmed to

set one or more initial operating condition values,

calculate compensation values for the pixels in the display,

determine the number of pixels having compensation values larger than a predetermined threshold compensation value, and

if the determined number of pixels having compensation values larger than said predetermined threshold value is greater than a predetermined threshold number, adjust the set one or more initial operating condition values until said determined number of pixels is less than said predetermined threshold number.

10. The system of claim 9 in which said initial operating value is set by an application or algorithm controlling the power, temperature or other display factor.

11. The system of claim 10 in which said compensation values are based on compensating for at least one of non-uniformity of the display, aging, temperature and other display performance factors.

12. The system of claim 9 in which said compensation values are at least one of pixel drive data, pixel luminance data, and pixel current data.

13. The system of claim 12 in which said reducing is effected periodically, in response to a predetermined event, or in response to a user-initiated request.

14. The system of claim 12 in which said one or more initial operating condition values include a peak luminance programming value.

15. The system of claim 9 in which said predetermined threshold compensation value is based on at least one of maximum compensation headroom available and aging acceleration factors.

16. The system of claim 9 in which said predetermined threshold number is the maximum tolerable number of pixels having wrong compensation levels.