Method and system for programming, calibrating and/or compensating, and driving an LED display
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.
1. A method of adjusting operating conditions for pixels in an OLED display, said method comprising
calculating pixel values for a plurality of pixels in the display,
determining the number of pixels having pixel values satisfying threshold criteria, and
if the determined number of pixels is greater than a predetermined threshold number, adjusting an operating condition for the pixels in the display until said determined number of pixels is less than said predetermined threshold number.
2. The method of claim 1 further comprising, prior to calculating pixel values, setting the operating condition by an application or algorithm controlling the power, temperature or other display factor.
3. The method of claim 1 in which said pixel values are at least one of compensation data, pixel drive data, pixel luminance data, and pixel current data.
4. The method of claim 1 in which said threshold criteria 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 pixel levels.
6. The method of claim 1 in which said pixel values include compensation values 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 adjusting 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 operating condition includes a peak luminance programming value.
9. A display degradation compensation system for adjusting operating conditions for pixels in an OLED display, said system comprising a controller programmed to
calculate pixel values for a plurality of pixels in the display,
determine the number of pixels having pixel values satisfying threshold criteria, and
if the determined number of pixels is greater than a predetermined threshold number, adjust the an operating condition for the pixels in the display until said determined number of pixels is less than said predetermined threshold number.
10. The system of claim 9 in which the controller is programmed further to, prior to calculating pixel values, setting the operating condition by an application or algorithm controlling the power, temperature or other display factor.
11. The system of claim 10 in which said pixel values include compensation values 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 pixel values are at least one of compensation data, pixel drive data, pixel luminance data, and pixel current data.
13. The system of claim 12 in which said adjusting 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 operating condition includes a peak luminance programming value.
15. The system of claim 9 in which said threshold criteria 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 pixel levels.