Patent ID: 8373628

Claim:
An active matrix display device comprising an array of display pixels, each pixel comprising: a current-driven light emitting display element; a drive transistor for driving a current through the display element; pixel circuitry including an optical feedback element, for controlling the drive transistor to drive a substantially constant current through the display element for a duration which depends on a desired display pixel output level and an optical feedback signal of the optical feedback element; and control means for varying an output configuration for the display by varying the pixel power supply voltage and at least one of the field period and the allowed range of pixel drive levels in response to monitoring the ageing of the display element, wherein monitoring of the display element comprises monitoring the on or off state of the drive transistors at the beginning or end of a field period, wherein dedicated power supply lines are applied corresponding columns of different colour pixels, each different single dedicated power supply line being adjustable to suit the voltage operation of each colour.