| 摘要 |
A method of driving an active matrix display device comprises, for each pixel, driving a current through a drive transistor (22) by applying a gate voltage to the drive transistor which comprises a fixed component and a component which depends on a measurement of the threshold voltage of the drive transistor (22), and switching off the drive transistor using a discharge transistor (36) for discharging a capacitance between the gate and source of the drive transistor (22), and at a time which depends on the optical output of the display element (2) and a pixel data signal. This method uses optical feedback to implement a duty cycle control for the output of the display element. The brightness of the display element when turned on is determined by the drive transistor drive voltage, and this takes account of the threshold voltage. Although the optical feedback system enables compensation of the threshold voltage, by providing compensation initially in this way, the lifetime for correct functioning of the optical feedback system can be extended. The time at which the drive transistor is switched off can also depend on a measured threshold voltage of the discharge transistor.
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