ACTIVE MATRIX DISPLAY DEVICES WITH MODELLING CIRCUIT LOCATED OUTSIDE THE DISPLAY AREA FOR COMPENSATING THRESHOLD VARIATIONS OF THE PIXEL DRIVE TRANSISTOR

摘要

An active matrix display device having current-driven light emitting display pixels uses a modelling circuit outside the display area for modelling the behaviour of a plurality of the display pixels. The modelling circuit is provided with a pixel drive signal derived from the pixel drive signals for the plurality of display pixels. A transistor characteristic of the drive transistor in the modelling circuit is measured and the pixel drive signals for the plurality of display pixels are modified in response to the measured transistor characteristic. This can be used to provide an average correction for threshold voltage drift, and can thereby enable the use of amorphous silicon drive transistors whilst maintaining a simple pixel circuit.