Patent ID: 7701422

Claim:
Active matrix display device ( 6 ) comprising a display panel ( 2 ) with a matrix of display pixels ( 3 ), and row and column electrodes ( 11 , 12 ) coupled to said display pixels ( 3 ), each of said display pixels ( 3 ) having a current mirror circuit adapted to receive a programming current (I prog ) via said column electrodes ( 11 ) and to reproduce said programming current (I prog ) for driving an emissive element ( 14 ), wherein said display device ( 6 ) is further arranged to execute a calibration phase wherein a calibration voltage (V cal ) is applied at each column electrode ( 11 ) before said programming current (I prog ) is applied and said calibration voltage is substantially maintained at said column electrode ( 11 ) for each of said display pixels ( 3 ) until said programming current (I prog ) is applied, and wherein each of said display pixels ( 3 ) further comprises calibration circuitry having a capacitor (C cal ) and a transistor (T cal ) whose current carrying electrodes are connected between said column electrode ( 11 ) and a first plate of said capacitor (C cal ), and is arranged to charge said capacitor (C cal ) prior to said calibration phase and to discharge during said calibration phase via said transistor (T cal ) such that the gate of said transistor (T cal ) carries a voltage substantially equal to the sum of said calibration voltage (V cal ) and a threshold voltage (Vt) of said transistor (T cal ).