This paper presents a new poly-Si pixel circuit employing AC driving mode for active matrix organic light-emitting diode(AMOLED) displays.The proposed pixel circuit,which consists of one driving thin-film transistor(TFT),three switching TFTs,and one storage capacitor,can effectively compensate for the threshold voltage variation in poly-Si and the OLED degradation.As there is no light emission,except for during the emitting period,and a small number of devices used in the proposed pixel circuit,a high contrast ratio and a high pixel aperture ratio can be easily achieved.Simulation results by SMART-SPICE software show that the non-uniformity of the OLED current for the proposed pixel circuit is significantly decreased(< 10%) with an average value of 2.63%,while that of the conventional 2T1C is 103%.Thus the brightness uniformity of AMOLED displays can be improved by using the proposed pixel circuit.
