P‐101: Current Driving Pixel Circuities for Active Matrix Organic Light Emitting Diode Display

Abstract

A modified multi‐transistors pixel circuit for active‐matrix organic light‐emitting displays (AMOLED) was developed to improve the linearity of input and drain current in low‐brightness or low gray‐scale region by supplying an additional programmable bias voltage. This modified multi‐transistor pixel circuit is suitable for driving high efficient OLED as the drain current is getting smaller compared to the conventional OLED at the same brightness. The optimal values of the programmable bias voltage as well as the characteristics of the pixel circuit were investigated using Smart‐SPICE. The simulated data reveal that the deviation of drain current can be improved by supplying a low bias voltage to drive the TFT in low gray‐scale region. In addition, this multi‐transistor pixel circuit is also capable of compensating the non‐uniformity caused by the variations of low‐temperature poly‐silicon thin‐film transistor's (LTPS‐TFT) characteristics.