本文对一种LTPS-TFT AMOLED电压型阈值电压(Vth)补偿像素电路进行了理论研究, 分析了影响Vth补偿效果的主要因素。电路的补偿效果主要由驱动TFT Vth的获取精度和随后的保持精度决定。在Vth获取过程中, 相关误差主要由驱动TFT转移特性电流对存储电容充电的充电率不足产生; 在显示信号与Vth叠加过程中, 与Vth保持节点连接的电容增量等因素会造成Vth保持精度的损失。根据分析的结果, 本文解释了高分辨率像素电路补偿效果下降的原因。

This paper presents a LTPS-TFT voltage-programmed threshold voltage (Vth) compensation pixel circuit for AMOLED. Two effective factors on the compensation are studied and analyzed, one is Cst charging level in driving TFT Vth detecting and the other is keeping accuracy of detected Vth in display signal adding. In the process of Vth detecting, the correlated error is attributed to insufficient Cst charging through driving TFT’s transfer current; and in the subsequent process of display signal adding, the accuracy loss of Vth keeping is attributed to the increment of capacity connected to the Vth keeping node. According to the analyses, the reason of compensation decaying in the high resolution pixel circuit is explained.