一种LTPS-TFT AMOLED像素电路的理论研究

本文对一种LTPS-TFT AMOLED电压型阈值电压(V_(th))补偿像素电路进行了理论研究,分析了影响V_(th)补偿效果的主要因素。电路的补偿效果主要由驱动TFTV_(th)的获取精度和随后的保持精度决定。在V_(th)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V_(th)叠加过程中,与V_(th)保持节点连接的电容增量等因素会造成V_(th)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。

LTPS-TFT threshold voltage compensation pixel circuit for AMOLED

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