An AMOLED Pixel Structure Using Poly-Si TFTs for Compensating Threshold Voltage and Mobility Variations

Abstract

In active matrix organic light emitting diode (AMOLED) displays, the image quality is mainly degraded due to variations in threshold voltage (Vth) and mobility (u) of the driving TFT which is fabricated on poly-crystalline silicon (poly-Si) backplane. To improve the image quatlity of the AMOLED displays, several compensation methods for variations in Vth and mobility have been researched. The Vth variation is compensated for every gray level by using a diode connection method, whereas the mobility variation is compensated for only a specific gray level. In this paper, we propose a pixel structure to compensate mobility variations for every gray level. The proposed pixel structure show that the emission current error is less than ��7% for every gray level when the mobility variation of TD is ��10%.