Pixel Circuit With Parallel Driving Scheme for Compensating Luminance Variation Based on a-IGZO TFT for AMOLED Displays

Abstract

This work proposes a new pixel structure based on amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) and a parallel addressing scheme for high-resolution active-matrix organic light-emitting diode (AMOLED) displays. The proposed circuit compensates for the nonuniformity of luminance that is caused by shifts in the threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> ) and mobility of driving TFTs. Measurement results verify that the parallel addressing scheme successfully extends the compensation time and accurately detects the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> of the driving TFT. Moreover, the proposed circuit reduces the variations of OLED luminance from more than 83% to less than 13% when the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> and mobility of driving TFT shifts by 1 V and 30%, respectively, and the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> of OLED varies from 0 to 0.9 V.