A New AMOLED Pixel Circuit With Pulsed Drive and Reverse Bias to Alleviate OLED Degradation

Abstract

This paper proposes a new pixel circuit for an active matrix organic light-emitting diode (OLED) display, which consists of five thin-film transistors (TFTs) and one capacitor. This circuit develops techniques of pulsed drive and reverse bias to achieve desired emitted brightness levels and elongate OLED life times, respectively. A current mirror is also adopted in the circuit to minimize emission nonuniformity of the OLED panel. The required input data voltages for varied displayed gray levels are calculated based on analytically known TFT and OLED models and the designed circuit architecture. The designed pixel circuit is simulated with realistic TFT models for validating expected performance to realize 256 gray levels and minimizing nonuniformity. The designed circuit is implemented in a 2.4-in quarter video graphics array panel, which shows favorable performance for minimizing display nonuniformity and alleviating OLED degradation. In addition, a closeness is clearly observed among analytical predictions, simulations, and experimental measurements.