External compensation for high-resolution active matrix organic light-emitting diode displays

Abstract

Two different external compensation methods for high-resolution active matrix organic light-emitting diode (AMOLED) displays are presented and compared. Both compensation methods are implemented using a small pixel circuit, namely, a 3T2C and a 2T1C pixel circuit, allowing high-resolution displays. Due to the simple driving schemes, these methods allow fast driving, even for large displays. The characterization results show a significant improvement in current variation by implementing either of these methods. The V-T compensation method using a 3T2C pixel circuit is able to reduce the current variation down to 0.56%, whereas the V-T- and beta-factor compensation method using a 2T1C pixel circuit demonstrates a further reduction in current variations down to 0.079%. This method also clearly shows significant improvement in optical variation between neighboring pixels.