Pixel structures using the negative feedback method for high-resolution active matrix organic light-emitting diode displays

Abstract

Novel two pixel structures are proposed for high-resolution active matrix organic light-emitting diode displays. The proposed two pixels (pixel structures A and B) use the negative feedback method for high-resolution displays that requires to have small-sized storage capacitance. The proposed pixel structures A and B improve the luminance uniformity by reducing the voltage distortion in the storage capacitor. However, the proposed pixel structure A is vulnerable to the organic light-emitting diode (OLED) degradation because the anode voltage of the OLED affects the emission current. In order to compensate the OLED degradation, the proposed pixel structure B stores the turn-on voltage of OLEDs in the storage capacitor. The simulation results show that the emission current error of the proposed pixel structure B is improved by four times in comparison with the proposed pixel structure A when the OLED turn-on voltage increases by 0.1 V. Also, the emission current error of the proposed pixel structure B when the threshold voltage of driving thin-film transistors varies from -2.2 to -1.8 V is from -0.69 least significant bit (LSB) to 0.13 LSB, which shows the excellent luminance uniformity. The proposed pixels are designed for 5.5-in. full high-definition displays.