A Driving Waveform with a Narrow Falling and High-Voltage Reset Structure for Improving the Stability of Electrowetting Displays

Abstract

An electrowetting display (EWD) is a new reflective display device with the advantages of paper display, high reflectivity, and fast response times. However, the display performance of EWDs has been restricted by oil film splitting and luminance oscillation. Therefore, a new driving waveform based on a falling slope function and a high-voltage, square-wave reset signal is proposed to solve these defects. It consists of a shrinkage stage and a stabilizing stage. First, the oil film of a pixel can be quickly ruptured by applying a falling slope function during the shrinkage stage according to the oil film-splitting theory. Then, a direct current (DC) voltage is applied to promote the complete fusion of the dispersed oil films by analyzing the voltage characteristic curves of EWDs. Finally, a high-voltage, square-wave reset signal is applied during the stabilizing stage to reduce luminance oscillations and suppress oil film backflow. Experimental results show that the average luminance was increased by 6.5% compared with a PWM driving waveform. The display stability of EWDs was improved by 89.1% compared with a driving waveform with a rising gradient.