Improvement of aperture ratio and grayscale stability of electrowetting displays by designing a combined driving waveform of an exponential function and AC voltage

Abstract

Electrowetting display (EWD) is a promising new type of reflective displays. In order to improve its performance, a new driving waveform based on an exponential function and an alternating current (AC) square wave was proposed in this paper. It consisted of an oil shrinking stage and an oil stabilizing stage. The design process is as follows: First, the threshold voltage and maximum driving voltage of an EWD were determined by testing the relationship between direct current (DC) voltages and luminance values. Second, an exponential function voltage sequence was designed to suppress oil splitting, it was increased from the threshold voltage. Thereby increasing the aperture ratio. Experimental results showed that phenomena of oil splitting and backflow could be avoided. In addition, the luminance value of an EWD was increased by 16.2% compared with a traditional exponential function waveform, and the response time was reduced by 27.3% compared with a slope function waveform.