Design of Multi-DC Overdriving Waveform of Electrowetting Displays for Gray Scale Consistency

Gray scale consistency in pixels was extremely important for electrowetting displays (EWDs). However, traditional electrowetting display driving waveforms could not obtain a pixel aperture ratio consistency, which led to the occurrence of gray inconsistency even if it was the same driving waveform. In addition, the oil backflow caused by charge trapping could not be sustained. Therefore, a multi-direct current (DC) overdriving waveform for gray scale consistency was proposed in this paper, which could effectively improve the performance of EWDs. The driving waveform was divided into a start-up driving phase and a stable driving phase. The stable driving phase was composed of a square wave with a duty cycle of 79% and a frequency of 43 Hz. Subsequently, an overdriving pulse was also introduced in the stable driving phase. The multi-DC driving waveform for gray scale consistency was applied to a thin film transistor-electrowetting display (TFT-EWD). The average difference between increasing driving voltage and decreasing driving voltage was only 2.79%. The proposed driving waveform has an aperture ratio of 3.7 times at low voltages compared to DC driving.

Automated summary

Gray scale consistency in electrowetting displays (EWDs) is crucial, but traditional driving waveforms fail to achieve pixel aperture ratio consistency and lead to gray inconsistency. This paper proposes a multi-direct current (DC) overdriving waveform to ensure gray scale consistency and enhance EWD performance. The waveform consists of a start-up driving phase and a stable driving phase, with a square wave of 79% duty cycle and 43 Hz frequency in the stable phase, supplemented by an overdriving pulse. Applied to a TFT-EWD, this waveform results in an average difference of only 2.79% between increasing and decreasing driving voltages, and achieves 3.7 times aperture ratio at low voltages compared to DC driving.