A Multi Waveform Adaptive Driving Scheme for Reducing Hysteresis Effect of Electrowetting Displays

Abstract

Electrowetting display (EWD) is a new reflective display technology, which has the advantages of ultra-low power consumption, high contrast, fast response and full-color. However, due to a hysteresis effect, accurate gray scale display of EWDs cannot be achieved, which seriously restricted the display effect and performance of EWDs. In order to reduce the influence of hysteresis effect, a multi waveform adaptive driving scheme was proposed in this paper. Firstly, a multi waveform driving system was designed and implemented by a STM32 master chip and an AD5304 driver chip. The driving system could automatically select different driving waveforms according to the preset switching conditions. Then, different driving waveforms were designed and implemented according to different driving stages of EWDs. Finally, driving waveforms were mapped with each stage of the driving process one by one to realize the adaptive driving of multiple waveforms. The experimental results showed that, compared with the conventional square wave, the maximum hysteresis difference of hysteresis curve could be reduced by 39.19% with the multi waveform driving scheme.

Toward Suppressing Oil Backflow Based on a Combined Driving Waveform for Electrowetting Displays

“…Therefore, the grayscale display can be controlled by adjusting the driving voltage on ITO electrodes. In addition, the aperture ratio is defined as the area ratio between the glass substrate exposed after oil shrinking and the whole pixel grid, which is one of the important parameters for characterizing the performance of EWDs, the expression is shown in Equation (1) [4].…”

“…In 2003, an electrowetting display (EWD) based on the principle of electrowetting was proposed by Hayes [3]. Different driving voltages were used to control the movement of oil, which could achieve an optical display effect of color switching between oil and substrate [4]. As a new type of reflective display, EWDs effectively compensated for the shortcomings of traditional electronic papers in video playback and full-color display [5][6][7][8][9].…”

Review of Driving Waveform for Electrowetting Displays

“…The contact angle hysteresis can be reduced by optimizing driving waveforms. A multi-waveform adaptive driving scheme was proposed [53]. In this scheme, the contact angle hysteresis curves of EWDs driven by a square wave, a sine wave and a triangle wave were tested.…”

A Driving Method for Reducing Oil Film Splitting in Electrowetting Displays

“…Pixels of EWDs are fabricated using microtechnology. A pixel of EWDs is mainly composed of transparent glass, indium tin oxide (ITO) electrodes, pixel walls, conductive liquid (NaCl solution), color oil, and a hydrophobic insulating layer (fluoropolymer) [30][31][32], as shown in Figure 1. The color oil sticks to the hydrophobic insulating layer and forms a thin film when no voltage is applied.…”