2. Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong 510006, China
Overview:Electrowetting display is a new type of paper-like display, which has the characteristics of low power consumption, high contrast, no radiation and easy colorization, and is one of the most promising display technologies in the future. In order to play video in real time of electrowetting display, a display driving system which includes a DVI video codec system and FPGA timing control system is designed. The DVI system is responsible for acquiring the signal source, for performing image encoding and decoding, and for obtaining all kinds of various resolution videos. The video source comes from the computer, and is not required to be stored. The operation is simple and convenient. Dual-link DVI system supports to transfer ultra-high resolution video, and the system is suitable for electrowetting display panels with increasing resolution at later stages. FPGA is responsible for buffering and processing of video data and for controlling electrowetting driving waveforms. FPGA can easily process video image data of various resolutions due to its powerful and high-speed data parallel processing capability. The driving waveform for electrowetting is also controlled by FPGA without other waveform generator devices, which is more conducive to the development of the driving system into a portable device. In terms of driving waveform, the ordinary multi-gray electrowetting driving waveform can display the image of 9th gray scale, but the ink is prone to splitting under the driving voltage. The charge trapping phenomenon is serious. The ink-splitting phenomenon can decrease the aperture ratio and brightness of electrowetting display panels, and the charge-trapping phenomenon would increase the close response time of the ink and reduce the frame rate, which is not conductive to play video. This paper also proposes an improved multi-grayscales dynamic symmetrical driving waveform, which improves the ink-splitting phenomenon and suppresses the charge-trapping phenomenon while increasing the gray level. The results show that the driving system successfully improves the problems of oil-splitting and charge-trapping, and drives the 1024x768 resolution electrowetting display to play video in real time following the computer. The frame rate of the video reaches 60 frames/second, and the highest gray level of the pixel reaches 15. The video image has clear details, and the system transmission is stable. These properties meet the requirements for dynamic display of the electrowetting paper.