抑制電泳式電子紙之殘影現象之驅動波形

Abstract

為了解決影響電泳式電子紙顯示器顯示品質之主要現象之一：殘影現象，一般常見的解決手法是使用快速切換黑白狀態的驅動波形來清除造成殘影現象的內部殘餘電場，但此種驅動波形不但費時且在黑白快速切換的過程中造成的閃爍會造成人眼的不舒適，因此本論文的設計目標是針對該閃爍驅動波形的缺點進行改善。 透過了解電泳式電子紙對於輸入不同電壓、不同形狀以及不同長度的驅動電壓的光學響應來了解電泳式電子紙之特性，並與已建立之電泳物理模型連結，以設計出更快速、更具抑制殘影能力並同時減少閃爍的驅動波形。 在最後應用於硬體的實作當中，對新設計之波形的各項表現與原本傳統之閃爍驅動波形比較。結果顯示新設計的波形不僅擁有更加優秀的殘影抑制能力，同時驅動時間只有閃爍波形的1/2，且最重要的是減少了閃爍波形中的閃爍所帶來的人眼不舒適，因此此新設計之波形有相當大的潛力能夠取代現有閃爍波形提供電泳式顯示器更加優良的顯示品質。

One of the main issues in electrophoretic displays (EPDs) is ghost image, also named ghosting. To suppress ghosting, the most common way is to apply shaking driving waveform with quickly changing polarity of electric field to neutralize the internal electric field which is considered as the cause of ghosting inside EPDs. However, the shaking driving waveform not only requires long driving time, but also makes the device flicker to discomfort human eyes. Therefore, our target is to design a new driving waveform with shorter driving, less ghosting, and with invisible flickers. Before we design the new driving waveform, the characteristics of EPDs have been studied by observing optical responses to input driving pulses with different voltages different waveform shapes, and with different pulse widths. Then, according to the results and the physical model based on electrophoresis, we design the new two-phased weakly-indirect transition driving waveform and compare its performance with the conventional shaking driving waveform. Finally, the experimental results show that our proposed new driving waveform not only improved ghosting by 26~37%, reduces driving time by 42~52%, but also comes with more invisible flickers. Thus, the proposed new driving waveform shows great potential to replace the conventional shaking driving waveform, and become the next driving waveform to display high quality images on EPDs.