Advancement of Flexible Electrophoretic Displays
An electrophoretic display (EPD) consists of an electrophoretic front plane laminate (FPL), and a TFT backplane. The FPL, which is manufactured in a roll-to-roll process for mass production, is intrinsically flexible. As long as the TFT backplane adopts a flexible substrate material such as PI, PEN, PET, etc., the entire EPD stack can be flexible. Therefore the electrophoretic displays are ideally suited for flexible applications. Flexible EPD has the advantage of lightweight, as well as being conformable, bendable, rollable and foldable. Combining the characteristics of Lambertion reflectivity, sun-light readability and bistability, the electrophoretic displays look like paper, read like paper, and write like paper. On the other hand, a flexible EPD has the advantage of lightweight, as well as the potential of being conformable, bendable, foldable and rollable. The coupling of the two opened up a wide range of new applications ranging from small wearable devices such as watches, smart cards, e-readers, e-notes, tablets, music scores, all the way to large interactive board, digital signage or architectural applications. In recent years there have been several companies trying to commercialize flexible EPD for end devices by utilizing several flexible TFT backplane technologies. One such example is the A4-sized digital paper device launched by Sony in 2014, with lightweight (360 grams) and pen input. Since then there has been a wider range of applications of the flexible EPD. Recently, with the debut of foldable mobile phones in the consumer market, there has been much interest in the market for flexible devices. This presentation will cover a range of flexible EPD applications, as well as the development of different flexible TFT backplane technology including organic TFT for flexible EPD. The migration of screen size from small to large, and the evolution of form factor from flat tablet to formable, foldable, or rollable are two primary directions for the development of the flexible TFT backplanes for electrophoretic display. The flexible electrophoretic displays open up opportunity for new product categories and market opportunity for both consumer and commercial applications.