E-Paper Displays

4Fast‐Switching Mode with CLEARInk Structure

Robert J. Fleming PhD

CTO CLEARink Displays, San Jose, CA, USA

4.1 Introduction

Ideally, reflective displays offer the same features as traditional emissive displays but with lower power usage, excellent outdoor readability, better viewing angle performance, and a paper‐like experience that reduces eye strain. Researchers for decades have been developing reflective display technologies to meet as many of these features as possible. Reflective displays modulate the light that impacts the surface of the display from the surrounding environment. One way to broadly categorize reflective display technologies is through the optical mechanism by which the display returns the ambient light to the user. This classification leads to three general categories of reflective displays, diffuse reflective, specular reflective, and retroreflective (Figure 4.1).

White paper is a Lambertian or diffuse reflector, meaning light that impacts the paper's surface is reflected uniformly in all directions. E Ink's (E Ink Corporation/E Ink Holdings – Boston/Taiwan) electrophoretic display technology is also a diffuse reflector and can exhibit a paper‐like viewing experience (Figure 4.1a. In a clear fluid, the E Ink technology utilizes negatively charged white particles and positively charged black particles. [1]. The light is modulated by applying an electric field and preferentially moving either the white particles or the black particles to the surface to ...