E-Paper Displays

2Fundamental Mechanisms of Electrophoretic Displays

Bo‐Ru Yang¹ and Kristiaan Neyts²

¹ Professor, School of Electronics and Information Technology, State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat‐Sen University, Guangzhou, China

² Professor, and Head of Liquid Crystals and Photonics group, ELIS Department, Ghent University, Technologiepark 126, B‐9052 Ghent, Belgium

2.1 General View of Electronic Ink Operation

Electronic ink contains pigment particles, charge controlling agents (CCAs), non‐polar solvents, and various additives. The particles are charged by the CCAs to be transported in the solvent by an electric field. The interaction between these ingredients in ink is complicated. Therefore, to explain the whole operation in a more easily understandable way, we will start from the general concepts of the driving waveform, the charging mechanism of inverse micelles (IMs), the drift and diffusion of inverse micelles, the charging of particles with additives, the rheological behavior of charged particles, and then the driving method for realizing full‐color e‐paper.

The driving voltage waveform, which updates an electronic ink display, typically includes several stages [1]. The particles' track during the update process is illustrated in Figure 2.1a for a pixel with top and bottom electrodes. In a typical driving waveform, particles are first agitated by an alternating voltage (“shaking ...