An electrophoretic display includes a cell having a viewed region and a non-viewed region. The cell contains a suspending fluid and a first particle species and a second particle species dispersed within the suspending fluid. Application of a first electrical field causes the first particle species and...http://www.google.com/patents/US20040119680?utm_source=gb-gplus-sharePatent US20040119680 - Switching of two-particle electrophoretic display media with a combination of AC and DC electric field for contrast enhancement
