Fuji Xerox developed a new technology that enables color electrophoretic e-paper displays without using color filters. They call the new technology Independently Movalbe Color Particles (IMCP), and the idea is to use colored (Cyan, Magenta and Yellow) particle that each have a different electrophoresis threshold. Only the particles that are drawn to the front substrate can be seen. There are also white particles in between (they do not move) and so white can be displayed.
Fuji Xerox says that the new displays are brighter and have more vivid colors compared to color-filtered e-paper displays (such as E Ink's Triton panels). They have shown a 5" 600x800 (220 ppi) prototype featuring a contrast ratio of 10:1. The backplane is a-Si.