Tokyo, Japan--An electrophoretic display exhibited by Fuji Xerox at this month’s Society for Information Display (SID) 2012 conference (Boston, MA) may be a forerunner of the long-hoped for passive color display that is bright, colorful, and easy to read (rather than murky and grayish, like many of today’s prototypes).
If true, then prospects for a usable color e-reader have also just brightened. The e-paper display achieves its relatively bright colors because it does not rely on color filters, but instead produces colors intrinsically by moving colored particles for each color. To control each particle color, Fuji Xerox created a design in which the threshold electric field for electrophoretic particle movement is different for each particle color.
In addition to the colored particles, white particles are placed between the front and back display substrates; the white particles do not move even when an electric field is generated between the substrates. as a result, white is displayed by drawing all the colored particles to the back substrate.
The SID prototype has a 5 in. screen size and only two types of colored particles: red and cyan. The device has a pixel count of 600 x 800, a resolution of 200 dpi, a gradation of four levels, a reflectance of 30%, and a contrast ratio of 10:1. It uses amorphous silicon (Si) TFTs for the back substrate.
Though the prototype uses only two colors, Fuji Xerox is currently developing a full-color e-paper using three elementary colors (cyan, magenta, and yellow). The company says the three-color version has a color gamut wider than that of newspaper.
Source: http://techon.nikkeibp.co.jp/english/NEWS_EN/20120608/222034/
