NTT DoCoMo Inc. exhibited a mobile phone that uses electronic paper to display its keys at CEATEC Japan 2007 in a reference presentation. The e-paper was manufactured by SiPix Imaging Inc. It has a structure in which small chambers called Microcups filled with white particles and a colored liquid are formed on a plastic substrate. The e-paper thus allows the presentation of two colors, i.e., white using the white particles and another color using the dyed liquid. At present, SiPix Imaging is reportedly able to provide five types of two-color e-paper using blue, red, green, yellow and black liquids. NTT DoCoMo prototyped five models in colors that correspond to the five colors displayed on the e-paper.
NTT DoCoMo aims to increase the types of letters and characters that can be displayed to more than three and reduce the time required to redraw the display to about half a second.