It’s easy to track the development of e-paper simply by looking at the different generations of Amazon’s Kindle e-reader. The displays have got progressively better to the point where they even ship with the option of a backlight.
However, one area that still needs a lot of development is color. Producing color e-paper continues to be a problem, and we’ve yet to see a commercially viable solution that has been selected for use in a popular e-reading device. When a new Kindle ships with color e-paper, we know it’s viable.
Ricoh hopes to change that with the development of a new color e-paper display that has a unique new structure. The display is transparent, but uses an electrochromic material that can change color from cyan, to magenta, to yellow.
Electrochromism allows certain materials to change color when an electric charge is applied to them. This is a great solution for color e-paper as the charge is only required to change the color, not maintain it, meaning power use is very low. Ricoh also kept the thickness and complexity of the display to a minimum by making the required electrodes active TFTs, meaning you only need one electrode driver for the display, rather than one for each color layer used.
The prototype color e-paper Ricoh has on been showing off is 3.5-inches, 113.6ppi, and achieves 35 percent color reproduction. Importantly, that’s already higher than what is achieved for color in newspapers, plus Ricoh’s display has more than twice as bright as other color e-paper displays.
Ricoh is set to continue developing its display technology and wants to increase the size of the color e-paper to 6 and then 10 inches. The company also believes it can reduce screen refresh time down to 100ms, where as it currently takes over a second on the prototype.
We’ve seen better color e-paper from the likes of Fujitsu and its FLEPia display, but Ricoh’s solution looks to require much less power. Competition is also coming from Project Vivit Co. Ltd, which demonstrated the first video-capable color e-paper late last year.