Fujitsu's second-gen color e-paper – brightness x 1.3, re-write speed x 2, contrast x 3
By Gizmag Team
May 9, 2010
E-paper has some compelling advantages for the next generation of handheld and tablet devices. It provides an image which is very stable and easy to read in comparison to commonly used screen technologies, it consumes negligible power and is lightweight and paper-thin. Color paper arrived in 2007 but it hasn't really been good enough, until now. The principal developer of color e-paper to date has been Fujitsu which has just announced a dramatic increase in color e-paper display quality. The technology will be shown this week at Fujitsu Forum 2010 (May 13 - 14 at Tokyo International Forum) and can be expected in Japanese market e-book readers and advertising billboards by Q3 this year.
Most e-paper applications to date - mainly e-book readers but also clocks, watches and information displays - have been monochrome (black and white). Fujitsu pioneered the development and practical use of color e-paper and introduced the world's first commercially-available color e-paper product in 2007 in the FLEPia portable information terminal, but the first generation was not good enough to develop market momentum. That looks likely to change later this year when Fujitsu Frontech begins commercializing the new e-paper.
The new color e-paper has extensively redesigned image re-write methods and panel structure and offers a reflectance of 33% (effectively 1.3 times brighter color), an improved contrast ratio of 7:1 (a threefold improvement compared to Fujitsu's previous version), an image re-write speed of 0.7 seconds (half the re-write time), smooth image transitions. This sets a new benchmark for color e-paper display quality according to Fujitsu.
The second generation color e-paper employs a layered construction found in cholesteric liquid-crystal display (LCD) panels with an image memory function, and makes use of the reflective properties in each color layer where the cholesteric liquid crystals reflect a specific wavelength of light of red, green, or blue. Compared to the reflective displays using a color-filter array widely used in conventional LCDs, Fujitsu's cholesteric LCD method allows for a display that features colors with greater vibrancy and brightness.
With a panel structure that suppresses excess reflection caused by the scattering of incident light when displaying black, the new color e-paper features a 7:1 contrast ratio - three times greater than Fujitsu's previous color e-paper.
A new driver control method results in re-write speeds that are roughly twice as fast the speeds of previous color e-paper, enabling the re-write display of a high-resolution image (1,024 x 768 XGA) in 0.7 seconds.