Yesterday
we heard that color e-paper based on E Ink wouldn't be ready for prime time this year (perhaps next year, but who knows?). It was stated by the chairman of PVI that there were still "barriers to achieving satisfying results." What kind of barriers? Coincidentally, the Technology Review
runs an article on their website today with the following relevant information:
- Color displays normally require four subpixels--red, green, blue, and white--to create each full-color pixel. "That costs you in terms of resolution," says Pieter van Lieshout, head of product research and development for Polymer Vision [creator of the Readius].
- The other consequence of using a color filter is that it reduces the brightness of a display, says Sri Peruvemba, vice president of marketing at E-Ink.
So, with existing technologies,
take away resolution and brightness - two of the main selling points of e-paper technology - and you get color. Not a very satisfying equation.
The article mentions Philips Research, who is working on a better solution, referred to as in-plane electrophoretics (IP-EPD), where the display is changed by electrically controlling the in-plane distribution of the pigment particles on the foundation.
Quote:
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By carefully controlling the voltages at electrodes positioned on the edges of the pixels, it is possible to spread the colored particles across the pixel or remove them from view altogether by hiding them behind the electrodes, says Lenssen. This means that different shades of color can be achieved by controlling how many of each group of colored particles are visible. To create white, all of the particles are simply shifted to the side to reveal the white substrate beneath the two microcapsules.
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Unfortunately, both Mr. van Lieshout from Polymer Vision and Peruvemba from E Ink believe that this technology is still too early to be used for first generation E Ink color displays. They also argue that color filters (with all their disadvantages, see above) are easier and cheaper to produce.
This all means that it will be very interesting to see how well the first commercial color e-paper will perform compared to their grey ancestors.
