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E Ink Creates Full-Color Electronic Paper Display (mashable.com)
SkinnyGuy writes: The reflective display company finally figured out how to make those ultra tiny balls produce 32,000 colors in one super-low-powered display. It's a breakthrough for E Ink, display advertising and, maybe someday, e-readers and digital photo frames. The new prototype display, which can be manufactured in an array of sizes, features a 20-inch, 2500 x 1600 resolution and is equally as power-efficient as the monochromatic display. E Ink Holding's Head of Global marketing Giovanni Mancini said it can be powered with solar cells used in bus stop signage, for example. Some of the limitations center around the resolution and refresh rate. As of right now, the resolution is only 150 pixels per inch (ppi), which is about half the resolution of a typical 6-inch, monochromatic E ink display. It also takes about two seconds to fully resolve images, which is pretty slow when compared to today's e-readers. The company is currently only focused on using the new color display for commercial signage.
I may be a little addled in my ability to remember, but I have this deeply nagging feeling at the back of my mind that they had a full color e-ink prototype waaaaaaaaaaaay back in the late 90s that used a super hydrophobic cell layer with electrically conductive partition walls.
IIRC, the paper was made from 4 transparent layers over a white back layer. Each layer held a CMYK pigment component in the form of an aqueus solution, held into a tight microdot form by superhydrophobic coatings inside each cell. When the cell is energized, hydroelectrodynamic forces cause the droplet to spread out and cover the cell, with the applied voltage to the cell determining how fully the droplet flattens and covers the cell.
That was waaaaaaaaaaay back though. I will dig to see if I can find the old press releases.