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DIY Electronic Paper Display
An anonymous reader writes "LinuxDevices.com has an article about a development kit for prototyping device displays based on electronic paper technology. The kit includes a 170dpi, 6-inch (diagonal) SVGA (800 x 600) EPD (electronic paper display) module supporting four shades of gray, and a small computer module that runs the display. EPDs provide bright, high-contrast, thin, lightweight displays that remain legible under 'any lighting condition' -- much like newsprint. Once an image has been 'printed,' no power is needed to hold it."
I don't know about anyone else, but I've been looking for a dev kit like this forever. Even just as an E-Reader (what the dev kit is preconfigured for) the possibilities are tremendous!
I'm a bit annoyed that it's taken 30 years since Xerox first developed the idea, but at least it's here now. Just imagine if this technology catches on. No more need for paperback books (you can keep all the latest on your pocket reader), technical books can finally be portable now that page graphics can be shown in detail, and eye strain will reduce considerably as your eyes can lock onto something that's actually there rather than simulated by a beam of light.
Javascript + Nintendo DSi = DSiCade
To expand:
1. Hi-Res Palm Pilots are 300x300 whereas this first-gen dev kit is 800x600.
2. In theory, eInk has all the contrast of paper. In practice it often has a slightly grey background, but still plenty of contrast in comparison to computer screens.
3. This effectively means that the processor can be put in a wait state or possibly turned off when the screen isn't being updated. For ebook readers, watches, and personal organizers, there's even the possibility of using something REALLY low power like a PIC since you're only updating the screen on very rare occasions.
Javascript + Nintendo DSi = DSiCade
I have used the LibriE electronic book mentioned in the article, which is available in Japan. I felt that it was an adequate replacement for a book, with an easily readable screen. Changing the page had some delay, but on the other hand so does changing the page of a real book. I imagine that the target audience of this are people wishing to read books on crowded Tokyo trains. Since less space is required this could be a good book replacement, after the cost comes down a bit. Biggest problem for their target group surely must be reading newspapers on the train, since they require a lot of space to open. It would be nice to see them provide newspapers for easy download to these devices.
I've seen figures of around 0.5-1.0 seconds per pixel full addressing for these type of displays. :)
o ws_electronic_paper_potential_052301.html
Whilst not quick enough for movies (as you point out), would be perfectly acceptable for virtual paper
heres a link to an article mentioning the 1second refresh
http://www.trnmag.com/Stories/052301/Prototype_sh
"In addition, although the transistors allow a switching speed of about 2.5 milliseconds, the total time for an image to change smoothly is about one second; typical LCD's pixels are refreshed 70 times a second. "Currently the electronic ink, and not the transistors, limit the speed,"
liqbase
Sigh.
Quoted "constrast ratio" for active screens is not the same as the actual viewed contrast ratio of the LCD. That's the contrast ratio of the emitted white sections over the emitted black sections. But that's not what the eye sees, because it sees "emitted+reflected". The true contrast ratio of an active LCD varies with lighting conditions. It can be very very high in dark rooms (100:1, 500:1, etc.), but will be very very low in any sort of lit room. Outside, it'll probably be near 1:1 - i.e., unviewable. Much lower than that 100:1, 500:1. More like 4:1, or lower, in normal viewing conditions.
The contrast ratio of an E-ink display is about 10:1. Moreover, the E-ink display has about a 40% reflectance (as opposed to a 4% reflectance for LCDs), which means it's much brighter too.
CRTs have the same problem. They quote a 3000:1 contrast ratio, but the black and white sections have virtually the same reflectivity, which means that that contrast ratio only applies when the light in the room is much less than the light emitted from the CRT.
If you want to compare passive and active displays, you have to do it equally. In the same viewing conditions. Most people I know don't work inside pitch black offices.
and simple lambertian demands limit the reflectivity of the white areas (its no mirror, you know?)
E-ink displays are slightly less white state reflective than newsprint, but not much (40% compared to 60%). They have a much, much higher reflectivity than LCD displays - about 10 times higher (LCDs are 4%). With that high reflectivity, it doesn't take a lot of light for an E-ink display to have a much higher contrast ratio than an active LCD.