A screen that scans

Posted February 23, 2006

You know the old joke about the computer user complaining about how their new fax-modem is a piece of crap? "I hold the paper up to the screen and press 'send', and nothing happens!"

Well, Toshiba is working on making that a reality. They have a demonstrated prototype display which integrates a bunch of photosensors right among the LCD display elements, so the same screen can both produce an image as well as capture the image of anything pressed up against the screen, at the same resolution. They actually demoed this a couple of years ago, but it showed up again in a recent SID article, which is how it caught my eye now.

I'm a little skeptical of the details of this, since ordinarily an LCD has a layer of plastic or glass on top of it, which would seem to inhibit the ability to get a good pixel-accurate scan without some extra optics: each sensor would normally be covering some larger angle. But it's just a prototype, so maybe Toshiba left off the cover. You could also use some molded lenslet arrays without a lot of trouble to improve things.

Given that this is somewhat old news, I'm kind of disappointed that nothing has apparently come of the technology since then. I guess with the ubiquity of cheap digital camera chips, there isn't much demand for tech which does the same thing only with less flexibility. Still, it would be cool to have the option, especially for, say, a super graphics tablet/display. At a minimum you can use the same technique to emulate a touch-screen by detecting the shadow of a finger or stylus, and at higher resolution you can probably do a fingerprint scanner as well.