iPhone-Style Touch on a Giant Screen
The touch-sensing technology used in gadgets like the iPhone and iPad could soon be seen in screens several meters across but only a few inches deep. Perceptive Pixel, based in New York, released a touch screen today with a diagonal dimension of 82 inches—just under seven feet—but only six inches thick.
“All of the [tablet] and phone manufacturers have settled on projected capacitance as the best way to do multitouch, but it has been really difficult to scale up,” says Jeff Han, founder of Perceptive Pixel. Projected capacitance involves sensing fingers when they distort the electric field around a transparent layer of electrodes across the surface of a screen. Scaling that up to much larger screens is challenging, because noise from the electronics in a display muddy the signal from a user’s touches.
Perceptive Pixel already makes large touch panels; some are used by broadcasters, including CNN, to display data such as weather forecasts or election results. But today these screens are relatively bulky—up to a meter deep. They sense touches using a technique known as frustrated internal reflection. It involves shining infrared light sideways through the glass surface of a display and using a camera behind the screen to track how fingers change the light’s path. The camera behind the screen needs to be a certain distance away in order to capture every touch. Perceptive Pixel has sold most of its displays to federal and defense customers that are willing to design or build rooms around the space required for such large displays.
Now the company has found a way to make projected capacitance work in much larger screens. “We developed algorithms for signal processing that can filter out that noise so you can detect the really small changes in capacitance needed to do multitouch,” says Han. “We can finally bring projected capacitance to the full-size range.” Earlier this year, Han announced a 27-inch screen that made use of this technology; improvements to the technique enabled the new 82-inch panel.
Han says this will allow much larger touch displays to appear in many more places. “This makes it possible for normal companies to use large multitouch displays for everyday work,” he says. “They are thin enough to install in any boardroom.”
Han expects to see his displays used by architects collaborating interactively on design ideas, or for videoconferencing where people on opposites sides of the country can use touch panels like a white board for long distance brainstorming. “This is really a communication device,” says Han.
Perceptive Pixel has also developed software than can be used to manipulate data on its screen in certain common formats. It is also working with large software companies to develop plug-ins so that their products can be used on large multitouch displays.
Jennifer Colegrove, an analyst specializing in emerging display technology at DisplaySearch, says that scaling projected capacitance to such a large display is impressive. The technology is more expensive than other methods of detecting touch, such as infrared, or using cameras, but it should be more accurate, says Colegrove. “Most people claim that you can detect the touches of 10 separate fingers at once,” she says, “and it is easier to reject accidental palm touches.”
Being able to support multitouch is especially important for very large displays, because it allows several people to collaborate on one display. Perceptive Pixel claims its technology can detect an “unlimited” number of simultaneous touches.
Other companies have scaled up projected capacitance to displays as large as 30 or 50 inches, says Colegrove, but these have only been produced in low volume. “This display from Perceptive Pixel sounds like it could be more suited to situations like boardrooms and other less specialized uses,” she says.
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