"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.(but only 6 inches deep)"