True multitouch comes to large displays

True multitouch comes to large displays
The touch technology used in mobile devices could soon be available in much larger format screens only a matter of inches thick. New York based Perceptive Pixel, has launched an 82” touch display just six inches deep. “All of the tablet and phone manufacturers have established projected capacitance as the best way to do multitouch, but it has been really difficult to scale up,” said Perceptive Pixel’s founder Jeff Han speaking to

The company was created to commercialise work on multitouch technology that Han started whilst a researcher at New York University.

Projected capacitance senses fingers when they distort the electric field around a transparent layer of electrodes arrayed across the surface of a display. This has traditionally been hard to scale up because the noise created by the electronics in a screen interferes with the signals generated by touches.

Existing large format multitouch displays (by which we mean more than 8 touch points) are commonly based on a technique known as frustrated internal reflection. This involves shining IR light sideways through the glass surface of a display and using a rear mounted camera to track how fingers change the path of the light. However the camera must be mounted a set distance away and this can result in units up to a metre thick.

Perceptive Pixel has now developed signal processing algorithms that allow them to filter out the background noise and detect the small changes in capacitance that are required for multitouch. Earlier this year the company announced a 27” model based on the technology, and now an 82” inch device is also available.

Han says: “This now makes it possible for normal companies to use large multitouch displays for everyday work. They are thin enough to install in any boardroom.”

He expects to see them used in such applications as architectural practices, or collaborative videoconferencing.

According to Technology Review, Jennifer Colegrove, an analyst specialising 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 specialised uses," she said.

The video shows the new 82" device being demonstrated whilst driven by an NVIDIA graphics card 

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