Yesterday, Sony revealed its model MT27i as the Xperia Sola, featuring an innovative new input technology. Rather than only detecting when your fingers actually touch its screen, the Sola will be able to track fingertips before they even make contact with the glass, letting apps detect these new “hover” events. Called “floating touch”, it all sounded very cool, but Sony wasn’t too big on the details at first. Now the company has taken the time to explain just how this new finger tracking works, and how developers might take advantage of it.
Technically, any capacitive sensor can detect fingertips at a distance, but for the kind used in smartphone displays, called a mutual capacitance sensor, this distance is so small as to effectively render it contact-only. There’s another kind of sensor, which relies on an effect called self capacitance, which is much more sensitive, and able to detect fingertips hovering up to two centimeters above the screen. The problem with that kind of setup is that it can’t handle multi-touch tracking.
Sony realized that neither one of these systems would allow it to have floating touch at the same time as normal multi-touch recognition, so it decided to use both systems. As a result, multi-touch works when you’re physically touching the screen, but only a single finger can be detected in floating touch.
Ice Cream Sandwich adds support for hover events to Android’s API, opening the door for apps that can respond differently to these two distinct types of input.