Keypad embedded in the palm

IT'S A creepy sensation, having a little keyboard permanently emblazoned on the back of my hand. No matter what I do – shake my hand or wave it – I can't make it go away. Creepier still are the soft tingles on my skin as each "key" is pressed, like a low-frequency electronic buzz.
I am in Masatoshi Ishikawa's lab at the University of Tokyo, Japan, where the latest in interactive projections is being demonstrated for the first time. The set-up is in two parts: one is a projection that beams the outline of computer keyboards or cellphone keys onto any object, such as your hand.

Projecting interactive outlines of devices has been done before, but it is a lot trickier doing it on a moving object. Ishikawa's system detects and maps the position of an object 500 times per second and projects an image onto it. It automatically controls a camera's pan and tilt angles to ensure it is locked onto an object no matter how fast it moves. Ishikawa once demonstrated this technology by tracking a table-tennis ball in play.

The set-up also has a tactile angle. The information about the exact location of your hand and the orientation of the projected keypad is fed to a second system, called the Airborne Ultrasound Tactile Display. This makes the illuminated points on your hand or body slightly tingle with what feels like a jet of air. It's an odd feeling, but I find it makes the projected image seem more real.

The sensation on the hand is generated by sound beamed by 2000 or so ultrasonic wave emitters, says its developer Hiroyuki Shinoda, also at the University of Tokyo. The carefully timed and directed sound beams can make any spot vibrate within a given cubic metre.
The combined system has already attracted interest from the auto, medical and gaming industries, says Ishikawa. View Picture here
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