an idea for a product

I like to hang out around www.makezine.com in part because of the fun, adventuresome attitude that they have, in part because of their recycling sorta mindset, and in part because they have great content, and in part because they have an awesome motto:

"Void your warranty, violate a user agreement, fry a circuit, blow a fuse, poke an eye out. Make: The risk-takers, the doers, the makers of things... Welcome to Make: Online! "

But anyway, one day while I was hanging out there, I got this idea. There are radio/ infrared systems that digitize a pen input from a normal whiteboard, but they require a big system of sensors stuck to the board, or special pens, etc. Probably the best, most widely known system like this is called a smartboard and pairs special pens for location awareness and a projector for live ink.

However, I have often wondered about being able to use an existing surface with a minimum of equipment to provide a touch input area... like for instance, take a real desk and section off an area to use for touch input. A microprojector could even be used. (There are now cameras that come with microprojectors to use for photo viewing). The core technology would be pretty heavy on the processing side, since it would use small piezo condenser mics to listen for taps on the surface, and then compare relative times for the sound to travel to pinpoint the touch location. Sound travels much quicker (and usually better) through solids than through air, so ambient noise shouldn't overwhelm it. I really think it might be able to work. It'd be lots of fun to try.

and no, I haven't done a patent search.