Linked by Thom Holwerda on Tue 10th Jul 2012 01:24 UTC
Microsoft "Microsoft and Perceptive Pixel Inc. (PPI) today announced that they have entered into a definitive agreement under which Microsoft will acquire PPI, a recognized leader in research, development and production of large-scale, multi-touch display solutions." Yes, Jeff Han is now a Microsoft employee. This demo still amazes me - from 2006. Before the iPhone. Before Android. Before the iPad. Remember that the next time you wind up in a discussion about who supposedly invented what.
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RE[5]: I built one too!
by Neolander on Wed 11th Jul 2012 12:03 UTC in reply to "RE[4]: I built one too!"
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I do remember that ;) The problem, however, would be to differentiate taps from below or the sides from taps from the top.

If you have only one homogeneous flat surface (as with the regular table with mics stuck on it that I saw), detecting taps on it is a simple 2D problem. Discriminate microphone signal pulses from background noise, find out correlations between them through signal processing algorithms, and you can estimate relative propagation delays. Then, knowing the speed of sound inside of the surface, you get relative spatial positioning information, that can itself be turned into absolute spatial positioning given some hardcoded calibration.

Now, if you are dealing with a thin box full of electronics (in which sound does not propagate homogeneously) and want to detect taps and friction in a 3D space, things become quite a bit more complicated. You need microphones in other places than the screen, and at least a rough model of how sound propagates inside of the device. Which is why I said that this could be an issue if we were to try to integrate acoustic touchscreens into small devices.

Edited 2012-07-11 12:06 UTC

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