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[3]: I built one too!
by Neolander on Tue 10th Jul 2012 15:07 UTC in reply to "RE[2]: I built one too!"
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I'm not convinced that a microphoned approach would be any more reliable than capacitive sensing. In fact I'd wager it would be far less reliable as it would be subject to outside interference. It's one thing having such a technique work in lab conditions, but when you're at a noisy train station and the phone is in your pocket or trying to detect multi-touch gestures under such environments. Certainly in the for former scenario, you could run the risk of triggering all sorts of false positives. Sure, with enough code you could account for most scenarios, but then you'd create something more complex then detecting the variable voltage change from a persons fingers.

Outside noise is not necessarily that much of an issue. If you stick the piezos inside of the device's casing, they will be far, far more sensitive to finger tapping and friction on the device's casing than to outside noise, since there's a lot of acoustic reflection going on at the air-casing interface. That, and acoustic power decreases as the square of the distance that is travelled from the source. To see how big the difference is, just gently tap the surface of a microphone when recording sound : you should get a peak that is far more intense than anything you were recording, even for a very gentle tap.

Pockets are indeed an issue, but on this front microphones are just as bad as capacitive touchscreens, which will also run amok if you forget to turn off your phone before putting it in your pocket. One specific pitfall of acoustic sensing is friction on the back or the sides of the device during device use though. Accounting for these could indeed require complex noise cancellation systems.

Edited 2012-07-10 15:09 UTC

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