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[2]: I built one too!
by Laurence on Tue 10th Jul 2012 13:42 UTC in reply to "RE: I built one too!"
Laurence
Member since:
2007-03-26

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.

Reply Parent Score: 2

RE[3]: I built one too!
by Alfman on Tue 10th Jul 2012 14:26 in reply to "RE[2]: I built one too!"
Alfman Member since:
2011-01-28

Just to entertain the idea and play devil's advocate here:

If the system relies on the speed of sound reaching sensors, I suspect that's usually fairly constant in most environments. I'd expect the air density to be consistent across the surface, windspeeds of 15+ MPH (sorry, Km/H) would be unusual and that's still only about 1% error against the speed of sound.

Tuning the sensors to a specific frequency should be trivial, and one could even implement frequency hopping and/or multi-spectral tones which are unlikely to be duplicated in any natural environment.

Whether it is superior or not to capacitive touchscreens somewhat misses the point that it may be "good enough" and far more affordable. It could work on natural surfaces too, like walls and floors.


Edit:
Thinking about it further, it should be possible to compensate for the wind-speed issues as well by pairing up the microphones with speakers and detecting the sound waves from the other microphones. This could additionally help automatic calibration and maybe even adhoc placement of the microphones on arbitrary surfaces without any frame at all.

With an appropriate sensor array, I think an acoustic system might be made to work in 3 dimensions. Capacitive sensors can't really do that.

Edited 2012-07-10 14:38 UTC

Reply Parent Score: 3

RE[4]: I built one too!
by zima on Tue 10th Jul 2012 15:55 in reply to "RE[3]: I built one too!"
zima Member since:
2005-07-06

windspeeds of 15+ MPH (sorry, Km/H) would be unusual

Kelvin-meter per Henry? That does seem like an unusual wind ;)

Reply Parent Score: 2

RE[4]: I built one too!
by Laurence on Wed 11th Jul 2012 09:42 in reply to "RE[3]: I built one too!"
Laurence Member since:
2007-03-26

I think you've missed my point because wind speed should never need to come into the equation unless you're using the general purpose front mic (which, quite frankly, is a silly idea).

Reply Parent Score: 2

RE[3]: I built one too!
by Neolander on Tue 10th Jul 2012 15:07 in reply to "RE[2]: I built one too!"
Neolander Member since:
2010-03-08

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

Reply Parent Score: 1

RE[4]: I built one too!
by zima on Tue 10th Jul 2012 16:03 in reply to "RE[3]: I built one too!"
zima Member since:
2005-07-06

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.

Or it could be exploited to expand possible control schemes (like PS Vita with a touchpad on its back; and, IIRC, some time ago we discussed how this could be one of the approaches for "more 3D" control than touchscreens allow)

Reply Parent Score: 2

RE[4]: I built one too!
by Laurence on Wed 11th Jul 2012 09:57 in reply to "RE[3]: I built one too!"
Laurence Member since:
2007-03-26


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.

I understand the acoustics of it all (I've spent a lot of time working with mics as well). While I appreciate that outside noises isn't a huge issue most of the time, it will be an issue some of the time. For example, in night clubs where the sound system is well tuned for punchy kick drums. Such a touch pad under those conditions could be worse than useless.

You also then have to account for the amplitude of the sound (depending upon how heavy handed the user is), the different refractive properties of the casing for each unique phone handset and the subtle differences in the tune of the touch depending upon the make up of the casing (crude example: tapping a metal table produces a different sound to tapping a plastic table).

So I just think the amount of code that would have to go into understanding the difference between sounds originating from physical contact and those from external sources could amount to a more complex solution than having sensors detect physical contact via the resistance of the users finger. Though I will grant you that some of the above can be configured at run time by a control panel-type app - but even then, that means you don't have an "out of the box" solution unlike with the current method.

Further more, attaching a new phone case (eg rubber sleeve or patterned cover) would then also change the acoustics and thus potentially break the touch pad. Which would be a terrible step backwards in terms of usability.

Don't get me wrong, I think the mic'ed method is a fascinating idea and it sounds like great fun for a lab / home environment. I just think it's not better (or even practical) than current capacitive inputs.

Reply Parent Score: 2