# what are the mechanics behind iPod's touch screen?

**URL:** <https://boards.straightdope.com/t/what-are-the-mechanics-behind-ipods-touch-screen/420410>\
**Category:** Factual Questions\
**Created:** [September 25, 2007, 12:04pm UTC](https://boards.straightdope.com/t/what-are-the-mechanics-behind-ipods-touch-screen/420410 "2007-09-25T12:04:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![RumMunkey](https://avatars.discourse-cdn.com/v4/letter/r/b19c9b/32.png) [@RumMunkey](https://boards.straightdope.com/u/RumMunkey)\
**Post date:** [September 25, 2007, 12:04pm UTC](https://boards.straightdope.com/t/what-are-the-mechanics-behind-ipods-touch-screen/420410/1 "2007-09-25T12:04:03Z")

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I picked up a brand new 16GB iPod touch yesterday. Man, this thing is impressive.

I’m usually pretty good at grasping a basic understanding of how these type of things works just by playing with it a bit, but I’ll be damned if I can’t figure out how this touch screen works!

It doesn’t appear to be the same as touch screens you see on ATMs or on POS systems at the grocery store.

It’s a hard glass, not a soft clear overlay like the touch screen of my Sony Commander remote. I can’t see any sort of sensors or receptors when I look closely at the screen.

I think it has the potential to be revolutionary. I can see many future applications for this. From everything to in-car entertainment systems to laptops to remote controls, to video game systems, to just about anything else you can imagine.

What exactly are the mechanics behind the touch screen?

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**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\
**Post date:** [September 25, 2007, 12:24pm UTC](https://boards.straightdope.com/t/what-are-the-mechanics-behind-ipods-touch-screen/420410/2 "2007-09-25T12:24:19Z")

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I believe they use Frustrated Total Internal Reflection - a light is shone through the edge of the glass/plastic - you don’t see it because it reflects back and forth through the material (like light in a fibre optic cable) - when you touch the glass, this stops it reflecting internally and alters the characteristics of the beam exiting the other edge of the material - from this change in characteristics, the position of the touch(es) can be calculated.

[http://multi-touchscreen.com/Frustrated-Total-Internal-Reflection](http://multi-touchscreen.com/Frustrated-Total-Internal-Reflection)