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Originally Posted by sgeiger
I could be mistaken, though the inherent problem with an "above-the-display" IR emitter system that others are suggesting is that all you need to get some dust or another obstruction at the edges of the screen bevel and the display and all of a sudden it can't "see" anymore. Seeing as, to my knowledge, this isn't the case, I doubt this is how it functions. (also you'd figure the Kobo website would have "make sure the edges of your screen are clean" as a suggestion for people who's screens aren't responding to touch.) Having done some research on modern IR displays, I've read that they work by beaming light through a layer of plastic above the display, and when you apply pressure, the light refracts differently and this is detected by the device.
Also seeing as the kobo vox uses the same IR touch display (again, Kobo flat-out states it's IR on their website), and there is clearly no space at the screen bevel to have incorporated IR LEDs or photoreceptors, I think it's safe to say the IR beaming/reception takes place within the first layer of the panel, not above it.
If you've ever tinkered with a video camera (even a phone's camera), you can see that IR devices, like TV remotes, emit light visible to the camera. Simply put: cameras can see infrared light. If you look through a camera at the edges of the screen of the kobo when it's off VS on, you'll see no difference. If there were hundreds of IR emitters along the edges, I think the edges of the display would appear illuminated when looking through a camera.
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IR tech is neither capacitive nor resistive. There IS a thin bevel along the edges of the screen (at least on the KT, can't say claim anything for a Vox since I don't own one) ABOVE the actual screen. The way it works is that a large enough area of the IR beam has to be broken for it to register. Thus the ineffectiveness of thin stylus' and no particular worries about mild dirtying of the screen since anything relatively small will not affect the responsiveness. However it has been noted that with some types of lighting the KT seems to respond a bit quirky. Perhaps it has a weak IR component that acts as noise. As for cameras seeing IR they have to be in the path of the beam. Given it's not exactly a laser, the bevel may be shaped to focus the IR beam so that it doesn't stray much (maybe less than a mm) above the actual screen and make it difficult for cameras to catch IR light. The receptors on the other hand may be able to receive light at a slightly higher angle to makeup for manufacturing variances. There could also be an intermittent beam rather than a continuous one to save power that could also contribute to making it difficult to detect with a camera.