WATER-IMMUNE FTIR TOUCH SCREEN

摘要

Disclosed herein are systems and methods for a water-immune FTIR touchscreen. An optically clear adhesive with an index of refraction between that of water and human skin in the infrared wavelength range is placed below a touchscreen interface substrate. Light beams with a glancing angle greater than a critical glancing angle determined by the index of refraction of the optically clear adhesive do not totally internally reflect at the interface of the touchscreen interface substrate and the optically clear adhesive. Light beams with a glancing angle below the critical glancing angle totally internally reflect. A glancing angle that totally internally reflects at the substrate/optically clear adhesive interface will also totally internally reflect at an interface of the substrate and any water on the surface of the substrate, rendering the touchscreen immune to the effects of water.

主权项

1. A water-immune frustrated total internal reflection (FTIR) touchscreen, comprising:
a lower substrate layer comprising a first index of refraction; an upper substrate layer comprising a second index of refraction and configured to propagate a light beam, the upper substrate layer being situated above the lower substrate layer; an optically clear adhesive layer comprising a third index of refraction, the optically clear adhesive layer being situated between the lower substrate layer and the upper substrate layer, wherein the third index of refraction is greater than or approximately equal to an index of refraction for water and less than an index of refraction for human skin.