PROJECTION SYSTEMS FOR TOUCH INPUT DEVICES

摘要

In infrared touch input devices that detect and locate a touch object from the blocking of light paths propagating along the X,Y axes, an ambiguity arises when two touch objects are present. This ambiguity can be resolved by the provision of additional light paths angled to the X,Y axes. The present invention provides projection systems that include a light splitting element for splitting collimated sheet of light into two or more sets of beam paths, thereby providing the additional light paths for resolving the double touch ambiguity. In preferred embodiments the light splitting element is in the form of a prism film.