Patent ID: 7432893

Claim:
Apparatus for detecting the location of an object comprising, in combination, a transparent panel defining two opposing planar surfaces and having an index of refraction greater than air, a light detector optically coupled to said panel for detecting light transmitted within said transparent panel at a plurality of spaced apart detection points located at or near the periphery of said panel, a first light source optically coupled to said panel for transmitting light into said panel at an angle so that light from a first position propagates by internal reflection within said panel between said two opposing planar surfaces to a first set of said spaced apart detection points, a second light source optically coupled to said panel for transmitting light into said panel at an angle so that light from a second position propagates by internal reflection within said panel to a second set of said spaced apart detection points, and a data processor connected to said light detector for processing signals indicating changes in the light intensity at individual ones of said first and second sets of detection points to produce an output indication which specifies one or more locations on said surfaces where the presence of an adjacent object has caused a change in the internal reflection characteristics of said panel.