Patent ID: 7705835

Claim:
An apparatus for determining position of a stimulus in two axes on a surface, comprising: A transparent waveguide panel having a top and a bottom surface, which surfaces are parallel to each other, and at least one edge, which is perpendicular to said top and bottom surfaces; a light source directed to said at least one edge wherein said light source is configured to produce light that is contained within said waveguide by Total Internal Reflection; a light detector for producing an electrical signal representative of an image of light received; a first edge on said transparent waveguide panel having a first edge length, which first edge is perpendicular to said top and bottom surfaces; a second edge having a second edge length, which second edge is perpendicular to said top and bottom surfaces and which is at an angle to said first edge; wherein said light detector is positioned to receive light emitted by Frustrated Total Internal Reflection from said transparent waveguide when a physical stimulus is placed in contact with said top surface of said transparent wave guide; wherein said light source is directed to said first edge to produce a plurality of discrete light rays that are contained within said waveguide by Total Internal Reflection and wherein each of said discrete light rays has an emission location which is along the first edge length of said first edge; and wherein said light detector is comprised of a plurality of discrete light detecting elements distributed along the second edge length of said second edge, said light detecting elements configured to produce an electrical signal representative of light intensity emitted by Frustrated Total Internal Reflection at said second edge when a physical stimulus is placed in contact with said top surface of said transparent wave guide, each light ray detector having a light ray detection location.