Patent ID: 7477241

Claim:
An optical touch panel comprising: a support defining a generally planar surface; an optical illumination assembly arranged along and above at least part of a periphery of said support to define a light curtain region, said assembly including: at least one light guide, said at least one light guide having at least one extended light scatterer extending along a substantial portion of said at least one light guide, said at least one light guide having optical power and at least one light transmissive region having a focus located in proximity to a discontinuity, wherein said at least one light scattering discontinuity extends along said periphery, wherein said at least one light guide partially surrounds said light curtain region; at least one light source arranged for directing light along said at least one light guide, said optical power of said at least one light guide and said at least one extended light scatterer being operative to direct light, received from said at least one light source along said at least one light guide and scattered by said at least one light scatterer, generally in a plane parallel to said generally planar surface such that every location in said plane receives light from generally every location along said light guide; at least one light detector, arranged to detect changes in the light received from said optical illumination assembly produced by the presence of an object in said light curtain region; and a detection circuitry receiving at least one output from said at least one light detector and providing an output indication of the two dimensional location of object impingement in said light curtain region.