Patent ID: 8711127

Claim:
A rectangular light-based touch-sensitive surface for an electronic device comprising: a plurality of light emitters arranged along one and only one side of a surface, each said emitter being activatable to emit light rays at a plurality of different angles across the surface; a plurality of light detectors arranged along the three remaining sides of the surface, each said detector being activatable to register detection values of emitted light beams, wherein light emitted from each said emitter is registered by two or more of said detectors; and a processor connected to said emitters and to said detectors, comprising a digitizing unit configured to receive the registered detection values and convert the values to digital data, the processor operable to: digitize an initial detection value registered by at least one of said light detectors prior to transmitting a light pulse of a designated emitter, the initial detection value representing an ambience light intensity; digitize a secondary detection value registered by at least one of said light detectors during transmission of light from the designated emitter; and control said light emitters such that each light pulse has a duration exceeding a time for said digitizing unit to produce the digital data.