US Patent 7202898 Self gating photosurface

A semiconductor surface is provided comprising a plurality of light sensitive pixels wherein each pixel of the plurality of pixels comprises an electronic circuit formed on or in the semiconductor surface, the circuit comprising: a photosensor that generates a signal responsive to light incident thereon at an output thereof; and circuitry that provides a signal responsive to a time lapse between a first time responsive to said signal and a reference time. There is also provided a 3D camera incorporating the semiconductor surface.