US Patent 7728269 Photoarray for detecting time-dependent image data

A photoarray includes a one-dimensional or two-dimensional array of cells, each having a photosensor generating a sensor signal dependent on a light intensity at the cell, a first capacitor charged by a time-derivative of a current, at least one threshold detector detecting if a voltage over the first capacitor exceeds a threshold value and generating an output signal if it does, and a discharge device for discharging the first capacitor after occurrence of the output signal. Such a cell generates an event only when the incoming light intensity changes, which reduces the amount of data to be processed from the photoarray.