Patent ID: 7019278

Claim:
A device for detecting the relative position of reference light, comprising: a plurality of photodetector arrays arranged in a generally vertical row, each array including a plurality of photodetector elements arranged in a generally vertical array row, such that the photodetector elements in said arrays are arranged in a generally vertically oriented, extended row, each of said photodetector elements providing an electrical output when illuminated with said reference light, a plurality of weighting circuits, each weighting circuit associated with a respective one of said plurality of photodetector arrays, each weighting circuit providing a portion of the electrical output of each photodetector element in the array as a first reference signal related to the spacing of the photodetector element from a first end of said array row, and providing a portion of the electrical output of each photodetector element as a second reference signal related to the spacing of the photodetector element from the second end of said array row, the weighting circuit associated with each array row being connected to the weighting circuits associated with adjacent array rows, and a plurality of output circuits, each output circuit associated with and responsive to the reference signals from connected weighting circuits, for determining the relative levels of said reference signals from said weighting circuits such that the position of said reference light with respect to said detector device may be determined.