Patent attributes
A device and method for detecting the relative position of reference light includes a plurality of photodetector arrays arranged in a generally vertical row. Each array includes a plurality of photodetector elements arranged in a generally vertical array row. The photodetector elements in the arrays are arranged in a generally vertically oriented, extended row. Each of the photodetector elements provides an electrical output when illuminated with the light. A plurality of weighting circuits is provided, each weighting circuit being associated with a respective one of the plurality of photodetector arrays. Each weighting circuit provides a portion of the electrical output of the illuminated photodetector element in the array as a first reference signal related to the spacing of the illuminated photodetector element from a first end of the array row, and provides a portion of the electrical output of the illuminated photodetector element as a second reference signal related to the spacing of the illuminated photodetector element from the second end of the array row. The weighting circuit associated with each array row is connected to the weighting circuits associated with adjacent array rows. A plurality of output circuits are provided, with each output circuit associated with, and responsive to, the reference signals from connected weighting circuits. The output circuits determine the relative levels of the reference signals from the weighting circuits such that the position of the reference plane of light may be determined with respect to the detector device.
