Patent ID: 7265339
Filing Date: 2007-09-04
Classification: G01D

Abstract:
1. An interpolating detector for generating a position signal indicating a change in the relative position of a code pattern comprising alternating light and dark stripes, said interpolating detector comprising: a photodiode array comprising a plurality of sets of photodetectors, each set labeled with an index i that runs from 0 to N, said i when said code pattern moves across said photodiode array, wherein F i and O i are constants and x denotes a relative position of said code pattern with respect to said interpolating detector, x changing by 2π when said code pattern moves a distance equal to the width of one light stripe and one dark stripe, and wherein N>2; an interpolation function generator that generates first and second interpolation functions, I a detector function generator that generates 4 detector signals, D a cross-point detector that generates a transition signal when I wherein said photodiodes have active areas having a shape such that said x values at which said interpolation signals cross said detector signals occur at integer multiples of 2π/m, for m greater than 4.