Patent ID: 7087888
Filing Date: 2006-08-08
Classification: G01D

Abstract:
1. An optical encoder, comprising: a scale having an optical grating formed thereon; a light source for irradiating the optical grating on the scale with light; photoelectric receiving elements for receiving light from the light source through or reflected from the optical grating on the scale to output signals corresponding to the received light; and a signal processing circuit, including an electrical division circuit and a plurality of comparators, for processing a pair of output signals having 90° phase difference with each other, the pair of output signals corresponding to the received light on the photoelectric receiving elements thereby detecting an amount of relative movement of the scale with respect to the photoelectric receiving elements, wherein the electrical division circuit receives a plurality of first signals relating to the pair of output signals and having the phase difference of 0°, 90 °, 180°, and 270°, respectively, and outputs a plurality of second output signals having the divided phases of the first signals, and wherein a pair of signals, selected from the plurality of the second output signals having 180° different phases with each other and substantially equal amplitudes with each other, are inputted to a pair of input terminals of each of the plurality of comparators.