Patent ID: 9683871
Date: 2017-06-20
CPC Classifications: G01D

Claim:
1. An optical encoder, comprising: a light receiving unit; a scale comprising a first track having m patterns and a second track having s patterns, wherein a difference in number between the m and the s is Nd (where 1<Nd<m); and an arithmetic unit configured to generate a first intermediate signal by performing an arithmetic operation for a first track signal comprising m periodic signals and a second track signal comprising s periodic signals outputted from the light receiving unit by the first track and the second track, to calculate an absolute angle based on the first intermediate signal, to generate a second intermediate signal comprising one periodic signal per one rotation of the scale, and to calculate the absolute angle by analyzing the second intermediate signal in set resolution, wherein the second intermediate signal results from subtracting a result of an arithmetic operation for the first intermediate signal from the first track signal.