Patent ID: 6674066
Filing Date: 2004-01-06
Classification: G01D

Abstract:
An optical encoder apparatus comprising:a scale with a grating portion; first light emitting means for irradiating said grating portion; first light receiving means for detecting a light beam from said grating portion when a light beam from said light emitting means is projected onto said grating portion, an incremental signal being obtained by detection by said first light receiving means resulting from the displacement of said scale; two or more mark portions formed on said scale; second light emitting means for irradiating said two or more mark portions; second light receiving means for detecting a light beam from said two or mark portions when a light beam from said second light emitting means is projected on said two or more mark portions, an origin signal being obtained by processing one or more detection signals detected by said second light receiving means in relation to the position of said scale; and synchronized origin position signal producing means for producing a synchronized origin position signal by processing the incremental signal and the origin signal.