| 摘要 |
An optical encoder equipped with an origin detection apparatus has a scale (13) provided with an optical grating, a plurality of light receiving elements (14) that is provided in association with the pitch of the optical grating and movable relative to the scale (13) and a light source (11) that illuminates the light receiving elements (14) with light through the scale (13). An optically discontinuous portion (13b) is provided in the optical grating of the scale (13), a change of a light beam that occurs over a certain length of section at the time when a light beam corresponding to the discontinuous portion (13b) is incident on the light receiving elements (12), a change occurring in that section is detected, calculation is performed, and an origin position is detected from the result of the calculation. |
