Optical rotary encoder with correction method reducing variation of a distance between a rotation body and a light receiving unit

摘要

An optical rotary encoder includes a light source, a rotation body including a reflecting diffraction grating, a light receiving unit including a plurality of light receiving elements, a synthetic unit that combines output signals output from the plurality of light receiving elements to obtain a signal, which represents a fringe pattern component at a certain cycle, included in a light reflected by the reflecting diffraction grating and, and a detection unit that detects a direction based on a first signal and a second signal, the direction being a direction in which a distance between the rotation body and the light receiving unit varies, the first signal and the second signal being obtained by the synthetic unit, the first signal indicating a fringe pattern component having a cycle shorter than the certain cycle, the second signal indicating a fringe pattern component having a cycle longer than the certain cycle.

主权项

1. An optical rotary encoder comprising:
a light source that emits light; a rotation body that includes a reflecting diffraction grating, the reflecting diffraction grating including a certain-periodic structure; a light receiving unit that includes a plurality of light receiving elements, each of the plurality of light receiving elements outputs an output signal corresponding to an amount of received light; a synthetic unit that combines output signals output from the plurality of light receiving elements which receive respective lights, the respective lights being emitted from the light source and reflected by the reflecting diffraction grating, the synthetic unit obtaining a signal that is included in the reflected light and represents a fringe pattern component at a certain cycle; and a detection unit that detects a direction based on a first signal and a second signal, the direction being a direction in which a distance between the rotation body and the light receiving unit varies, the first signal and the second signal being obtained by the synthetic unit, the first signal indicating a fringe pattern component having a cycle shorter than the certain cycle, the second signal indicating a fringe pattern component having a cycle longer than the certain cycle.