| 摘要 |
In an optical rotary encoder, a stationary plate (1) having a zone plate (2) and a rotary slit plate (4) having slits (4a) are interposed between a light source (3) and a light receiving element (5). A suitable radius of the innermost circle of the zone plate (2) is selected so that the zone plates (2) provide a sufficient convergence of light for reduction of slit interval (hence for improvement of the detection precision) with a distance between the stationary plate (1) and the rotary slit plate (4) maintained at a value permitting the fabrication of the encoder. <IMAGE> |
