| 摘要 |
PURPOSE:To realize a small-sized and easy-to-manufacture encoder and to obtain high resolution by forming a pattern which has a light transmission area and a nontransmission area alternately on at least one surface of a rotary disk made of a light transmissive material. CONSTITUTION:The rotary disk 2 is formed of the light transmissive material like glass and a nontransmissive film of metal, etc., is formed on at least one surface. Then, the pattern 25 consisting of alternate light transmission areas 24 and nontransmission areas 23 is formed by employing photolithography and a slit group is formed through the pattern 25. This pattern 25 is formed by the photolithography, so slit width and intervals are made smaller than those when slits are formed and the accuracy is improved. A similar pattern is formed on the photodetection surface of a photodetecting element 41 and this pattern is formed integrally with the photodetection surface. The axial size of the rotary encoder is therefore reduced and the S/N ratio is increased. |
