| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical encoder based on three-grating theory which can accurately detect the origin position. SOLUTION: An optical linear encoder 1 comprises a movable grid plate 5 made of a semiconductor substrate, where a light transmitting grid group 3 for detecting A-phase signal and B-phase signal, photodiode groups 4A and 4B and a photodiode group 4C for detecting the origin position are formed. Also on a reflection grid plate 7, a reflection grid group 6C for detecting the origin position together with reflection grid groups 6A and 6B for detecting A-phase signal and B-phase signal. As the reflection grid group 6C comprises a reflection grid 63 consisting of a light transmitting slit pattern and a reflection grid 64 consisting of a light reflection slit pattern, a reverse signal can be obtained from the photodiode group 4C for receiving these reflection light image and the origin position of the moving grid plate 5 can be differentially detected based on them. COPYRIGHT: (C)2003,JPO
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