| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the driving state of a rotary body by compensating an error due to the eccentricity or tilt of a scale or the surface waving of the scale surface when the scale is fitted. SOLUTION: If a code wheel 4 is fitted obliquely to the shaft of a motor, the optical path of luminous flux reaching a photodetecting element 5b from a light emitting element 5a deviates in the rotating direction of the code wheel when a sensor 5 reads a part A and a part B in order, so the latter is slower in detecting speed than the former. At this time, a sensor 6 reads the part B and part A in order, so the mentioned optical path deviates reversely to the rotating direction and the latter becomes faster in detecting speed than the former. The influence of variation in the angle of a reflecting surface of the code wheel 4 can be removed by finding the means of the detection results of the sensors 5 and 6.
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