| 摘要 |
PURPOSE:To detect rotation highly accurately, by providing at least two detectors at positions, which are symmetrical with respect to the point of a rotary shaft, and removing the detection error due to the deviation of the center of a light shielding plate from the center of the rotary shaft. CONSTITUTION:Two photosensors PS1 and PS2 are arranged at positions, which form point symmetry with respect to a rotary shaft 1 in association with a light shielding plate 2, which is attached to the rotary shaft 1. The photosensors PS1 and PS2 have a pair of a light emitting element 5 and a light receiving element 6, which are attached to a U-shaped base 4. The signal output of the pulse train corresponding to the rotation of the light shielding plate is obtained from each light emitting element 6. The outputs of the photosensors PS1 and PS2 are added. Thus the error due to the effect of the eccentricity of the rotary shaft 1 and the light shielding plate 2 can be eliminated.
|
