| 摘要 |
PURPOSE:To execute a measurement with high accuracy by generating one piece of pulse at every one rotation by a rotary sensor which has been attached to a revolving shaft, executing a scan and a data input many times within a time between the pulses, and obtaining their average value. CONSTITUTION:As for a revolving shaft 1, generally the surface is uneven, and the rotation center does not coincide entirely with the center of the revolving shaft 1. Accordingly, a count number (a) corresponding to a size of a gap A formed by the revolving shaft 1 and a light shielding plate 2 is varied hourly extending from the maximum value amax to the minimum value amin, as the revolving shaft 1 rotates. In the same way, a count number (b) corresponding to a size of a gap B formed by a sheet 3 and the light shielding plate 2 is varied hourly from bmax to bmin, even if thickness of the sheet 3 is constant. A reflecting mirror 6 of a scanning mechanism is scanned at a higher speed than that of a rotation of the revolving shaft 1, values of 1 and (b) are measured many times during one rotation of the revolving shaft 1, and their average value is calculated by an operator 15, by which an eccentricity of the revolving shaft 1 and an error caused by unevenness can be reduced.
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