| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method and apparatus for positioning a disc-shaped body whereby its accurate positioning is realized by an automatic control with a simple configuration. SOLUTION: Putting a wafer (disc-shaped body) 10 on a rotational stage 2 whose center of rotation is present on a positioning point, the distance ranging from the center of rotation to the peripheral edge of the wafer 10 is measured every predetermined rotational angle by a distance measuring sensor 8 to compute both the discrepant angle and discrepant distance between the center of rotation and the center of the wafer 10. After rotating the rotational stage 2 by the discrepant angle, in the state of removing temporaily the wafer 10 from the rotational stage 2, the rotation of the rotational stage 2 is transmitted to a cam 4 by a clutch 5 to move linearly the rotational stage 2 by the discrepant distance. Then, when putting again the wafer 10 on the rotational stage 2, since the center of the wafer 10 coincides with the center of rotation, the positioning of the wafer 10 is performed by returning the rotational stage 2 to its original position through the cam 4.</p> |
