| 摘要 |
PROBLEM TO BE SOLVED: To weaken force for separating a clamper from a turn table in a state having no disk to an extent of the separation force in a state having the disk. SOLUTION: The turn table 12 has a cylindrical part 16 to be inserted into a central hole of a disk and a placing surface 18 for supporting the disk. The clamper 14 is adsorbed to an upper surface of the turn table 12 by magnetic force and the disk is held between a depressing surface 28 thereof and the placing surface 18 of the turn table 12. A circular hole 22 is formed at a center of an upper surface of the cylindrical part 16 and a cylindrical positioning projection 34 to be inserted into the circular hole 22 is formed at a center of a lower surface of the clamper 14. An outer peripheral surface of the projection 34 is formed to a tapered surface 50 having an outer diameter which becomes larger toward a root direction. When the clamper 14 is adsorbed to the turn table 12 in a state having no disk, a mouth edge of the circular hole 22 comes into contact with the tapered surface 50 and thereby entry of the projection 34 into the circular hole 22 is regulated at the time point when a distance between the depressing surface 28 and the placing surface 18 is a little shorter than plate thickness of the disk.
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