| 摘要 |
PROBLEM TO BE SOLVED: To surely chuck an optical disk having no center holes for chucking. SOLUTION: An optical disk 10 has no center holes for chucking, its information surface 14 is formed to be a straight plane, an information area 16 is provided in the full area of the information surface 14, a clamp area 20 of a circular projected shape is formed in a disk center on a backside 18, a chucking member 24 has a circular recessed part 26 fitted to the outside of the clamp area 20, and the circular recessed part 26 and the clamp area 20 are freely engaged with/disengaged from each other by a ball lamp mechanism 30. |
