| 摘要 |
PURPOSE:To improve the surface precision of a surface being in contact with a centering member, to enhance the strength of a swollen part and to surely load it on a disk table. CONSTITUTION:This base is a disk base of a light transmissible resin material formed into a disk shape, and the swollen made part 13 provided with an engaging hole 15 with which the centering member of the disk table is engaged, a hub attaching surface 22 where a hub consisting of a magnetic plate is attached on the periphery of the engaging hole 15 and a loading reference surface 12 for the disk table is formed in the center of the disk base. Then, a ring-shaped projecting part 21 projecting from the outer periphery of the hub attaching surface 22 side of the engaging hole 15 to the attaching side of the hub is formed integrally. |
