| 摘要 |
PROBLEM TO BE SOLVED: To enable the rotation even in a high-speed rotating region by forming a magneto-optical disk which is mounted on a spindle and executes recording and reproducing in such a manner that the contacting area of a hub with a substrate and the projection area of the substrate of the magneto-optical disk satisfy a specific relation. SOLUTION: A hub 3 for magnetic clamping is mounted at the substrate in the state liberated from the substrate 1. The hub 3 is attracted by a magnet 4 mounted at the spindle 2. In such a case, the hub consists of a material having coefficient of thermal conductivity of >=0.05 (cal/ deg.C.cm.s). The projection area of the substrate, defined as X, and a contacting area of the hub 3 for magnetic clamping with the substrate, defined as Y, are specified to Y/X>=0.02, by which the friction force between the substrate and the hub is assured. The slip generated between the substrate and the hub by rotation may thus be prevented and rotation unevenness may be suppressed. Further, the holding power of the substrate increases in spite of the wobbling of surface induced by the rotation unevenness and the turbulence generated in a cartridge by rotation and, therefore, the effect of lessening the influence may be obtained.
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