| 摘要 |
PURPOSE:To eliminate the shift of center of a memory disk for a drive shaft due to a change in temperature by forming the 1st hub half-body having a reference receiving surface with materials having approximately the same an expansion coefficient of line as that of a drive shaft and by forming the 2nd hub half-body including a pressing part with materials excellent in spring elasticity. CONSTITUTION:A metallic ling 16 inserted into a containing recess 14 of a hub half-body 6a is made of materials having approximately the same coefficient of line expansion as that of a drive shaft 25 of a memory reproducing device. The 2nd hub half-body 6b is obtained by projecting and molding a high molecular compound. When a hub 6 (hub-half bodies 6a and 6b) is inserted into a disk cartridge device containing a provided memory disk 2, the drive shaft 25 is pressed between a reference receiving surface 7 and a pressing part 8, and an arm 21 and a pressing head 22 are pushed away into the outside in the diameter direction, thereby producing bounding force. Utilizing this force, the reference receiving surfaces 7a and 7b abuts to a circumference surface of the drive shaft 25; therefore centering of the memory disk 2 for the drive shaft 25 is automatically carried out.
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