| 摘要 |
PURPOSE:To ensure highly stable and accurate control for positioning of the revolving center of a recording medium, by using the bias power of an elastic matter to obtain a contact between a pair of reference sides formed at a center hole of a center hub part and a spindle. CONSTITUTION:A magneric disk 1 and a center hub part 3 are set on a flange holder 14, and the center hole 5 of the part 3 is set at a spindle 13. Then the disk 1 is held between a record/reproduction head 19 and a pad 20. The revolutions of the disk 1 are prvented by the head 19 and the pad 20 and therefore a drive pin 17 moves with a contact kept with the bottom surface of the part 3 and is set at a drive pin insertion hole 8. Then the pin 17 is engaged with the hole 8 by a compressed spring 18. In this case, the part 3 is put into the spindle 13 by attraction of a magnet 16 and therefore reference sides 6a and 6b have a contact with the spindle 13 with the force of elastic matters 7a and 7b for positioning. If the same diameter is given to the spindle 13 between the record and reproduction modes, the revolving center position of the disk 1 can always be regulated accurately despite some fabrication error of the center hole 5.
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