| 摘要 |
PROBLEM TO BE SOLVED: To suppress the effect of a leaked magnetic flux from a permanent magnet for motor driving given to an adjacent magnetic head, and the effect of a noise caused by vibration generated in a cover at a high-speed rotation. SOLUTION: This device is provided with a magnetic disk medium, a spindle shaft 23, a permanent magnet 24 fixed to the spindle shaft 23, a cover 30 brought into contact with the end part of the spindle shaft to cover the permanent magnet 24, and an actuator for positioning a magnetic head. In this case, the flat plate 32 made of a magnetic material is attached to a position opposite the permanent magnet 24 of the cover 30. By attaching the flat plate 32 to the cover 30 to increase the entire weight of the cover, the intrinsic frequency of the entire cover is changed, and noise is suppressed by preventing resonance with vibration generated by the high-speed rotation of the spindle shaft 23. In addition, the drawn patterns of a step shape is formed over the full periphery of the cover, and the resonance of the cover is prevented by setting them noncoincident with the number of poles of the permanent magnet 24.
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