| 摘要 |
PROBLEM TO BE SOLVED: To stably maintain rotation of the rotor-hub of a spindle motor, even when bearings having ceramic balls are used therein, by preventing one of the bearings from being subjected to loosening of a pre-load. SOLUTION: This spindle motor has first and second bearings 33, 34, fitted on a stationary shaft 31 which have respectively ceramic balls 33a, 34a, a stator 32 fitted on the stationary shaft 31 between the first and second bearings 33, 34, a rotor-yoke 38 fitted on an outer ring 33c of the first bearing 33 which constitutes a rotor-hub 40 together with a hub 39, a rotor-magnet 42 fitted in the inside of the rotor-yoke 38, a magnetic fluid oriented seal 46 held in the upper-end opening portion of the rotor-yoke 38, and a pre-load spring 48 and a washer 49 with respect to which they are provided between the magnetic fluid oriented seal 46 and the first bearing 33, and the washer 49 is fitted on the stationary shaft 31. At this time, outer rings 33c, 34c of both the bearings 33, 34 are fastened to the rotor-side, and the inner ring 34b of the second bearing 34 is fastened to the stationary shaft 31, and further, the inner ring 33b of the first bearing 33 is energized by the pre-load spring 48.
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