| 摘要 |
PROBLEM TO BE SOLVED: To optimize rigidity and self-resonance of a fluid dynamic bearing. SOLUTION: This fluid dynamic bearing system supports a spindle motor for driving, in particular, one of storage disk drives or a plurality of storage disks rotatably. This bearing system is provided with a bearing sleeve and a shaft accommodated in a bore in the bearing sleeve and rotatably supported with respect to the bearing sleeve. Mutually opposing surfaces separated by a bearing clearance filled by bearing fluid of the bearing sleeve and the shaft constitute at least one first radial bearing region. Diameter of the shaft is selected in such a way that a ratio of a bearing interval, that is, an interval between a clamp section of the shaft and a central part of the first radial bearing region to the diameter of the shaft is 0.9 or less, and the diameter of the shaft is, in particular, 3 mm to 5.0 mm. By this method, resonance frequency of the bearing is shifted to a high frequency band being not critical. COPYRIGHT: (C)2006,JPO&NCIPI
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