| 摘要 |
A spindle motor using a hydraulic bearing is provided, wherein an R-face or C-face is formed on each of upper and lower edges of an outer periphery of a rotating disk portion rotatable integrally with a spindle, and the R-face or C-face is formed into a mirror-finished surface having a surface roughness of 0.3 s or less in Ra, preferably, 0.1 s or less in Ra. Alternatively, a recess may be formed in a portion, facing to each of the upper and lower edges of the outer periphery of the rotating disk portion, of an inner wall surface of the hydraulic bearing. Such a spindle motor provides a disk drive capable of suppressing a variation in rotational speed of the spindle motor caused by tilting of the spindle due to vibration and impact, thereby ensuring a stable recording or reproducing operation.
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