Alphana Technology Co., Ltd.

Toshiki Maeda

Taketo Nonaka

Kazuhide Kamata

Morifumi Ohsawa

A bearing unit for a disk drive device is formed by a sleeve concave portion and a shaft concave portion, and is provided with a capillary seal portion in which the gap between the sleeve concave portion and the shaft concave portion is increased in diameter toward the hub side of the sleeve. Assuming that: the outer circumferential diameter at the tilt starting end on the base member side of the shaft concave portion is D; the inner circumferential diameter at the tilt starting end on the hub side of the sleeve concave portion is D; the facing outer circumferential diameter of the shaft concave portion, which faces, in the radial direction, the inner circumference at the tilt starting end of the sleeve concave portion, is D; and the diameter of the most concave inner circumference of the sleeve concave portion is D, Dis smaller than D, Dis larger than D, and the difference between Dand Dis larger than that between Dand D

Disk drive device provided with fluid dynamic bearing unit

A disk drive device has a hub so configured as to place and hold recording disks. Where the non-rotating eigenfrequency of resonance in a secondary rocking mode with the recording disks placed on the hub is defined to be F0 (Hz) and the rotational frequency of the hub is defined to be N (Hz), an extending part of the hub and a second cylinder part of the hub are formed such that the radial dimension of the extending part is smaller than the axial dimension of the second external cylinder part to satisfy to a relation F0&#x3e;N&#xb7;(3&#xb7;P+2).

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Shizuoka, Japan

Toshiki Maeda