Patent ID: 8398308

Claim:
A disk drive device comprising: a base member; a bearing unit that is provided on the base member and is configured such that a shaft and a sleeve in which the shaft is inserted rotate relatively to each other; and a hub that is supported via the bearing unit, wherein the bearing unit includes: the shaft; a radial dynamic pressure groove that is provided on at least one of an inner circumferential surface of the sleeve and an outer circumferential surface of the shaft in order to generate radial dynamic pressure in lubricant; a sleeve concave portion that is formed on the inner circumferential surface at an end portion on a hub side of the sleeve; and a capillary seal portion that is formed by the sleeve concave portion and a shaft concave portion formed on the outer circumferential surface of the shaft, the outer circumferential surface of the shaft facing the sleeve concave portion, and a gap between the sleeve concave portion and the shaft concave portion is formed so as to expand toward the hub side of the sleeve, and wherein, assuming that: an outer circumferential diameter at a tilt starting end on a base member side of the shaft concave portion is D 0 ; an inner circumferential diameter at the tilt starting end on the hub side of the sleeve concave portion is D 1 ; a facing outer circumferential diameter of the shaft concave portion, which faces, in a radial direction, an inner circumference at the tilt starting end of the sleeve concave portion, is D 2 ; and a diameter of a most concave inner circumference of the sleeve concave portion is D 3 , D 2 is smaller than D 0 , D 3 is larger than D 1 , and the difference between D 3 and D 0 is larger than that between D 0 and D 2 .