Patent ID: 7645073

Claim:
A hydrodynamic bearing device comprising: a shaft; a flange which has a shape which is substantially disc shape and is fixed to one end of the shaft; a sleeve having the shaft and the flange inserted into a space defined by an inner surface with a predetermine gap being placed between the shaft and the flange and the inner surface, the sleeve having an inner surface portion which opposes an outer peripheral surface of the flange which has an inner diameter smaller in end portions in an axial direction than in a central portion; a thrust plate which closes an opening end of the sleeve and which is opposed to the flange; and a lubricant filled in a gap between the shaft and the sleeve, a gap between the flange and the sleeve, and a gap between the flange and the thrust plate, wherein the inner surface portion of the sleeve which opposes the outer peripheral surface of the flange forms a true circular arc or elliptic circular arc along the axial direction.