FLUID DYNAMIC PRESSURE BEARING, SPINDLE MOTOR PROVIDED WITH THE FLUID DYNAMIC PRESSURE BEARING, AND RECORDING DISK DRIVE DEVICE PROVIDED WITH THE FLUID DYNAMIC PRESSURE BEARING

摘要

A fluid dynamic pressure bearing is constituted in which a shaft member, including thrust plates 5 engaged with small-diameter portions at both ends of a shaft 1, is relatively rotatably combined with a bearing member via radial and axial dynamic pressure bearings. The bearing member includes a casing 3, a sleeve assembly body engaged to the casing 3, and seal rings 6 engaged to end portions of the casing 3. The sleeve assembly body is constituted by two or more sleeve elements 2 and a spacer sleeve element 4 coaxial with and sandwiched between the sleeve elements 2. Capillary seal portions 9 are formed between the thrust plates 5 and the seal rings 6. Highly accurate finishing of the dynamic pressure bearing portions, capillary seal portions, etc. can easily be accomplished by an easy, highly accurate processing, even if the shaft member or bearing member of a spindle motor becomes longer as a memory capacity of a memory device is increased.