Patent ID: 8511899

Claim:
A fluid dynamic bearing device, comprising: a bearing member having: a larger diameter inner peripheral surface; a smaller diameter inner peripheral surface; and a shoulder surface between the larger diameter inner peripheral surface and the smaller diameter inner peripheral surface; and an axial through-hole in which a lubricating fluid communicates, the bearing member being integrally formed by die molding together with the through-hole; and a shaft member inserted into an inner periphery of the bearing member, the shaft member being supported in a radial direction by means of a dynamic pressure effect of the lubricating fluid, which is generated in a radial bearing gap between the smaller diameter inner peripheral surface of the bearing member and an outer peripheral surface of the shaft member, wherein an opening on at least one end side of the axial through-hole is provided at a radially outer end of the shoulder surface, wherein the axial through-hole comprising: a first flow path having an upper end open to the shoulder surface; and a second flow path having a smaller sectional area than the first flow path. wherein the first flow path and the second flow path are formed in rectangular cross-sections, and wherein inner peripheral surfaces on radially outer sides of the first flow path and the second flow path are flush with each other.