Patent ID: 8821021

Claim:
A fluid dynamic bearing device, comprising: a shaft member comprising: a shaft portion, and a flange portion, the flange portion having a first end surface and a second end surface, the second end surface of the flange portion being disposed on an extreme end surface of the shaft portion, in an axial direction, wherein a through-hole is provided in the flange portion, the through-hole extending in the axial direction and opened at both the first end surface and the second end surface of the flange portion, a portion of the through-hole facing the extreme end surface of the shaft portion, wherein a first portion of the second end surface of the flange portion and the extreme end surface of the shaft portion are coupled to each other, thereby forming a coupling portion, the shaft portion and flange portion being integrated in a coupling manner by the coupling portion, wherein a second portion of the second end surface of the flange portion and the extreme end surface of the shaft portion are not coupled to each other, thereby forming a fluid path through the through-hole, wherein the fluid path is defined by the extreme end surface of the shaft portion and an inner wall surface of the through-hole, wherein the coupling portion of the second end surface of the flange portion and the extreme end surface of the shaft portion is subjected to laser welding, and wherein the coupling portion is formed by applying a laser beam through the through-hole from a side of the first end surface of the flange portion.