Patent ID: 7073630

Claim:
In combination: a fluid dynamic pressure bearing having a stepped sleeve; a flanged shaft rotatably fitted into the stepped sleeve; and an annular lid covering one side of the stepped sleeve and serving as a thrust presser member; wherein fine gaps are formed between the flanged shaft, the stepped sleeve, and the annular lid, and lubricating oil is filled in the fine gaps; and a fluid injection apparatus for injecting lubricating oil into the fluid dynamic pressure bearing, the fluid injection apparatus comprising a bearing holding base having a bearing holding surface accommodating an O-ring for supporting the fluid dynamic pressure bearing; a bearing fixing device for urging the fluid dynamic pressure bearing toward the bearing holding surface so that a seal space is defined by the O-ring between the bearing holding surface and the fluid dynamic pressure bearing; a vacuum pump for evacuating an inside of the fluid dynamic pressure bearing through an opening in the fluid dynamic pressure bearing facing the bearing holding surface; an oil tank for storing lubricating oil that is to be injected into the opening in the fluid dynamic pressure bearing; an oil recovery tank for recovering lubricating oil that has not been injected into the fluid dynamic pressure bearing; an injection passage connecting the oil tank and the seal space; a decompression passage connecting the seal space and the vacuum pump through the oil recovery tank; an injection side valve provided in the injection passage; and a decompression side valve provided in the decompression passage.