| 摘要 |
PROBLEM TO BE SOLVED: To prevent that dust attached to a stator base enters into the inside of a case. SOLUTION: A stator base 21 of a spindle motor 20 is attached to the back of a bottom plate 11a of a case 11, also, a disk 31 is mounted on a hub 25 held freely rotatably on the data base 21, when this disk 31 is housed freely rotatably in the case 11 in which the mounted disk 31 is hermetically sealed, stepwise cylindrical part 25a1-25a4 of a plurality of steps are formed at an outer peripheral part of the hub 25, also, the stepwise cylindrical part 25a1 of the maximum outer diameter out of stepwise cylindrical parts of a plurality of steps is faced to a circular concave part 11a2 formed at the back of the bottom plate 11a of the case 11, while stepwise cylindrical parts 25a2-25a4 formed to smaller diameter than the stepwise cylindrical part of the maximum outer diameter is inserted into a through round hole 11a3 having smaller diameter than the stepwise cylindrical part of the maximum outer diameter pierced at the inside of the circular concave hole 11a2 in the bottom plate 11a of the case 11, and the disk 31 is mounted at an opposite side of the stator base 21 for the through round hole. COPYRIGHT: (C)2009,JPO&INPIT
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