| 摘要 |
PURPOSE:To ensure the stable writing/reading actions despite the occurrence of a temperature change by providing a compensating part at a position where the distortions produced at an essential distortion generating part for flange and boss parts are compensated. CONSTITUTION:A rotary shaft 7 is provided together with a boss part 2, a flange part 3, a hub 12 for attachment of a disk 11, etc. An essential distortion generating part 21 including a cut part, a recess part and a thick part of a substrate leader line 24, etc., is provided at the part 3 owing to the positional relation with a device main body part 20. A groove part 28 serving as a distortion compensating part 27 for the part 21 is formed at a position symmetrical to the axial center C of the part 21. In an operation state the part 3 has the heat expansion with the temperature rise of a spindle motor 1. Thus the part 2 and the shaft 7 are turned in a fixed direction respectively to cause the distortions. These distortions are offset via the part 27. Thus it is possible to prevent a minute angle change caused by a heat change and to ensure the stable writing/reading actions.
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