| 摘要 |
A motor that can prevent damages on the fluid dynamic bearing. A ball is press-fitted into the end surface of the shaft body, and the ball is disposed in such a manner that the tip portion of the ball comes to the higher position with respect to the end surface of the annular body. When the shaft is at rest, the ball abuts against the upper surface of the counter plate, and the end surface of the annular body is brought into a state of being raised from the upper surface of the counter plate, so that the situation in which the end surface of the annular body and the upper surface of the counter plate are brought into almost fully touch each other can be avoided. Therefore, when the operation is started, the circulation speed of a fluid increases and a fluid layer is quickly formed. As a consequent, the fluid circularity blocking action, which could be occurred in the relate art, is avoided, and generation of scratch caused by starting rotation in the tightly sticked state can be positively prevented.
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