| 摘要 |
<P>PROBLEM TO BE SOLVED: To further stabilize the rotation of a spindle motor using a fluid dynamic bearing. <P>SOLUTION: The spindle motor SM includes: first and second conical bearing members 220 which are fixed to an axial member 210, and have conical outer surfaces 222; a rotor member 310 having first and second conical inner surfaces 314 whose inside diameters are expanded toward the outside; dynamic grooves formed at either the conical inner surfaces 314 and the conical outer surfaces 222; and lubricating oil 420 filled in micro gaps 410 between the conical inner surfaces 314 and the conical outer surfaces 222. Respective linear expansion coefficients α1, α2 and α3 of the axial member 210, the conical bearing member 220 and the rotor member 310 satisfy an expression of α3≥α2>α1, and an axial distance L between first and second points which are the same in inside diameter on the first and second conical inner surfaces 314, an inside diameter dimension D at the first point, and an inclination angle θ which is formed by the conical inner surfaces 314 between the faces vertical to their axes and themselves satisfy an expression of L>(D×tanθ). <P>COPYRIGHT: (C)2012,JPO&INPIT |
