| 主权项 |
1. A vibration motor comprising:
a base portion arranged to extend perpendicularly to a central axis extending in a vertical direction; a shaft having a lower end fixed to the base portion, and arranged to project upward along the central axis; a circuit board arranged above the base portion; a coil portion attached to the circuit board, and arranged radially opposite to the shaft with a gap therebetween; a bearing portion attached to the shaft to be rotatable with respect to the shaft above the coil portion; a rotor holder attached to the bearing portion; a magnet portion including a plurality of magnetic poles, and attached to the rotor holder; an eccentric weight attached to the rotor holder; and a cover portion arranged to cover, at least in part, upper and lateral sides of the rotor holder and the eccentric weight, and fixed to an upper end of the shaft and an outer edge portion of the base portion; wherein the base portion includes:
a base magnetic portion made of a magnetic metal; anda base nonmagnetic portion made of a nonmagnetic metal, fixed to an edge portion of the base magnetic portion, and arranged to extend from the edge portion of the base magnetic portion perpendicularly to the vertical direction; the base magnetic portion includes a plurality of magnetic element portions arranged in a circumferential direction, and arranged at positions opposed to the magnet portion in the vertical direction; the base nonmagnetic portion includes a plurality of nonmagnetic element portions arranged to alternate with the magnetic element portions in the circumferential direction, and arranged at positions opposed to the magnet portion in the vertical direction; the base magnetic portion includes a first boundary portion where the base magnetic portion is in contact with the base nonmagnetic portion; the base nonmagnetic portion includes a second boundary portion where the base nonmagnetic portion is in contact with the base magnetic portion; an area where the first and second boundary portions are in contact with each other is defined as a boundary portion; and the base magnetic portion and the base nonmagnetic portion are arranged not to overlap with each other at any position outside of the boundary portion when viewed in the vertical direction. |
