Motor having index detection mechanism used for disc apparatus and disc apparatus using such a motor

摘要

A spindle motor able to reduce leaking of magnetic flux of an index magnet to a magnetic head of a disc apparatus. In an axial gap type spindle motor having a rotor case rotatably supported by a base plate, an index magnet is provided to a face of the rotor case opposite to the base plate. A hall device is provided in an open space between a plurality of coils arranged radially on the base plate at a position opposite to the index magnet. A magnetic flux forms a closed loop by passing through the rotor case, and thus leaking of magnetic flux to the outside is reduced.