Flexible disk drive comprising an index detection hall element having an improved detection sensitive condition of a magnetic field

摘要

A motor rotatably driving a flexible disk has a rotor having an external peripheral side surface on which an index detection magnet is mounted. A main circuit board mounts a control circuit for carrying out a driving control of the motor and extends in a direction perpendicular to a rotation axis of the motor. Attached to the main circuit board, a sub circuit board extends in a direction in parallel with the rotation axis of the motor at a position close to the external peripheral side surface of the rotor. Mounted on the sub circuit board, an index detection Hall element has a magnetic field detection surface which is disposed so as to oppose to the external peripheral side surface of the rotor.