Data erasure apparatus, data erasure method and method for writing servo patterns on recording disk

摘要

To prevent a spindle motor from stopping rotation while data on a magnetic disk is being erased by using a permanent magnet 151. Data in the whole area of the magnetic disk 113 is erased as a consequence of the magnetic disk 113 rotating in the magnetic field of the permanent magnet 151 located so as to face a part of the magnetic disk 113. A back yoke 161 is located so as to face a base 111. The back yoke 161 gives a magnetic force to the spindle motor in the opposite direction of the magnetic force of the erasing permanent magnet 151 so that the fluid dynamic bearing spindle motor can retain the rotation as required without stopping rotation.