Patent ID: 8339724

Claim:
An apparatus for inducing a magnetic bias in a magnetic recording disk, comprising: a soft magnetic material member having a shape comprising two opposing recesses, wherein the two opposing recesses include an upper recess and a lower recess; a first magnet disposed within the upper recess, wherein no other magnet of a different polarity than the first magnet is disposed within the upper recess; and a second magnet disposed within the lower recess, wherein no other magnet of a different polarity than the second magnet is disposed within the lower recess, wherein an air gap exists between the first magnet and the second magnet, wherein an opening in the soft magnetic material member is sized to accommodate at least a portion of the magnetic recording disk between the first magnet and the second magnet, wherein the magnetic field produced by both the first magnet and the second magnet flows (a) in the same direction, and (b) perpendicular to the plane of the magnetic recording disk, and wherein the strength of the magnetic field produced by the apparatus at a position at which a motor of a hard-disk drive is located when the hard-disk drive is disposed within the opening is at most a quarter of the strength of the magnetic field at the magnetic recording disk of the hard disk drive.