Masahiro Mita

54953766, Feb 27, 1996

Jun 29, 1994

8/267307

Ken G. Wasson - Foster City CA
Masahiro Mita - Chula Vista CA
Juro Endo - Chula Vista CA

Hitachi Metals, Ltd. - Tokyo

G11B 554

360105

A latch mechanism, especially for use in a disk drive, includes a locking arm that rotates about a pivot and engages a slot on the moving member that is to be locked, such as a head-arm. In a fixed coil embodiment, a permanent magnet is attached to an inboard end of the locking arm within the windings of a coil. Ferrous elements are mounted between the coil and the pivot of the locking arm. The ferrous elements attract the permanent magnet to hold the locking arm securely in either a latching or an unlatching state. When the coil is energized, poles are induced in the ferrous elements such that one repels the permanent magnet away from its then current state into the opposite state, while the other ferrous element attracts the permanent magnet to the other state. The magnetic field of the coil simultaneously applies a pure torque to the locking arm. This torque rotates the locking arm so that the arm changes to its other state.

55239110, Jun 4, 1996

Oct 25, 1993

8/143531

Masahiro Mita - Chula Vista CA
Juro Endo - Chula Vista CA
Ken G. Wasson - Foster City CA

Hitachi Metals, Ltd. - Tokyo

G11B 555

360106

A head positioning system for a magnetic disk drive includes an actuator arm that is mounted on a pivot bearing so that the axis of rotation of the arm passes through the center of mass of the arm. A Faraday-type motor using a single coil applies a force couple to the arm at a location offset from the center of mass of the arm with a constant moment arm. The offset force couple creates a pure torque about the axis of rotation of the arm (that is, about the pivot bearing) in order to substantially eliminate reaction forces on the bearing; this greatly lessens wear on the bearing and in turn reduces the non-repeatable run-out error of the read/write head mounted at the end of the arm. Various arrangements of permanent magnets and motor windings are provided to create the force couple. Furthermore, in certain embodiments, yokes are included to increase the magnetic field strength of the motor, thus increasing its power and reducing magnetic leakage and the risk of disturbing the data stored in the magnetic disk medium.