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Shunt Flux Active Magnetic Latch for Portable Disk Drive Systems

IP.com Disclosure Number: IPCOM000117847D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Albrecht, DW: AUTHOR [+2]

Abstract

In contact start/stop disk drive systems, such as portable disk drive systems, reliability is enhanced if the recording head never leaves the start/stop zone during the power off state even under external shock. Such portable disk drive systems must withstand shock of greater than 50 K rad/sec2 radial acceleration. In addition, power consumption in these portable systems must be kept to a minimum.

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Shunt Flux Active Magnetic Latch for Portable Disk Drive Systems

      In contact start/stop disk drive systems, such as portable disk
drive systems, reliability is enhanced if the recording head never
leaves the start/stop zone during the power off state even under
external shock.  Such portable disk drive systems must withstand
shock of greater than 50 K rad/sec2 radial acceleration.  In
addition, power consumption in these portable systems must be kept to
a minimum.

      Previously, series type active magnetic latches were proposed.
However, to provide a large holding force, a large bucking current to
release the actuator was also required.

      In the shunt active magnetic latch design, this inherent
problem is overcome.  The holding force and bucking current can be
optimized separately.  Thus, this latch design allows very large
holding force, and also enable efficient use of the systems power
(current).  The Figure shows the flux shunt latch design.

      The shim is a magnetic piece which is connected to the
actuator.  In the latched state as shown, the flux from the hard
magnet holds the actuator in place and only a small amount of flux
flows throughout the control gap at the back end of the yoke.  To
release the latch, the coil is energized to shunt the flux from the
actuator throughout the control gap, thereby releasing the actuator.
The reluctance of the control gap can be made very small to provide
the efficient magnetic circuit, prov...