Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Providing Magnetic Force for Head Unload Ramp

IP.com Disclosure Number: IPCOM000117350D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Cunningham, EA: AUTHOR

Abstract

A method is disclosed that produces magnetic forces parametrically to help push recording head suspensions up a ramp to unload the heads from the disk. With this method, the forces on the actuator can be minimized when the head is in the data zone, and can be designed with significant freedom of the shape of force versus distance up the ramp.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Providing Magnetic Force for Head Unload Ramp

      A method is disclosed that produces magnetic forces
parametrically to help push recording head suspensions up a ramp to
unload the heads from the disk.  With this method, the forces on the
actuator can be minimized when the head is in the data zone, and can
be designed with significant freedom of the shape of force versus
distance up the ramp.

      In the smaller form factor hard disk drives used in battery
operated portable computer systems, it is common to have a
load/unload system for the heads.  When unloaded, the heads do not
add drag to the start motor and the start time is not as critical
when the heads do not have to be flown off the disk in a short time
to minimize sliding wear.  This reduces the power and torque
requirements of the motor.  The resulting smaller motor also reduces
the capability to use the motor as a generator during power shut
down, which is normally used in larger disk drives, to retract the
actuator.  In the load/unload case, the retract must not only move
the actuator and heads to the parking zone, but must provide
additional force to slide the lifting tabs on the suspensions up a
ramp to unload the heads from the disk.  Thus, it is desirable to
provide some or all of the required unloading force by some other
means than the normal method of obtaining actuator current after a
power down by rectifying the back-EMF from the motor.  During head
unload without power down, the extra force from another source will
also reduce the maximum current required to park the heads.

      This disclosed method uses parametrically generated force in a
manner similar to a solenoid, where a soft magnetic core is pulled
into the higher energy magnetic field region.  The force in this case
is calculated by the virtual work approach, by taking the distance
rate of change of stored energy.  The high energy magnetic field is
obtained using permanent magnets and pole structures, which can be
part of the magnets and poles of the normal actuator system.  The
core can initially be considered as a small iron rectangular solid,
attached to the back end of the actuator which normally holds the
actuator coil.

      The core enters a slot that has the high energy magnetic field
perpendicular to the direction of motion.  If the length of the core
and the slot are comparable, there will be a very low force when the
core is outside the slot, but then the force becomes approximately
uniform as the core moves into the slot....