Browse Prior Art Database

Methods to Self Servowrite Disk Drives with Load/Unload Ramps

IP.com Disclosure Number: IPCOM000117949D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Chainer, TJ: AUTHOR [+6]

Abstract

Methods of disk drive servowriting, known as self-servowrite, have been previously described (*). These methods are based on the presence of crash stops demarcating the Inner Diameter (ID) and Outer Diameter (OD) boundaries of the disk(s) to begin and end the self-servowrite process.

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Methods to Self Servowrite Disk Drives with Load/Unload Ramps

      Methods of disk drive servowriting, known as self-servowrite,
have been previously described (*).  These methods are based on the
presence of crash stops demarcating the Inner Diameter (ID) and Outer
Diameter (OD) boundaries of the disk(s) to begin and end the
self-servowrite process.

      Some modern disk files employ load/unload ramps at one end of
the disk medium.  In the case of servowriting from the disk OD, the
self-servowrite process begins from the load/unload ramp or
alternatively, when starting at the ID, the process ends against the
ramp.  Several methods are described to detect the load/unload ramp.

Method 1 - Ramp with change in slope

      As shown in the Figure, a load/unload ramp is designed with a
change in slope such that the loading ramp can be detected.  This can
be accomplished by first unloading the heads from the ramp, then
reversing the current and moving the head towards the OD until the
head suspension makes contact with the steep section of the ramp.

Method 2 - Detecting increase in DC control current

      The contact of the arm with the ramp can be detected by
propagating radial magnetic patterns from the ID to the OD, and
observing an increase in the VCM control current, indicating contact
with the ramp.

Method 3 - Detecting change in TMR

      Subsequent to unloading the heads, the VCM control current can
be reversed to move the actuator towards the OD.  A magnetic track
can be written and used to measure head to trac...