Browse Prior Art Database

Write-Wide, Read-Narrow Vertical Recording Head

IP.com Disclosure Number: IPCOM000100144D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 107K

Publishing Venue

IBM

Related People

Seagle, DJ: AUTHOR

Abstract

In a conventional magnetic recording system in which the same head is used to perform both the read and write functions, areal density is limited by the effects of track misregistration. Data retrieved during a read operation is hindered by remnants of previously written old information at the edges of the track when the head is mispositioned with respect to the position in which the track was written. In longitudinal recording the effect is somewhat limited in that an 'erase band' is set up at the edge of the track which partially erases the old information in bands on both sides of the track. Thus, a higher track density is supportable for a given level of track misregistration. In vertical recording, however, an extremely sharp track profile is written when a soft ferromagnetic underlayer is used.

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Write-Wide, Read-Narrow Vertical Recording Head

       In a conventional magnetic recording system in which the
same head is used to perform both the read and write functions, areal
density is limited by the effects of track misregistration.  Data
retrieved during a read operation is hindered by remnants of
previously written old information at the edges of the track when the
head is mispositioned with respect to the position in which the track
was written. In longitudinal recording the effect is somewhat limited
in that an 'erase band' is set up at the edge of the track which
partially erases the old information in bands on both sides of the
track.  Thus, a higher track density is supportable for a given level
of track misregistration. In vertical recording, however, an
extremely sharp track profile is written when a soft ferromagnetic
underlayer is used.  Little to no erase band is typically observed
and the maximum areal density is significantly diminished by the low
track density requirements.

      A better technology than erase bands is found in a write-wide,
read-narrow head.  The effective write width of the head needs to
exceed the read width by at least the maximum track misregistration
to assure that no old information interferes.  In this disclosure a
write-wide read-narrow vertical recording head is described that
works with a double layer vertical recording medium.  Such a head
provides three basic advantages; only one head is required to perform
both read and write functions, it writes wide and reads narrow, and
it allows some independence in designing the read and write
processes.  This last attribute is a significant improvement over
conventional single head recording but falls short of the extreme
independence of the more complicated two head schemes.

      The above can be accomplished by means of extending the
conventional single pole head with return flux pole into a three-pole
head which has the following attributes:
1) A single thin pole acting as a read pole.
2) A thick pole wider than the first to act as both a write pole
and a return flux pole for the read operation.
3) A third pole to act as a return flux pole for the write operation.
4) Poles 1 and 3 are coupled to pole 1 through one coil.

      A possible configuration is shown in the accompanying figure.

      The write process i...