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Data on a Magnetic Recording Disk

IP.com Disclosure Number: IPCOM000107144D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 3 page(s) / 89K

Publishing Venue

IBM

Related People

Palmer, DC: AUTHOR

Abstract

Using photolithographic techniques, servo data and other header information that is usually written track by track with a servowriter can be deposited on the disk surface during the fabrication of the disk. A large external magnetic recording head aligns the magnetization in each of the magnetic layers, a process which is faster than the bit-by-bit recording process currently used. Multiple layers with differing coercivities allow for a full magnetization reversal at each transition.

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Data on a Magnetic Recording Disk

       Using photolithographic techniques, servo data and other
header information that is usually written track by track with a
servowriter can be deposited on the disk surface during the
fabrication of the disk.  A large external magnetic recording head
aligns the magnetization in each of the magnetic layers, a process
which is faster than the bit-by-bit recording process currently used.
Multiple layers with differing coercivities allow for a full
magnetization reversal at each transition.

      Current discrete magnetic tracks are patterned by
photolithography so that the magnetic layer is a series of concentric
rings, but are continuous along the track.  This invention extends
this idea to include patterns along the track, using single and
multiple magnetic layers, so that prewritten data, such as servo data
or header information, can be added to a disk at the time of the disk
fabrication.

      In the simplest implementation a single layer of hard magnetic
material is deposited on the disk surface as shown in Fig. 1.  The
pattern along the track consists of lengths of magnetic material
separated by gaps of no magnetic material.

      The media is then initialized by DC-erasing with a field in the
plane of the disk.  The source of the horizontal field could be a
large external magnet or electromagnet, a multi-track flying head, or
a single-track flying head.  The magnetization along the track then
appears as in Fig. 1, which shows the magnetization in the servo
track A.  The magnetization changes are defined by the edges of the
magnetic material, and these correspond to the purely magnetic
transitions that occur in...