Browse Prior Art Database

Optimal Recording Head Performance Through Programmable Write Current

IP.com Disclosure Number: IPCOM000114131D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 85K

Publishing Venue

IBM

Related People

Chliwnyj, A: AUTHOR [+5]

Abstract

A technique is described whereby the as-written signal in the recording medium is tightly controlled through the use of write current levels tailored to each recording head module. The reason for this requirement is given, as well as a proposed embodiment for a practical recording system.

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Optimal Recording Head Performance Through Programmable Write Current

      A technique is described whereby the as-written signal in the
recording medium is tightly controlled through the use of write
current levels tailored to each recording head module.  The reason
for this requirement is given, as well as a proposed embodiment for a
practical recording system.

      Recording heads used in non-saturate type recording systems,
which include flexible media products that use tape or floppy disks,
typically have a range of performance parameters.  The most critical
performance attributes influenced by the recording (write) process
are overwrite and density (frequency) response, both of which are
functions of the combination of head and media characteristics.  In
an interchange environment, the system must be able to operate over a
range of head/media combinations such that data written on any media
can be read and overwritten by any drive system.

      There are several ways to maximize system performance, usually
involving a cost or yield penalty.  Heads can be specified more
tightly, resulting in losses at the manufacturing level.  Likewise,
media can be screened for specific properties.  The recording channel
can be tuned for each head using filtering and equalization but that
also has significant cost considerations and can get quite
complicated.

      A practical solution, which is discussed here, is to vary the
magnitude of the write current for each recording head.  This
technique not only minimizes the difference in density response among
heads, but also serves to maximize overwrite performance.

      Each head has a particular write saturation characteristic,
which determines the point where maximum readback amplitude is
achieved.  In practice, the best overwrite is obtained at a current
somewhat higher than the maximum amplitude so a trade-off is usually
made between those parameters.  The result is that the best operating
point usually occurs somewhere around 20...