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Magnetoresistive Head Switch Time Reduction using Correlated Tolerances

IP.com Disclosure Number: IPCOM000110986D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Coker, JD: AUTHOR [+3]

Abstract

Disclosed is a method that makes use of the correlation of the offset of write and read elements for Magnetoresistive (MR) heads on a wafer, to reduce the relative offset between heads within a Direct Access Storage Device (DASD) unit, thus reducing the head switch times in reading through the heads in each data cylinder.

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Magnetoresistive Head Switch Time Reduction using Correlated Tolerances

      Disclosed is a method that makes use of the correlation of the
offset of write and read elements for Magnetoresistive (MR) heads on
a wafer, to reduce the relative offset between heads within a Direct
Access Storage Device (DASD) unit, thus reducing the head switch
times in reading through the heads in each data cylinder.

      In manufacturing MR read/write heads, the read and write
elements are defined by different mask sets.  Thus, there is some
offset error between the desired position of the read element
relative to the write element.  In addition, the magnetic center of
the read element differs somewhat from the physical center, and this
amount may be slightly different for different wafers.  However,
there is a significant correlation of these offsets over a given
wafer of heads.

      With the proper design of the heads on a wafer, and in using
all heads in one DASD unit from one wafer, the correlation can reduce
the amount of change in off-track positioning required in switching
from one head to the next, in the process of reading data from a
cylinder of tracks.  This can reduce the settle time in switching
from one head to the next, due to the smaller compensation distance
required.  The reduced difference between heads can also be used to
good advantage in the construction of DASD containing multiple heads
reading out data through multiple data channels at the same time,
since one position of the actuator must be used for all the heads
being read in parallel.

      In order for all the heads in a...