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Disk Magnetic Test With Effective Highest Frequency

IP.com Disclosure Number: IPCOM000100764D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Kurachi, K: AUTHOR [+3]

Abstract

Disclosed is a modified method to evaluate magnetic recording characteristics of heads/disks used in hard disk drives. The purpose is to get a good correlation on the sample characterization between the single head/disk parametric test and the read error rate test. (The single head/disk parametric test refers to a component-level head/disk characterization by its HI-F amplitude, resolution, etc.) This cor relation means that a statistical dispersion and relative superiority/ inferiority of the samples' quality is consistent between these two tests. A key parameter for a good correlation is the minimum magnet length written on a disk. Thus, the minimum magnet lengths of these tests should be equal.

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Disk Magnetic Test With Effective Highest Frequency

       Disclosed is a modified method to evaluate magnetic
recording characteristics of heads/disks used in hard disk drives.
The purpose is to get a good correlation on the sample
characterization between the single head/disk parametric test and the
read error rate test.  (The single head/disk parametric test refers
to a component-level head/disk characterization by its HI-F
amplitude, resolution, etc.) This cor relation means that a
statistical dispersion and relative superiority/ inferiority of the
samples' quality is consistent between these two tests.  A key
parameter for a good correlation is the minimum magnet length written
on a disk.  Thus, the minimum magnet lengths of these tests should be
equal.  The proposed method is to set a write frequency (in the
single head/disk test) higher than the nominal highest frequency by
the amount of nonlinear bit-shift.  This write frequency is called
the effective highest frequency.

      The error rate test uses a random pattern as write data. The
single head/disk test, however, uses the highest frequency pattern.
Compared with these two tests, the minimum magnet length of the
former is shorter than that of the latter by the nonlinear bit-shift
shown in the figure.

      The test procedure is as follows:
      (1) Measure the amount of nonlinear bit-shift with typical
head/ disk combination using a random pattern.
      (2) Calculate the effective...