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Browse Prior Art Database

Self Optimization for Precompensation Cylinder

IP.com Disclosure Number: IPCOM000122480D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Kosuge, O: AUTHOR [+3]

Abstract

Disclosed is a YIELD improvement technique for HDD (Hard Disk Drive). HDD has several Read/Write heads. Final shipment test "Pass or Fail" highly depends on the worst performance head. So improvement of the worst head performance is important for production YIELDs.

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This is the abbreviated version, containing approximately 69% of the total text.

Self Optimization for Precompensation Cylinder

      Disclosed is a YIELD improvement technique for HDD (Hard
Disk Drive).  HDD has several Read/Write heads. Final shipment test
"Pass or Fail" highly depends on the worst performance head. So
improvement of the worst head performance is important for production
YIELDs.

      A good HDD can read written data correctly for any time. But if
the Precompensation Cylinder is not optimum, SER (Soft Error Rate)
and HER (Hard Error Rate) become high. (The Precompensation Cylinder
is a starting cylinder from which a writing precompensation is made.)
In this situation, the possibility that HDD can not read written data
correctly is high.  So the Precompensation Cylinder is important for
HDD SER and HER.
      1) Optimum Precompensation Cylinder highly depends on
         Head/Disk combination.
         Some Precompensation Cylinder is optimum for some
         Head/Disk combinations.
         But it is not optimum for other Head/Disk
         combinations.
         HDD has several Head/Disk combinations.
         So final shipment test "Pass or Fail" depends on
         the worst Head/Disk combination.
         HDD is judged "Fail" even if there is only one worst
         combination.
      2) General Optimization (see figure)
         - Measure SER by writing with precompensation "on"
         and then reading.
    ...