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Track-Pitch Measurement of Low End DASD Product

IP.com Disclosure Number: IPCOM000114408D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Hisano, T: AUTHOR [+3]

Abstract

This article describes Track-Pitch Measurement of Hard Disk Drive (HDD) product which was written by Servo Track Writer (STW). After writing by STW, nobody knows how accurately STW writes servo pattern on the HDD, so without giving any damage to the file, this method measures track pitch from starting cylinder to last cylinder of the HDD file required.

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Track-Pitch Measurement of Low End DASD Product

      This article describes Track-Pitch Measurement of Hard Disk
Drive (HDD) product which was written by Servo Track Writer (STW).
After writing by STW, nobody knows how accurately STW writes servo
pattern on the HDD, so without giving any damage to the file, this
method measures track pitch from starting cylinder to last cylinder
of the HDD file required.

      Fig. 1 shows how to measure track pitch using rotary
positioner.  Track Pitch (TP) device pushes the carriage of HDD to
increment the head every 1/8 track at least with rotary positioner
and gets Position Error Signal (PES) every 1/8 track through
production card attached HDD file.  After moving one track, TP device
gets 8 PES and searches two PES, which are both pointers of track
center (PES 128) in Fig. 2, therefore TP device gets track center p0
from this formula-1 and subsequently find another track center using
same method no matter how many cyliders HDD has.

After gathering those data through cylinders passed, TP device gets
track pitch as follows:
  p0(N+1) - p0(N)
  N: tarck #
  And TP device gets the number of track pitch required.

This method is effective to measure track pitch, regardless of HDD
size and capacity.