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Method of Servo Pattern Writing for Hard Disk Drive without Erase Band

IP.com Disclosure Number: IPCOM000112476D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 66K

Publishing Venue

IBM

Related People

Iwata, K: AUTHOR [+3]

Abstract

Disclosed is a method of servo track writing on Hard Disk Drives (HDDs), which does not make erase bands in servo pattern. The method prevents undesirable effect caused by the erase band and realizes higher track pitch.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Method of Servo Pattern Writing for Hard Disk Drive without Erase Band

      Disclosed is a method of servo track writing on Hard Disk
Drives (HDDs), which does not make erase bands in servo pattern.  The
method prevents undesirable effect caused by the erase band and
realizes higher track pitch.

      Fig. 1 shows a typical servo pattern that consists of
synchronous pattern (1), burst-A (2) and burst-B (3).  A center of
track (4) is determined as a point where amplitudes of read back
signals of burst A and burst B become equal to each other.  A servo
writer writes such servo pattern by means of overwriting pattern-A
(5) and pattern-B (6) alternately (Fig. 2).  An excess write
characteristic of data heads, however, makes erase band (7) where no
effective servo pattern is recorded (Fig. 3).  This erase band
increases servo gain of head positioning system, which is considered
as a bottle neck to achieve higher track pitch.

      The method disclosed in this article uses two control signal
patterns, control pattern-1 (8) and control pattern-2 (9), together
with pattern A and pattern B (Fig. 4).  Two control patterns are used
to switch AE module of the hard disk between read and write modes.
Suppose low level of signals turns AE module to write mode.  This
method writes servo pattern in the following sequence in order to
avoid erase bands (Fig. 5).  First, write pattern-A (5) as usual.
Second, move a recording head (10) by half of the track pitch and
write...