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Browse Prior Art Database

Slant Servo Pattern and Writing Method for Hard Disk Device

IP.com Disclosure Number: IPCOM000119132D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 90K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR [+3]

Abstract

Disclosed is a sector servo pattern magnetically written on the disk surfaces in a Hard Disk Drive (HDD) and the servo writing method. The servo pattern consists of optional cylinder Identifications (IDs) and burst signals written in slant to the track direction (Fig. 1). When the magnetic head reads the servo pattern, the amplitude of the read signal wave form gets wedge shape modulation. The phase of the wedge envelope is very dependent of the head position (Figs. 2 and 3). Then, the head position can be detected, referring the cylinder ID and the phase as the distance from the track center. The cylinder ID and sync pattern are written parallel to the track direction. However, the burst pattern is written with swinging the actuator accurately following the sine locus.

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Slant Servo Pattern and Writing Method for Hard Disk Device

      Disclosed is a sector servo pattern magnetically written on
the disk surfaces in a Hard Disk Drive (HDD) and the servo writing
method.  The servo pattern consists of optional cylinder
Identifications (IDs) and burst signals written in slant to the track
direction (Fig. 1).  When the magnetic head reads the servo pattern,
the amplitude  of the read signal wave form gets wedge shape
modulation.  The phase of  the wedge envelope is very dependent of
the head position (Figs. 2 and  3).  Then, the head position can be
detected, referring the cylinder ID  and the phase as the distance
from the track center.  The cylinder ID and  sync pattern are written
parallel to the track direction.  However, the  burst pattern is
written with swinging the actuator accurately following  the sine
locus.  The sine wave form is almost linear around every half
period.  Then, the pseudo linear slant burst can be written at every
half period of the sine locus.  The servo pattern is continuous over
the tracks so that the Position Error Signal (PES) is very linear,
avoiding the frigidity problem which a conventional servo pattern has
across the  adjacent tracks.  A conventional HDD servo system refers
two bursts with  left and right edges of the Magneto Resistive (MR)
head.  Then, the asymmetry of MR amplitude at both sides makes PES
linearity worse.  However, the proposed PES collection system refers
a single burst  at one side of the edge so that there is no influence
of the asymmetry  problem.  This method gives the above merits
without big issue to the equipment for servo writing.

      This method allows the servo track pitch to be equivalent to
the data track pitch.  However, the servo track pitch ideally depends
on the write head width, which is narrower than the data track pitch.
In this case, the servo track pitch and d...