Browse Prior Art Database

Two-Burst Direct Access Storage Device Servo Pattern

IP.com Disclosure Number: IPCOM000118068D
Original Publication Date: 1996-Sep-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 104K

Publishing Venue

IBM

Related People

Stephenson, JJ: AUTHOR

Abstract

Disclosed is a servo pattern that contains two quad burst position error fields instead of the conventional four. It delivers the same +/- 1 track measurement range that is used today, thus saving 50 percent of the disk space needed for the servo pattern but achieves the same result.

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Two-Burst Direct Access Storage Device Servo Pattern

      Disclosed is a servo pattern that contains two quad burst
position error fields instead of the conventional four.  It delivers
the same +/- 1 track measurement range that is used today, thus
saving 50 percent of the disk space needed for the servo pattern but
achieves the same result.

      The Figure shows the burst layout that's being proposed for
this invention.  The vertical line made of $ signs represents a
one-track wide head (this is usually a thin film inductive head) and
the @ signs  represents a .5 track wide head (this is usually an MR
head).  The horizontal edges of the burst fields are designated as
A1, A2, B1, and  B2.  The track centerlines are shown as Track n-2,
n-1, etc..  The radial  spacing for each burst is 1/2 track of
separation.  The Automatic Gain  Control (AGC) field is assumed to be
written from the Outer Diameter (OD) to the Inner Diameter (ID) in a
phase-aligned fashion at the same  frequency as the A and B burst
fields are written.  A gray code is written on each track in a phase
aligned fashion.
         OD
                                             1
  Track n-2 ---|----|--|        |-------===========--------------
               |    |  |        |       |         |      1
               |    |  |        |       |    A    | ===========
               |    |  |        |       |         | |         |
  Track n-1 ---|----|--|        |-------===========-|    B    |--
               |Gray|  |  AGC   |            2      |         |
               |Code|  | FIELD  |  $                ===========
               |    |  |        |  $ @       1           2
  Track n   ---|----|--|        |--$-@--===========--------------
               |    |  |        |  $ @  |         |      1
               |    |  |        |  $    |    A    | ===========
               |    |  |        |       |         | |         |
  Track n+1 ---|----|--|        |-------===========-|    B    |--
                                             2      |         |
     ID                                             ===========
                                                         2
                                  Figure

      The position is obtained by measuring the amplitude or area of
the signal seen by the head a...