Browse Prior Art Database

Disk Drive Tangential Offset Correction to Sector Pulse Placement

IP.com Disclosure Number: IPCOM000117460D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Donaldson, JE: AUTHOR [+2]

Abstract

Described is a method for periodic measurement and continuous compensation for tangential surface-to-surface offsets from a nominal location. The usefulness of which is an improvement in areal efficiency.

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This is the abbreviated version, containing approximately 52% of the total text.

Disk Drive Tangential Offset Correction to Sector Pulse Placement

      Described is a method for periodic measurement and continuous
compensation for tangential surface-to-surface offsets from a nominal
location.  The usefulness of which is an improvement in areal
efficiency.

      Data on hard disk drives is placed on cylindrical tracks.  The
actual location can vary from a nominal location in two dimensions.
These variations or offsets can be characterized into radial and
tangential components.

      The radial offset component can be resolved and compensated for
by the use of "Reference Track" techniques, which are common to
dedicated servo applications.  This technique cannot resolve or
compensate for tangential offsets.

      Typical to 'Dedicated Servo' or 'Embedded Servo' hard disk
drive applications, the dedicated and servo surface(s) contain
identifiable marks from which a differential timing measurement can
be made.  The requirement for suitable marking of the data surfaces
in a dedicated servo application can be achieved by using the same
disk marking as required for the Reference Track technique.  The
requirement for suitable marking in the embedded servo application
can be achieved by using the same disk markings as required for the
embedded servo technique.

      This tangential offset correction technique description assumes
that the timing marks on the servo surface(s) and on the dedicated
surface(s) are called "Servo Identification" marks or SID's.

      As shown in Fig. 1, the tangential offset of a customer data
record can be viewed as a  timing displacement from any other
surface, and in this case referenced to a single surface (surface 0).
Where time is on the horizontal axis and disk surfaces are on the
vertical axis.

      As shown in Fig. 2, the measurement of this offset can be
determined by the starting of a counte...