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Potential Thermal Asperity Screening

IP.com Disclosure Number: IPCOM000117330D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Kisaka, M: AUTHOR [+4]

Abstract

In the application of Hard Disk Drive (HDD) which uses Magneto Registive (MR) head, the creation of Thermal Asperity (TA) and the lower Fly Height (FH) is the trade off each other.

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

Potential Thermal Asperity Screening

      In the application of Hard Disk Drive (HDD) which uses Magneto
Registive (MR) head, the creation of Thermal Asperity (TA) and the
lower Fly Height (FH) is the trade off each other.

      Recent HDD has very low FH to achieve the high recording
density, which makes the possibility of TA high than it used to be.

This invention is the effective method to screen out the potential
TAs at the worst case.

      In order to detect the potential TAs, this method can creates
the extreme condition for the TA generation.  And under the extreme
condition, TAs are found effectively.  This method achieve this
extreme condition by changing the disk rotational speed.
  1.  Servo Lock to the Various Disk Speed
        Servo Data is embedded on disk, thus servo data frequency
       changes as the disk speed varies.  In order to lock to the
       variable frequency of the servo data (Gray Code), controller
       which detect the servo data, variable speed of clock is feed
into
       the controller.  This clock is provided by the synthesizer of
R/W
       channel.
  2.  Detection of TA
        The next step is to find the TA location by reading the
       written data.  In the slow rotaion condition, only peak
detector
       of the R/W channel can be used because VFO can not capture
such a
       different frequency.  So it is necessary to detect TAs only
using
 ...