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Magnetic Head Training Algorithm to Suppress Peak Shift

IP.com Disclosure Number: IPCOM000100748D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 31K

Publishing Venue

IBM

Related People

Kurachi, K: AUTHOR [+3]

Abstract

An algorithm which suppress the peak shift of a read back signal is described. This algorithm is based on a theoretical analysis of the read back signal distortion due to the electromagnetic characteristics of a head. This algorithm leads approximately 10% area density improvement.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Magnetic Head Training Algorithm to Suppress Peak Shift

       An algorithm which suppress the peak shift of a read back
signal is described.  This algorithm is based on a theoretical
analysis of the read back signal distortion due to the
electromagnetic characteristics of a head.  This algorithm leads
approximately 10% area density improvement.

      Generally there is about 10 to 20 ns peak shift. According to
the theoretical analysis, it was found out that the phenomenon was
caused by unnecessary magnetization of magnetic heads.  This peak
shift (signal distortion) makes the error rate higher and lowers the
performance of hard disk drive.

      In order to suppress this kind of signal peak shift, it is
necessary to demagnetize the head material itself.  This newly
developed algorithm eliminates the magnetization using 'AC ERASE'
technique.  Magnetization of magnetic materials can be demagnetized
(erased) by applying alternating magnetic field, and this is called
'AC ERASE'.  In this algorithm 'AC ERASE' is achieved by applying
decreasing AC current to a head coil.

      The algorithm is as follows:
      1. Write sectors.
      2. After every writing, 'AC ERASE' operation is done at
   sector gap areas, and wait for reading operation is to be
   done next.
      3. Read sectors.

      By using this method, most of signal peak shift can be
eliminated.