Browse Prior Art Database

Fast Offset Recovery for Thermal Asperity Data Recovery Procedure

IP.com Disclosure Number: IPCOM000108038D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 115K

Publishing Venue

IBM

Related People

Kerwin, GJ: AUTHOR [+3]

Abstract

Herein disclosed is a method of reducing the corruption, due to a thermal asperity (TA), of the readback signal of a magnetic recording disk drive which uses a magneto-resistive (MR) head. This technique is only used during a re-read step of the drive's data recovery procedure when a thermal asperity event is suspected.

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This is the abbreviated version, containing approximately 60% of the total text.

Fast Offset Recovery for Thermal Asperity Data Recovery Procedure

       Herein disclosed is a method of reducing the corruption,
due to a thermal asperity (TA), of the readback signal of a magnetic
recording disk drive which uses a magneto-resistive (MR) head.  This
technique is only used during a re-read step of the drive's data
recovery procedure when a thermal asperity event is suspected.

      The employment of the frequency-response-modifying circuit when
read data has been corrupted by a thermal asperity, in concert with
error-correcting code (ECC), can greatly increase the probability of
recovery.  The error-burst length is reduced to where the ECC can
correct the data, thus avoiding an error event.  The technique
involves activating circuitry which effectively raises the frequency
response of the direct-current (DC) coupling pole in the arm
electronics (AE).  This allows any sudden change in the DC value or
offset to be restored sooner.  The frequency response in this TA
recovery mode would degrade the soft error rate if not switched back
after the data recovery step is complete.  Fig. 1 shows a typical
modulation of the readback signal when the magneto-resistive element
comes in contact with a mechanical defect on a disk. The amplitude of
the DC shift is determined by the temperature rise of the element,
and the time constant is determined by the frequency response of the
DC-cancelling operational transconductance amplifier (OTA). If the
frequency...