Browse Prior Art Database

Low Rotational Speed Disk Surface Analysis for Thermal Asperity by Direct Current Erase Between Servo

IP.com Disclosure Number: IPCOM000117332D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Matsui, T: AUTHOR [+8]

Abstract

This article describes the disk surface analysis method which increases detectability of extra peak signal by Thermal Asperity (TA) on the disk by reading DC-erased data area between servo at lower RPM on Hard Disk Drive (HDD) unit with Magneto Resistive (MR) head.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 94% of the total text.

Low Rotational Speed Disk Surface Analysis for Thermal Asperity by
Direct Current Erase Between Servo

      This article describes the disk surface analysis method which
increases detectability of extra peak signal by Thermal Asperity (TA)
on the disk by reading DC-erased data area between servo at lower RPM
on Hard Disk Drive (HDD) unit with Magneto Resistive (MR) head.

      At test track, encoder of write channel circuit is bypassed to
do DC erase with all "0" data, on all synchronization area (SYNC)
Address Mark (AM) and data/ECC area which lies between write recovery
/servo area of gray code and of wedge burst signal.

      After Direct Current (DC) erase on test area, extra peak search
in erased area by monitoring peak detector digital output of read
channel is done to inform location that has thermal asperity
possibility to Hard  Disk Controller (HDC).

      If HDC receives detection signal from channel, HDC calculates
actual sector location where user data read/write is prohibited.

      During peak search operation, drive rotational speed (RPM) is
decreased to make head slider flies lower than nominal fly height for
harder contact between disk asperity and head element, and that
accelerates thermal disturbance.

      Detection level can be adjusted by RPM, detection threshold
level and by others, in peak search operation.

      After one track is tested, sequence of DC-erase and peak search
at lower RPM is repeated until whole sur...