Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Effective Demagnetization of Top Clamp for HDD Disk Eraser

IP.com Disclosure Number: IPCOM000123720D
Original Publication Date: 1999-Apr-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 4 page(s) / 116K

Publishing Venue

IBM

Related People

Ohta, M: AUTHOR [+2]

Abstract

This article describes a method of effective demagnetization of Top Clamp(*1) made of magnetism material for Hard Disk Drive (HDD) at disk erase process.

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

Effective Demagnetization of Top Clamp for HDD Disk Eraser

   This article describes a method of effective
demagnetization of Top Clamp(*1) made of magnetism material for Hard
Disk Drive (HDD) at disk erase process.

   At disk erase process of HDD salvage process, HDD enters
to the magnet field ,that is disk eraser magnet gap of "Disk
Eraser"(*2), more than disk magnetic coercive force, therefore,
without disassemble can erase servo pattern data and recorded data
etc. by rotating disk.  To erase data on disk, the magnetic field
needs to be formed to disk circumference direction(*3).  Top clamp
made of magnetism material is magnetized by magnetic leakage flux
density of the disk eraser.(Fig.1)

   As HDD is pushed to or pulled out from disk eraser magnet
gap in rotating disk, magnetized top clamp is effective on AC
demagnetize.  More slowly pullout and constant speed, more
demagnetize.  The effect is confirmed by following experiment.

   Before processing Disk Erase, Top clamp made of SUS420J2
is magnetized.  After Disk Erase Process on changing pullout speed,
Br of Top clamp outer is measured.  From this result, More slowly
pullout, more demagnetize can be found.  (Fig.2)