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High Frequency Decoupling on Voice Coil Motor Line for Read Error Rate of Hard Disk Drive

IP.com Disclosure Number: IPCOM000118862D
Original Publication Date: 1997-Aug-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Amano, Y: AUTHOR [+3]

Abstract

Disclosed is a method to protect read error rate from degradation caused by noise on Voice Coil Motor (VCM) driving lines. Adding a proper component as a filter on the way of the VCM line protects the head raw signal from the noise.

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

High Frequency Decoupling on Voice Coil Motor Line for Read Error
Rate of Hard Disk Drive

      Disclosed is a method to protect read error rate from
degradation caused by noise on Voice Coil Motor (VCM) driving lines.
Adding a proper component as a filter on the way of the VCM line
protects the head raw signal from the noise.

      The Figure shows configuration of a Hard Disk Drive (HDD) on
the VCM and the head signal.  The VCM line starts from a VCM driver
module on a control card, and goes through a flexible cable in a disk
enclosure and ends at the VCM.  The VCM line is parallel to a head
signal line on the flexible cable.  The distance between the lines
tends to decrease as a tiny HDD is developed.  Then the noise on the
VCM line becomes a issue on the read error rate degradation.

      The high-frequency noise is originally produced at various
Large Scale Integration (LSI) and driver modules on the control card
and goes out through signal, power, or grounding lines.  Then the
noise couples on the VCM line and disturbs the head raw signal.
Adding a proper component as a filter on the way of the VCM line
protects the head  signal from the noise.

Some effective filters are shown as the following:
  Non-insulation type:
    a.  Ferrite inductor
    b.  Capacitor
    c.  Combination of a. and b.
  Insulation type:
    d.  Use of an isolation amplifier like Photo coupler