Browse Prior Art Database

Voice Coil Motor Retract Current Off Scheme After a Predetermined Time

IP.com Disclosure Number: IPCOM000119134D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Arai, K: AUTHOR [+4]

Abstract

Disclosed is a Voice Coil Motor (VCM) used in a Hard Disk Drive (HDD) which retracts the current shut off scheme to suppress the retract noisy sound of an HDD after power off.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 93% of the total text.

Voice Coil Motor Retract Current Off Scheme After a Predetermined Time

      Disclosed is a Voice Coil Motor (VCM) used in a Hard Disk Drive
(HDD) which retracts the current shut off scheme to suppress the
retract noisy sound of an HDD after power off.

      The merit of this disclosure is that it provides the method to
shut off the VCM retract current at a predetermined time after power
off and suppress the noisy sound which is generated during retract
current flow.  The Figure shows how to realize this scheme.

      The retract current is a half rectified current which can
generate the noisy sound from an HDD.  The retract current through
the VCM is supplied from one phase of spindle Back Electro Motive
Force (EMF).  This current flow goes through R1 and FET down to VCM
coil. When  the supply voltage exists, the gate of FET is fed plus
voltage by 5V HDD  supply and 12V, and FET stays conductive.  (Not
affecting normal HDD operation since back EMF is not supplied from
spindle because of the driver chip function.)  When either of 5V or
12V power off occurs, the  D1 will not feed any charge into C1,
resulting in the decay of the voltage across C1.  The decay of the
voltage results in the drop of the  FET gate voltage and the retract
current through FET is pinched with the predetermined time
constraint, which can be decided by C1 and R2 constant.  Thus, at the
predetermined time decided by C1 and R2 after  power off, FET starts
to pinch the VCM retra...