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Drive Method for Torque-Up of Sensorless Motor

IP.com Disclosure Number: IPCOM000101119D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 78K

Publishing Venue

IBM

Related People

Lee, S: AUTHOR [+2]

Abstract

Disclosed is a technique for getting a torque amplification (5 - 7 times) at start-up of a sensorless spindle motor of a hard disk drive (HDD). This technique is particularly useful for the small HDD with the small sensorless spindle motor.

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Drive Method for Torque-Up of Sensorless Motor

       Disclosed is a technique for getting a torque
amplification (5 - 7 times) at start-up of a sensorless spindle motor
of a hard disk drive (HDD).  This technique is particularly useful
for the small HDD with the small sensorless spindle motor.

      The technique will be well understood with reference to Fig. 1
which schematically shows the typical HDD.  The HDD shown in Fig. 1
comprises a sensorless spindle motor 1, a head 2, a flexure 3, a
suspension 4, an arm 5, a disk 6, etc.  The state that the head 2
is stuck on the disk 6 occurs in a certain environmental condition.
Then a large start-up torque is required for starting up the spindle
motor in this stuck state.  Supplying the spindle motor with such
large torque is quite difficult in a small HDD.

      To solve this problem, a technique was developed to amplify a
motor torque utilizing resonant energy of disk-rotor mass and head
longitudinal compliance.

      The essence of this technique is to give a vibrational torque
to the resonant components by driving the sensorless spindle motor 1
with resonant frequency.  But because this resonant frequency varies
with the device or the number of stuck heads, frequency scanning is
required.

      Two new methods of vibrating the sensorless spindle motor are
proposed.  The first method is to switch a coil current on and off by
control of a voltage supplied to a drive transistor.  The other
metho...