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Method and Apparatus for Vertically Balancing an Actuator System for Improved Servo Performance

IP.com Disclosure Number: IPCOM000123595D
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 3 page(s) / 88K

Publishing Venue

IBM

Related People

Frees, G: AUTHOR [+2]

Abstract

Method and Apparatus for Vertically Balancing an Actuator System for Improved Servo Performance

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This is the abbreviated version, containing approximately 57% of the total text.

Method and Apparatus for Vertically Balancing an Actuator System
for Improved Servo Performance

   Method and Apparatus for Vertically Balancing an Actuator
System for Improved Servo Performance

   Disclosed is a method to improve the dynamics of a disk
drive actuator by vertically balancing the forces acting on the
actuator through the use of geometric and boundary condition (B.C.)
symmetry.  By balancing the forces acting on the actuator, we can
significantly reduce or eliminate the excitation of particular
vibration modes which degrade the settle performance of the
servo/mechanical system.

   The forces that act on the actuator during seek or
track-follow servo control are: a.) the force in the coil 10 when
current is applied to coil, and b.), the reaction forces in the ball
bearings 11, 12 of the pivot cartridge 15.  If  these forces do not
act through the center-of-gravity (c.g.) 20 of the actuator, then a
net moment about the x-axis 13 of the actuator will result.

   In particular, if a net moment about the x-axis is
created by these forces, the "S" mode 30 will be excited.  This mode
of vibration involves head motion that degrades the settle
performance of the disk drive.

   The net moment (Mx) created by these forces can be
eliminated by placing the coil force 10 at the same z-height as the
c.g. 20 of the actuator, and by locating the bearings in the pivot
cartridge 15 equidistant from the c.g. 20.  This achieves geometric
symmetry and results in no ne...