Browse Prior Art Database

High Torque Voice Coil Actuator for Hard Disk Drive

IP.com Disclosure Number: IPCOM000014187D
Original Publication Date: 1999-Oct-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Joe Lo: AUTHOR [+4]

Abstract

Published is a voice coil design for hard disk drive application. A saddle-shapped voice coil is proposed as opposed to the conventional flat coil used by the industry. The saddle-coil design avoids the penalties associated with the added inertia and resistance of the conductor that joins the outer ends of the two radial legs of the conventional flat coil. Therefore, the saddle- shaped VCM is able to achieve higher Kt/J (torque constant of VCM over mass moment of inertia) and improved access time.

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High Torque Voice Coil Actuator for Hard Disk Drive

   Published is a voice coil design for hard disk drive application. A
saddle-shapped voice coil is proposed as opposed to the conventional flat coil
used by the industry. The saddle-coil design avoids the penalties associated with
the added inertia and resistance of the conductor that joins the outer ends of
the two radial legs of the conventional flat coil. Therefore, the saddle- shaped
VCM is able to achieve higher Kt/J (torque constant of VCM over mass moment of
inertia) and improved access time.

     Figure 1 shows an isometric model of the
saddle-shapped VCM. TheVCM consists of the
saddle-shaped coil, permanent magnets, top and
bottom steel plates, side plates and a center yoke.
The saddle-shapped coil is placed at the air gap
between magnets and the yoke. When controlled
current flows through the coil, force is generated
to move the suspension and head to a desired
position.

Figure 1. Schematic of the Saddle-Coil VCM

Two cases are analyzed in Table 1 for comparison
with the flat coil VCM. Case 1 is 15.5 mm VCM
z-height with 3.5 inches disks. Case 2 has
z-height of 31.7 mm and uses 3 inches disks.

Kt/J (Krad/As^2) flat-coil saddle-coil

15.5 mm height, 3.5" disk 22.8 31.9 (40% incr.)

31.7 mm height, 3" disk 26.6 37.6 (41% incr.)
Table 1.

Modeled
analysis
results for
Kt/J for

1

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various cases
of flat-coil
and
saddle-coil

2