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Magnetic Shunts to Shield the Bearings and Rails of a Voice Coil Motor Actuator in a Magnetic Recording Disk File

IP.com Disclosure Number: IPCOM000060296D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Mawla, KA: AUTHOR

Abstract

In magnetic recording disk files, the read/write heads are accessed across the concentric data tracks on the disk by a voice coil motor actuator which comprises a low-mass movable coil which moves through a magnetic field provided by permanent magnets. The coil and attached actuator arm are supported and guided by sets of bearings which move on rails adjacent to the permanent magnets. The magnetic field passes from the fixed permanent magnets, through the movable coil, through the fixed iron core located in the center of the coil, through the coil again, and back through a support plate which supports the fixed permanent magnets. In certain voice coil motor designs, the magnetic field path may intercept the guide rails or the bearings and cause them to become magnetized, which affects the actuator performance.

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Magnetic Shunts to Shield the Bearings and Rails of a Voice Coil Motor Actuator in a Magnetic Recording Disk File

In magnetic recording disk files, the read/write heads are accessed across the concentric data tracks on the disk by a voice coil motor actuator which comprises a low-mass movable coil which moves through a magnetic field provided by permanent magnets. The coil and attached actuator arm are supported and guided by sets of bearings which move on rails adjacent to the permanent magnets. The magnetic field passes from the fixed permanent magnets, through the movable coil, through the fixed iron core located in the center of the coil, through the coil again, and back through a support plate which supports the fixed permanent magnets. In certain voice coil motor designs, the magnetic field path may intercept the guide rails or the bearings and cause them to become magnetized, which affects the actuator performance. This problem can be avoided, and the necessity for using nonmagnetic guide rails or bearings eliminated, if a magnetically permeable shunt material, which is either a separate element or an extension of the magnet support plate, is located in the vicinity of the rails or the bearings to divert the magnetic field through the shunt and away from the bearings and rails.

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