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On-Head Shield for a Hard File Servo Head

IP.com Disclosure Number: IPCOM000037619D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brooks, WW, Jr: AUTHOR [+4]

Abstract

An on-head shield for a hard file servo head is described. The shield can be used as an effective alternative to the various combinations of fixed ferrite shields typically used to reduce the pickup voltage from stray high frequency magnetic fields.

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On-Head Shield for a Hard File Servo Head

An on-head shield for a hard file servo head is described. The shield can be used as an effective alternative to the various combinations of fixed ferrite shields typically used to reduce the pickup voltage from stray high frequency magnetic fields.

For a shield on a monolithic tri-rail ferrite head, a four-sided box of ferrite or ferrite-based material is constructed by machining, molding, or pressing processes, and is attached to the rear of the head, surrounding the coil and back core of the head. The shield is positioned near the disk surface, but with sufficient clearance for the head to fly normally. The head body provides the fifth side of the box around the back core and coil. The open sixth side of the box is nearly blocked from high frequency flux entry by the eddy current limiting of the disk substrate. The shield thus prevents almost all stray, high frequency, magnetic fields from terminating on, or emanating from the back core, by bypassing the flux around the core, which prevents the generation of extraneous signals in the head winding.

The formation of a less complete box enclosure can be fabricated with less effort, but this results in less effective shielding, which may still be adequate in some cases. Such a design may be a shield in the shape of a "C", which is placed around the back of the head.

Similar shields or partial shields may be constructed for composite ferrite heads. However the ceramic, in w...