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Electromagnetic Transducer With Thin Film Pole Pieces

IP.com Disclosure Number: IPCOM000078291D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Paton, A: AUTHOR

Abstract

An electromagnetic transducer has a substrate 1 comprising a ferrite block 2 bonded to a glass edge portion 3. Deposited on the substrate 1 is a permalloy thin-film pole piece 4 and a permalloy yoke closure 5. A multi turn copper winding 6 in the form of a flat spiral strip (only half of which is shown) is deposited over the pole piece 4 and the block 2. Another substrate 7, comprising a ferrite block 8 and a glass edge portion 9 and having a similar deposited permalloy pole piece 10, is bonded over the substrate 1 as shown. The pole pieces 4 and 10, the ferrite blocks 2 and 8 and the closure 5, form a magnetic yoke around the winding 6. A transducing gap is defined by the spaced apart tips of the pole pieces 4 and 10.

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Electromagnetic Transducer With Thin Film Pole Pieces

An electromagnetic transducer has a substrate 1 comprising a ferrite block 2 bonded to a glass edge portion 3. Deposited on the substrate 1 is a permalloy thin-film pole piece 4 and a permalloy yoke closure 5. A multi turn copper winding 6 in the form of a flat spiral strip (only half of which is shown) is deposited over the pole piece 4 and the block 2. Another substrate 7, comprising a ferrite block 8 and a glass edge portion 9 and having a similar deposited permalloy pole piece 10, is bonded over the substrate 1 as shown. The pole pieces 4 and 10, the ferrite blocks 2 and 8 and the closure 5, form a magnetic yoke around the winding 6. A transducing gap is defined by the spaced apart tips of the pole pieces 4 and 10.

Such a transducer reduces the problem of flux leakage across the yoke, by providing a low-reluctance flux path around the winding. A low-leakage yoke structure permits increased yoke height 'h' and a correspondingly greater number of turns in the winding. At least one thin-film pole piece protruding beyond its associated magnetic block yoke member is essential to obtaining a well defined gap field, when recording current is applied to the transducer. A well-defined field enables the transducer to record information at a higher density than could be achieved without a thin-film pole piece.

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