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Composite Recording Head Design

IP.com Disclosure Number: IPCOM000061852D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Palmer, DC: AUTHOR

Abstract

The increased conductivity of MnZn ferrite has led to increased electrical noise susceptibility for conventional monolithic recording heads. The outer rail surface and the disk surface form a capacitor to pick up electrical noise which exists on the disk. The increase in electrical noise sensitivity has been particularly dramatic in the recent higher density disk files and has required many extra and costly measures to try to reduce the amount of noise entering the disk enclosure. One way to solve this problem is the use of a composite head structure. In this design only the magnetic circuit near the recording gap is made of MnZn ferrite and the rest of the slider is non-conducting material. The non-conducting outer rails do not pick up electrical noise, and so the noise sensitivity is greatly reduced.

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Composite Recording Head Design

The increased conductivity of MnZn ferrite has led to increased electrical noise susceptibility for conventional monolithic recording heads. The outer rail surface and the disk surface form a capacitor to pick up electrical noise which exists on the disk. The increase in electrical noise sensitivity has been particularly dramatic in the recent higher density disk files and has required many extra and costly measures to try to reduce the amount of noise entering the disk enclosure. One way to solve this problem is the use of a composite head structure. In this design only the magnetic circuit near the recording gap is made of MnZn ferrite and the rest of the slider is non-conducting material. The non-conducting outer rails do not pick up electrical noise, and so the noise sensitivity is greatly reduced. The small amount of MnZn near the gap does not provide appreciable electrical coupling to the disk. The disadvantage of this particular composite design is that the efficiency of the magnetic circuit is significantly reduced. This reduction is caused by the use of relatively thin sheets of MnZn, which results in much higher reluctance in the magnetic path. Monolithic MnZn heads maintain higher efficiency because the area of the magnetic path becomes relatively larger only a short distance away from the gap region. An alternative design for a composite head will be described which retains most of the advantages of the above composite head, but does not result in lower efficiency. The essential feature of this alternative is to make most or all of the outer rails from a non- conducting material but to keep enough MnZn in the region of the gap so that the magnetic circuit has the same efficiency as a monolithic head. The...