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Keeper Structure for Reducing Magnetization Spread

IP.com Disclosure Number: IPCOM000090945D
Original Publication Date: 1969-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Chang, H: AUTHOR [+2]

Abstract

Magnetization spread in a magnetic film memory is reduced by using a keeper in combination with a magnetic shield on the ground plane. Although the function of a keeper is to reduce the spread of stray magnetization between adjacent bit positions during those periods when the drive line adjoining the keeper is being energized, the effectiveness of the keeper can be impaired by the image field produced by the ground plane.

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Keeper Structure for Reducing Magnetization Spread

Magnetization spread in a magnetic film memory is reduced by using a keeper in combination with a magnetic shield on the ground plane. Although the function of a keeper is to reduce the spread of stray magnetization between adjacent bit positions during those periods when the drive line adjoining the keeper is being energized, the effectiveness of the keeper can be impaired by the image field produced by the ground plane.

This coupled film memory structure has permalloy keeper 1 positioned above an associated drive line 2, which is the word drive line in most cases. Storage film 3, assumed to be a coupled film with closed edges, is positioned around a drive line 4, usually the bit drive line, located between line 2 and ground plane 5, which generally serves as a return path for the drive currents in lines 2 and 4. Normally, the magnetic flux in film 3 is closed around line 4. During switching intervals, when line 2 is energized, the stray flux from film 3 should close through keeper 1 in the shortest possible path, with no substantial spreading of the flux away from line 2. However, the image field produced by the return current from line 2, flowing in plane 5, opposes the magnetizing field applied to keeper 1 by the drive current in line 2. As a result, the flux closure through keeper 1 is not as effective as it should be, i.e., the reluctance of the magnetic path through keeper 1 appears to be relatively high....