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Keeper Structures for Coupled Film Memories

IP.com Disclosure Number: IPCOM000094151D
Original Publication Date: 1966-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 88K

Publishing Venue

IBM

Related People

Chang, H: AUTHOR [+5]

Abstract

A coupled-film memory device of the closed-easy-axis type can be so constructed as to provide hard-axis flux closures both above and below the bit-sense line during the application of the word field. Thus hard-axis magnetic flux is diverted away from the bit-sense line. Such is for the purpose of reducing undesired flux trapping or eddy current effects therein and also reducing the hard-axis demagnetizing field of the bottom film.

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Keeper Structures for Coupled Film Memories

A coupled-film memory device of the closed-easy-axis type can be so constructed as to provide hard-axis flux closures both above and below the bit- sense line during the application of the word field. Thus hard-axis magnetic flux is diverted away from the bit-sense line. Such is for the purpose of reducing undesired flux trapping or eddy current effects therein and also reducing the hard-axis demagnetizing field of the bottom film.

In a conventional closed-easy-axis memory device, application of the word drive causes the hard-axis flux in both the top and bottom films to be partially closed through a single keeper which is positioned above both of these films. Some of the hard-axis flux in the bottom film passes through both the bit-sense line and top film in order to close through the keeper. As successive word drives are applied and removed, this portion of the bottom film flux causes undesired eddy-current effects, i.e., flux trapping, to occur in the bit-sense line. The portion of the hard-axis flux in the bottom film that does not close through the keeper, which is positioned nearer the top film, sets up a hard-axis demagnetizing field that requires a larger word current to overcome it. It also can cause flux trapping and current spreading effects in the ground plane.

These disadvantages can be avoided by utilizing a coupled-film memory device constricted as shown at A, B, or C. In device A the word current returns through a bottom conductor that is separated...