GB1263271A - Improvements relating to thin film magnetic storage elements - Google Patents

Abstract

1,263,271. Magnetic storage apparatus. E.M.I. Ltd. 25 March, 1969 [17 Feb., 1968], No. 7877/68. Heading H3B. A non-destructive read-out magnetic storage element comprises three anisotropic magnetic thin films 1, 2, 3 overlying one another with their easy axes parallel to arrow 4 and an address conductor 5 and digit conductor 6 arranged parallel to and orthogonal to the easy axes respectively. When a signal is applied to address conductor 5 a closed flux path 8 is formed round the conductor rotating the magnetizations of films 1 and 2 parallel with the hard axes of the films and inducing a signal in digit/sense conductor 6 depending on the binary digit stored in films 2, 3. The magnetization of film 3 is only partly rotated from the easy axis so that when the address signal terminates the magnetization of film 3 returns to its original position and this in turn is effective on the film portion 2 to return it also to its original position because of the closed flux path 7. Film 1 becomes demagnetized in the absence of the address pulse. To write information into the storage element a digit drive signal is applied to conductor 6 straddling the trailing edge of the address pulse. A magnetic keeper portion of ferrite may be provided underneath but separated from film 3 to assist in the rotation of the magnetization of film 3 during an address drive signal and to reduce any residual flux flowing around conductor 6 due to the magnetization of film 3 by itself. Separate digit and sense conductors may be used. A plurality of elements may be arranged in a matrix.