Robert J Norton

US Patent:

43216919, Mar 23, 1982

Filed:

Jun 2, 1980

Appl. No.:

6/155337

Inventors:

Robert H. Norton - Menlo Park CA

Assignee:

National Semiconductor Corporation - Santa Clara CA

International Classification:

G11C 1908

US Classification:

365 8

Abstract:

A magnetic bubble detector stretches a single magnetic bubble domain across two isolated magneto-resistive sensors so that only one of the sensors needs to be functional in order to detect the presence of a magnetic bubble. The magnetic bubble domain can be striped actively by a local field created by a current loop. Alternatively, if the magnetic bubble domain is stretched passively by propagation along a progressively widening pattern of magnetic elements, the pattern can be separated into two isolated patterns, one associated with each sensor, so that only one of the pattern/sensor pairs needs to be functional in order to detect the presence of a magnetic bubble. An active bubble switch can be used as an alternative to the passive stretch array. The bubble switch is coupled to receive the activating current provided to one the sensors for directing magnetic bubble domains to that sensor in response to the application of an activating current to that sensor. Finally, the terminals of the magneto-resistive elements are interconnected in such a way as to facilitate testing of the sensors or sensor/pattern pairs and selective disabling of one of the sensors or sensor/pattern pairs.