MAGNETORESISTIVE LINEAR DISPLACEMENT SENSOR, ANGULAR DISPLACEMENT SENSOR, AND VARIABLE RESISTOR

摘要

A giant magnetoresistance displacement sensor includes at least one layered structure. This layered structure includes a harder magnetic (ferromagnetic or antiferromagnetic) layer (34) having a fixed magnetic state, a second, softer magnetic layer (32) and a metal layer (33) interposed between and contacting these two layers (32, 34) to prevent exchange coupling between the two layers. The sensor also includes means (56, 58) for inducing a domain wall (37) at a measurand position, between regions (35, 36) of nonaligned magnetic fields in the softer magnetic layer (32), and means (50) for measuring electrical resistance between points on opposite sides of the structure. In operation, the means (56, 58) for inducing a domain wall, typically one or more indexing magnets (56, 58), is positioned relative to the giant magnetoresistance strip. The resistance across the strip is measured, and from this resistance measurement the position of the domain wall is determined. The present invention is also a variable resistor, which is operated by positioning the means (56, 58) for inducing the domain wall at a selected position, to set the resistance across the strip to a desired value.