Magnetic field sensor using variations in ultrasound to determine magnetic field
US4891587A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 3, 1988 |
| Grant date | Jan 2, 1990 |
| Priority date | — |
| Expiry date | Nov 3, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A magnetic field sensor including a body of amorphous magnetic material [C] and means to propagate ultrasound [A.B.D.] in said body together with means [E,F; PD, PSD, F] to detect variation with ambient magnetic field strength in the effect of the body on the propagation of ultrasound therein. The ultrasound is propagated as zero-mode shear wave, said mode being controlled by having the thickness of the body of amorphous magnetic material below a critical value which is the quotient of velocity divided by frequency. A specific magnetic field [G,J; G,M] can be applied to control the operating point of the sensor. The field can be alternating and the effect on propagation detected by a phase detector followed by a phase sensitive detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.