EP0262879A2
Expired / Lapsed
EP
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Magnetic field sensor
Assignee: BTG International Ltd
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Filing: 1987-09-25
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Granted: —
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Expires: 2007-09-25
Abstract
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.
Inventors
- 👤 Theodore Patrick Squire
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 17:58
CPC Classifications
G; G01; G01H; G01H5/00; G01R; G01R33/00; G01R33/02
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
41 words
magnetic field sensor including a body of amorphous magnetic material and means to propagate ultrasound in said body together with means to detect variation with ambient magnetic field strength in the effect of the body on the propagation of ultrasound therein.
Claim 2
Dependent Claim
41 words
magnetic field sensor including a body of amorphous magnetic material and means to propagate ultrasound in said body together with means to detect variation with ambient magnetic field strength in the effect of the body on the propagation of ultrasound therein.
Claim 3
Dependent Claim
21 words
A sensor according to Claim 1 in which the body of magnetic material is of metallic glass which has magnetoelastic properties.
Claim 4
Dependent Claim
14 words
A sensor according to Claim 1 in which the body is elongate in form.
Claim 5
Dependent Claim
17 words
A sensor according to Claim 1 in which the body has been produced in the amorphous phase.
Claim 6
Dependent Claim
23 words
A sensor according to Claim 5 in which the body has been produced in the amorphous phase by melt spinning as a strip.
Claim 7
Dependent Claim
15 words
A sensor according to Claim 1 in which the ultrasound is propagated as shear waves.
Claim 8
Dependent Claim
25 words
A sensor according to Claim 1 in which the means to propagate ultrasound includes a radio frequency generator, a transmitter transducer and a receiver transducer.
Claim 9
Dependent Claim
20 words
A sensor according to Claim 1 in which the means to propagate ultrasound is effective over a range of frequencies.
Claim 10
Dependent Claim
20 words
A sensor according to Claim 8 in which the range of frequencies is at least 0.1 MHz to 100 MHz.
Claim 11
Dependent Claim
12 words
A sensor according to Claim 8 in which the transducers are piezoelectric.
Claim 12
Dependent Claim
18 words
A sensor according to Claim 10 in which the transducers are held to the body by rigid adhesive.
Claim 13
Dependent Claim
12 words
A sensor according to Claim 3 including transducers spaced along the body.
Claim 14
Dependent Claim
17 words
A sensor according to Claim 1 including means to apply a specific magnetic field to the body.
Claim 15
Dependent Claim
18 words
A sensor according to Claim 13 in which the applied field magnitude is one of steady and variable.
Claim 16
Dependent Claim
12 words
A sensor according to Claim 14 in which the variation is regular.
Claim 17
Dependent Claim
19 words
A sensor according to Claim 15 in which the field is generated by the application of an alternating current.
Claim 18
Dependent Claim
24 words
A sensor according to Claim 13 in which the field is applied in dependence on a required or perceived operating state of the sensor.
Claim 19
Dependent Claim
22 words
A sensor according to Claim 13 in which the specific magnetic field is arranged to bias the operating point of the sensor.
Claim 20
Dependent Claim
23 words
A sensor according to Claim 1 in which the means to detect variation of propagation with ambient magnetic field is a phase meter.
Claim 21
Dependent Claim
40 words
A sensor according to Claim 15 in which the means to detect variation of propagation includes a phase detector responsive to the output of a receiver transducer and a phase sensitive detector responsive to the output of the phase detector.
Claim 22
Dependent Claim
23 words
A sensor according to Claim 1 in which the means to detect variation of propagation with ambient magnetic field is responsive to amplitude.
Claim 23
Dependent Claim
20 words
A sensor according to Claim 19 in which the detector is a high frequency lock-in amplifier with a phase option.
Claim 24
Dependent Claim
44 words
A sensor according to Claim 1 in which 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.
Claim 25
Independent Claim
48 words
A method of sensing a magnetic field including supporting a body of amorphous magnetic material for exposure to a field to be sensed, propagating ultrasound in said body and detecting variation with ambient magnetic field strength in the effect of the body on the propagation of ultrasound therein.
Claim 26
Independent Claim
48 words
A method of sensing a magnetic field including supporting a body of amorphous magnetic material for exposure to a field to be sensed, propagating ultrasound in said body and detecting variation with ambient magnetic field strength in the effect of the body on the propagation of ultrasound therein.
References Cited (Backward Citations)
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