Magnetic-field detecting device

Patent metadata

Field	Value
Publication number	US-9759785-B2
Application number	US-201214004035-A
Country	US
Kind code	B2
Filing date	Mar 5, 2012
Priority date	Mar 7, 2011
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A magnetic-field detecting device includes a pair of magneto-sensors including respective magnetism sensing portions that sense magnetism, and respective coils sensing changes of magnetic fluxes in the magnetism sensing portions, and an elongate connecting member cooperating with the magnetism sensing portions to constitute a magnetic circuit. A magnetism sensing direction of the magnetism sensing portions coincides with a longitudinal direction of the connecting member to an extent that permits the coils to equally sense a magnetic field applied to the coils the connecting member being formed of a magnetic material having a relative magnetic permeability of at least 100, a magnetic material having a relative magnetic permeability which is at least 1/100 of that of a magnetic material of the magnetism sensing portions, or the same magnetic material as the magnetism sensing portions the magnetic-field sensor measuring the magnetism on the basis of a difference between outputs of the coils.

First claim

The invention claimed is:

1. A magnetic-field detecting device comprising a pair of magneto-sensors including respective magnetism sensing portions each configured to detect a magnetism, and respective coils configured to sense changes of magnetic fluxes in said magnetism sensing portions, and an elongate connecting member cooperating with the magnetism sensing portions of said pair of magneto-sensors to constitute a magnetic circuit,
wherein a magnetism sensing direction of the magnetism sensing portions of said pair of magneto-sensors coincides with a longitudinal direction of said connecting member to an extent such that the coils are configured to equally sense a magnetic field applied to both of said magnetism sensing portions, and the magnetic sensing portions are identical and located symmetrically at distal ends with respect to a longitudinal midpoint of said magnetic circuit such that the magnetic field applied to both of said magnetism sensing portions is equally detected,
said connecting member being formed of a magnetic material having a relative magnetic permeability of at least 100, a magnetic material having a relative magnetic permeability which is at least 1/100 of that of a magnetic material of said magnetism sensing portions, or the same magnetic material as the magnetism sensing portions of said magneto-sensors, and
said magnetic-field detecting device being configured to measure the magnetism on the basis of a difference between outputs of the coils of said pair of magneto-sensors.

2. The magnetic-field detecting device according to claim 1 , wherein said connecting member consists of a plurality of connector segments, and said plurality of connector segments are spaced apart from each other by gaps having dimensions not larger than a cross sectional diameter of connecting portions of said connecting member, or disposed in contact with each other.

3. The magnetic-field detecting device according to claim 2 , wherein said gaps are filled with magnetic bodies having a relative magnetic permeability of at least 100.

4. The magnetic-field detecting device according to claim 1 , wherein the magnetism sensing portions of said pair of magneto-sensors and said connecting member are formed of a same material as a one-piece body.

5. The magnetic-field detecting device according to claim 1 , wherein the magnetism sensing portions of said pair of magneto-sensors are disposed close to each other via a gap having a dimension not larger than a cross sectional diameter of connecting portions of said magnetism sensing portions, or disposed in contact with each other.

6. The magnetic-field detecting device according to claim 1 , further comprising a magnetic shielding member for shielding a subject to be measured, and said pair of magneto-sensors.

7. The magnetic-field detecting device according to claim 1 , further comprising a grounded covering portion which is formed of a non-magnetic electrically conductive material and which covers at least the magnetism sensing portions of said pair of magneto-sensors.

8. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, and the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire, while said connecting member is an electrically conductive body,
the magnetic-field detecting device further comprising a parallel conductive body which is electrically connected in parallel to said connecting member and which is formed of a non-magnetic electrically conductive material.

9. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, and the magnetism sensing portions of said pair of magneto-sensors are provided by a plurality of amorphous wires,
and wherein said plurality of amorphous wires are electrically connected in parallel to each other.

10. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, while the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire,
and wherein at least one of said pair of magneto-sensors is provided with a crystalline metal wire which is electrically insulated from said amorphous wire and disposed along said amorphous wire.

11. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, while the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire,
and wherein a stray capacitance of said coils is determined such that a variation of an induced voltage generated by each of said detecting coils upon initiation of application of an electric current to said amorphous wire, and a variation of an induced voltage generated by said coil upon termination of application of the electric current to said amorphous wire take place continuously.

12. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, while the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire,
and wherein the magnetic-field detecting device measures: a value of integration of a variation of an induced voltage generated by each of said coils as a result of initiation of application of an electric current to said amorphous wire, during a time period including a moment of a peak value of said variation; a value of integration of a variation of an induced voltage generated by said each coil as a result of termination of application of the electric current to said amorphous wire, during a time period including a moment of a peak value of said variation; or a value obtained by subtracting the value of integration of the variation of the induced voltage generated by said each coil as the result of termination of application of the electric current to said amorphous wire during the time period including the moment of the peak value of said variation, from the value of integration of the variation of the induced voltage generated by said each coil as the result of initiation of application of the electric current to said amorphous wire during the time period including the moment of the peak value of said variation.

13. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, while the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire,
and wherein a width of a pulse of an electric current to be applied to said amorphous wire has a value almost corresponding to a half of a reciprocal of a frequency at which an impedance of said magnetic impedance sensors with respect to the magnetic field has an outstanding change.

14. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, while the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire,
and wherein a repeating frequency of a pulse of an electric current pulse to be applied to said amorphous wire is at least 10 kHz.

15. The magnetic-field detecting device according to claim 1 , wherein said pair of magneto-sensors are magnetic impedance sensors, while the magnetism sensing portions of said pair of magneto-sensors are provided by an amorphous wire,
and wherein the coils of said pair of magneto-sensors are electrically connected in series to each other such that electromotive forces generated by the coils of said pair of ma

Assignees

• Uchiyama Tsuyoshi
• Nakayama Shinsuke
• ATSUTA Satoshi
• Nat Univ Corp Nagoya Univ
• Fujidenolo Co Ltd

Inventors

• Uchiyama Tsuyoshi
• Nakayama Shinsuke
• ATSUTA Satoshi

Classifications

• G01R33/0094

  Sensor arrays · CPC title

• G01R33/02 Primary

  Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) · CPC title

• G01R33/063

  Magneto-impedance sensors; Nanocristallin sensors · CPC title

• G01R33/0023 Primary

  Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration (G01R33/0017 takes precedence) · CPC title