Magnetic field measurement device

Patent metadata

Field	Value
Publication number	US-10191123-B2
Application number	US-201515502370-A
Country	US
Kind code	B2
Filing date	Jul 31, 2015
Priority date	Sep 10, 2014
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A magnetic field measurement device capable of accurate measurement of a magnetic field even after a sensitivity of an MI sensor varies is provided. A magnetic field measurement device (1) includes an MI sensor (2) and a sensitivity calculation means (3). The MI sensor (2) includes a magneto-sensitive body (20), a detection coil (21) and a magnetic field generation coil (22) that generates a magnetic field upon energization. The sensitivity calculation means (3) varies a current flowing in the magnetic field generation coil (22) in a state where an outside-sensor magnetic field HO acting on the magneto-sensitive body (20) from outside the MI sensor (2) is constant. Consequently, the magnetic field acting on the magneto-sensitive body (20) is varied to calculate a sensitivity a by dividing a variation in an output voltage of the detection coil (21) by a variation in the magnetic field acting on the magneto-sensitive body (20).

First claim

The invention claimed is:

1. A magnetic field measurement device for measuring a magnetic field, comprising:
a magneto-impedance sensor including:
a magneto-sensitive body,
a detection coil that is wound around the magneto-sensitive body and outputs a voltage corresponding to a magnetic field acting on the magneto-sensitive body, and
a magnetic field generation coil that is wound around the magneto-sensitive body and generates a magnetic field upon energization;

a sensitivity calculation means for calculating a sensitivity, the sensitivity being a value that is obtained by varying a value of a current flowing in the magnetic field generation coil to vary the magnetic field acting on the magneto-sensitive body in a state where an outside-sensor magnetic field that acts on the magneto-sensitive body from outside the magneto-impedance sensor is constant, and dividing a variation in an output voltage of the detection coil by a variation in the magnetic field acting on the magneto-sensitive body; and
a magnetic field calculation means,
wherein the magneto-impedance sensor is mounted on a device,
the outside-sensor magnetic field is a composition magnetic field of an outside-device magnetic field that acts on the magneto-sensitive body from outside the device and an inside-device magnetic field that is generated from an electronic component provided inside the device and acts on the magneto-sensitive body, and
the magnetic field calculation means calculates a value of the outside-device magnetic field using the sensitivity calculated by the sensitivity calculation means and the output voltage of the detection coil.

2. The magnetic field measurement device according to claim 1 , wherein the sensitivity calculation means varies the value of the current flowing in the magnetic field generation coil so that the inside-device magnetic field is cancelled out by a coil magnetic field generated from the magnetic field generation coil, and calculates the sensitivity in a process to vary the value of the current, and the magnetic field calculation means calculates the value of the outside-device magnetic field in a state where a magnitude of the magnetic field acting on the magneto-sensitive body is made to be smaller than a predetermined threshold value by feeding a current to the magnetic field generation coil.

3. The magnetic field measurement device according to claim 1 , wherein the voltage is proportional to the magnetic field acting on the magneto-sensitive body.

4. The magnetic field measurement device according to claim 1 , wherein the device is a mobile device.

5. A magnetic field measurement device for measuring a magnetic field, comprising:
a magneto-impedance sensor including:
a magneto-sensitive body,
a detection coil that is wound around the magneto-sensitive body and outputs a voltage corresponding to a magnetic field acting on the magneto-sensitive body, and
a magnetic field generation coil that is wound around the magneto-sensitive body and generates a magnetic field upon energization;

first circuitry configured to calculate a sensitivity, the sensitivity being a value that is obtained by varying a value of a current flowing in the magnetic field generation coil to vary the magnetic field acting on the magneto-sensitive body in a state where an outside-sensor magnetic field that acts on the magneto-sensitive body from outside the magneto-impedance sensor is constant, and dividing a variation in an output voltage of the detection coil by a variation in the magnetic field acting on the magneto-sensitive body; and
second circuitry,
wherein the magneto-impedance sensor is mounted on a device,
the outside-sensor magnetic field is a composition magnetic field of an outside-device magnetic field that acts on the magneto-sensitive body from outside the device and an inside-device magnetic field that is generated from an electronic component provided inside the device and acts on the magneto-sensitive body, and
the second circuitry calculates a value of the outside-device magnetic field using the sensitivity calculated by the first circuitry and the output voltage of the detection coil.

6. The magnetic field measurement device according to claim 5 , wherein the first circuitry varies the value of the current flowing in the magnetic field generation coil so that the inside-device magnetic field is cancelled out by a coil magnetic field generated from the magnetic field generation coil, and calculates the sensitivity in a process to vary the value of the current, and the second circuitry calculates the value of the outside-device magnetic field in a state where a magnitude of the magnetic field acting on the magneto-sensitive body is made to be smaller than a predetermined threshold value by feeding a current to the magnetic field generation coil.

7. The magnetic field measurement device according to claim 5 , wherein the voltage is proportional to the magnetic field acting on the magneto-sensitive body.

8. The magnetic field measurement device according to claim 5 , wherein the device is a mobile device.

Assignees

• Aichi Steel Corp

Inventors

• Nagao Tomohiko
• Yamamoto Michiharu

Classifications

• G01R33/0017 Primary

  Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields · CPC title

• G01R33/063 Primary

  Magneto-impedance sensors; Nanocristallin sensors · CPC title

• G01R33/02

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