JP2001051035A - Magnetic-field detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic-field detecting apparatus by which a magnetic field from a magnetic-field source in a desired space region can be detected selectively and efficiently. SOLUTION: A magnetic-field detection part 30 and a computing unit 40 are provided at this magnetic-field detecting apparatus. A coil 10 for magnetic- field detection and a coil 20 for a near-magnetic-field source are contained in the magnetic-field detection part 30. For example, the coil 10 for magnetic- field detection is constituted of a magnetometer, and the coil 20 for the near- magnetic-field source is constituted of a gradiometer. In the computing unit 40, a computing and processing operation according to the detection characteristic of the coil, for detection, with reference to a detected magnetic field is executed (the difference between both coils is found). Thereby, an influence from the near-magnetic-field source is suppressed, and a magnetic field can be outputted from a remote-magnetic-field source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic field detecting device, and more particularly to a magnetic field detecting device capable of detecting a magnetic field of a magnetic field source in a specific space region.

[0002]

2. Description of the Related Art Conventionally, there are two types of detection coils for magnetic field measurement (hereinafter referred to as detection coils): a magnetometer and a gradiometer.

[0003] The magnetometer is composed of one coil. The output of this detection coil detects all interlinking magnetic fields.

[0004] A gradiometer is composed of a plurality of coils. The Nth-order differential gradiometer has 2N coils, and can attenuate a magnetic field from a magnetic field source far from the measurement point by the difference between the coils.

[0005]

However, since the conventional detection coil has the above-described characteristics, for example, a detection coil from a magnetic field source existing in a desired space region such as a magnetic field source located far from the measurement point is used. There has been a problem that the magnetic field cannot be detected selectively and efficiently.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to selectively and efficiently detect a magnetic field from a magnetic field source existing in a desired space region. It is an object of the present invention to provide a magnetic field detection device capable of performing the above.

[0007]

According to one aspect of the present invention, there is provided a magnetic field detection apparatus comprising: a plurality of detection coils having different detection characteristics for detecting a magnetic field from a magnetic field source; An arithmetic processing unit that selectively outputs a magnetic field from a magnetic field source in a desired spatial region by executing an arithmetic process according to the characteristic.

Preferably, the plurality of detection coils have a first detection coil for detecting a magnetic field from a magnetic field source and a characteristic for efficiently detecting a magnetic field from a magnetic field source existing near a measurement point to be arranged. A second detection coil, wherein the arithmetic processing unit performs an arithmetic process on an output of the first detection coil and an output of the second detection coil, thereby obtaining a vicinity of a measurement point at which the plurality of detection coils are arranged. Attenuates the magnetic field from the magnetic field source existing in the sensor, and outputs the magnetic field from the magnetic field source located far from the measurement point where the plurality of detection coils are arranged. More preferably, the first detection coil is configured to include a magnetometer, and the second detection coil is configured to include a gradiometer. And more preferably, the difference between the output of the first detection coil and the output of the second detection coil is calculated by the arithmetic processing means.

Alternatively, the plurality of detection coils have a first detection coil having a characteristic of efficiently detecting a magnetic field from a magnetic field source existing near a measurement point to be arranged, and a first detection coil for efficiently detecting the magnetic field. And a second detection coil having a characteristic of efficiently detecting a magnetic field from a magnetic field to be generated and a magnetic field source located farther away, and the arithmetic processing means includes an output of the first detection coil and a second detection coil. By performing arithmetic processing on the output of the second detection coil, a magnetic field from a distant magnetic field source that can be efficiently detected by the second detection coil is selectively output. More preferably, the first detection coil includes a first gradiometer having a plurality of first coils having a short baseline, and the second detection coil includes a second gradiometer having a plurality of second coils having a long baseline. Configure to include a meter.

According to another aspect of the present invention, there is provided a magnetic field detecting device for detecting a magnetic field from a magnetic field source, and efficiently detecting a magnetic field from a magnetic field source existing near a measurement point to be arranged. A second detection coil having a characteristic of detecting;
By executing an arithmetic process using the outputs of the plurality of first detection coils and the outputs of the plurality of second detection coils,
Arithmetic processing means for selectively outputting a magnetic field from a magnetic field source located far from the measurement point where the plurality of first detection coils and the plurality of second detection coils are arranged. More preferably, each of the plurality of first detection coils includes a magnetometer, and each of the plurality of second detection coils includes a gradiometer.

Therefore, according to the above-described magnetic field detection apparatus, by executing arithmetic processing on the outputs of a plurality of detection coils having different characteristics, it is possible to efficiently detect a magnetic field from a magnetic field source in a desired space region. Becomes possible.

Further, by executing the arithmetic processing in accordance with the detection characteristics of the detection coil, it is possible to selectively detect a magnetic field from a distant magnetic field source. At this time, efficient detection is realized by using two coils having different characteristics and calculating the difference between the outputs of the two coils.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

A magnetic field detection device 100 according to an embodiment of the present invention will be described with reference to FIG. A magnetic field detection device 100 shown in FIG.
And a calculator 40 for detecting a magnetic field of the magnetic field source in a desired space region.

The magnetic field detector 30 includes a plurality of detection coils having different detection characteristics. FIG. 1 illustrates a magnetic field detection coil 10 and a proximity magnetic field source coil 20 as examples. These coils are arranged at measurement points.

The magnetic field detecting coil 10 is formed of, for example, a magnetometer. The proximity magnetic field source coil 20 includes:
It is composed of an N-order differential gradiometer (in FIG. 1, a first-order differential gradiometer).

The arithmetic unit 40 receives outputs from a plurality of detection coils included in the magnetic field detection unit 30 and executes an arithmetic process in accordance with the detection characteristics of the plurality of detection coils, thereby obtaining a desired spatial region. Calculate the magnetic field from the existing magnetic field source.

The arithmetic processing in the arithmetic unit 40 will be described. The magnetic field M detected by the magnetometer is given by equation (1)
Is represented by In the equation (1), Bmc is the magnetic field from the close magnetic field source detected by the magnetometer,
mf represents a magnetic field from a distant magnetic field source detected by the magnetometer, respectively.

M = Bmc + Bmf (1) The magnetic field G detected by the gradiometer is expressed by equation (2). In equation (2), Bgc is the magnetic field from the near magnetic field source detected by the gradiometer, Bgf
Represents the magnetic field from the distant magnetic field source detected by the gradiometer, respectively.

G = Bgc + Bgf (2) The arithmetic unit 40 executes an arithmetic processing function F on the magnetic fields M and G as shown in the equation (3).

B = F (M, G) (3) For example, the magnetic field M detected by the magnetometer (magnetic field detecting coil 10) and the gradiometer (proximity magnetic field source coil 20) are detected as the arithmetic processing function F. When the difference from the magnetic field G to be obtained is taken, the relationship of the following equation (4) is established.

B = F (M, G) = MG = (Bmc + Bmf) − (Bgc + Bgf) = (Bmc−Bgc) + (Bmf−Bgf) (4) Since the magnetic field from the source is attenuated, the effect from the near field source is reduced. Also,
As the distance (baseline) between the paired coils decreases, the gradiometer detects a magnetic field from a near magnetic field source rather than a far magnetic field source. Therefore, the following equation (5) holds. Equation (6) is obtained from relational equation (5). Here, the symbol Bc 'is a magnetic field from the attenuated near magnetic field source.

Bmf≫Bgf (5) B = Bc ′ + Bmf (6) That is, by executing the difference that is the arithmetic processing function F in the arithmetic unit 40, the magnetic field from the near magnetic field source among the detected magnetic fields is obtained. Is attenuated, and a magnetic field from a desired far magnetic field source can be selectively output.

The magnetic field detected by the gradiometer will be described with reference to FIG. FIG. 11 (A)
Corresponds to a first-order differential gradiometer, and FIG. 11B corresponds to a second-order differential gradiometer. As described above, the gradiometer includes a plurality of coils. The Nth-order differential gradiometer includes 2N coils and forms a pair every two coils. For example, the first-order differential gradiometer is formed of two coils C1 and C2 as shown in FIG.
For simplicity, the outputs of coils C1 and C2 are
1, C2. At this time, the value obtained by the following equation (7) becomes the output (detected magnetic field) G1 of the first-order differential gradiometer.

G1 = C1-C2 (7) On the other hand, the second-order differential gradiometer is formed of four coils C1, C2, C3 and C4 as shown in FIG. C2 and coil C
3 and C4 form a pair. For simplicity, the coils C1, C
2, C3, and C4 are output as C1, C2, and C4, respectively.
3, C4. At this time, the value obtained by the following equation (8) is the output (magnetic field to be detected) G2 of the second derivative gradiometer.

G1 = (C1−C2) − (C3−C4) (8) Each of the relational expressions (7) and (8) corresponds to the magnetic field G in the above description of the arithmetic processing.

The detection coils included in the magnetic field detection section 30 are not limited to those shown in FIG. The magnetic field detection device 200 shown in FIG. 12 uses a magnetic field detection coil 10 as an Nth-order differential gradiometer having a relatively long baseline L1 (distance between coils as constituent elements), and a proximity magnetic field source coil 20 as a base. Lines L2 (distance between coils as constituent elements) are each constituted by an Nth-order differential gradiometer which is relatively short (L2 <L1). Note that FIG. 12 illustrates a first-order differential gradiometer as an example.

As shown in FIG. 13, when the gradiometer has a short baseline (L1), the gradiometer efficiently detects the magnetic field from the magnetic field source A1 existing near the measurement point, and the gradiometer has a long baseline (L2). ), The magnetic field source A1 and the magnetic field source A
The magnetic field from the magnetic field source A2 located farther than 1 can be detected efficiently.

Therefore, the magnetic fields G01 and G02 are detected by using gradiometers having different detection characteristics. Then, the magnetic field G0 detected by the arithmetic unit 40
1 and G02 using the detection characteristics to execute arithmetic processing, it is possible to selectively output the magnetic field from the magnetic field source A2.

Further, the configuration of the magnetic field detector 30 is not limited to the configuration shown in FIG. The magnetic field detection unit 30 in the magnetic field detection device 300 shown in FIG. 14 includes a plurality of magnetic field detection coils 10 # 0,..., 10 # n-1, 10 # n and a plurality of proximity magnetic field source coils 20 # 0,. , 20 @ n-1, 20
♯n. As an example, a magnetic field detecting coil 10 #
Each of 0,..., 10 @ n-1 and 10 @ n is measured with a magnetometer using a proximity magnetic field source coil 20 # 0,.
Each of n−1 and 20♯n is a gradiometer (FIG. 1)
4 is a first-order differential gradiometer).

The magnetic field detecting coils 10 # 0,..., 1
Each of 0−１n−1 and 10♯n is not limited to those having the same characteristics, and coils 20 # 0,.
Each of {n-1, 20} n is not limited to those having the same characteristics.

The arithmetic unit 40 includes a magnetic field detecting coil 10 #
, 10 @ n-1, 10 @ n and the outputs of the proximity magnetic field source coils 20 # 0,..., 20 @ n-1, 20 @ n.

The arithmetic unit 40 performs an arithmetic operation on the magnetic field detected by the plurality of detection coils in accordance with the detection characteristics of these detection coils. This makes it possible to selectively output a magnetic field from a magnetic field source existing in a desired space region.

More specifically, for example, similarly to the magnetic field detection device 100, the magnetic field detection coils 10 # 0,.
{N-1, 10} n output and proximity magnetic field source coil 20}
By taking the difference from the outputs of 0,..., 20 @ n-1, 20 @ n, it is possible to selectively output a magnetic field from a magnetic field source existing in a spatial region far from the measurement point.

As described above, by using the magnetic field detecting device according to the embodiment of the present invention, it is possible to detect a defect or the like at a desired position inside the object in the nondestructive inspection of the object, for example. It is also possible to effectively detect nerve activity at a desired position in the brain.

[0036]

EXAMPLE Here, simulation experiments 1 and 2 were performed to confirm the effect of the magnetic field detection device 100 described above. Hereinafter, each of Experiments 1 and 2 will be described.

[Experiment 1] The experimental environment in Experiment 1 will be described with reference to FIG. As shown in FIG. 2, in Experiment 1, a magnetometer was used as the magnetic field detecting coil 10, and an axial gradiometer was used as the near magnetic field source coil 20.
Here, the center of the magnetometer is defined as (x, y, z) =
(0, 0, 0).

The coil diameter of the magnetometer and the coil diameter of the axial gradiometer are respectively
2.0 cm. The baseline of the axial gradiometer was 5.0 cm. The axial gradiometer was disposed immediately above the magnetometer (in the Z-axis direction), and the distance between the magnetometer and the axial gradiometer was 0.5 cm.

As the axial type gradiometer, a first-order differential type gradiometer and a second-order differential type gradiometer were used (note that FIG. 2 shows an axial type second-order differential gradiometer).

Two current dipoles 1 and 2 were used as magnetic field sources. In FIG. 2, the current dipoles 1 and 2 are represented by arrows, respectively. Current dipoles 1 and 2 are both y =
It was installed at a position of 3.0 cm. One current dipole 1 is z
= 4.0 cm and the other current dipole 2 is z
It was moved in the axial direction. The near field source is moved by the current dipole 1 and the far field source is simulated by moving the current dipole 2. The current dipole strength of each of the current dipoles 1 and 2 was 10 nAm.

In such an experimental environment, while moving the current dipole 2, the difference between the outputs of the two coils was obtained as the arithmetic processing of the arithmetic unit 40. This result will be described with reference to FIG.

FIG. 3 is a diagram for explaining a magnetic field detection result under the experimental environment shown in FIG. Symbols (M-G1) and (M-G2) shown in FIG. 3 indicate the results of the magnetic field detection in the presence of the current dipoles 1 and 2. More specifically, the symbol (M-G1) represents the result of subtracting the magnetic field detected by the axial first-order differential gradiometer from the magnetic field detected by the magnetometer, and the symbol (M-G2) represents the magnetometer. The results obtained by subtracting the magnetic field detected by the axial second-order differential gradiometer from the magnetic field detected by the meter are shown. The depth on the horizontal axis indicates the distance between the detection coil and the current dipole 2 in the z-axis direction.

In order to compare the ability to detect a magnetic field from a distant magnetic field source, the result of detecting the magnetic field of the current dipole 2 by using a single magnetometer as a detection coil is shown in FIG.
showed that.

When the current dipole 2 is close to the detection coil, the magnetic field detected is larger when the magnetometer is used alone. When the current dipole 2 moves away from the detection coil, the result of performing the arithmetic processing by combining the magnetometer and the axial gradiometer approaches the result of using the magnetometer alone. Then, when the current dipole 2 further moves away from the detection coil, the magnetic field detected by performing the arithmetic processing with the combination of the magnetometer and the axial gradiometer is smaller than when the magnetometer is used alone. growing.

That is, by using a magnetometer and an axial gradiometer as the detection coil and executing the arithmetic processing in the arithmetic unit 40, the magnetic field from the distant magnetic field source despite the presence of the near magnetic field source is obtained. It can be seen that is effectively detected.

FIG. 4 is a graph showing S in the experimental environment shown in FIG.
It is a figure showing the result of having computed the / N ratio. In FIG. 4, the magnetic field generated by the current dipole 1 is represented by magnetic noise,
And the S / N ratio shown in Expression (8) was plotted with respect to the position of the current dipole 2. Each symbol in FIG. 4 has a corresponding relationship with each symbol in FIG. S / N = (magnetic field by current dipole 2) / (magnetic field by current dipole 1) (8) If the position of current dipole 2 is close to the detection coil, it is better to detect using only a magnetometer. The S / N ratio is higher than when the arithmetic processing is performed by combining the meter and the axial gradiometer. However, when the position of the current dipole 2 moves away from the detection coil, the S / N ratio is reduced as compared with the case where only the magnetometer is used, by executing the arithmetic processing by combining the magnetometer and the axial gradiometer. Be improved. More specifically, when the depth was 12 cm, the improvement was 0.05.

That is, by using a magnetometer and an axial gradiometer as the detection coil and executing arithmetic processing in the arithmetic unit 40, the influence of noise from the near magnetic field source is removed, and the influence from the far magnetic field source is eliminated. A magnetic field can be output.

The magnetic field detection characteristics were examined by changing the current dipoles 1 and 2. This result will be described with reference to FIGS. 5 and 6, the current dipole 1 is set at z = 4.
It was arranged at a position of 0 cm, and the current dipole intensity was 2 nAm, and was changed at 100 Hz. Also, the current dipole 2 is z
= 7.0 cm and the current dipole intensity is 50 n
Am was changed at 10 Hz. In addition, in order to show each change of the current dipoles 1 and 2, a magnetic field waveform N when a magnetic field from the current dipole 1 is detected by a magnetometer,
The magnetic field waveform S when the magnetic field from the current dipole 2 is detected by the magnetometer is also shown in FIGS.

FIG. 5 is a diagram for explaining the magnetic field detection characteristics when a magnetometer and an axial primary differential gradiometer are combined. In FIG. 5, the symbol M
Is a magnetic field waveform detected by the magnetometer, symbol G1 is a magnetic field waveform detected by the first-order differential gradiometer, and symbol (M-G1) is a first-order differential gradiometer from the magnetic field detected by the magnetometer. Respectively show the magnetic field waveforms obtained by subtracting the magnetic field detected by.

Referring to FIG. 5, when the magnetic field from current dipoles 1 and 2 is detected using only the magnetometer, magnetic field waveform M is affected by the magnetic fields from both current dipoles 1 and 2. Change. When only the first-order differential gradiometer is used, the magnetic field waveform G1 changes under the influence of the magnetic field from the current dipole 1 more than in the case where only the magnetometer is used. On the other hand, by performing arithmetic processing (difference) by combining the magnetometer and the first-order differential gradiometer, the influence of the magnetic field from the current dipole 1 is reduced, and the magnetic field waveform (M-G1) is reduced. It can be seen that the change of the dipole 2 approaches.

FIG. 6 is a diagram for explaining the magnetic field detection characteristics when a magnetometer and an axial second-order differential gradiometer are combined. In FIG.
Represents the magnetic field detected by the magnetometer as G2
Is the magnetic field waveform detected by the second derivative gradiometer, and the symbol (M-G2) is the magnetic field obtained by subtracting the magnetic field detected by the second derivative gradiometer from the magnetic field detected by the magnetometer. The waveform is shown.

Referring to FIG. 6, when the magnetic field from current dipoles 1 and 2 is detected using only the magnetometer, magnetic field waveform M is affected by the magnetic fields from both current dipoles 1 and 2. Change. When only the second-order differential gradiometer is used, the detected magnetic field waveform G2 changes under the influence of the magnetic field from the current dipole 1 more than in the case where only the magnetometer is used. On the other hand, by performing arithmetic processing (difference) by combining the magnetometer and the second-order differential gradiometer, the influence of the magnetic field from the current dipole 1 is reduced, and the magnetic field waveform (M-G2) is reduced. It can be seen that the change of the current dipole 2 approaches.

Therefore, a magnetometer and an axial gradiometer are used as the detection coils, and
It has been confirmed that by executing the arithmetic processing in, the magnetic field of the distant magnetic field source can be selectively and efficiently detected. In addition, it was confirmed that magnetic field noise from the near magnetic field source could be easily removed.

[Experiment 2] The experimental environment in Experiment 2 will be described with reference to FIG. As shown in FIG. 7, in Experiment 2, a magnetometer was used as the magnetic field detecting coil 10 and a flat gradiometer was used as the near magnetic field source coil 20. Let the center of the magnetometer be (x, y, z) =
(0, 0, 0).

The diameter of the coil constituting the magnetometer is
The diameter of the coil constituting the planar gradiometer was 2.0 cm, and the diameter of the coil was 1.0 cm. The baseline of the flat-type gradiometer was set to 1.0 cm.

The flat-type gradiometer was placed in a magnetometer. The first-order gradiometer was used as the planar gradiometer. The conditions for the magnetic field source are the same as those described in FIG.

In such an experimental environment, while moving the current dipole 2,
The difference between the outputs of the two coils was taken. This result will be described with reference to FIG.

FIG. 8 is a diagram for explaining the results of magnetic field detection under the experimental environment shown in FIG. Symbols (M-G1) and (M-G2) shown in FIG. 8 indicate the results of the magnetic field detection in the presence of the current dipoles 1 and 2. More specifically, the symbol (M-G1) represents the result of subtracting the magnetic field detected by the planar gradiometer from the magnetic field detected by the magnetometer. The depth on the horizontal axis indicates the distance between the detection coil and the current dipole 2 in the z-axis direction.

In order to compare the ability to detect a magnetic field from a distant magnetic field source, the result of detecting the magnetic field of the current dipole 2 by using a single magnetometer as a detection coil is shown in FIG.
showed that.

When the current dipole 2 is close to the detection coil, the detected magnetic field is larger when the magnetometer is used alone. When the current dipole 2 moves away from the detection coil, the result of performing the arithmetic processing by combining the magnetometer and the flat type gradiometer approaches the result of using the magnetometer alone. Then, when the current dipole 2 further moves away from the detection coil, the magnetic field detected by performing the arithmetic processing by combining the magnetometer and the flat-type gradiometer is larger than when the magnetometer is used alone. growing.

That is, a magnetometer and a flat-type gradiometer are used as detection coils, and
By executing the predetermined arithmetic processing in, it can be seen that the magnetic field from the distant magnetic field source is effectively detected despite the presence of the near magnetic field source.

FIG. 9 shows a graph of S under the experimental environment shown in FIG.
It is a figure showing the result of having computed the / N ratio. In FIG. 9, the magnetic field generated by the current dipole 1 is represented by magnetic noise,
And the S / N ratio shown in Expression (8) was plotted with respect to the position of the current dipole 2. Each symbol in FIG. 9 has a corresponding relationship with each symbol in FIG.

When the position of the current dipole 2 is close to the detection coil, the detection using only the magnetometer is S / S compared with the case where the arithmetic processing is performed by combining the magnetometer and the planar gradiometer. High N ratio. However, when the position of the current dipole 2 moves away from the detection coil, the S / N ratio is reduced as compared with the case where only the magnetometer is used, by executing the arithmetic processing by combining the magnetometer and the planar gradiometer. Be improved. More specifically, when the depth was 12 cm, the improvement was 0.08.

That is, by using a magnetometer and a flat-type gradiometer as the detection coil and executing an arithmetic process in the arithmetic unit 40, the influence of noise from the near magnetic field source is removed, and the magnetic field from the far magnetic field source is removed. Can be output.

The magnetic field detection characteristics were examined by changing the current dipoles 1 and 2. This result will be described with reference to FIG. In FIG. 10, the current dipole 1 is arranged at a position of z = 2.0 cm, the current dipole intensity is 1 nAm, and 100H
varied with z. In addition, the current dipole 2 is set at z = 4.0 cm.
At a current dipole intensity of 50 nAm,
It was changed at 10 Hz. In FIG. 10, in order to show the respective changes of the current dipoles 1 and 2, the magnetic field waveform N when the magnetic field from the current dipole 1 is detected by the magnetometer and the magnetic field from the current dipole 2 are The magnetic field waveform S detected by the meter is also shown in FIG.

FIG. 10 is a diagram for explaining the magnetic field detection characteristics when a magnetometer and a planar primary differential gradiometer are combined. In FIG.
The symbol M is the magnetic field waveform detected by the magnetometer, the symbol G1 is the magnetic field waveform detected by the planar primary differential gradiometer, and the symbol (M-G1) is the magnetic field waveform detected by the magnetometer. The magnetic field waveforms obtained by subtracting the magnetic field detected by the planar primary differential gradiometer are shown.

Referring to FIG. 10, when the magnetic field from current dipoles 1 and 2 is detected using only the magnetometer, magnetic field waveform M is affected by the magnetic fields from both current dipoles 1 and 2. Change. When only the flat type gradiometer is used, the magnetic field waveform G1 changes under the influence of the magnetic field from the current dipole 1 more than in the case where only the magnetometer is used. On the other hand, by performing an arithmetic operation (difference) by combining a magnetometer and a planar gradiometer, the influence of the magnetic field from the current dipole 1 is reduced, and the magnetic field waveform (M-G1) is changed to the current dipole. It can be seen that the child 2 approaches the change.

Therefore, it is confirmed that the magnetic field of the distant magnetic field source can be selectively and efficiently detected by using the magnetometer and the planar gradiometer as the detection coils and executing the arithmetic processing in the arithmetic unit 40. Was. In addition, it was confirmed that magnetic field noise from the near magnetic field source could be easily removed.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0070]

As described above, according to the magnetic field detecting device of the present invention, the arithmetic processing is executed based on the outputs of the plurality of detecting coils having different detection characteristics, so that the magnetic field source in the desired spatial region can be obtained. Can be efficiently detected. In addition, it is possible to reduce magnetic field noise from a spatial region that is not a target.

Further, according to the magnetic field detecting apparatus of the present invention, the magnetic field from the magnetic field source located far away is selectively detected by executing the arithmetic processing in accordance with the detection characteristics of the detection coil formed. be able to. At this time, efficient detection is realized by using two detection coils having different characteristics and calculating the difference between the outputs of the two detection coils.

[Brief description of the drawings]

FIG. 1 is a magnetic field detection device 10 according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating an example of a configuration of a zero.

FIG. 2 is a diagram for explaining an experimental environment when a magnetometer and an axial gradiometer are used as detection coils.

FIG. 3 is a diagram for explaining a magnetic field detection result under the experimental environment shown in FIG. 2;

FIG. 4 is a diagram showing a result of calculating an S / N ratio under the experimental environment shown in FIG. 2;

FIG. 5 is a diagram for describing a magnetic field detection characteristic when a magnetometer and an axial primary differential gradiometer are combined.

FIG. 6 is a diagram for explaining a magnetic field detection characteristic when a magnetometer and an axial second-order differential gradiometer are combined.

FIG. 7 is a diagram for describing an experimental environment when a magnetometer and a planar gradiometer are used as detection coils.

FIG. 8 is a diagram for explaining a magnetic field detection result under the experimental environment shown in FIG. 7;

9 is a diagram showing a result of calculating an S / N ratio under the experimental environment shown in FIG.

FIG. 10 is a diagram for describing a magnetic field detection characteristic when a magnetometer and a planar primary differential gradiometer are combined.

11A is a diagram for explaining a first-order differential gradiometer, and FIG. 11B is a diagram for explaining a second-order differential gradiometer.

FIG. 12 is a diagram showing another configuration example of the magnetic field detection device according to the embodiment of the present invention.

FIG. 13 is a conceptual diagram for describing a detection characteristic of a gradiometer.

FIG. 14 is a diagram showing another configuration example of the magnetic field detection device according to the embodiment of the present invention.

[Explanation of symbols]

1, 2 current dipole, 10, 10♯0 to 10♯n magnetic field detection coil, 20, 20♯0 to 20♯n proximity magnetic field source coil, 30 magnetic field detection unit, 40 arithmetic unit, 100,
200, 300 Magnetic field detection device.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Itsuro Tamura 4-1-2, Hiranocho, Chuo-ku, Osaka-shi F-term in Kansai New Technology Research Institute Co., Ltd. (reference) 2G017 AA01 AD04 BA11

Claims (8)

[Claims] A plurality of detection coils having mutually different detection characteristics for detecting a magnetic field from a magnetic field source; and performing arithmetic processing on outputs of the plurality of detection coils in accordance with the detection characteristics to obtain a desired one. A magnetic field detection device comprising: a processing unit for selectively outputting a magnetic field from a magnetic field source in a spatial region. 2. The plurality of detection coils have a first detection coil for detecting a magnetic field from the magnetic field source, and a characteristic for efficiently detecting a magnetic field from a magnetic field source located near a measurement point to be arranged. A second detection coil having the plurality of detection coils, wherein the arithmetic processing means performs the arithmetic processing on the output of the first detection coil and the output of the second detection coil, thereby arranging the plurality of detection coils. 2. A magnetic field from a magnetic field source existing near a measurement point to be measured is attenuated, and a magnetic field from a magnetic field source located far from the measurement point where the plurality of detection coils are arranged is selectively output. 3. The magnetic field detection device according to claim 1. 3. The magnetic field detection device according to claim 2, wherein the first detection coil includes a magnetometer, and the second detection coil includes a gradiometer. 4. The magnetic field detection device according to claim 1, wherein the arithmetic processing unit calculates a difference between an output of the first detection coil and an output of the second detection coil. 5. A plurality of detection coils, a first detection coil having a characteristic of efficiently detecting a magnetic field from a magnetic field source existing near a measurement point to be arranged; And a second detection coil having a characteristic of efficiently detecting a magnetic field from the magnetic field and a magnetic field source located farther away. The arithmetic processing means includes an output of the first detection coil. The magnetic field from a distant magnetic field source which can be efficiently detected by the second detection coil by performing the arithmetic processing on the output of the second detection coil and the output of the second detection coil. Magnetic field detection device. 6. The first detection coil includes a first gradiometer having a plurality of first coils having a short baseline, and the second detection coil has a plurality of second coils having a long baseline. The magnetic field detection device according to claim 5, further comprising a second gradiometer. 7. A plurality of first sensors for detecting a magnetic field from a magnetic field source.
A detection coil, a plurality of second detection coils having a characteristic of efficiently detecting a magnetic field from a magnetic field source present in the vicinity of the measurement point to be arranged, an output of the plurality of first detection coils, and a plurality of second detection coils. 2
A magnetic field from a magnetic field source located far from a measurement point at which the plurality of first detection coils and the plurality of second detection coils are arranged is selected by performing an arithmetic process using the output of the detection coil. A magnetic field detection device comprising: 8. The magnetic field detection device according to claim 8, wherein each of the plurality of first detection coils includes a magnetometer, and each of the plurality of second detection coils includes a gradiometer.