WO2020071511A1 - Magnetism detection device, transmission line, and magnetism detection method - Google Patents

Abstract

This magnetism detection device 1 comprises a transmission line 10 that has a wire-like first conductor 11 including a magnetic material, a signal generator 30 that applies a pulse to the transmission line 10 as an incident wave, and a calculation device 20 that detects the incident wave and a reflected wave produced by an impedance difference at a magnetic field application position on the transmission line 10. The calculation device 20 calculates the position and intensity of a magnetic field applied to the transmission line 10 on the basis of the incident wave and reflected wave.

Description

Magnetic detection device, transmission line, and magnetic detection method Cross-reference of related applications

This application claims the priority of Japanese Patent Application No. 2018-190387 filed in Japan on October 5, 2018 and Japanese Patent Application No. 2019-182846 filed in Japan on Oct. 3, 2019. And the entire disclosure of that application is incorporated herein by reference.

The present disclosure relates to a magnetic detection device, a transmission line, and a magnetic detection method.

Conventionally, a magnetic detection device capable of detecting a magnetic field has been known.

For example, Patent Document 1 discloses a magnetic field detection device in which a magnetic material whose magnetic permeability changes due to a magnetic field is arranged inside a distributed constant circuit. This magnetic field detection device can detect a magnetic field at a predetermined position by detecting a change in an electromagnetic field distribution in a distributed constant circuit caused by a change in the magnetic permeability of a magnetic substance due to a magnetic field.

JP-A-5-151535

(4) The magnetic field detection device described in Patent Document 1 can detect a magnetic field at a predetermined position, but cannot detect a magnetic field at an arbitrary position of a distributed constant circuit.

Therefore, an object of the present disclosure is to provide a magnetic detection device, a transmission line, and a magnetic detection method capable of detecting a magnetic field at an arbitrary position of a distributed constant circuit.

A magnetic detection device according to some embodiments includes a transmission line including a linear first conductor including a magnetic material, a signal generator configured to input a pulse as an incident wave to the transmission line, and a magnetic field applied to the transmission line. A reflected wave generated due to impedance mismatch at a position, and an arithmetic unit for detecting the incident wave, wherein the arithmetic unit is applied to the transmission line based on the incident wave and the reflected wave. Calculate the position and strength of the magnetic field. According to such a magnetic detection device, it is possible to detect a magnetic field at an arbitrary position in the distributed constant circuit.

In the magnetic detection device according to one embodiment, the arithmetic device calculates a position of the magnetic field applied to the transmission line based on a difference between a time when the incident wave is detected and a time when the reflected wave is detected. May be. Thereby, the arithmetic unit can accurately calculate the position of the magnetic field applied to the transmission line.

In the magnetic detection device according to one embodiment, the arithmetic device may calculate the strength of the magnetic field applied to the transmission line based on the amplitude of the reflected wave. Accordingly, the arithmetic device can calculate the strength of the magnetic field applied to the transmission line with high accuracy.

In the magnetic detection device according to one embodiment, the arithmetic unit detects data in a state where a magnetic field is not applied to the transmission line as offset data, and detects a reflected wave in a state where a magnetic field is applied to the transmission line. The difference data obtained by subtracting the offset data from the data may be used as reflected wave data for calculating the position and intensity of the magnetic field. Thereby, the arithmetic unit can reduce the influence of the reflected wave caused by the mechanical tolerance of the components of the transmission line.

In the magnetic detection device according to one embodiment, the transmission line further includes a dielectric and a second conductor, and includes any one of a coaxial cable, a parallel two line, a strip line, a microstrip line, a coplanar line, and a waveguide. It may be. As described above, by using a coaxial cable as the transmission line, the transmission line can have flexibility. Further, the transmission line can be made flexible by forming two parallel lines, a strip line, a microstrip line, a coplanar line, or a waveguide using a flexible substrate.

に お い て In the magnetic detection device according to one embodiment, the first conductor may be such that a magnetic material is substantially uniformly distributed, or a magnetic film containing a magnetic material may be formed on the conductor surface. In the first conductor, since the magnetic film containing the magnetic material is formed on the conductor surface, it is possible to make it difficult for hysteresis to occur.

に お い て In the magnetic detection device according to one embodiment, the transmission line may include a plurality of the first conductors. As described above, since the transmission line includes the plurality of first conductors, the resistance loss of the transmission line can be reduced.

磁 気 The magnetic detection device according to one embodiment may further include a coil for applying a bias magnetic field to the transmission line. By providing the transmission line with the coil that applies the bias magnetic field, it is possible to determine whether a positive magnetic field is applied or a negative magnetic field is applied.

In the magnetic detection device according to one embodiment, the pulse may be any one of a rectangular wave, a sine wave, a triangle wave, and a sawtooth wave. Thus, the pulses generated by the signal generator can be of various shapes.

In the magnetic detection device according to one embodiment, the signal generator sweeps a sinusoidal pulse as the incident wave and inputs the pulse to the transmission line, and the arithmetic unit scans the incident wave that is input by sweeping. For each frequency, obtain the amplitude and phase difference of the reflected wave with respect to the incident wave, generate frequency domain data of reflectance based on the amplitude of the reflected wave with respect to the incident wave, and generate the reflected wave with respect to the incident wave Generating frequency domain data of the phase difference based on the phase difference, generating the time domain data of the reflected wave by performing an inverse Fourier transform of the frequency domain data of the reflectance and the frequency domain data of the phase difference, The position and intensity of the magnetic field applied to the transmission line may be calculated. As described above, by generating the frequency domain data of the reflectance and the frequency domain data of the phase difference based on the amplitude and the phase difference of the reflected wave with respect to the incident wave, even if the incident wave fluctuates, the fluctuation is canceled. The vector ratio of the reflected wave to the incident wave can be detected. Accordingly, the jitter of the incident wave can be removed, and a synchronized measurement without fluctuation of the signal over time can be performed.
it can.

In the magnetic detection device according to one embodiment, the signal generator sweeps the sine wave pulse and inputs the sine wave pulse to the transmission line, and the arithmetic device calculates the frequency domain data of the reflectance and the frequency of the phase difference. Either generate time domain data of the reflected wave as an impulse response by performing an inverse Fourier transform of the domain data, or integrate the frequency domain data of the reflectivity and the frequency domain data of the phase difference subjected to the inverse Fourier transform. Time domain data of the reflected wave may be generated as a response. As described above, by generating the time domain data of the reflected wave as the impulse response or the step response, the position and the intensity of the magnetic field applied to the transmission line can be accurately calculated.

In the magnetic detection device according to one embodiment, the signal generator sweeps the sine wave pulse and inputs the sine wave pulse to the transmission line, and the arithmetic device calculates the frequency domain data of the reflectance and the frequency of the phase difference. A convolution integral process may be performed on the domain data to perform an inverse Fourier transform, and time domain data of the reflected wave may be generated as a step response. As described above, by performing the convolution integration processing, the time required for the calculation can be reduced as compared with the case where the integration processing is performed after performing the inverse Fourier transform.

A transmission line according to some embodiments is a transmission line used for detecting a magnetic field, in which a magnetic material is substantially uniformly distributed, or a signal in which a magnetic film including a magnetic material is formed on a conductor surface. With lines. By using such a transmission line, it is possible to detect a magnetic field at an arbitrary position of the distributed constant circuit.

A magnetic detection method according to some embodiments is a magnetic detection method in a magnetic detection device including a transmission line including a linear first conductor including a magnetic material, a signal generator, and an arithmetic device, The signal generator inputs a pulse as an incident wave to the transmission line, and the arithmetic unit detects a reflected wave caused by impedance mismatch at a magnetic field application position of the transmission line and the incident wave. And calculating the position and intensity of the magnetic field applied to the transmission line based on the incident wave and the reflected wave. According to such a magnetic detection method, it is possible to detect a magnetic field at an arbitrary position in the distributed constant circuit.

It is a figure showing the schematic structure of the magnetic sensing device concerning one embodiment. It is a figure showing the schematic structure of the transmission line concerning one embodiment. FIG. 2 is a diagram showing how a magnetic field is detected by the magnetic detection device of FIG. 1. FIG. 3 is a diagram illustrating a state in which a transmission line is represented as a distributed constant circuit. FIG. 4 is a diagram illustrating an example of an incident wave and a reflected wave detected by the arithmetic device. FIG. 3 is a diagram illustrating a relationship between a magnetic field applied to a transmission line and an amplitude of a reflected wave. FIG. 3 is a diagram illustrating an example of an incident wave in a transmission line. FIG. 3 is a diagram illustrating an example of an incident wave and a reflected wave in a transmission line. FIG. 3 is a diagram illustrating an example of an incident wave and a reflected wave in a transmission line. FIG. 9 is a diagram illustrating another example of an incident wave in a transmission line. FIG. 9 is a diagram illustrating another example of the incident wave and the reflected wave in the transmission line. FIG. 9 is a diagram illustrating another example of the incident wave and the reflected wave in the transmission line. It is a figure showing other examples of a schematic structure of a transmission line constituted as a coaxial cable. It is a figure showing other examples of a schematic structure of a transmission line constituted as a coaxial cable. FIG. 3 is a diagram illustrating an example of a transmission line that is not configured as a coaxial cable. FIG. 3 is a diagram illustrating an example of a transmission line that is not configured as a coaxial cable. FIG. 3 is a diagram illustrating an example of a transmission line that is not configured as a coaxial cable. FIG. 3 is a diagram illustrating an example of a transmission line that is not configured as a coaxial cable. FIG. 3 is a diagram illustrating a state where a bias magnetic field is applied by a coil arranged around a transmission line. FIG. 6 is a diagram illustrating a relationship between a magnetic field and an amplitude of a reflected wave in a state where a bias magnetic field is applied. It is a figure showing the schematic structure of the magnetic sensing device concerning other embodiments. FIG. 14 is a diagram showing how a magnetic field is detected by the magnetic detection device of FIG. 13. FIG. 14 is a diagram illustrating an example of an incident wave in the magnetic detection device in FIG. 13. FIG. 14 is a diagram illustrating an example of an amplitude of an incident wave in the magnetic detection device in FIG. 13. FIG. 14 is a diagram illustrating an example of a reflectance of a reflected wave with respect to an incident wave in the magnetic detection device of FIG. 13. FIG. 14 is a diagram illustrating an example of a phase difference between a reflected wave and an incident wave in the magnetic detection device in FIG. 13. It is a figure showing an example when frequency domain data of a reflectance and frequency domain data of a phase difference are converted into time domain data of a reflected wave. It is a figure showing an example when frequency domain data of a reflectance and frequency domain data of a phase difference are converted into time domain data of a reflected wave. It is a figure showing an example when frequency domain data of a reflectance and frequency domain data of a phase difference are converted into time domain data of a reflected wave.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the description of this specification, terms relating to a magnetic field are used in the following meaning.
"Magnetic field": A generic term including a magnetic field to be measured (external magnetic field), an environmental magnetic field, a bias magnetic field, and the like.
"A magnetic field at a predetermined (arbitrary) position": a magnetic field including an external magnetic field and an environmental magnetic field.
“External magnetic field (magnetic field applied to transmission line)”: a magnetic field that is not in the initial state but is applied to the transmission line from outside and is generated by a magnet or the like.
“Environmental magnetic field”: a magnetic field applied to a transmission line from an initial state, and is a magnetic field generated from terrestrial magnetism or other electronic devices. That is, a magnetic field that becomes noise when measuring an external magnetic field.
"Bias magnetic field": a magnetic field previously applied to a sensor using a coil or the like in order to add polarity to the sensor output or improve linearity.

FIG. 1 is a diagram showing a schematic configuration of a magnetic detection device 1 according to one embodiment. The magnetic detection device 1 includes a transmission line 10, a calculation device 20, a signal generator 30, a connector 40, and a terminating resistor 50.

The transmission line 10 is a linear transmission line. The transmission line 10 has a predetermined characteristic impedance. The transmission line 10 may be configured as, for example, a coaxial cable or FPC (Flexible Printed Circuits). By configuring as a coaxial cable or an FPC, the transmission line 10 can have flexibility and can be easily bent. Since the transmission line 10 has flexibility, it can be freely installed according to the shape of the measurement target.

一端 One end of the transmission line 10 is connected to the connector 40, and the other end is connected to the terminating resistor 50. Since the other end of the transmission line 10 is connected to the terminating resistor 50, almost no reflected wave is generated with respect to the incident wave input from the signal generator 30 via the connector 40. The other end of the transmission line 10 may be connected to an attenuator (attenuator) instead of the terminating resistor 50.

An example in which the transmission line 10 is configured as a coaxial cable will be described with reference to FIG. As shown in FIG. 2, the transmission line 10 includes a first conductor (signal line) 11, a dielectric 12, a second conductor (shield line) 13, and a coating 14.

The first conductor 11 is a linear conductor containing a magnetic material. The first conductor 11 only needs to include a magnetic material on at least the surface, but in the example shown in FIG. 2, the first conductor 11 includes a magnetic material that is distributed substantially uniformly.

The first conductor 11 may include a soft magnetic material having a small coercive force and a high magnetic permeability. The first conductor 11 may include, for example, an amorphous alloy or permalloy.

Amorphous alloys and permalloys include magnetic materials with high magnetic permeability. Therefore, the transmission line 10 including the first conductor 11 has high circumferential magnetic permeability and high axial magnetic permeability. Since the circumferential magnetic permeability and the axial magnetic permeability are high, when an external magnetic field is applied, the transmission line 10 has the effect of the magnetic impedance effect on the surface of the first conductor 11 and the effect of the magnetization (domain wall movement) inside the first conductor 11. The impedance changes due to one or both effects.

For example, amorphous alloys in which atoms are randomly arranged include Fe-based amorphous alloys such as Fe-Co-Si-B alloys (Fe-rich), Fe-Si-BC alloys, Fe-Si-B alloys, and Fe-Si-B alloys. It may be a Si-B-Nb-Cu-based alloy or an Fe-PB-based alloy. Further, the amorphous alloy is a Co-based amorphous alloy such as a Fe-Co-Si-B alloy (Co-rich), a Co-Fe-Cr-Si-B alloy, or a Co-Fe-Mn-Cr-Si-B alloy. A system alloy may be used. Further, the amorphous alloy may be a Ni-based amorphous alloy.

For example, permalloy, which is an alloy mainly composed of Fe and Ni, is 78-permalloy having a Ni content of 78.5% (JIS standard: Permalloy A), and 45-permalloy having a Ni content of 45% (40 to 50%). (JIS standard: Permalloy B) or permalloy obtained by adding Mo, Cu, Cr or the like to 78-permalloy (JIS standard: Permalloy C).

体積 The volume resistivity of Permalloy is about 68 μΩcm. This is 40 times or more the volume resistivity of copper, which is 1.68 μΩcm.

The first conductor 11 is made of an Fe—Si—Al alloy (eg, Sendust), an Fe—Co alloy (eg, permendur), a Mn—Zn alloy, or a Ni—Al—alloy other than an amorphous alloy and permalloy. It may include a -Zn-based alloy (for example, soft ferrite) or an Fe-Si-based alloy (for example, silicon steel or electromagnetic steel).

When the magnetic field applied to the transmission line 10 is a relatively large magnetic field of about 10 [Oe (Oersted)], the first conductor 11 may include a single metal such as Fe, Ni, or Co as a magnetic material.

The first conductor 11 may include a nanocrystalline soft magnetic material in which nanocrystalline grains are dispersed in an amorphous phase.

The dielectric 12 has a cylindrical shape and covers the first conductor 11. The dielectric 12 may be, for example, an insulator such as PTFE (polytetrafluoroethylene) or polyethylene.

The second conductor 13 has a cylindrical shape and covers the dielectric 12. The second conductor 13 may be, for example, a braided wire composed of a copper wire.

The coating 14 has a cylindrical shape and covers the second conductor 13. The coating 14 protects the first conductor 11, the dielectric 12, and the second conductor 13 housed therein.

The first conductor 11, the dielectric 12, the second conductor 13, and the coating 14 may be made of a flexible material. Thereby, the transmission line 10 can have flexibility.

The arithmetic unit 20 detects a voltage pulse (hereinafter, also simply referred to as a “pulse”) input from the signal generator 30 via the connector 40 as an incident wave. The arithmetic unit 20 detects a pulse input from the transmission line 10 via the connector 40 as a reflected wave. Details of the reflected wave generated in the transmission line 10 will be described later.

The arithmetic unit 20 includes an input circuit 21, an AD converter (ADC) 22, a control unit 23, and a memory 24, as shown in FIG.

The input circuit 21 detects an incident wave input from the signal generator 30 through the connector 40. The input circuit 21 detects a reflected wave input from the transmission line 10 via the connector 40. The input circuit 21 includes an attenuation circuit, a preamplifier, and the like. The input circuit 21 adjusts the amplitude of the incident wave and the reflected wave input as an analog signal so as to be in a range appropriate for the input specification of the AD converter 22, and outputs the analog signal after the amplitude adjustment to the AD converter 22. I do.

The AD converter 22 converts an analog signal received from the input circuit 21 into digital data and outputs the digital data to the control unit 23.

The control unit 23 controls each component of the arithmetic device 20. The control unit 23 may be configured as a processor such as a CPU (Central Processing Unit), for example. Details of the function of the control unit 23 will be described later.

The memory 24 is connected to the control unit 23. The memory 24 includes, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), an EEPROM (Electrically Erasable Programmable Read-Only Memory, and a ROM (Read-Only Memory), a ROM (Read-Only Memory), and a ROM (Read-Only Memory). It has a storage device. The memory 24 may function as, for example, a main storage device, an auxiliary storage device, or a cache memory. The memory 24 is not limited to the one built in the arithmetic device 20, and may be an external storage device connected via a digital input / output port such as a USB (Universal Serial Bus).

The signal generator 30 generates a voltage pulse. The signal generator 30 is connected to the connector 40. The pulse generated by the signal generator 30 is input to the transmission line 10 via the connector 40 as an incident wave. The pulse generated by the signal generator 30 is branched at the connector 40 and input to the arithmetic unit 20.

The signal generator 30 may generate a short pulse or a pulse with a fast rise time as a pulse. With such a pulse, when the arithmetic device 20 detects a plurality of reflected waves, it becomes easy to separate the plurality of reflected waves. Further, by using such a pulse, the power consumption of the signal generator 30 can be reduced.

The pulse generated by the signal generator 30 is not particularly limited. For example, the rise time may be 200 [ps], the pulse width may be 500 [ps], and the pulse height may be 1 [V].

The pulse generated by the signal generator 30 may have any shape. The pulse generated by the signal generator 30 may be, for example, rectangular, sinusoidal, triangular, or sawtooth.

The connector 40 connects the transmission line 10, the arithmetic unit 20, and the signal generator 30 to each other. The connector 40 may be, for example, a T-type connector.

With reference to FIG. 3, a state where the magnetic detection device 1 detects a magnetic field application position on the transmission line 10 when a magnetic field is applied to the transmission line 10 will be described. In the example shown in FIG. 3, a magnet 60 is arranged near the transmission line 10, and an external magnetic field having a magnetic field strength _Hex generated by the magnet 60 is applied to the transmission line 10.

When an external magnetic field having a magnetic field strength _Hex is applied, the impedance of the transmission line 10 changes due to the magnetic impedance effect at the magnetic field application position where the magnetic field is applied. Hereinafter, the magnetic impedance effect will be described.

(4) The transmission line 10 can be represented as an equivalent distributed constant circuit as shown in FIG. In FIG. 4, L is an inductance component of the first conductor 11 per unit length. R is a resistance component of the first conductor 11 per unit length. C is a capacitance component per unit length between the first conductor 11 and the second conductor 13.

When an external magnetic field having a magnetic field strength _Hex is applied to the transmission line 10, the resistance component R and the inductance component L of the first conductor 11 change at the magnetic field application position where the magnetic field is applied.

When a pulse is input from the signal generator 30, the first conductor 11 of the transmission line 10 is magnetized in one direction in the circumferential direction. Here, the circumferential direction is a direction in which the direction in which the transmission line 10 extends is defined as an axial direction and rotates around the axial direction. In this state, when an external magnetic field having a magnetic field strength H _ex is applied in the axial direction of the transmission line 10 as shown in FIG. 3, the magnetic moment induced in the circumferential direction is applied to the external magnetic field having the magnetic field strength H _ex. Rotate along the direction.

(4) Due to the rotation of the magnetic moment, the magnetic permeability of the first conductor 11 in the circumferential direction changes. Since the impedance of the transmission line 10 depends on the magnetic permeability of the first conductor 11 in the circumferential direction, if the magnetic permeability of the first conductor 11 at the magnetic field application position changes, the impedance of the transmission line 10 at the magnetic field application position changes. I do.

The magnetic impedance effect is expressed by the following equation (1) when the skin effect is remarkable (skin depth δ << radius a of the first conductor 11).

Here, Z is the impedance of the transmission line 10, ω is the angular frequency when a pulse is approximated as a sine wave, a is the radius of the first conductor 11, ρ is the electrical resistivity of the first conductor 11, and R _DC is the DC resistance. , Μ is the magnetic permeability of the first conductor 11 in the circumferential direction, and H _ex is the magnetic field strength of the external magnetic field applied to the transmission line 10. To explain ω in more detail, the pulse waveform can be approximated by a sine wave having a time width of −T / 2 to T / 2 (T is the period of the sine wave). At this time, the pulse whose peak voltage is V has a waveform obtained by adding a V / 2 offset to a sine wave having an amplitude of V / 2. Therefore, the rise time of the pulse _{t r ≒ T / 2 = 1} / (2f) , and becomes an angular frequency omega = 2 [pi] f. The approximation of a pulse as a sine wave is an example, and may be approximated by another waveform.

Referring to equation (1), it can be seen that when the magnetic permeability μ of the first conductor 11 in the circumferential direction changes, not only the inductance component L but also the resistance component R changes.

As shown in FIG. 3, when an external magnetic field having a magnetic field strength _Hex is applied to the transmission line 10 by the magnet 60, the impedance of the transmission line 10 changes at the magnetic field application position. Therefore, when a pulse is input as an incident wave from the signal generator 30 to the transmission line 10 in this state, a reflected wave is generated at the magnetic field application position due to impedance mismatch at the magnetic field application position.

反射 The reflected wave generated at the magnetic field application position travels in the transmission line 10 in the direction opposite to the incident wave, and is input to the arithmetic unit 20 via the connector 40.

Therefore, the time difference Δt between the time when the arithmetic device 20 detects the incident wave and the time when the reflected wave is detected is the time that the reflected wave reciprocates between the connector 40 and the magnetic field application position. Therefore, the distance D from the connector 40 to the magnetic field application position is represented by the following equation (2).

Here, _Vp is the propagation speed of the electromagnetic wave in the transmission line 10, α is the wavelength reduction rate in the transmission line 10, and c is the propagation speed of the electromagnetic wave in vacuum.

FIG. 5 shows an example of how the arithmetic unit 20 detects an incident wave and a reflected wave with a time difference Δt.

In Equation (2), the propagation speed c of the electromagnetic wave in vacuum is known as the light speed in vacuum of 3.0 × 10 ⁸ [m / s]. In addition, the wavelength shortening rate α in the transmission line 10 is a value that depends on members constituting the transmission line 10 such as the dielectric 12 and is known. Therefore, the control unit 23 of the arithmetic device 20 can calculate the distance D from the connector 40 to the magnetic field application position based on the time difference Δt between the time for detecting the incident wave and the time for detecting the reflected wave. That is, the control unit 23 of the arithmetic device 20 can calculate the position of the magnetic field applied to the transmission line 10.

Next, calculation of the strength of the magnetic field applied to the transmission line 10 by the magnetic detection device 1 will be described.

As described above, when an external magnetic field having the magnetic field strength _Hex is applied to the transmission line 10, the impedance changes at the magnetic field application position where the magnetic field is applied due to the magnetic impedance effect. In the transmission line 10, when an incident wave advances from a position where impedance is matched to a magnetic field application position where impedance is mismatched, a reflected wave is generated. At this time, the reflectance r of the reflected wave with respect to the incident wave is represented by the following equation (3).

Here, Z _m the impedance in the magnetic field applying position of the transmission line 10, Z ₀ is the characteristic impedance at the position where the impedance of the transmission line 10 are matched, [Delta] Z is the amount of change in the impedance in the magnetic field applying position of the transmission line 10 .

Further, the transmission line 10, from a position where the impedance is matched, the voltage V _R of the reflected wave impedance generated by the incident wave has progressed to the magnetic field application position which is misaligned, the following equation (4 ).

Here, V _i is the voltage of the incident wave.

In Equation (4), the characteristic impedance Z ₀ at the position where the impedance of the transmission line 10 are matched is known. Further, the voltage V _i of the incident wave are known the amplitude of the pulse signal generator 30 generates. Accordingly, the control unit 23 of the computing device 20 based on the voltage V _R of the reflected wave, it is possible to calculate the impedance variation ΔZ in the magnetic field applying position of the transmission line 10.

6 shows a magnetic field applied to the transmission line 10, the relationship between the voltage V _R of the reflected wave. As shown in FIG. 6, when the magnetic field applied to the transmission line 10 is zero, the voltage V _R of the reflected wave is zero. According intensity of the applied magnetic field in the transmission line 10 is increased, the voltage V _R of the reflected wave increases.

Since the change amount ΔZ of the impedance depends on the magnetic field strength _Hex of the external magnetic field applied to the transmission line 10, the control unit 23 of the arithmetic device 20 determines the transmission line 10 based on the change amount ΔZ of the impedance. Can be calculated. More specifically, the magnetic detection device 1, the voltage V _R of the detected reflected wave can be calculated impedance variation ΔZ by substituting the equation (4). The magnetic detection device 1 can calculate the magnetic field strength H _ex applied to the transmission line 10 by substituting Z ₀ + ΔZ into Z in Expression (1). The magnetic detection device 1, when calculating the field strength H _ex, rather than using Equation (1), the magnetic field intensity H _ex using the equation approximating the equation (1) (for example, linear approximation) It may be calculated.

As described above, the magnetic detection device 1 can calculate the distance D from the connector 40 to the magnetic field application position by measuring the time difference Δt between the time for detecting the incident wave and the time for detecting the reflected wave. . Further, the magnetic detection device 1, by measuring the amplitude of the voltage V _R of the reflected wave, can be calculated intensity of the magnetic field applied to the transmission line 10. Therefore, the magnetic detection device 1 can calculate the magnetic field application position on the transmission line 10 and the strength of the magnetic field applied to the transmission line 10 at the same time.

Calculation unit 20, a magnetic field application position in the transmission line 10, when calculating the intensity of the magnetic field applied to the transmission line 10, the difference data obtained by subtracting the offset data from the voltage V _R of the reflected wave, magnetic field applying position And the data of the reflected wave used in calculating the strength of the magnetic field. The arithmetic unit 20 may store, in the memory 24, data detected when no magnetic field is applied to the transmission line 10 as offset data. Calculation unit 20, Thus, by using the difference data obtained by subtracting the offset data from the voltage V _R of the reflected wave, the mechanical tolerances of the components of the transmission line 10, distortions caused by bending or the like of the transmission line 10 And the influence of reflected waves generated by an environmental magnetic field (for example, a magnetic field generated from geomagnetism or electronic equipment) applied from the initial state.

Note that FIG. 3 illustrates the case where the magnet 60 applies an external magnetic field to the transmission line 10, but the type of applying the external magnetic field to the transmission line 10 is not limited to the magnet 60. For example, even when an external magnetic field due to a Helmholtz coil, an external magnetic field due to leakage from a magnetic material, or an external magnetic field generated due to an eddy current is applied to the transmission line 10, the magnetic detection device 1 operates in the transmission line 10. The magnetic field application position and the strength of the magnetic field applied to the transmission line 10 can be calculated simultaneously. Further, the magnetic detection device 1 can measure not only an external magnetic field applied by the magnet 60 or the like but also an environmental magnetic field such as geomagnetism.

Next, with reference to FIGS. 7A to 7C, the reflected wave generated at the magnetic field application position of the transmission line 10 will be described in detail.

FIG. 7A shows a state before the incident wave P1 reaches the magnetic field application position of the transmission line 10. FIG. 7B shows a state when the incident wave P1 enters the magnetic field application position of the transmission line 10. FIG. 7C shows a state where the incident wave P1 passes through the magnetic field application position of the transmission line 10.

伝 送 As shown in FIG. 4, the transmission line 10 can be represented as an equivalent distributed constant circuit. When the pulse passes through the magnetic field application position in the transmission line 10, the resistance component R and the inductance component L of the first conductor 11 at the magnetic field application position change due to the magnetic impedance effect. Therefore, the impedance of the transmission line 10 changes at the position where the magnetic field is applied. Generally, the impedance Z of a distributed constant circuit is represented by the following equation (5).

Here, G is a conductance component corresponding to a leakage resistance per unit length between the first conductor 11 and the second conductor 13, but the conductance component G is omitted because it is very small.

場合 When the skin effect is remarkable (skin depth δ << radius a of the first conductor 11), the impedance Z of the transmission line 10 is expressed by the following equation (6) in consideration of the magnetic impedance effect.

7A is before the incident wave P1 arrives at the magnetic field application position of the transmission line 10, so the incident wave P1 travels in a place where the impedance of the transmission line 10 is constant. Therefore, no reflected wave is generated.

FIG. 7B shows a state when the incident wave P1 enters the magnetic field application position of the transmission line 10. As shown in FIG. 7B, at the magnetic field application position of the transmission line 10, the impedance of the transmission line 10 increases by ΔZ due to the magnetic impedance effect and becomes Z ₀ + ΔZ. In this case, the transmission line 10, the incident wave P1 from a characteristic impedance Z _0, for entering the line impedance Z _{0 +} [Delta] Z, positive reflection wave P2 is generated.

FIG. 7C shows a state where the incident wave P1 passes through the magnetic field application position of the transmission line 10. In Figure 7C, contrary to the state shown in FIG. 7B, the incident wave P1 from the line impedance Z _{0 +} [Delta] Z, for entering the characteristic impedance of Z _0, the negative reflected wave P3 is generated.

と When a magnetic field is applied to the transmission line 10, positive and negative reflected waves are generated at the position where the magnetic field is applied. In the examples shown in FIGS. 7A to 7C, since the length L1 of the magnetic field application position shown in FIG. 7A is longer than the pulse width of the incident wave P1, positive and negative reflected waves are separated.

When calculating the time difference Δt, the arithmetic device 20 may use the peak time of the positive reflected wave P2, but is not limited thereto. The arithmetic unit 20 may use the time of the rise or fall of the positive reflected wave P2. Further, the arithmetic unit 20 may use the peak, rise, or fall time of the negative reflected wave P3. Further, the arithmetic device 20 may calculate the length L1 of the magnetic field application position using the time difference calculated using the positive reflected wave P2 and the time difference calculated using the negative reflected wave P3.

正 Depending on the relationship between the pulse width of the incident wave and the length of the magnetic field application position, there may be a state where the positive and negative reflected waves partially overlap. Such a state is shown in FIGS. 8A to 8C.

FIG. 8A shows a state before the incident wave Q1 reaches the magnetic field application position of the transmission line 10. FIG. 8B shows a state where the incident wave Q1 enters the magnetic field application position of the transmission line 10. FIG. 8C shows a state where the incident wave Q1 passes through the magnetic field application position of the transmission line 10.

8A to 8C, the pulse width of the incident wave Q1 is substantially equal to the length L2 of the magnetic field application position shown in FIG. 8A. Therefore, as shown in FIG. 8C, the positive reflected wave Q2 and the negative reflected wave Q3 partially overlap.

The shape of the pulse generated by the signal generator 30 is arbitrary, but if the rise time is shortened, the position resolution when the arithmetic device 20 detects the magnetic field application position can be increased. Therefore, when there are a plurality of magnetic field application positions described later, the arithmetic unit 20 can clearly separate the plurality of magnetic field application positions. On the other hand, when the rising time of the pulse is increased, the attenuation of the incident wave and the reflected wave is reduced even if the transmission distance of the pulse is increased, so that the arithmetic unit 20 can measure a long distance.

(When there are multiple magnetic field application positions)
In the transmission line 10, if the magnetic field at a plurality of locations is applied, the arithmetic unit 20, the reflected waves generated in each of the plurality of magnetic field application position, detects the voltage V _R of the time difference Δt and the reflected wave. Thereby, the magnetic detection device 1 can simultaneously calculate the magnetic field application position and the magnetic field strength for each of the plurality of magnetic field application positions on the transmission line 10.

(Other examples of coaxial cable)
9A and 9B show another example in which the transmission line 10 is configured as a coaxial cable. The transmission line 10a illustrated in FIG. 9A includes a first conductor (signal line) 11a, a dielectric 12a, a second conductor (shield line) 13a, and a coating 14a. The dielectric 12a, the second conductor 13a, and the coating 14a have the same configuration as the dielectric 12, the second conductor 13, and the coating 14, respectively, shown in FIG.

The first conductor 11a includes a conductor 15a and a magnetic film 16a. The conductor 15a is a non-magnetic conductor. The magnetic film 16a is a film containing a magnetic material, and is formed on the surface of the conductor 15a. The magnetic material included in the magnetic film 16a may be the same magnetic material as the magnetic material included in the first conductor 11 illustrated in FIG.

The magnetic film 16a can be formed on the surface of the conductor 15a by, for example, plating, vapor deposition, sputtering, or CVD (Chemical Vapor Deposition).

Since the conductor 15a is a non-magnetic conductor, the first conductor 11a does not cause impedance change due to magnetization (domain wall movement) inside the first conductor 11a. Therefore, in the first conductor 11a, hysteresis hardly occurs, and a magnetic field can be detected with high sensitivity.

伝 送 The transmission line 10b shown in FIG. 9B includes a plurality of first conductors (signal lines) 11b, a dielectric 12b, a second conductor (shield line) 13b, and a coating 14b. The dielectric 12b, the second conductor 13b, and the coating 14b have the same configuration as the dielectric 12, the second conductor 13, and the coating 14 shown in FIG. 2, respectively.

The configuration of each first conductor 11b of the plurality of first conductors 11b may be the same as the configuration of the first conductor 11 shown in FIG.

こ と By thus configuring the plurality of first conductors 11b in a bundle, the resistance loss of the plurality of first conductors 11b as a whole can be reduced. Therefore, even when the transmission line 10b is long, the attenuation of the incident wave and the reflected wave can be reduced. Therefore, the magnetic detection device 1 includes the long transmission line 10b, and can measure the position and intensity of the applied magnetic field.

(Other examples of transmission lines)
The transmission line 10 does not have to be configured as a coaxial cable as long as the line has a characteristic impedance. For example, the transmission line 10 may be configured as a parallel two line, a strip line, a microstrip line, a coplanar line, or a waveguide. FIGS. 10A to 10D show examples in which the transmission line 10 is not configured as a coaxial cable.

FIG. 10A is a diagram showing a cross section when the transmission line 10c is configured as two parallel lines. The transmission line 10c includes a first conductor (signal line) 11c, a dielectric 12c, and a second conductor (shield line) 13c. The first conductor 11c includes a magnetic material as in the case of the first conductor 11 shown in FIG. The first conductor 11c is formed as a thin film on the dielectric 12c.

FIG. 10B is a diagram showing a cross section when the transmission line 10d is configured as a strip line. The transmission line 10d includes a first conductor (signal line) 11d, a dielectric 12d, and a second conductor (shield line) 13d. The first conductor 11d includes a magnetic material similarly to the first conductor 11 shown in FIG. The first conductor 11d is formed as a thin film inside the dielectric 12d.

FIG. 10C is a diagram showing a cross section when the transmission line 10e is configured as a microstrip line. The transmission line 10e includes a first conductor (signal line) 11e, a dielectric 12e, and a second conductor (shield line) 13e. The first conductor 11e includes a magnetic material as in the case of the first conductor 11 shown in FIG. The first conductor 11e is formed as a thin film on the dielectric 12e.

FIG. 10D is a diagram showing a cross section when the transmission line 10f is configured as a coplanar line. The transmission line 10f includes a first conductor (signal line) 11f, a dielectric 12f, and a second conductor (shield line) 13f. The first conductor 11f includes a magnetic material similarly to the first conductor 11 shown in FIG. The first conductor 11f is formed as a thin film on the dielectric 12f.

The dielectrics 12c to 12f shown in FIGS. 10A to 10D may be, for example, an insulator such as PTFE (polytetrafluoroethylene) or polyethylene, similarly to the dielectric 12 shown in FIG.

The second conductors 13c to 13f shown in FIGS. 10A to 10D may be made of, for example, copper as in the case of the second conductor 13 shown in FIG.

Hereinafter, the magneto-impedance effect in the transmission lines 10c to 10f including the thin film-shaped first conductors 11c to 11f as shown in FIGS. 10A to 10D will be described. Assuming that the thickness of the first conductors 11c to 11f is d, when the skin effect is remarkable (skin depth δ << d / 2), the magnetic impedance effect is expressed by the following equations (7) and (8). expressed.

Here, w is the width of the first conductors 11c to 11f, and l is the length of the first conductors 11c to 11f.

Similarly to the transmission line 10 configured as the coaxial cable shown in FIG. 2, the transmission lines 10c to 10f shown in FIGS. 10A to 10D also rotate in the circumferential direction of the first conductors 11c to 11f due to the rotation of the magnetic moment. The permeability changes. Since the impedance of the transmission lines 10c to 10f depends on the magnetic permeability of the first conductors 11c to 11f in the circumferential direction, when the magnetic permeability of the first conductors 11c to 11f in the magnetic field applying position changes, the transmission at the magnetic field applying position changes. The impedance of the lines 10c to 10f changes.

伝 送 The transmission lines 10c to 10f shown in FIGS. 10A to 10D can be provided with flexibility, for example, by forming the transmission lines 10c to 10f by a flexible substrate, as in the case of being formed by a coaxial cable.

The first conductors 11c to 11f shown in FIGS. 10A to 10D may have a configuration in which a magnetic film is formed on the surface of a nonmagnetic conductor, like the first conductor 11a shown in FIG. 9A.

The transmission lines 10c to 10f shown in FIGS. 10A to 10D may have a configuration including a plurality of first conductors 11c to 11f, similarly to the transmission line 10b shown in FIG. 9B.

(Application of bias magnetic field)
The magnetic detection device 1 may include a coil 70 around the transmission line 10 as shown in FIG. The coil 70 applies a bias magnetic field in the axial direction (longitudinal direction) of the transmission line 10 by flowing a bias current as shown in FIG.

As described above, when the bias magnetic field is uniformly applied to the transmission line 10 by the coil 70 in the positive direction, the characteristic impedance of the transmission line 10 changes from Z ₀ to Z ₁ (Z ₀ <Z ₁ ). relationship between the applied magnetic field and the voltage _{V R} of the reflected wave becomes to be offset to the graph _V R1 _{(H ex)} showing graph _V R0 from _{(H ex)} 12 shown in FIG. In a state where no external magnetic field is applied to the transmission line 10, since the characteristic impedance is uniform in Z _1, no reflected wave. When a positive magnetic field is applied as an external magnetic field, an external magnetic field is applied in addition to the bias magnetic field. Therefore, the characteristic impedance of the magnetic field application unit becomes Z ₁ + ΔZ, and reflected waves as shown in FIGS. 7B and 7C are generated. . When a negative magnetic field is applied as an external magnetic field, the external magnetic field is applied in a direction opposite to the bias magnetic field, so that the characteristic impedance of the magnetic field application unit becomes Z ₁ −ΔZ, and the reflected wave of the opposite phase of FIGS. 7B and 7C. Occurs. Thus, the magnetic detection device 1 can determine not only the strength of the magnetic field applied to the transmission line 10 but also whether a positive magnetic field or a negative magnetic field has been applied. Although the intensity of the bias magnetic field is optional, smaller than the saturation magnetic field (magnetic field in the range indicated by H _s of FIG. 12), such as linearity is improved as a sensor (substantially linearly range indicated by H _sL of 12 Is applied).

According to the magnetic detection device 1 according to the embodiment as described above, it is possible to detect a magnetic field at an arbitrary position in the distributed constant circuit. More specifically, in the magnetic detection device 1, the signal generator 30 inputs a pulse as an incident wave into the transmission line 10, and the arithmetic device 20 determines the reflection caused by impedance mismatch at the magnetic field application position of the transmission line 10. A wave and an incident wave are detected. Then, the arithmetic unit 20 calculates the position and intensity of the magnetic field applied to the transmission line 10 based on the incident wave and the reflected wave. Therefore, the magnetic detection device 1 according to one embodiment can detect a magnetic field at an arbitrary position on the transmission line 10 that can be represented as a distributed constant circuit.

Further, according to the magnetic detection device 1 according to one embodiment, since the magnetic field application position in the transmission line 10 and the intensity of the magnetic field applied to the transmission line 10 can be detected simultaneously, the measurement in the transmission line 10 is performed. A non-uniform external magnetic field generated from an object can be detected. Therefore, the magnetic detection device 1 can measure an external magnetic field generated by a magnetization distribution of a magnetic material to be measured, an external magnetic field generated by a magnetic field distribution due to a defect on a metal surface to be measured, and the like. In addition, the magnetic detection device 1 is applicable to a wide variety of measurement devices such as terrestrial magnetism detection, eddy current flaw detection, a magnetic microscope, a current sensor, and a magnetoencephalograph.

According to the magnetic detection device 1 according to one embodiment, a plurality of magnetic field application positions on the transmission line 10 can be detected. For example, a conventional magnetic sensor such as a Hall element, a magneto-resistance (MR) sensor, a magneto-impedance (MI) sensor, a flux gate, a pickup coil, a SQUID (Superconducting @ Quantum @ Interference @ Device) and an OPAM (OpticalMaterial-Primary-Medical-Pattern) , Point measurement, or small area measurement. Therefore, in order to measure the distribution of the magnetic field, it was necessary to install a plurality of magnetic sensors. Was. On the other hand, the magnetic detection device 1 according to one embodiment can detect a plurality of magnetic field application positions, so that the distribution of the magnetic field can be measured by one device.

Further, according to the magnetic detection device 1 according to one embodiment, the first conductor 11 in the transmission line 10 includes a magnetic material having a high magnetic permeability such as an amorphous alloy or permalloy, so that about 10 m [Oe]. A minute magnetic field can be detected.

(Frequency sweep)
FIG. 13 is a diagram illustrating a schematic configuration of a magnetic detection device 2 according to another embodiment. Regarding the magnetic detection device 2 according to another embodiment, differences from the magnetic detection device 1 shown in FIG. 1 will be mainly described, and the same contents as those of the magnetic detection device 1 shown in FIG. 1 will be appropriately described. Omitted.

The magnetic detection device 2 shown in FIG. 1 is that the data based on the incident wave and the reflected wave is first processed as frequency domain data, and then the frequency domain data is converted into time domain data for processing. This is different from the detection device 1. The processing of the magnetic detection device 2 after converting the frequency domain data into the time domain data for the incident wave and the reflected wave is the same as the processing of the magnetic detection device 1 shown in FIG.

The magnetic detection device 2 includes the measurement device 100, the transmission line 10, and the terminating resistor 50. The transmission line 10 and the terminating resistor 50 may have the same configuration as the transmission line 10 and the terminating resistor 50 shown in FIG.

FIG. 14 shows how the magnetic detection device 2 detects a magnetic field application position on the transmission line 10 when a magnetic field is applied to the transmission line 10. As in the case shown in FIG. 3, when the magnet 60 is arranged near the transmission line 10, an external magnetic field having a magnetic field strength _Hex generated by the magnet 60 is applied to the transmission line 10. When an external magnetic field having a magnetic field strength _Hex is applied, the impedance of the transmission line 10 changes due to the magnetic impedance effect at the magnetic field application position where the magnetic field is applied. In this state, when an incident wave is input from the signal generator 130 to the transmission line 10, a reflected wave is generated at the magnetic field application position due to impedance mismatch at the magnetic field application position.

に Returning to FIG. 13, the description of the magnetic detection device 2 will be continued.

The measuring device 100 includes an arithmetic device 120, a signal generator 130, and a directional coupler 140. The measurement device 100 may be, for example, a measurement device that functions as a vector network analyzer.

The arithmetic unit 120 detects a sinusoidal pulse input from the signal generator 130 as an incident wave. The arithmetic unit 120 may receive the incident wave directly from the signal generator 130 or may receive the incident wave via the directional coupler 140.

The incident wave detected by the arithmetic unit 120 is a sinusoidal pulse that is output by the signal generator 130 sweeping. FIG. 15 shows an example of an incident wave detected by the arithmetic unit 120. In the example shown in FIG. 15, a sinusoidal pulse is continuously swept from a low frequency to a high frequency. Here, the term “sinusoidal pulse” is used to indicate one cycle of a sinusoidal waveform. That is, the “sinusoidal pulse” has both the positive side part and the negative side part of the sinusoidal waveform. In the example shown in FIG. 15, the sinusoidal pulse is swept so as to smoothly change from a low frequency to a high frequency, but the waveform of the incident wave is not limited to this. The waveform of the incident wave may be, for example, a waveform in which the frequency of the sine wave pulse is switched every one cycle or every N cycles.

The arithmetic unit 120 detects a pulse input from the transmission line 10 via the directional coupler 140 as a reflected wave.

The signal generator 130 generates a sinusoidal pulse. The signal generator 130 sweeps and outputs a sine wave pulse. The sinusoidal pulse that is swept and output by the signal generator 130 has, for example, a waveform as shown in FIG. Here, “sweeping and outputting” means outputting while changing the frequency of the sinusoidal pulse. The signal generator 130 may output a sinusoidal pulse while changing the frequency from, for example, 10 MHz to 50 GHz.

The signal generator 130 is connected to the signal detector 121 of the arithmetic unit 120 and the directional coupler 140. The sinusoidal pulse swept and output by the signal generator 130 is input to the transmission line 10 as an incident wave via the directional coupler 140. Further, a sine-wave-like pulse that is swept and output by the signal generator 130 is input to the signal detector 121 of the arithmetic device 120.

The -directional coupler 140 connects the transmission line 10, the arithmetic unit 120, and the signal generator 130 to each other. An incident wave from the signal generator 130 is input to the transmission line 10 via the directional coupler 140. The reflected wave from the transmission line 10 is input to the signal detector 121 of the arithmetic device 20 via the directional coupler 140. The reflected wave from the transmission line 10 is a reflected wave generated with respect to the incident wave due to impedance mismatch at the magnetic field application position of the transmission line 10.

Next, each functional block of the arithmetic device 120 will be described. The arithmetic device 120 includes a signal detector 121, a control unit 122, and a memory 123.

The signal detector 121 detects an incident wave input from the signal generator 130 and a reflected wave input from the directional coupler 140. The signal detector 121 detects the vector ratio of the reflected wave to the incident wave for each frequency of the sinusoidal pulse that is swept and output by the signal generator 130. The vector ratio here is a vector defined by the reflectance and the phase difference of the reflected wave with respect to the incident wave. Here, the reflectance of the reflected wave with respect to the incident wave is obtained by dividing the amplitude of the reflected wave by the amplitude of the incident wave. Further, the phase difference of the reflected wave with respect to the incident wave is obtained by subtracting the phase of the incident wave from the phase of the reflected wave.

Here, for example, the sinusoidal pulse that the signal generator 130 sweeps and outputs as an incident wave may have a constant amplitude with respect to the frequency. Figure 16 shows relative frequencies, how the amplitude is constant V _0.

The signal detector 121 detects, for each frequency, a reflected wave with respect to an incident wave having a frequency characteristic as shown in FIG. 16, and detects the reflectance of the reflected wave with respect to the incident wave and the phase difference of the reflected wave with respect to the incident wave. I do. As described above, the signal detector 121 detects the reflectance and the phase difference of the reflected wave with respect to the incident wave as relative values. Therefore, even if the incident wave has fluctuation, the signal detector 121 can cancel the fluctuation and detect the reflectance and the phase difference of the reflected wave with respect to the incident wave. That is, the signal detector 121 can remove the jitter of the incident wave, and can perform synchronized measurement without temporal signal fluctuation.

The signal detector 121 includes a filter whose pass band is variable (for example, a band-pass filter or an IF (Intermediate Frequency) filter). When the filter is a band pass filter, the pass band of the band pass filter is controlled according to a command from the control unit 122. The control unit 122 controls the pass band of the band-pass filter so that the sinusoidal pulse output from the signal generator 130 is passed and signals of other frequencies are attenuated. Accordingly, the bandpass filter included in the signal detector 121 can attenuate noise in a frequency band other than the sinusoidal pulse output from the signal generator 130 among the noises included in the reflected wave. Therefore, the signal detector 121 can improve the SN ratio of the reflected wave received by the arithmetic device 120.

It is not essential that the signal detector 121 includes a band-pass filter. The signal detector 121 may not include a bandpass filter.

The signal detector 121 may have the same function as the input circuit 21 shown in FIG. The signal detector 121 may have the same function as the AD converter 22 shown in FIG.

The signal detector 121 may detect an incident wave and a reflected wave in a state of an analog signal, or may detect an incident wave and a reflected wave in a state of a digital signal.

The control unit 122 controls each component of the arithmetic device 120. The control unit 122 may be configured as a processor such as a CPU, for example. Details of the function of the control unit 122 will be described later.

The memory 123 is connected to the control unit 122. The memory 123 has an arbitrary storage device such as an HDD, an SSD, an EEPROM, a ROM, and a RAM. The memory 123 may function as, for example, a main storage device, an auxiliary storage device, or a cache memory. The memory 123 is not limited to the one built in the arithmetic unit 120, and may be an external storage device connected via a digital input / output port such as a USB.

The control unit 122 acquires the amplitude and the phase difference of the reflected wave with respect to the incident wave from the signal detector 121 for each frequency of the incident wave. The control unit 122 generates frequency domain data of the reflectance based on the amplitude of the reflected wave with respect to the incident wave. The control unit 122 generates frequency domain data of the phase difference based on the phase difference of the reflected wave with respect to the incident wave. The control unit 122 performs inverse Fourier transform on the frequency domain data of the reflectance and the frequency domain data of the phase difference to generate time domain data of the reflected wave.

The control unit 122 performs the same processing on the time domain data of the reflected wave as the processing performed on the incident wave and the reflected wave by the magnetic detection device 1 shown in FIG. Calculate the position and intensity of.

When calculating the magnetic field application position in the transmission line 10 and the strength of the magnetic field applied to the transmission line 10, the arithmetic device 120 calculates difference data obtained by subtracting offset data from data of a reflected wave detected at the time of applying the magnetic field, It may be used as reflected wave data used when calculating the magnetic field application position and the magnetic field strength. The arithmetic unit 120 may store the data of the reflected wave detected in a state where the magnetic field is not applied to the transmission line 10 in the memory 123 as offset data. At this time, the arithmetic unit 120 uses the data of the reflectance and the phase difference detected in a state where no magnetic field is applied to the transmission line 10 as the frequency domain data of the reflectance and the offset data of the frequency domain data of the phase difference in the memory 123. May be stored in the memory 123 as offset data of the time domain data of the reflected wave.

The arithmetic unit 120 uses the difference data obtained by subtracting the offset data from the data of the reflectance and the phase difference detected when the magnetic field is applied, thereby obtaining the mechanical tolerance of the components of the transmission line 10 and the transmission line 10. Due to bending caused by bending, etc., an environmental magnetic field applied from an initial state (for example, a terrestrial magnetism or a magnetic field generated from an electronic device), and impedance mismatch between transmission lines (for example, a 50Ω coaxial cable and the transmission line 10). The effect of the generated reflected wave can be reduced.

Hereinafter, the processing of the arithmetic unit 120 will be described using an example in which the arithmetic unit 120 uses difference data obtained by subtracting offset data from reflectance and phase difference data detected when a magnetic field is applied.

The control unit 122 controls the signal generator 130 in a state where no magnetic field is applied to the transmission line 10 to sweep and output a sinusoidal pulse as an incident wave. The frequency characteristic of the sinusoidal pulse swept and output by the signal generator 130 may have the amplitude characteristic shown in FIG.

The control unit 122 controls the frequency domain data of the reflectance and the frequency domain data of the phase difference when the signal generator 130 sweeps and outputs a sine wave pulse in a state where no magnetic field is applied to the transmission line 10. Is generated from the incident wave input via the signal detector 121 and the reflected wave input via the directional coupler 140 and the signal detector 121.

The control unit 122 performs inverse Fourier transform on the frequency domain data of the reflectance and the frequency domain data of the phase difference to convert the frequency domain data of the reflected wave into the time domain data of the reflected wave. When the reflectance and the phase difference of the reflected wave with respect to the incident wave have frequency characteristics as shown in FIGS. 17A and 17B, the time domain data of the reflected wave is an impulse response to the incident wave as an impulse signal. The control unit 122 may convert the impulse signal into a step signal by integrating the impulse signal with respect to time. In this case, the time domain data of the reflected wave is a step response to the incident wave as a step signal.

の 一 An example of the reflectance of the reflected wave with respect to the incident wave acquired by the control unit 122 in a state where no magnetic field is applied to the transmission line 10 is, for example, data as indicated by a broken line 202 in FIG. 17A. An example of the phase difference of the reflected wave with respect to the incident wave acquired by the control unit 122 when no magnetic field is applied to the transmission line 10 is, for example, data as indicated by a broken line 204 in FIG. 17B.

Next, the control unit 122 controls the signal generator 130 in a state where the magnetic field is applied to the transmission line 10 to sweep and output a sinusoidal pulse as an incident wave. At this time, the waveform of the incident wave output by the signal generator 130 is the same as the waveform of the incident wave output by the signal generator 130 in a state where no magnetic field is applied to the transmission line 10.

The control unit 122 converts the frequency domain data of the reflectance and the frequency domain data of the phase difference when the signal generator 130 sweeps and outputs a sine wave pulse in a state where the magnetic field is applied to the transmission line 10. , From the incident wave input via the signal detector 121 and the reflected wave input via the directional coupler 140 and the signal detector 121.

An example of the reflectance of the reflected wave with respect to the incident wave acquired by the control unit 122 in a state where the magnetic field is applied to the transmission line 10 is, for example, data as shown by a solid line 201 in FIG. 17A. An example of the phase difference of the reflected wave with respect to the incident wave acquired by the control unit 122 with the magnetic field applied to the transmission line 10 is, for example, data as shown by a solid line 203 in FIG. 17B.

The control unit 122 performs an inverse Fourier transform on the frequency domain data of the reflectance and the frequency domain data of the phase difference acquired in a state where no magnetic field is applied to the transmission line 10, and converts the data into time domain data of the reflected wave. An example of time domain data of a reflected wave in a state where no magnetic field is applied to the transmission line 10 is, for example, data as indicated by a broken line 206 in FIG. 18A. The impulse signal on the vertical axis which is observed as a reflected wave in FIG. 18A is due to impedance mismatch between transmission lines (for example, a 50Ω coaxial cable and the transmission line 10).

The control unit 122 performs an inverse Fourier transform on the frequency domain data of the reflectance and the frequency domain data of the phase difference acquired in a state where the magnetic field is applied to the transmission line 10 to convert the frequency domain data of the reflected wave into the time domain data of the reflected wave. An example of time domain data of a reflected wave in a state where a magnetic field is applied to the transmission line 10 is, for example, data as shown by a solid line 205 in FIG. 18A.

The control unit 122 may integrate the time domain data of the reflected wave as shown in FIG. 18A. An example of data obtained by integrating the time domain data of the reflected wave in a state where no magnetic field is applied, that is, the data shown by the broken line 206 in FIG. 18A is the data shown by the broken line 208 in FIG. 18B. An example of data obtained by integrating the time domain data of the reflected wave in the state where the magnetic field is applied, that is, the data shown by the solid line 205 in FIG. 18A is the data shown by the solid line 207 in FIG. 18B. The step signal observed as a reflected wave in FIG. 18B is due to, for example, impedance mismatch between transmission lines (for example, a 50Ω coaxial cable and the transmission line 10), and the vertical axis observed as a reflected wave in FIG. 18A. This is data obtained by integrating the above impulse signal.

デ ー タ Here, data 208 shown in FIG. 18B is offset data. The controller 122 integrates the time domain data of the reflected wave in the state where the magnetic field is applied, that is, the data obtained by integrating the offset data, that is, the difference data obtained by subtracting the data 208 shown in FIG. 18B from the data 207 shown in FIG. 18B. Is calculated. The calculated difference data obtained by subtracting the offset data is shown as a solid line 209 in FIG. 18C. As shown in FIG. 18C, by subtracting the offset data, it is possible to reduce the influence of impedance mismatch between transmission lines (for example, a 50Ω coaxial cable and the transmission line 10).

The control unit 122 can calculate the position and intensity of the magnetic field by using the data as shown in FIG. 18C as the time domain data of the reflected wave and performing the same processing as that of the magnetic detection device 1 shown in FIG.

The control unit 122 performs a convolution integration process in the frequency domain and then performs an inverse Fourier transform on the frequency domain data of the reflectance and the frequency domain data of the phase difference, instead of performing the inverse Fourier transform and then performing the integration process. Is also good. Accordingly, the control unit 122 can reduce the time required for the calculation as compared with the case where the inverse Fourier transform is performed and then the integration process is performed.

Note that the process of integrating the time domain data of the reflected wave as shown in FIG. 18B is not essential, and the control unit 122 calculates the difference data obtained by subtracting the data 206 from the data 205 shown in FIG. The position and intensity of the magnetic field may be calculated using the region data.

制 御 In addition, the control unit 122 does not have to perform the process of subtracting the offset data and calculating the difference data. In this case, the control unit 122 may calculate the position and intensity of the magnetic field using the time domain data of the reflected wave in the state where the magnetic field is applied.

Note that S11, which is the reflectance in the forward direction, is used as the S parameter (Scattering @parameter) in the two-port pair circuit (four-terminal network), but S22, which is the reflectance in the reverse direction, may be used. Here, S11 means a signal reflected on one terminal when a signal is input from one terminal, and S22 means a signal reflected on the other terminal when a signal is input from the other terminal. .

It will be apparent to those skilled in the art that the present disclosure can be realized in other predetermined forms other than the above-described embodiments without departing from the spirit or essential features thereof. Accordingly, the foregoing description is by way of example and not limitation. The scope of the disclosure is defined by the appended claims, not by the foregoing description. Some of the changes that come within their equivalents are embraced therein.

For example, the arrangement and number of the above-described components are not limited to the above description and the contents shown in the drawings. The arrangement and number of the components may be arbitrarily configured as long as the function can be realized.

1, 2 Magnetic detection device 10, 10a, 10b, 10c, 10d, 10e, 10f Transmission line 11, 11a, 11b, 11c, 11d, 11e, 11f First conductor (signal line)
12, 12a, 12b, 12c, 12d, 12e, 12f Dielectric 13, 13a, 13b, 13c, 13d, 13e, 13f Second conductor (shield wire)
14, 14a, 14b Coating 15a Conductor 16a Magnetic film 20 Arithmetic unit 21 Input circuit 22 AD converter (ADC)
Reference Signs List 23 control unit 24 memory 30 signal generator 40 connector 50 terminator 60 magnet 70 coil 100 measuring device 120 arithmetic unit 121 signal detector 122 control unit 123 memory 130 signal generator 140 directional coupler

Claims (14)

1. A transmission line including a linear first conductor including a magnetic material;
   A signal generator that inputs a pulse as an incident wave to the transmission line,
   A reflected wave generated due to impedance mismatch at a magnetic field application position of the transmission line, and an arithmetic device that detects the incident wave,
   The magnetic detection device, wherein the arithmetic device calculates a position and an intensity of a magnetic field applied to the transmission line based on the incident wave and the reflected wave.
2. The magnetic detection device according to claim 1,
   The magnetic detection device, wherein the arithmetic device calculates a position of a magnetic field applied to the transmission line based on a difference between a time when the incident wave is detected and a time when the reflected wave is detected.
3. The magnetic detection device according to claim 1 or 2,
   The magnetic detection device, wherein the arithmetic device calculates an intensity of a magnetic field applied to the transmission line based on an amplitude of the reflected wave.
4. The magnetic detection device according to any one of claims 1 to 3,
   The arithmetic unit includes:
   Detecting data in a state where no magnetic field is applied to the transmission line as offset data,
   A magnetic detection device, wherein data of a difference obtained by subtracting the offset data from data of a reflected wave in a state where a magnetic field is applied to the transmission line is used as reflected wave data for calculating a position and an intensity of the magnetic field.
5. The magnetic detection device according to any one of claims 1 to 4,
   The transmission line,
   Further comprising a dielectric and a second conductor,
   A magnetic detection device, which is one of a coaxial cable, a parallel two line, a strip line, a microstrip line, a coplanar line, and a waveguide.
6. The magnetic detection device according to any one of claims 1 to 5,
   A magnetic detection device according to claim 1, wherein the first conductor has a magnetic material substantially uniformly distributed, or a magnetic film containing the magnetic material is formed on the conductor surface.
7. The magnetic detection device according to any one of claims 1 to 6,
   The magnetic detection device, wherein the transmission line includes a plurality of the first conductors.
8. The magnetic detection device according to any one of claims 1 to 7,
   A magnetic detection device further comprising a coil for applying a bias magnetic field to the transmission line.
9. The magnetic detection device according to any one of claims 1 to 8,
   The magnetic detection device, wherein the pulse has any one of a rectangular waveform, a sine waveform, a triangular waveform, and a sawtooth waveform.
10. The magnetic detection device according to any one of claims 1 to 8,
    The signal generator sweeps a sinusoidal pulse as the incident wave and inputs the pulse to the transmission line,
    The arithmetic unit includes:
    For each frequency of the input wave that has been input by sweeping, to obtain the amplitude and phase difference of the reflected wave with respect to the incident wave,
    Generate frequency domain data of reflectivity based on the amplitude of the reflected wave for the incident wave,
    Generate frequency domain data of the phase difference based on the phase difference of the reflected wave with respect to the incident wave,
    Magnetic field detection for generating the time domain data of the reflected wave by performing an inverse Fourier transform of the frequency domain data of the reflectance and the frequency domain data of the phase difference, and calculating the position and intensity of the magnetic field applied to the transmission line; apparatus.
11. The magnetic detection device according to claim 10,
    The signal generator sweeps the sinusoidal pulse and inputs the pulse to the transmission line,
    The arithmetic unit generates the time domain data of the reflected wave as an impulse response by performing an inverse Fourier transform on the frequency domain data of the reflectance and the frequency domain data of the phase difference, or the inverse Fourier transformed reflection A magnetic detection device that integrates frequency domain data of a ratio and frequency domain data of the phase difference to generate time domain data of the reflected wave as a step response.
12. The magnetic detection device according to claim 10,
    The signal generator sweeps the sinusoidal pulse and inputs the pulse to the transmission line,
    The arithmetic unit performs a convolution integration process on the frequency domain data of the reflectance and the frequency domain data of the phase difference, performs an inverse Fourier transform, and generates time domain data of the reflected wave as a step response. apparatus.
13. A transmission line used for detecting a magnetic field,
    A transmission line comprising a signal line in which a magnetic material is substantially uniformly distributed or a magnetic film containing the magnetic material is formed on a conductor surface.
14. A transmission line including a linear first conductor including a magnetic material, a signal generator, and an arithmetic unit, the method for detecting magnetic field in a magnetic detection device,
    The signal generator inputs a pulse as an incident wave to the transmission line,
    The arithmetic unit detects a reflected wave generated due to impedance mismatch at a magnetic field application position of the transmission line, and the incident wave,
    Calculating the position and intensity of a magnetic field applied to the transmission line based on the incident wave and the reflected wave.
    

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