JPH07248365A - Magnetism-magnetic direction sensor and magnetism-magnetic direction measuring method - Google Patents

Abstract

PURPOSE:To provide a magnetism sensor which has sufficient accuracy to detect the earth magnetism and can be incorporated into a device in a small type, a magnetic direction sensor and an earth magnetism measuring method using these sensors. CONSTITUTION:A magnetism detecting part 3 is composed of amorphous magnetic substance wires 1 and coils 2 to apply bias magnetic fields to the wires 1, and a magnetism sensor is composed of a pair of magnetism detecting parts arranged in parallel to each other. A magnetic direction sensor is composed of a magnetic direction detecting part constituted by orthogonally arranging two sets or three sets of magnetism sensors. When the earth magnetism is measured, a high frequency electric current of 10k to 30MHz is carried to the respective wires 1, and the bias magnetic fields whose sizes are equal to each other and directions are opposite to each other are generated in a pair of coils, and wire across terminal voltage is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for detecting a weak magnetic field such as geomagnetism and measuring the strength, direction and direction of the weak magnetic field, a magnetic direction sensor and a magnetic measuring method using the magnetic sensor. The present invention relates to an azimuth measuring method.
In the following description, the magnetic field strength means the total magnetic force in the case of geomagnetism, and the direction means the one-dimensional direction.

[0002]

2. Description of the Related Art Conventionally, for example, geomagnetism (tens of thousands nT, tens of A)
The fluxgate type magnetic sensor is most often used as a magnetic direction sensor that accurately detects / m). The fluxgate type magnetic sensor measures the magnetic field by utilizing the fact that the symmetrical BH saturation characteristic of a high permeability magnetic core such as Permalloy changes with an external magnetic field, and has an azimuth measurement accuracy of ± 1 °. . However, the fluxgate magnetic sensor for geomagnetic detection requires a large magnetic core for the reason of principle, and it is impossible to reduce the size and shape of the entire sensor. Magnetic sensors other than the fluxgate type magnetic sensor include a Hall element using a semiconductor, a magnetoresistive element using a magnetic substance (hereinafter, a ferromagnetic substance is simply referred to as a magnetic substance) thin film, and the like. However, although they are small in size and shape, their sensitivity to a magnetic field is not sufficiently accurate to detect geomagnetism by one digit, and geomagnetism cannot be accurately detected.

[0003]

In view of the above-mentioned circumstances, the present invention has a sufficient accuracy for detecting geomagnetism, is small in size, and is easy to install in a device, and a magnetic direction. It is an object of the present invention to provide a sensor and a method of measuring magnetism and magnetic azimuth using these magnetic sensor and magnetic azimuth sensor.

[0004]

The magnetic sensor of the present invention comprises:
A magnetic detection unit is configured to include an amorphous magnetic wire and a coil or a permanent magnet that applies a bias magnetic field to the amorphous magnetic wire, and a pair of the magnetic detection units are arranged in parallel to each other. I am trying. Further, the magnetic azimuth sensor of the present invention is characterized by including a magnetic azimuth detecting unit configured by arranging two sets or three sets of the above-described magnetic sensors so as to be orthogonal to each other.

In the magnetic measuring method of the present invention, a magnetic detecting section is constituted by an amorphous magnetic wire and a coil or a permanent magnet for applying a bias magnetic field to the amorphous magnetic wire, and a pair of the magnetic detecting sections are parallel to each other. A high-frequency current is applied to each of the amorphous magnetic wires of the magnetic sensor configured by arranging them, and a pair of coils or permanent magnets generate bias magnetic fields of equal strength and opposite directions. It is characterized in that the strength and direction of the magnetic field in the longitudinal direction of the magnetic detection unit are measured by detecting the voltage difference between both ends.

Further, the magnetic azimuth measuring method of the present invention is provided with the above-mentioned magnetic sensor, and each set of the magnetic azimuth detecting section constituted by arranging two or three sets of the magnetic sensors so as to be orthogonal to each other. A high-frequency current is applied to each of the amorphous magnetic wires, and a pair of coils or permanent magnets generate bias magnetic fields of equal strength and opposite directions, and the difference between the voltages across the amorphous magnetic wires of each set is detected. Then, the strength and direction of the magnetic field in the longitudinal direction of the magnetic detection units of each set are measured, and these are combined to measure the strength and direction of the magnetic field. Further, the magnetic measuring method and the magnetic azimuth measuring method of the present invention are characterized in that the frequency of the high-frequency current described above is 10 kHz to 30 MHz, respectively.

[0007]

FIG. 1 shows an example of the circuit configuration of the magnetic sensor according to the present invention. The operation will be described with reference to FIG. In the figure, 1 is an amorphous magnetic material wire (hereinafter may be abbreviated as a-wire), 2 is a coil for applying a bias magnetic field to the amorphous magnetic material wire 1, and 3 is an amorphous magnetic material wire 1 and a coil 2. Magnetic detectors configured, 4
Is a resistor, 5 is a high frequency power source for supplying a high frequency current to the amorphous magnetic wire 1, 6 is an amplifier, 7 is a detector, 8 is a low-pass filter, and 9 is a differential amplifier. The two magnetic detectors 3 form a pair and are arranged in parallel with each other to form a magnetic sensor.

The amorphous magnetic wire 1 used in the present invention is formed into a linear wire having a circular cross section by melting an alloy of CoSiB type, FeCoSiB type, or any other composition and then liquid quenching. Further, tension annealing is performed to adjust the magnetostriction constant λ _s and the magnetic anisotropy, and it has a strong magnetic anisotropy in the circumferential direction of the a-wire. As for the magnetostriction constant λ _s , when the absolute value of the magnetostriction constant λ _s becomes smaller than 10 ^{−6, the} voltage across the wire, which will be described later, becomes small and it becomes difficult to detect. Therefore, in the range of −10 ⁻⁶ <λ _s ≦ 0. It is desirable to use one. The diameter of the amorphous magnetic wire 1 is preferably in the range of 10 μ to 150 μ because the detection sensitivity is high, and the length can be used from about 1 mm or more, but it is preferably 3 mm or more from the viewpoint of easy output.

In the above, a known coil or a known permanent magnet, or a combination of a known coil and a known permanent magnet is used to apply the bias magnetic field. Also,
Although it depends on the material of the amorphous magnetic wire 1 and the structure of the magnetic sensor, the frequency f of the high-frequency current applied to the amorphous magnetic wire 1 is preferably in the range of 10 kHz to 30 MHz in order to efficiently extract the change in the inductance. . This is because the sensitivity to the magnetic field is significantly reduced outside the range of 10 kHz to 30 MHz.

The reason why the frequency f of the high-frequency current passing through the amorphous magnetic wire 1 is limited to the range of 10 kHz to 30 MHz will be additionally described with reference to the document co-authored by one of the inventors of the present invention. . "The Institute of Electrical Engineers of Japan Material (Magnetics Workshop MAG-93-2
16-223) "[The Institute of Electrical Engineers of Japan, 1993 1
1993-19]] MAG-93-219 (Page 39-
(Page 48) "Magnetic impedance effect of amorphous magnetic wire", for example, page 44, 4th line to 10th page
Description of the row, as shown in FIG. 6, "ΔE _W / E _W -f characteristic diagram" of 44 pages
Etc. is one basis.

FIG. 6 of the cited document shows the reduction rate Δ of the voltage across the wire with respect to the excitation frequency f when an external magnetic field H _ex is applied.
Shows the E _W / E _W. From this figure, the frequency f of the high frequency current to be passed through the amorphous magnetic wire is 10
It can be seen that the frequency is from kHz to 30 MHz. The desirable range of the frequency f of the high-frequency current depends on the composition, manufacturing method, and shape of the amorphous magnetic wire, but ΔE _W /
It is necessary that E _W is 0.1 or more. For example, 3
Fe with a diameter of 50μ annealed under a tension of kg / mm ^2.
In the case of a CoSiB-based amorphous magnetic wire, a desirable range of frequency f of high frequency current is 80 kHz to 20.
MHz. Further, in the case of a FeCoSiB type amorphous magnetic wire having a diameter of 30 μ annealed under a tension of ² kg / mm ² , a desirable range of the frequency f of the high frequency current is 300 kHz to 25 MHz. And, the amorphous magnetic wire has been improved, and ΔE _W / E
_If an improved _W- f characteristic appears, the frequency f of the high-frequency current passing through the amorphous magnetic wire is 10k.
It is speculated that it will expand from the range of Hz to 30 MHz.

When a high-frequency current is supplied from the high-frequency power source 5 in the longitudinal direction of such an amorphous magnetic wire 1, a voltage across the wire is generated in the a-wire 1, and
A circumferential magnetic field H ₀ is generated around the a-wire 1. At this time, since the a-wire 1 is a magnetic material, it has a self-inductance L that exhibits self-inductivity to prevent a change in current.
Here, when an external magnetic field H _ex is applied in the longitudinal direction of the amorphous magnetic wire 1, the magnetization vector M of the a-wire 1 by an angle ψ (0 ° <ψ <90 °) according to the strength of the external magnetic field H _ex. Tilts. As a result, the effective magnetization component in the circumferential direction that acts as an inductance is M · cosψ (0 <co
Since sψ <1), the self-inductance L decreases. From the change in the self-inductance L, the strength of the external magnetic field H _ex applied in the longitudinal direction of the amorphous magnetic wire 1 can be detected, and conversely, the change in the self-inductance L is caused by the high frequency current in the longitudinal direction of the amorphous magnetic wire 1. It is obtained from the change in the voltage across the wire when electricity is applied to the wire.

In FIG. 2, an external magnetic field H _ex (A / m) is applied in the longitudinal direction of the amorphous magnetic wire 1 to generate a high frequency power supply 5.
2 shows a basic circuit for measuring the voltage (mAp-p) across the wire when a high-frequency current from A is applied to both ends of the a-wire 1. The composition is (Fe ₆ Co ₉₄ ).
_An external magnetic field H _ex (A / m) when the resistance 4 having a resistance value of 100Ω is arranged in series on the amorphous magnetic wire 1 of _72.5 Si _12.5 B ₁₅ and the frequency of the high frequency current is 300 kHz
The change in voltage across the wire (mVp-p) with respect to
Is shown in the graph.

The graph of FIG. 3 shows that the external magnetic field H _ex ± 200
In the vicinity of (A / m), the voltage across the wire has the maximum value and is bilaterally symmetrical with the external magnetic field H _ex 0 as a boundary. The state of the curve of the graph differs depending on the material and shape of the amorphous magnetic wire 1, the frequency of the high-frequency current to be applied, etc., but in both cases, the ordinate axis in the magnetic field 0 (A / m) is taken as the axis of symmetry, and the state of FIG. It will be a symmetrical curve such as a bimodal type or a mountain type. In the curved state of the graph of FIG. 3, the direction of the external magnetic field H _ex cannot be known from the voltage across the wire, and when the voltage across the wire is 55 mVp-p or higher, the strength of the external magnetic field H _ex becomes multivalued. Not determined, external magnetic field H
Cannot detect _ex .

Therefore, the magnetic sensor of the present invention has a magnetic detecting portion 3 including an amorphous magnetic wire 1 and a coil 2 for applying a bias magnetic field to the amorphous magnetic wire 1.
The two magnetic detection units 3 form a pair and are arranged in parallel with each other. Then, each of the amorphous magnetic wires 1 has a frequency of 10 kHz to 30
A coil 2 that carries a high-frequency current of MHz and forms a pair
To generate a bias magnetic field having the same strength in the opposite direction and diametrically opposite to each other, and detecting the difference between the voltage across the wires of each amorphous magnetic wire 1 to detect the external magnetic field H _{ex in} the longitudinal direction of the magnetic detection unit 3.
I tried to find the strength and direction of. That is, in FIG. 3, for example, a bias magnetic field of −500 A / m, +
If it is 500 A / m, +200 A / m to +500 A /
m and curves in the range of -200 A / m to -500 A / m are available, and the strength and direction of the external magnetic field H _ex can be measured in the range of ± 300 A / m if the difference between the voltage across the pair of wires is obtained. can do.

FIG. 4 is a block diagram of the magnetic azimuth detecting section of the magnetic azimuth sensor according to the present invention in the case of a two-component sensor.
The xy coordinate axes are also shown for the purpose of explaining the operation. The magnetic azimuth detecting unit of the magnetic azimuth sensor according to the present invention is arranged so that two sets (in the case of a two-component sensor) or three sets (in the case of a three-component sensor) of the magnetic detecting units in the above-described magnetic sensor are orthogonal to each other. Is configured. In the case of FIG. 4, the magnetic azimuth detecting unit 10 of the magnetic azimuth sensor is configured by arranging the magnetic detecting units 3x and 3y of the magnetic sensor so as to be orthogonal to each other. If the output value of the magnetic detection unit 3x is X and the output value of the magnetic detection unit 3y is Y, the magnetic field strength F and the angle of deviation (deviation angle) θ from the x-axis shown in the figure are as follows. It is shown by the equations (1) and (2). F = (X ² + Y ² ) ^1/2 ··· (1) θ = tan ⁻¹ (Y / X) ··· (2)

Although not shown, in the case of a three-component sensor for geomagnetism, the plane including the xy coordinate axes in FIG. 4 is a horizontal plane, and the z axis is vertically downward with respect to the xy coordinate axes. To take. Similarly to the case of the two-component sensor, if the output value of the magnetic detection unit 3x is X, the output value of the magnetic detection unit 3y is Y, and the output value of the magnetic detection unit 3z is Z, the angle of deviation from the x-axis is calculated. The (declination angle) θ is represented by the above equation (2), and the total magnetic force F and the inclination (angle of dip) χ of the magnetic field vector from the horizontal plane are represented by the following equations (3) and (4), respectively. F = (X ² + Y ² + Z ² ) ^1/2 ... (3) χ = tan ^-1 [Z / (X ² + Y ² ) ^1/2 ] ... (4)

Equations (1) and (2) are calculated for the two-component sensor, and equations (2), (3) and (4) are calculated for the three-component sensor for geomagnetism. Then, the magnetic field strength F and the deviation angle θ from the x-axis, the total magnetic force F and the deviation angle θ from the x-axis, and the dip angle χ of the magnetic field vector from the horizontal plane are calculated. If you are targeting geomagnetism,
The x-axis is oriented northward, the y-axis is oriented eastward, and the z-axis is oriented vertically downward. The declination θ is measured from north to east, and eastward is positive and westward is negative. The dip angle χ is positive in the downward direction and negative in the upward direction from the horizontal plane.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Two sets of magnetic detection units 3 of the magnetic sensor of the present invention shown in FIG. 1 are arranged so as to be orthogonal to each other to manufacture a magnetic azimuth sensor having a magnetic azimuth detection unit 10 shown in FIG. did. 5A is a plan view of the magnetic azimuth detecting unit 10 of the magnetic azimuth sensor in the embodiment according to the present invention, FIG. 5B is a sectional view taken along line BB of FIG. 5A, and 10a is a substrate. Is shown. The size of the magnetic azimuth detecting unit 10 is 10 mm × 10
mm × 4 mm. Further, the magnetic / magnetic azimuth was measured by the magnetic / magnetic azimuth measuring method of the present invention using these magnetic sensors and magnetic azimuth sensors. The composition of the amorphous magnetic wire 1 is (Fe ₆ Co ₉₄ ) _72.5 Si _12.5 B ₁₅ ,
Magnetostriction constant λ _s = −10 ⁻⁷ , diameter 50 μ, effective length 5 mm
I used the one. The coil for applying the bias magnetic field had 300 turns and a coil diameter of 3 mm, and this coil generated a bias magnetic field of ± 500 A / m. Resistance 4
Had a resistance value of 100Ω, and the frequency f of the high-frequency current passed through each amorphous magnetic wire 1 was 300 kHz.

The measurement results of the magnetic and magnetic directions in this example are shown in FIGS. 6 and 7. That is, x
With an azimuth angle φ being an angle measured from the positive axis direction around the positive y axis direction, the X output (V) of the magnetic detection unit 3x and the Y output of the magnetic detection unit 3y when the azimuth angle φ is in the range of 0 ° to 360 ° ( As a result of measuring V), two sinusoidal curves having a phase difference of 90 ° with respect to the azimuth angle φ were obtained as shown in FIG. Figure 6
Is the X output (V) of the magnetic detector 3x and Y of the magnetic detector 3y.
The azimuth angle dependence of output (V) is shown. Further, the values of the X output and the Y output at each azimuth angle φ were calculated by a microcomputer, and the values of tan θ and the azimuth output were obtained from the ratios thereof. The azimuth output is a numerical value in an arbitrary unit that represents the output value in the circuit obtained in a one-to-one correspondence with the azimuth angle φ. The resulting FIG. 7 shows the azimuth angle dependence of the azimuth output. The graph of FIG. 7 has good linearity, and it can be seen that the magnetic azimuth can be measured with an azimuth accuracy of ± 1 °.

The size of the magnetic direction detecting portion 10 of the magnetic direction sensor used in this embodiment was 10 mm × 10 mm × 4 mm, which is a size that can be incorporated in an electronic circuit board. On the other hand, a conventional flux gate type magnetic bearing sensor (FG370 type, bearing accuracy ± 1 °) that is commercially available
The size of the magnetic azimuth detector is 25mm × 25mm × 10
The size is mm, and the volume reaches about 8 times that of the magnetic azimuth detecting unit of the magnetic azimuth sensor used in this embodiment. Figure 8
FIG. 4 is a comparison diagram of the sizes of both magnetic azimuth detecting units. Furthermore,
The magnetic azimuth detecting portion of the magnetic azimuth sensor in the present invention can theoretically be reduced to about 5 mm × 5 mm × 2 mm, and the volume ratio reaches 1: 125.

[0022]

As described above, the magnetic / magnetic direction sensor of the present invention has sufficient accuracy to detect the earth's magnetism, and the magnetic direction detector of the conventional fluxgate type magnetic direction sensor. Compared with the above, the volume is about ⅛ or less, and it is small and easy to be incorporated in the device.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration example of a magnetic sensor according to the present invention.

FIG. 2 is a diagram showing a structural example of a basic circuit for measuring a voltage across a wire when an external magnetic field is applied in the longitudinal direction of the a-wire and a high-frequency current is applied to both ends thereof.

3 is a graph of the external magnetic field versus the voltage across the wire measured using the measurement circuit of FIG.

FIG. 4 is a configuration diagram of a magnetic azimuth detecting unit of the magnetic azimuth sensor according to the present invention.

FIG. 5A is a plan view of a magnetic azimuth detecting unit of the magnetic azimuth sensor according to the embodiment of the present invention. (B) is sectional drawing of the magnetic direction detection part of the magnetic direction sensor of the Example of this invention.

FIG. 6 is a graph showing the azimuth angle dependence of the X and Y outputs of the magnetic detector obtained in the example of the magnetic sensor according to the present invention.

FIG. 7 is a graph showing the azimuth angle dependence of the azimuth output obtained in the example of the magnetic sensor according to the present invention.

FIG. 8 is a dimensional comparison diagram of the magnetic azimuth detecting unit in the magnetic azimuth sensor of the present invention and the magnetic azimuth detecting unit of the conventional fluxgate type magnetic azimuth sensor.

[Explanation of symbols]

 1 Amorphous magnetic wire 2 Coil for applying bias magnetic field 3 Magnetic detection part of magnetic sensor 3x Magnetic component x detection of magnetic sensor 3y Magnetic component y detection of magnetic sensor 4 Resistor 5 High frequency power supply 6 Amplifier 7 Detector 8 Low pass filter 9 differential amplifier 10 magnetic azimuth detecting unit of magnetic azimuth sensor 10a substrate of magnetic azimuth detecting unit of magnetic azimuth sensor

Claims (6)

[Claims] 1. A magnetic detection unit is configured by including an amorphous magnetic wire and a coil or a permanent magnet that applies a bias magnetic field to the amorphous magnetic wire, and a pair of the magnetic detection units are arranged in parallel to each other. Magnetic sensor. 2. A magnetic azimuth sensor comprising a magnetic azimuth detecting unit configured by arranging two sets or three sets of the magnetic sensor according to claim 1 so as to be orthogonal to each other. 3. A magnetic detection unit is constituted by an amorphous magnetic wire and a coil or a permanent magnet for applying a bias magnetic field to the amorphous magnetic wire, and a pair of the magnetic detection units are arranged in parallel to each other. A high-frequency current is applied to each of the amorphous magnetic wires of the magnetic sensor to generate a bias magnetic field having the same strength and opposite direction in the pair of coils or permanent magnets, and the voltage across the amorphous magnetic wires is Detect the difference,
A magnetic measurement method for measuring the strength and direction of a magnetic field in the longitudinal direction of the magnetic detection unit. 4. The amorphous magnetic wire of each set of the magnetic azimuth detecting unit comprising the magnetic sensor according to claim 3, wherein two or three sets of the magnetic sensors are arranged so as to be orthogonal to each other. A high-frequency current is applied to the pair of coils or permanent magnets to generate a bias magnetic field of equal strength and opposite directions, and the difference between the voltages across the amorphous magnetic wires of each set is detected to detect each set. The magnetic azimuth measuring method of measuring the strength and direction of the magnetic field in the longitudinal direction of the magnetic detection part, and synthesizing these to measure the strength and direction of the magnetic field. 5. The frequency of the high frequency current is 10 kHz to 30.
The magnetic measurement method according to claim 3, which has a frequency of MHz. 6. The frequency of the high frequency current is 10 kHz to 30.
The magnetic azimuth measuring method according to claim 4, wherein the magnetic azimuth is MHz.