JPH1164474A - Magnetic sensor and magnetic orientation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor and a magnetic orientation sensor in which the operational stability and the temperature stability are improved while reducing the circuitry and the number of adjusting parts thereof. SOLUTION: The magnetic sensor comprises a magnetic measuring section 3 including an amorphous magnetic wire 1 to be supplied with a high frequency current and a coil 2 producing a bias field, and means for detecting a current level for generating a field of the same magnitude as an outer measuring field in the opposite direction by varying the level of DC current being supplied to the coil 2, wherein the strength and orientation of the longitudinal field at a magnetic measuring part are measured, based on a detected DC current value. The magnetic orientation sensor comprises a magnetic orientation measuring section where two or three sets of magnetic sensors are arranged orthogonally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor and a magnetic azimuth sensor for detecting a weak magnetic field such as terrestrial magnetism and measuring the intensity, direction and direction of the weak magnetic field. The present invention relates to an improvement in a magnetic sensor and a magnetic azimuth sensor capable of reducing the number of circuits and adjustment portions thereof and improving operation stability and temperature stability.

In the following description, the strength of a magnetic field means the total magnetic force in the case of geomagnetism, and the direction means a one-dimensional direction.

[0003]

2. Description of the Related Art Conventionally, for example, geomagnetism (tens of thousands of nT,
/ M) is most frequently used as a magnetic azimuth sensor for accurately detecting (/ m). The flux gate type magnetic sensor measures the magnetic field by utilizing the fact that the symmetrical BH saturation characteristic of a high magnetic permeability core such as permalloy is changed by an external magnetic field, and has an azimuth measurement accuracy of ± 1 °. . However, a fluxgate magnetic sensor for detecting terrestrial magnetism requires a large magnetic core for a theoretical reason, and it is impossible to reduce the size and shape of the entire sensor. Magnetic sensors other than the flux gate type magnetic sensor include a Hall element using a semiconductor and a magnetoresistive element using a thin film of a magnetic material (hereinafter, a ferromagnetic material is simply referred to as a magnetic material). However, although these are small in size and shape, they have a drawback that the sensitivity to a magnetic field is insufficient for detecting the terrestrial magnetism by an order of magnitude, and the terrestrial magnetism cannot be detected accurately.

Under such technical background, the present inventors have
A magnetic sensor and a magnetic azimuth sensor which are small and have sufficient accuracy for detecting terrestrial magnetism have already been proposed (see Japanese Patent Application Laid-Open No. 7-248365).

That is, as shown in FIG. 10, this magnetic sensor comprises an amorphous magnetic wire a through which a high-frequency current flows, and a coil b for applying a bias magnetic field to the amorphous magnetic wire a. And a pair of magnetic measurement units c are arranged in parallel with each other.

In FIG. 10, d is a high-frequency power supply for supplying a high-frequency current to the amorphous magnetic wire a.
e denotes a resistor, f denotes an amplifier, g denotes a detector, h denotes a low-pass filter, and i denotes a differential amplifier.

In this magnetic sensor, when a high-frequency current is applied by a high-frequency power source d in the longitudinal direction of the amorphous magnetic wire a, a voltage is generated across the amorphous magnetic wire a and a voltage is generated around the amorphous magnetic wire a. A circumferential magnetic field H ₀ is generated (see FIG. 11). At this time, since the amorphous magnetic material wire a is a magnetic material, it has a self-inductance L showing self-inductivity for preventing a current change. Here, when an external magnetic field _Hex is applied in the longitudinal direction of the amorphous magnetic wire a, the magnetization vector of the amorphous magnetic wire a by an angle ψ (0 ° <ψ <90 °) corresponding to the strength of the external magnetic field _Hex. M inclines (see FIG. 11). As a result, the effective magnetic component in the circumferential direction acting as the inductance is M · cosψ (0 <
cosψ <1), and the self-inductance L decreases. From this change in self inductance L,
The strength of the external magnetic field _Hex applied in the longitudinal direction of the amorphous magnetic wire a can be detected. On the contrary, the change of the self-inductance L is caused by the voltage across the wire when a high-frequency current is applied in the longitudinal direction of the amorphous magnetic wire a. Is determined from the change in

FIG. 12 shows both ends of an amorphous magnetic wire a when an external magnetic field _Hex (A / m) is applied in the longitudinal direction of the amorphous magnetic wire a and a high-frequency current from a high-frequency power source d is applied to both ends of the amorphous magnetic wire a. 2 shows a basic circuit for measuring a voltage (mVp-p). The composition is (F
e ₆ Co ₉₄ ) A resistor e having a resistance value of 100Ω is arranged in series with an amorphous magnetic wire a of _72.5 Si _12.5 B ₁₅ , and an external magnetic field H when the frequency of the high-frequency current is 300 kHz.
The change of the voltage (mVp-p) across the wire with respect to _ex (A / m) is shown in the graph of FIG.

FIG. 13 is a graph _showing an external magnetic field H _ex ± 20.
In the vicinity of 0 (A / m), the voltage between both ends of the wire becomes the maximum value, and is symmetrical with respect to the external magnetic field H _ex 0.
The state of the curves in the graph differs depending on the material and shape of the amorphous magnetic wire a, the frequency of the high-frequency current to be applied, and the like. In each case, the ordinate axis at a magnetic field of 0 (A / m) is taken as the symmetry axis, and Peak shape or mountain shape of FIG. 14 (unlike the case of FIG. 13, the frequency of the high-frequency current applied to the amorphous magnetic wire is 70 kHz)
It becomes a symmetrical curve like In the state of the curve in the graph of FIG. 13, the direction of the external magnetic field H _ex is not known from the voltage across the wire, and when the voltage across the wire is 55 mVp-p or more, the strength of the external magnetic field H _ex becomes multivalent. Undecided,
The external magnetic field _Hex cannot be detected. FIG.
Even in the curved state of the graph, the direction of the external magnetic field _Hex cannot be detected from the voltage across the wire.

Therefore, the magnetic sensor developed by the present inventors has a magnetic measuring section c comprising an amorphous magnetic wire a and a coil b for applying a bias magnetic field to the amorphous magnetic wire a as shown in FIG. And the two magnetic measurement units c are arranged in parallel to form a pair.

Then, a high-frequency current is applied to each of the amorphous magnetic wires a, and a bias magnetic field having the same strength and the opposite direction is generated in the paired coils b. The strength and direction of the external magnetic field _{Hex in} the longitudinal direction of the magnetometer c are determined by detecting the difference between the voltages at both ends.

That is, in FIG. 13, for example, when the bias magnetic fields are -500 A / m and +500 A / m, respectively, +200 A / m to +500 A / m and -200 A / m.
A curve in the range of A / m to -500 A / m is available.
/ M, the intensity and direction of the external magnetic field _Hex can be measured.

FIG. 15 is a block diagram of the magnetic azimuth measuring unit of the magnetic azimuth sensor in the case of a two-component sensor, and the xy coordinate axes are also described for explanation of the operation. The magnetic azimuth measuring unit of this magnetic azimuth sensor is configured by arranging two sets (in the case of a two-component sensor) or three sets (in the case of a three-component sensor) of the magnetic measuring units in the magnetic sensor described above so as to be orthogonal to each other. I have. In the case of FIG. 15, the magnetic azimuth measuring unit of the magnetic azimuth sensor is configured by arranging the magnetic measuring unit cx and the magnetic measuring unit cy of the magnetic sensor so as to be orthogonal to each other. If the output value of the magnetism measuring unit cx is X and the output value of the magnetism measuring unit cy is Y, the magnetic field strength F and the angle of deviation (deviation) θ from the illustrated x-axis are as follows: Equation (1),
It is shown by equation (2).

F = (X ² + Y ² ) ^1/2 (1) θ = tan ⁻¹ (Y / X) (2) In the case of a three-component sensor for terrestrial magnetism, FIG.
The z-axis is taken vertically downward with respect to the xy coordinate axis of No. 5. Similarly to the case of the two-component sensor, the output value of the magnetic measurement unit cx is X, the output value of the magnetic measurement unit cy is Y, and the magnetic measurement unit cz
Is the output value of Z, the angle of deviation from the x-axis (declination angle) θ
Is expressed by the above equation (2), and the total magnetic force F and the inclination (declination) of the magnetic field vector from the horizontal plane are expressed 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) And measurement by the two-component sensor Then, the equations (1) and (2) are calculated. In the measurement by the three-component sensor for the terrestrial magnetism, the equations (2), (3) and (4) are calculated. Declination θ from x axis, total magnetic force F and x
Declination θ from the axis and the dip 磁場 of the magnetic field vector from the horizontal plane
Is calculated.

In the case of geomagnetism, x is directed northward.
The axis, the y-axis to the east, and the z-axis to the vertical downward, the declination θ is measured from north to east, with the eastward being positive and the westward being negative. The inclination χ takes a positive value downward from the horizontal plane and a negative value upward.

[0017]

By the way, the sensor circuit such as the magnetic sensor developed by the inventors of the present invention has two amorphous magnetic wires a in parallel as shown in FIG. The arrangement is such that a bias magnetic field in the opposite direction is constantly applied to each of the amorphous magnetic wires a to detect a voltage difference generated between the amorphous magnetic wires a.

Therefore, since two magnetic measuring units c each of which is mainly composed of the amorphous magnetic wire a and the coil b are required, the sensor circuit becomes complicated, which is disadvantageous in terms of cost, and the difference is large. In order to obtain an output from the dynamic output, if the magnetic sensitivities of the respective magnetic measurement units c do not match, the output becomes an error, and thus there is a problem that an adjustment for avoiding the error is required.

Further, when the characteristics of the respective magnetic measurement units c with respect to the temperature do not match, there is a problem that a large temperature drift occurs.

The present invention has been made in view of such a problem, and an object thereof is to reduce the number of circuits in a magnetic sensor and the like and the adjustment portions thereof, and also to provide stable operation and temperature stability. It is an object of the present invention to provide a magnetic sensor and a magnetic azimuth sensor capable of improving the magnetic field.

[0021]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have devised a measurement principle capable of performing magnetic measurement with a single magnetic measurement unit. That is, while monitoring the impedance of the amorphous magnetic material wire, a direct current is applied to a coil arranged around the wire to generate a magnetic field. When a magnetic field having the same magnitude in the opposite direction to the external magnetic field is applied by the coil so that the magnetic field generated from this coil cancels the external measurement magnetic field, the relationship between the magnetic field and the voltage across the wire depends on the material,
By setting the shape, frequency, etc., the impedance of the amorphous magnetic wire exhibiting the characteristics of the bimodal curve of FIG. 13 is minimized, and the relationship between the magnetic field and the voltage between both ends of the wire is the characteristic of the mountain curve of FIG. In the illustrated amorphous magnetic wire, the impedance is maximized. Since the magnetic field generated from the coil at this time is uniquely determined from the DC current, the direction and magnitude of the externally measured magnetic field can be known by measuring the DC current flowing through the coil.

That is, the value of the direct current flowing through the coil is changed, and the external magnetic field can be detected from the coil current at which the impedance of the amorphous magnetic wire becomes minimum or maximum. In this case, since the magnitude of the magnetic field including the direction can be determined from one magnetic measurement unit, there is no need to dispose two magnetic measurement units as in the case of obtaining a differential output. In addition, when the peripheral magnetic field of the amorphous magnetic wire is zero, only the characteristic that the impedance is minimized or maximized is used. Therefore, even if the amount of change in the impedance with respect to the magnetic field changes, the detection result is not affected. It also has the advantage of not giving. For example, even if the characteristics of the amorphous magnetic wire change with temperature and the amount of change in impedance with respect to the magnetic field changes, the characteristics of the amorphous magnetic wire whose impedance becomes minimal or maximal at zero magnetic field do not change. Alternatively, the external magnetic field can be accurately detected by measuring the value of the DC current flowing through the coil at the maximum value. The present invention has been completed through such technical studies.

That is, the invention according to claim 1 includes a single amorphous magnetic wire through which a high-frequency current is supplied;
Assuming a magnetic sensor having a magnetic measuring unit whose main part is composed of a coil that applies a bias magnetic field to this amorphous magnetic wire, and changing the value of the DC current flowing through the coil to be the same as the external measuring magnetic field Providing detection means for detecting a DC current value that generates a magnetic field in a direction opposite to the magnitude,
The strength and direction of the magnetic field in the longitudinal direction of the magnetic measuring unit are measured from the detected DC current value.

The relationship between the magnetic field and the voltage between both ends of the wire shows the characteristics of the amorphous magnetic wire having the bimodal curve shown in FIG. 13 and the characteristics of the mountain curve shown in FIG. 14 by setting the material, shape, frequency and the like. In comparison with an amorphous magnetic wire, when the present invention is applied, in the amorphous magnetic wire showing the characteristics of the bimodal curve of FIG. 13, the measurement region is in a range of approximately −400 A / m to approximately +400 A / m. Because of the limitation (because there is a magnetic field having an impedance lower than the impedance of the zero magnetic field outside this range, the external magnetic field cannot be measured from the minimum value of the impedance), the chevron curve of FIG. It is more advantageous to use an amorphous magnetic wire having the following characteristics. The invention according to claim 2 relates to an invention in which the configuration of the detection means is specified when an amorphous magnetic wire showing the characteristics of the chevron curve in FIG. 14 is applied by setting its material, shape, frequency, and the like.

That is, a second aspect of the present invention is based on the magnetic sensor according to the first aspect of the present invention, wherein the detecting means includes a saw-tooth wave oscillator for supplying a saw-tooth current to a coil;
A peak detection circuit that detects a peak from a high-frequency impedance waveform signal monitored from a voltage between both ends of the amorphous magnetic wire, a one-shot oscillator that oscillates a pulse in synchronization with a peak signal from the peak detection circuit, and a one-shot oscillator. The main part is constituted by a sample and hold circuit which samples a sawtooth wave current from the sawtooth wave oscillator in synchronization with a pulse signal from the oscillator and holds the current.

Further, the invention according to claim 3 relates to a magnetic direction sensor constituted by combining a plurality of magnetic sensors according to claim 1 or 2.

That is, the invention according to claim 3 is based on a magnetic direction sensor for measuring the strength and direction of a magnetic field, and two or three sets of magnetic sensors according to claim 1 or 2 are arranged so as to be orthogonal to each other. A magnetic azimuth measuring unit configured as described above, and measures the strength and direction of the magnetic field in the longitudinal direction of the magnetic measuring unit in each magnetic sensor and combines them to measure the strength and azimuth of the magnetic field. It is characterized by the following.

The amorphous magnetic wire used in the present invention is made of a CoSiB-based wire, similar to the wire for a magnetic sensor and the like described in JP-A-7-248365.
After melting FeCoSiB-based alloys and other alloys,
The liquid is super-cooled and the cross section is circular. Further, it is subjected to tension annealing to adjust the magnetostriction constant λ _s and the magnetic anisotropy, and has strong magnetic anisotropy in the circumferential direction of the amorphous magnetic wire. As for the magnetostriction constant lambda _s, if the absolute value of the magnetostriction constant lambda _s is less than 10 ^-6,
Since the voltage between both ends of the wire, which will be described later, becomes small and detection becomes difficult, it is desirable to use a wire having a range of −10 ⁻⁶ <λ _s ≦ 0. Also, the diameter of the amorphous magnetic wire is
The range of 30 μm to 150 μm is preferable because the detection sensitivity is large, and the length can be used from about 1 mm or more.
3 mm or more is desirable from the viewpoint of easy output.

Further, the material of the amorphous magnetic wire,
Although depending on the structure of the magnetic sensor, the frequency f of the high-frequency current applied to the amorphous magnetic wire in order to efficiently extract a change in impedance is 50 kHz to 10 MHz.
The range of z is desirable (claims 4 and 5). This is because the sensitivity to the magnetic field is significantly reduced outside this range.

As described above, according to the magnetic sensor and the magnetic azimuth sensor according to the present invention, two basic magnetic sensors are used.
The number of amorphous magnetic wires can be reduced to one as compared with the conventional magnetic sensor that required one amorphous magnetic wire, and the magnetic measurement unit can be made up of a single amorphous magnetic wire and a single coil. Since the number of components can be reduced, the number of components can be reduced and the size of the sensor can be reduced. In addition, since there is only one analog signal processing system corresponding to two circuits, balance adjustment is not required. Can be reduced.

Although the characteristics and circuit characteristics of the amorphous magnetic wire vary with temperature, as described above, the number of the amorphous magnetic wires of the basic magnetic sensor becomes one, and the characteristics of the amorphous magnetic wire are reduced. Even if the temperature changes with temperature, the characteristic that the impedance becomes minimal or maximal at zero magnetic field does not change, so that the operation stability and the temperature stability can be improved without employing a complicated circuit configuration.

[0032]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit conceptual diagram of a magnetic sensor according to the present invention. This magnetic sensor has a single amorphous magnetic field to which a high-frequency current (sine wave) is supplied from a high-frequency power supply (sine-wave oscillator) 4. Body wire 1 and sawtooth wave oscillator 10
And a single coil 2 to which a saw-tooth wave current is supplied from, and a magnetic measuring unit 3 whose main part is formed, and generates a magnetic field having the same magnitude as the external measuring magnetic field and having the opposite direction. Detection means for detecting the DC current value of the coil 2 is provided.

That is, the detecting means is provided by the coil 2
A saw-tooth wave oscillator 10 for applying a saw-tooth wave current to the same and a peak from a high-frequency impedance waveform signal α monitored from a voltage between both ends of the amorphous magnetic wire 1 via a detector 8 and a low-pass filter (LPF) 9. , A one-shot oscillator 13 that oscillates a pulse in synchronization with the peak signal from the peak detection circuit 12, and the sawtooth wave oscillator in synchronization with the pulse signal from the one-shot oscillator 13. The main part is constituted by a sample-and-hold circuit (S / H circuit) 14 which samples the saw-tooth wave current from 10 and holds the current.

In this magnetic sensor, a high-frequency current (sine wave) is supplied to the amorphous magnetic wire 1 from a high-frequency power supply (sine-wave oscillator) 4 and the coil 2 is supplied to the coil 2 from the sawtooth-wave oscillator 10 as shown in FIG. (A) corresponds to a change in the value of the sawtooth current when the sawtooth current (a direct current whose current value increases linearly and is set to an initial value repeatedly every unit time) is applied. As a result, the value of the high-frequency impedance monitored from the voltage between both ends of the amorphous magnetic wire 1 also changes, and a waveform signal α of the high-frequency impedance as shown in FIG. Input to the detection circuit 12.

Next, when the peak detection circuit 12 detects the peak value from the high-frequency impedance waveform signal α, the one-shot oscillator 13 oscillates a pulse in synchronization with the peak value, and the sample &amp; A hold circuit (S / H circuit) 14 samples the sawtooth wave current from the sawtooth wave oscillator 10 and holds the current to output a sensor output (DC output) as shown in FIG. 2C.

This DC output is a current value supplied to the coil 2 from the sawtooth oscillator 10 when the waveform signal α of the high-frequency impedance monitored from the voltage between both ends of the amorphous magnetic wire 1 is peaked. In other words, this current value is nothing but a DC current value at the time when a magnetic field of the same magnitude as the measurement magnetic field outside the sensor and in the opposite direction is generated from the coil 2. Therefore, the direction and magnitude of the externally measured magnetic field can be obtained from the DC output.

The greatest advantage of this magnetic sensor as compared with the conventional magnetic sensor is that the magnetic measurement unit can be constituted by a single amorphous magnetic wire and a single coil, Even if the characteristic of the magnetic wire changes with temperature, the characteristic that the impedance becomes maximum at zero magnetic field does not change, so that operation stability and temperature stability can be improved without employing a complicated circuit configuration.

In this magnetic sensor, the waveform signal α of the high-frequency impedance has a peak (that is, a maximum value).
Due to the adoption of the method of detecting the point of time and measuring the external magnetic field, an amorphous magnetic wire having a mountain-shaped curve shown in FIG. 3 is applied. Specifically, the composition is (Fe ₆ Co ₉₄ ) _72.5 Si _12.5 B ₁₅ and the magnetostriction constant λ _s = −
An amorphous magnetic wire of 10 ^-7 , 50 μm in diameter and 5 mm in effective length is applied. A coil 2 having the same number of turns and a coil diameter of 3 mm was applied to the coil 2 for generating a magnetic field having the same magnitude as the measurement magnetic field and in the opposite direction.

The above-mentioned amorphous magnetic wire 1 is connected to a high frequency power supply (sine wave oscillator) 4 at 70 kHz, 8 kHz.
A high-frequency current (sine wave) of mA is applied, and the coil 2
A sawtooth wave current of 100 Hz, ± 50 mA is supplied from the sawtooth oscillator 10.

FIG. 4 shows a specific circuit configuration example of the magnetic sensor.

That is, this magnetic sensor has a magnetic measuring section mainly composed of a single amorphous magnetic wire 1 to which a high-frequency current is supplied and a single coil 2 to which a sawtooth current is supplied. 3 and a detecting means for detecting a DC current value of the coil 2 for generating a magnetic field having the same magnitude as the measurement magnetic field and having an opposite direction.

That is, the detecting means is provided by the coil 2
And a peak detector for detecting a peak from a high-frequency impedance waveform signal monitored via a detector 8 and a low-pass filter 9 from a voltage between both ends of the amorphous magnetic wire 1. Circuit 12
And a one-shot oscillator 13 that oscillates a pulse in synchronization with the peak signal from the peak detection circuit 12, and a saw-tooth wave current from the saw-tooth wave oscillator 10 in synchronization with the pulse signal from the one-shot oscillator 13. The main part is constituted by a sample & hold circuit (S / H circuit) 14 for sampling and holding the current. FIG.
Among them, 4 is a high frequency power supply, 5, 7, 11, and 15 are amplifiers, 6
Is resistance.

[0044]

Embodiments of the present invention will be described below with reference to the drawings.

A magnetic azimuth sensor having a magnetic azimuth measuring unit 100 as shown in FIG. 5 is manufactured by arranging two sets of the magnetic measuring units 3 of the magnetic sensor of the present invention shown in FIG. did. In FIG. 5, reference numerals 1 and 2 denote an amorphous magnetic material wire and a coil constituting one magnetic measurement unit 3, and 1 ′ and 2 ′ denote an amorphous magnetic material wire constituting the other magnetic measurement unit 3 ′. Show the coils respectively,
Reference numeral 101 denotes a substrate, and 102 denotes an electrode constituting a part of one of the magnetic measurement units.

Further, as the number of the magnetic measurement units is increased to two, a circuit configuration of an additional magnetic sensor is added as shown in FIG. In FIG. 6, 6 'is a resistor, 7' is an amplifier, 8 'is a detector, 9' is a low-pass filter, 12 'is a peak detection circuit, 13' is a one-shot oscillator, and 14 'is a sample and hold circuit. (S / H circuit) are shown. Also, the components denoted by the same reference numerals as those in FIG. 4 indicate the same components as those in FIG.

In this magnetic azimuth sensor, the amorphous magnetic wires 1, 1 'have a composition of (Fe ₆ C).
o ₉₄₎ in _72.5 Si _12.5 B _15, the magnetostriction constant λ _s = -10 ^-7,
Each having a diameter of 50 μm and an effective length of 5 mm is applied. The coils 2 and 2 ′ have a number of turns of 30.
0, coil diameter 3 mm. The resistances of the resistors 6 and 6 ′ are 100Ω, and each of the amorphous magnetic wires 1 and 1 ′.
The high-frequency current to be applied to the coils is 70 kHz and 8 mA, and the sawtooth current to be applied to each of the coils 2 and 2 ′ is 100 Hz and ± 50 m.
A.

Then, the magnetic azimuth was measured using this magnetic azimuth sensor. The results are shown in FIGS. That is, an angle measured from the positive x-axis direction to the positive y-axis direction is defined as the azimuth angle φ, and the X output (V) of the magnetic measurement unit 3 and the magnetic measurement unit 3 ′ when the azimuth angle φ is in the range of 0 ° to 360 °. As a result of measuring the Y output (V), two sine curves having a phase difference of 90 ° with respect to the azimuth angle φ as shown in FIG. 7 were obtained. FIG.
Indicates the azimuth angle dependency of the X output (V) of the magnetic measurement unit 3 and the Y output (V) of the magnetic measurement unit 3 '.

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 determined from these ratios. The azimuth output is a numerical value in an arbitrary unit representing an output value in the circuit obtained in one-to-one correspondence with the azimuth angle φ.

FIG. 8 shows the azimuth dependence of the azimuth output. The graph of FIG. 8 has good linearity, and it can be seen that the magnetic azimuth can be measured with an azimuth accuracy of ± 1 °, similarly to the magnetic azimuth sensor described in JP-A-7-248365.

Next, FIG. 9 is a graph showing the relationship between the temperature and the output in the magnetic azimuth sensor according to the embodiment and the magnetic azimuth sensor (comparative example) described in JP-A-7-248365. . That is, it shows the temperature dependence of the sensor output of each sensor normalized by the value of 20 ° C.

From this graph, it is confirmed that the temperature stability of the magnetic azimuth sensor according to the embodiment is remarkably improved.

[0053]

According to the magnetic sensor and the magnetic azimuth sensor according to the first to fifth aspects of the present invention, the basic magnetic sensor is more amorphous than the conventional magnetic sensor which requires two amorphous magnetic wires. Since the number of magnetic wires can be reduced to one, and the magnetic measurement unit can be configured with a single amorphous magnetic wire and a single coil, the number of parts can be reduced and the sensor can be downsized. In addition, since there is only one analog signal processing system corresponding to two circuits, balance adjustment is not required, and accordingly, there is an effect that the number of adjustment parts in the circuit configuration can be reduced.

Although the characteristics and circuit characteristics of the amorphous magnetic wire vary with the temperature, the number of amorphous magnetic wires of the basic magnetic sensor is reduced to one.
Moreover, even if the characteristics of the amorphous magnetic material wire change with temperature, the characteristic that the impedance becomes minimal or maximal at zero magnetic field does not change, so that the operation stability and temperature stability can be improved without employing a complicated circuit configuration. It has an effect that can be achieved.

[Brief description of the drawings]

FIG. 1 is a circuit conceptual diagram of a magnetic sensor according to the present invention.

FIG. 2 is a timing chart showing a flow of signal processing in the magnetic sensor.

FIG. 3 is a graph showing a relationship between a bias magnetic field of a magnetic sensor and a voltage between both ends of an amorphous magnetic wire.

FIG. 4 is a block diagram showing a circuit configuration example of a magnetic sensor according to the present invention.

FIG. 5 is a schematic perspective view of a magnetic azimuth measuring unit of the magnetic azimuth sensor according to the embodiment.

FIG. 6 is a block diagram showing a circuit configuration example of a magnetic direction sensor according to the embodiment.

FIG. 7 is a graph showing the azimuth dependence of the X and Y outputs of the magnetic measurement unit obtained in the embodiment of the magnetic azimuth sensor according to the embodiment.

FIG. 8 is a graph showing the azimuth angle dependence of the azimuth output obtained by the magnetic azimuth sensor according to the embodiment.

FIG. 9 is a graph showing the relationship between the temperature and the sensor output of the magnetic azimuth sensors according to the example and the comparative example.

FIG. 10 is a block diagram showing a circuit configuration example of a magnetic sensor according to a conventional example.

FIG. 11 is an explanatory diagram for explaining characteristics when a high-frequency current is applied to an amorphous magnetic wire.

FIG. 12 is a block diagram showing a configuration 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 amorphous magnetic wire and a high-frequency current is applied to both ends in the magnetic sensor according to the conventional example. .

FIG. 13 is a graph showing a relationship between an external magnetic field measured using the measurement circuit of FIG. 12 and a voltage between both ends of an amorphous magnetic wire.

FIG. 14 shows a case where the frequency of a high-frequency current applied to the amorphous magnetic wire using the measurement circuit of FIG. 12 is 70 kHz.
FIG. 7 is a graph showing the relationship between the measured external magnetic field and the voltage across the amorphous magnetic wire in the case of FIG.

FIG. 15 is a block diagram showing a circuit configuration example of a magnetic direction sensor according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Amorphous magnetic wire 2 Coil 3 Magnetic measurement part 4 High frequency power supply (sinusoidal oscillator) 8 Detector 9 Low-pass filter (LPF) 10 Sawtooth oscillator 12 Peak detection circuit 13 One-shot oscillator 14 Sample & hold circuit (S / H circuit)

Claims (5)

[Claims] 1. A magnetic sensor having a magnetic measuring unit whose main part is constituted by a single amorphous magnetic wire through which a high-frequency current is supplied and a coil for applying a bias magnetic field to the amorphous magnetic wire, Detecting means is provided for detecting a DC current value that changes the value of the DC current flowing through the coil to generate a magnetic field having the same magnitude as the externally measured magnetic field and in the opposite direction, and detects the length of the magnetic measurement unit from the detected DC current value. A magnetic sensor characterized by measuring the strength and direction of a magnetic field in a direction. 2. A saw-tooth wave oscillator for applying a saw-tooth wave current to a coil, and a peak detection for detecting a peak from a high-frequency impedance waveform signal monitored from a voltage across the amorphous magnetic wire. Circuit and
A one-shot oscillator that oscillates a pulse in synchronization with a peak signal from a peak detection circuit, and samples and holds the sawtooth wave current from the sawtooth wave oscillator in synchronization with a pulse signal from the one-shot oscillator 2. The magnetic sensor according to claim 1, wherein the main part is constituted by a sample and hold circuit. 3. A magnetic azimuth measuring unit comprising two or three sets of the magnetic sensors according to claim 1 arranged so as to be orthogonal to each other, and a longitudinal direction of the magnetic measuring unit in each magnetic sensor. A magnetic azimuth sensor which measures the strength and direction of a magnetic field and combines them to measure the strength and azimuth of the magnetic field. 4. The magnetic sensor according to claim 1, wherein the frequency of the high-frequency current applied to the amorphous magnetic wire is 50 kHz to 10 MHz. 5. The magnetic azimuth sensor according to claim 3, wherein the frequency of the high-frequency current applied to the amorphous magnetic wire is 50 kHz to 10 MHz.