JPH09257896A - Magnetometer - Google Patents

Abstract

(57) Abstract: An object of the present invention is to obtain a magnetometer with a small error in measuring the absolute value of the magnetic field by preventing output fluctuations of the magnetometer due to phase fluctuations, amplitude fluctuations, etc. of electronic circuits. A reference signal generation circuit for generating a calibration magnetic field, a current source and a magnetic field generation coil, a bandpass filter and a comparison circuit for extracting a calibration signal for calibration from an output of a drive circuit and comparing it with a reference signal, and the above drive. By adding a filter that removes the calibration signal from the output of the circuit and a correction circuit that corrects the output fluctuation of the magnetometer based on the output of this filter and the output of the above comparison circuit, the fluctuation of the magnetometer output will not occur. In order to obtain a magnetometer with a small measurement error of the absolute value of the magnetic field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting quantum interference device (Superconducting Quantum).
(Interference Device: hereinafter referred to as SQUID for short) relating to improvement of a highly sensitive magnetometer.

[0002]

2. Description of the Related Art FIG. 13 is a block diagram of a conventional magnetometer disclosed in Japanese Patent Laid-Open No. 3-152488. In the figure, 1A, 1B, and 1C are SQUIDs fixed on the three planes of the sensor block 2 forming a predetermined angle with each other.
In addition, the case where the predetermined angle is about 90 degrees is shown as an example. 3A, 3B and 3C are SQUID 1A,
A driving circuit for driving 1B, 1C to obtain a desired output, 4 is an unknown number calculating circuit for calculating an unknown number using the outputs of the driving circuits 3A, 3B, 3C, 5 is an output of the unknown number calculating circuit 4 and the driving circuit It is a magnetic field calculation circuit that calculates the measured magnetic field using the outputs of 3A, 3B, and 3C. The drive circuits 3A, 3B, and 3C are FLL (Flux Locked).
A known circuit called a “Loop) circuit, and its operation is, for example, a Review Of Scientific.
Instrument, 1984, Volume 55, Volume 9
Pp. 52-957. Here, it is assumed that the oscillators that drive the SQUIDs 1A, 1B, and 1C are provided in the drive circuits 3A, 3B, and 3C, respectively.

Next, each signal shown in FIG. 13 will be described. Δu _m , Δv _m , and Δw _m are time t _m (m = 1,
2, ..., a drive circuit 3A in 9), 3B, 3C _{output, Δu n, Δv n, Δw} n the time t _m after the time t _n
Output of the drive circuits 3A, 3B, 3C, K ₁ ,
K _2, ..., K ₈ is the calculated value of the unknown quantities calculation circuit 4, F is the calculated value of the magnetic field calculation circuit 5.

Next, the operation of the conventional magnetometer will be described. In the following description, the case where a conventional magnetometer is mounted on a moving object such as an aircraft is taken as an example, and the geomagnetism is regarded as the magnetic field to be measured.

First, SQUIDs 1A, 1B, and 1C are cooled by immersing them in liquid helium or the like, and are transformed into superconductivity.
Next, drive circuits 3A, 3B, 3C to SQUIDs 1A, 1
A DC bias current is applied to each of B and 1C. Next, by the drive circuits 3A, 3B, 3C, SQUIDs 1A, 1B,
Magnetic flux locks 1C at the same time. After the magnetic flux lock, the magnetic flux lock value, that is, the initial magnetic flux is set as the origin of output zero, and a value proportional to the relative magnetic field change amount from that is output. Since the incident angle of the geomagnetic field changes with the turning of the aircraft, Δu
_m , Δv _m , and Δw _m change every moment.

Next, an xyz orthogonal coordinate system and a uvw oblique coordinate system as shown in FIG. 14 are defined, and the u axis and v axis, and the v axis and w axis.
The angles formed by the axis, the w axis and the u axis are 90 + α and 90, respectively.
+ Β and 90 + γ. In FIG. 14, the z-axis and the w-axis match, but generality is not lost.

FIG. 15 shows SQUIDs 1A, 1B, 1C and u.
It is a diagram showing the relationship with the vw oblique coordinate system. u axis,
The v-axis and the w-axis are perpendicular to SQUIDs 1A, 1B, and 1C, respectively, and coincide with the sensitivity axes of SQUIDs, respectively.

In the above coordinate system, the component display ξ _m , η _m , ζ _m and xy of the absolute value H of the earth's magnetism in the uvw oblique coordinate system.
The following relationships are established between the component representations x _m , y _m , and z _m in the z orthogonal coordinate system by using α, β, and γ.

[0009]

[Equation 1]

The initial magnetic fluxes of SQUIDs 1A, 1B, 1C are u ₀ , v ₀ , w ₀ , respectively, and SQUIDs 1A, 1
When the sensitivities of B and 1C are Gu, Gv, and Gw, respectively, and the values Δu _m , Δv _m , and Δw _m that are proportional to the amount of change in the magnetic field and the equations (1) to (3) are used, the geomagnetism H is represented by the following equation. .

[0011]

[Equation 2]

Substituting equation (5) into equation (4) and rearranging,
It can be expressed as the following equation using the coefficients k _{1 to} k ₁₀ .

[0013]

(Equation 3)

K _{1 to} k ₁₀ are α, β, γ, u ₀ , v ₀ , w
₀ , Gu, Gv, Gw. Here, the function F (Δu _m , Δv _m , Δw _m ) is determined as in Expression (7).

[0015]

(Equation 4)

However, K ₁ = k ₂ / k ₁ , K ₂ = k ₃ / k
₁ , K ₃ = k ₄ / k ₁ , K ₄ = k ₅ / k ₁ , K ₅ = k ₆
/ K ₁ , K ₆ = k ₇ / k ₁ , K ₇ = k ₈ / k ₁ , K ₈ =
If k ₉ / k ₁ H is constant, the value of F does not change even if the incident angle of geomagnetism changes. Therefore, at time t _{m + 1} , Δ
Equation (8) is established between u _{m + 1} , Δv _{m + 1} , and Δw _{m + 1} .

[0017]

(Equation 5)

From the equations (7) and (8), if H is constant, the equation (9) holds for any m.

[0019]

(Equation 6)

Therefore, while changing the attitude of the sensor block by turning or rotating by a rotating mechanism with the geomagnetism H kept constant by raising the flight altitude sufficiently, at times t ₁ , t ₂ , ... Drive circuit 3 at t ₉
The set of outputs of A, 3B, and 3C (Δu ₁ , Δv ₁ , Δ
w ₁ ), (Δu ₂ , Δv ₂ , Δw ₂ ), ..., (Δu ₉ ,
Δv ₉ , Δw ₉ ) is measured and sent to the unknown number calculation circuit 4.
Next, in the unknown number calculation circuit 4, these nine sets of numerical values are substituted into the equation (7) to solve the simultaneous linear equations, and K ₁ , K ₂ ,
The value of K ₈ is calculated and the calculated value is sent to the magnetic field calculation circuit 5.

Next, at the time t _n after the time t _m , the outputs Δu _n , Δv _n , and Δw _n of the drive circuits 3A, 3B, and 3C.
To the magnetic field calculation circuit 5. K _1, K ₂ to the magnetic field calculator 5 (7), ..., and calculates K ₈ and Δu _n, Δv _n, F by substituting the values of _{Δw n (Δu n, Δv n} , Δw n) a. This output is used, for example, to detect a change in the earth's magnetism from a change in the value of F and discover a magnetic substance.

[0022]

In the above-described magnetometer, the output of the magnetometer eventually fluctuates due to the output fluctuation of the electronic circuit forming the drive circuit, which causes a magnetic field measurement error. There was a point. Further, 9 sets of outputs of the drive circuit are obtained by the attitude change of the sensor block due to the turning of the airplane, the rotation of the rotating mechanism, etc. The airplane and the rotating mechanism have magnetism due to the airframe material, the motor, etc. At the time of change, there is a problem that the calculated coefficient is affected by the adverse effect of magnetism and an error occurs. In addition, when cooling the SQUID by immersing it in liquid helium, the above SQUID
Causes a phenomenon called "flux trap" that catches magnetic flux on itself because it is directly transferred to superconductivity while directly receiving the earth's magnetism, and as a result, the output voltage of SQUID decreases and measurement sensitivity deteriorates. In some extreme cases, it did not work as a magnetometer.

The present invention has been made to solve the above-mentioned problems, and prevents fluctuations in the magnetometer output caused by fluctuations in the output of the electronic circuit that constitutes the drive circuit to prevent measurement errors. The purpose is to obtain a magnetometer with less. Another object of the present invention is to eliminate the adverse effect of magnetism caused by the attitude change of the sensor block due to the turning of the airplane, the rotation of the rotating mechanism, etc., and to obtain a magnetometer with a small coefficient estimation error. Furthermore, it is intended to obtain a magnetometer that operates reliably without trapping magnetic flux.

[0024]

In a magnetometer according to the present invention, an SQUID fixed to each of a plurality of planes of a sensor block forming a predetermined angle with each other, and the SQUID described above.
A drive circuit that drives the ID, and an unknown number calculation circuit that uses an output of the drive circuit to approximate an unknown numerical value that is a function of an axis alignment error, a sensor sensitivity, and an initial magnetic flux value that is a reference of the sensor output by a polynomial. A reference signal generating circuit for generating a calibration magnetic field in a conventional magnetometer having a magnetic field calculating circuit for calculating a magnetic field to be measured using the output of the driving circuit and the output of the unknown number calculating circuit, a current source and a magnetic field generation. A coil, a bandpass filter and a comparison circuit that extracts only the reference signal for calibration from the output of the drive circuit and compares it with the reference signal, a filter that removes the calibration signal from the output of the drive circuit, the output of this filter and the above A correction circuit for correcting the output fluctuation of the magnetometer based on the output of the comparison circuit is added.

In the magnetometer according to the present invention,
An SQUID fixed to each of a plurality of planes forming a predetermined angle of the sensor block, a drive circuit that drives the SQUID, and an output that is the output of the drive circuit is used as a reference for an axis alignment error, a sensor sensitivity, and a sensor output. Conventionally provided with an unknown number calculation circuit for approximating and calculating an unknown value that is a function of the magnetic flux value with a polynomial, and a magnetic field calculation circuit for calculating the measured magnetic field using the output of the drive circuit and the output of the unknown number calculation circuit. A reference signal generating circuit for generating a calibration magnetic field in the magnetometer, a current source and a magnetic field generating coil,
A bandpass filter and a comparison circuit that extracts only the reference signal for calibration from the output of the drive circuit and compares it with the reference signal, and a calibration signal removal circuit that removes the calibration signal from the output of the drive circuit based on the output of the bandpass filter. And a correction circuit for correcting the output fluctuation of the magnetometer based on the output of the calibration signal removal circuit and the output of the comparison circuit.

In the magnetometer according to the present invention, the SQUID fixed to each of a plurality of planes forming a predetermined angle of the sensor block, the drive circuit for driving the SQUID, and the axis alignment error using the output of the drive circuit. , The unknown magnetic field which is a function of the initial magnetic flux value which is the reference of the sensor sensitivity and the sensor output is calculated by approximating an unknown numerical value with a polynomial, and the output of the driving circuit and the output of the unknown vector calculating circuit. And a magnetic field calculation circuit for generating a calibration magnetic field, and changing the direction of the magnetic field incident on the SQUID, a reference signal generation circuit, a magnetic field change current source, a magnetic field change calibration coil, and a geomagnetism. A magnetometer for measurement and a bandpass filter for extracting only a reference signal for calibration from the output of the drive circuit and comparing it with the reference signal, A comparator circuit, a calibration signal removing circuit that removes the calibration signal from the output of the drive circuit based on the output of the band pass filter, and the output fluctuation of the magnetometer based on the output of the calibration signal removing circuit and the output of the comparison circuit. A correction circuit for correcting the is added.

Further, in the magnetometer according to the present invention,
An SQUID fixed to each of a plurality of planes forming a predetermined angle of the sensor block, a drive circuit that drives the SQUID, and an output that is the output of the drive circuit is used as a reference for an axis alignment error, a sensor sensitivity, and a sensor output. Conventionally provided with an unknown number calculation circuit for approximating and calculating an unknown value that is a function of the magnetic flux value with a polynomial, and a magnetic field calculation circuit for calculating the measured magnetic field using the output of the drive circuit and the output of the unknown number calculation circuit. Of the reference signal generating circuit, which changes the direction of the magnetic field incident on the SQUID, the magnetic field changing current source, the magnetic field changing calibration coil, and the magnetometer for measuring geomagnetism, and the output of the driving circuit. From the output of the bandpass filter and the comparison circuit that extracts only the reference signal for calibration from the A calibration signal removal circuit that removes the calibration signal from the output of the drive circuit, and a correction circuit that corrects the output fluctuation of the magnetometer based on the output of this calibration signal removal circuit and the output of the above comparison circuit are added. A good / bad judgment circuit is added to notify an abnormality when the output of the circuit exceeds a certain range.

In the magnetometer according to the present invention, the SQUID fixed to each of a plurality of planes forming a predetermined angle of the sensor block, the drive circuit for driving the SQUID, and the axis alignment error using the output of the drive circuit. , The unknown magnetic field which is a function of the initial magnetic flux value which is the reference of the sensor sensitivity and the sensor output is calculated by approximating an unknown numerical value with a polynomial, and the output of the driving circuit and the output of the unknown vector calculating circuit. And a magnetic field calculation circuit for generating a calibration magnetic field, and changing the direction of the magnetic field incident on the SQUID, a reference signal generation circuit, a magnetic field change current source, a magnetic field change calibration coil, and a geomagnetism. Measurement magnetometer and bandpass filter and comparison that extracts the reference signal for calibration from the output of the drive circuit and compares it with the reference signal And a calibration signal removal circuit that removes a calibration signal from the output of the drive circuit based on the output of the bandpass filter, and the output fluctuation of the magnetometer based on the output of this calibration signal removal circuit and the output of the comparison circuit. A correction circuit for correction is added, and further a magnetic field correction circuit and a correction coil for correcting the magnetic distortion generated by the magnetic field change calibration coil are added.

In the magnetometer according to the present invention,
An SQUID fixed to each of a plurality of planes forming a predetermined angle of the sensor block, a drive circuit that drives the SQUID, and an output that is the output of the drive circuit is used as a reference for an axis alignment error, a sensor sensitivity, and a sensor output. Conventionally provided with an unknown number calculation circuit for approximating and calculating an unknown value that is a function of the magnetic flux value with a polynomial, and a magnetic field calculation circuit for calculating the measured magnetic field using the output of the drive circuit and the output of the unknown number calculation circuit. A reference signal generating circuit for generating a magnetic field for calibration in the magnetometer, changing the direction of the magnetic field incident on the SQUID, and canceling the magnetic field to zero, a canceling current source, a magnetic field change calibration coil, and a magnetometer for measuring geomagnetism. A bandpass filter and a comparison circuit for extracting only a reference signal for calibration from the output of the drive circuit and comparing the reference signal with the reference signal; A calibration signal removal circuit that removes the calibration signal from the output of the drive circuit based on the output of the filter, and a correction circuit that corrects the output fluctuation of the magnetometer based on the output of this calibration signal removal circuit and the output of the comparison circuit. It was added.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention. In the figure, 1A, 1B, 1C, 2, 3A, 3B, 3C,
4, 5 are the same as the conventional one, 6 is a reference signal generating circuit for generating a reference signal of a sine wave outside the used frequency band for calibration,
Reference numeral 7 is a current source for generating a calibration magnetic field current based on the reference signal output from the reference signal generation circuit 6, and 8 is the SQ.
A magnetic field generating coil which is arranged around the UIDs 1A, 1B and 1C and which generates a magnetic field for calibration using the output of the current source 7, 9
A, 9B and 9C are filters for removing the calibration signal from the outputs of the drive circuits 3A, 3B and 3C, 10A, 10B and 1C.
0C is a bandpass filter for extracting a calibration signal from the outputs of the drive circuits 3A, 3B, 3C, 11A, 11B, 1
1C is the bandpass filter 10A, 10B, 10C
Of the reference signal which is the output of the reference signal generating circuit 6, and 12A, 12B and 12C are correction circuits that correct the output fluctuation based on the outputs of the comparison circuits 11A, 11B and 11C. S _K is a reference signal output from the reference signal generation circuit 6, V _HA , V _HB , and V _HC are signals output from the drive circuits 3A, 3B, and 3C, V _FA , and V _FA
FB and V _FC are magnetic field measurement signals output from the filters 9A, 9B and 9C, S _BA , S _BB and S _BC are calibration signals output from the band pass filters 10A, 10B and 10C, S _OA and S _OB. , S _OC are the comparison circuits 11A, 11B,
The fluctuation signals output from 11C, Δu _m , Δv _m , and Δw
_m driving circuits 3A at time t _m, 3B, 3C _{output, Δu n, Δv n, Δw} n the time t _m after the time t _n
Output of the drive circuits 3A, 3B, 3C, K ₁ ,
K _2, ..., K ₈ is the calculated value of the unknown quantities calculation circuit 4, F is the calculated value of the magnetic field calculation circuit 5.

FIG. 2 shows the comparison circuits 11A, 11B and 11 described above.
It is the block diagram which showed the structure of C on the basis of the comparison circuit 11A. In the figure, 13A and 13B are bridge rectifier circuits for full-wave rectification, 14A and 14B are smoothing resistors, 15A,
15B, 15C and 15D are smoothing capacitors, 16A,
16B is a notch filter, 17A is a differential amplifier, S _BA is a calibration signal, S _K is a reference signal, and S _OA is the differential amplifier 17 described above.
This is a fluctuation signal output from A.

FIG. 3 shows the correction circuits 12A, 12B, 12
FIG. 9 is a block diagram showing the configuration of C as a representative of a correction circuit 12A. In the figure, 18 is a voltage dividing resistor, 19 is a FET
(Field Effect Transistor),
D, G, and S are the drain, gate, and source of the FET 19 respectively, 20A is an amplifier, V _FA is a magnetic field measurement signal, and S is S.
_OA is a fluctuating signal.

Next, the operation of the magnetometer according to the first embodiment of the present invention will be described. In the following description, assuming that the conventional magnetometer is mounted on a moving object such as an aircraft as an example, the geomagnetism is regarded as the magnetic field to be measured.

First, SQUIDs 1A, 1B and 1C are cooled by immersing them in liquid helium to transform them into superconductivity, and then SQUIDs are respectively driven by drive circuits 3A, 3B and 3C.
1A, 1B, and 1C are magnetic flux locked at the same time, and the interlinkage magnetic flux of SQUIDs 1A, 1B, and 1C at this time is the origin of the output zero, and the change amount of the interlinkage magnetic flux from there is a voltage V corresponding to the magnetic field change amount. Output as _HA , V _HB , and V _HC .

At this time, if phase fluctuations, amplitude fluctuations, etc. of the electronic circuits constituting the drive circuits 3A, 3B, 3C occur, the output signal of the magnetometer fluctuates in proportion to these fluctuations, which may cause a measurement error. However, the reference signal generating circuit 6, the current source 7, the magnetic field generating coil 8, the filters 9A, 9B, 9C,
Band pass filters 10A, 10B, 10C, comparison circuits 11A, 11B, 11C and correction circuits 12A, 12B,
12C prevents fluctuations in the output of the magnetometer and prevents measurement errors.

Specifically, the reference signal generating circuit 6 generates a sine wave reference signal S _K having a constant amplitude of several tens of kHz, other than DC to several tens of kHz in the frequency band used by the magnetometer, and the current source 7 is Based on this reference signal S _K , several tens of kHz
A sine wave current of z is generated, and the magnetic field generating coil 8 constantly applies a sine wave magnetic field having a constant amplitude of several tens of kHz to the SQUIDs 1A, 1B and 1C for calibration based on this current.

Next, the SQUIDs 1A, 1B, 1C and the drive circuits 3A, 3B, 3C add the magnitude of the external magnetic field and the sine wave magnetic field having a constant amplitude of several tens of kHz for calibration as a magnetic field measurement signal and a calibration signal, respectively. The voltage is converted into a voltage in a closed state, but only the magnetic field measurement signals V _FA , V _FB , and V _FC are taken out of this voltage signal by the filters 9A, 9B, and 9C whose high-frequency cutoff frequency is set to ten and several kHz. , The bandpass filters 10A, 10B, 10
C takes out only the calibration signals S _BA , S _BB and S _BC .

The reference signal S _K and the bandpass filter 1
The calibration signal S _BA extracted at 0 A is the bridge rectifier circuit 13A of the comparison circuit 11A and the smoothing resistor 14 respectively.
Smoothing circuit composed of A and smoothing capacitors 15A and 15B, bridge rectifier circuit 13B, smoothing resistor 14B
The DC voltage corresponding to the amplitude of the sine wave is converted by the smoothing circuit including the smoothing capacitors 15C and 15D, and the reference signal and the calibration signal converted into the DC voltage cut off only the frequency of several tens of kHz. With the notch filters 16A and 16B set as follows,
After the sine wave component is completely removed, the differential amplifier 17
The former is subtracted from the latter by A, the magnitudes of the two are compared, and the variation of the magnetometer, that is, the variation signal S _OA is output.

Similarly, the bandpass filters 10B and 10C are provided.
The calibration signals S _BB and S _BC extracted in step S11 are compared in magnitude with the reference signal converted into the DC voltage by the comparison circuits 11B and 11C, respectively, and the fluctuation amount of the magnetometer, that is, fluctuation signals S _OB and S _BC.
Output as _OC .

Next, the magnetic field measurement signal V _FA and the fluctuation signal S _OA
Are voltage dividing resistors 1 of the correction circuit 12A, respectively.
8. Input to the gate G of the FET 19 to change signal S _O
The operating resistance R _DS between the drain D and the source S of the FET 19 is controlled so as to change in inverse proportion to the voltage of the above voltage, and the operating resistance R _DS and the resistance value R _B of the voltage dividing resistor 18 are used to obtain the following equation. The voltage is divided into the partial pressure ratio K shown in (1), and the magnetic field measurement output Δu _m is output by canceling the fluctuation of the magnetometer.

[0041]

(Equation 7)

The magnetic field measurement signals V _FB and V _FC and the fluctuation signals S _OB and S _OC are also input to the correction circuits 12B and 12C, respectively, and the fluctuation amount of the magnetometer is canceled by the same method, and the magnetic field measurement output Δv _m , Output as Δw _m .

The magnetic field measurement outputs Δu _m , Δv _m , and Δw _m
Changes momentarily because the incident angle of the geomagnetism changes with the turning of the aircraft, etc., but turning or rotating with a rotating mechanism while keeping the geomagnetism H constant by raising the flight altitude sufficiently. While changing the attitude of the sensor block by using the set of outputs (Δu ₁ , Δv ₁ , Δw) of the drive circuits 3A, 3B, 3C at times t ₁ , t ₂ , ..., T ₉ .
₁ ), (Δu ₂ , Δv ₂ , Δw ₂ ), ..., (Δu ₉ , Δ
v ₉ , Δw ₉ ) is measured and sent to the unknown number calculation circuit 4. Next, in the unknown number calculation circuit 4, these nine sets of numerical values are substituted into the equation (7) to solve the simultaneous linear equations, and K ₁ , K ₂ ,
The value of K ₈ is calculated and the calculated value is sent to the magnetic field calculation circuit 5.

Next, at the time t _n after the time t _m , the outputs Δu _n , Δv _n , and Δw _n of the drive circuits 3A, 3B, and 3C.
To the magnetic field calculation circuit 5. K _1, K ₂ to the magnetic field calculator 5 (7), ..., and calculates K ₈ and Δu _n, Δv _n, F by substituting the values of _{Δw n (Δu n, Δv n} , Δw n) a. This output is used, for example, to detect a change in the earth's magnetism from a change in the value of F and discover a magnetic substance.

Second Embodiment FIG. 4 is a block diagram showing a second embodiment of the present invention. In the figure, 1A, 1B, 1C, 2, 3A, 3B, 3C,
4, 5, 6, 7, 8, 10A, 10B, 10C, 11
A, 11B, 11C, 12A, 12B and 12C are the same as those of the first embodiment, 21A, 21B and 21C are outputs of the drive circuits 3A, 3B and 3C based on the outputs of the band pass filters 10A, 10B and 10C. Is a calibration signal removal circuit that removes the calibration signal included in.

Note that V _HA , V _HB , V _HC shown in FIG.
V _FA , V _FB , V _FC , S _BA , S _BB , S _BC , S _OA , S _OB , S
_{OC, Δu m, Δv m,} Δw m, Δu n, Δv n, Δ
w _n , K ₁ , K ₂ , ..., K ₈ and F are the same as the signals described in FIG.

FIG. 5 shows the calibration signal removing circuits 21A and 21A.
It is the figure which showed the structure of B and 21C as the representative of the calibration signal removal circuit 21A. In the figure, 17B is the same differential amplifier as 17A, 20B is the same amplifier as 20A, S _BA , V
_HA is the calibration signal and the output of the drive circuit 3A, respectively.

Next, the operation of the magnetometer according to the second embodiment of the present invention will be described. First, SQUIDs 1A, 1B,
1C is cooled by immersing it in liquid helium, and then transferred to superconductivity. Then, SQUIDs 1A, 1B and 1C are magnetically locked simultaneously by drive circuits 3A, 3B and 3C, respectively.
The interlinkage magnetic flux of SQUIDs 1A, 1B, and 1C at this time is set as the origin of the output zero, and the change amount of the interlinkage magnetic flux from there is output as the voltages V _HA , V _HB , and V _HC corresponding to the magnetic field change amount.

At this time, if phase fluctuations, amplitude fluctuations, etc. of the electronic circuits constituting the drive circuits 3A, 3B, 3C occur, the output signal of the magnetometer fluctuates in proportion to these fluctuations, and a measurement error may occur. The reference signal generating circuit 6, the current source 7, the magnetic field generating coil 8 and the band pass filter 10
A, 10B, and 10C generate the reference signal S _K for calibration as in the first embodiment, and the calibration signals S _BA and S are generated.
_BB and S _BC are calculated, and the comparison circuits 11A and 11A
B and 11C show the fluctuations of the magnetometer as fluctuation signals S _OA , S _OB and S
While output as _OC , the calibration signal S _BA , the drive circuit 3
The output V _HA of A is input to the amplifier 20B and the differential amplifier 17B of the calibration signal removing circuit 21A, respectively, and the amplitude of the calibration signal S _BA is first included in the output V _HA of the drive circuit 3A. Then, the differential amplifier 17B subtracts the calibration signal with the adjusted amplitude from the output V _HA of the drive circuit 3A to obtain the output V of the drive circuit 3A.
_The calibration signal contained in _HA is removed and only the magnetic field measurement signal V _FA is taken out.

Calibration signals S _BB , S _BC and drive circuits 3A, 3
The outputs V _HB and V _{HC of} B are also respectively the calibration signal removing circuit 21.
Similarly, only the magnetic field measurement signals V _FB and V _FC included in the outputs V _HB and V _HC of the drive circuits 3A and 3B, which are input to B and 21C, are extracted.

Next, the magnetic field measurement signals V _FA , V _FB and V _FC and the fluctuation signals S _OA , S _OB and S _OC are applied to the correction circuits 12A and 1A.
2B, 12C, and the magnetic field measurement output Δ in which the fluctuation in the output of the magnetometer is canceled by the same method as in the first embodiment.
Output as u _m , Δv _m , and Δw _m .

The magnetic field measurement outputs Δu _m , Δv _m , and Δw _m
Changes from moment to moment because the incident angle of geomagnetism changes as the aircraft turns, etc., but just like in the first embodiment,
While changing the attitude of the sensor block by turning or rotating with a rotating mechanism while keeping the geomagnetism H constant by raising the flight altitude sufficiently, time t ₁ ,
t _2, ..., a drive circuit 3A in t _9, 3B, the output of 3C set _{(Δu 1, Δv 1, Δw} 1), (Δu 2, Δ
v _2, [Delta] w _2), ..., measured _{(Δu 9, Δv 9, Δw} 9), K 1, K 2 by solving the simultaneous linear equations, ..., and calculates the value of K _8, further, the magnetic field calculator According to 5, the formula (7)
The _{K 1, K 2, ...,} K 8 and time t _m after the time t _n in the driver circuit 3A, 3B, is output from the 3C (delta
Substituting the values of u _n , Δv _n , and Δw _n ) into F (Δu _n ,
Calculate Δv _n , Δw _n ). This output is, for example, F
It is used to detect changes in the earth's magnetism from changes in the value of and to discover magnetic substances.

Third Embodiment FIG. 6 is a block diagram showing a third embodiment of the present invention. In the figure, 1A, 1B, 1C, 2, 3A, 3B, 3C,
4, 5, 6, 10A, 10B, 10C, 11A, 11
B, 11C, 12A, 12B, 12C, 21A, 21
B and 21C are the same as those of the second embodiment, 22A and 22C.
B and 22C are magnetometers for measuring geomagnetism which measure three components of geomagnetism and elevation angles and azimuth angles which will be described later, and 23 are outputs of the magnetometers 22A, 22B and 22C for measuring geomagnetism and outputs of the reference signal generating circuit 6. The magnetic field changing current sources 24A, 24B and 24C for generating a current for calibrating magnetic field and a current for changing magnetic field incident angle based on
Generates a magnetic field for calibration based on the current of 3 and SQUI
A magnetic field change calibration coil that changes the direction of the magnetic field incident on D1A, 1B, and 1C. Here, the magnetic field change calibration coil is shown arranged around the SQUIDs 1A, 1B, and 1C in three orthogonal axes.

It should be noted that V shown in FIG._HA, V_HB, V_HC,
V_FA, V_FB, V_FC, S_BA, S_BB, S _BC, S_OA, S_OB, S
_OC, Δu_m, Δv_m, Δw_m, Δu_n, Δv_n, Δ
w_n, K₁, K_Two, ... K₈, F are the signals described in FIG.
Is the same as

Next, the operation of the magnetometer according to the third embodiment of the present invention will be described. First, SQUIDs 1A, 1B,
1C is cooled by immersing it in liquid helium, and then transferred to superconductivity. Then, SQUIDs 1A, 1B and 1C are magnetically locked simultaneously by drive circuits 3A, 3B and 3C, respectively.
The interlinkage magnetic flux of SQUIDs 1A, 1B, and 1C at this time is set as the origin of the output zero, and the change amount of the interlinkage magnetic flux from there is output as the voltages V _HA , V _HB , and V _HC corresponding to the magnetic field change amount.

At this time, if phase fluctuations, amplitude fluctuations, etc. of the electronic circuits constituting the drive circuits 3A, 3B, 3C occur, the output signal of the magnetometer fluctuates in proportion to these fluctuations, which may cause a measurement error. However, the magnetic field changing current source 23 generates three sets of sine wave currents of several tens of kHz of the calibration magnetic field based on the reference signal S _K of the reference signal generating circuit 6 and changes the magnetic field incident angle described later. It is designed to generate an electric current, and the magnetic field change calibration coils 24A, 24B, 2
4C is based on the current of the magnetic field changing current source 23, the calibration magnetic field and the magnetic field for changing the magnetic field incident angle described later are SQUID 1A,
1B and 1C, and these and the bandpass filters 10A, 10B, and 10C generate the reference signal S _K for calibration as in the second embodiment, and the calibration signals S _BA , S _BB , S _BC is calculated, and further, the fluctuation amounts of the magnetometer are output as fluctuation signals S _OA , S _OB , and S _{OC in the} comparison circuits 11A, 11B, and 11C, while the calibration signal S _BA and the output V of the drive circuit 3A are output. _HA is the amplifier 20B and the differential amplifier 17B of the calibration signal removal circuit 21A, respectively.
The amplitude of the calibration signal S _BA is input to the drive circuit 3A.
Of the calibration signal included in the output V _HA of the drive circuit 3A, and then the differential amplifier 17B subtracts the calibration signal of the adjusted amplitude from the output V _{HA of the} drive circuit 3A. The calibration signal contained in the output V _HA is removed and only the magnetic field measurement signal V _FA is taken out.

Calibration signals S _BB , S _BC and drive circuits 3A, 3
The outputs V _HB and V _{HC of} B are also respectively the calibration signal removing circuit 21.
Similarly, only the magnetic field measurement signals V _FB and V _FC included in the outputs V _HB and V _HC of the drive circuits 3A and 3B, which are input to B and 21C, are extracted.

Next, the magnetic field measurement signals V _FA , V _FB and V _FC and the fluctuation signals S _OA , S _OB and S _OC are applied to the correction circuits 12A and 1A.
2B, 12C, and the magnetic field measurement output Δ in which the output fluctuation of the magnetometer is canceled in the same manner as in the second embodiment.
Output as u _m , Δv _m , and Δw _m .

Here, the geomagnetism H and SQUIDs 1A, 1B,
Consider the relationship of the incident angle with 1C in an orthogonal coordinate system. FIG. 7 shows the relationship between the geomagnetism H and the xyz orthogonal coordinate system. The geomagnetism H at time t _m is represented by polar coordinates (H, Θ _m , Φ).
_When expressed by _m ), the component representations H _xm , H _ym and H _zm of the geomagnetism H in the orthogonal coordinate system have the following relationship. Here, Θ _m is the angle between the z-axis and the geomagnetism H, and Φ _m is the angle between the xz plane and the geomagnetism H. (Hereinafter, these angles are called elevation angle and azimuth angle, respectively)

[0060]

(Equation 8)

Here, C is the magnetic field change calibration coil 24A,
24B, the dimensions of 24C, proportionality constant determined by the mounting position, _{etc., I xm, I ym, I} zm each magnetic field change calibration coils 24A, 24B, by 24C, the geomagnetic components H
It is a current required to generate a magnetic field equivalent to _xm , H _ym and H _zm .

FIG. 8 shows the SQU without changing the magnitude of the geomagnetism H.
It is a figure when the incident angle which injects into ID1A, 1B, 1C is changed by (DELTA) (theta) and (DELTA) (phi) in the elevation and the azimuth direction, respectively. Geomagnetic components H _{xm + 1} , H _{ym + 1} at that time,
The currents I _{xm + 1} , I _{ym + 1} , and I _{zm + 1} required to generate H _{zm + 1} and a magnetic field equivalent thereto are expressed by equations (16) to (18).

[0063]

[Equation 9]

At this time, the currents ΔI _x , ΔI _y , and ΔI _Z required to change the incident angle in the elevation and azimuth directions by ΔΘ and ΔΦ are expressed by equations (12) to (15) and (16) to (16). 18) is represented by the equations (19) to (21).

[0065]

(Equation 10)

Therefore, in a state where the geomagnetism H is kept constant by raising the flight altitude sufficiently, for example, the magnetometers 22A, 22A for geomagnetism measurement using a fluxgate magnetometer.
B, geomagnetic component (H _x1 at time t ₁ at 22C,
H _y1 , H _z1 ), elevation angle Θ ₁ , azimuth angle Φ ₁
Is measured and sent to the magnetic field changing current source 23.

Next, the magnetic field changing current source 23 generates the above-mentioned sine wave current for the calibration magnetic field, and at the same time the equation (19)-
By (21), the currents ΔI _x , ΔI _y , and ΔI _Z required to change the incident angle by Δθ and ΔΦ are calculated moment by moment, and sent to the magnetic field change calibration coils 24A, 24B, and 24C, and the geomagnetism H is incident. Let the angle be (H _x2 , H _y2 ,
_{H z2), (H x3,} H y3, H z3), ..., (H x9, H y9, H
_z9 ) and change electrically.

In this way, the geomagnetism measuring magnetometer 22A,
22B and 22C, the magnetic field change current source 23, and the magnetic field change calibration coils 24A, 24B, and 24C are used to generate a sinusoidal magnetic field for calibration, and the incident angle of the geomagnetism H is changed electrically, at times t ₁ and t. _2, ..., a drive circuit 3A in t _9, 3B, the output of 3C set (Δu _1, Δv _1, Δw
₁ ), (Δu ₂ , Δv ₂ , Δw ₂ ), ..., (Δu ₉ , Δ
v ₉ , Δw ₉ ) is measured and sent to the unknown number calculation circuit 4.

Next, the unknown number calculation circuit 4 substitutes these nine sets of numerical values into the equation (9) to solve the simultaneous linear equations, calculates the values of K ₁ , K ₂ , ..., K ₈ , and calculates the calculated values. It is sent to the magnetic field calculation circuit 5. In the magnetic field calculation circuit 5, K ₁ and K are added to the equation (8).
_2, ..., K ₈ and time t _m after the time t _n in the driver circuit 3A, 3B, is output from the 3C (Δu _n, Δv _n,
By substituting the value of _{Δw n), F (Δu n} , Δv n, Δ
w _n ) is calculated. This output is used, for example, to detect a change in the earth's magnetism from a change in the value of F and discover a magnetic substance.

Fourth Embodiment FIG. 9 is a block diagram showing a fourth embodiment of the present invention. In the figure, 1A, 1B, 1C, 2, 3A, 3B, 3C,
4, 5, 6, 10A, 10B, 10C, 11A, 11
B, 11C, 12A, 12B, 12C, 21A, 21
B, 21C, 22A, 22B, 22C, 23, 24A,
24B and 24C are the same as those in the third embodiment, and 25 is SQUI based on the outputs of the comparison circuits 11A, 11B and 11C.
D is a pass / fail determination circuit that determines pass / fail of the circuit.

Incidentally, V _HA , V _HB , V _HC shown in FIG.
V _FA , V _FB , V _FC , S _BA , S _BB , S _BC , S _OA , S _OB , S
_{OC, Δu m, Δv m,} Δw m, Δu n, Δv n, Δ
w _n , K ₁ , K ₂ , ..., K ₈ and F are the same as the signals described in FIG.

FIG. 10 is a block diagram showing an example of the configuration of the pass / fail judgment circuit 25. In the figure, 26A, 26B, 2
6C, 26D, 26E and 26F are comparators, 27
A, 27B, 27C, 27D, 27E and 27F are reference voltage sources, and S _OA , S _OB and S _OC are fluctuation signals.

Next, the operation of the magnetometer according to the fourth embodiment of the present invention will be described. First, SQUIDs 1A, 1B,
1C is cooled by immersing it in liquid helium, and then transferred to superconductivity. Then, SQUIDs 1A, 1B and 1C are magnetically locked simultaneously by drive circuits 3A, 3B and 3C, respectively.
The interlinkage magnetic flux of SQUIDs 1A, 1B, and 1C at this time is set as the origin of the output zero, and the change amount of the interlinkage magnetic flux from there is output as the voltages V _HA , V _HB , and V _HC corresponding to the magnetic field change amount.

At this time, if phase fluctuations, amplitude fluctuations, etc. of the electronic circuits constituting the drive circuits 3A, 3B, 3C occur, the output signal of the magnetometer fluctuates in proportion to these fluctuations, which may cause a measurement error. However, the reference signal generating circuit 6, the magnetic field change current source 23, the magnetic field change calibration coils 24A and 24B,
24C and bandpass filters 10A, 10B, 10C
Accordingly, the reference signal S _K for calibration is exactly the same as in the third embodiment.
And the calibration signals S _BA , S _BB , and S _BC are calculated, and the fluctuations of the magnetometer are output as fluctuation signals S _OA , S _OB , and S _{OC by the} comparison circuits 11A, 11B, and 11C. The calibration signal removing circuits 21A, 21B, 21C
Output of drive circuits 3A, 3B, 3C by V _HA , V _HB , V
_The calibration signals S _BA , S _BB , and S _BC included in _HC are removed to extract only the magnetic field measurement signals V _FA , V _FB , and V _FC .

Next, the magnetic field measurement signals V _FA , V _FB and V _FC and the fluctuation signals S _OA , S _OB and S _OC are applied to the correction circuits 12A and 1A.
2B, 12C, and the magnetic field measurement output Δ in which the fluctuation in the output of the magnetometer is canceled by the same method as in the third embodiment.
u _m , Δv _m , and Δw _m , and the fluctuation signals S _OA , S _OB , and S _OC are output to the comparators 26A and 26B and the reference voltage sources 27A and 27B of the pass / fail judgment circuit 25, respectively.
Comparator 2, a window comparator composed of
6C, 26D and reference voltage sources 27C, 27D, window comparators, comparators 26E, 26
F and the reference voltage sources 27E and 27F, and sends them to the window comparator 27, respectively.
A and 27B, reference voltage sources 27C and 27D, reference voltage source 2
At 7E and 27F, for example, it is determined whether or not it is within the range of the lower limit value and the upper limit value that are set to 1/2 of the reference signal converted to the DC voltage and doubled. The signals V _GA , V _GB , and V _GC are set to the low level, and the SQUIDs 1A, 1B, and 1C and the drive circuits 3A and 3A, respectively.
Notify that there is an abnormality in B and 3C.

Next, magnetometers 22A and 22B for geomagnetism measurement,
22C, the magnetic field change current source 23, the magnetic field change calibration coils 24A, 24B, 24C and the unknown number calculation circuit 4 electrically change the incident angle of the geomagnetism H in exactly the same manner as in the third embodiment, thereby obtaining a simultaneous linear equation. solved K _1, K _2, ..., and calculates the value of K _8, further by the magnetic field calculator 5, K _1, K ₂ in the formula _(8), ..., K 8 and time t _m after the time t _n At drive circuits 3A, 3B, 3C
Output from the _{(Δu n, Δv n, Δw} n) by substituting the value of is calculated _{F (Δu n, Δv n,} Δw n) a. This output is used, for example, to detect a change in the earth's magnetism from a change in the value of F and discover a magnetic substance.

Fifth Embodiment FIG. 11 is a block diagram showing a fifth embodiment of the present invention. In the figure, 1A, 1B, 1C, 2, 3A, 3B, 3C,
4, 5, 6, 10A, 10B, 10C, 11A, 11
B, 11C, 12A, 12B, 12C, 21A, 21
B, 21C, 22A, 22B, 22C, 23, 24A,
24B and 24C are the same as those in the third embodiment, 28A and 2A.
8B and 28C are the magnetic field change calibration coils 24A and 24
A correction coil for correcting the magnetic distortion generated by B and 24C, and here, as an example, the above-mentioned magnetic field change calibration coil 2
4A, 24B, and 24C show the case where coils smaller in size are arranged on concentric circles. 29 uses the output of the magnetic field changing current source 23 to correct the correction coils 24A, 24
This is a magnetic field correction circuit that supplies a correction current to B and 24C.

Incidentally, V _HA , V _HB shown in FIG.
V _HC , V _FA , V _FB , V _FC , S _BA , S _BB , S _BC , S _OA , S
_{OB, S OC, Δu m,} Δv m, Δw m, Δu n, Δv n,
Δw _n , K ₁ , K ₂ , ..., K ₈ and F are the same as the signals described in FIG.

Next, the operation of the magnetometer according to the fifth embodiment of the present invention will be described. First, SQUIDs 1A, 1B,
1C is cooled by immersing it in liquid helium, and then transferred to superconductivity. Then, SQUIDs 1A, 1B and 1C are magnetically locked simultaneously by drive circuits 3A, 3B and 3C, respectively.
The interlinkage magnetic flux of SQUIDs 1A, 1B, and 1C at this time is set as the origin of the output zero, and the change amount of the interlinkage magnetic flux from there is output as the voltages V _HA , V _HB , and V _HC corresponding to the magnetic field change amount.

At this time, if phase fluctuations, amplitude fluctuations, etc. of the electronic circuits constituting the drive circuits 3A, 3B, 3C occur, the output signal of the magnetometer fluctuates in proportion to these fluctuations, which may cause a measurement error. However, the reference signal generating circuit 6, the magnetic field change current source 23, the magnetic field change calibration coils 24A and 24B,
24C and bandpass filters 10A, 10B, 10C
Accordingly, the reference signal S _K for calibration is exactly the same as in the third embodiment.
And the calibration signals S _BA , S _BB , and S _BC are calculated, and the fluctuations of the magnetometer are output as fluctuation signals S _OA , S _OB , and S _{OC by the} comparison circuits 11A, 11B, and 11C. The calibration signal removing circuits 21A, 21B, 21C
Output of drive circuits 3A, 3B, 3C by V _HA , V _HB , V
_The calibration signals S _BA , S _BB , and S _BC included in _HC are removed to extract only the magnetic field measurement signals V _FA , V _FB , and V _FC .

Next, the magnetic field measurement signals V _FA , V _FB and V _FC and the fluctuation signals S _OA , S _OB and S _OC are applied to the correction circuits 12A and 1A.
2B, 12C, and the magnetic field measurement output Δ in which the fluctuation in the output of the magnetometer is canceled by the same method as in the third embodiment.
Output as u _m , Δv _m , and Δw _m .

Next, with the geomagnetism H kept constant by raising the flight altitude sufficiently, the magnetic field change calibration coil 24A,
24B, 24C, magnetometers 22A, 22B for geomagnetic measurement,
22C, the incident angle of the geomagnetism H using the magnetic field changing current source 23 is (H _x2 , H _y2 , H _z2 ), (H _x3 , H _y3 , H _z3 ),
..., electrically change the _{(H x9, H y9, H} z9).

However, by inputting the currents ΔI _x , ΔI _y , and ΔI _z required to change the incident angle by Δθ and ΔΦ, the magnetic field change calibration coils 24A, 24B, and 24C generate a magnetic field for changing the incident angle. At this time, SQUIDs 1A, 1B,
The magnetic field in the vicinity of 1C is distorted, and the magnetic strain (Δh
_x , Δh _y , Δh _z ).

[0084]

[Equation 11]

Here, M1, M2 and M3 are constants determined by the dimensions of the magnetic field change calibration coils 24A, 24B and 24C, the mounting position, the current flowing through the coils and the like, and Δi
_{x, Δi y, Δi z} is the magnetic distortion (Δh _x, Δh _y,
Δh _z ) is a current necessary to generate a magnetic field equivalent to Δh _z ).

[0086] As a result, the time t _1, t _2, ..., a drive circuit 3A in t _9, 3B, the output of 3C set (Delta] u _1, delta
v ₁ , Δw ₁ ), (Δu ₂ , Δv ₂ , Δw ₂ ), ...,
A slight measurement error occurs in (Δu ₉ , Δv ₉ , Δw ₉ ). The correction coils 28A, 28B, 28C and the magnetic field correction circuit 29 are composed of the magnetic field change calibration coils 24A, 24B, 24.
The magnetic field correction circuit 29 first corrects the magnetic distortion generated by C. First, the magnetic field correction circuit 29 outputs the current output Δ of the magnetic field changing current source 23.
By inputting I _x , ΔI _y , and ΔI _z , equations (22) to (2
4), the correction magnetic field (−Δ
A correction current for generating h _x , −Δh _y , −Δh _z ) is sent to the correction coils 28A, 28B, 28C.

Next, the correction coils 28A, 28B, 28
C receives the correction magnetic field (−Δh _x , −
Δh _y , −Δh _z ) is generated to cancel the magnetostriction to zero.

In this way, the magnetometers 22A, 2
2B, 22C, magnetic field change current source 23, magnetic field change calibration coils 24A, 24B, 24C, correction coils 28A, 28
B, 28C and the magnetic field correction circuit 29 are used to make the incident angle of the geomagnetism H (H _x2 , H _y2 ,
_{H z2), (H x3,} H y3, H z3), ..., (H x9, H y9, H
_z9 ) and change electrically.

Next, in the same way as in the third embodiment, the simultaneous linear equations are solved in the unknown number calculation circuit 4 to obtain K ₁ , K ₂ , ...
The value of K ₈ is calculated, and further, the magnetic field calculation circuit 5 adds K ₁ , K ₂ , ..., K ₈ to the equation (8) at time t after time t _{m.
At n} , the values of (Δu _n , Δv _n , Δw _n ) output from the drive circuits 3A, 3B, and 3C are substituted, and F (Δu
_n , Δv _n , Δw _n ) is calculated. This output is used, for example, to detect a change in the earth's magnetism from a change in the value of F and discover a magnetic substance.

Sixth Embodiment FIG. 12 is a block diagram showing a sixth embodiment of the present invention. In the figure, 1A, 1B, 1C, 2, 3A, 3B, 3C,
4, 5, 6, 10A, 10B, 10C, 11A, 11
B, 11C, 12A, 12B, 12C, 21A, 21
B, 21C, 22A, 22B, 22C, 23, 24A,
24B and 24C are the same as those in the third embodiment, and 30 is the output of the reference signal generating circuit 6 and the magnetometer 22 for geomagnetism measurement.
Using the outputs of A, 22B, and 22C, the current of the calibration magnetic field, the current for changing the magnetic field incident angle, and the SQUID 1A,
When the 1B and 1C are cooled, a canceling current for generating a canceling magnetic field for canceling the earth magnetism incident on the 1B and 1C is generated and supplied to the magnetic field change calibration coils 24A, 24B and 24C.

Incidentally, V _HA , V _HB shown in FIG.
V _HC , V _FA , V _FB , V _FC , S _BA , S _BB , S _BC , S _OA , S
_{OB, S OC, Δu m,} Δv m, Δw m, Δu n, Δv n,
Δw _n , K ₁ , K ₂ , ..., K ₈ and F are the same as the signals described in FIG.

Next, the operation of the magnetometer according to the sixth embodiment of the present invention will be described. First, SQUIDs 1A, 1B,
1C is cooled by immersing it in liquid helium, and is transformed into superconductivity. At this time, since the SQUIDs 1A, 1B, and 1C directly receive the earth's magnetism and transfer to superconductivity, the magnetic flux is trapped by itself and causes a magnetic flux trap, resulting in a decrease in output voltage and deterioration in measurement sensitivity. Or, in some extreme cases, it did not work as a magnetometer, but prevent it as follows.

First, before cooling the SQUIDs 1A, 1B and 1C, the magnetometers 22A, 22B and 22C for geomagnetism measurement.
The geomagnetic components (H _x , H _y , H _z ) are measured by and are sent to the canceling current source 30.

Next, the canceling current source 30 is expressed by equations (12) to (12).
The same calculation as in (15) is performed, and the geomagnetic component (H _x ,
H _y, H _z) opposite to the geomagnetic components (-H _x, -H _y,
Currents I _x , I _y , and I _z required to generate −H _z ).
To calculate the magnetic field change calibration coils 24A, 24B, 2
Supply to 4C.

Then, the SQUIDs 1A, 1B, and 1C are simultaneously magnetic flux-locked by the drive circuits 3A, 3B, and 3C, and the interlinkage magnetic flux of the SQUIDs 1A, 1B, and 1C at this time is set as the origin of output zero, and the chain from there The change amount of the magnetic flux is output as the voltages V _HA , V _HB , and V _HC corresponding to the change amount of the magnetic field.

At this time, if phase fluctuations, amplitude fluctuations, etc. of the electronic circuits constituting the drive circuits 3A, 3B, 3C occur, the output signal of the magnetometer fluctuates in proportion to these fluctuations, which may cause a measurement error. However, the reference signal generating circuit 6, the canceling current source 23, the magnetic field change calibration coils 24A, 24B, 24
C and the band-pass filters 10A, 10B, and 10C generate the reference signal S _K for calibration and calculate the calibration signals S _BA , S _BB , and S _BC exactly as in the second embodiment.
Further, the comparison circuits 11A, 11B and 11C output the fluctuations of the magnetometer as fluctuation signals S _OA , S _OB and S _OC , while the calibration signal removal circuits 21A, 21B and 21C drive the driving circuits 3A, 3B and 3C. Of the magnetic field measurement signals V _FA , V _FB , and V _FC are removed by removing the calibration signals S _BA , S _BB , and S _BC included in the outputs V _HA , V _HB , and V _HC .

Next, the magnetic field measurement signals V _FA , V _FB and V _FC and the fluctuation signals S _OA , S _OB and S _OC are applied to the correction circuits 12A and 1A.
2B, 12C, and the magnetic field measurement output Δ in which the fluctuation in the output of the magnetometer is canceled by the same method as in the third embodiment.
Output as u _m , Δv _m , and Δw _m . The subsequent operation is the same as that of the third embodiment.

In the first to sixth embodiments, SQUID1
A, 1B, and 1C are DC-Ss that include two Josephson elements in a superconducting ring and drive by applying a DC bias current.
Although the QUID has been described as an example, an RF-SQUID that includes one Josephson element in the superconducting ring and is driven by an alternating bias current may be used.

[0099]

As described above, according to the present invention, the following effects can be obtained.

According to the present invention, S fixed on each of a plurality of planes of the sensor block forming a predetermined angle with each other.
Using the QUID, the drive circuit that drives the SQUID to obtain a desired output, and the output of the drive circuit, an unknown numerical value that is a function of the axis alignment error, the sensor sensitivity, and the initial magnetic flux value that serves as a reference for the sensor output is expressed by a polynomial. Generate a magnetic field for calibration in a conventional magnetometer equipped with an unknown number calculation circuit that approximates and calculates the magnetic field to be measured using the output of the drive circuit and the output of the unknown number calculation circuit. A reference signal generating circuit, a current source and a magnetic field generating coil,
A bandpass filter and a comparison circuit for extracting a calibration signal from the output of the drive circuit and comparing it with a reference signal, a filter for removing the calibration signal from the output of the drive circuit, and based on the output of this filter and the output of the comparison circuit. By adding a correction circuit for correcting the fluctuation of the output of the magnetometer, the fluctuation of the output of the magnetometer due to the phase fluctuation and the amplitude fluctuation of the electronic circuit is prevented, so that the magnetometer with a small measurement error can be obtained.

Further, according to the present invention, the SQUIDs fixed to each of the plurality of planes of the sensor block forming a predetermined angle, the drive circuit for driving the SQUID to obtain a desired output, and the output of the drive circuit. An unknown number calculation circuit that calculates by approximating an unknown numerical value that is a function of the initial magnetic flux value that is the reference of the axis alignment error, the sensor sensitivity and the sensor output using, and the output of the drive circuit and the output of the unknown number calculation circuit. A conventional magnetometer equipped with a magnetic field calculation circuit for calculating a magnetic field to be measured using a reference signal generation circuit for generating a magnetic field for calibration, a current source and a magnetic field generation coil, and a calibration signal from the output of the drive circuit. A bandpass filter and a comparison circuit for taking out and comparing with the reference signal, and removing the calibration signal from the output of the drive circuit based on the output of the bandpass filter. By adding a calibration signal removal circuit and a correction circuit that corrects the output variation of the magnetometer based on the output of the calibration signal removal circuit and the output of the comparison circuit, the magnetometer due to the phase variation and amplitude variation of the electronic circuit Since the output fluctuation of 1 is prevented, it is possible to obtain a magnetometer with less measurement error.

According to the present invention, S fixed on each of a plurality of planes of the sensor block forming a predetermined angle with each other.
Using the QUID, the drive circuit that drives the SQUID to obtain a desired output, and the output of the drive circuit, an unknown numerical value that is a function of the axis alignment error, the sensor sensitivity, and the initial magnetic flux value that serves as a reference for the sensor output is expressed by a polynomial. A conventional magnetometer having an unknown number calculation circuit that approximates and calculates the magnetic field to be measured using the output of the drive circuit and the output of the unknown number calculation circuit is used to generate a calibration magnetic field. And a reference signal generating circuit for changing the direction of the magnetic field incident on the SQUID, a magnetic field changing current source, a magnetic field changing calibration coil, and a magnetometer for geomagnetism measurement, and extracting only a reference signal for calibration from the output of the driving circuit as a reference. A bandpass filter and a comparison circuit for comparing with the signal, and a calibration signal removal circuit for removing the calibration signal from the output of the drive circuit based on the output of the bandpass filter. By adding a correction circuit that corrects the output fluctuation of the magnetometer based on the output of the calibration signal removal circuit and the output of the comparison circuit, the fluctuation of the magnetometer output due to the phase fluctuation and amplitude fluctuation of the electronic circuit Since it is prevented from occurring, a magnetometer with less measurement error can be obtained. Moreover, when calculating the unknown value, the magnetic field incident on the SQUID is electrically changed without depending on the attitude change of the sensor block due to the turning of the airplane or the rotation of the rotating mechanism. It is possible to obtain a magnetometer with a small coefficient estimation error by reducing the adverse effect of magnetism caused by a change in posture due to rotation of the rotating mechanism.

Further, according to the present invention, SQUIDs fixed to a plurality of planes of the sensor block which form a predetermined angle with each other, a drive circuit for driving the SQUID to obtain a desired output, and an output of the drive circuit. An unknown number calculation circuit that calculates by approximating an unknown numerical value that is a function of the initial magnetic flux value that is the reference of the axis alignment error, the sensor sensitivity and the sensor output using, and the output of the drive circuit and the output of the unknown number calculation circuit. , A reference signal generating circuit for generating a calibration magnetic field and changing the direction of the magnetic field incident on the SQUID in a conventional magnetometer having a magnetic field calculating circuit for calculating a magnetic field to be measured using , A magnetic field change calibration coil and a magnetometer for measuring geomagnetism, and a bandpass filter that extracts only the reference signal for calibration from the output of the drive circuit and compares it with the reference signal. Filter and a comparison circuit, a calibration signal removal circuit that removes a calibration signal from the output of the drive circuit based on the output of the bandpass filter, and a magnetometer based on the output of the calibration signal removal circuit and the output of the comparison circuit. By adding a correction circuit that corrects output fluctuations, and by adding a pass / fail judgment circuit that reports an abnormality when the output of the comparison circuit exceeds a certain range, Prevent the output of the magnetometer from changing,
In addition, since the abnormality is notified when the output of the comparison circuit exceeds a certain range, a magnetometer with a small measurement error can be obtained and the quality of the SQUID and the electronic circuit can be automatically determined. Also, when calculating the unknown value,
The magnetic field incident on the SQUID is electrically changed without depending on the attitude change of the sensor block due to the turning of the airplane or the rotation of the rotating mechanism. It is possible to obtain a magnetometer having a small coefficient estimation error by reducing the adverse effect of

According to the present invention, S fixed on each of a plurality of planes of the sensor block forming a predetermined angle with each other.
Using the QUID, the drive circuit that drives the SQUID to obtain a desired output, and the output of the drive circuit, an unknown numerical value that is a function of the axis alignment error, the sensor sensitivity, and the initial magnetic flux value that serves as a reference for the sensor output is expressed by a polynomial. A conventional magnetometer having an unknown number calculation circuit that approximates and calculates the magnetic field to be measured using the output of the drive circuit and the output of the unknown number calculation circuit is used to generate a calibration magnetic field. A reference signal generation circuit for changing the direction of the magnetic field incident on the SQUID, a magnetic field change current source, a magnetic field change calibration coil, and a magnetometer for geomagnetism measurement, and a reference signal for calibration taken out from the output of the drive circuit. A bandpass filter and a comparison circuit for comparing with the above, and a calibration signal removal circuit for removing the calibration signal from the output of the drive circuit based on the output of the bandpass filter. A correction circuit that corrects the output fluctuation of the magnetometer based on the output of the calibration signal removal circuit and the output of the comparison circuit is added, and further, a magnetic field correction circuit and correction that correct the magnetic distortion generated by the magnetic field change calibration coil. By adding a coil, the output fluctuations of the magnetometer due to phase fluctuations, amplitude fluctuations, etc. of the electronic circuit did not occur.
A magnetometer with less measurement error can be obtained. Further, when calculating the unknown value, without relying on the attitude change of the sensor block due to the turning of the airplane or the rotation of the rotating mechanism,
Since the magnetic field incident on the SQUID is electrically changed and magnetic distortion is not generated when the magnetic field is changed, the adverse effect of magnetism due to the attitude change due to the turning of the airplane, the rotation of the rotating mechanism, etc. is reduced and Moreover, it is possible to obtain a magnetometer with a small coefficient estimation error.

Further, according to the present invention, the SQUIDs fixed to each of the plurality of planes of the sensor block which form a predetermined angle with each other, the drive circuit for driving the SQUID to obtain a desired output, and the output of the drive circuit. An unknown number calculation circuit that calculates by approximating an unknown numerical value that is a function of the initial magnetic flux value that is the reference of the axis alignment error, the sensor sensitivity and the sensor output using, and the output of the drive circuit and the output of the unknown number calculation circuit. A reference signal for generating a calibration magnetic field in a conventional magnetometer equipped with a magnetic field calculation circuit for calculating a magnetic field to be measured by using, and changing the direction of the magnetic field incident on the SQUID and canceling the magnetic field to zero. Generation circuit,
A canceling current source, a magnetic field change calibration coil, and a magnetometer for geomagnetism measurement, a bandpass filter and a comparison circuit for extracting only a reference signal for calibration from the output of the drive circuit and comparing it with the reference signal, and an output of the bandpass filter. Based on the calibration signal removal circuit that removes the calibration signal from the output of the drive circuit,
By adding a correction circuit that corrects the output fluctuation of the magnetometer based on the output of this calibration signal removal circuit and the output of the comparison circuit, fluctuations in the output of the magnetometer due to phase fluctuations and amplitude fluctuations of the electronic circuit do not occur. Since this is done, it is possible to obtain a magnetometer with few measurement errors. Moreover, when calculating the unknown value, the magnetic field incident on the SQUID is electrically changed without depending on the attitude change of the sensor block due to the turning of the airplane or the rotation of the rotating mechanism. It is possible to obtain a magnetometer with a small coefficient estimation error by reducing the adverse effect of magnetism caused by a change in posture due to rotation of the rotating mechanism. Furthermore, when the SQUID is cooled, the magnetic field incident on the SQUID is transferred to superconductivity in a state of canceling it out to zero, so that it is possible to obtain a magnetometer that operates reliably without magnetic flux trapping.

[Brief description of drawings]

FIG. 1 is a block diagram showing Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a comparison circuit 11A.

FIG. 3 is a block diagram showing an example of a configuration of a correction circuit 12A.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

FIG. 5 is a block diagram showing an example of a configuration of a calibration signal removal circuit 21A.

FIG. 6 is a block diagram showing a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a geomagnetism H and an xyz rectangular coordinate system.

FIG. 8 is a diagram showing a relationship with the xyz orthogonal coordinate system when the incident angle of the geomagnetism H is changed by ΔΘ and ΔΦ in the elevation and azimuth directions, respectively.

FIG. 9 is a block diagram showing a fourth embodiment of the present invention.

10 is a block diagram showing an example of a configuration of a pass / fail judgment circuit 25. FIG.

FIG. 11 is a block diagram showing a fifth embodiment of the present invention.

FIG. 12 is a block diagram showing a sixth embodiment of the present invention.

FIG. 13 is a block diagram showing an example of a conventional magnetometer.

FIG. 14 is a diagram showing a relationship between an xyz rectangular coordinate system and a uvw oblique coordinate system.

FIG. 15 is a diagram showing a positional relationship between a uvw oblique coordinate system and an SQUID.

[Explanation of symbols]

 1A, 1B, 1C SQUID 2 Sensor block 3A, 3B, 3C Drive circuit 4 Unknown number calculation circuit 5 Magnetic field calculation circuit 6 Reference signal generation circuit 7 Current source 8 Magnetic field generation coil 9A, 9B, 9C filter 10A, 10B, 10C Band pass filter 11A, 11B, 11C Comparing circuit 12A, 12B, 12C Correction circuit 13A, 13B Bridge rectifying circuit 14A, 14B Smoothing resistor 15A, 15B, 15C, 15D Smoothing capacitor 16A, 16B Notch filter 17A, 17B Differential amplifier 18 Voltage Voltage dividing resistor 19 FET 20A, 20B Amplifier 21A, 21B, 21C Calibration signal removing circuit 22A, 22B, 22C Geomagnetism measuring magnetometer 23 Magnetic field changing current source 24A, 24B, 24C Magnetic field changing calibration coil 25 Pass / fail judgment circuit 26A, 26B 26C, 26D comparators 27A, 27B, 27C, 27D reference power source 28A, 28B, 28C, 28D correction coil 29 magnetic field correction circuit 30 cancels a current source

Claims (6)

[Claims] 1. A superconducting quantum interference device fixed to each of a plurality of planes forming a predetermined angle of a sensor block, and a plurality of drive circuits for driving the plurality of superconducting quantum interference devices to obtain a desired output. A reference signal generation circuit that generates a reference signal of a sine wave outside the frequency band used, a current source that generates a current for a calibration magnetic field based on the output of the reference signal generation circuit, and around the superconducting quantum interference device. A magnetic field generating coil that is arranged to generate a calibration magnetic field using the current of the current source, a plurality of filters that remove a calibration signal from the outputs of the plurality of drive circuits, and a calibration signal from the outputs of the plurality of drive circuits. A plurality of band pass filters to be taken out, a plurality of comparison circuits for comparing the output of the plurality of band pass filters with the magnitude of the reference signal of the reference signal generating circuit, and an output of the plurality of comparison circuits. A plurality of correction circuits that correct the output fluctuations of the plurality of drive circuits, and an unknown numerical value that is a function of the initial magnetic flux value that serves as a reference for the axis alignment error, the sensor sensitivity, and the sensor output using the outputs of the plurality of correction circuits. A magnetic field calculation circuit that calculates a magnetic field to be measured using the outputs of the plurality of correction circuits and the outputs of the unknown number calculation circuits. . 2. A superconducting quantum interference device fixed to each of a plurality of planes forming a predetermined angle of a sensor block, and a plurality of drive circuits for driving the plurality of superconducting quantum interference devices to obtain a desired output. A reference signal generation circuit that generates a reference signal of a sine wave outside the frequency band used, a current source that generates a current for a calibration magnetic field based on the output of the reference signal generation circuit, and around the superconducting quantum interference device. A magnetic field generating coil that is arranged to generate a calibration magnetic field using the current of the current source, a plurality of bandpass filters that extract a calibration signal from the outputs of the plurality of drive circuits, and an output of the plurality of bandpass filters. A plurality of calibration signal removal circuits for removing the calibration signals included in the output of the plurality of drive circuits,
A plurality of comparison circuits for comparing the output of the plurality of bandpass filters and the magnitude of the reference signal of the reference signal generation circuit,
A plurality of correction circuits that correct the output fluctuations of the plurality of drive circuits based on the outputs of the plurality of comparison circuits, and the outputs of the plurality of correction circuits are used as a reference for axis alignment error, sensor sensitivity, and sensor output. An unknown number calculation circuit that calculates an unknown value that is a function of the initial magnetic flux value by approximating with a polynomial, and a magnetic field calculation circuit that calculates the measured magnetic field using the outputs of the plurality of correction circuits and the output of the unknown number calculation circuit. A magnetometer characterized by having. 3. A superconducting quantum interference device fixed to each of a plurality of planes forming a predetermined angle of a sensor block, and a plurality of driving circuits for driving the plurality of superconducting quantum interference devices to obtain a desired output. Calibration based on a reference signal generation circuit that generates a sinusoidal reference signal outside the operating frequency band, a magnetometer for measuring geomagnetism, the output of the reference signal generation circuit, and the output of the magnetometer for geomagnetism measurement. And a magnetic field changing current source that generates a current for changing the magnetic field incident angle,
A magnetic field change calibration coil which is arranged around the superconducting quantum interference device and which changes the direction of the calibration magnetic field and the magnetic field incident on the superconducting quantum interference device by using the current of the magnetic field changing current source, and the plurality of drive circuits. A plurality of band pass filters that extract only the reference signal from the output of the plurality of, and a plurality of calibration signal removal circuit that removes the calibration signals included in the outputs of the plurality of drive circuits based on the outputs of the plurality of band pass filters, , A plurality of comparison circuits that compare the output of the plurality of band pass filters with the reference signal of the reference signal generation circuit, and the output fluctuations of the plurality of drive circuits are corrected based on the outputs of the plurality of comparison circuits. By using a plurality of correction circuits and the outputs of the plurality of correction circuits, an unknown numerical value that is a function of an axis alignment error, a sensor sensitivity, and an initial magnetic flux value serving as a reference of the sensor output is polynomialized. And unknowns calculation circuit approximate to calculate,
A magnetometer, comprising: a magnetic field calculation circuit for calculating a magnetic field to be measured using outputs of the plurality of correction circuits and outputs of the unknown number calculation circuit. 4. A superconducting quantum interference device fixed to each of a plurality of planes forming a predetermined angle of a sensor block, and a plurality of drive circuits for driving the plurality of superconducting quantum interference devices to obtain a desired output. Calibration based on a reference signal generation circuit that generates a sinusoidal reference signal outside the operating frequency band, a magnetometer for measuring geomagnetism, the output of the reference signal generation circuit, and the output of the magnetometer for geomagnetism measurement. And a magnetic field changing current source that generates a current for changing the magnetic field incident angle,
A magnetic field change calibration coil which is arranged around the superconducting quantum interference device and which changes the direction of the calibration magnetic field and the magnetic field incident on the superconducting quantum interference device by using the current of the magnetic field changing current source, and the plurality of drive circuits. A plurality of band pass filters that extract only the reference signal from the output of the plurality of, and a plurality of calibration signal removal circuit that removes the calibration signals included in the outputs of the plurality of drive circuits based on the outputs of the plurality of band pass filters, , A plurality of comparison circuits that compare the output of the plurality of band pass filters with the reference signal of the reference signal generation circuit, and the output fluctuations of the plurality of drive circuits are corrected based on the outputs of the plurality of comparison circuits. By using a plurality of correction circuits and the outputs of the plurality of correction circuits, an unknown numerical value that is a function of an axis alignment error, a sensor sensitivity, and an initial magnetic flux value serving as a reference of the sensor output is polynomialized. And unknowns calculation circuit approximate to calculate,
A magnetic field calculation circuit that calculates the magnetic field to be measured using the outputs of the plurality of correction circuits and the output of the unknown number calculation circuit, and whether or not the output of the plurality of comparison circuits exceeds a certain range indicates an abnormality. A magnetometer characterized by having a discrimination circuit. 5. A superconducting quantum interference device fixed to each of a plurality of planes of a sensor block forming a predetermined angle with each other, and a plurality of driving circuits for driving the plurality of superconducting quantum interference devices to obtain a desired output. Calibration based on a reference signal generation circuit that generates a sinusoidal reference signal outside the operating frequency band, a magnetometer for measuring geomagnetism, the output of the reference signal generation circuit, and the output of the magnetometer for geomagnetism measurement. And a magnetic field changing current source that generates a current for changing the magnetic field incident angle,
A magnetic field change calibration coil which is arranged around the superconducting quantum interference device and changes the direction of the calibration magnetic field and the magnetic field incident on the superconducting quantum interference device by using the current of the magnetic field change current source, and the magnetic field change calibration coil. A correction coil for correcting the magnetic distortion generated by the magnetic field correction circuit, and a magnetic field correction circuit for supplying a correction current to the correction coil by using the output of the magnetic field changing current source.
A plurality of bandpass filters for extracting only reference signals from the outputs of the plurality of drive circuits, and a plurality of removing the calibration signals contained in the outputs of the plurality of drive circuits based on the outputs of the plurality of bandpass filters. A calibration signal removal circuit,
A plurality of comparison circuits for comparing the output of the plurality of bandpass filters and the magnitude of the reference signal of the reference signal generation circuit,
A plurality of correction circuits that correct the output fluctuations of the plurality of drive circuits based on the outputs of the plurality of comparison circuits, and the outputs of the plurality of correction circuits are used as a reference for axis alignment error, sensor sensitivity, and sensor output. An unknown number calculation circuit that calculates an unknown value that is a function of the initial magnetic flux value by approximating with a polynomial, and a magnetic field calculation circuit that calculates the measured magnetic field using the outputs of the plurality of correction circuits and the output of the unknown number calculation circuit. A magnetometer characterized by having. 6. A superconducting quantum interference device fixed to each of a plurality of planes forming a predetermined angle of a sensor block, and a plurality of drive circuits for driving the plurality of superconducting quantum interference devices to obtain a desired output. Calibration based on a reference signal generation circuit that generates a sinusoidal reference signal outside the operating frequency band, a magnetometer for measuring geomagnetism, the output of the reference signal generation circuit, and the output of the magnetometer for geomagnetism measurement. Current, a current for changing magnetic field incident angle, and a canceling current source for generating a canceling current, and a calibration magnetic field and the superconducting quantum interference arranged around the superconducting quantum interference device and using the current of the current source. A magnetic field change calibration coil that changes the direction of the magnetic field incident on the element and cancels the magnetic field to zero; a plurality of bandpass filters that extract only reference signals from the outputs of the plurality of drive circuits; A plurality of calibration signal removing circuits for removing the calibration signals contained in the outputs of the plurality of drive circuits based on the outputs of the bandpass filters of the above, the outputs of the plurality of bandpass filters and the reference of the reference signal generating circuit. A plurality of comparison circuits that compare the magnitude of signals, a plurality of correction circuits that correct the output fluctuations of the plurality of drive circuits based on the outputs of the plurality of comparison circuits, and an axis that uses the outputs of the plurality of correction circuits. Alignment error, using an unknown number calculation circuit that calculates an unknown numerical value that is a function of the sensor sensitivity and the initial magnetic flux value that is the reference of the sensor output by approximating with a polynomial, and the outputs of the plurality of correction circuits and the unknown number calculation circuit And a magnetic field calculating circuit for calculating a magnetic field to be measured by a magnetometer.