JP3331374B2 - Magnetometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetometer used in geomagnetism, and more particularly to a magnetometer for measuring a magnetic field using a superconducting quantum interference device.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a configuration of a conventional magnetometer, wherein 1 is a superconducting quantum interference device, and 2 is a drive circuit. FIG. 6 is an explanatory view showing the configuration of the superconducting quantum interference device 1, wherein 3 is a superconducting ring, 4 is a Josephson junction, 5 is a modulation feedback coil, and 6 is a bias current supply line.

The superconducting quantum interference device 1 is driven by a driving circuit 2 in a known flux locked loop. As a result, the drive circuit 2 is driven by the superconducting ring 3 in the magnetic field.
And outputs only the projection component perpendicular to the surface as a magnetic field.

[0004]

SUMMARY OF THE INVENTION Superconducting quantum interference device 1
When used in a magnetic field of the order of terrestrial magnetism, a plurality of magnetic fluxes are captured inside the superconducting ring 3 which is a component thereof. The captured magnetic flux is not fixed at the initial position, but moves discontinuously in the ring due to a stochastic phenomenon such as noise mixed into the circuit. The movement of the magnetic flux appears in the form of offset noise in the output of the magnetometer, and there is a problem that the output of the magnetometer becomes inaccurate because it cannot be distinguished from a change in the magnetic field to be detected.

In addition, the above phenomenon has a problem that its occurrence is stochastic and cannot be predicted by a function because it cannot be predicted.

The present invention has been made to solve such a problem, and has as its object to provide a magnetometer capable of accurately measuring a magnetic field even under a strong magnetic field.

[0007] Other objects and novel features of the present invention will be clarified in embodiments described later.

[0008]

In order to achieve the above object, a magnetometer according to a first aspect of the present invention comprises three or more superconducting quantum interference devices having the same sensitivity, arranged in the same direction, and Is measured, and the respective magnetic fields are compared to detect a non-common magnetic field change exceeding the noise level in the output of each magnetometer to determine whether an abnormality has occurred.

That is, a magnetometer according to a first aspect of the present invention has a configuration in which a magnetic field is measured using a superconducting quantum interference device.
Three or more superconducting quantum interference elements having the same sensitivity and pointing in the same direction, driving circuits for driving the same number of superconducting quantum interference elements as the superconducting quantum interference elements, and a magnetometer for each driving circuit It is characterized by comprising a comparator for comparing all two combinations of outputs, and a logic circuit for outputting a logical product of all two combinations of outputs of each comparator.

In a magnetometer according to a second aspect of the invention, three or more superconducting quantum interference devices having the same sensitivity are arranged in the same direction,
Simultaneously measure the magnetic field and compare each magnetic field to detect a non-common magnetic field change exceeding the noise level in each magnetometer output, determine whether an abnormality has occurred,
Identify the abnormal superconducting quantum interference device, calculate the difference between the remaining normal magnetometer output and the abnormal magnetometer output, and correct the difference by subtracting the difference from the abnormal magnetometer output. Is what you do.

That is, a magnetometer according to a second aspect of the present invention has a configuration in which a magnetic field is measured using a superconducting quantum interference device.
Three or more superconducting quantum interference elements having the same sensitivity and pointing in the same direction, driving circuits for driving the same number of superconducting quantum interference elements as the superconducting quantum interference elements, and a magnetometer for each driving circuit A comparator that compares all two combinations of outputs, a logic circuit that outputs a logical product of all two combinations of outputs of each comparator, and a subtractor that calculates all two magnetometer output differences of each drive circuit A compensator that updates a compensation value based on the output of the subtractor that determines the magnetometer output difference between the drive circuit specified by the output of the logic circuit and another drive circuit; and the compensator. And another subtracter for subtracting the output of the above-mentioned driving circuit from the output of the specified driving circuit.

In the magnetometer according to the third aspect of the present invention, the same sensitivity of 3
A superconducting quantum interference device group in which at least two superconducting quantum interference devices are arranged in the same direction is arranged in three orthogonal axes, and the magnetic field is measured at the same time. The absolute value of the magnetic field is calculated from the total output. The absolute value of this magnetic field is calculated for all combinations, the median value of the absolute value of the magnetic field is taken, the median value of the absolute value of the magnetic field is compared with the absolute value of each magnetic field, and the non-common magnetic field exceeding the noise level is calculated. The change is detected to determine whether an abnormality has occurred.

That is, a magnetometer according to a third aspect of the present invention is configured to measure a magnetic field using a superconducting quantum interference device.
A sensor block in which three sets of three or more superconducting quantum interference elements having the same sensitivity and oriented in the same direction are arranged in directions orthogonal to each other, and the same number of superconducting quantum interference elements as the superconducting quantum interference elements. A driving circuit to be driven, a three-axis synthesizer that extracts the outputs of the driving circuits in the respective orthogonal directions for all combinations one by one in each direction, and synthesizes and calculates the absolute value of the magnetic field; A median value calculator that calculates the median values of all outputs, a comparator that compares the output of the median value calculator with all values of the three-axis synthesizer, and a specific combination of outputs of the comparator. And a logic circuit for outputting an output.

[0014] In the magnetometer according to the fourth aspect of the invention, the same sensitivity of 3
A superconducting quantum interference device group in which at least two superconducting quantum interference devices are arranged in the same direction is arranged in three orthogonal axes, and the magnetic field is measured at the same time. The absolute value of the magnetic field is calculated from the total output. The absolute value of this magnetic field is calculated for all combinations, the median value of the absolute value of the magnetic field is taken, the median value of the absolute value of the magnetic field is compared with the absolute value of each magnetic field, and the non-common magnetic field exceeding the noise level is calculated. Detect the change, determine whether an abnormality has occurred, determine the superconducting quantum interference device in which the abnormality has occurred from the combination of the absolute values of the magnetic field in which the abnormality has occurred, and determine the remaining normal magnetometer output Is corrected by subtracting the difference from the magnetometer output in which the abnormality has occurred.

That is, a magnetometer according to a fourth aspect of the present invention has a configuration in which a magnetic field is measured using a superconducting quantum interference device.
A sensor block in which three sets of three or more superconducting quantum interference elements having the same sensitivity and oriented in the same direction are arranged in directions orthogonal to each other, and the same number of superconducting quantum interference elements as the superconducting quantum interference elements. A driving circuit to be driven, a three-axis synthesizer that extracts the outputs of the driving circuits in the respective orthogonal directions for all combinations one by one in each direction, and synthesizes and calculates the absolute value of the magnetic field; A median value calculator that calculates the median values of all outputs, a comparator that compares the output of the median value calculator with all values of the three-axis synthesizer, and a specific combination of outputs of the comparator. A correction circuit for updating a correction value for an output of the drive circuit specified by the output of the logic circuit; a correction value calculator for outputting a correction value to the correction device; and the correction device. It is characterized in that a subtractor for subtracting the output from the output of the specified driving circuit.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a magnetometer according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows a first embodiment of a magnetometer according to the present invention. Embodiment 1
Uses three superconducting quantum interference devices, but the same applies when four or more superconducting quantum interference devices are used. In FIG. 1, reference numeral 7 denotes a first superconducting quantum interference device, 8 denotes a second superconducting quantum interference device, 9 denotes a third superconducting quantum interference device, 10 denotes a first driving circuit, and 11 denotes a second driving circuit. Drive circuit,
12 is a third drive circuit, 13 is a first comparator that logically generates a true output when the absolute value of the difference between the two inputs exceeds a certain set value, and 14 is a first comparator that calculates the difference between the two inputs. A second comparator 15, which generates a logically true output when the absolute value exceeds a certain set value, is logically true when the absolute value of the difference between the two inputs exceeds a certain set value. Third to generate output
, 16 is a first logical circuit that takes a logical product, 17 is a second logical circuit that takes a logical product, and 18 is a third logical circuit that takes a logical product.
19 is a first magnetometer output, 20 is a second magnetometer output, 21 is a third magnetometer output, 22 is an abnormality determination signal of the first superconducting quantum interference device 7, and 23 is a first magnetometer output signal. Reference numeral 24 denotes an abnormality determination signal of the superconducting quantum interference device 8, and reference numeral 24 denotes an abnormality determination signal of the third superconducting quantum interference device 9. The superconducting quantum interference devices 7, 8, and 9 have the same sensitivity and face the same direction. Further, the first comparator 13, the second comparator 14, and the third comparator 15 are provided with driving circuits 10, 11, 12 in the preceding stage.
Are set slightly higher than the noise level of.

When there is no abnormality in each superconducting quantum interference device, the superconducting quantum interference device 7 and the superconducting quantum interference device 8
And the superconducting quantum interference device 9 face the same direction, and therefore detect the same magnetic field. Therefore, the first drive circuit 1
0, the second drive circuit 11 and the third drive circuit 12 output the same value, so that the first comparator 13 and the second comparator 1
The fourth and third comparators 15 each output a false logic output.

On the other hand, it is assumed that the magnetic flux moves for some reason in the superconducting ring 3 of the first superconducting quantum interference device 7 during the measurement. In this case, the output of the first drive circuit 10 is different from those of the other two drive circuits. Therefore, the first comparator 13 and the second comparator 14 connected to the first drive circuit 10 generate a true output, and only the output of the third comparator 15 becomes a false output. In the case of the true / false combination of the comparator, the first logic circuit 1
Only the logical product of 6 outputs a true output, and the second logical circuit 17 and the third logical circuit 18 output a false output.

From the above, the signal 22 which is the output of the first logic circuit 16 is an index indicating the abnormality of the first superconducting quantum interference device 7. For the second superconducting quantum interference device 8 and the third superconducting quantum interference device 9, the signal 23,
It can be determined from the signal 24 that an abnormality has occurred.

Embodiment 2 FIG. FIG. 2 shows a second embodiment of a magnetometer according to the present invention. Embodiment 2
Uses three superconducting quantum interference devices, but the same applies when four or more superconducting quantum interference devices are used. In FIG. 2, 25 is a first subtractor, 26 is a second subtractor, 27 is a third subtractor, 28 is a first corrector, 29
Is a second compensator, 30 is a third compensator, 31 is a fourth subtractor, 32 is a fifth subtractor, 33 is a sixth subtractor, and 34 is a first calibrated magnetic force. The meter output, 35 is the second calibrated magnetometer output, and 36 is the third calibrated magnetometer output. Other components are the same as those in FIG.

A case where no abnormality occurs in each superconducting quantum interference device is considered as an initial state. Since the superconducting quantum interference device 7, superconducting quantum interference device 8, and superconducting quantum interference device 9 face the same direction, they detect the same magnetic field. Further, the first corrector 28, the second corrector 29, and the third corrector 30
The initial value of the output is 0. Therefore, the first drive circuit 1
0, the second drive circuit 11 and the third drive circuit 12 output the same value, and the fourth subtractor 31, the fifth subtractor 32 and the sixth subtractor 33 also output the same value. . Therefore, the first comparator 13, the second comparator 14, and the third comparator 15 each output a false logical output.

In this state, the first superconducting quantum interference device 7
Suppose that the magnetic flux moves in the superconducting ring 3 for some reason. In this case, the output of the first drive circuit 10 is different from those of the other two drive circuits. Therefore, the first comparator 13 and the second comparator 14 connected to the first drive circuit 10 output true, and the third comparator 1
Only the output of 5 will be false. In the case of this combination of outputs from the comparators, only the logical product of the first logic circuit 16 becomes a true output, and the second logic circuit 17 and the third logic circuit 18 become false outputs. The first subtractor 25 outputs the difference between the output of the drive circuit 10 and the output of the second drive circuit 11, and gives the value to the first corrector 28. The first compensator 28 has a first
Receiving the true output of the logic circuit 16 and adding the held previous correction value and the output value of the subtracter 25, updating the addition result as a correction value, and outputting the result to the fourth subtractor 31. .
The fourth subtractor 31 subtracts the output from the first drive circuit 10 and the correction value from the first corrector 28, and outputs the magnetometer output 19
And outputs a calibrated magnetometer output 34.

When the above operation is performed, the first comparator 13
Becomes false, the output of the first logic circuit 16 becomes false, and the first corrector 28 holds the final correction value. As a result, the first compensator 28 keeps correcting the output of the first drive circuit 10 with the correction value determined as described above until the movement of the magnetic flux next occurs, so that an accurate magnetometer output can be held.

The calibrated magnetometer outputs 35 and 36 can be obtained for the second superconducting quantum interference device 8 and the third superconducting quantum interference device 9 by the same operation.

As described above, an accurate magnetometer output can always be obtained by mutually complementing the magnetometer outputs of the superconducting quantum interference device in which an abnormality has occurred.

Embodiment 3 FIG. 3 shows a third embodiment of a magnetometer according to the present invention. Embodiment 3
Uses nine superconducting quantum interference devices, but the same applies when nine or more superconducting quantum interference devices are used. In FIG. 3, reference numeral 37 denotes a superconducting quantum interference device having an X-axis of 1,
38 is a superconducting quantum interference device of X-axis 2, 39 is a superconducting quantum interference device of X-axis 3, 40 is a superconducting quantum interference device of Y-axis 1, 41 is a superconducting quantum interference device of Y-axis 2, and 42 is Y axis 3
, 43 denotes a Z-axis 1 superconducting quantum interference device, 44 denotes a Z-axis 2 superconducting quantum interference device, and 45 denotes a Z-axis 3 superconducting quantum interference device. The superconducting quantum interference devices in the X, Y, and Z axes all have the same sensitivity, and the superconducting quantum interference devices 37 to 39 are in the X-axis direction and superconducting quantum interference devices 40 to 4.
2, the superconducting quantum interference devices 43 to 45 are oriented in the Z-axis direction, and the X, Y, and Z axes are orthogonal to each other. 46 is a drive circuit for driving the X-axis 1 superconducting quantum interference device, 47 is an X-axis drive circuit group composed of three drive circuits respectively corresponding to the three X-axis superconducting quantum interference devices, 48 Is a Y-axis drive circuit group including three drive circuits respectively corresponding to three Y-axis superconducting quantum interference devices;
Reference numeral 49 denotes a Z-axis drive circuit group including three drive circuits respectively corresponding to the three Z-axis superconducting quantum interference devices. 5
0 is a three-axis synthesizer that calculates the absolute value of the magnetic field based on a total of three orthogonal magnetometer outputs, one from each of the X-axis drive circuit group 47, the Y-axis drive circuit group 48, and the Z-axis drive circuit group 49. Numeral 51 indicates that the three-axis synthesizer 50 is connected to the X-axis driving circuit group 47 and Y
This is a three-axis synthesizer group including a total of 27 three-axis synthesizers corresponding to all orthogonal combinations of the axis drive circuit group 48 and the Z-axis drive circuit group 49. A median value calculator 52 calculates a median value of the data of the three-axis composite group 51.
3 is an output of the median value calculator 52 and a group of three-axis synthesizers 51
Are a group of comparators that logically generate a true output when the absolute value of the difference between the respective outputs exceeds a certain set value. Also,
Numeral 54 denotes a logic circuit, which has logical product circuit sections for calculating the logical product of nine comparator outputs related to the same superconducting quantum interference device among the outputs of the comparator group 53 for the number of superconducting quantum interference devices. A function of specifying the superconducting quantum interference device in which an abnormality has occurred by calculating the logical product of the outputs of the nine comparators related to each superconducting quantum interference device. Reference numeral 55 denotes a sensor block including the superconducting quantum interference devices 37 to 45 having three orthogonal axes, and reference numeral 56 denotes a magnetometer output.

The combination in which the logic circuit 54 detects an abnormality is determined as follows. The logic circuit 54 has one corresponding AND circuit unit and its logic output for each superconducting quantum interference device. In this example, since nine superconducting quantum interference devices are used, the logic output of the logic circuit 54 is 9
Individual. The X-axis 1 superconducting quantum interference device 37 is input to nine nine-axis synthesizers in the three-axis synthesizer group 51 through a drive circuit 46 for driving the X-axis 1 superconducting quantum interference device. After these nine outputs pass through comparator group 53,
It is input to certain nine input terminals of the logic circuit 54. The logical product of these nine inputs is taken by the corresponding logical product circuit,
The output of the logic circuit 54 is set so as to output a true output in the case of true and output a false output in the case of false, so that a logical output corresponding to the superconducting quantum interference device 37 on the X axis 1 is obtained. Similarly, for the remaining superconducting quantum interference devices 38 to 45, the logic circuit 5
By setting each of the outputs of Nos. 4 and 4, the combination in which the logic circuit 54 detects an abnormality is set.

First, consider the case where the superconducting quantum interference devices 37 to 45 operate normally. X-axis drive circuit group 47,
The Y-axis drive circuit group 48 and the Z-axis drive circuit group 49 output a total of nine accurate magnetic fields. Here, the values of the three orthogonal magnetic fields can be converted to the absolute value of the magnetic field by taking the square root after taking the sum of squares. Further, a slight deviation from the orthogonality of the superconducting quantum interference devices 37 to 45 can be corrected by a constant determined in advance. By inputting in advance the correction constants for all combinations of the three orthogonal axes into the three-axis synthesizer group 51, the three-axis synthesizer group 51 becomes a combination of all three orthogonal axes of the superconducting quantum interference devices 37 to 45. Then, the absolute value of the magnetic field is calculated for a total of 27 magnetic fields. When the superconducting quantum interference devices 37 to 45 operate normally, the absolute values of the magnetic fields output from the three-axis synthesizer group 51 all have the same value. The median calculator 52 is the 27 of the three-axis synthesizer group 51.
Calculate the median value of the outputs. The comparator group 53 compares the output of the median calculator 52 with the value of the three-axis synthesizer group 51, and generates a true output when the absolute value of the difference between them is equal to or greater than a preset threshold. When the superconducting quantum interference devices 37 to 45 are operating normally, the three-axis synthesizer group 51 shows the same value.
Output are all false outputs. The logic circuit 54 receives all false outputs of the comparator group 53 and outputs all false outputs. Therefore, when the superconducting quantum interference devices 37 to 45 are operating normally, all nine outputs of the logic circuit 54 are false outputs. The magnetometer output 56 has a normal magnetic field value.

Here, it is assumed that an abnormality has occurred in the superconducting quantum interference device 37. In this case, only the driving circuit 47 has an error in the magnetometer output. Therefore, among the three-axis synthesizer group 51, the outputs of the nine magnetometers involving the drive circuit 47 show values different from the other 18 outputs. Since the median calculator 52 calculates the median of all the output values of the three-axis synthesizer group 51, the median value is the fourteenth value from the larger or smaller one when considering the 27 medians. Since the abnormal values are all biased toward the larger or smaller than the normal values and the number is nine, the fourteenth data surely indicates the normal value. Therefore, the value indicated by the median calculator 52 surely becomes a normal value. When all the outputs of the three-axis synthesizer group 51 are compared with the outputs of the median value calculator 52 by the comparator group 53, only the nine outputs involving the drive circuit 47 become true. Since the combination of the truth judgment of the logic circuit 54 is set so that a logic output is obtained for each drive circuit as described above, when the output is compared with the output of the comparator group 53, it corresponds to the superconducting quantum interference device 37. The output of the logic circuit 54 becomes a true output, so that it is possible to detect that an abnormality has occurred.

The detection of an abnormality in a superconducting quantum interference device other than the superconducting quantum interference device 37 can be detected by the same logic. As described above, when an abnormality occurs in any one of the superconducting quantum interference devices 37 to 45, the occurrence of the abnormality can be detected.

Embodiment 4 FIG. FIG. 4 shows a fourth embodiment of the magnetometer according to the present invention. Embodiment 4
Uses nine superconducting quantum interference devices, but the same applies when nine or more superconducting quantum interference devices are used. In FIG. 4, 57 is a correction value calculator, 58 is a correction value calculator group, 59 is a corrector, 60 is a corrector group, 61 is a subtractor, and 62 is a subtractor group. And 63 is the calibrated magnetometer output. Other components are exactly the same as those in FIG.

First, consider the case where the superconducting quantum interference devices 37 to 45 operate normally. X-axis drive circuit group 47,
The Y-axis drive circuit group 48 and the Z-axis drive circuit group 49 output a total of nine accurate magnetic fields. Here, the values of the three orthogonal magnetic fields can be converted to the absolute value of the magnetic field by taking the square root after taking the sum of squares. Further, a slight deviation from the orthogonality of the superconducting quantum interference devices 37 to 45 can be corrected by a constant determined in advance. By inputting in advance the correction constants for all combinations of the three orthogonal axes into the three-axis synthesizer group 51, the three-axis synthesizer group 51 becomes a combination of all three orthogonal axes of the superconducting quantum interference devices 37 to 45. Then, the absolute value of the magnetic field is calculated for a total of 27 magnetic fields. When the superconducting quantum interference devices 37 to 45 operate normally, the absolute values of the magnetic fields output from the three-axis synthesizer group 51 all have the same value. The median calculator 52 is the 27 of the three-axis synthesizer group 51.
Calculate the median value of the outputs. The comparator group 53 compares the output of the median calculator 52 with the value of the three-axis synthesizer group 51, and generates a true output when the absolute value of the difference between them is equal to or greater than a preset threshold. When the superconducting quantum interference devices 37 to 45 are operating normally, the three-axis synthesizer group 51 shows the same value.
Output are all false outputs. The logic circuit 54 receives all false outputs of the comparator group 53 and outputs all false outputs. Therefore, when the superconducting quantum interference devices 37 to 45 are operating normally, all nine outputs of the logic circuit 54 are false outputs. The correction value calculator group 58 corresponds to a correction value for causing each output of the three-axis synthesizer group 51 to be the value of the median calculator 52, and corresponds to the drive circuit output of the superconducting quantum interference devices 37 to 45. The data is output to the corrector group 60. When the superconducting quantum interference devices 37 to 45 operate normally, a value of the degree of noise of the circuit is output. The corrector group 60 outputs a correction value held therein. The initial value is 0, and when the output from the logic circuit 54 is true,
The sum of the held value and the output of the correction value calculator group 58 is updated as the internally held value.

When the superconducting quantum interference devices 37 to 45 are operating normally, the outputs of the logic circuit 54 are all false outputs, so that the corrector group 60 outputs the value held therein as it is. . The output of the corrector group 60 is subtracted from the outputs of the X-axis drive circuit group 47, the Y-axis drive circuit group 48, and the Z-axis drive circuit group 49 by the subtractor group 62. Since the values held by the corrector group 60 in the initial state are normal, the magnetometer output 63 outputs a normal magnetic field value.

Here, it is assumed that an abnormality has occurred in the superconducting quantum interference device 37. In this case, only the driving circuit 47 has an error in the magnetometer output. Therefore, among the three-axis synthesizer group 51, the outputs of the nine magnetometers involving the drive circuit 47 show values different from the other 18 outputs. Since the median calculator 52 calculates the median of all the output values of the three-axis synthesizer group 51, the median value is the fourteenth value from the larger or smaller one in the case of 27 pieces. Since the abnormal values are all biased toward the larger or smaller than the normal values and the number is nine, the fourteenth data surely indicates the normal value. Therefore, the value indicated by the median calculator 52 surely becomes a normal value. Three-axis synthesizer group 5 by comparator group 53
Comparing all outputs of 1 with the output of the median value calculator 52, only the nine outputs involving the drive circuit 47 are true. Since the combination of the authenticity determination of the logic circuit 54 is set as described above, the logic circuit 5 corresponding to the superconducting quantum interference device 37 is compared with the output of the comparator group 53.
4 becomes a true output, detects that an abnormality has occurred in the superconducting quantum interference device 37, and makes only the output to the corrector 59 true, and makes the output of the corrector group 60 to the other correctors false. I do. At the same time, the correction value calculator 57 obtains the superconducting quantum interference device 3 from the outputs of the three-axis synthesizer 50 and the median calculator 52.
7 is calculated and output. When receiving the true signal of the logic circuit 54, the corrector 59 calculates the sum of the correction value calculator 59 and the internally held value, updates the internally held value, and outputs the updated value. The corrector 59 of the corrector group 60
Otherwise, since the output of the logic circuit 54 is false, the value held inside is output as it is. The subtractor group 62 outputs the output of the corrector group 60 to the X-axis drive circuit group 47 and the Y-axis drive circuit group 4
8 and the Z-axis drive circuit group 49. Here, the output of the drive circuit 46 is updated to a normal value because the updated correction value of the corrector 59 is subtracted by the subtractor 61. Therefore, the calibrated magnetometer output 63 is automatically corrected to a normal value even if the operation of the superconducting quantum interference device 37 becomes abnormal.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. There will be.

[0037]

As described above, according to the first aspect, three or more superconducting quantum interference devices having the same sensitivity are arranged in the same direction, and the magnetic fields are measured at the same time. By comparing non-common magnetic field changes exceeding the noise level in each magnetometer output, it is possible to detect the occurrence of an abnormality in one superconducting quantum interference device, thereby improving the reliability of the magnetic field measurement. be able to.

According to the second aspect of the invention, three or more superconducting quantum interference devices having the same sensitivity are arranged in the same direction, the magnetic fields are measured at the same time, and the respective magnetic fields are compared. Detect the unusual magnetic field change exceeding the noise level in the magnetometer output, determine whether an abnormality has occurred, identify the superconducting quantum interference device in which the abnormality has occurred, and compare the remaining normal magnetometer output with the normal magnetometer output. Take the difference from the abnormal magnetometer output,
Correction is performed by subtracting the difference from the magnetometer output where the abnormality has occurred. Therefore, even if an abnormality occurs in one superconducting quantum interference device during measurement of the magnetic field, it can be automatically corrected, and a high-precision magnetic field can be obtained. Can be detected.

According to the third aspect of the invention, a superconducting quantum interference device group in which three or more superconducting quantum interference devices having the same sensitivity are arranged in the same direction is arranged in three orthogonal axes, and a magnetic field is simultaneously applied. In the measurement, even if an abnormality occurs in one superconducting quantum interference device during the measurement, the occurrence of the abnormality can be detected, and the reliability of the magnetic field measurement can be improved.

According to the fourth aspect, a superconducting quantum interference element group in which three or more superconducting quantum interference elements having the same sensitivity are arranged in the same direction is arranged in three orthogonal axes, and a magnetic field is simultaneously applied. When measuring, even if an abnormality occurs in one superconducting quantum interference device during the measurement, it is automatically corrected,
High-precision magnetic field detection becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a magnetometer according to the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a third embodiment of the present invention.

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

FIG. 5 is a block diagram showing a configuration for driving a conventional superconducting quantum interference device.

FIG. 6 is an explanatory diagram illustrating a configuration of a superconducting quantum interference device.

[Description of Signs] 1 Superconducting quantum interference device 2 Drive circuit 3 Superconducting ring 4 Josephson junction 5 Modulation feedback coil 6 Bias current supply line 7 First superconducting quantum interference device 8 Second superconducting quantum interference device 9 3rd superconducting quantum interference device 10 1st drive circuit 11 2nd drive circuit 12 3rd drive circuit 13 1st comparator 14 2nd comparator 15 3rd comparator 16 1st logic circuit 17 Second logic circuit 18 Third logic circuit 19 First magnetometer output 20 Second magnetometer output 21 Third magnetometer output 22 Abnormality determination signal of first superconducting quantum interference device 7 23 Second Abnormality determination signal of superconducting quantum interference device 8 of No. 24 Abnormality determination signal of third superconducting quantum interference device 9 25 First subtractor 26 Second subtractor 27 Third subtractor 28 First corrector 29 Second corrector 30 Third Corrector 31 Fourth Subtractor 32 Fifth Subtractor 33 Sixth Subtractor 34 First Calibrated Magnetometer Output 35 Second Calibrated Magnetometer Output 36 Third Calibrated Magnetometer Output 37 Superconducting quantum interference device of X axis 1 38 Superconducting quantum interference device of X axis 2 39 Superconducting quantum interference device of X axis 3 40 Superconducting quantum interference device of Y axis 1 41 Superconducting quantum interference device of Y axis 2 42 Superconducting quantum interference device of Y axis 3 43 Superconducting quantum interference device of Z axis 1 44 Superconducting quantum interference device of Z axis 2 45 Superconducting quantum interference device of Z axis 3 46 Superconducting quantum interference device of X axis 1 Drive circuit 47 X-axis drive circuit group 48 Y-axis drive circuit group 49 Z-axis drive circuit group 50 3-axis synthesizer 51 3-axis synthesizer group 52 median calculator 53 comparator group 54 logic circuit 55 sensor block 56 magnetic force Total output 57 Positive values calculator 58 correction value calculator group 59 corrector 60 corrects instrument group 61 subtractor 62 subtractor group 63 calibrated magnetometer output

Claims (4)

(57) [Claims] 1. A magnetometer for measuring a magnetic field using a superconducting quantum interference device, comprising: three or more superconducting quantum interference devices having the same sensitivity and oriented in the same direction; A drive circuit for driving each of the same number of superconducting quantum interference devices, a comparator for comparing all two combinations of magnetometer outputs of each drive circuit, and a logical product of all two combinations of each comparator output A magnetometer, comprising: a logic circuit for outputting. 2. A magnetometer for measuring a magnetic field using a superconducting quantum interference device, comprising: three or more superconducting quantum interference devices having the same sensitivity and oriented in the same direction; A drive circuit for driving each of the same number of superconducting quantum interference devices, a comparator for comparing all two combinations of magnetometer outputs of each drive circuit, and a logical product of all two combinations of each comparator output A logic circuit for outputting, and a subtractor for calculating a difference between all two magnetometer outputs of each drive circuit;
A compensator that updates a correction value based on the output of the subtractor that determines the magnetometer output difference between the drive circuit specified by the output of the logic circuit and another drive circuit, and an output of the compensator And another subtracter for subtracting the output from the specified output of the driving circuit. 3. A magnetometer for measuring a magnetic field using a superconducting quantum interference device, wherein three or more superconducting quantum interference devices having the same sensitivity and oriented in the same direction are arranged in three sets in directions orthogonal to each other. The sensor block and the driving circuits for driving the same number of the superconducting quantum interference elements as the superconducting quantum interference elements, and the outputs of the driving circuits in the respective orthogonal directions are taken out for all combinations, one for each direction, A three-axis synthesizer that calculates the absolute value of the magnetic field by combining, a median value calculator that calculates the median values of all outputs of the three-axis synthesizers, an output of the median value calculator, and the three-axis synthesizer And a logic circuit for outputting an output for a specific combination of the outputs of the comparators. 4. A magnetometer for measuring a magnetic field using a superconducting quantum interference device, wherein three or more superconducting quantum interference devices having the same sensitivity and oriented in the same direction are arranged in three sets in directions orthogonal to each other. The sensor block and the driving circuits for driving the same number of the superconducting quantum interference elements as the superconducting quantum interference elements, and the outputs of the driving circuits in the respective orthogonal directions are taken out for all combinations, one for each direction, A three-axis synthesizer that calculates the absolute value of the magnetic field by combining, a median value calculator that calculates the median values of all outputs of the three-axis synthesizers, an output of the median value calculator, and the three-axis synthesizer A comparator that compares all the values of the above, a logic circuit that outputs an output for a specific combination of outputs of the comparator, and a correction value for the output of the drive circuit specified by the output of the logic circuit. A magnetic force, comprising: a new corrector, a correction value calculator that outputs a correction value to the corrector, and a subtractor that subtracts the output of the corrector from the output of the specified drive circuit. Total.