Magnetic sensor analysis system, analysis method, and computer program

Abstract

This reduces errors when analyzing the output of magnetic sensors, thereby shortening the time required for calibration. [Solution] The magnetic sensor analysis system according to this disclosure comprises a plurality of calibration coils 21 arranged near a plurality of magnetic sensors 10, a coil drive device that generates a magnetic field by activating the plurality of calibration coils 21 one by one in sequence, a recording device 45 that records magnetic measurement values ​​output from each of the plurality of magnetic sensors 10 when a magnetic field is generated, a division processing unit that divides the time-series data of magnetic measurement values ​​recorded in the recording device 45 into a plurality of division sections based on the period relating to the activity of the plurality of calibration coils 21, and a display unit that displays the plurality of division sections in a visually identifiable manner in correspondence with the time-series data.

Description

[Technical Field]

[0001] The present disclosure relates to a magnetic sensor analysis system, analysis method and computer program, and particularly relates to an analysis system preferably used for calibration of a magnetic sensor. [Background Art]

[0002] In recent years, biomagnetic measurement apparatuses such as magnetoencephalographs, magnetocardiographs, and magnetomyographs that measure weak biomagnetism generated from the heart, spinal cord, peripheral nerves, and the like of a subject are sometimes used in medical sites. A biomagnetic measurement apparatus detects magnetism generated by weak currents accompanying excitation of cells constituting these organs, and is an important apparatus for diagnosis of heart diseases, neurological diseases, and the like. In biomagnetic measurement apparatuses, use of a magnetic sensor using a magnetoresistive element instead of an expensive SQUID sensor has been studied.

[0003] When actually performing biomagnetic measurement using a magnetic sensor, it is necessary to perform a calibration operation in advance in order to reduce measurement errors (see Non-Patent Document 1). In the calibration operation, a plurality of calibration coils that generate a calibration magnetic field are used, and calibration can be performed by solving an inverse problem from measurement results using a method such as the least squares method.

[0004] Regarding the technology for performing calibration of a magnetic sensor, Patent Document 1 describes a magnetic measurement apparatus including a fixing mechanism that fixes the relative positions of a magnetic sensor and a plurality of calibration coils. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2023-167848 [Non-Patent Documents]

[0006] [Non-Patent Document 1] Y. Adachi, D. Oyama, Y. Terazono, T. Hayashi, T. Shibuya and S. Kawabata, "Calibration of Room Temperature Magnetic Sensor Array for Biomagnetic Measurement," in IEEE Transactions on Magnetics, vol. 55, no. 7, pp. 1-6, July 2019, Art no. 5000506, doi: 10.1109 / TMAG.2019.2895355.(https: / / ieeexplore.ieee.org / document / 8660661) [Overview of the project] [Problems that the invention aims to solve]

[0007] The calibration process for a magnetic sensor involves an analysis process that measures the output of the magnetic sensor and analyzes the measurement results, and an estimation process that estimates the actual position and sensitivity of the magnetic sensor using the magnetic measurement values. While the latter estimation process requires considerable trial and error, errors in the initial analysis process result in repeated trial and error, even though the estimation process fails to correctly estimate the position and sensitivity of the magnetic sensor, leading to significant time and human loss. Reducing errors in the analysis process can significantly shorten the calibration time.

[0008] Therefore, the purpose of this disclosure is to provide a magnetic sensor analysis system, analysis method, and computer program that can reduce errors during output analysis of magnetic sensors and shorten the time required for calibration. [Means for solving the problem]

[0009] To solve the above problems, the magnetic sensor analysis system according to this disclosure is characterized by comprising: a plurality of calibration coils arranged near a plurality of magnetic sensors; a coil drive device that generates a magnetic field by activating the plurality of calibration coils one by one in sequence; a recording device that records magnetic measurement values ​​output from each of the plurality of magnetic sensors when the magnetic field is generated; a division processing unit that divides the time series data of the magnetic measurement values ​​recorded in the recording device into time ranges relating to the activity of the plurality of calibration coils; and a display unit that displays the division intervals of the time series data in a visually identifiable manner in correspondence with the waveform of the time series data.

[0010] According to this disclosure, the behavior of the outputs of multiple magnetic sensors can be objectively understood. Therefore, errors during the analysis of magnetic sensor outputs can be reduced, and the time required for calibration can be shortened. [Effects of the Invention]

[0011] Thus, this disclosure provides a magnetic sensor analysis system, analysis method, and computer program that can reduce errors during output analysis of magnetic sensors and shorten the time required for calibration. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a block diagram showing the configuration of the magnetic sensor analysis system 1 according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic perspective view showing the configuration of the sensor array 10A. [Figure 3] Figure 3 is a schematic diagram showing an example of the internal structure of the magnetic sensor 10. [Figure 4] Figure 4 is a schematic plan view of the sensor chip 13. [Figure 5] Figure 5 is a schematic cross-sectional view along line AA shown in Figure 4. [Figure 6] Figure 6 is a circuit diagram of the magnetic sensor 10. [Figure 7]Fig. 7 is a schematic perspective view showing an arrangement example of a plurality of calibration coils 21 with respect to a sensor array 10A. [Figure 8] Fig. 8 is a schematic plan view showing an arrangement example of a plurality of calibration coils 21 with respect to the sensor array 10A. [Figure 9] Fig. 9 is a schematic side view showing an arrangement example of a plurality of calibration coils 21 with respect to the sensor array 10A. [Figure 10] Fig. 10 is a schematic perspective view showing the configuration of a coil unit 21U. [Figure 11] Fig. 11 is a functional block diagram of an analysis system 1 for magnetic sensors. [Figure 12] Fig. 12 is a sequence diagram showing an outline of a calibration procedure for the magnetic sensor 10. [Figure 13] Fig. 13 is a screen diagram showing a first display mode 100A of time-series data of output signals of a magnetic sensor. [Figure 14] Figs. 14(a) to 14(c) are screen diagrams showing a case where an abnormality is observed in the display of divided sections in the first display mode 100A. [Figure 15] Fig. 15 is a screen diagram showing a second display mode 100B of time-series data of output signals of a magnetic sensor. [Figure 16] Fig. 16 is a screen diagram showing a third display mode 100C of time-series data of output signals of a magnetic sensor. [Figure 17] Fig. 17 is a screen diagram showing a fourth display mode 100D of time-series data of output signals of a magnetic sensor. [Figure 18] Figs. 18(a) and 18(b) are screen diagrams showing a case where an abnormality is observed in an output waveform in the fourth display mode 100D. [Figure 19] Fig. 19 is a screen diagram showing a signal waveform of a monitor channel for monitoring the voltage of the calibration coil 21. MODE FOR CARRYING OUT THE INVENTION

[0013] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings.

[0014] Figure 1 is a block diagram showing the configuration of the magnetic sensor analysis system 1 according to an embodiment of the present disclosure.

[0015] As shown in Figure 1, the magnetic sensor analysis system 1 comprises a sensor array 10A in which a plurality of magnetic sensors 10 are arranged in an array, a calibration substrate 20 having a plurality of calibration coils 21, a receiving device 40 that receives the output signals (magnetic measurement values) of each magnetic sensor 10, a recording device 45 that records the magnetic measurement values ​​of each magnetic sensor 10 and the drive signals of the calibration coils 21 received by the receiving device 40 as time-series data, and a computer 50 that takes in the magnetic measurement values ​​recorded in the recording device 45 and analyzes them.

[0016] The calibration board 20 is equipped with a generator 22 that generates drive signals for driving multiple calibration coils 21 (L1 to L24), a switch 23 that switches the destination of the drive signals, and a controller 24 that controls the generator 22 and the switch 23. The generator 22, the switch 23, and the controller 24 constitute a coil drive device 25. The controller 24 controls the generator 22 and the switch 23 according to operating conditions (parameter settings) given in advance by the computer 50. This makes it possible to activate multiple calibration coils 21 individually.

[0017] The computer 50 can be any device that has arithmetic functions, memory functions, data input functions, and display functions, and can be a desktop PC, notebook PC, tablet terminal, smartphone, etc. The computer 50 has an application program for analyzing measurement data installed, which enables the various functions described later.

[0018] Figure 2 is a schematic perspective view showing the configuration of the sensor array 10A.

[0019] As shown in Figure 2, the sensor array 10A consists of multiple magnetic sensors 10 arranged in two dimensions on the xy plane. In this example, the sensor array 10A has 6 × 7 = 42 magnetic sensors 10, but the number of magnetic sensors 10 is not particularly limited. The sensitivity axis direction of each magnetic sensor 10 is the z direction.

[0020] Figure 3 is a schematic diagram showing an example of the internal structure of the magnetic sensor 10.

[0021] As shown in Figure 3, the magnetic sensor 10 comprises a sensor housing 11 made of a non-magnetic material, a circuit board 12 housed in the sensor housing 11, and a sensor chip 13 and a magnet collector 14 mounted on the circuit board 12. The magnet collector 14 is a rod-shaped body extending in the z direction and is made of a high-permeability material such as ferrite. Of the sensor housing 11, the xy plane where one end of the magnet collector 14 in the z direction is located constitutes the sensor head H. The sensor chip 13 is positioned at the other end of the magnet collector 14 in the z direction. As a result, the z-direction signal magnetic field component emitted from the object to be measured located near the sensor head H is collected by the magnet collector 14 and applied to the sensor chip 13.

[0022] Figure 4 is a schematic plan view of the sensor chip 13, and Figure 5 is a schematic cross-sectional view along line AA shown in Figure 4.

[0023] As shown in Figures 4 and 5, four magnetoresistive elements M1 to M4 and a cancellation coil C1 are integrated on the element formation surface of the sensor chip 13. GMR elements, TMR elements, AMR elements, etc., can be used as the magnetoresistive elements M1 to M4. Alternatively, a fluxgate sensor or a magneto-impedance sensor may be used instead of the magnetoresistive elements.

[0024] The cancellation coil C1 is covered with an insulating film 15, and magnetoresistive elements M1 to M4 are formed on the insulating film 15. The magnetoresistive elements M1 to M4 are covered with an insulating film 16. The magnetizer 14 is positioned between the magnetoresistive elements M1, M2 and M3, M4 when viewed from the z direction. As a result, the magnetic field in the z direction collected by the magnetizer 14 is distributed in the +x and -x directions on the element formation surface of the sensor chip 13. Consequently, magnetic field components in opposite directions are applied to the magnetoresistive elements M1, M2 and M3, M4. Here, the fixed magnetization directions of the magnetoresistive elements M1 to M4 are all aligned in either the +x or -x direction.

[0025] Furthermore, the cancellation coil C1 is positioned to overlap with the magnetoresistive elements M1 to M4. When a cancellation current is passed through the cancellation coil C1, cancellation magnetic fields in opposite directions are applied to the magnetoresistive elements M1, M2 and M3, M4.

[0026] Figure 6 is a circuit diagram of the magnetic sensor 10.

[0027] As shown in Figure 6, the magnetoresistive elements M1 to M4 included in the magnetic sensor 10 are connected in a bridge configuration, and the differential signal generated by this configuration is supplied to the differential amplifier 17. The differential amplifier 17 generates a feedback current F based on the differential signal. The feedback current F flows through the cancellation coil C1. As a result, the cancellation coil C1 generates a cancellation magnetic field so that the differential signal component, which is the output signal of the magnetic sensor 10, becomes zero. The feedback current F is converted into a voltage by a resistor R. Then, a voltage measurement circuit 18, which measures the voltage across the resistor R, generates a detection signal Vout that is proportional to the feedback current F.

[0028] Multiple magnetic sensors 10 having this configuration are fixed to a fixing mechanism 30 shown in Figure 2. The fixing mechanism 30 has 6 × 7 = 42 insertion slots 31 arranged in an array, and a sensor array 10A is formed by inserting multiple magnetic sensors 10 into these insertion slots 31. The measuring surface of the fixing mechanism 30 forms an xy plane, and during measurement, the measuring surface is faced by the object to be measured, such as a human body. This makes it possible to detect the magnetic field distribution emitted by the object to be measured using the 42 sensor heads H located on the measuring surface.

[0029] Multiple calibration coils 21 on the calibration substrate 20 are positioned near the sensor array 10A during the calibration operation.

[0030] Figures 7 to 9 schematically show examples of the arrangement of multiple calibration coils 21 with respect to the sensor array 10A, where Figure 7 is a schematic perspective view, Figure 8 is a schematic plan view, and Figure 9 is a schematic side view. Figure 10 is a schematic perspective view showing the configuration of the coil unit 21U.

[0031] As shown in Figures 7 to 9, the sensor array 10A has multiple magnetic sensors 10 arranged at equal intervals in the X and Y directions, and for example, it has 6 × 7 = 42 magnetic sensors 10.

[0032] On the other hand, the multiple calibration coils 21 are arranged in a two-dimensional array of multiple coil units 21U in the XY direction, for example, having 8 coil units 21U. As shown in Figure 10, each coil unit 21U has 3 loop coils wound on a spherical bobbin 21B, forming 3 calibration coils 21, each facing in one of three mutually orthogonal axis directions. In other words, the coil array 21A has a total of 8 × 3 = 24 calibration coils 21.

[0033] The diameter of the loop coil (diameter of the spherical bobbin) that makes up the calibration coil 21 is, for example, 6 cm. The distance D1 between the four coil units 21U that are close to the center of the sensor array 10A is, for example, 9 cm, and the distance D2 between the four coil units 21U that are farther from the center of the sensor array 10A is, for example, 30 cm. The distance D3 from the arrangement plane of the sensor array 10A to the arrangement plane of the coil array 21A is, for example, 10 cm.

[0034] During the collection of calibration data, an alternating current is passed through each of the calibration coils 21, and the resulting magnetic field is measured by each magnetic sensor 10 to acquire magnetic field data. This operation is performed for each of the calibration coils 21, and calibration is performed for each magnetic sensor 10 by solving an inverse problem using the least squares method or the like from the magnetic field data obtained.

[0035] Specifically, the output of the magnetic sensor 10 is V meas The magnetic field generated at the position of the magnetic sensor by each calibration coil 21 is B meas In that case, B meas =g·V meas The following holds true. Here, g is the sensitivity of the magnetic sensor 10. On the other hand, since the position, tilt and sensitivity of each magnetic sensor 10 are known to some extent, the estimated magnetic field B that will be supplied from each coil to each magnetic sensor 10 is cal This can be calculated by a circular integral based on the position (x, y, z), tilt (θ, φ) and sensitivity (G) from each coil. Here, the tilt θ represents the angle in the z direction around the x-axis, and the tilt φ represents the angle in the y direction around the x-axis. Then, by performing the calculation using the least squares method so that the value E in equation (1) below is minimized, the actual position (x, y, z) and tilt (θ, φ) of the magnetic sensor 10 can be calculated.

[0036]

number

[0037] Furthermore, the actual sensitivity g of the magnetic sensor 10 can be calculated by solving equation (2) below.

[0038]

number

[0039] In this way, once the position, tilt, and sensitivity of each magnetic sensor 10 are determined, accurate magnetic measurements can be performed by correcting the actual measured values ​​based on this information. Here, in order to determine the six parameters consisting of position (x, y, z), tilt (θ, φ), and sensitivity (G), it is sufficient to have at least six calibration coils 21 within the range where the magnetic field reaches each magnetic sensor 10.

[0040] As described above, in collecting measurement data from the magnetic sensor 10, the signals output from each magnetic sensor 10 are collected as time-series data when a magnetic field is generated by activating multiple calibration coils 21 one by one in sequence. When a magnetic field is generated by the activity of the calibration coils 21, this magnetic field affects the output of each magnetic sensor 10, and the degree of this effect changes depending on the position and orientation of the calibration coils 21. In other words, if the position and orientation of the active calibration coils 21 change, the output level of each magnetic sensor 10 also changes.

[0041] The magnetic field generation operation using multiple calibration coils 21 is performed by activating each calibration coil 21 for a certain period of time, with one sequence defined as the time until all calibration coils 21 have finished activating. This is repeated multiple times (for example, 7 times), performing magnetic field generation for, for example, 7 sequences, and collecting time-series data during this process.

[0042] When activating each calibration coil 21, an alternating current (drive signal) of a predetermined frequency is supplied to the target calibration coil 21. When the supply of the drive signal to a calibration coil 21 for a certain period of time has ended, the switch 23 is flipped to start supplying the drive signal to the next calibration coil 21. In this way, when the activity of all calibration coils 21 has ended, one sequence of magnetic measurement operations for the multiple calibration coils 21 is completed, and the system moves to the next sequence. When the final sequence is completed, one magnetic measurement operation for the magnetic sensor is completed. The measurement data of the magnetic sensor is recorded in the recording device 45 and used to estimate the actual position (x, y, z), tilt (θ, φ), and sensitivity g of the magnetic sensor 10 as described above.

[0043] The measurement data from each magnetic sensor 10 recorded in the recording device 45 can be viewed on the screen. The time-series data of the magnetic measurement values ​​of each magnetic sensor 10 can be displayed for each magnetic sensor 10, and the time-series data of the magnetic measurement values ​​of multiple magnetic sensors 10 can also be displayed side by side for comparison. At this time, the intervals related to the activity of multiple calibration coils 21 are displayed in a visually identifiable manner in correspondence with the time-series data.

[0044] Figure 11 is a functional block diagram of the magnetic sensor analysis system 1.

[0045] As shown in Figure 11, the analysis system 1 according to this embodiment includes an input unit 51 that accepts input of information for setting various parameters and display operations, a data supply unit 52 that supplies time-series data of magnetic measurement values ​​of the magnetic sensor 10, an arithmetic processing unit 53 that performs data processing and image processing, a recording unit 54 that records estimated initial values ​​of the position, tilt, and sensitivity of the magnetic sensor obtained by calculation, and a display unit 55 that displays the output waveform of the magnetic sensor on a desired scale.

[0046] The arithmetic processing unit 53 also includes a division processing unit 53a that divides time-series data of magnetic measurements based on information about the activity of the calibration coil 21, a division section superimposition display processing unit 53b that superimposes the division sections onto the time-series data, a hierarchical display processing unit 53c that processes the division sections hierarchically according to the scale of the time-series data, and a parallel display processing unit 53d that generates an image for displaying multiple time-series data in parallel. These functional blocks are realized by installing a desired computer program (application software) on the computer 50.

[0047] Figure 12 is a sequence diagram showing an overview of the calibration procedure for the magnetic sensor 10.

[0048] As shown in Figure 12, the calibration of the magnetic sensor 10 involves first measuring the output of the magnetic sensor 10 (step S11), then setting the parameters necessary for output analysis (S12), and finally generating estimated initial values ​​for calibration data by preprocessing the magnetic measurement values ​​(step S13).

[0049] In the latter half of the process, initial estimated values ​​are set (step S21), calibration data is estimated through calculation (step S22), and these estimation results are applied and verified (step S23). If the estimation results are incorrect, the initial estimated values ​​are fine-tuned, the estimation process is run again, and this is repeated until appropriate estimation results are obtained (steps S21-S23).

[0050] As described above, the latter half of the calibration process (steps S21-S23) is labor-intensive, so any errors in the first half (steps S11-S13) result in significant human and time losses. Therefore, in this embodiment, the results of the preprocessing are visualized in an easy-to-understand manner to facilitate verification of the first half of the process.

[0051] Figure 13 is a screen diagram showing the first display mode 100A of the time-series data of the output signal of the magnetic sensor.

[0052] As shown in Figure 13, the first display mode 100A displays the entire output waveform of a certain magnetic sensor (e.g., Channel 0) obtained during the magnetic measurement operation from the start to the end of the magnetic measurement. The horizontal axis of the graph represents time, and the vertical axis represents the sensor output (voltage). If you want to display the output waveform of a different magnetic sensor, you can switch by selecting a different magnetic sensor on a selection screen such as a pull-down menu.

[0053] As described above, in a single magnetic measurement operation for the magnetic sensor 10, multiple calibration coils 21 are activated one by one in sequence, and one measurement sequence is completed until all calibration coils 21 have finished activating. This is repeated multiple times (for example, 7 times), performing magnetic field generation operations for, for example, 7 sequences, and during this time, magnetic measurement values ​​output from each magnetic sensor 10 are continuously collected. Therefore, the output of each magnetic sensor 10 consists of multiple (in this case, 7) sequences, and each sequence consists of multiple (in this case, 24) activity intervals of the calibration coils 21.

[0054] In the first display mode 100A, the sequence section 102 is displayed in different colors along with the output waveform 101 of the magnetic sensor. Above the output waveform 101 of the magnetic sensor, sequence numbers 102a from "1" to "7" are displayed. In this embodiment, the background color of each sequence division section is set to a different color to make the division sections visible, but the output waveform 101 itself may be color-coded according to the division section, or a highly visible boundary line may be drawn at the boundary position of the division section, and there are no particular limitations as long as the division sections are visible.

[0055] Below sequence number 102a, the activity intervals 103 of multiple calibration coils 21 are displayed in detail using different colors. This makes it easy to distinguish between the activity intervals 103 of the coils. One sequence is the period from the first to the last calibration coil 21 being activated in order, and is the sum of the activity intervals 103 of the multiple calibration coils 21. Therefore, one sequence consists of multiple coil activity intervals, and the division intervals of the time-series data of magnetic measurements have multiple layers with different time scales.

[0056] Figure 13 shows that the output of the magnetic sensor 10 increases during the activity intervals of specific calibration coils in each sequence (coils 19-21 in this example). This indicates that the magnetic sensor 10 is strongly responding to the magnetic field generated by the specific calibration coil 21. Furthermore, this trend is the same for all sequences 1-7, indicating high reproducibility of the measurement results. In this way, by superimposing the segmented intervals onto the display of the output waveform 101 of the magnetic sensor 10, the characteristics of the output of the magnetic sensor 10 can be easily grasped.

[0057] Figures 14(a) to (c) are screen diagrams showing cases where an abnormality is observed in the display of the divided section in the first display mode 100A.

[0058] The sequence interval 102 and the coil activity interval 103 are plotted based on parameter values ​​pre-entered through the input unit 51. Therefore, if there is an error in the parameter settings, for example, as shown in Figures 14(a) and (c), parts of two adjacent sequence intervals 102 may overlap, or an undefined interval may occur between two adjacent sequence intervals 102, as shown in Figures 14(b) and (c). In such cases, it is immediately apparent that the parameter settings for the sequence interval 102 are incorrect and the output of the magnetic sensor 10 cannot be evaluated correctly, allowing for an immediate review of the parameter settings.

[0059] Figure 15 is a screen diagram showing the second display mode 100B of the time-series data of the output signal of the magnetic sensor.

[0060] As shown in Figure 15, by specifying a desired sequence (e.g., the 7th sequence) in the first display mode 100A, it is possible to switch to a second display mode 100B that focuses on a specific sequence. The second display mode 100B extracts and displays a specific sequence (e.g., the 7th sequence) from the entire output waveform of a magnetic sensor (e.g., Channel 0), with the horizontal axis of the graph representing time and the vertical axis representing the sensor output. By switching from the first display mode 100A to the second display mode 100B, the hierarchy of the division interval can be switched according to the scale of the time-series data, and the data can be displayed in the same format from higher-order hierarchies to lower-order hierarchies.

[0061] As described above, one sequence consists of activity intervals of multiple (24 in this case) coils. The activity interval 103 of each coil is displayed in color superimposed on the time-series data. Above the output waveform of the magnetic sensor 10, coil numbers 103a from "1" to "24" are displayed. In this embodiment, the background color of the activity interval 103 of each coil is set to a different color to make the divided intervals visible, but the output waveform 101 may also be color-coded according to the divided interval, or a highly visible boundary line may be drawn at the boundary position of the divided interval, and there are no particular limitations as long as the divided intervals are visible. In the second display mode 100B, if you want to display the output waveform of a different sequence, you can switch by selecting a different sequence on a selection screen such as a pull-down menu.

[0062] Figure 15 shows that the output of the magnetic sensor 10 is greatest during the activity interval of the 21st coil. This indicates that the magnetic sensor 10 is responding most strongly to the magnetic field generated by the 21st coil. It can also be seen that the second greatest output of the magnetic sensor 10 occurs during the activity interval of the 19th coil, and the third greatest during the activity interval of the 20th coil.

[0063] In this way, by displaying time-series data of magnetic measurements focusing on a specific sequence, the scale of the time-series data can be enlarged, enabling detailed analysis of the time-series data. Furthermore, by superimposing the divided intervals onto the display of the output waveform 101 of the magnetic sensor 10, the characteristics of the output of the magnetic sensor 10 can be understood in detail.

[0064] When switching the hierarchy of time-series data intervals according to the scale, it is acceptable to display lower-level hierarchies in a different format than higher-level hierarchies. For example, the format of lower-level hierarchies can be changed relative to higher-level hierarchies, such as changing the color depending on the hierarchy or changing the line thickness to indicate the current hierarchy level. Such format changes make it easier to understand which hierarchy level you are currently in.

[0065] Figure 16 is a screen diagram showing the third display mode 100C of the time-series data of the output signal of the magnetic sensor.

[0066] As shown in Figure 16, by specifying the activity interval of a desired coil (e.g., the activity interval of the 24th coil) in the second display mode 100B, it is possible to switch to a third display mode 100C that focuses on the activity period of a specific coil. The third display mode 100C extracts and displays the activity interval of a specific coil (e.g., the 24th coil) from the output waveform of a magnetic sensor (e.g., Channel 0) in a specific sequence (e.g., the 7th sequence), with the horizontal axis of the graph representing time and the vertical axis representing the sensor output. By switching from the second display mode 100B to the third display mode 100C, the hierarchy of the division intervals can be switched according to the scale of the time series data, and the same format can be used to display data from higher-order hierarchies to lower-order hierarchies.

[0067] As described above, a drive signal (AC current) of a predetermined frequency (e.g., 80Hz) is supplied to the active calibration coil. The activity interval of one coil is set to an integer multiple of the period of the AC current driving the coil, and consists of the waveform periods of multiple (in this case, 18) coil drive signals. When the coil drive frequency is 80Hz, the division interval of the output waveform is 12.5ms, and the activity interval 103 of one coil is 18 × 12.5 = 1024ms.

[0068] In this way, by displaying time-series data of magnetic measurements focused on the activity interval of a specific coil, and by overlaying the waveform period of the coil drive signal onto the time-series data, the visibility of whether or not there is an abnormality in the output waveform of the magnetic sensor 10 can be improved.

[0069] As described above, the activity interval of one coil consists of multiple (18 in this case) waveform periods 105 of coil drive signals, and each waveform period 105 is superimposed on the time-series data and displayed in different colors. Above the output waveform of the magnetic sensor 10, waveform period numbers 105a from "1" to "18" are displayed. In this embodiment, the background color of each waveform period 105 is set to a different color to make the divided sections visible, but the output waveform 101 may also be color-coded according to the divided sections, or a highly visible boundary line may be drawn at the boundary position of the divided sections, and there are no particular limitations as long as the divided sections are visible. In the third display mode 100C, if you want to display the output waveform of the activity interval of another coil, you can switch by selecting the activity interval of another coil on a selection screen such as a pull-down menu.

[0070] As can be seen in Figure 16, the signal waveform of the magnetic sensor 10 during the activity interval of the 24th coil in the 7th sequence is generally uniform, although there is some variation, indicating that there is no abnormality.

[0071] In this way, by displaying time-series data of magnetic measurements focusing on the activity interval of a specific coil, the scale of the time-series data can be enlarged, enabling detailed analysis of the time-series data. Furthermore, by superimposing the divided intervals onto the display of the output waveform 101 of the magnetic sensor 10, the characteristics of the output of the magnetic sensor 10 can be understood in detail.

[0072] Figure 17 is a screen diagram showing the fourth display mode 100D of the time-series data of the output signal of the magnetic sensor.

[0073] As shown in Figure 17, the fourth display mode 100D extracts and compares the interval periods of a specific calibration coil from the output waveforms of each sequence of a certain magnetic sensor (e.g., Channel 0). That is, it displays the output waveforms during the activity intervals of a specific (e.g., the 19th) calibration coil present in each of the 1st to 7th sequences. The seven output waveforms 101-1 to 101-7 in the figure correspond to the output waveforms of the 1st to 7th sequences, from top to bottom, and are color-coded according to the corresponding sequence intervals. In this embodiment, the divided intervals of the waveform period of the coil drive signal are not superimposed on the time-series data, but similar to Figure 16, the divided intervals of the waveform periods of the 1st to 18th coil drive signals may be superimposed on the time-series data.

[0074] In this embodiment, the activity interval of one calibration coil (e.g., the 19th coil) is displayed, but it is also possible to display the activity intervals of multiple coils (e.g., the 19th to 21st coils). Furthermore, in this embodiment, multiple output waveforms 101-1 to 101-7 with different sequence intervals but a common coil activity interval are displayed side by side on a single screen, but the common element is not limited to the coil activity interval. It is also possible to display multiple output waveforms with different magnetic sensors but a common sequence interval on a single screen.

[0075] Figures 18(a) and (b) are screen diagrams showing cases where an abnormality is observed in the output waveform in the fourth display mode 100D.

[0076] For example, in the output screen shown in Figure 18(a), the amplitude fluctuation of output waveform 101-4 in the fourth sequence is finer than in the other sequences, indicating that an anomaly has occurred in output waveform 101-4 of the fourth sequence. Similarly, in the output screen shown in Figure 18(b), the amplitude fluctuations of all output waveforms 101-1 to 101-7 in the first to seventh sequences are finer, indicating that anomalies in the output waveforms have occurred in all sequences. In this way, by displaying the time-series data of a specific magnetic coil during its activity period measured in each sequence, it is possible to check at a glance whether there are coil activity periods with low reproducibility in each sequence.

[0077] Figure 19 is a screen view showing the signal waveform of the monitor channel that monitors the voltage of the calibration coil 21.

[0078] As shown in Figure 19, a drive signal (AC current) of a predetermined frequency is applied to the calibration coil 21 during the activity period, and the voltage of the calibration coil 21 can be measured via the monitor channel 22m shown in Figure 1. As described above, the activity period of one coil is set to an integer multiple of the period of the AC current driving the coil, and consists of the waveform periods of multiple (in this case, 24) coil drive signals. When the coil drive frequency is 80 Hz, the division interval of the output waveform is 12.5 ms, and the activity period 103 of one coil is 12.5 × 24 = 1024 ms.

[0079] The output screen in Figure 19 is the screen when a monitor channel is selected instead of a magnetic sensor in the first display mode 100A shown in Figure 13, and the screen configuration is the same except for the change in the signal waveform. Therefore, by specifying a desired sequence in the first display mode 100A, it is possible to switch to a second display mode 100B (not shown here) that focuses on a specific sequence. Furthermore, by specifying the activity interval of a desired coil in the second display mode 100B, it is possible to switch to a third display mode 100C that focuses on the activity period of a specific coil.

[0080] By monitoring changes in the voltage or current of the calibration coil 21, the start timing of the waveform period of the coil drive signal can be determined. For example, a threshold can be set for the coil drive signal, and the timing at which the signal crosses the threshold can be defined as the start timing of the waveform period. Therefore, the start timing of the session period and the coil activity period can be appropriately set based on pre-set activity intervals of a single coil, the number of coils, the frequency of the coil drive signal, etc.

[0081] While preferred embodiments of this disclosure have been described above, it goes without saying that this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of this disclosure, and such modifications are also included within the scope of this disclosure.

[0082] For example, the structure, number and arrangement of the magnetic sensor 10, the structure, number and arrangement of the calibration coil 21, the operating conditions of the calibration coil 21, and the layout of the display screen for the output waveform of the magnetic sensor 10 are all just examples, and various other configurations can be adopted.

[0083] The technology relating to this disclosure includes, but is not limited to, the following configuration examples.

[0084] The magnetic sensor analysis system according to this disclosure is characterized by comprising: a plurality of calibration coils arranged near a plurality of magnetic sensors; a coil drive device that generates a magnetic field by activating the plurality of calibration coils one by one in sequence; a recording device that records magnetic measurement values ​​output from each of the plurality of magnetic sensors when the magnetic field is generated; a division processing unit that divides the time-series data of the magnetic measurement values ​​recorded in the recording device into a plurality of division sections based on the period relating to the activity of the plurality of calibration coils; and a display unit that displays the plurality of division sections in a visually identifiable manner in correspondence with the time-series data.

[0085] According to this disclosure, it is possible to objectively understand the time-dependent changes in the magnetic measurement values ​​of a magnetic sensor. Therefore, it is possible to reduce errors during output analysis of the magnetic sensor and shorten the time required for calibration.

[0086] In this disclosure, the magnetic measurement operation of the plurality of magnetic sensors includes at least one measurement sequence in which the plurality of calibration coils are activated one by one in sequence to generate a magnetic field, and the division processing unit may set the division intervals based on the activity intervals of each calibration coil. This makes it possible to display the output waveform of the magnetic sensor in correspondence with the activity interval of the calibration coil, and to visually grasp the relationship between the activity interval of the calibration coil and the behavior of the output of the magnetic sensor.

[0087] The activity interval of each calibration coil is an integer multiple of the period of the calibration coil drive signal, and the division processing unit may set the division interval based on the period of the calibration coil drive signal. In this way, by displaying the waveform period of the coil drive signal superimposed on the time-series data, the visibility of whether or not there is an abnormality in the output waveform of the magnetic sensor can be improved.

[0088] The division processing unit may set the activity interval of the calibration coil and the period of the calibration coil drive signal based on changes in the voltage or current of the calibration coil. This makes it possible to determine the start timing of the waveform period of the coil drive signal. Therefore, based on a pre-set activity interval of one coil, the number of coils, the frequency of the coil drive signal, etc., the start timing of the session interval and the activity interval of the coils can be appropriately set, and the output waveform can be synchronized with the input signal.

[0089] The measurement operation of the multiple magnetic sensors may involve repeating the measurement sequence multiple times, and the division processing unit may set the division intervals based on the measurement sequence. In this way, by superimposing the sequence intervals onto the display of the output waveforms of the magnetic sensors, the characteristics of the output of the magnetic sensors can be easily grasped.

[0090] The division interval has multiple layers with different time scales, and the display unit may switch the layer of the division interval according to the scale of the time series data, or it may display from higher-order layers to lower-order layers in the same format. In this way, by displaying the time series data of magnetic measurement values ​​from higher-order layers to lower-order layers, and by superimposing the division interval on the display of the output waveform of the magnetic sensor, the characteristics of the output of the magnetic sensor can be grasped in detail.

[0091] The aforementioned division interval has multiple layers with different time scales, and the display unit switches the layer of the division interval according to the scale of the time series data, and may also display lower-order layers in a different format than higher-order layers. By changing the format of lower-order layers in relation to higher-order layers in this way, it is possible to more clearly indicate which layer the user is currently in.

[0092] The display unit may display multiple time-series data after division, which are common in certain elements and distinct in other elements, side by side on a single screen. In this case, the display unit may also display multiple time-series data where the activity interval of the calibration coil is common but the measurement sequence is different. This makes it possible to check at a glance whether there is an activity interval of the coil with low reproducibility in each sequence.

[0093] The display unit may display different background colors for different division sections, display different colors for output waveforms in different division sections, or display boundary lines at the boundaries of the division sections. In any case, the visibility of the division sections for time-series data can be improved.

[0094] Furthermore, the magnetic sensor analysis method according to this disclosure is characterized by comprising the steps of: arranging a plurality of calibration coils near the plurality of magnetic sensors; activating the plurality of calibration coils one by one in sequence to generate a magnetic field; recording the magnetic measurement values ​​output from each of the plurality of magnetic sensors when the magnetic field is generated; dividing the time-series data of the magnetic measurement values ​​into a plurality of division intervals based on the period relating to the activity of the plurality of calibration coils; and displaying the plurality of division intervals in a visually identifiable manner in correspondence with the time-series data.

[0095] According to this disclosure, it is possible to objectively understand the time-dependent changes in the magnetic measurement values ​​of a magnetic sensor. Therefore, it is possible to reduce errors during output analysis of the magnetic sensor and shorten the time required for calibration.

[0096] Furthermore, the computer program according to this disclosure is characterized in that it causes the computer to function as the division processing unit and the display unit in the magnetic sensor analysis system according to this disclosure described above. This makes it possible to analyze the output of the magnetic sensor using a computer and to objectively grasp the time change of the magnetic measurement value of the magnetic sensor. Therefore, it is possible to reduce errors during the analysis of the output of the magnetic sensor and shorten the time required for calibration. [Explanation of Symbols]

[0097] 1. Analysis System 10 Magnetic Sensors 10A Sensor Array 11 Sensor housing 12 Circuit boards 13 Sensor chips 14 Magnetic collector 15 Insulating film 16 Insulating film 17 Differential Amplifier 18 Voltage Measurement Circuit 20 Calibration boards 21 Calibration coil 21A Coil Array 21B Spherical Bobbin 21U Coil Unit 22 Generators 22m monitor channel 23 switches 24 controllers 25 Coil drive device 30 Fixing mechanism 31 Insertion port 40 Receiving device 45 Recording device 50 Computers 51 Input section 52 Data Supply Unit 53 Arithmetic Processing Unit 53a Partition Processing Unit 53b Section Overlay Display Processing Unit 53c Hierarchical display processing unit 53d Parallel display processing unit 54 Records Department 55 Display section 100A First display mode 100B Second display mode 100C Third display mode 100D 4th display mode 101, 101-1~101-7 Output waveform 102 Sequence interval 102a Sequence number 103 Coil activity interval 103a Coil number 105 Waveform period 105a Waveform period number C1 Cancel Coil F Feedback Current H Sensor Head M1~M4 Magnetoresistive elements R resistance

Claims

1. A system that measures the output of multiple magnetic sensors and analyzes the measurement results, Multiple calibration coils arranged near the aforementioned multiple magnetic sensors, A coil drive device that generates a magnetic field by activating the aforementioned plurality of calibration coils one by one in sequence, A recording device that records magnetic measurement values ​​output from each of the plurality of magnetic sensors when the aforementioned magnetic field is generated, A division processing unit that divides the time-series data of the magnetic measurement values ​​recorded in the recording device into multiple division sections based on the period relating to the activity of the multiple calibration coils, A magnetic sensor analysis system characterized by comprising a display unit that displays the plurality of division sections in a visually identifiable manner in correspondence with the time-series data of the magnetic measurement values.

2. The magnetic measurement operation of the plurality of magnetic sensors includes at least one measurement sequence in which the plurality of calibration coils are activated one by one in sequence to generate a magnetic field. The magnetic sensor analysis system according to claim 1, wherein the division processing unit sets the division interval based on the activity interval of each calibration coil.

3. The activity interval of each calibration coil is an integer multiple of the period of the drive signal for the calibration coil. The magnetic sensor analysis system according to claim 2, wherein the division processing unit sets the division interval based on the period of the drive signal of the calibration coil.

4. The magnetic sensor analysis system according to claim 3, wherein the division processing unit sets the activity interval of the calibration coil and the period of the drive signal of the calibration coil based on a change in the voltage or current of the calibration coil.

5. The measurement operation of the plurality of magnetic sensors is performed by repeating the measurement sequence multiple times. The magnetic sensor analysis system according to claim 2, wherein the division processing unit sets the division interval based on the measurement sequence.

6. The aforementioned division interval has multiple layers with different time scales, The magnetic sensor analysis system according to claim 1, wherein the display unit switches the hierarchy of the division interval according to the scale of the time series data and displays the hierarchy from higher to lower levels in the same format.

7. The aforementioned division interval has multiple layers with different time scales, The magnetic sensor analysis system according to claim 1, wherein the display unit switches the hierarchy of the division interval according to the scale of the time series data and displays the lower-order hierarchy in a different format from the higher-order hierarchy.

8. The magnetic sensor analysis system according to claim 1, wherein the display unit displays multiple time-series data after division, which are common in a specific element and distinguishable in another element, arranged on a single screen.

9. The magnetic sensor analysis system according to claim 5, wherein the display unit displays a plurality of time-series data in which the activity interval of the calibration coil is common and the measurement sequence is different.

10. The magnetic sensor analysis system according to claim 1, wherein the display unit displays the background colors of different division sections in different colors.

11. The magnetic sensor analysis system according to claim 1, wherein the display unit displays output waveforms in different division sections in different colors.

12. The magnetic sensor analysis system according to claim 1, wherein the display unit displays boundary lines at the boundaries of the divided sections.

13. A method for analyzing the outputs of multiple magnetic sensors, The steps include arranging multiple calibration coils near the multiple magnetic sensors, The steps include: activating the aforementioned plurality of calibration coils one by one in sequence to generate a magnetic field; The steps include recording the magnetic measurement values ​​output from each of the plurality of magnetic sensors when the magnetic field is generated, The steps include dividing the time-series data of the magnetic measurement values ​​into multiple division intervals based on the period relating to the activity of the multiple calibration coils, A method for analyzing a magnetic sensor, characterized by comprising the step of displaying the plurality of division intervals in a visually identifiable manner in association with the time-series data.

14. A computer program for causing a computer to function as the division processing unit and the display unit in the analysis system described in any one of claims 1 to 12.

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