JP2018169361A - Magnetic measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly accurate and highly sensitive magnetic measuring device 10. SOLUTION: A sensor head unit 12 having an amorphous wire 22 having magnetic anisotropy, a digital delay pulse generator 44 and a control circuit 42 for generating a pulse signal for energizing the sensor head unit 12, and a sensor head unit. The amorphous wire 22 includes detection coils 26 and 28 for measuring the magnetic field generated by 12, and a control circuit 42 that detects the electromotive force of the detection coils 26 and 28 in synchronization with the energization of the sensor head portion 12. The pulse signal is energized, the electromotive forces ETC1 and ETC2 of the detection coils 26 and 28 are generated due to the fluctuation of the magnetic field generated by the amorphous wire 22, and the pulse signal DP1 changes from the low potential side to the high potential side, and The magnetism is detected based on the change of the electromotive forces ETC1 and ETC2 of the detection coils 26 and 28 based on at least one of the change from the high potential side to the low potential side. [Selection diagram] Fig. 2

Description

  The present invention relates to a magnetic measurement device, and more particularly to a magnetic measurement device that detects magnetism based on a change in magnetic moment in a material having magnetic anisotropy.

  For example, research on a magnetic measurement device for performing high-sensitivity magnetism measurement in a dimension such as picotesla and nanotesla has been widely performed. For example, a superconducting quantum interference device (SQUID) or a magnetic impedance A magnetic measuring device using a sensor (MI sensor) has been proposed.

  Among these, the magnetic measuring device using SQUID uses the superconducting Josephson effect and the superconducting coil, and is a large-scale device for maintaining an ultra-low temperature for realizing superconductivity, and densely shielding the environmental magnetic field. For this reason, there is a problem that a facility is required.

  On the other hand, in the magnetic sensor using the MI sensor, the current conduction path (skin effect) in the conductor surface layer portion, which occurs when a high frequency alternating current is applied to an MI (Magnetoimpedance) element, is highly influenced by an external magnetic field. Since the MI effect is used, the sensor uses a phenomenon that changes depending on the frequency of the alternating current. In addition, there is an advantage that a large-scale device or facility such as the above-described magnetic measurement device using the SQUID is not required.

  By the way, the inventor of the present invention applied a transient direct current (step pulse-like current) to a magnetic material having magnetic anisotropy such as an amorphous wire used as the MI element, or to a conductor close to the magnetic material. It was found that when a current is applied, the magnetic material generates a magnetic field, and that the generated magnetic field varies depending on the strength of the magnetic field around the magnetic material. Thus, the magnetic field generated by the magnetic material is generated even when the stepped current pulse is one, that is, even when the current is applied for a certain period of time and then is not supplied, so an alternating current is applied to the MI element. This is essentially different from the MI effect that causes a change in impedance when energized.

JP 2003-004830 A International Publication No. 2005/019851 JP 2010-256109 A International Publication No. 2009/130814 JP 2012-185103 A

Uchiyama, T .; , Nakayama, S .; Mohri, K .; Bushida, K .; , "Biomagnetic field detection using very high sensitive MI sensor for medical application, Physica Status Solidi A-Applications 6: 206. Nakayama, S .; , Atsuta, S .; Shinmi, T .; Uchiyama, T .; , "Pulse-driven magnetoimpedance sensor detection of biomagnetic fields in Musculars with Spontaneous electrical activity, 27" Biosensors and Bioelectrics and Biosciences. Nakayama, S .; , Sawamura, K .; Mohri, K .; Uchiyama, T .; , "Pulse-drive magnetoimpedance sensor detection of cardiac magnetic activity", PLOS ONE, 2011, 6 (10), e25834. Mello LGC, Menard D, Yellow A, Ding L, Saez S, Dolabdjian C, “Optimization of the magnetic ensemble sig- nals of the world. Magnetic sensor science and engineering (supplement) Yoshio Toshio Corona, pp1-181 (2016)

The present invention has been made on the basis of such knowledge, and its object is to use a magnetic material having magnetic anisotropy and enable a simpler configuration while enabling accurate measurement. The object is to provide a magnetic measuring device.

  The inventors of the present application indicate that the magnetic material having magnetic anisotropy changes the orientation of its internal magnetization between a state in which no magnetic field is applied from the surroundings and a state in which an external magnetic field to be measured is applied. It has been found that when a certain amount of current is passed through a conductor placed near the magnetized material, the internal magnetization of the magnetic material (near the conductor current axis) is aligned along the induced magnetic field. (Current induced para-axial magnetization alignment: IPA effect). Furthermore, when a direct current is applied intermittently to a magnetic material having magnetic anisotropy (specifically, an amorphous metal wire), a similar detection coil electromotive force is obtained, so that it is arranged in the vicinity. It is thought that a wire-like structure that exhibits the same action as the wire exists inside the magnetic material, suggesting that the internal magnetization of the nearby magnetic material is aligned. Therefore, this effect corresponds to a pseudo IPA effect (Fig. 4 etc.). The present invention has been made based on such findings.

  That is, the gist of the present invention for achieving the above object is as follows: (a) a sensor head unit and an energization unit that generates an intermittent DC current (stepped pulse) for energizing the sensor head unit. And a detection coil for measuring a magnetic field generated in the sensor head unit, and a detection unit that detects an electromotive force of the detection coil in synchronization with energization of the sensor head unit by the energization unit. (B) the sensor head unit includes a magnetic body having magnetic anisotropy, and (c) the energization unit includes the magnetic body having magnetic anisotropy or the magnetic anisotropy. The pulse signal is passed through a conducting wire provided along the magnetic body, and (d) the detection coil generates an electromotive force due to a change in a magnetic field generated by the magnetic body having the magnetic anisotropy. (E) Magnetic detection based on a change in electromotive force of the detection coil based on at least one of the intermittent DC current changing from the small current side to the large current side and from the large current side to the small current side It has the calculating part which performs.

  According to the magnetic measurement apparatus of the present invention, a sensor head unit having a magnetic body having magnetic anisotropy, and an intermittent DC current for energizing the sensor head unit, that is, energization for generating a stepped pulse signal. And a detection coil for measuring a magnetic field generated by the sensor head unit, and a detection unit for detecting an electromotive force of the detection coil in synchronization with energization of the sensor head unit by the energization device. In the measurement device, the intermittent direct current is passed through the magnetic body having the magnetic anisotropy or the conductive wire provided along the magnetic body having the magnetic anisotropy from the energization unit, and in the detection coil, An electromotive force is generated due to the fluctuation of the magnetic field generated by the magnetic material having the magnetic anisotropy, and the intermittent DC current is changed from the small current side to the large current side by the calculation unit. In addition, since the magnetism is detected based on the change in the electromotive force of the detection coil based on at least one of the change from the large current side to the small current side, the magnetic measurement is performed with high accuracy and the sensor size is reduced. Is realized.

  Preferably, the calculation unit includes the detection coil based on the fact that the intermittent direct current has changed from the small current side to the large current side and the change from the large current side to the small current side following the change. Magnetism is detected based on the change in the electromotive force. In this way, the intermittent DC current is changed from the small current side to the large current side, and the change from the large current side to the small current side following the change is regarded as a pair. Based on the above, it is possible to perform an operation such as subtracting or summing the amplitude and area of the change in electromotive force of the detection coil.

  Preferably, a pair of the sensor head units and a pair of the detection coils corresponding to the pair of sensor head units are provided, and the calculation unit performs differential or amplification on the outputs of the pair of detection coils. Magnetic detection is performed. In this way, magnetic measurement using a pair of sensor heads as a differential or a combination is possible.

  Preferably, the apparatus has a storage unit for storing past calculation results, and the calculation unit detects a magnetism by subtracting or amplifying a current calculation result and a past calculation result stored in the storage unit. Is to do. In this way, even when there is only one sensor head, it is possible to perform an operation such as differential or summing sensor outputs obtained in different temporal environments. In reality, even when the external magnetic field is canceled to 0 using a bias coil, the electromotive force of the detection coil is constant, that is, does not become linear with respect to the time axis. The electromotive force is greatly amplified and cannot be AD converted, resulting in bit dropping. Therefore, if the signals recorded in advance are differentiated, the entire coil electromotive force can be greatly amplified, so that signal degradation due to bit loss can be reduced.

  Preferably, the detection coil is provided so as to surround the sensor head portion and the detection target inside the detection coil. In this way, it is possible to reduce the size of the apparatus by providing the detection target and the sensor head part in the detection coil.

  Further preferably, the intermittent DC current generated by the energization section can be changed in the time when it is on the large current side. In this way, the magnitude of the magnetic field generated from the sensor head unit can be appropriately changed to a desired value by changing the time on the large current side in the intermittent direct current.

  Preferably, the magnetic body having magnetic anisotropy is an amorphous material. If it does in this way, a desired effect can be acquired by sending an electric current through the amorphous material or the conducting wire arranged along the amorphous material. Further, when a direct current is directly applied to the amorphous metal material, a good pseudo effect can be obtained by a material having a good axial conduction site inside the amorphous metal material.

  Preferably, the magnetic body having magnetic anisotropy is in any form of solid, liquid, gas or vapor. If it does in this way, a sensor head part can be constituted by giving a degree of freedom to a shape using solid, liquid, gas, or a magnetic body constituted by the above.

  Preferably, the magnetic measurement device further includes an oscillating magnetic field generating unit that applies an oscillating magnetic field to a measurement target, and the detection unit is synchronized with the vibration of the oscillating magnetic field generated by the oscillating magnetic field generating unit. The electromotive force of the detection coil is detected. In this way, a resonance phenomenon or the like in a relatively low magnetic field can be detected.

  More preferably, the magnetic measurement device includes a magnetic field generation unit that is installed in the vicinity of the sensor head unit and generates a magnetic field that is in the same direction or orthogonal to a current that is supplied to the sensor head unit. The magnetic measurement characteristic is adjusted by generating a magnetic field synchronized with a current supplied to the sensor head unit 12. In this way, when the sensor head unit has a plurality of sensor heads, for example, the magnetic field from the magnetic field generation unit is intermittently modulated by applying the magnetic field from the magnetic field generation unit to at least one sensor head. It becomes an (adjustment) signal, and sensitivity can be adjusted for each sensor head. For example, when a gradio sensor having two sensor heads is constructed, an effective differential amplification effect can be obtained by correcting the sensitivity of one sensor head. In addition, a material having magnetic anisotropy due to application of electromagnetic waves having a wide range of wavelengths can adjust sensitivity and detection characteristics according to changes in the state of internal magnetization.

  More preferably, the magnetic measurement device has a sensor head mounting portion for mounting the sensor head portion, and the sensor head mounting portion is a relative position between the sensor head portion and the magnetic field generation unit, that is, a distance, The angle can be changed. In this way, it is possible to correct the sensitivity of the sensor head and to effectively measure changes when the distance, angle, etc. are varied.

  More preferably, the magnetic measurement device further includes a bias magnetic field generation unit that applies a bias magnetic field to the sensor head unit. In this way, the sensitivity of the magnetic measurement device is adjusted by offsetting or summing up the environmental magnetic field applied to the sensor head unit or the magnetic field from the measurement target and the bias magnetic field generated by the bias magnetic field generation unit. be able to. In this way, by using the differential amplifying device that differentially or amplifies the bias magnetic field generation unit and the past calculation result, the detection coil electromotive force generated by a minute external magnetic field fluctuation is reduced to two peak regions. Therefore, the conversion efficiency of the AD converter to which the detection coil electromotive force is input can be increased, and the bit drop can be minimized.

  More preferably, the magnetic body having magnetic anisotropy in the sensor head portion is a solid having at least one of iron garnet, diamond, SiC, or an aggregate of fine solids. In this way, instead of using materials with magnetic anisotropy such as amorphous materials, the magnetic field fluctuations in these micro particles can be detected directly by the detection coil, and a photomultiplier is installed nearby. By doing so, a supplementary signal can be detected. Further, an electromagnetic wave generator having a wide range of wavelengths can be added to modulate the sensor head.

It is the (a) figure and (b) photograph explaining the outline | summary of the sensor part in the magnetic measuring device of this invention. It is a figure explaining the structure of the magnetic measuring device of a present Example. It is a figure explaining the structure of the control circuit in the magnetic measuring device of a present Example. It is a figure which shows the example of the analog signal input into the pulse signal generated from a digital delay pulse generator, and output amplifier. It is a figure explaining the calculation method of the computer in the magnetic measuring device of a present Example. It is a figure explaining the example of an experiment for explaining the principle of operation of the magnetic measuring device of this example. It is a figure explaining the example of an experiment for verifying the magnetic measuring device of a present Example. It is a figure explaining the structure of the control circuit in another Example of this invention, Comprising: It is a figure corresponding to FIG. It is a figure explaining the structure of the sensor part in another Example of this invention, Comprising: It corresponds to FIG. It is a figure explaining the structure of the magnetic measuring device in another Example of this invention, Comprising: It corresponds to FIG. It is a figure explaining the structure of the magnetic measuring device in another Example of this invention, Comprising: It is a figure corresponding to FIG. 2, FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The drawings are simplified as appropriate, and the dimensions and the like in the drawings do not necessarily match the actual dimensions and ratios.

  FIG. 1 is a diagram for explaining the outline of the configuration of the sensor unit 12 in the magnetic measurement apparatus 10 of the present invention. Among these, FIG. 1A is a diagram for explaining the outline of the configuration of the sensor unit 12, and FIG. 1B is a diagram (photograph) for explaining the appearance. As shown in FIG. 1A, the magnetic measuring device 10 of the present invention includes a sensor unit 12 and a circuit unit 14 to be described later. The sensor unit 12 in the present embodiment is configured to have two sensor heads 12a and 12b. As described later, the two sensor heads 12a and 12b can be used in a differential manner. It has become.

As shown in FIG. 1, the sensor section 12 is provided with detection coils 26 and 28 corresponding to one amorphous wire 22 and two sensor heads 12a and 12b. The amorphous wire 22 corresponds to a magnetic material having magnetic anisotropy of the present invention. Electrodes are provided at both ends of the elongated amorphous wire 22, one electrode is grounded, and the other electrode is connected to an electric wire 24, and a drive voltage P _EX is supplied from the circuit unit 14 described later. The This drive voltage P _EX or DP1 described later corresponds to a pulse signal for applying the intermittent direct current of the present invention. Further, one end of each of the detection coils 26 and 28 is installed, and the electric wires 30 and 32 connected to the other end are respectively connected to the circuit unit 14 described later, whereby E is the voltage across the detection coils 26 and 28. _TC1 and _ETC2 can be detected respectively. In addition, the amorphous wire 22 is divided into portions along the detection coils 26 and 28, that is, portions 22a and 22b corresponding to the sensor heads 12a and 12b, and a balance portion 22c that is the other portion. Therefore balance unit 12c does not need the driving voltage P _EX is applied, in order to reduce the electrical loss, a bypass cable 34 for short-circuiting both ends of the balance unit by small electrical resistance cable is provided .

  FIG. 1B is a photograph for explaining the appearance of the sensor unit 12 of this embodiment. As shown in the figure, the sensor unit 12 of this embodiment is mounted on a single substrate 36. In other words, the amorphous wire 22 and the detection coils 26 and 28 are provided on the substrate 36, and a connector 38 for taking out a cable electrically connected to both ends of the amorphous wire 22 is provided at both ends of the detection coils 26 and 28. Connectors 40 and 42 for taking out the cables electrically connected to each are provided.

  FIG. 2 is a diagram for explaining the overall configuration of the magnetic measurement apparatus 10 according to the present embodiment, and particularly for explaining the configuration of the circuit unit 14. As shown in FIG. 2, the circuit unit 14 includes a control circuit 42, a digital delay pulse generator 44, a computer 46, an analog filter 48, a data logger 50, and the like.

  Among these, the control circuit 42 is for controlling the sensor unit 12, that is, for driving or taking out the output. This control circuit may be configured as an electronic circuit designed to perform a desired operation, or may be configured by an FPGA (Field Programmable Gate Array) that allows a designer to program a desired logic function. Good. The control circuit 42 corresponds to the energization unit and the detection unit of the present invention.

  The digital delay pulse generator 44 is a device that can output a pulse waveform having a shape set by an operator. That is, the digital delay pulse generator 44 can output the pulse interval (cycle), width, timing, magnitude, and the like as desired values. In the present embodiment, the digital delay pulse generator 44 can output at least two systems of DP1 and DP2 shown in FIG. The digital delay pulse generator 44 also corresponds to the energization unit of the present invention.

  FIG. 3 is a circuit diagram illustrating an example of the configuration of the control circuit 42. As shown in FIG. 3, the control circuit 42 includes an input amplifier 52, output amplifiers 54 and 56, sample and hold circuits 58 and 60, high-pass filters 62 and 64, low-pass filters 66 and 68, and a differential amplifier 70. ing.

The input amplifier 52 amplifies the pulse signal DP1 input from the digital delay pulse generator 44 with a predetermined amplification factor and outputs the amplified signal from the output port EX. Output _{P EX} from the output port EX is applied to the amorphous wire 22 of the sensor unit 12 via the wire 24. That is, the pulse signal DP1 output from the digital delay pulse generator 44 is a pulse signal that determines a voltage pattern to be applied to the amorphous wire 22.

The output amplifiers 54 and 56 are provided for the detection coils 26 and 28, respectively, and E _TC1 and E _TC2 [V], which are output voltages of the detection coils 26 and 28, are taken in from the input ports S1 and S2, respectively. Amplification is based on the amplification factor. This amplification factor is determined according to specifications such as the resolution of a high-speed AD converter described later.

  The sample and hold circuits 58 and 60 perform hold processing on the analog waveform output from the output amplifiers 54 and 56 in accordance with the pulse signal DP2 supplied from the digital delay pulse generator 44. Specifically, when the pulse signal DP2 becomes a low voltage, it is used as a trigger to hold the value in the analog waveform until it becomes a high voltage again.

FIG. 4 is a diagram showing an example of the pulse signals DP1 and DP2 generated from the digital delay pulse generator 44 and the analog signals of the input ports S1 and S2 input to the output amplifiers 54 and 56. FIG. Represents a theoretical value, and FIG. 4B represents an actual experimental value. As shown in FIG. 4A, the pulse signal DP1 for determining the voltage applied to the amorphous wire 22 is a constant period p of about 1 [μsec] in this embodiment (ie, a frequency of about 1 [MHz]). ), A pulse having a constant width w. The pulse signal DP2 for controlling the sample and hold circuit falls for a moment with a delay of time d from the rise of the pulse signal DP1. Then, the sample hold process is performed by using the rise after the pulse signal DP2 falls as a trigger. This time d is determined in advance by simulation or experiment so that sampling is possible when the output voltages E _TC1 and E _{TC2 of the} detection coils 26 and 28 _reach a peak, for example.

  Further, as shown in FIG. 4B, in this embodiment, the amplitude (pulse magnitude) of both the pulse signals DP1 and DP2 is 5V.

The signals output from the sample and hold circuits 58 and 60 pass through the high-pass filters 62 and 64 and the low-pass filters 66 and 68, so that predetermined frequency components are removed. As shown in FIG. 3, the high-pass filter 62 and the low-pass filter 66 are provided corresponding to the signal output from the sample-and-hold circuit 58, that is, the output E _TC1 of the detection coil 26. The low pass filter 68 is provided corresponding to the signal output from the sample hold circuit 60, that is, the output _ETC2 of the detection coil 28.

The differential amplifier 70 outputs the difference between the output values of the sample and hold circuits 58 and 60 that have passed through the high-pass filters 62 and 64 and the low-pass filters 66 and 68. Thereby, a difference between the output voltages E _TC1 and E _TC2 of the two detection coils 26 and 28 can be obtained.

  The example of the control circuit 42 shown in FIG. 3 describes an example of the control circuit when the outputs of the two sensor heads 12a and 12b in the sensor unit 12 are differentiated. Therefore, when the two sensor heads 12a and 12b are not differentiated, for example, when the outputs of the respective sensor heads 12a and 12b are used singly, the differential amplifier 70 in the control circuit 42 is not required. A terminal is required for each sensor head 12a, 12b.

In the control circuit 42 shown in FIG. 3, the input / output signals are analog signals. However, as shown in FIG. 2, the input signals DP1 and DP2 are converted into digital delay pulse generators 44 as in this embodiment. In the case of the digital signal generated by the control circuit 42, the control circuit 42 can be converted into an analog signal by providing a high-speed DA converter. The same applies to the output signal E _OUT , and it may be converted into a digital signal by a high-speed AD converter at an appropriate stage before being finally processed by the computer 46. In the present embodiment, these high-speed DA / AD converters are not shown.

  Returning to FIG. 2, the computer 46 is a so-called microcomputer having, for example, a CPU, a memory, a ROM, a RAM, etc., and controls the differential of the digital delay pulse generator 44 in accordance with the contents of a program stored in advance. Or, the data obtained from the data logger 50 described later is subjected to predetermined arithmetic processing. The computer 46 corresponds to the calculation unit of the present invention.

  The analog filter 48 includes, for example, a band-pass filter, and extracts only a desired frequency component from the signal output from the control circuit 42.

  The data logger 50 stores the data output from the analog filter 48 according to a predetermined sampling rate. The stored data is output to the computer 46. The data logger 50 corresponds to the storage unit of the present invention.

In the present embodiment, the computer 46 performs an operation for reducing noise on the data obtained from the data logger 50. This calculation will be described with reference to FIG. As shown in FIG. 5A, when a pulse voltage P _EX is applied to the amorphous wire 22, the detection coils 26 and 28 that are close to the portions 22 a and 22 b corresponding to the sensor head of the amorphous wire 22. Voltage fluctuation occurs. A change in the output signals E _TC1 and E _TC2 of the sensor heads 12a and 12b accompanying the generation of one pulse in the pulse signal DP1 is defined as one unit. FIG. 5B shows an example of the output voltage E _coil that accompanies the change of the detection coil a plurality of times when a plurality of pulses are supplied as the pulse signal DP1. The output voltage E _coil of the detection coil corresponds to the output signals E _TC1 and E _TC2 of the detection coils 26 and 28.

The computer 46 integrates the output voltage generated by N pulses with respect to the output voltage E _coil . In this integration, for example, the output voltage E _coil is integrated at every predetermined sampling rate with reference to the rising edge of the pulse signal DP1. The integration interval is appropriately determined from the range of 300 to 1000 [μsec], for example, according to the output waveforms of the detection coils 26 and 28. Integrated value? En _coil of the output voltage _{E coil} is obtained. In such an integrated value, the noise integration is averaged and becomes relatively small with respect to the signal integration, so that the influence of noise on the signal can be reduced. Can be made possible.

The configuration of the magnetic measuring device 10 of the present embodiment is as described above, and the input voltage P _EX to the amorphous wire 22 is given at least once or repeatedly as a pair of a high potential and a low potential. . This is intended to: In other words, an intermittent direct current flows through the amorphous wire 22. Magnetization elements inside the amorphous wire 22 which is a material (having magnetic anisotropy) of the sensor head portion 12 are distributed in the longitudinal direction according to Boltzmann's law by an environmental magnetic field. This internal magnetization is oriented in a certain direction with a current accompanying a high potential. This fixed direction has a vector component in the circumferential direction when the amorphous wire 22 has a linear shape, in other words, a cylindrical shape as in this embodiment. Furthermore, by returning to a low potential, or a small current or no current associated therewith, the environment magnetic field is again controlled. In these two processes, the same proportion of internal magnetization moves in opposite directions. In other words, the internal magnetization in the axial direction depending on the environmental magnetic field is discharged when a high potential is applied, and is absorbed when a low potential side is applied. Since the time constant (reaction / relaxation rate) of the internal magnetization discharge and the absorption reaction is different, the maximum sensitivity can be obtained by suitably selecting the width w (duration) and interval of the direct current applied intermittently. As described above, the magnetic field generated by applying an intermittent direct current to the amorphous wire 22 is generally an actual phenomenon, that is, a magnetic field obtained by applying an alternating current to a coil, that is, The time change of the actually generated magnetic field is also different. The magnetic measuring device 10 of the present embodiment is based on the above principle. In addition, the configuration described later also has an effect of reducing circuit noise.

In the present specification, the pulse signal DP 1 is amplified by the input amplifier 52 and applied as the input voltage P _EX to the amorphous wire 22. Therefore, a concept which corresponds to the level of the input voltage P _EX to voltage high and low and the amorphous wire 22 of the pulse signal DP1. Further, the level of the input voltage P _{EX to} the amorphous wire 22 is a concept that matches the magnitude of the current passed through the amorphous wire 22.

Next, an experiment conducted by the inventor in order to study the operation principle of the magnetic measuring device of the present invention will be described. FIG. 6 is a diagram for explaining such an experiment, and FIG. 6A is a diagram showing a configuration of an apparatus in the experiment. As shown in FIG. 6A, with respect to one sensor head 12a in the sensor unit 12, the longitudinal direction, that is, the direction in which the amorphous wire 22 extends (vertical direction in the plane of FIG. 6A). Conductive wires 74 are arranged at predetermined intervals so as to be orthogonal to each other. Then, in the presence of a certain environmental magnetic field Be, the coil electromotive force _ETC1 of the detection coil 26 (see FIG. 1 and the like) of the sensor head 12a was observed with an oscilloscope in a state where nothing was passed through the conducting wire 74. At this time, the magnitude of the pulse width w (see FIG. 4A) in the pulsed voltage P _EX energized to the amorphous wire 12 is set to a plurality of different values, and the detection coil 26 (see FIG. 1 etc.). ) Coil electromotive force E _TC1 was measured. FIG. 6B shows the relationship of the amplitude of the generated coil electromotive force (induced electromotive force) _ETC1 of the detection coil 26 with respect to the value of the pulse width w obtained in this way. As can be seen from FIG. 6B, as the value of the pulse width w increases, the amplitude of the electromotive force E _TC1 of the detection coil 26 increases, while the value of the pulse width w is 200 to 300 [ nsec], the amplitude of the electromotive force _ETC1 of the detection coil 26 reached the maximum.

Subsequently, a similar experiment was conducted by energizing the AC current I _T of the sinusoidal to the conductor 74. At this time, the amplitude of the sensor output E _OUT that is sample-held by the sample-hold circuit 58 (see FIG. 3) and is continuously output, and the pulse of the pulse-like voltage P _EX that is passed through the amorphous wire 12 The relationship between the width w and the width w is the same as the relationship between the amplitude of the electromotive force E _TC1 of the detection coil 26 and the width w of the pulse when no current is passed through the conducting wire 74 described above. That is, as the value of the pulse width w increases, the amplitude of the sensor output E _OUT increases. On the other hand, when the value of the pulse width w is about 200 to 300 [nsec], the amplitude of the sensor output E _OUT increases. The maximum has been reached.

Considering these results, the circuit of the output of the electromotive force E _TC1 of the detection coil 26 also has a capacitive component, and it is considered that the output wave system is delayed and smoothed. However, as the pulse width w increases, the detection coil Since the magnitude of the amplitude of the electromotive force E _TC1 of 26 is also increased, it can be considered that the direct current component of the excitation pulse is involved in the increase in sensitivity of the magnetic measurement apparatus of the present invention.

  By the way, magnetic detection is performed by applying a high-frequency current to an MI element such as an amorphous wire as in the present invention, and detecting surrounding magnetic fluctuations by utilizing the change in impedance of the MI element due to the skin effect at that time. A so-called MI (Magneto-Impedance) sensor has been proposed.

Since the MI sensor uses the skin effect of the MI element as described above, it is influenced by the high-frequency AC component of the AC current applied to the MI element. That is, the change in the impedance of the MI element depends on the frequency of the alternating current flowing through the MI element. Accordingly, the excitation signal is applied to the wire periodically by applying a current processed in a manner similar to a sine wave to obtain the MI effect (Non-Patent Document 5). On the other hand, in the magnetic measuring device of the present invention, the pulse signal DP1 that is the source of the direct current flowing through the amorphous wire 22 is a pulse wave such as a square pulse. The high frequency component of the wave is not used. That is, as shown in FIG. 6 described above, in the pulse signal DP1 that switches between the low voltage state and the high voltage state, due to the length of the high voltage state switched from the low voltage state, that is, the pulse width w. The magnitude of the electromotive force E _TC1 of the detection coil 26 and the magnitude of the sensor output E _OUT vary. In addition, as shown in FIG. 5 and the like, in the pulse signal DP1, even when the high voltage state is switched to the low voltage state, an electromotive force in the opposite direction to that when the low voltage state is switched to the high voltage state is generated. Although the magnitude of the peak of the electromotive force in the reverse direction is generated in the electromotive force _ETC1 of the detection coil 26, the length of the high voltage state before switching to the low voltage state, that is, the length of the width w of the pulse. It has changed with it. For these reasons, the magnitude of the movement of the internal magnetization of the amorphous wire 22 changes depending on the width w of the pulse in the pulse signal DP1, in other words, the DC component of the voltage applied to the amorphous wire 22, and this is the magnetic measurement device 10. This is considered to determine the detection sensitivity. This is based on the knowledge obtained by the inventors of the present invention. That is, it is considered that the internal magnetization is discharged and absorbed by the pulse ON / OFF.

  In the present invention, the digital delay pulse generator 44 is preferably capable of controlling the pulse width w with high accuracy, specifically, for example, in nanosecond (nsec) units. It is also preferable that the pulse height e, that is, the potential difference between the high potential state and the low potential state can be controlled with high accuracy. Here, “controllable” means, for example, that a stable pulse signal having such a set value can be output. In this way, a magnetic measuring device with high sensitivity and desired sensitivity can be realized.

Furthermore, an experiment conducted by the inventors of the present invention in order to verify the magnetic measurement apparatus of the present embodiment will be described. 7A and 7B are diagrams for explaining the experiment, in which FIG. 7A shows the configuration of the apparatus, and FIG. 7B shows the output voltages E _TC1 , E _TC of the detection coils 26 and 28 as experimental results. shows the time change of _TC2, Fig. 7 (c), the experimental results shown in FIG. 7 (b) the amplitude of the output voltage _{E TC1, E TC2} detection coils 26, 28 and the strength _{M HH} environment field It is a figure explaining a relationship.

As shown in FIG. 7A, a Helmholtz circuit 78 is used in this experiment. The Helmholtz circuit 78 is a well-known circuit, in which two circular coils are arranged in parallel and coaxially, the radius of each coil is equal to the distance between the two coils, and the coil is uniform around the center of the coil. A magnetic field (magnetic field) _MHH can be generated. As shown in FIG. 7A, the sensor unit 12 is arranged so that the sensor heads 12 a and 12 b are positioned near the center of the Helmholtz coil 78. Then, by generating a magnetic field M _HH of a plurality of different intensities to Helmholtz coils 78, was performed to measure the strength of the magnetic field M _HH by the magnetic measuring device 10 of the present embodiment using the sensor portion 12. In this experiment, the conducting wire 74 described with reference to FIG. 6A is not used.

Similarly to the above-described embodiment, the voltage P _EX obtained by amplifying the pulse signal DP1 generated by the digital delay pulse generator 44 by the input amplifier 52 of the control circuit 42 at a predetermined amplification rate is applied to the amorphous wire 22. FIG. 7B shows the time change of the input voltage P _EX and the output voltages E _TC1 and E _TC2 of the detection coils 26 and 28 at this time using a common horizontal time axis. The Helmholtz coil 78 is shown in FIG. 5 shows a case where magnetic fields _MHH having five different strengths from −100 [μT] to 100 [μT] are generated. In this experiment, since the outputs of the detection coils 26 and 28 are theoretically the same, FIGS. 7B and 7C show the one of the detection coils. Is denoted as an output voltage E _TC . (I) to (v) in FIG. 7 (b) are outputs corresponding to the strength of the magnetic field _MHH of the plots marked with triangles shown in (i) to (v) in FIG. 7 (c). Voltage E _TC .

As shown in FIG. 7B, the change in the output voltage E _TC when a stepped pulse having a width (time) w is applied as the input voltage P _EX differs depending on the value of the external magnetic field _MHH. It has become. Specifically, for example, when the magnetic field _MHH is in the vicinity of 100 [μT], when the input voltage P _EX is switched from the low voltage state to the high voltage state, the output voltage E _TC then becomes maximum, and the input voltage P _EX becomes the high voltage. When the state is switched to the low voltage state, the output voltage E _TC thereafter becomes minimum ((i) in FIG. 7B). Further, when the magnetic field _MHH is in the vicinity of −100 [μT], the output voltage E _TC is an output in which the positive and negative are almost opposite to those in the case of 100 [μT], and the input voltage P _EX is changed from the low voltage state to the high voltage state. After switching, the output voltage E _TC then becomes minimum, and when the input voltage P _EX switches from the high voltage state to the low voltage state, the output voltage E _TC thereafter becomes maximum ((v) in FIG. 7B).

Here, considering the example of (i) in FIG. 7B, the maximum in the change in the output voltage E _TC is caused by the direct current component in the high voltage state of the pulse in the input voltage P _EX due to the internal magnetization of the amorphous wire 22. It is thought that this is because the influence of the environmental magnetic field stored in the axial direction is released. Further, the minimum in the change of the output voltage E _TC is that the internal magnetization of the amorphous wire 22 is absorbed by the environmental magnetic field due to the input voltage P _EX returning to the low voltage state, that is, the state where the current flowing through the amorphous wire 22 is small. It is thought to be caused by In other words, the appearance of the maxima and minima of the output voltage E _TC is both those associated with the pulse change in the input voltage P _EX, changes in input voltage P _EX respectively to a high voltage state from a low voltage state, and, The time constants of transitions when the output voltage E _TC changes to the maximum and the minimum are different depending on the change from the high voltage state to the low voltage state, which is the opposite. That is, in the process in which the input voltage P _EX is changed from the low voltage state to the high voltage state and the output voltage E _TC is maximized, the time constant of the output voltage E _TC is several tens [nsec] (several tens of nsec). A steady state is reached in about 200 [nsec]. On the other hand, the process in which the input voltage P _EX is changed from the high voltage state to the low voltage state and the output voltage E _TC is minimized is slower than the process in which the output voltage E _TC is maximized. Therefore, the pulse interval in the input voltage P _EX , that is, the interval until the high voltage state is changed after changing from the high voltage state to the low voltage state is about 2 to 3 [μsec] (interval / period). Otherwise, when the input voltage P _EX becomes a high voltage state again, a sufficiently large response of the output voltage E _TC cannot be obtained. Note that the high voltage state and the low voltage state of the pulse in the input voltage P _EX may be two voltage states having relatively high and low levels, respectively, but preferably the low voltage state is 0 [V]. . In such a case, the current passed through the amorphous wire 22 in the low voltage state is also 0 [A].

The two peaks of the maximum and minimum in the output voltage E _TC reflect the environmental magnetic field _MHH as described above, and each point in the opposite direction. Therefore, by subtracting these two peak values, It is possible to obtain a larger amplitude than using one peak, such as only a maximum value or only a minimum value. Further, by setting the pulse repetition period p (see FIG. 4A) at the input voltage P _EX sufficiently shorter than the hum noise frequency or the like, a filter effect for low frequency circuit noise can be obtained.

The width w of the excitation direct current is usually several hundreds [nsec] level. Therefore, the peak position or region in the opposite direction in the output voltage E _TC of the detection coil usually has only a time shift of several hundreds [nsec] level. On the other hand, since the electric vibration of 50-60 [Hz] depending on circuit noise, for example, AC of the power supply, is extremely long with respect to the time difference of several hundreds [nsec] level of the above-mentioned opposite direction peak, the output voltage E _TC Electric noise in the same direction is given to the two peaks at. Since the amplitude and area of the two peaks change in the opposite sign direction depending on the external magnetic field, the external magnetic field can be measured by subtracting the amplitude and area of the two peaks. At this time, if the sampling time and the integration time for peak calculation are made the same, the low-frequency electrical noise such as a normal power supply is canceled by the difference. This difference calculation improves the accuracy of external magnetic field measurement and simultaneously exhibits a noise filter effect.

As seen in FIG. 7C, the amplitude of the induced electromotive force E _TC generated in the detection coils 26 and 28 changes depending on the external magnetic field _MHH . Since the induced electromotive force E _TC is generated by the movement of the internal magnetization of the amorphous wire 22, the central portion of this graph curve can be approximated as a Boltzmann distribution function of the external magnetic field _MHH intensity. When the energy difference ΔE in which the internal magnetization is oriented in the forward and reverse directions from the central slope of the Boltzmann curve that saturates at about + -50 μT is caused by the spin of electrons, the energy difference is usually proportional to the magnetic flux density B. The magnetic flux density B is expressed by the product of the relative permeability μs, the vacuum permeability μ 0 and the magnetic field strength H. Therefore, the relative permeability of the amorphous material used is estimated to be about 10,000 times that of vacuum. This apparent relative permeability is considered to be a structure in which the magnetic field (magnetic field strength) is strengthened inside the magnetosensitive member, a structure in which the set of electron spins changes simultaneously, or a combination of both. . Therefore, the noise level when it is assumed that a single spin as described in Non-Patent Document 4 is independently affected by a magnetic field is estimated to be about 10 [fT] per 1 cm material. In the case of a structure in which the orientation of the spins changes simultaneously, for example, in the case of a structure in which 10,000 pieces of the orientation change simultaneously, the noise level is 100 [pT]. Therefore, the IPA method for simultaneously controlling many magnetic sensitive members can reduce the noise level by increasing the amount (number, volume) of the magnetic sensitive members.

According to the magnetic measuring apparatus 10 of the present embodiment, the sensor head unit 12 having the amorphous wire 22 having magnetic anisotropy and the generation of the digital delay pulse for generating the stepped pulse signal for energizing the sensor head unit 12 Detector 44 and control circuit 42, detection coils 26 and 28 for measuring the magnetic field generated by sensor head unit 12, and electromotive forces E _TC1 and E _TC2 of detection coils 26 and 28 to sensor head unit 12 by control circuit 42. And a control circuit 42 that detects in synchronization with the energization of the pulse signal DP1 and _PEX are energized by the control circuit 42 to the amorphous wire 22 or the conductive wire 124 provided along the amorphous wire 22 and detected. in the coil 26, due to variations in the magnetic field amorphous wire 22 is generated electromotive force _{E T 1,} E _TC2 is caused by the computer 46, a pulse signal DP1 is changed from the low potential side to the high potential side, and the detection coil 26 based from the high potential side to at least one of the changes to the low potential side , 28, the magnetism is detected based on the change in the electromotive forces E _TC1 and E _TC2 , so that the magnetic measurement is performed with high accuracy and the sensor head unit 12 can be downsized.

Furthermore, according to the embodiments described above, the computer 46 may be stepped pulse signal DP1, P _EX is changed from the low potential side to the high potential side, and the low potential side from the high potential side Following said change Since the magnetism is detected based on the change in the electromotive forces E _TC1 and E _TC2 of the detection coils 26 and 28 based on the change in the pulse signal DP1, P _EX is changed from the low potential side to the high potential side, and captures that has changed subsequent to said change from the high potential side to the low potential side as a pair, the difference or the sum of the amplitude and area of the change of the electromotive force DP1, P _EX detection coils 26 and 28 based thereon It is possible to perform operations such as

Further, according to the above-described embodiment, the pair of the sensor heads 12a and 12b and the pair of the sensor heads 12a and 12b corresponding to the pair of the detection coils 26 and 28 are provided. The amplifier 70 detects the magnetism by subtracting or amplifying the outputs E _TC1 and E _TC2 of the pair of detection coils 26 and 28. Therefore, the amplifier 70 uses a pair of sensor heads in a differential or combined manner. Measurement is possible.

  Further, according to the above-described embodiment, the stepped pulse signal DP1 generated by the digital delay pulse generator 44 can change the time w on the high potential side, so that the magnetic field generated from the sensor head unit 12 can be changed. The size can be appropriately changed to a desired value.

  Further, according to the above-described embodiment, since the amorphous wire 22 is used as the magnetic body having magnetic anisotropy, the current is applied to the amorphous wire 22 or the conductive wire 124 disposed along the amorphous wire 22. The desired effect can be obtained by flowing.

  Further, according to the above-described embodiment, the magnetic body having magnetic anisotropy can be any one of solid, liquid, gas, and vapor, so that the sensor head can be given flexibility in shape. The part 12 can be configured.

  Subsequently, another embodiment of the present invention will be described. In the following description, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 8 is a diagram for explaining the configuration of the control circuit 142 in another embodiment of the present invention, and corresponds to FIG. 3 in the above-described embodiment. In this embodiment, the control circuit 142 shown in FIG. 8 is used in place of the control circuit 42 in the above-described embodiment.

The control circuit 142 of the present embodiment is different in configuration from the control circuit 42 of the above-described embodiment in the following points. That is, the differential amplifier 70 in the control circuit 42 of the above-described embodiment amplifies the difference between the outputs E _TC1 and E _TC2 from the two sensor heads 12a and 12b to a predetermined amplification factor (200 times in the example of FIG. 3). Was. On the other hand, the control circuit 142 of this embodiment amplifies the difference between the output E _TC1 of one sensor head 12a and the past output E ′ _TC1 of the sensor head 12a. This past output E ′ _TC1 is stored in the data logger 50, for example, and is stored together with the time change of the pulse signal DP1 that is the source of the voltage P _EX applied to the amorphous wire 22, for example. When the voltage P _EX is actually applied to the amorphous wire 22, the change in the voltage P _EX , specifically, for example, the rise from the low voltage state to the high voltage state of the input voltage P _EX , In synchronization with the time change of the past pulse signal DP1 stored in the logger 50, the output voltage _E′TC1 stored in accordance with the time change of the past pulse signal DP1 is sequentially output and supplied to the differential amplifier 70. .

Specifically, this aspect is effective in the following cases. That is, when the environmental magnetic field is constant regardless of the passage of time, measurement is performed by the magnetic measurement device 10 of the present embodiment with a time difference between when the measurement target is present and when there is no measurement object, and detection of the sensor head 12a in both cases. A difference from the outputs E _TC1 and E ′ _TC1 of the coil 26 can be obtained. Thereby, the influence of the environmental magnetic field can be removed or reduced from the output voltage of the detection coil 26, and the resolution can be improved with the same limited hardware. According to the magnetic measuring device 10 of the present embodiment, the output of one sensor at different points in time can be differentiated by the differential amplifier 70, so that only one sensor head 12a is required and the configuration is simple. Can be.

According to the above-described embodiment, the magnetic measurement device 10 includes the data logger 50 that stores past calculation results, and the control circuit 42 and the computer 46 include the current calculation results and the past stored in the data logger 50. Since magnetism can be detected by subtracting or amplifying the calculation result, even when there is only one sensor head 12a, the sensor output E _TC1 obtained for a temporally different environment is differentially or summed. It is possible to perform operations such as

  FIG. 9 is a diagram for explaining still another embodiment of the magnetic measurement device 10 of the present invention, and is a diagram for explaining the configuration of the sensor unit 112. FIG. 9 corresponds to FIG. 1 of the above-described embodiment.

  FIG. 9A is a diagram for explaining the outline of the configuration of the sensor unit 112 of the present embodiment, and FIG. 9B is a diagram showing the circuit configuration more simply. The sensor unit 112 of the present embodiment is different from the sensor unit 12 of the above-described embodiment in the following points. That is, (i) the amorphous wire 22 is disposed inside the detection coil 26, and (ii) a conductive wire 124 is provided along the amorphous wire 22. The difference is that it is not electrically connected.

A square-wave voltage P _EX output from the output EX of the control circuit 42 is applied to the conducting wire 124. Here, as shown in FIG. 9, since the conducting wire 124 is disposed along the longitudinal direction of the elongated amorphous wire 22, when the voltage P _EX is applied to the conducting wire 124 and current flows, Similar to the embodiment, the internal magnetization of the amorphous wire 22 changes due to the direct current component of the current. Further, the value of the current flowing through the conducting wire 124 is set to such a magnitude that the internal magnetization of the amorphous wire 22 can be aligned in the matching direction.

  In this embodiment, the detection coil 26 is a cylindrical longitudinal solenoid coil, and an amorphous wire 22 and a conductive wire 124 are disposed in a hollow portion inside the cylinder. Thereby, the change of the internal magnetization of the amorphous wire 22 can be grasped as the change of the electromotive force of the detection coil 26.

  Note that (i) the amorphous wire 22 is disposed inside the detection coil 26, and (ii) the conductive wire 124 along the amorphous wire 22, which is a difference from the sensor unit 12 in the above-described embodiment. The conductive wire 124 may be configured to be different from the sensor unit 12 only in that the conductive wire 124 is not electrically connected to the amorphous wire 22.

  In FIG. 9, only one sensor head 12a has been described as the sensor unit 12 for the long amorphous wire 22 for the sake of simplicity. However, like the sensor unit 12 of FIG. A pair (two) of sensor heads 12 a and 12 b can be provided for the amorphous wire 22.

  In the above-described embodiment, the detection coil 26 is provided so as to surround the sensor head unit 12 and the detection target 90 inside the detection coil 26, so that the apparatus can be downsized and the degree of design freedom can be improved. .

  FIG. 10 is a diagram for explaining the configuration of still another embodiment of the magnetic measurement apparatus of the present invention, and corresponds to FIG. 2, FIG. 3, etc. of the above-described embodiment. In the magnetic measurement device 110 of this embodiment, the magnetic measurement device 10 of the above-described embodiment shown in FIGS. 2 and 3 further includes an oscillator 82 and a coil 84 which will be described later.

  The oscillator 82 in FIG. 10 is connected to a coil 84, and the coil 84 is disposed so that a magnetic field generated from the coil 84 can be applied to the measurement object 90 of the magnetic measurement device 10. A coil 84 current is supplied from the oscillator 82, and a magnetic field that vibrates at a predetermined frequency can be generated from the coil 84. Here, in this embodiment, the oscillating magnetic field generated from the coil 84 has a frequency at which the measurement object 90 can resonate. The oscillator 82 and the coil 84 correspond to the oscillating magnetic field generator of the present invention.

In addition, in the case where the outputs E _TC1 and E _TC2 of the pair of sensor heads 12a and 12b are made differential in this embodiment and the above-described embodiments, either one of the pair of sensor heads 12a and 12b, FIG. In the example, the sensor unit 12 can be disposed so that the measurement target 90 is close to the sensor head 12a. In this way, the environmental magnetic field and the magnetic field from the measurement object 90 are applied to one sensor head 12a, while only the environmental magnetic field is applied to the other sensor head 12b. The output voltage outputs E _TC1 and E _{TC2 of} 28 can be differentiated to eliminate or reduce the influence of the environmental magnetic field, and the output voltage fluctuation range becomes smaller, so that the same hardware is used more. The resolution can be improved.

In this embodiment, the digital delay pulse generator 44 drives the pulse signal DP1 and the sample hold circuits 58 and 60, which are the sources of the drive voltage _PEX supplied to the amorphous wire 22, in the same manner as in the previous embodiment. In addition to two channels 1Ch and 2Ch for generating a reference pulse signal DP2 for generating, a channel 3Ch for generating a trigger signal for controlling the operation of the oscillator 82 is provided. It has 3 channel output ports. The oscillator 82 is connected to the digital delay pulse generator 44 (see FIG. 2), and the oscillator 82 supplies current to the coil 84 based on a control signal from the digital pulse generator 44. The digital pulse generator 44 then applies the excitation voltage P _EX to the amorphous wire 22 and generates a trigger signal for controlling the operation of the oscillator 82 in connection with controlling the sample and hold circuits 58 and 60. . In this way, an oscillating magnetic field can be generated in conjunction with the magnetic measurement by the sensor unit 12.

  FIG. 11 shows the output pattern for each channel of the digital delay pulse generator 44 in the magnetic measuring device 110 of this embodiment, the output from the oscillator 82, and the time change of the oscillating magnetic field applied to the measurement object 90 from the coil 84. It is a time chart for explaining.

As described above, the pulse signal DP1 that is the source of the voltage P _EX for exciting the amorphous wire 22 is generated from 1Ch of the digital delay pulse generator 44. From 3Ch, a trigger signal for starting the oscillator 82 is generated. Here, as shown in FIG. 11, the digital delay pulse generator 44 generates a trigger signal only at time t13 from the time when the pulse signal DP1 rises from the low voltage state to the high voltage state. The oscillator 82 that has received the trigger signal supplies current to the coil 84 for a predetermined time t _OSC . An oscillating magnetic field is generated from the coil 84 during the time t _OSC in which the current flows, and the oscillating magnetic field is attenuated only for a time t _dmp after the current stops. On the other hand, the digital delay pulse generator 44 outputs a pulse signal DP2 as a trigger signal for the sample hold circuits 58 and 60 to perform the sample hold process from 2Ch while the vibration time from the coil 84 is attenuated. .

According to the magnetic measurement apparatus 110 of the present embodiment, the oscillator 82 and the coil 84 that give an oscillating magnetic field to the measurement object 90 are further provided, and the control circuit 42 and the digital delay pulse generator 42 are generated by the oscillator 82 and the coil 84. Since the electromotive force E _TC1 of the detection coil 26 is detected in synchronization with the vibration of the oscillating magnetic field to be generated, a resonance phenomenon or the like can be detected. That is, in a low-intensity static magnetic field environment supplemented by an environmental magnetic field or Helmholtz coil 78 or the like, an oscillating magnetic field corresponding to the resonance frequency of the nucleus / electron in the measurement target 90 is another surrounding second coil. When applied from (for example, the coil 84), the oscillating magnetic field generated by the nuclei / electrons inside the object is detected according to the relaxation time (static magnetic field strength / spin type and its) after applying the oscillating magnetic field. At this time, effective measurement can be performed by synchronizing the measurement (excitation direct current application) interval by the magnetic measurement apparatus of the present embodiment with the resonance frequency of the object.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

  For example, in the above-described embodiment, the example of the sensor head 12 having the two sensors 12a and 12b has been described. However, the present invention is not limited to this, and magnetic measurement can be performed by using one sensor 12a. In such a case, if the configuration as in the second embodiment is not employed, the component portion of the circuit unit 14 that is provided on the assumption that the outputs of the two sensors are operated, that is, the differential amplifier 70 or the like needs to be provided. There is no.

  In the above-described embodiments, the elongated amorphous wire 22 is used as the magnetic body having magnetic anisotropy, but the present invention is not limited to this. For example, as the magnetic body having magnetic anisotropy, a substance having at least one of iron garnet, diamond, and SiC may be used. Further, the shape is not limited to the shape of a long bar, and may be a cylindrical shape or a planar shape, or may be a desired shape such as a planar magnetic body wound in a cylindrical shape, for example. Furthermore, the magnetic body having magnetic anisotropy is not limited to a single solid, but may be an assembly of minute solids, and is not limited to a solid. For example, the magnetic anisotropy contained in a container having a desired shape may be used. It is also possible to use a liquid, gas, or vapor having magnetic anisotropy such as an ionic liquid containing particles. Further, it can be provided as a composite of an amorphous material and the ionic liquid.

In the above-described embodiment, in the circuit unit 14, the sample hold circuits 58 and 60 detect the peaks (peak values) of the amplitudes of the electromotive forces E _TC1 and E _TC2 of the detection coils 26 and 28, respectively. However, at this time, the electromotive forces E _TC1 and E _TC2 of the detection coils 26 and 28 may be input to the sample and hold circuits 58 and 60 after AC coupling by a bandpass filter (not shown).

In the above-described embodiment, a portion of the amorphous wire 22 that does not correspond to the sensor heads 12a and 12b is provided with the bypass cable (conductive wire) 34 for electrically short-circuiting. The entire current P _EX amorphous wire 22 created based on the signal may flow. "

  In the above-described embodiment, the pulse signal DP1 that is the basis of the excitation voltage applied to the amorphous wire 22 has a constant period p. However, the pulse signal DP1 is not limited to this and is an intermittent pulse signal. Also good. That is, the pulse width w is constant, but the generation interval may not be constant. According to the present invention, as described above, the change in electromotive force by the detection coils 26 and 28 due to the rising and falling of the pulse signal DP1 and the subsequent DC current component is detected. This is because the signal DP1 does not need to have a predetermined period.

In the above-described embodiment, the stepped pulse signal DP1 generated by the digital delay pulse generator 44 changes the magnitude of the magnetic field generated from the sensor head unit 12 by changing the time w on the high potential side. However, the present invention is not limited to such a mode. Instead of changing the time w, or in addition, it changes the amplitude of the pulse voltage P _EX to be applied to the amorphous wire 22 and, or, it is also possible to change the size of the magnetic field generated from the sensor head 12. The amplitude of the change in pulse potential P _EX is performed by changing the voltage of the pulse signal DP1 comprising an amplification factor or modified, or the original pulse potential P _EX of the input amplifier 52. This is because the state transition of magnetization occurs depending on the transition speed in the magnetic field strength generated by a certain value of the amplitude of the pulse potential P _EX , and the time w until reaching the steady state is reduced before reaching the sufficient steady state. This is because the induced electromotive force of the detection coil can be adjusted.

10: Magnetic measuring device 12: Sensor head unit 26, 28: Detection coil 42: Control circuit (energization unit / detection unit)
22: Amorphous wire (magnetic material)
50: Data logger (storage unit)
82: Oscillator (oscillating magnetic field generator)
84: Coil (vibrating magnetic field generator)
DP1: _Stepped pulse signals _ETC1 , _ETC2 : electromotive force of detection coil

Claims (9)

A sensor head unit, an energization unit that generates an intermittent direct current for energizing the sensor head unit, a detection coil for measuring a magnetic field generated in the sensor head unit, and an electromotive force of the detection coil A detection unit that detects in synchronization with energization of the sensor head unit by an energization unit,
The sensor head portion includes a magnetic body having magnetic anisotropy,
The energization unit is configured to energize the intermittent direct current to a magnetic body having the magnetic anisotropy or a conductive wire provided along the magnetic body having the magnetic anisotropy,
The detection coil generates an electromotive force due to a variation in a magnetic field generated by the magnetic material having the magnetic anisotropy,
Based on the change in the electromotive force of the detection coil based on at least one of the intermittent DC current changing from the small current side to the large current side and from the large current side to the small current side. A magnetic measurement device comprising a calculation unit for performing detection. The calculation unit generates an electromotive force of the detection coil based on the fact that the intermittent direct current has changed from a small current side to a large current side, and a change from the large current side to the small current side following the change. Detecting magnetism based on changes in
The magnetic measuring device according to claim 1. A pair of the sensor head portions, and a pair of the detection coils corresponding to the pair of sensor head portions,
The arithmetic unit detects magnetism by subtracting or amplifying the outputs of the pair of detection coils,
The magnetic measuring device according to claim 1. A storage unit for storing past calculation results;
The calculation unit performs magnetism detection by subtracting or amplifying a current calculation result and a past calculation result stored in the storage unit,
The magnetic measurement device according to claim 1, wherein the magnetic measurement device is a magnetic measurement device. The detection coil is provided so as to surround the sensor head portion and the detection target inside the detection coil;
The magnetic measurement apparatus according to claim 1, wherein: The intermittent direct current generated by the energization unit can change the time on the large current side,
The magnetic measurement apparatus according to claim 1, wherein: The magnetic body having magnetic anisotropy is an amorphous material;
The magnetic measurement apparatus according to claim 1, wherein: The magnetic body having magnetic anisotropy is in any form of solid, liquid, gas or vapor;
The magnetic measurement apparatus according to claim 1, wherein: It further comprises an oscillating magnetic field generator that applies an oscillating magnetic field to the measurement object,
The detection unit detects an electromotive force of the detection coil in synchronization with vibration of an oscillating magnetic field generated by the oscillating magnetic field generation unit;
The magnetic measurement apparatus according to claim 1, wherein: