JP6094727B2 - Detecting object discriminating device and discriminating method, electric resistivity measuring device and electric resistivity measuring method, component content estimating device and component content estimating method, plate thickness estimating device and plate thickness estimating method - Google Patents

Description

  The present invention relates to a discriminating device and discriminating method for discriminating an object to be detected, an electric resistivity measuring device and an electric resistivity measuring method for measuring the electric resistivity of the object to be detected, and a component content estimation for estimating the component content of the object to be detected. The present invention relates to a device, a component content estimation method, a plate thickness estimation device and a plate thickness estimation method for estimating a plate thickness of an object to be detected.

  There are various methods for analyzing the composition and the like of the detected object, but each has a problem. For example, the chemical method has a problem that the component analysis of the object to be detected is a destructive inspection, and it takes time and equipment. Although X-ray fluorescence analysis is a nondestructive inspection, there is a problem that the surface of the object to be detected needs to be exposed, and the inside cannot be inspected only by analyzing the surface (for example, see Patent Document 1). The method using the thermoelectromotive force (see, for example, Patent Document 2) has a problem that the surface of the object to be detected needs to be exposed and the object to be detected needs to be heated to a certain temperature.

  Moreover, there is an eddy current method as a method for analyzing and discriminating a detected object relatively easily without contact (for example, see Patent Document 3). However, since this method strongly depends on the distance between the object to be detected and the sensor, it must be compared at the same distance. If the shape of the object to be detected is different, an error occurs in the measured value. There was a problem that.

Japanese Patent No. 4755594 JP 2008-170406 A Utility Model Registration No. 3001707

The present invention has been made on the basis of such problems, and the first object is non-contact and non-destructive, not greatly affected by the distance to the object to be detected, and the composition or structure of the object to be detected. It is an object of the present invention to provide a discrimination device or a discrimination method capable of discriminating a difference.
The second object of the present invention is a non-contact and non-destructive electrical resistance measuring device or electrical resistance capable of measuring the electrical resistivity of a detected object without being greatly affected by the distance to the detected object. It is to provide a rate measuring method.
A third object of the present invention is a component content estimation apparatus or a component content estimation method that is non-contact and non-destructive, and that can estimate the component content of the detected object without being greatly affected by the distance to the detected object. Is to provide.
A fourth object of the present invention is a plate thickness estimation device or a plate thickness estimation method that is non-contact and non-destructive and can estimate the plate thickness of the detected object without being greatly affected by the distance to the detected object. Is to provide.

  The discriminating apparatus of the present invention discriminates a difference in composition or structure of an object to be detected, and includes a resonant circuit having a resonant coil and a capacitor, a high-frequency signal generating circuit for supplying a high-frequency signal to the resonant coil, A phase difference detection circuit that detects a phase difference of a signal generated in the coil, an amplitude detection circuit that detects an amplitude of the signal generated in the resonance coil, a phase difference detected by the phase difference detection circuit, and an amplitude detected by the amplitude detection circuit Based on the above, a ratio calculation unit that obtains a ratio of a phase change amount and an amplitude change amount when the detection object is approached from a state where the detection object does not exist in the vicinity of the resonance coil, and a phase change obtained by the ratio calculation unit And a discriminating unit that discriminates a difference in composition or structure of the object to be detected from a ratio between the amount and the amplitude change amount.

  An electrical resistivity measuring device of the present invention measures an electrical resistivity of an object to be detected, and includes a resonant circuit having a resonant coil and a capacitor, a high frequency signal generating circuit for supplying a high frequency signal to the resonant coil, Detected by a phase difference detection circuit that detects a phase difference of a signal generated in the resonance coil, an amplitude detection circuit that detects an amplitude of the signal generated in the resonance coil, and a phase difference detected by the phase difference detection circuit and an amplitude detection circuit Based on the amplitude, a ratio calculation unit that obtains a ratio between a phase change amount and an amplitude change amount when the detection object is brought close to a state where the detection object does not exist in the vicinity of the resonance coil, and a phase obtained by the ratio calculation unit An electrical resistivity calculation unit for obtaining the electrical resistivity of the object to be detected from the ratio between the change amount and the amplitude change amount is provided.

  A component content estimation apparatus of the present invention estimates a component content of an object to be detected, and includes a resonance circuit having a resonance coil and a capacitor, a high-frequency signal generation circuit that supplies a high-frequency signal to the resonance coil, and a resonance coil A phase difference detection circuit for detecting the phase difference of the signal generated in the signal, an amplitude detection circuit for detecting the amplitude of the signal generated in the resonance coil, the phase difference detected by the phase difference detection circuit, and the amplitude detected by the amplitude detection circuit. Based on the ratio calculation unit for obtaining the ratio of the phase change amount and the amplitude change amount when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil, and the phase change amount obtained by the ratio calculation unit And a component content calculation unit for estimating the component content of the detected object from the ratio of the amplitude change amount.

  A plate thickness estimation apparatus according to the present invention estimates a plate thickness of an object to be detected, and includes a resonance circuit having a resonance coil and a capacitor, a high-frequency signal generation circuit that supplies a high-frequency signal to the resonance coil, and a resonance coil A phase difference detection circuit for detecting the phase difference of the signal generated in the signal, an amplitude detection circuit for detecting the amplitude of the signal generated in the resonance coil, the phase difference detected by the phase difference detection circuit, and the amplitude detected by the amplitude detection circuit. Based on the ratio calculation unit for obtaining the ratio of the phase change amount and the amplitude change amount when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil, and the phase change amount obtained by the ratio calculation unit And a plate thickness calculation unit for estimating the plate thickness of the detected object from the ratio of the amplitude change amount.

  The discriminating method of the present invention discriminates the difference in composition or structure of an object to be detected, and uses a resonance circuit having a resonance coil and a capacitor, and detects the object from the state where the object to be detected does not exist in the vicinity of the resonance coil. When the object to be detected is brought closer, the ratio of the phase change amount and the amplitude change amount of the signal generated in the resonance coil is obtained, and the difference in the composition or structure of the object to be detected from the ratio of the obtained phase change amount and amplitude change amount. Is to discriminate.

  The electrical resistivity measurement method of the present invention measures the electrical resistivity of an object to be detected, and uses a resonance circuit having a resonance coil and a capacitor, and the object to be detected does not exist in the vicinity of the resonance coil. When the detected object is approached, the ratio of the phase change amount and the amplitude change amount of the signal generated in the resonance coil is obtained, and the electric resistivity of the detected object is determined from the ratio of the obtained phase change amount and amplitude change amount. Is to be calculated.

  The component content estimation method of the present invention estimates the component content of an object to be detected, and uses a resonance circuit having a resonance coil and a capacitor to detect the object from the state where the object to be detected does not exist in the vicinity of the resonance coil. When the object is brought close, the ratio of the phase change amount and the amplitude change amount of the signal generated in the resonance coil is obtained, and the component content of the detected object is estimated from the ratio of the obtained phase change amount and amplitude change amount It is.

  The plate thickness estimation method of the present invention estimates the plate thickness of an object to be detected, and uses a resonance circuit having a resonance coil and a capacitor to detect the object from a state where the object to be detected does not exist in the vicinity of the resonance coil. When the object is brought close, the ratio of the phase change amount and the amplitude change amount of the signal generated in the resonance coil is obtained, and the plate thickness of the detected object is estimated from the ratio of the obtained phase change amount and amplitude change amount It is.

  In the discriminating apparatus and the discriminating method of the present invention, when the object to be detected is brought close to the resonance coil of the resonance circuit, the state of the resonance coil changes due to the electromagnetic property of the object to be detected, the resonance frequency of the resonance circuit changes, and the resonance There is a phase difference between the signal of the high-frequency signal generator supplied to the circuit and the signal generated in the resonance coil. When the object to be detected is brought close to the resonance coil of the resonance circuit, an eddy current is generated when the object to be detected is an electric conductor, and the amplitude of the signal generated in the resonance coil changes. These phase changes and amplitude changes depend on the distance between the resonance coil and the object to be detected. The degree of this dependence is inversely proportional to the square of the distance between the resonant coil and the object to be detected for both phase change and amplitude change. These phase changes and amplitude changes are affected to the same extent with respect to the distance between the resonant coil and the object to be detected. Therefore, the angle calculated from the ratio between the phase change amount and the amplitude change amount (hereinafter referred to as the discrimination angle) is not greatly affected by the distance between the resonance coil and the detected object, and the magnetic characteristics (ratio) of the detected object. It becomes a value (constant) specific to the object to be detected, which is determined by magnetic permeability, magnetic hysteresis, etc.) and electrical characteristics (electric resistivity, etc.). The feature is that the distance parameter can be deleted from the two information of amplitude change and phase change without measuring the distance between the resonance coil and the object to be detected. A value (discriminant angle) can be calculated.

  In the electrical resistivity measurement device and electrical resistivity measurement method of the present invention, the ratio between the phase change amount and the amplitude change amount is obtained in the same manner as the discrimination device and discrimination method of the present invention. The discrimination angle calculated from the ratio between the phase change amount and the amplitude change amount has a substantially linear relationship with the electrical resistivity when the relative permeability of the detected object is close to 1, so the electrical resistivity is calculated from the discrimination angle. it can.

  In the component content estimation apparatus and the component content estimation method of the present invention, the ratio between the phase change amount and the amplitude change amount is obtained in the same manner as the determination apparatus and determination method of the present invention. The discrimination angle calculated from the ratio between the phase change amount and the amplitude change amount has a substantially linear relationship with the electrical resistivity when the relative permeability of the object to be detected is close to 1, so that the electrical resistivity and the component content If the relationship is known, the component content can be estimated from the discrimination angle.

  In the plate thickness estimation apparatus and the plate thickness estimation method of the present invention, the ratio between the phase change amount and the amplitude change amount is obtained in the same manner as the discrimination device and discrimination method of the present invention. The discrimination angle calculated from the ratio between the phase change amount and the amplitude change amount has a substantially linear relationship with the electrical resistivity when the relative permeability of the detected object is close to 1. The electrical resistivity is a material-specific value that does not depend on the plate thickness. Under the measurement conditions of the present invention, current flows only to a depth that depends on the high-frequency signal that generates eddy current (skin effect). That is, a certain thickness for obtaining the electrical resistivity is required. If the thickness is less than that, the original electrical resistivity of the material cannot be obtained, and apparently the electrical resistivity increases and the discrimination angle decreases. Therefore, when the components and compositions of the detected object are the same and the plate thickness is different, a proportional relationship is generated between the plate thickness of the detected object and the discrimination angle, and the plate thickness can be estimated from the discrimination angle.

  According to the discriminating apparatus and the discriminating method of the present invention, the phase change amount and the amplitude change amount of the signal generated in the resonant coil when the detected object is approached from a state where the detected object does not exist in the vicinity of the resonant coil. Since the ratio is obtained, it is non-contact and non-destructive, and is not greatly affected by the distance between the resonance coil and the object to be detected, and a value (discrimination angle) specific to the composition or tissue of the object to be detected can be obtained. it can. Therefore, the composition or structure of the object to be detected can be easily determined.

  According to the electrical resistivity measuring apparatus and the electrical resistivity measuring method of the present invention, utilizing the fact that the discrimination angle and the electrical resistivity are proportional, the distance between the resonance coil and the object to be detected is non-contact and non-destructive. The electrical resistivity of the object to be detected can be easily measured without being greatly affected.

  According to the component content estimation apparatus and the component content estimation method of the present invention, using the fact that the discrimination angle and the electrical resistivity are proportional, the relationship between the electrical resistivity and the component content is non-contact, non-destructive, and resonant. The component content of the detected object can be easily estimated without being greatly affected by the distance between the coil and the detected object.

  According to the plate thickness estimation apparatus and the plate thickness estimation method of the present invention, utilizing the fact that the discrimination angle and the electrical resistivity are proportional, and the electrical resistivity is a material-specific value independent of the plate thickness, A certain amount of plate thickness is required to generate the eddy current required for discrimination angle measurement, and if it is less than that thickness, there is a correlation between the plate thickness and the discrimination angle. The thickness of the detected object can be easily estimated without being greatly affected by the distance between the detected object and the detected object.

It is a figure showing the structure of the discrimination | determination apparatus which concerns on the 1st Embodiment of this invention. It is a characteristic view showing the relationship between the distance of a resonance coil and a to-be-detected object, a phase difference, and an amplitude. It is a characteristic view showing the relationship between a phase change and an amplitude change. It is a characteristic view explaining a discrimination angle. 2 illustrates a configuration of a resonance coil portion of the resonance circuit illustrated in FIG. 1. 2 shows another configuration of the resonance coil portion of the resonance circuit shown in FIG. 1. 2 illustrates a circuit example of a phase difference detection unit illustrated in FIG. 1. It shows another configuration example of the detection unit. 2 illustrates a configuration example of an amplitude change amount detection unit illustrated in FIG. 1. It is a graph showing the result of a present Example. It is a graph showing the other result of a present Example. It is a characteristic view showing the relationship between a discrimination | determination angle and the electrical resistivity of a to-be-detected object.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(One embodiment)
FIG. 1 shows a configuration of a determination device 1 according to an embodiment of the present invention. This discriminating device 1 discriminates a difference in composition or structure of an object to be detected. For example, a resonance circuit 10 having a resonance coil 11 and a capacitor 12 connected in parallel, and a high-frequency signal to the resonance coil 11. A detection unit 20 that detects the phase difference and amplitude of a signal that is supplied and generated in the resonance coil 11, and a state in which no object to be detected exists in the vicinity of the resonance coil 11 based on the phase difference and amplitude detected by the detection unit 20. A data processing unit 30 is provided for discriminating the difference in composition or structure of the detected object from the ratio of the phase change amount and the amplitude change amount when the detected object is approached. That is, the discriminating apparatus 1 is configured to detect the composition of the detected object or the composition of the detected object from the discrimination angle that is the ratio of the phase change amount and the amplitude change amount of the signal generated in the resonant coil 11 when the detected object is brought close to the resonance coil 11. It distinguishes between organizational differences.

  First, the principle of the discrimination device 1 will be described. When the resonance circuit 10 causes the object to be detected to approach the resonance coil 11, the inductance of the resonance coil 11 changes due to the electromagnetic properties of the object to be detected, and the phase of the signal generated in the resonance coil 11 changes. For example, when the object to be detected is much larger than 1 such as iron or ferrite, when the object to be detected is brought close to the resonance coil 11, the magnetic flux is focused, and the coil is apparently dense. It looks like it is wound around. Therefore, the inductance of the resonance coil 11 is increased, the resonance frequency of the resonance circuit 10 is lowered, and the phase of the signal generated in the resonance coil 11 is compared with the phase when there is no object to be detected in the vicinity of the resonance coil 11. Be late. Conversely, for example, in the case of an object to be detected, such as aluminum or copper, when the object to be detected is brought close to the resonance coil 11, magnetic flux is not converged and the object to be detected is not detected. An eddy current is generated, and the repulsion (reaction) reduces the inductance of the resonance coil 11. This decrease in inductance occurs regardless of the relative permeability. However, if the relative permeability is large, the effect of converging the magnetic flux is large and the effect of reducing the inductance is small, so that the inductance increases. Therefore, when the relative permeability is close to 1, the inductance is decreased, the resonance frequency of the resonance circuit 10 is increased, and the phase advances compared to the phase when the object to be detected does not exist in the vicinity of the resonance coil 11. This phase change is inversely proportional to the square of the distance between the resonant coil 11 and the object to be detected, and the phase change increases as the distance decreases.

  Further, when the detected object is brought close to the resonance coil 11, an eddy current is generated in the detected object. At this time, power is consumed by the electrical resistance of the object to be detected, and the amplitude of the signal generated in the resonance coil 11 changes. In addition, the resonance frequency of the resonance circuit 10 due to the inductance change also changes, and an amplitude change determined by the frequencies of the resonance circuit 10 and the high-frequency signal generator 21 occurs simultaneously. The amplitude at this time is inversely proportional to the square of the distance between the resonant coil 11 and the object to be detected, and the change in amplitude increases as the distance decreases.

FIG. 2 shows the relationship between the distance between the resonance coil 11 and the object to be detected, the phase difference, and the amplitude. FIG. 2 is a result of measuring steel (SS400) as an object to be detected, the horizontal axis is the reciprocal of the square of the distance (unit is mm ⁻² ), and the vertical axis is the output voltage and amplitude of the phase difference detection circuit 23B. This is the output voltage of the detection circuit 22A. As shown in FIG. 2, both the change in phase and the change in amplitude are substantially straight lines, and are inversely proportional to the square of the distance to the object to be detected. The change in phase and the change in amplitude increase as the distance decreases. I understand.

When the phase difference that is the output of the phase difference detection unit 23 is P and the amplitude that is the output of the amplitude detection unit 22 is A, for example, it is expressed by Equation 1 below.
(Formula 1)
P = Kp / d ²
A = Ka / d ²
Here, Kp and Ka are proportional constants, and d is the distance between the resonance coil 11 and the object to be detected.

When the phase difference at the distance d ₀ is P ₀ , the amplitude is A ₀ , the phase difference at the distance d ₁ is P ₁ , and the amplitude is A ₁ , the phase change amount ΔP and the amplitude change amount ΔA are as follows: It is expressed by the formula of
ΔP = P ₁ −P ₀ = Kp / d ₁ ² −Kp / d ₀ ² = Kp (1 / d ₁ ² −1 / d ₀ ² )
ΔA = A ₁ −A ₀ = Ka / d ₁ ² −Ka / d ₀ ² = Ka (1 / d ₁ ² −1 / d ₀ ² )
At this time, ΔA / ΔP, which is a ratio between the phase change amount ΔP and the amplitude change amount ΔA, is expressed by Equation 2 below.
(Formula 2)
ΔA / ΔP = {Ka (1 / d ₁ ² −1 / d ₀ ² )} / {Kp (1 / d ₁ ² −1 / d ₀ ² )}
= Ka / Kp
= Constant These phase change amount and amplitude change amount are affected to the same extent with respect to the distance between the resonance coil 11 and the object to be detected. Therefore, the ratio of the phase change amount and the amplitude change amount becomes a constant with the distance factor eliminated as shown in Equation 2. It is not greatly affected by the distance between the resonance coil and the object to be detected, and is an eigenvalue determined by the magnetic characteristics and electrical characteristics of the object to be detected.
The distance is not the distance between the detection surface 15 and the object to be detected, but actually is a position determined by the physical structure of the resonance coil 11, the ferrite core 14, the covering 17, and the shield 18. Therefore, the distance in Expression 1 is (distance between the detection surface 15 and the object to be detected: measurement distance + constant a). Therefore, Formula 1 is P = Kp / (d + a) ²
A = Ka / (d + a) ²
However, ΔA / ΔP, which is the ratio between the phase change amount ΔP and the amplitude change amount ΔA, is a constant. The distance in the graph of FIG. 2 is created by (distance between the detection surface 15 and the object to be detected: measurement distance + constant).

  For example, the phase difference and the amplitude, which are functions of the distance, are projected on a two-dimensional plane having the phase change on the horizontal axis and the amplitude change on the vertical axis, when the distance between the resonance coil 11 and the object to be detected changes. Both the amplitude change and the amplitude change are scattered on a straight line. From the relationship between the distance between the resonance coil 11 and the detected object shown in FIG. 2, the phase change, and the amplitude change, the horizontal axis represents the phase change and the vertical axis represents the amplitude change. As shown in The slope of this straight line is the ratio between the amount of phase change and the amount of amplitude change, and is a constant and does not depend on the distance between the resonance coil 11 and the object to be detected.

  For example, the composition or structure of the object to be detected can be determined from the inclination (discrimination angle) when the relationship between the phase change and the amplitude change is represented in FIG. Here, the angle of the straight line from the axis is obtained with reference to the axis in the direction in which the amplitude decreases, the direction in which the phase advances is defined as a positive discrimination angle, and the direction in which the phase is delayed is defined as a negative discrimination angle. Hereinafter, the discrimination angle will be described and described as a value calculated from the ratio between the phase change amount and the amplitude change amount. However, since the angle is a non-dimensional quantity, when the ferrite is brought close to the resonance coil 11 and the electrolytic copper is brought close to the resonance coil 11, the angle of the straight line when the ferrite is moved close to the resonance coil 11 but the phase is not changed is not changed. The value calibrated with the straight line angle of +70 degrees is used.

  Next, a specific configuration of the determination device 1 will be described. The resonance circuit 10 has no significant difference in the relationship between the phase change and the amplitude change of the signal generated in the resonance coil 11 in the range of the resonance frequency from 3 KHz to 1 MHz (linearity is maintained). However, the ratio between the phase change amount and the amplitude change amount depends on the resonance frequency characteristic of the resonance circuit 10. Therefore, it is preferable to connect the resistor 13 in parallel to the resonance coil 11 to the resonance circuit 10 so as to adjust the Q value of the resonance circuit 10.

  FIG. 5 shows the configuration of the resonance coil 11 portion of the resonance circuit 10. The resonance coil 11 may be an air core or may have a ferrite core 14. For example, as shown in FIG. 5A, the structure of the air core is suitable for the case where the object to be detected M is detected inside the resonance coil 11, for example, as shown in FIGS. 5B and 5C. As described above, the structure having the ferrite core 14 is suitable for the case where the detection object M is brought close to the detection surface 15 of the resonance coil 11 for detection. 5A and 5B show a cross-sectional structure, and FIG. 5C shows a configuration when the resonance coil 11 shown in FIG.

  The outer periphery of the resonance coil 11 is covered with a plastic body 16 such as an epoxy resin, for example, and a covering body 17 made of ferrite, for example, may be provided on the outer periphery. The plastic body 16 serves to fix the position of the resonance coil 11 and prevent the resonance frequency characteristics of the resonance circuit 10 from changing. By installing the covering member 17, the directivity is improved and it becomes difficult to be affected by other than the detection surface 15, the linearity of the relationship between the phase change and the amplitude change is improved, and the discrimination accuracy can be improved. Since the sensitivity is improved when the ferrite coating 17 is not provided, it is preferable to use them properly according to the purpose.

  When the covering 17 is provided on the outer periphery of the resonance coil 11, for example, it is preferable to provide a shield 18 made of a conductor on the outer periphery. This is because the parasitic capacitance generated in the resonance coil 11 is hardly affected from the outside. The shield 18 is grounded. In addition, when the ferrite core 14 is provided, for example, as shown in FIG. 6, if the ferrite core 14 is protruded from the cover 17 on the detection surface 15, the detection sensitivity can be increased. preferable. However, since the linearity of the relationship between the phase change and the amplitude change is lowered when the ferrite core 14 is protruded, it is preferable that the ferrite core 14 is properly used according to the purpose.

  For example, as illustrated in FIG. 1, the detection unit 20 includes a high-frequency signal generation unit 21 that supplies a high-frequency signal to the resonance circuit 10 via a resistor 24, a phase difference detection unit 23 that detects a phase difference, and an amplitude. And an amplitude detector 22 for detection. The high-frequency signal generation unit 21 includes, for example, a high-frequency signal generation circuit 21A and a buffer amplifier 21B that stabilizes a high-frequency signal output from the high-frequency signal generation circuit 21A. The phase difference detection unit 23 includes, for example, a phase shifter 23A that shifts the phase of the signal output from the high frequency signal generation unit 21, and a phase difference between the signal output from the high frequency signal generation unit 21 and the signal generated in the resonance coil 11. And a phase difference detection circuit 23B for obtaining a phase difference. The amplitude detection unit 22 includes, for example, an amplitude detection circuit 22A that detects the amplitude of a signal generated in the resonance coil 11.

  The high-frequency signal generator 21 is preferably adjusted so as to output a high-frequency signal having a frequency that matches the resonance frequency of the resonance circuit 10 in the state where there is no object to be detected in the vicinity of the resonance coil 11. When the high frequency signal output from the high frequency signal generator 21 is lower than the resonance frequency of the resonance circuit 10, when iron, ferrite, or the like approaches the resonance coil 11, the inductance of the resonance coil 11 increases and the resonance frequency of the resonance circuit 10 becomes high frequency. The amplitude of the signal generated in the resonance coil 11 increases as it approaches the high-frequency signal output from the signal generator 21. Conversely, when the high-frequency signal output from the high-frequency signal generator 21 is lower than the resonance frequency of the resonance circuit 10, when aluminum, copper, or the like approaches the resonance coil 11, the inductance of the resonance coil 11 decreases, and the resonance circuit 10 The resonance frequency moves away from the high-frequency signal output from the high-frequency signal generator 21, and the amplitude of the signal generated in the resonance coil 11 decreases.

  In addition, when the high frequency signal output from the high frequency signal generator 21 is higher than the resonance frequency of the resonance circuit 10, when aluminum, copper, or the like approaches the resonance coil 11, the inductance of the resonance coil 11 is reduced, and the resonance of the resonance circuit 10. The frequency approaches the high frequency signal output from the high frequency signal generator 21, and the amplitude of the signal generated in the resonance coil 11 increases. Conversely, when the high-frequency signal output from the high-frequency signal generator 21 is higher than the resonance frequency of the resonance circuit 10, if iron, ferrite, or the like approaches the resonance coil 11, the inductance of the resonance coil 11 increases, and the resonance circuit 10 The resonance frequency moves away from the high frequency signal output from the high frequency signal generator 21, and the amplitude of the signal generated in the resonance coil 11 decreases.

  Thus, when the high-frequency signal generated by the high-frequency signal generator 21 is different from the resonance frequency of the resonance circuit 10, the relationship between the phase change amount and the amplitude change amount is represented by the graph shown in FIG. Since the original coordinates are represented by different rotated coordinates, correction is required. On the other hand, when the high-frequency signal generated by the high-frequency signal generator 21 matches the resonance frequency of the resonance circuit 10, the amplitude does not increase, so there is no need to correct the phase change and the amplitude change. 4 is represented by the graph shown in FIG. 4, the slope of the straight line (discrimination angle) is within a range of ± 90 degrees.

  When the resonance coil 11 is replaced, the resonance frequency of the resonance circuit 10 is different, so it is preferable to control the frequency of the high-frequency signal generator 21. For example, if the frequency is set such that the amplitude of the signal generated in the resonance coil 11 is maximized when there is no object to be detected in the vicinity of the resonance coil 11, the resonance frequency of the resonance circuit 10 can be matched. The signal output from the high-frequency signal generator 21 is preferably a sine wave, but can also be a rectangular wave. However, in the case of a rectangular wave, the duty ratio is preferably 50%. When the object to be detected is brought close to the resonance coil 11, the state of the resonance circuit 10 changes and the output load of the high frequency signal generation circuit 21A changes. Therefore, a buffer is provided between the high frequency signal generation circuit 21A and the resonance circuit 10. It is preferable to add an amplifier 21B to reduce the load. Note that the frequency at which the amplitude becomes maximum due to the influence of the circuit characteristics of the detection unit 20 may not be the resonance frequency. For example, to calibrate reliably, even if the ferrite body is brought close to the resonance coil 11 and the phase changes, It is preferable to adjust so that the frequency at which the amplitude does not change is output from the high-frequency signal generator 21.

  The phase difference detector 23 detects the phase difference between the points A and B shown in FIG. For the phase difference detection, for example, there is a method of using an exclusive OR gate (XOR gate, for example, PLL IC 4046) and smoothing the output with a resistor and a capacitor to obtain a phase difference output. When the XOR gate is used, a phase difference shifter 23A that shifts the phase of the point A by, for example, about −90 degrees is provided between the high-frequency signal generation unit 21 and the phase difference detection circuit 23B, and continuously even in the vicinity of the phase difference zero. It needs to change. For example, when the phase shifter 23A is not used, an absolute value is output with a phase difference of zero as a boundary, and both the phase difference + and the phase difference − are output of the same polarity, and it is determined whether the phase is advanced or delayed. Because it is impossible, it is invincible. The phase shifter 23A may shift the phase at the point in FIG. 1B and input it to the phase difference detection circuit 23B. At that time, the point of FIG. 1A, which is one input, is directly input to the phase difference detection circuit 23B. FIG. 7 shows a circuit example of the phase difference detection unit 23.

  The high frequency signal generator 21 and the resonance circuit 10 are connected via a resistor 24 therebetween. For example, when the object to be detected is brought close to the resonance coil 11, a phase difference is generated between the signal output from the high frequency signal generator 21 and the signal generated in the resonance coil 11, and the resistance 24 is adjusted. This is because the relationship between the phase change amount and the amplitude change amount can be made constant even if the characteristics of the resonance circuit 10 are slightly different.

  Instead of the resistor 24, for example, as shown in FIG. 8, a signal supply coil 25 connected to the high-frequency signal generator 21 is disposed in the vicinity of the resonant coil 11, so that the high-frequency signal generator 21 and the resonant circuit are arranged. 10 may be connected by a sparse transformer coupling.

  The amplitude detector 22 detects the amplitude of the point B shown in FIG. For example, amplitude detection includes diode detection and a smoothing circuit using a capacitor and a resistor, as shown in FIG. Further, as shown in FIG. 9B, there is an ideal diode method. Since it is not preferable that the amplitude detector 22 affects the resonance circuit 10, it is preferable to increase the input impedance. In addition, a method using a true effective value (RMS) or a method of calculating an amplitude, an effective value, or a power spectrum (FFT) by computer processing after analog-digital conversion of the waveform itself may be used. Good.

  For example, as shown in FIG. 1, the data processing unit 30 is in a state where there is no detected object in the vicinity of the resonance coil 11 based on the phase difference and amplitude detected by the A / D conversion unit 31 and the detection unit 20. From the ratio calculation unit 32 that obtains the ratio of the phase change amount and the amplitude change amount when the detected object is approached from, and the ratio of the phase change amount and the amplitude change amount obtained by the ratio calculation unit 32, the detected object A discriminating section 33 for discriminating the difference in composition or tissue and a frequency control section 34 for controlling the frequency of the high frequency signal generating section 21.

  For example, the ratio calculation unit 32 takes in the outputs of the phase detection unit 23 and the amplitude detection unit 22 that have been analog-digital converted by the A / D conversion unit 31, and the phase difference in a state where no object to be detected exists in the vicinity of the resonance coil 11. And the difference between the reference value (zero point) and the phase difference and the amplitude value when the detected object is approached is calculated as the phase change amount and the amplitude change amount. Is displayed as a graph, and a discrimination angle that is the inclination, that is, a ratio between the phase change amount and the amplitude change amount is calculated and displayed. The graph is, for example, a straight line with a zero point in the state where the object to be detected does not exist in the vicinity of the resonance coil 11, and the discrimination angle that is an inclination is a specific value corresponding to the composition or structure of the object to be detected. In addition, since the scatter diagram of the phase change and the amplitude change is a straight line, in principle, any reference may be used. For example, instead of using the state in which the object to be detected is not present in the vicinity of the resonance coil 11 as a reference, the time when the signal has increased to some extent may be used as the reference value (zero point).

  In this discrimination device 1, for example, when the object to be detected is brought close to the resonance coil 11, the resonance frequency of the resonance circuit 10 changes due to the electromagnetic properties of the object to be detected, and the phase of the signal generated in the resonance coil 11 changes. To do. Further, an eddy current is generated in the object to be detected, and the phase and amplitude of the signal generated in the resonance coil 11 change. At that time, the phase detector 23 detects the phase difference and the amplitude detector 22 detects the amplitude. Based on the detected phase difference and amplitude, the ratio calculation unit 32 obtains the ratio between the phase change amount and the amplitude change amount when the detected object is approached from the state where the detected object is not present in the vicinity of the resonance coil 11. Determine the discrimination angle. From this discrimination angle, the discriminating unit 33 discriminates the composition or structure of the detected object.

  In addition, although the position which makes a to-be-detected object approach the resonant coil 11 may be one point, for example, it is preferable to gradually approach the resonant coil 11 from a slightly separated position and detect a plurality of points. For example, it is possible to reduce the influence of noise and improve discrimination accuracy by calculating linear regression from the phase change and amplitude change at multiple points and obtaining the ratio of the phase change amount and the amplitude change amount from the regression coefficient. It is.

(Example)
Using the determination device 1 described above, the detected object was gradually approached to the resonance coil 11 to determine the composition or structure of the detected object. The objects to be detected are electrolytic copper, 500 yen coins issued in 1990 (Cu 75 wt%, Ni 25 wt%), 500 yen coins issued in 2007 (Cu 72 wt%, Ni8 wt%, Zn20 wt%), lead, titanium An aluminum alloy (Ti 95% by weight, Al 5% by weight), steel (SS400), aluminum, ferrite, and stainless steel (SUS304) were prepared. In addition, although two prepared 500 yen coins with different issuing years are both copper alloys, they are prepared as examples of detected objects (brass and brass) having different alloy compositions. Stainless steel (SUS304) is prepared in a solution heat-treated state, weakly cold-rolled, and strongly cold-rolled. Prepared as.

  In the present embodiment, the ratio calculation unit 32 graphs the relationship between the phase change amount and the amplitude change amount with the horizontal axis representing the phase change and the vertical axis representing the amplitude change, thereby obtaining the inclination (discrimination angle). At that time, for example, as shown in FIG. 4, the inclination (discriminant angle) is an angle and a phase in which the inclination in the direction in which only the amplitude decreases without changing the phase is 0 degree and the inclination in which the phase advances is positive. The angle was determined with negative delay. In addition, ferrite has a high electrical resistance and can be ignored even if eddy currents are generated, and even when approaching the resonance coil 11, the phase is delayed but the amplitude hardly changes. Therefore, the inclination of the ferrite is set to -90 degrees. Further, in this embodiment, calibration is performed with a value obtained by setting the inclination of electrolytic copper to + 70 °. When the frequency of the high-frequency signal generator 21 matches the resonance frequency of the resonance circuit 10 in the state where nothing exists in the vicinity of the resonance coil 11, the discrimination angle of the detected object is in the range of ± 90 °. It becomes.

  First, steel (SS400) was used for the object to be detected, and the relationship between the distance between the resonance coil 11 and the object to be detected, the phase change, and the amplitude change was examined. As shown in FIG. 2, when the reciprocal of the square of the distance between the resonance coil 11 and the object to be detected is taken on the horizontal axis and the phase difference and amplitude are taken on the vertical axis, both the phase difference and the amplitude are linearly related. . Therefore, it was found that both the phase change and the amplitude change are inversely proportional to the square of the distance between the resonance coil 11 and the object to be detected. This is a result of supporting Equation 1 described above.

  Further, as shown in FIG. 3, it can be seen that a linear relationship is obtained when the horizontal axis represents the phase change and the vertical axis represents the amplitude change. This is a result of supporting Equation 2 described above. Therefore, the discrimination angle, which is the ratio between the phase change amount and the amplitude change amount, is not greatly affected by the distance between the resonance coil and the detected object, and is determined by the magnetic and electrical characteristics of the detected object. It turns out that it becomes a peculiar value (discrimination angle).

  FIG. 10 shows a result obtained from the difference in the type of the object to be detected using the above-described discrimination device 1. As shown in FIG. 10, the relationship between the phase change and the amplitude change of each detected object is represented by a straight line, and has different inclinations (discrimination angles) depending on the detected object. Table 1 shows the average angle and standard deviation of 10 samples of each detected object when the ferrite is calibrated at −90 degrees and the electrolytic copper is calibrated at +70 degrees. Thus, it was found that the inclination (discrimination angle) differs depending on the composition, and the difference in the composition of the detected object can be discriminated.

  FIG. 11 shows the results obtained with SUS304 having the same composition, in a solution heat-treated state, subjected to weak cold rolling, and subjected to strong cold rolling. As a result, the SUS304 solution heat treatment state has a positive slope, the weak cold-rolled one has a nearly zero slope, and the strong cold-rolled one has a negative slope. there were. That is, it was found that even when the composition was the same, different angles were obtained due to changes in the structure due to processing, and the difference in structure could be discriminated.

  As described above, according to the present embodiment, the phase change amount and the amplitude change amount of the signal generated in the resonance coil 11 when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil 11. Since the ratio is determined in a non-contact and non-destructive manner, it is not greatly affected by the distance between the resonance coil 11 and the detected object, and a value (discrimination angle) specific to the composition or tissue of the detected object is determined. be able to. Therefore, the composition or structure of the object to be detected can be easily determined.

(Modification)
In the above-described embodiment, the discrimination device 1 and the discrimination method for discriminating the difference in composition or structure of the object to be detected have been described. However, the present invention relates to an electrical resistivity measurement device that measures the electrical resistivity of the object to be detected, and It can be applied to an electrical resistivity measurement method, a component content estimation device and a component content estimation method for estimating a component content of a detected object, or a plate thickness estimation device and a plate thickness estimation method for estimating a plate thickness of a detected object. it can.

  The electrical resistivity measuring device has the same configuration as that of the discriminating device 1 except that the configuration of the discriminating unit 33 of the discriminating device 1 described in the embodiment is different. The electrical resistivity measuring device includes an electrical resistivity calculator that determines the electrical resistivity from the ratio of the phase change amount and the amplitude change amount determined by the ratio calculator 32 instead of the determination unit 33. This utilizes the fact that when the relative permeability of the object to be detected is close to 1, the relationship between the discrimination angle obtained in the ratio calculation unit 32 and the electrical resistivity of the object to be detected is almost a straight line. FIG. 12 shows the relationship between the discrimination angle obtained in the above embodiment and the electrical resistivity of the detected object. In this electrical resistivity measurement method, for example, in the same manner as in the embodiment, the signal generated in the resonant coil 11 when the detected object is approached from a state in which the detected object is not present in the vicinity of the resonant coil 11. The ratio between the phase change amount and the amplitude change amount is obtained, and the electrical resistivity of the detected object is calculated from the obtained ratio between the phase change amount and the amplitude change amount. Therefore, according to the electrical resistivity measuring apparatus and the electrical resistivity measuring method, the electrical resistivity of the detected object is not contacted and nondestructed and is not greatly affected by the distance between the resonance coil 11 and the detected object. Can be measured.

  The component content estimation apparatus has the same configuration as the determination apparatus 1 except that the configuration of the determination unit 33 of the determination apparatus 1 described in the embodiment is different. The component content estimation apparatus includes a component content estimation unit that estimates the component content from the ratio of the phase change amount and the amplitude change amount obtained by the ratio calculation unit 32 instead of the determination unit 33. The component content estimation unit, for example, examines the relationship between the discrimination angle and the component content in advance, and estimates the component content of the detected object from the discrimination angle based on the relationship. For example, when the relative permeability of the object to be detected is close to 1, the electric resistivity is obtained by utilizing the fact that the relationship between the discrimination angle obtained in the ratio calculation unit 32 and the electric resistivity of the object to be detected is almost a straight line. The component content of the detected object can be estimated from the calculated electrical resistivity based on the known relationship between the component content of the detected object and the electrical resistivity. In this component content estimation method, for example, as in the embodiment, the phase of a signal generated in the resonance coil 11 when the object to be detected is approached from the state where the object to be detected does not exist in the vicinity of the resonance coil 11. The ratio between the change amount and the amplitude change amount is obtained, and the component content of the detected object is estimated from the obtained ratio between the phase change amount and the amplitude change amount. Therefore, according to this component content estimation apparatus and component content estimation method, it is possible to estimate the component content of the detected object without contact and non-destruction and without being greatly affected by the distance between the resonance coil 11 and the detected object. Can do.

  The plate thickness estimation apparatus has the same configuration as the determination apparatus 1 except that the configuration of the determination unit 33 of the determination apparatus 1 described in the embodiment is different. The plate thickness estimation apparatus includes a plate thickness estimation unit that estimates the plate thickness from the ratio of the phase change amount and the amplitude change amount obtained by the ratio calculation unit 32 instead of the determination unit 33. For example, when the relative permeability of the object to be detected is close to 1, the plate thickness estimation unit utilizes the fact that the relationship between the discrimination angle obtained in the ratio calculation unit 32 and the electrical resistivity of the object to be detected is substantially a straight line. In addition, the electrical resistivity is a material-specific value that does not depend on the plate thickness, but a certain amount of plate thickness is required to generate the eddy current required for the discrimination angle measurement. The thickness is estimated from the fact that there is a correlation between the discrimination angle. In this plate thickness estimation method, for example, in the same manner as in the embodiment, the phase of a signal generated in the resonance coil 11 when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil 11. The ratio between the change amount and the amplitude change amount is obtained, and the plate thickness is estimated from the relationship with the plate thickness from the obtained ratio between the phase change amount and the amplitude change amount. Therefore, according to the plate thickness estimation apparatus and the plate thickness estimation method, it is possible to estimate the plate thickness of the detected object in a non-contact and non-destructive manner without being greatly affected by the distance between the resonance coil 11 and the detected object. Can do.

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the configurations of the resonance circuit 10, the detection unit 20, the ratio calculation unit 32, and the like have been specifically described. However, other configurations may be used. For example, although the resonance circuit 10 has been described as a parallel resonance circuit, it may be a series resonance circuit as long as it is a resonance circuit. Further, the resistor 24 for supplying a high frequency signal to the resonance circuit 10 may be replaced with a capacitor.

  It is non-contact and non-destructive and is not greatly affected by distance, and can be used for discrimination of composition or structure, measurement of electrical resistivity, estimation of component content, and estimation of sheet thickness.

DESCRIPTION OF SYMBOLS 1 ... Discriminating device, 10 ... Resonance circuit, 11 ... Resonance coil, 12 ... Capacitor, 13 ... Resistance, 14 ... Ferrite core, 15 ... Detection surface, 16 ... Plastic body, 17 ... Covering body, 18 ... Shielding body, 20 ... Detection unit, 21 ... high frequency signal generation unit, 21A ... high frequency signal generation circuit, 21B ... buffer amplifier, 22 ... amplitude detection unit, 22A ... amplitude detection circuit, 23 ... phase difference detection unit,
23A ... Phase shifter, 21B ... Phase difference detection circuit, 24 ... Resistance, 25 ... Signal supply coil, 30 ... Data processing unit, 31 ... A / D conversion unit, 32 ... Ratio calculation unit, 33 ... Discrimination unit, 34 ... Frequency Control unit

Claims (8)

A discriminating device for discriminating differences in composition or structure of an object to be detected,
A resonant circuit having a resonant coil and a capacitor;
A high-frequency signal generating circuit for supplying a high-frequency signal to the resonant coil;
A phase difference detection circuit for detecting a phase difference of a signal generated in the resonance coil;
An amplitude detection circuit for detecting an amplitude of a signal generated in the resonance coil;
Based on the phase difference detected by the phase difference detection circuit and the amplitude detected by the amplitude detection circuit, the amount of phase change and the amplitude when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil A ratio calculation unit that obtains a ratio of the amount of change as a constant independent of the distance between the resonance coil and the object to be detected ;
A discriminating unit for discriminating a difference in composition or tissue of the detected object from a ratio of the phase change amount and the amplitude change amount independent of the distance between the resonance coil and the detected object obtained by the ratio calculating unit. A discrimination device characterized by the above. An electrical resistivity measuring device for measuring electrical resistivity of an object to be detected,
A resonant circuit having a resonant coil and a capacitor;
A high-frequency signal generating circuit for supplying a high-frequency signal to the resonant coil;
A phase difference detection circuit for detecting a phase difference of a signal generated in the resonance coil;
An amplitude detection circuit for detecting an amplitude of a signal generated in the resonance coil;
Based on the phase difference detected by the phase difference detection circuit and the amplitude detected by the amplitude detection circuit, the amount of phase change and the amplitude when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil A ratio calculation unit that obtains a ratio of the amount of change as a constant independent of the distance between the resonance coil and the object to be detected ;
An electrical resistivity calculator that obtains the electrical resistivity of the object to be detected from the ratio of the phase change amount and the amplitude change amount that does not depend on the distance between the resonance coil and the object to be detected obtained by the ratio calculator; An electrical resistivity measuring device. A component content estimation device for estimating a component content of a detected object,
A resonant circuit having a resonant coil and a capacitor;
A high-frequency signal generating circuit for supplying a high-frequency signal to the resonant coil;
A phase difference detection circuit for detecting a phase difference of a signal generated in the resonance coil;
An amplitude detection circuit for detecting an amplitude of a signal generated in the resonance coil;
Based on the phase difference detected by the phase difference detection circuit and the amplitude detected by the amplitude detection circuit, the amount of phase change and the amplitude when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil A ratio calculation unit that obtains a ratio of the amount of change as a constant independent of the distance between the resonance coil and the object to be detected ;
A component content calculation unit for estimating the component content of the detected object from the ratio of the phase change amount and the amplitude change amount independent of the distance between the resonance coil and the detected object obtained by the ratio calculation unit. A component content estimation apparatus characterized by the above. A thickness estimation device for estimating the thickness of an object to be detected,
A resonant circuit having a resonant coil and a capacitor;
A high-frequency signal generating circuit for supplying a high-frequency signal to the resonant coil;
A phase difference detection circuit for detecting a phase difference of a signal generated in the resonance coil;
An amplitude detection circuit for detecting an amplitude of a signal generated in the resonance coil;
Based on the phase difference detected by the phase difference detection circuit and the amplitude detected by the amplitude detection circuit, the amount of phase change and the amplitude when the detection object is approached from the state where the detection object does not exist in the vicinity of the resonance coil A ratio calculation unit that obtains a ratio of the amount of change as a constant independent of the distance between the resonance coil and the object to be detected ;
A plate thickness calculation unit for estimating the plate thickness of the detected object from the ratio of the phase change amount and the amplitude change amount independent of the distance between the resonance coil and the detected object obtained by the ratio calculation unit. A plate thickness estimation device characterized by the above. A discrimination method for discriminating a difference in composition or structure of an object to be detected,
Using a resonance circuit having a resonance coil and a capacitor, the amount of phase change and amplitude change of a signal generated in the resonance coil when the object to be detected is brought close to the resonance coil from a state where the object to be detected does not exist Is determined as a constant that does not depend on the distance between the resonance coil and the object to be detected, and the object to be detected is determined from the ratio of the phase change amount and the amplitude change amount that does not depend on the distance between the resonance coil and the object to be detected. A discrimination method characterized by discriminating a difference in composition or structure of an object. An electrical resistivity measurement method for measuring electrical resistivity of an object to be detected,
Using a resonance circuit having a resonance coil and a capacitor, the amount of phase change and amplitude change of a signal generated in the resonance coil when the object to be detected is brought close to the resonance coil from a state where the object to be detected does not exist Is determined as a constant that does not depend on the distance between the resonance coil and the object to be detected, and the object to be detected is determined from the ratio of the phase change amount and the amplitude change amount that does not depend on the distance between the resonance coil and the object to be detected. An electrical resistivity measurement method, comprising calculating an electrical resistivity of an object. A component content estimation method for estimating a component content of a detected object,
Using a resonance circuit having a resonance coil and a capacitor, the amount of phase change and amplitude change of a signal generated in the resonance coil when the object to be detected is brought close to the resonance coil from a state where the object to be detected does not exist Is determined as a constant that does not depend on the distance between the resonance coil and the object to be detected, and the object to be detected is determined from the ratio of the phase change amount and the amplitude change amount that does not depend on the distance between the resonance coil and the object to be detected. A component content estimation method characterized by estimating a component content of a product. A thickness estimation method for estimating the thickness of a detected object,
Using a resonance circuit having a resonance coil and a capacitor, the amount of phase change and amplitude change of a signal generated in the resonance coil when the object to be detected is brought close to the resonance coil from a state where the object to be detected does not exist Is determined as a constant that does not depend on the distance between the resonance coil and the object to be detected, and the object to be detected is determined from the ratio of the phase change amount and the amplitude change amount that does not depend on the distance between the resonance coil and the object to be detected. A method for estimating a plate thickness, comprising estimating a plate thickness of an object.

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