JP2001041703A - Range finder and thickness meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thickness meter or range finder for a conductive object having a simple and inexpensive structure. SOLUTION: There are provided an AC power supply 40, probe coils 21, 22 disposed in a mutually opposite direction at a separation Go thereof, reference coils 23, 24 generating reference voltage, a voltage detecting means 30, and a computing part 35. And, the computing part 35 is a range finder for measuring distance (g) and a thickness meter 1 for determining thickness (t) from the separation Go and the distances g1, g2 between a determination target object 81 and the probe coils 21, 22 by determining the distances g1, g2 on the basis of variations in difference voltage ΔE/Ea, the difference voltage ΔE between the reference voltage Ea and probe coil voltage Eb relative to the reference voltage Ea. At frequencies below 50 kHz, the material quality or thickness (t) of the object 81 is determined on the basis of a phase difference angle θbetween Eb or ΔE and Ea prior to distance determination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type distance meter and thickness meter which can be manufactured at a low cost with a simple circuit configuration.

[0002]

2. Description of the Related Art As a non-contact type range finder, there is known a range finder which irradiates an object to be determined with ultrasonic waves or light and detects its reflected wave to determine a distance. As a non-contact type thickness gauge, there is also known a thickness gauge which similarly detects a reflected wave or a transmitted wave of an ultrasonic wave to determine its thickness.

[0003]

However, those using ultrasonic waves and light require both a source of ultrasonic waves and light and sensors for detecting these, and are relatively expensive. The present invention seeks to provide a non-contact type distance meter and a thickness meter that can be manufactured at lower cost with respect to a conductive determination target object, and more preferably does not depend on a difference in the material of the determination target object. They want to offer something.

[0004]

A first invention of the present application is a distance meter for measuring a distance between a conductive object and a reference point, comprising a power supply for generating an AC voltage, and an object to be determined connected to the power supply. A probe coil for generating an alternating magnetic field Hi incident on the surface of the probe coil; reference voltage generating means for generating a reference voltage proportional to a current flowing through the probe coil without causing a magnetic field to enter the object to be determined; and a reference point. A determination unit for determining a distance L between the object and the determination target object,
The frequency f of the power supply is a high frequency exceeding 50 kHz, the probe coil is configured such that coordinates P indicating a position with respect to the reference point are known or detectable, and the determination unit determines the reference voltage and the reference voltage. , The total voltage of the probe coil or its reactance voltage component (hereinafter, referred to as
Voltage detecting means for detecting or converting a difference voltage between the reference voltage and the voltage of the probe coil to an appropriate level or the like; and detecting the voltage of the probe coil detected by the voltage detecting means. Voltage E
b or a ratio Eb / Ea, Δ between the detected difference voltage ΔE and the reference voltage Ea detected by the voltage detecting means.
A calculating unit that determines a distance g between the object to be determined and the probe coil based on E / Ea, wherein the calculating unit calculates the position coordinates P of the probe coil and the distance between the object to be determined and the probe coil. The distance meter is characterized in that a distance L between a reference point and an object to be determined is calculated based on a distance g between them.

A distance meter according to the present invention comprises a power supply for generating an AC voltage, a probe coil connected to the power supply for generating an AC magnetic field Hi incident on the surface of the object to be determined, and a magnetic field incident on the object to be determined. A reference voltage generating means for generating a reference voltage which is proportional to a current flowing through the probe coil and a determination unit which determines a distance L between the reference point and the determination target object. In addition, as a supplement, the probe coil and the reference voltage generating means are arranged so as not to magnetically interfere with each other.

[0006] Since a magnetic field Hi is incident on the surface of the object to be determined from the probe coil, and the magnetic field Hi is an alternating magnetic field that changes with time, an eddy current is generated in the object to be determined, which is a conductor by electromagnetic induction. Will flow. Then, a reflected magnetic field is generated so that the eddy current newly cancels the magnetic field Hi of the probe coil, and a voltage (reflected voltage) is applied to the probe coil by the electromagnetic induction of the reflected magnetic field Hr.
Is induced, and the voltage of the probe coil changes (decreases) as compared with the case where there is no object to be determined (see FIG. 18). In FIG. 18, a symbol I2 is an eddy current, a symbol 81 is an object to be determined, and symbols 21 and 291 are a probe coil and its magnetic core.

FIGS. 19 and 20 show these phenomena as equivalent circuits. In the figure, L1
Is a value obtained by idealizing the probe coil to a pure inductance ignoring the resistance value, R1 is an external resistance (it may be considered to include the resistance of the probe coil), and 75
(Secondary side circuit) is an equivalent circuit schematically representing an eddy current circuit flowing through the object to be determined as a series circuit of an inductance L2 and a resistor R2. M is the mutual inductance between the inductances L1 and L2, ε2 (FIG.
0) and I2 are the voltage and eddy current induced in the object to be determined (secondary circuit 75) by the mutual inductance M, and ε1 (FIG. 20) is induced in the primary inductance L1 by the eddy current I2. Reflected voltage (reaction voltage).

[0008] The relationship between the elements shown in FIG. 20 can be expressed by the following equation. E1 = jωL ₁ I ₁ −ε ₁ (1) ε ₂ = jωMI ₁ (2) I ₂ = ε ₂ / (R ₂ + jωL ₂ ) (3) ε ₁ = jωMI ₂ = (ωM ² / L ₁ ) × ｛ R ₂ ² + (ωL ₂ ) ² ｝ ^1/2 × (cos θ + j sin θ) Er (4) where θ = tan ⁻¹ (R ₂ / ωL ₂ ) (5) Er = jωL ₁ I ₁ (6) Then, from the equation (1) and (6), reflected voltage ε1 becomes _{ε 1 = Er-E1 (7} ).

The reflected voltage .epsilon.1 changes depending on the magnitude of the eddy current I2, the eddy shape (expansion and shape, etc.), the gap g (FIG. 18) between the magnetic core and the object to be determined, and the magnetic field Hi
Is not incident on the object to be determined, the voltage drop of the probe coil, that is, the reflected voltage ε1 is theoretically zero.

On the other hand, the reference voltage generating means generates a reference voltage proportional to the current flowing through the probe coil without causing a magnetic field to enter the object to be determined. The voltage detection means constituting the determination unit detects the reference voltage and the voltage of the probe coil (the total voltage of the coil or its reactance voltage component) or the difference voltage between the reference voltage and the voltage of the probe coil, or detects an appropriate level ( Or format)
Convert to That is, the output of the voltage detecting means is a combination of the detection voltage Ea of the reference voltage and the detection voltage Eb of the probe coil, the difference voltage ΔE detected by the reference voltage Ea (direct conversion of the difference voltage or the difference Ea of Ea, Eb). -Eb) or any of the combinations of Ea, Eb, and ΔE. In the example of FIG. 20, Er shown in the equation (6) corresponds to the reference voltage itself, and a value proportional to Er corresponds to a detected value Ea of the reference voltage. E1 in equation (1) corresponds to the reactance voltage component of the probe coil, and the value proportional to E1 corresponds to the detection voltage Eb of the probe coil.
The value proportional to the reflected voltage ε1 in the equation (7) corresponds to the detected value ΔE of the difference voltage.

The magnitude and phase of the reflected voltage .epsilon.1 (and therefore .DELTA.E), and hence the magnitude and phase of the voltage of the probe coil, are determined by the distance g between the probe coil and the object to be determined.
And the magnitude and phase of the eddy current I2 flowing through the object to be determined,
And the shape of the eddy current eddy (circle). The eddy current I2 changes depending on the conductivity and magnetic permeability of the object to be determined (that is, depending on the material of the object to be determined) and the shape (the size of the area and the thickness t in the direction of the magnetic field Hi). Changes only with the area S and the thickness t below a certain value, and changes when the area increases to a certain degree or more, or when the thickness t exceeds the depth limit due to the skin effect of the eddy current. Saturates).

As shown in the above equations (4) and (5), the reflected voltage ε1 is affected by the mutual inductance M and therefore the gap g (FIG. 18), but the phase angle θ is the mutual inductance M and thus the gap g Can be estimated to be determined by the material, shape, size, and frequency f of the magnetic field of the determination target object.

In the present invention, it should be particularly noted that the frequency f of the power supply is set to a high frequency exceeding 50 kHz. The inventors have found that several kHZ to several hundred k
Over the range of HZ, the reflected voltage (therefore Eb, Δ
The relationship between E) and the gap g was tested by changing the frequency,
It has been found that when the frequency exceeds kHZ, almost the same relational expression is obtained without being affected by the material of the object to be determined (see FIG. 5).
That is, as shown in FIGS. 6 to 8 and FIG. 21, which will be described later in detail, when the frequency exceeds 50 kHz, the relationship between the reflection voltage and the gap g becomes a substantially constant carp C regardless of the material of the determination target object. Therefore, it is possible to determine the gap g based on a single determination curve C without considering the difference in the material.

Here, the reflected voltage ε1 used for the determination is
For (Eb, ΔE), it is preferable to use a value ΔE / Ea or Eb / Ea relativized by the reference voltage Ea.
By making the reflected voltage relative to the reference voltage in this way, the effects of short-term and long-term power supply voltage fluctuations are eliminated and the judgment accuracy is improved, compared to the case where the reflected voltage is directly used as the base data for judgment. Because you can. As a result, the calculation unit of the present apparatus calculates the value ΔE / Ea
Alternatively, by using Eb / Ea, it is possible to accurately determine the gap g between the probe coil and the determination target object.

Since the coordinates P indicating the position of the probe coil with respect to the reference point are known or detectable, the distance g between the object to be determined and the probe coil and the coordinates P
Is vector-combined, the calculation unit can calculate the distance L between the reference point and the determination target object. Since the probe coil has a function of a transmitter for transmitting a magnetic signal and a function of a sensor for receiving a reflected signal, the configuration of the apparatus is extremely simple. Also,
Since the frequency f to be used may be a high frequency exceeding 50 kHz, the circuit configuration of the power supply is simple and inexpensive. As a result, the range finder according to the present invention can be an inexpensive non-contact range finder which is not affected by the difference in the material.

The reference voltage generation means has a circuit constant equivalent to that of the probe coil and is connected to the circuit so that the same current flows as the probe coil (ie, the probe coil). Can be realized by a reference coil connected in series (see FIG. 1) or in parallel (see FIG. 16). In order to prevent the voltage of the probe coil from being changed by the reference coil, the reference coil is arranged at a position or in a direction where a magnetic field generated from the reference coil does not enter the object to be determined, or is provided with a magnetic shield. Prevent the magnetic field from entering the object to be determined.

As a result, the reference coil can directly detect the reference voltage of the probe coil corresponding to Er in the above equation (6). Then, by comparing the reference voltage with the voltage of the probe coil,
It is possible to directly grasp the magnitude of the reflected voltage ε1 or the magnitude of the phase angle θ.

The reference voltage detecting means in the voltage detecting means uses a secondary coil magnetically coupled to the reference coil to induce a voltage proportional to the reference voltage. Can be realized. Then, in order to prevent the voltage of the probe coil from being changed by the secondary coil, the secondary coil is arranged at a position or a direction where no magnetic field is incident on the object to be determined, or a magnetic shield is applied to the object to be determined. Make sure that no magnetic field is incident on the object. As a result, a voltage proportional to only the reactance voltage component is induced in the secondary coil by the magnetic flux generated by the reference coil.

On the other hand, the detecting means for detecting the reactance voltage of the probe coil in the voltage detecting means is magnetically coupled to the probe coil and induces a voltage proportional to the reactance voltage component of the probe coil. This can be realized by a secondary coil. That is,
In the secondary coil, a voltage proportional to an induced voltage, that is, a reactance voltage due to a magnetic flux interlinked with the probe coil (a combination of the generated magnetic flux of the probe coil and the reflected magnetic flux from the object to be determined) is induced.

Preferably, the power supply section is a variable frequency power supply capable of changing the frequency f. As described above, the reflected voltage ε1
The magnitude of (ΔE) and its phase also vary with the power supply frequency f. Therefore, by setting the power supply to have a variable frequency, even if the range of the size of the gap g changes, it is possible to set the frequency to a high sensitivity at which the reflected voltage can be sufficiently detected.

Further, it is preferable that the power supply unit is a composite wave voltage source formed by combining a plurality of sinusoidal voltages having different frequencies. And the calculation unit calculates the reference voltage Ea and the voltage Eb of the main coil.
Alternatively, the difference voltage ΔE is sampled at high speed and A / D converted, and the frequency components f1 and f
2,. . . The gap g can be determined by acquiring data every time and using data of a frequency having good sensitivity from the data.

Next, a second invention of the present application is a distance meter for measuring the distance between a conductive object and a reference point, comprising: a power supply for generating an AC voltage; A probe coil for generating an alternating magnetic field Hi incident on the surface of the probe coil; reference voltage generating means for generating a reference voltage proportional to a current flowing through the probe coil without causing a magnetic field to enter the object to be determined; and a reference point. A determination unit for determining a distance L between the object and the determination target object,
The probe coil is configured such that coordinates P indicating a position with respect to the reference point are known or detectable, and the determination unit determines the reference voltage and a total voltage of the probe coil or a reactance voltage component thereof (hereinafter, collectively). A voltage detecting means for detecting or converting a difference voltage between the reference voltage and the voltage of the probe coil to an appropriate level or the like, and determining a distance g between the object to be determined and the probe coil. And an arithmetic unit that performs
The calculation unit is configured to calculate the phase difference angle θ between the reference voltage Ea detected by the voltage detection means and the voltage Eb of the probe coil detected by the voltage detection means or the detected difference voltage ΔE. A first step of determining the material of the object to be determined, and a ratio Eb between the detected voltage Eb of the probe coil or the detected difference voltage ΔE and the reference voltage Ea based on the information on the determined material.
/ Ea, a second step of determining the distance g between the object to be determined and the probe coil based on ΔE / Ea, and the reference point and the object to be determined based on the position coordinates P of the probe coil and the distance g. And a third step of calculating a distance L.

According to the present invention, in the first aspect, a function of judging the material of the object to be judged is added.
A power source having a frequency f equal to or lower than HZ can be used. That is, the arithmetic unit according to the present invention calculates the phase difference angle θ between the detected reference voltage Ea and the detected probe coil voltage Eb or the phase difference between the reference voltage Ea and the detected difference voltage ΔE. A first step of determining the material of the determination target object based on the angle θ. Then, in a second step, based on the information on the determined material, the ratio Eb / Ea, ΔE / E between the detected voltage Eb of the probe coil or the detected difference voltage ΔE and the reference voltage Ea.
The distance g between the determination target object and the probe coil is determined based on a.

As mentioned above, the reflected voltage ε1 (and thus Δ
The magnitude and phase of E), that is, the magnitude and phase of the voltage of the probe coil, vary depending on the magnitude and phase of the eddy current I2 flowing through the object to be determined, the shape of the eddy current (circle), and the like. The eddy current I2 changes depending on the conductivity and the magnetic permeability (that is, the material of the determination target object) and the shape (the size of the area and the thickness t in the direction of the magnetic field Hi) of the determination target object. The magnitude of the eddy current changes with the area and the thickness only in a range where the area S and the thickness t are equal to or smaller than a certain value. If the depth limit is exceeded, the change saturates and the material is the main determinant.

As shown in the above equations (4) and (5), the reflected voltage ε1 is affected by the mutual inductance M and thus the gap g (FIG. 18), but the phase angle θ is independent of the mutual inductance M. Therefore, it can be estimated that the influence of the gap g is small and is determined by the material of the determination target object and the frequency f of the magnetic field. The inventor has found that when the thickness t is greater than a certain value, the phase angle θ or a function (for example, ta) that greatly changes depending on
nθ) was experimentally confirmed to be an excellent index that is less susceptible to fluctuations in the gap g between the determination target object and the probe coil.

For example, as shown in FIG. 18, when a magnetic field Hi is applied to the central portion of the object to be determined and only the material is changed so that the shape of the object to be determined becomes a certain degree or more, the phase angle θ or its phase angle depends on the type of material. The magnitude of tan θ changes.
However, even if the gap g changes within a certain range, the value θ or tan θ hardly changes. Then, the frequency f of the power supply is selected to an appropriate value so that the index including θ such as the above θ or tan θ changes as much as possible according to the given type of the determination target object.

When the material of the object to be determined is determined, the distance g is determined from the measured value of the reflected voltage based on the relational expression (the curve C) between the reflected voltage and the distance g inherent to the material determined by the material. To determine.

In the case where a variable frequency power supply capable of changing the power supply frequency f is provided,
The frequency can be set to be as sensitive as possible to the material determination index including θ.

Further, when the power supply unit is a synthesized wave voltage generation source obtained by synthesizing a plurality of sine wave voltages having different frequencies, processing is performed as described below. That is, the arithmetic unit samples the reference voltage Ea and the voltage Eb of the main coil or the difference voltage ΔE at a high speed, performs A / D conversion, and obtains the frequency components f1, f2,. . . Each time data is acquired, the material of the object to be determined is determined using a frequency that is as sensitive as possible with respect to the material determination index (θ, tan θ, etc.) from the data. Other matters relating to the second invention are the same as those of the first invention.

The third invention of the present application is a thickness gauge for measuring the thickness of a conductive object, comprising: a power source for generating an AC voltage; and a power source connected to the power source, the surface of the object to be determined being viewed from a first direction. A first probe coil for vertically inputting an alternating magnetic field, and an object to be determined which is disposed opposite to the first probe coil at a predetermined distance Go in the first direction and opposite to the first probe coil and connected to the power supply; A second probe coil for applying an alternating magnetic field to the surface of the object perpendicularly from a second direction opposite to the first direction, and a current flowing through the first probe coil without causing a magnetic field to enter the object to be determined. A first reference voltage generating means for generating a proportional first reference voltage; and a second reference voltage generating means for preventing a magnetic field from being incident on the object to be determined and being proportional to a current flowing through the second probe coil.
A second reference voltage generating means for generating a reference voltage; a distance g1 between the first probe coil and the determination target object in a first direction; and a second direction between the second probe coil and the determination target object. To determine the thickness t of the object to be determined in the first and second directions by subtracting the distances g1 and g2 from the distance Go between both coils. And the frequency f of the power supply is 50 kHz.
Z, and the determination unit determines that the first and second reference voltages and the total voltage of the first and second probe coils or their reactance voltage components (hereinafter collectively referred to as the first and second probe coils). Voltage detecting means for detecting the first and second reference voltages and the first and second difference voltages between the first and second reference voltages and the voltages of the first and second probe coils or converting the voltage to an appropriate level or the like. And the voltage E of the first and second probe coils detected by the voltage detecting means.
b or ratios Eb / Ea and ΔE / Ea of the detected first and second difference voltages ΔE and the first and second reference voltages Ea detected by the voltage detecting means, and the objects to be determined, respectively. And a calculation unit for determining distances g1 and g2 between the probe coil and the probe coil.

The thickness gauge according to the present invention includes two sets of the same probe coil and reference voltage generating means as those described in the first and second inventions. Then, the first probe coil and the second probe coil are separated by a certain distance Go.
They are arranged opposite to each other at a distance only. The probe coils, the reference voltage generating means, and the probe coils and the reference voltage generating means of the other probe coil are arranged so as not to magnetically interfere with each other.
And, as in the first invention, the frequency f of the power supply is 50 kHz.
High frequency above Z.

Then, the determination section measures distances g1 and g2 between the object to be determined and the first and second probe coils from the first and second directions opposite to each other, in the same procedure as in the first invention. That is, at a high frequency exceeding 50 kHz, the relationship between the reflection voltage ε1 and the gap g is a substantially constant carp C regardless of the material of the determination target object as described above. Therefore, a single determination curve C can be used without regard to the difference in the material of the determination target object.
, It is possible to determine the gaps g1 and g2 between the respective probe coils and the determination target object. The judgment unit is
Next, as shown in FIG.
From the distance g1 between the first probe coil and the object to be determined
Then, the thickness t of the determination target object is determined by subtracting the distance g2 between the second probe coil and the determination target object.
Other matters are the same as those of the first invention. According to the present invention, it is possible to obtain an inexpensive non-contact thickness gauge which is not affected by the difference in the material.

Next, a fourth invention of the present application is a thickness gauge for measuring the thickness of a conductive object, comprising a power supply for generating an AC voltage, and a first power supply connected to the power supply and provided on a surface of the object to be determined.
A first probe coil for applying an alternating magnetic field perpendicularly to the direction from the first probe coil, and a first probe coil disposed opposite to the first probe coil at a predetermined interval Go in the first direction and connected to the power supply. On the surface of the object to be determined, the first
A second probe coil for applying an alternating magnetic field perpendicularly from a second direction opposite to the first direction, and a first reference voltage which does not cause a magnetic field to enter the object to be determined and is proportional to a current flowing through the first probe coil A first reference voltage generating means for generating a second reference voltage which does not cause a magnetic field to enter the object to be determined and which is proportional to a current flowing through the second probe coil; A distance g1 between the first probe coil and the object to be determined in the first direction and a distance g2 between the second probe coil and the object to be determined in the second direction are determined, and the distance between both coils is determined. A determination unit that determines the thickness t of the determination target object in the first and second directions by subtracting the distances g1 and g2 from Go, and the determination unit refers to the first and second references. Voltage and on First, full voltage or a reactance voltage component of the second probe coils (hereinafter, the first combined, that the voltage of the second probe coil) or the first,
Voltage detecting means for detecting or converting the first and second differential voltages between the second reference voltage and the voltages of the first and second probe coils to an appropriate level, etc .; A calculating unit for determining distances g1 and g2 between the coil and the coil, wherein the calculating unit includes a reference voltage Ea detected by the voltage detecting means and a voltage of the probe coil detected by the voltage detecting means. Eb or a first step of determining the material of the object to be determined based on the phase difference angle θ between the detected difference voltage ΔE and the detected material based on information of the determined material. The probe coil voltage Eb or the detected difference voltage ΔE and the reference voltage Ea
A second step of determining the distances g1 and g2 between the object to be determined and the respective probe coils based on the ratios Eb / Ea and ΔE / Ea of the thickness gauge. is there.

According to the present invention, in the third invention, the same function as that described in the second invention for judging the material of the object to be judged is added so that a power source having a frequency f of 50 kHz or less can be used. is there. That is, the calculation unit according to the present invention calculates the phase difference angle θ or the reference voltage Ea between the detected reference voltage Ea and the detected probe coil voltage Eb.
And determining the material of the object to be determined based on the phase difference angle θ between the detected difference voltage ΔE and the detected difference voltage ΔE. In this material determination step, either the data of the first probe coil or the data of the second probe coil may be used, and the matching of the determination results of both data may be used as the condition for material determination.

When the material of the object to be determined is determined, the distance g is calculated from the measured value of the reflected voltage based on the relational expression (the curve C) between the material-specific distance g determined by the material and the reflected voltage (the curve C). To determine. For others,
This is the same as the third invention.

Next, a fifth invention of the present application relates to a thickness gauge for measuring the thickness of a conductive object made of a predetermined material, comprising: a power supply for generating an AC voltage; A first probe coil for allowing an alternating magnetic field to be perpendicularly incident on the surface of the first probe coil from a first direction; and a first probe coil spaced apart from the first probe coil by a predetermined distance Go in the first direction and oppositely disposed. A second probe coil that is connected to the power supply and that causes an AC magnetic field to be incident on the surface of the object to be determined vertically from a second direction opposite to the first direction; and A first reference voltage generating means for generating a first reference voltage proportional to a current flowing in the first probe coil; and a first reference voltage generating means for preventing a magnetic field from being incident on an object to be determined and being proportional to a current flowing in the second probe coil. A second reference voltage generating means for generating a second reference voltage; a first direction distance g1 between the first probe coil and the determination target object; and a second distance g1 between the second probe coil and the determination target object. A determination unit that determines the thickness g of the object to be determined in the first and second directions by determining the distance g2 in the direction and subtracting the distances g1 and g2 from the distance Go between the coils. , The determination unit includes:
The first and second reference voltages and the total voltage of the first and second probe coils or a reactance voltage component thereof (hereinafter, collectively referred to as voltages of the first and second probe coils).
Alternatively, voltage detecting means for detecting or converting the first and second difference voltages between the first and second reference voltages and the voltages of the first and second probe coils to an appropriate level or the like, and detecting the voltage. Voltage Eb of the probe coil detected by the means
Or the ratio Eb / Ea, ΔE between the detected difference voltage ΔE and the reference voltage Ea detected by the voltage detecting means.
The thickness gauge has a calculation unit for determining distances g1 and g2 between the determination target object and the respective probe coils based on / Ea.

In the present invention, the material of the object to be determined is limited to a predetermined material in advance, so that the step of material determination in the fourth invention is omitted. That is, when the material of the determination target object is known, a simpler thickness gauge of the method of the present invention can be adopted. Others are the same as the fourth invention.

In the thickness gauge according to the third to fifth aspects of the present invention, in order to prevent the first probe coil and the second probe coil from mutually magnetically interfering with each other, as shown in FIG. Although it is conceivable to displace them, as described in claim 6, the first probe coil and the second probe coil are disposed opposite to each other on the same axis, and the first probe coil and the second probe coil are arranged via the object to be determined during the measurement operation. (See FIG. 4).

By opposing the two probe coils in this way, it is possible to reduce the space of the measuring section where the probe coils are arranged and to reduce the size of the apparatus. In addition, since the measurement positions of the gaps g1 and g2 with respect to the object to be determined completely match, even if the object to be determined has a slight bend, the measurement accuracy of the thickness does not decrease. This is because, if the object to be determined has a bend, if the measurement positions of g1 and g2 are shifted, the value of g changes by the amount of the bend, resulting in a thickness error.

The distance meter and the thickness meter according to the present invention are as follows.
The present invention can also be used when the object to be determined is embedded in a normal plastic card. This is because ordinary plastics are non-conductive, and do not affect the measurement accuracy of the present apparatus using magnetism for conductive objects.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 This embodiment relates to a thickness gauge 1 for measuring the thickness of a conductive object. As shown in FIG.
Is connected to the power supply 40 and the first
And a first probe coil 21 for applying an AC magnetic field Hi perpendicularly from the direction shown in FIG. The second probe coil 22 that is connected to vertically enter the AC magnetic field Hi from the second direction opposite to the first direction on the surface of the determination target object 81, and that no magnetic field is incident on the determination target object 81 And the first
A first reference voltage generating means for generating a first reference voltage va proportional to a current flowing through the probe coil 21
The reference coil 23 and a second reference coil 24 serving as a second reference voltage generating means for generating a second reference voltage va proportional to a current flowing through the second probe coil 22 without causing a magnetic field to enter the determination target object 81. As shown in the flowchart of FIG. 3, a distance g1 between the first probe coil 21 and the determination target object 81 in the first direction, and a distance g1 between the second probe coil 22 and the determination target object 81 in the second direction. And a determination unit 3 that determines the thickness t of the determination target object in the first and second directions by measuring the distance g2 of the target object and subtracting the distances g1 and g2 from the distance Go between the two coils. . The frequency f of the power supply 40 is a high frequency exceeding 50 kHz. Further, as shown in FIGS. 1 and 2, the determination unit 3 includes secondary coils 211,
The first and second reference voltages va and the reactance voltage components vb of the first and second probe coils 21 and 22 are detected through the components 21, 21, and 241 to obtain appropriate levels Ea,
Eb, voltage difference ΔE between the detected reference voltage Ea and the detected voltage Eb of the probe coil is calculated to obtain a voltage proportional to the difference voltage Δv between the reference voltage va and the voltage 22 of the probe coil. Means 30 and voltage detecting means 3
0 based on the ratio ΔE / Ea of the difference voltage ΔE detected by 0 to the reference voltage Ea detected by the voltage detecting means 30, and the respective probe coils 21 and
And an operation unit 35 for determining distances g1 and g2 between the control unit 22 and the control unit 22.

As shown in FIG. 4, the first probe coil 21 and the second probe coil 22 are arranged on the same axis Co line so as to face each other, and are indicated by solid lines during the measurement operation. They are magnetically isolated from each other via the determination target object 81 at the position.

The above-mentioned reference voltage generating means is shown in FIG.
As shown in FIG. 2, reference coils 23 and 24 have circuit constants equivalent to the probe coils 21 and 22 and are connected in a circuit so that the same current as the probe coil 21 flows. The detection means for the reference voltage va in the voltage detection means 30 is magnetically coupled to the reference coils 23 and 24 via the magnetic core 291 as shown in FIGS. The secondary coils 231 and 241 for inducing a voltage proportional to the probe coil voltage Vb of the probe coil in the voltage detecting means 30 are magnetically coupled to the probe coils 21 and 22 via the magnetic core 291 to detect the probe. Secondary coils 211 and 221 that induce a voltage proportional to the reactance component of coil voltage vb
It is.

Then, the reference coils 23 and 44 and their 2
The next coils 231 and 241 are arranged at positions where the magnetic field does not enter the determination target object 81. Also,
Needless to say, between the probe coils 21 and 22 and between the reference coils 23 and 24 and one of the probe coils 2
The reference coils 1 and 22 and the other reference coils 24 and 23 are arranged so as not to magnetically interfere with each other. The power supply 50 is a variable frequency power supply that can change the frequency f.

The following is a supplementary explanation for each.
As shown in FIGS. 1 and 2, the probe coil 21 (22)
And each of the magnetic cores 291
Are wound with the secondary coils 211 (221) and 231 (241), and the secondary coils 211 (221) and 231 (2
41) via the respective coils 21 (22), 23
The reactance voltage component in the total voltage of (24) can be obtained. And, as shown in FIG.
An appropriate level of reference voltage E via amplifiers 31 and 32
a, It is converted into the probe coil voltage Eb and the output level is adjusted.

As shown in FIG. 4, the set of the first probe coil 21 and the first reference coil 23 and the set of the second probe coil 22 and the second reference coil 24 are:
They are arranged facing each other on the same axis Co, and are magnetically shielded via the determination target object 81 (however, the reference coil is not shown in FIG. 4). It should be noted that according to a place experimentally determined by the inventor, as shown in FIG.
Is set to w, the diameter of the magnetic core 291 of the coil is set to D, and the gap between the coil and the determination target object 81 is set to g, in order for the determination target object 81 to exhibit an appropriate shielding effect, w> 2
It is preferable to satisfy the relationship of D, g <D / 4.

Then, as shown in FIG. 2, the difference between Ea and Eb is calculated by the subtractor 34, and the difference voltage Δv (= v) between the reference voltage va and the probe coil voltage vb is calculated.
a difference voltage ΔE proportional to a−vb) is obtained. Then, the variable resistance rv of the amplifiers 31 and 32 is adjusted so that the difference voltage ΔE becomes zero when the magnetic field Hi does not enter the determination target object 81.

Then, as shown in FIG.
Converts the reference voltage Ea and the difference voltage ΔE into absolute values | Ea |, | ΔE | via the rectifier circuits 351 and 352, and records the data sequence A / D-converted at a constant sampling period in the data memory 36. . Further, a relative value | ΔE | / | Ea | obtained by dividing each sampled difference voltage | ΔE | by the reference voltage | Ea | is also recorded in the data memory 36. In this way, by resolving | ΔE | with reference voltage | Ea |, data |
Compared with the case where ΔE | is directly used, the influence of short-term and long-term power supply voltage fluctuations can be eliminated, and the determination accuracy can be improved. In the figure, reference numeral 37 denotes a processor for performing data processing, reference numeral 371 denotes a control input / output interface for linking with the position detecting means of the object 81 to be determined, and reference numeral 372 denotes an output interface for outputting the result to a host computer or display. It is.

As described above, the probe coil 21 (2
The magnitude and phase of the reflected voltage ε1 (and therefore ΔE) from the determination target object 81 with respect to 2), and therefore the magnitude and phase of the voltage Eb of the probe coil 21 (22), are different between the probe coil 21 (22) and the determination target object 81. The distance g between
The eddy current I2 flowing through the determination target object 81 (FIGS. 18 to 2)
0) depending on the size and phase, and the shape of the eddy current (circle) of the eddy current I2. The eddy current I2 changes depending on the conductivity and the magnetic permeability of the object to be determined (that is, depending on the material of the object to be determined 81) and the shape (the size of the area S and the thickness t in the magnetic field Hi direction). The size changes with the area and the thickness only in the range where the area S and the thickness t are equal to or less than a certain value, and the area becomes larger than a certain value or the thickness t exceeds the depth limit due to the skin effect of the eddy current. Changes saturate).

As shown in the above equations (4) and (5), the reflected voltage ε1 (ΔE) is equal to the mutual inductance M
Therefore, it can be estimated that it is affected by the gap g (FIG. 19) and is determined by the material, shape and size of the determination target object 81 and the frequency f of the magnetic field Hi.

In this example, what is particularly noteworthy is that the frequency f of the power supply is set to a high frequency exceeding 50 kHz. The inventors have found that several kilohertz to several hundred kilohertz
Over the range of Z, the relationship between the reflected voltage (accordingly, Eb and ΔE) and the gap g was experimented with changing the frequency, and 50 kHz
It has been found that, when the difference exceeds the predetermined value, if the difference in the conductivity of the object to be determined is within a certain range, almost the same curve C is obtained without being affected by the material. That is, as shown in FIG. 21, at a low frequency f, the relationship between the gap g and the reflected voltage becomes a different curve depending on the frequency and the material of the determination target object 81 as shown by a dotted line and a dashed line, but is 50 kHz. When the frequency becomes higher than, the curve approaches a certain curve as shown by a curve C.

More specifically, as shown in FIG. 5, the gap g between the object 81 to be determined and the probe coil is made the same, and the material of the object 81 is copper (Cu), aluminum (Al), When changed to brass (Bs), 5
At 0 kHz or lower, the reflection voltage ΔE / Ea (or Eb, ΔE) greatly differs depending on the material, but when the frequency exceeds 50 kHz, the difference is significantly reduced, and becomes substantially the same at about 100 kHz. FIG. 5 shows an example of a rectangular determination target object 81 in which the size width w1 = 11 mm, the width w2 = 8 mm, the thickness t = 0.3 mm, and the gap g = 0.5.

Therefore, as shown in FIGS. 6 to 8, the relationship between the reflection voltage ΔE / Ea and the gap g is a substantially constant approximate carp regardless of the material of the object 81 to be determined. Therefore, the gap g can be determined based on the single determination curve C that simulates the approximate carp, ignoring the difference in the material of the determination target object 81. 6 to 8 illustrate the determination target object 81.
Is a rectangle, and its size is w1 × w2 (FIG. 18)
11 × 8 mm, thickness t = 0.3 mm, 100 kHz
This is data when the frequency of Z is used.

As described above, the judging section 3 calculates the reflection voltage ΔE / of the first probe coil 21 and the second probe coil 22 as described above.
Ea is measured each time and stored in the data memory 36 of the calculation unit 35. Then, the processor 37 determines gaps g1 and g2 between the determination target object 81 and the probe coils 21 and 22 based on the determination curve C. That is, as shown in FIG. 3, the reflected voltage ΔE / Ea of the first probe coil 21 is read from the data memory 36 in step 601, and the distance g1 is determined by finding the intersection with the above-mentioned determination curve C in step 602. Next, the distance g2 to the second probe coil 22 is determined by the same procedure steps 603 and 604. Then, in step 605,
The distance g1 from the distance Go between the probe coils 21 and 22
And g2 are subtracted to determine the thickness t of the determination target object 81.

In the thickness meter 1 of this embodiment, the probe coils 21 and 22 have the function of a sensor for receiving a reflected signal as well as the function of a magnetic transmitter for transmitting a detection signal. It is simple. Further, since the frequency f to be used may be a high frequency exceeding about 50 kHz, the circuit configuration of the power supply 40 is simple and inexpensive.

In this embodiment, the first probe coil 21
(And the reference coil 23) and the second probe coil 22 (and the reference coil 24) are arranged opposite to each other on the same axis, and are magnetically isolated from each other via the determination target object 81 during the measurement operation ( (Fig. 4). Thus, both coils 2
The probe coil 2
It is possible to reduce the space of the measurement unit including the determination target object 81 and the measurement target object 81 and to reduce the size of the apparatus 1.

Further, since the measurement positions of the gaps g1 and g2 on the object 81 to be judged on the object 81 to be judged completely coincide with each other, even if the object 81 to be judged is slightly bent, the measurement accuracy of the thickness t is reduced. Never do. This is because, when the determination target object 81 has a bend and the measurement positions of g1 and g2 are shifted, the value of g changes by the amount of the bend, resulting in an error in the thickness t. As described above, according to the present example, it is possible to obtain the inexpensive and compact non-contact thickness gauge 1 which is not affected by the difference in the material of the determination target object 81.

Embodiment 2 This embodiment is a range finder 10 for measuring the distance between a conductive object and a reference point, and as shown in FIGS. 9 and 10, a power source 40 for generating an AC voltage. A probe coil 21 connected to the power supply 40 for generating an alternating magnetic field Hi incident on the surface of the determination target object 81; and a reference which does not cause a magnetic field to enter the determination target object 81 and is proportional to the current flowing through the probe coil 21. The reference coil 23 as a reference voltage generating means for generating the voltage va, the lowermost end point of the magnetic core 291 of the probe coil 21 as a reference point and the object 8 to be determined
And a determination unit 3 for determining a distance g from the control unit 1. As shown in FIG. 10, the determination unit 3 detects the reference voltage va and the reactance voltage component vb in the voltage of the probe coil 21 and converts them into appropriate levels Ea and Eb. Difference voltage Δv from voltage vb
Is converted into an appropriate level ΔE, and a calculation unit 35 that determines a distance g between the determination target object 81 and the probe coil 21. The calculation unit 35 determines the material of the determination target object 81 based on the phase difference angle θ between the reference voltage Ea detected by the voltage detection unit 30 and the difference voltage ΔE detected by the voltage detection unit.
The distance g between the determination target object 81 and the probe coil 21 is determined based on the step and the ratio ΔE / Ea of the detected difference voltage ΔE and the reference voltage Ea based on the information on the determined material. And a second step.

The reference coil 23 is a coil equivalent to the probe coil 21 and is arranged so that the magnetic field generated by itself does not enter the object 81 to be determined. When the determination target object 81 is located below the magnetic core 291 forming the reference point and the magnetic flux Hi enters, the reflected voltage ε1 is induced in the probe coil 21 as described above. The probe coil 21 and the reference coil 23 have secondary coils 211 and 221 respectively attached to their magnetic cores 291.
Are wound, and the reactance voltage components of the respective coil voltages are detected via the secondary coils 211 and 221. Further, as shown in FIG. 10, a second reference voltage vc delayed by 90 degrees from the reactance voltage of the reference voltage va is detected from both ends of the external resistor R1. Then, each detection voltage is converted and adjusted into appropriate levels of the reference voltage Ea, the probe voltage Eb, and the second reference voltage Ec via the amplifiers 31 to 33.

The difference between Ea and Eb is calculated by the subtractor 34, and the voltage ΔV proportional to the difference voltage Δv (= va−vb) between the reference voltage va and the probe voltage vb is calculated.
Get E. Then, when the magnetic field Hi is not incident on the determination target object 81, the amplifier 3 is set so that the voltage ΔE becomes zero.
The variable resistances rv of 1, 32 are adjusted.

Then, similarly to the first embodiment, the operation unit 3
5 converts the reference voltage Ea and the difference voltage ΔE into absolute values | Ea | and | ΔE | via the rectifier circuits 351 and 352, and further converts the difference voltage | ΔE | into a relative value | ΔE | / | Ea | Is recorded in the data memory 36. The arithmetic unit 35 synchronizes the difference voltage ΔE with the reference voltage Ea and the second reference voltage Ec via the synchronous rectifier circuits 353 (FIG. 11) and 354, respectively, and | ΔEcosθ | and | ΔEsi
nθ | (θ is the phase difference angle between Ea and ΔE). Then, A / D conversion is performed and the data string is recorded in the data memory 36. Then, the above-mentioned | ΔEsinθ |
By dividing by sθ |, a data sequence of tanθ is calculated and recorded in the data memory 36. The data memory 36 stores reference data indicating the relationship between the material and tan θ at a predetermined frequency f.

FIG. 11 shows an example of the synchronous rectifier circuit 353 for calculating | ΔEcosθ | in an analog manner. In the figure, reference numeral 50 denotes a synchronous rectification circuit main body, and reference numeral 55 denotes a low-pass filter that removes an AC component after synchronous rectification. In the main body 50, reference numeral 53 denotes an inverter for inverting ΔE, and SW1 and SW2
It is a switching element that outputs E or its inverted wave alternately. Reference numeral 51 denotes a waveform shaping circuit that generates a first rectangular wave from the reference voltage Ea, and reference numeral 52 denotes an inverter that generates a second rectangular wave obtained by inverting the first rectangular wave.
The first rectangular wave turns on and off the SW1, and the second rectangular wave turns on and off the SW2. Similarly, from the other synchronous rectification circuit 354, the phase of the circuit 353 is shifted by 90 degrees by replacing Ea with Ec,
| ΔEsinθ |.

Then, as a first step, the computing unit 35 determines the material of the object 81 to be determined based on the measured data of the tan θ. As described above, the reflected voltage ε1
(Accordingly, the magnitude and phase of ΔE), that is, the magnitude and phase of the voltage Eb of the probe coil 21
The eddy current changes depending on the size and phase of the eddy current I2 (FIG. 18) flowing through the eddy current 1 and the shape of the eddy current eddy (circle). And
The eddy current I2 changes depending on the conductivity, the magnetic permeability (that is, the material of the determination target object), the shape, and the size of the determination target object 81. The magnitude of the eddy current changes with the area and the thickness only in a range where the area S and the thickness t are equal to or smaller than a certain value. If the depth limit is exceeded, the change saturates and the material is the main determinant.

As shown in the above equations (4) and (5), the reflected voltage ε1 is affected by the mutual inductance M and thus the gap g (FIG. 18), but the phase angle θ is independent of the mutual inductance M. Therefore, it can be estimated that the influence of the gap g is small and is determined by the material of the determination target object 81 and the frequency f of the magnetic field. The inventor has experimentally confirmed that, when the thickness t and the area are not less than a certain value, the phase angle θ or tan θ is an excellent index that is not easily affected by the gap g as a determination index of the material of the determination target object 81. Confirmed.

For example, as shown in FIG. 18, when the size and thickness of the object 81 to be determined are increased to a certain extent and a magnetic field Hi is applied to the center thereof to change only the material of the object 81 to be determined, the phase angle θ or The magnitude of tan θ changes. However, as the figure shows, the gap g
The value hardly changes even if changes.

Therefore, the material of the object 81 to be determined can be determined based on the reference data indicating the relationship between the material and tan θ at a predetermined frequency stored in the data memory 36 in advance and the measured data of tan θ.

Next, the determination section 3 determines the distance g between the object 81 to be determined and the probe coil 21 based on the material information obtained in the first step. That is, the material and frequency f
Is constant (reflected voltage Δ
E / Ea) and a table showing the relationship between cap g (FIGS.
8) is stored in the data memory 36 for each material, and the reference data is compared with the actually measured value of the reflection voltage ΔE / Ea to determine the distance g of the determination target object 81. As a result, according to the present example, for the same reason as in the first embodiment, it is possible to obtain the distance meter 10 that can measure the distance between the determination target object 81 and the probe coil 21 at low cost and without contact.

Third Embodiment This embodiment is another embodiment in which the same power supply 40 of 50 kHz or less as in the second embodiment and the determination unit 3 shown in FIG. 10 are used in the first embodiment. . Then, as in the second embodiment, the material of the determination target object 81 is determined in the first step, and the distances g1 and g2 are measured based on the material information in the second step. That is, in the first step,
The material of the determination target object 81 is determined from the tan θ data obtained from the first probe coil 21 or the second probe coil 22.

Then, in the second step, based on the obtained material information, the gaps g1 and g are set based on the data between the reflection voltage ΔE / Ea and the gap g relating to the material.
2 is determined. Next, the thickness t of the determination target object 81 is determined by subtracting the distances g1 and g2 from the interval Go. Others are the same as those of the first and second embodiments.

Fourth Embodiment As shown in FIG. 12, this embodiment is different from the second embodiment or the third embodiment in that the power supply section 41 is a combination of a plurality of sinusoidal voltages having different frequencies. Source,
The arithmetic unit 35 calculates the reference voltage Ea and the difference voltage Δ between the reference voltage Ea and the reactance voltage component Eb of the probe coil 21.
E and 1 Msps (Megasample p), for example.
er sec. A) sampled at high speed and A / D
Frequency components f1, f
2,. . . ΔE / Ea and tan which are evaluation data for each
FIG. 12 shows another embodiment of the distance meter 10 and the thickness meter 1 which calculate θ, determine the material, and then determine the gap g. (However, in FIG. Circuit portions of the two probe coils 22 and the second reference coil 24 are not shown).

That is, in this example, as shown in FIG. 12, the reference voltage Ea and the difference voltage ΔE are filtered through A / D converters 361 and 362 after noise is removed through low-pass filters 356 and 357, respectively. The values are converted into values and stored in the data memory 36, respectively. afterwards,
The frequency components f1, f2,... Are calculated by an algorithm such as a discrete Fourier transform method or a fast Fourier transform method. . . The amplitude and phase θ of the reference voltage Ea and the difference voltage ΔE are calculated every time. Then, the tangent of θ (tan θ) is calculated for one or a plurality of frequencies having the highest discrimination ability with respect to the material of the determination target object 81 in the same manner as in the second embodiment, and the material of the determination target object 81 is determined. I do.

Similarly, the relative reflected voltage ΔE / Ea
Is calculated, and the distance g between the determination target object 81 and the probe coil 21 is determined as a second step using a frequency having a high discriminating ability with respect to the distance g based on the material information obtained in the first step. The frequency components f1, f
2,. . . Is, for example, 5 kHz, 10 kHz, 20 k
HZ,. . . , Etc., are set at intervals in geometric progression.

In the case of the thickness gauge 1, the distance g1 between the first probe coil 21 and the object 81 to be determined is determined along with the distance g2 between the second probe coil 22 and the distance between the probe coils 21 and 22. Distances g1 and g2 from Go
In the other example of determining the thickness t of the determination target object 81 by subtracting
Is the same as

Embodiment 5 This embodiment is another embodiment in which the probe coil 21 (22) can be moved in the embodiment 1 to the embodiment 4. As shown in FIG. 13, in the present example, a moving mechanism of the probe coil 21 (22) (not shown) and a detecting means of the moving distance Lo of the probe coil 21 (22) are provided, and the probe coil 21 (22) It can move vertically from position O.

That is, the probe coil 21 (22) can freely move from the reference position O indicated by a broken line to a lower position P indicated by a solid line, and the position P is detected via the detection means.
, That is, the movement distance Lo thereof can be detected. Therefore, the probe coil 21 (22) can be moved to an appropriate position where a reflected voltage ΔE of an appropriate magnitude is generated, and the distance g from the object 81 to be determined can be measured at that position. In the case of the distance meter 10, the moving distance Lo and the distance g are used.
Is added to the reference position O and the object 8 to be determined.
1 can be measured. In addition, thickness gauge 1
In the case of, the distances g1 and g1 are measured at appropriate positions where the distance can be accurately measured, and the thickness t of the determination target object 81 is determined.
Can be measured. Others are the same as those of the first to fourth embodiments.

Embodiment 6 This embodiment is different from the thickness meter 1 of Embodiments 1, 3, 4, and 5 in that the first probe coil 21 (and the first reference coil 23 (not shown) as shown in FIG. ) And the second probe coil 22 (and the second reference coil 24 not shown).
This is another embodiment in which the positions are shifted and not opposed. In this example, the horizontal space tends to be larger by the distance between the probe coils 21 and 22. However, the first probe coil 21 (and the first reference coil 23) and the second probe coil 22 (and Magnetic interference with the second reference coil 24) can be suppressed more reliably. Further, in the case of such a configuration, since the first probe coil 21 and the second probe coil 22 do not have magnetic interference, they can be mutually used as reference coils of the other probe coil.
By eliminating 3, 24, the number of coils can be reduced and the size can be further reduced. Others are the same as in the first, third, fourth and fifth embodiments.

Embodiment 7 This embodiment is different from the range finder 10 of Embodiments 2, 4, and 5 in that
As shown in FIG. 15, another embodiment in which the reference coil 23 is connected in parallel with the probe coil 21 so that a reference voltage va equivalent to the voltage of the probe coil 21 when the determination target object 81 does not exist is obtained. It is a form example. In the present embodiment, it is desirable to increase the external resistance R1 so that the change in current of the probe coil 21 when the determination target object 81 exists and when it does not exist is negligible. Other configurations are the same as those of the second embodiment.
It is the same as 4, 5 and the same effect can be obtained.

Eighth Embodiment This embodiment is a modification of the thickness meter 1 of the first, third, fourth, fifth and sixth embodiments as shown in FIG.
4) is connected in parallel with the probe coil 21 (or 22), and the reference voltage va equivalent to the voltage of the probe coil 21 (or 22) when the determination target object 81 does not exist.
This is another example of the embodiment in which is obtained. In the present embodiment, it is desirable to increase the external resistance R1 so that the change in the current of the probe coils 21 and 22 when the determination target object 81 is present and when it is not present is negligible. Other configurations are the first embodiment,
It is the same as 3, 4, 5, and 6, and the same effect can be obtained.

Embodiment 9 This embodiment is a modification of the thickness meter 1 of Embodiments 1, 3, 4, 5, 6, and 8.
17 shows another embodiment in which a determination target object 81 made of a noble metal is embedded in the surface of a plastic card 8 as shown in FIG. Ordinary plastics are non-conductive and do not affect the thickness measurement accuracy. The plastic card 8 having the noble metal plate embedded therein can be used as an equivalent replacement article such as a prize, and by measuring the thickness t of the noble metal, the magnitude of the replacement value can be determined. In the figure, reference numeral 82 denotes various signs provided on the plastic card 8. About others, embodiment example 1, 3,
Same as 4,5,6,8.

[0080]

As described above, according to the present invention, a thickness gauge or range finder for a conductive object having a simple and inexpensive configuration can be obtained.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a thickness gauge according to a first embodiment.

FIG. 2 is a connection diagram of a thickness gauge according to the first embodiment.

FIG. 3 is a flowchart illustrating a schematic processing procedure of a thickness gauge according to the first embodiment.

FIG. 4 is a conceptual diagram showing an arrangement of a probe coil and a determination target object of the thickness gauge according to the first embodiment.

FIG. 5 is a diagram in which the relationship between the reflected voltage and the frequency when the distance between the object to be determined and the probe coil is fixed is plotted by changing three types of materials.

FIG. 6 is a diagram showing a change in a reflected voltage when the gap g is changed while keeping the frequency constant in the thickness gauge of the first embodiment (when the material of the object to be determined is aluminum).

FIG. 7 is a diagram showing a change in reflected voltage when the gap is changed while keeping the frequency constant in the thickness gauge according to the first embodiment (when the material of the object to be determined is brass);

FIG. 8 is a diagram showing a change in reflected voltage when the gap is changed while keeping the frequency constant in the thickness gauge according to the first embodiment (when the material of the object to be determined is copper);

FIG. 9 is a system configuration diagram of a distance meter according to a second embodiment.

FIG. 10 is a connection diagram of a distance meter according to the second embodiment.

11 is a connection diagram of the synchronous rectifier circuit 353 of FIG.

FIG. 12 is a connection diagram of a distance meter according to a fourth embodiment.

FIG. 13 is a view schematically showing a mode of movement of a probe coil in a distance meter or a thickness meter according to the fifth embodiment.

FIG. 14 is a diagram showing an arrangement of probe coils of a thickness gauge according to Embodiment 6 (reference coils are not shown).

FIG. 15 is a system connection diagram of the distance meter according to the seventh embodiment.

FIG. 16 is a system connection diagram of the thickness gauge according to the eighth embodiment.

FIG. 17 is a perspective view of a plastic card according to Embodiment 9;

FIG. 18 is a conceptual diagram illustrating an electromagnetic phenomenon that occurs when magnetic interference exists between a determination target object and a coil.

FIG. 19 is a circuit diagram illustrating the phenomenon shown in FIG. 18 using a mutual inductance M;

FIG. 20 is a circuit diagram illustrating the phenomenon shown in FIG. 18 using the display of voltage sources ε1 and ε2.

FIG. 21 is a diagram schematically showing a phenomenon of converging to a single curve when the frequency is increased in the diagram showing the relationship between the reflected voltage and the value of the gap.

FIG. 22 is a diagram schematically showing a relationship between distances g1 and g2 and a thickness t in the thickness gauge of the present invention.

[Explanation of symbols]

 1: Thickness gauge 3: Judgment unit 8: Plastic card 10: Distance meter 21, 22: Probe coil 23, 24: Reference coil 30: Voltage detection means 34: Subtractor 35: Operation unit 36: Data memory 37: Processor 40, 41: power supply 31, 32: amplifier 81: object to be determined 291: magnetic core 353, 354: synchronous rectifier circuit 351, 352: rectifier circuit 356, 357: low-pass filter Ea, va: reference voltage Eb, vb: probe coil voltage g1 , G1: distance, gap ΔE: difference voltage between probe coil voltage and reference voltage θ: phase angle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takanori Shunama 4-7-1, Myojin-cho, Hachioji-shi, Tokyo Hachioji ON Bldg. 3F Inside Three Systems Engineering Co., Ltd. (72) Inventor Seito Ekura F-term (reference) 2F063 AA02 AA16 BB02 BC05 CA40 DA01 DD05 EB24 GA08 GA29 GA33 LA06 LA11 LA19 LA23 LA25 LA29

Claims (10)

[Claims] 1. A rangefinder for measuring a distance between a conductive object and a reference point, comprising: a power supply for generating an AC voltage;
A probe coil connected to the power supply for generating an alternating magnetic field Hi incident on the surface of the object to be determined, and a reference that does not cause a magnetic field to be incident on the object to be determined and generates a reference voltage proportional to the current flowing through the probe coil A voltage generating means, and a determination unit for determining a distance L between the reference point and the determination target object. The frequency f of the power source is a high frequency exceeding 50 kHz, and the probe coil is The coordinate P indicating the position with respect to the point is configured to be known or detectable, and the determination unit determines the reference voltage and the total voltage of the probe coil or a reactance voltage component thereof (hereinafter, referred to as a reactance voltage component).
Voltage detecting means for detecting or converting a difference voltage between the reference voltage and the voltage of the probe coil to an appropriate level or the like; and detecting the voltage of the probe coil detected by the voltage detecting means. Voltage E
b or a ratio Eb / Ea, Δ between the detected difference voltage ΔE and the reference voltage Ea detected by the voltage detecting means.
A calculating unit for determining a distance g between the object to be determined and the probe coil based on E / Ea, wherein the calculating unit calculates the position coordinates P of the probe coil and the distance between the object to be determined and the probe coil. A distance meter which calculates a distance L between a reference point and an object to be determined based on a distance g between the distance points. 2. A rangefinder for measuring a distance between a conductive object and a reference point, comprising: a power supply for generating an AC voltage;
A probe coil connected to the power supply for generating an alternating magnetic field Hi incident on the surface of the object to be determined, and a reference that does not cause a magnetic field to be incident on the object to be determined and generates a reference voltage proportional to the current flowing through the probe coil A voltage generator, and a determination unit that determines a distance L between the reference point and the determination target object. The probe coil is configured such that coordinates P indicating a position with respect to the reference point are known or detectable. The determination unit is configured to determine the reference voltage, a total voltage of the probe coil or a reactance voltage component thereof (hereinafter, collectively referred to as a voltage of the probe coil) or a difference voltage between the reference voltage and the voltage of the probe coil. Voltage detecting means for detecting or converting the voltage to an appropriate level, and an arithmetic unit for determining the distance g between the object to be determined and the probe coil. The arithmetic unit has a phase difference between the reference voltage Ea detected by the voltage detecting means and the voltage Eb of the probe coil detected by the voltage detecting means or a detected difference voltage ΔE. A first step of determining the material of the object to be determined based on the angle θ, and based on the determined information on the material, the detected voltage Eb of the probe coil or the detected difference voltage ΔE and the reference voltage Ratio Eb with Ea
/ Ea, a second step of determining the distance g between the object to be determined and the probe coil based on ΔE / Ea, and the reference point and the object to be determined based on the position coordinates P of the probe coil and the distance g. A third step of calculating a distance L. 3. A thickness gauge for measuring the thickness of a conductive object, comprising: a power supply for generating an AC voltage; and an AC magnetic field connected to the power supply and vertically applied from a first direction to a surface of the object to be determined. The first probe coil to be incident and the first probe coil are disposed opposite to each other at a predetermined interval Go in the first direction with respect to the first probe coil, and are connected to the power supply and on the surface of the determination target object. A second probe coil for applying an alternating magnetic field perpendicularly from a second direction opposite to the one direction, and a first reference which does not cause a magnetic field to be incident on the object to be determined and is proportional to a current flowing through the first probe coil. First reference voltage generating means for generating a voltage, and second reference voltage generating means for generating a second reference voltage proportional to a current flowing through the second probe coil without causing a magnetic field to enter the object to be determined Means, a distance g1 in the first direction between the first probe coil and the object to be determined, and the second
The distance g2 in the second direction between the probe coil and the object to be determined is determined, and the distances g1 and g2 are subtracted from the distance Go between the two coils, so that the object in the first and second directions of the object to be determined is determined. A determination unit that determines the thickness t; the frequency f of the power supply is a high frequency exceeding 50 kHz; and the determination unit determines the first and second reference voltages and the first and second reference voltages. The total voltage of the two probe coils or its reactance voltage component (hereinafter collectively referred to as voltages of the first and second probe coils) or between the first and second reference voltages and the voltages of the first and second probe coils. First and second
Voltage detecting means for detecting the difference voltage or converting it to an appropriate level or the like; voltage Eb of the first and second probe coils detected by the voltage detecting means or the first and second difference voltages ΔE detected And the ratio Eb / Ea, Δ of the first and second reference voltages Ea detected by the voltage detecting means.
A thickness gauge comprising: a calculation unit that determines distances g1 and g2 between a determination target object and respective probe coils based on E / Ea. 4. A thickness gauge for measuring the thickness of a conductive object, comprising: a power supply for generating an AC voltage; and an AC magnetic field connected to the power supply and perpendicular to a surface of the object to be determined from a first direction. The first probe coil to be incident and the first probe coil are disposed opposite to each other at a predetermined interval Go in the first direction with respect to the first probe coil, and are connected to the power supply and on the surface of the determination target object. A second probe coil for applying an alternating magnetic field perpendicularly from a second direction opposite to the one direction, and a first reference which does not cause a magnetic field to be incident on the object to be determined and is proportional to a current flowing through the first probe coil. First reference voltage generating means for generating a voltage, and second reference voltage generating means for generating a second reference voltage proportional to a current flowing through the second probe coil without causing a magnetic field to enter the object to be determined Means, a distance g1 in the first direction between the first probe coil and the object to be determined, and the second
The distance g2 between the probe coil and the object to be determined in the second direction is determined, and the distances g1 and g2 are subtracted from the distance Go between the two coils, so that the object in the first and second directions of the object to be determined is determined. A determining unit that determines the thickness t, wherein the determining unit determines the first and second reference voltages and the first and second reference voltages.
The total voltage of the second probe coil or its reactance voltage component (hereinafter collectively referred to as the voltage of the first and second probe coils) or the first and second reference voltages and the first and second reference voltages
Voltage detection means for detecting the first and second difference voltages between the voltage of the second probe coil and converting the voltage to an appropriate level or the like;
Distance g between the object to be determined and each probe coil
1 and g2, wherein the arithmetic unit detects or detects between the reference voltage Ea detected by the voltage detecting means and the voltage Eb of the probe coil detected by the voltage detecting means. Difference voltage ΔE
A first step of determining the material of the object to be determined based on the phase difference angle θ between the probe coil and the detected voltage Eb of the probe coil or the detected difference based on information of the determined material. Ratio Eb between voltage ΔE and reference voltage Ea
And a second step of determining distances g1 and g2 between the object to be determined and the respective probe coils based on / Ea and ΔE / Ea. 5. A thickness gauge for measuring the thickness of a conductive object made of a predetermined material, comprising: a power source for generating an AC voltage; and a power source connected to the power source, the surface of the object to be determined being viewed from a first direction. A first probe coil for vertically inputting an alternating magnetic field, and an object to be determined which is disposed opposite to the first probe coil at a predetermined distance Go in the first direction and opposite to the first probe coil and connected to the power supply; A second probe coil for applying an alternating magnetic field to the surface of the object perpendicularly from a second direction opposite to the first direction, and a current flowing through the first probe coil without causing a magnetic field to enter the object to be determined. A first reference voltage generating means for generating a proportional first reference voltage; and a second reference voltage generating means for preventing a magnetic field from being incident on the object to be determined and being proportional to a current flowing through the second probe coil.
A second reference voltage generating means for generating a reference voltage; a distance g1 in the first direction between the first probe coil and the object to be determined; and a distance g1 in the second direction between the second probe coil and the object to be determined. The distance g2 is determined, and the distance G between the two coils is determined.
a determination unit that determines the thickness t of the determination target object in the first and second directions by subtracting the distances g1 and g2 from o. The determination unit refers to the first and second references. Voltage and the first,
The total voltage of the second probe coil or its reactance voltage component (hereinafter collectively referred to as voltages of the first and second probe coils) or the first and second reference voltages and the first and second reference voltages.
Voltage detection means for detecting the first and second difference voltages between the voltage of the second probe coil and converting the voltage to an appropriate level or the like;
The voltage Eb of the probe coil detected by the voltage detecting means or the ratio Eb between the detected difference voltage ΔE and the reference voltage Ea detected by the voltage detecting means.
A thickness meter comprising: a calculation unit that determines distances g1 and g2 between an object to be determined and respective probe coils based on / Ea and ΔE / Ea. 6. The method according to claim 3, wherein the first probe coil and the second probe coil are arranged on the same axis so as to face each other,
A thickness gauge which is magnetically shut off from each other via an object to be determined during the measurement operation. 7. The circuit according to claim 1, wherein the reference voltage generating means has a circuit constant equivalent to that of the probe coil, and the same current flows as the probe coil. A reference coil connected to the reference coil, wherein the detection means of the reference voltage in the voltage detection means is a secondary coil magnetically coupled to the reference coil to induce a voltage proportional to a reactance component of the reference coil voltage;
The detecting means for detecting the reactance voltage component of the probe coil voltage in the voltage detecting means is a secondary coil magnetically coupled to the probe coil to induce a voltage proportional to the voltage component. Is a distance meter or a thickness meter which is arranged at a position or a direction in which a magnetic field does not enter the object to be determined, or is provided with a magnetic shield. 8. The distance meter or the thickness meter according to claim 1, wherein the power supply unit is a variable frequency power supply capable of changing a frequency f. 9. The power supply unit according to claim 1, wherein the power supply unit is a source of a composite wave voltage obtained by combining a plurality of sine wave voltages having different frequencies, and the arithmetic unit includes: , The reference voltage Ea and the voltage Eb of the probe coil or the difference voltage ΔE are sampled at high speed, and A
/ D conversion and frequency components f1,
f2,. . . A distance meter or a thickness meter which calculates the distance g1, g2 or the material of the object to be determined for each time and determines the distance or the thickness. 10. The object type determination device according to claim 1, wherein the object to be determined is embedded in a surface of a plastic card.