JP2000171204A - Distance measuring equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a thickness of a film or the like or a distance from a conductive substance in a simple manner by changing a distance between a distribution plane of an element having a distribution inductance interacting with the conductive substance such as a metal and a conductive substance opposite thereto in parallel. SOLUTION: When a distance between a surface of an inductor distributed two-dimensionally and a conductive substance 10 decreases, both are electrically coupled to each other. The distance between them is measured from a drop in inductance of the inductor 20 due to counteraction of electromagnetically induced current. A detection circuit constitutes an LC circuit 35 with a concentrated capacitor 30 connected in series with the inductor 20. An output signal form the LC circuit 35 is input via a transistor amplifier 31 to a feedback network 32 and a frequency counter 33. An output from the feedback network 32 is positively fed back to the inductor 20, and the frequency counter 33 outputs a distance measurement output signal 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring apparatus for measuring a distance or a thickness to a substance to be measured by measuring a distance to a metal or a conductive substance.

[0002]

2. Description of the Related Art X-ray,
There are methods using an electro-magnetic action, a laser beam, a micrometer, and the like. For example, as a method and an apparatus for measuring the thickness of a two-layer structure material, there is a method disclosed in JP-A-63-269008. In this method, X-rays are applied to the tube wall, and the thickness of the tube wall is measured based on the amount of transmission. In the method using an electromagnetic effect, a magnetic substance is placed on an object, and the distance between the coil and the coil is changed to measure the distance. In a micrometer, measurement is performed by bringing a probe into contact with the surface of a substance.

[0003]

The conventional method has the following problems. The equipment is complex, large and heavy and expensive. -When using the electromagnetic effect, a magnetic substance is required for the substance to be measured.・ In metal mold size inspection, since the metal surface reflects light,
Cannot use laser beam. -In a measurement method such as a micrometer, the surface of the substance to be measured is destroyed by contact. In addition, contact generates and wears out stress, causing an error. In addition, there are the following problems with a thickness gauge using X-rays.・ Use X-rays that are harmful to the human body.・ It is necessary to set a danger zone. -The operator needs qualification.・ There is a lot of noise. The conventional distance measuring apparatus has the above-described problems, and the present invention solves the problem of measuring the thickness of a film or the like or the distance to a conductive substance by a simple method.

[0004]

According to the present invention, the following means are taken to solve the above-mentioned problems. (1) A distance measuring IC (Intemet) including an element having distributed inductance that interacts with a conductive substance such as a metal.
A detection means including a detection circuit such as a graded circuit is used. (2) Use a conductive substance approaching means that changes the distance between a conductive substance such as a metal inside or outside the device and an element having distributed inductance according to the thickness of the substance to be measured. (3) Power supply means for supplying power to the entire apparatus and control means for controlling the apparatus are provided. (4) An output unit including a display unit or a signal output unit for displaying the detected distance is provided.

The reason for using a detection circuit such as a distance measuring IC including an element having distributed inductance is as follows. When the distance between the two-dimensionally distributed surface of the inductor and the conductive material decreases, the two are electrostatically coupled. Due to the canceling action of the electromagnetically induced current, the inductance of the inductor is reduced. The distance is measured using this. A high-sensitivity distance measuring device is realized by flowing a high-frequency current through a two-dimensionally distributed inductor and effectively utilizing electrostatic induction generated on the surface of the inductor. The performance is better because the use of electrostatic coupling requires less current than the use of electromagnetic coupling which requires a large amount of current. That is, the inductor of the distance measuring device is electrostatically coupled to the conductive material, and the inductor of the distance measuring device has a two-dimensional structure in order to maximize the effect. In order to effectively detect a phenomenon resulting from this effect, a distance measuring IC is used.

[0006]

The present invention has the following effects. (1) By using the distance measurement IC, a circuit for amplifying an analog signal and an A / D converter are not required, so that the price of the entire system is reduced. (2) The apparatus is simple, small, lightweight, and inexpensive. Further, it can be arranged in a narrow space. (3) Since the output of the distance measuring device is digital, even if the output line is lengthened, the measured value is not attenuated or affected by noise. (4) Since all of the distance measuring devices are digital circuits,
It is easy to realize with an integrated circuit. (5) When the substance to be measured is a conductive substance such as a metal such as a dimension inspection of a mold, a magnetic substance is unnecessary and the measurement can be performed as it is. (6) No wear due to non-contact measurement. In addition, no stress occurs due to contact, and no error occurs. (7) It is safe and easy to handle.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLE 1 FIG. 1 shows an example of a film thickness gauge embodying the present invention. The element 1 having the distributed inductance is installed inside the front end of the housing 6. First, the housing 6 is directly placed on the metal plate 3, and the display is set to “0.0” by the control button 4.
00 ”. Thereafter, a film or the like is placed on the metal plate 3 as the substance 2 to be measured, and
Is pressed, the thickness of the substance 2 to be measured is displayed on the display unit 5. FIG. 2 shows the internal structure and block diagram of this device. In the first embodiment, the means for approaching the conductive substance is substituted by the movement of the hand. However, it is also possible to automate using a robot manipulator, an air cylinder, or the like. In FIG. 2, power supply means for supplying energy including a power supply is omitted for simplification of the drawing.

FIG. 3 shows a block diagram of an example of a detection circuit in a distance measuring apparatus using an element 1 having inductors distributed two-dimensionally. The lumped capacitor 30 is connected in series to the two-dimensionally distributed inductors 20 to form an LC circuit 35. The output signal from the LC circuit 35 is input to the transistor amplifier 31. The output of the transistor amplifier 31 is input to a feedback network 32 and a frequency counter 33. An output signal of the feedback network 32 is positively fed back to the inductors 20 distributed two-dimensionally, thereby forming an oscillator. An output signal 34 of the distance measuring device of the present invention is output from the frequency counter 33.

Generally, inductors distributed two-dimensionally include a meander type and a spiral type. FIG. 4 shows an example in which meander-shaped two-dimensionally distributed inductors 20 are arranged on the surface of an insulating material 21. The inductors 20 distributed two-dimensionally are made using a conductive material such as copper.
Insulating materials are usually paper / phenol, glass / epoxy,
Made of printed circuit board materials such as ceramics.

FIG. 5 shows an example in which a two-dimensional spiral-shaped inductor 20 is arranged on the surface of an insulating material 21. A very high frequency current flows through the two-dimensional inductor used in the distance measuring IC of the present invention. Usually, a high frequency of 1 MHz to 1,000 MHz is used. At very high frequencies, the current flowing in the conductor flows to the surface of the conductor and does not flow inside. This phenomenon is called a skin effect. Since a high frequency is used to measure the distance at high speed, only the phenomenon that occurs near the surface of the inductor due to the skin effect can be used.

In FIG. 6, an insulating material 21 is disposed on the upper surface of an integrated circuit 22, an inductor 20 distributed two-dimensionally is disposed thereon, and a conductive material is applied to the inductor 20 distributed two-dimensionally. The case where the substance 10 approaches is shown. When the conductive material 10 approaches the two-dimensionally distributed inductor 20, the current flowing through the inductor 20 changes. By measuring the change in the current, it is possible to measure the distance between the conductive material 10 and the inductors 20 distributed two-dimensionally.

FIG. 7 shows the electrostatic induction 25 generated when the distance d between the conductive substance 10 and the inductor 20 distributed two-dimensionally is large by broken lines and arrows, and the magnetic force lines 24 generated by the current by solid lines and arrows. Indicated by Since the current flowing through the inductors 20 distributed two-dimensionally is small, the generated lines of magnetic force are small. When a current flows through the inductors 20 distributed two-dimensionally, electrostatic induction occurs on the surface of the conductive material 10. As shown in FIG. 7, when the distance d is large, the effect of electrostatic induction is weak, and thus the value of the capacitance of the distributed capacitor generated between the conductive material 10 and the inductor 20 distributed two-dimensionally is small. . The current flowing through the two-dimensionally distributed inductors 20 generates lines of magnetic force, but the distance d
, The electromagnetic coupling is weak.

FIG. 8 shows an electrostatic induction 25 generated when the distance d between the conductive material 10 and the inductor 20 distributed two-dimensionally is short. As shown in FIG. 8, when the distance d decreases, the two-dimensionally distributed inductors 20 and the conductive material 10 are strongly coupled electrostatically inductively. Since the electrostatic induction is increased, the value of the capacitance of the distributed capacitor generated between the conductive material 10 and the inductor 20 distributed two-dimensionally increases.

FIG. 9 shows a distribution capacitor 26 generated between the conductive material 10 and the inductor distributed two-dimensionally. This figure is a cross-sectional view in the X-axis direction when the direction in which current flows through the element 1 having inductors distributed two-dimensionally is the X-axis. On the insulating material 21, there is an inductor distributed in a two-dimensional manner, and since a voltage is applied to the inductor, electric charges are generated. The generated charges are represented by plus and minus signs. When the distance d between the conductive material 10 and the two-dimensionally distributed inductor is reduced, the effect of electrostatic induction is increased, and the distributed capacitor 26 generated between the conductive material 10 and the two-dimensionally distributed inductor is generated. Becomes large. Therefore, due to the effect of electrostatic induction, charges having a sign different from that of the inductor distributed two-dimensionally appear in the conductive material 10. Conductive substance 1
The charge induced in 0 is represented by plus and minus signs.

FIG. 10 shows a cross section in the X-axis direction of an element 1 having a conductive substance 10 and inductors distributed two-dimensionally. On the insulating material 21 is a two-dimensionally distributed inductor, through which a current i flows. Due to the effect of electrostatic induction, charges having a sign different from that of the inductor distributed two-dimensionally appear in the conductive material 10. The current flowing through the induced charge is denoted by I. The direction in which the current I flows and the direction in which the current i flows are opposite. As the distance d decreases, the current I flowing through the conductive material 10 increases. The current i flowing through the two-dimensionally distributed inductors generates lines of magnetic force in space, and the generated lines of magnetic force are electromagnetically coupled with the current i to form self-inductance. The self-inductance corresponds to the inductance L of the inductor distributed two-dimensionally. However, the current I flowing through the conductive material 10 also generates magnetic force lines in the space. Since the direction of the current I and the direction of the current i are opposite,
The direction of the line of magnetic force in which the current I is generated is opposite to the direction of the line of magnetic force in which the current i is generated. Therefore, the magnetic field lines in which the current i is generated are canceled by the magnetic field lines in which the current I is generated,
Become smaller. Therefore, when the conductive material 10 approaches the element 1 having the two-dimensionally distributed inductors, the inductance L of the element 1 having the two-dimensionally distributed inductors is equivalently reduced. Conversely, when the distance d increases,
The inductance L also increases equivalently. Therefore, when the change in the inductance L is measured, the change in the distance d can be measured. Therefore, according to FIG. 3, in the distance measuring device of the present invention, when the inductance L changes, the frequency f of the oscillator also changes. Therefore, by measuring the frequency f using the frequency counter 33, the two-dimensional distribution It is possible to measure the distance d between the inductor and the conductive material.

Generally, when the frequency of the current flowing through the electric circuit increases, the current flowing through the inductor decreases and the current flowing through the capacitor increases. The distance measuring device of the present invention uses inductors distributed two-dimensionally. Therefore,
When a conductive material approaches the inductor, the conductive material and the inductor are electrostatically coupled. As shown in FIG. 10, the inductor serves as one electrode of the distributed capacitor, and the conductive material serves as the other electrode of the distributed capacitor, so that the two are electrostatically coupled. Therefore, as shown in FIG. 9, when the distance between the conductive material and the inductor is reduced, the capacitance of the distributed capacitor is increased. Therefore, when the frequency of the current flowing through the circuit is high, the current flowing through the conductive material via the distribution capacitor increases. The magnetic flux generated by the current flowing through the conductive material and the magnetic flux generated by the current flowing through the inductor are electromagnetically coupled and cancel each other.
Therefore, the inductance of the inductor distributed two-dimensionally decreases equivalently. The frequency f of the oscillator determined by the inductance L of the inductor distributed two-dimensionally and the capacitance C of the lumped capacitor is represented by the following equation. f × f × L × C = (1 / 2π) × (1 / 2π) (1) Based on the expression (1), the inductance L of the inductor 1
Decreases, the frequency f of the oscillator increases. The frequency f of the oscillator can be measured using a frequency counter. When the conductive material approaches the two-dimensionally distributed inductor and the distance between the two decreases, the capacitance of the distributed capacitor increases, and the current flowing through the conductive material increases. Therefore, the strength of the electromagnetic coupling also increases. Due to these canceling effects, the inductance L of the inductor distributed two-dimensionally is reduced equivalently. Therefore, when the change in the frequency f of the oscillator is measured, the change in the distance between the conductive material and the inductor distributed two-dimensionally can be measured.

FIG. 11 shows an example of the transistor amplifier 31 used in the present invention. The transistor amplifier 31 has an input Vin and an output Vout. The input Vin is input to the gate of the driving transistor Q1, and the drain of the driving transistor Q1 is connected to the load transistor Q1.
2 are connected. The power supply voltage Vdd is connected to the drain of the load transistor Q2, and the source of Q2 is the output Vout. The signal input to the input Vin is amplified and output from the output Vout. In the distance measuring device of the present invention, all transistors such as a bipolar transistor and a field effect transistor can be used, and the type of the transistor is not limited.

FIG. 12 shows an example of the feedback network 32 using a resistor. Feedback network 32 is comprised of resistors R1 and R2.
The signal input to Vin of the feedback network 32 is attenuated and output from Vout.

[0019]

Embodiment 2 FIG. 13 shows a stapler type thickness gauge as an embodiment having a variable distance structure with respect to a metal installed inside the apparatus as a conductive substance approaching means. Working principle is Example 1
Same as above, but using a metal piece 3 embedded in the lower hand portion as the conductive substance to be detected. The substance to be measured is sandwiched between the lower hand part and the upper hand part, and the substance to be measured is sandwiched between the element 1 having a two-dimensionally distributed inductor 1 and the metal piece 3 by bringing the two hand parts close to each other. And the thickness of the substance to be measured can be measured. In the case of this embodiment, since a conductive material such as a metal plate opposed to the element 1 having a two-dimensional inductance is previously installed inside the device, there is no need to separately prepare a conductive material.
Measurement can be performed easily.

[0020]

Embodiment 3 FIG. 14 shows an example of a thickness gauge used in an inspection process in a plastic sheet or film production line. As a conductive material access means, a metal movable roller 41
And a support mechanism 44 is used. The sheet or the film is passed between the fixed roller 42 and the movable roller 41. The position of the movable roller 41 changes in accordance with the thickness of a sheet or a film on a circumferential orbit about the fulcrum 45.
The thickness of the sheet or the film is measured by measuring the distance from the movable roller 41 using the detection unit 40 incorporating the element 1 having the inductance distributed two-dimensionally. The distance measurement device illustrated in the first embodiment may be used for the detection unit 40. Note that the detection unit 40 may be attached below the support mechanism 44. In this case, a conductive substance such as a metal is attached to the support mechanism 44 on the surface facing the detection unit, or the support mechanism 44 is made of a conductive substance, and the distance to the conductive substance is measured by the detection unit. Measure. Further, the pressing spring 46 above the support mechanism 44 may be a pull spring below the support mechanism. Alternatively, it is also possible to substitute an electromagnetic force of an electromagnetic solenoid or the like, a magnetic force of a permanent magnet, air pressure, gravity, or the like.
The positional relationship between the fixed roller 42 and the movable roller 41 is as follows.
It does not matter whether it is up, down, left or right, and is not limited to this example.

[0021]

Embodiment 4 FIG. 15 shows an example of a thickness gauge used in an inspection process in a production line for metal parts. The conductive substance access means includes an inspection table 51, a highly rigid support arm 52 to which the detection unit is fixed, and a robot 53 for placing metal parts on the inspection table. In the detection unit 40,
An element having a two-dimensionally distributed inductance is built in, and the distance to a metal can be measured by a detection circuit. The metal part 50 is conveyed by the conveyor 54 and picked by the robot 53 at a predetermined position. The picked metal component is placed on the inspection table 51, and the distance between the metal component and the detection unit is measured by the detection unit 40 on the support arm 52. Thereby, the height of the metal part is measured. The metal part is returned to the conveyor 54 again by the robot 53 after obtaining statistical management data and making a pass / fail judgment. In this example,
The detection unit is fixed using the support arm, and the metal component is moved to the inspection table using the robot. Conversely, the detection unit may be moved without moving the metal component. It is also possible to measure the thickness of the intricate part of the metal component by bringing the detection unit close to the metal component being transported by using a mechanism with high repeatability. In addition, for continuous materials such as rolled materials, and for the thickness of long objects, the mechanism for access means for conductive substances can be more easily made by installing support arms so as to span the transport line. it can. In this example, metal is exemplified as the substance to be measured.However, it is possible to detect any conductive substance such as fine carbon powder or resin having conductivity by mixing metal powder. It is not limited to the example.

[Brief description of the drawings]

FIG. 1 shows an example of a thickness gauge in which a substance to be measured is sandwiched between a metal plate and a metal plate.

FIG. 2 shows a block diagram of a thickness gauge in which a substance to be measured is sandwiched between a metal plate and a metal plate.

FIG. 3 shows an example of a block diagram of a detection circuit in a distance measuring device using inductors distributed two-dimensionally.

FIG. 4 is a perspective view of an example in which meander-type two-dimensionally distributed inductors are arranged on the surface of an insulating material.

FIG. 5 is a perspective view in which spiral-shaped two-dimensionally distributed inductors are arranged on the surface of an insulating material.

FIG. 6 is a perspective view showing a state in which an insulating material is arranged on an upper surface of an integrated circuit, a two-dimensionally distributed inductor is arranged thereon, and a conductive material approaches the two-dimensionally distributed inductor.

7 shows a cross section of the two-dimensional inductor and the conductive material of the distance measuring IC shown in FIG. 6 in the Y-axis direction.

FIG. 8 is a cross-sectional view showing a state where a conductive substance has approached the two-dimensional inductor of the distance measuring IC shown in FIG. 6;

9 shows a cross section in the X-axis direction of the two-dimensional inductor and the conductive material of the distance measuring IC shown in FIG.

FIG. 10 is a schematic view showing a current generated by a two-dimensional inductor of the distance measuring IC shown in FIG. 6 and a charge electrostatically induced in a conductive material.

FIG. 11 is a circuit diagram showing an example of an amplifier used for a distance measurement IC.

FIG. 12 shows a feedback signal used for a distance measurement IC.
FIG. 2 is a circuit diagram illustrating an example of a network.

FIG. 13 shows an example of a stapler-type thickness gauge having a structure in which the distance from a metal plate installed inside the apparatus is variable.

FIG. 14 shows an example of a thickness gauge used in an inspection process in a plastic sheet or film production line.

FIG. 15 shows an example of a thickness gauge used in an inspection process in a production line for metal parts.

[Explanation of symbols]

 Reference Signs List 1 Element having inductance distributed in two dimensions 2 Substance to be measured 3 Metal plate or metal piece 4 Control button 5 Display unit 6 Housing 10 Conductive substance 11 Detection means including distributed inductance 12 Conductive substance access means 13 Control means Reference Signs List 14 output means 20 two-dimensionally distributed inductor 21 insulating material 22 IC 23 pin of IC 24 magnetic field line generated by current 25 electrostatic induction 26 distributed capacitor 30 lumped capacitor 31 amplifier 32 feedback network 33 frequency counter 34 output signal 35 LC circuit 40 Detection unit 41 Metal movable roller 42 Fixed roller 43 Film or sheet 44 Support mechanism 45 Support point 46 Push spring 50 Metal part 51 Inspection table 52 Support arm 53 Robot 54 Conveyor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA16 AA22 AA23 BB02 BC09 CA08 CA34 DA01 DA02 DA05 GA03 GA27 HA01 KA01 KA02 LA05 LA15

Claims (5)

[Claims] Claims: 1. An element having a distributed inductance,
A detecting means comprising a detecting circuit which reacts according to the distance between the conductive substance and the element having the distributed inductance; a conductive substance parallel to the distribution surface of the element having the distributed inductance; and an element having the distributed inductance. A conductive substance approaching means comprising a mechanism for changing the distance of the object, a power supply means for supplying energy to the detecting means, a control means for controlling the device, and an output means for displaying a signal indicating the detected distance and outputting a signal A distance measuring device comprising: 2. A conductive substance access means is a mechanism for changing a distance between a conductive substance previously installed in a casing of an apparatus and an element having a distributed inductance with the conductive substance. The distance measuring apparatus according to claim 1, wherein the thickness of the measured substance is measured by positioning the measured substance in the gap. 3. The distance measuring apparatus according to claim 1, wherein the conductive substance approaching means is a mechanism for changing a distance between an element having distributed inductance and a conductive substance located outside the apparatus. 4. The conductive substance approaching means comprises an inspection table, an element having a distributed inductance positioned at a predetermined distance from the inspection table, and a mechanism for installing the conductive substance on the inspection table. The distance measuring device according to claim 1, wherein a distance between the element having distributed inductance and the conductive material changes according to a thickness of the conductive material placed on the inspection table. 5. The detecting means according to claim 1, wherein the detecting means includes an element having a distributed inductance, and a detecting circuit responsive to a distance between the conductive substance and the element having the distributed inductance and a change amount of the distance. Distance measuring device.