JP2717778B2 - Apparatus and method for measuring thickness of insulating film formed on moving metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for measuring the thickness of an insulating film formed on a moving metal plate by a hybrid structure of a capacitance system and an eddy current system. It is. In recent years, high-precision thickness control of the thickness of the adhesive applied to the metal plate, the thickness of the ink applied to the metal plate, and the thickness of the coating that insulates the metal plate has been demanded. And the adhesive coating on the metal plate, ink, or insulating coating such as coating,
The metal plate is being processed while moving at high speed. Therefore,
The present invention provides a measuring apparatus and a measuring method capable of measuring the thickness of an insulating film formed on a metal plate moving at a high speed as described above with high accuracy.

[0002]

2. Description of the Related Art FIG. 5 is for explaining a conventional example.
FIG. 3 is a schematic view of the principle for measuring the thickness of an insulating film formed on a moving metal plate. For example, the measuring device shown in FIG. 5 measures the thickness of the insulating film 22 coated on the metal plate 21. The sensor section 23 for measuring the insulating film 22 is composed of a pair of a main electrode 24 for capacitance and a core 25 for eddy current. The main electrode 24 for capacitance and the core 25 for eddy current are detachably attached by well-known fixing means. Further, the capacitance main electrode 24 and the eddy current core 25 can be slid so that the mounting position can be changed. The lower surfaces of the capacitance main electrode 24 and the eddy current core 25 are configured to be flush with each other. The capacitance main electrode 24 and the eddy current core 25 are connected to a measuring device (not shown) via an output 26 thereof.

[0003] On the base 27, the metal plate 21 on which the insulating coating 22 is formed moves. The metal plate 21 may float during the movement, for example, by a distance a shown in FIG. However, the measurement device calculates on the basis of the capacitance at a predetermined distance a + b. Therefore, the distance a + b
An error occurs between the thickness obtained by the calculation based on the equation (1) and the actual thickness d of the insulating film 22. In order to eliminate this defect, first, the distance c between the metal surface and the lower portion of the eddy current core 25 is measured by the eddy current core 25. Then, a correction value setting unit of the measuring device (not shown) obtains a displacement a from a preset distance between the eddy current core 25 and the base 27, and based on the displacement a, a correction value of the capacitance. Set. Thereafter, the capacitance main electrode 24 and the metal plate 21 are detected by a capacitance detection unit of a measuring device (not shown).
Is measured at a distance b with respect to. The thickness calculator of the measuring device (not shown) calculates the thickness based on the capacitance at the actual distance b and the previously obtained correction value instead of the capacitance at the reference distance a + b.

FIG. 6 is a view for explaining the principle of measuring the distance between the sensor section and the metal plate using eddy current. In FIG. 6, the distance measuring device includes a coil 32 set to face a metal plate 31 and a measuring unit 33. Then, the measuring unit 33 generates an eddy current in the metal plate 31 by flowing the high-frequency current through the coil 32 and an oscillating circuit 331 for flowing the high-frequency current through the coil 32, and the eddy current changes. Coil 32
And a calculation circuit 3 for calculating the distance h between the metal plate 31 and the coil 32 in consideration of the type of the object to be measured or the dimensions of the coil 32 and the like.
33, and a power supply circuit 334 for supplying current to each circuit.

The distance measuring device shown in FIG.
An electric current is passed from 1 to the coil 32 facing the metal plate 31.
The current flowing through the coil 32 generates an electric field and an eddy current on the surface of the metal plate 31 by electromagnetic induction. The eddy current causes the coil 32 to generate an induced current. Measuring unit 33
The detection circuit 332 detects the impedance of the coil 32 as viewed from the detection circuit 332. Coil 32
The impedance seen from the detection circuit 332 of the coil 3
It changes depending on the distance between 2 and the metal plate 31. Therefore, the arithmetic circuit 333 calculates the electric conductivity, the magnetic permeability,
If you take into account the thickness, temperature, coil size, etc.
From the output voltage 34 of the arithmetic circuit 333, the distance between the metal plate 31 and the coil 32 can be measured in μm.

FIG. 7 is a diagram for explaining the principle of a thickness gauge in the capacitance system. In FIG. 7, the thickness gauge
The main electrode 41 and the counter electrode 42 are provided to measure the capacitance. The insulating coating 43 formed on the metal plate 43 ′ is arranged between the main electrode 41 and the counter electrode 42. The counter electrode 42 is mounted or mounted on a base 44 or the like. A sliding rod 45 provided on the base 44 has a supporting rod 46 which is slidably movable in the vertical direction.
Is attached. The support rod 46 has an external holder 47 that holds the main electrode 41 in an insulated state.
Has been fixed. The measuring device 48 includes a power supply circuit (not shown) for applying a voltage to the main electrode 41 and the counter electrode 42, an oscillation circuit, a detection circuit for detecting capacitance, and a calculation circuit for calculating the thickness.

In such a thickness gauge, when, for example, a resin film is inserted between the main electrode 41 and the counter electrode 42 as the insulating film 43 to be measured, the main electrode 41 and the counter electrode 42 And the capacitance between them changes. Therefore, the capacitance of the resin film having a known thickness is measured in advance, and the capacitance is measured based on the capacitance and the capacitance value detected from the resin film as the object 43 to be measured. An arithmetic circuit in the device 48 performs a comparison operation to determine the thickness of the resin film.

In recent years, it has become necessary to measure the thickness of a coating film such as a resin film formed on a moving metal plate. FIG. 8 is an explanatory diagram for measuring the thickness of a resin film formed on a moving metal plate by a measuring method in a conventional example. 8, the metal roller 52 is rotated by a rotation shaft 53. The metal roller 52 rotates while coating the surface thereof with a resin film 54. The thickness of the resin film 54 formed on the rotating metal roller 52 is determined by the capacitance measured by applying a voltage to the capacitance main electrode 51 and the metal roller 52.

FIG. 9 is an explanatory diagram for measuring the thickness of a wide resin film formed on a metal plate by the measuring method in the conventional example. In FIG. 9, for example, a plurality of capacitance main electrodes 62 to 65 are installed on the same main surface of the support member 61 for capacitance main electrode with the sensor section facing downward. The thickness of the insulating coating 67 formed on the surface of the metal plate 66 is measured at various points on the insulating coating 67, and this value is sent to a control device, for example, to control the thickness.

[0010]

The distance measuring device shown in FIG. 6 measures the distance, and cannot measure the thickness of the insulating film formed on the metal plate 31. Also,
The capacitance meter shown in FIG. 7 can measure the thickness of the insulating coating 43 formed on the metal plate as long as the metal plate does not move vertically. However, the insulating coating 43
Is formed on the metal plate 43 ', it is not always at a constant height during movement. Therefore, the metal plate 43 '
If the insulating film 43 formed on the upper surface is moved up and down, the reference distance for measuring the capacitance changes, so that it is impossible to accurately measure the thickness. I had. In particular, when the rotating shaft 53 of the metal roller 52 vibrates in the direction of the arrow 55 in the figure, for example, the resin film 54 formed on the surface of the metal roller 52 as shown in FIG. There is a problem that an error can occur in the measured thickness for the same reason as described above.

Further, the thickness of the insulating film 67 formed on the metal plate 66 can be accurately measured at various locations in the width direction by the plurality of capacitance main electrodes 62 to 65 shown in FIG. . However, the insulating coating 67 formed on the metal plate 66 may be displaced vertically from the base 68 during movement. In this case, it is difficult to measure the distance 71 between the metal plate 66 and the base 68 and accurately correct the thickness of the insulating coating 67 from this value. Therefore, the measuring apparatus shown in FIG. 9 calculates the thickness 70 of the insulating coating 67 from the distance 69 ignoring the distance 71 and the measured capacitance.

When measuring the thickness of the insulating film 67 formed on the metal plate 66 by the capacitance in the conventional example shown in FIG. 9, the capacitance main electrodes 62 to 65 are used.
The distance between the base and the base 68 changes according to temperature changes such as time and date. Therefore, such a thickness gauge performs high-accuracy measurement by always adjusting the correct distance (0 adjustment). However, in recent years, there has been a demand for higher-precision measurement, and an error due to a temperature difference in a day becomes a problem. In this case, it is necessary to stop the production line several times a day to perform zero adjustment, which causes a problem of lowering productivity.

To solve the above problem, FIG.
In the conventional example shown in (1), the number of zero adjustments to be performed at the start of measurement is small, and an accurate thickness can be measured even when the metal plate is moved up and down while moving. However, if the distance between the metal plate and the lower surface of each electrode is larger than the distance between the main electrode for capacitance and the core for eddy current, accurate measurement of the thickness may not be possible. The reason is that an error occurs in the measurement because the place where the capacitance is measured does not match the place where the distance due to the eddy current is measured. The present invention has been made to solve the above problems, and has a common main electrode for capacitance and a core for eddy current.
The thickness of the insulating film formed on the moving metal plate can be accurately measured even when the metal plate moves vertically while moving. An object of the present invention is to provide a thickness measuring device and a measuring method thereof.

[0014]

[Means for Solving the Problems]

(1st invention) In order to achieve the above object, the present invention provides an apparatus for measuring the thickness of an insulating film formed on a moving metal plate, comprising: an insulating film formed on a moving metal plate (21); Coating
The main electrode for capacitance and the core for eddy current comprising a conductor member and an eddy current coil (16) wound around the conductor member. And a guard electrode (13) provided on the same plane as the sensor section (11) and provided insulated from the sensor section (11), and the guard electrode (13). ) On top of the insulating material (1
4) The plate-like ground electrode (15) placed via the eddy current core (11), by measuring the displacement of the surface of the metal plate (21) and the eddy current core (11), A correction value setting unit for obtaining a correction distance between the surface of the metal plate (21) and the eddy current core (11), and the capacitance main electrode (11) and the surface of the metal plate (21) for the capacitance. A capacitance detection unit for measuring the capacitance between the main electrode (11) and the metal plate (a value obtained from the capacitance detection unit by the correction value obtained from the correction value setting unit; 21) a thickness calculator for calculating the thickness of the insulating coating (22) on the upper surface.

(Second and Third Inventions) The conductor member may be an amorphous metal. Further, in the present invention, the apparatus for measuring the thickness of the insulating film formed on the moving metal plate includes a concave portion (1) formed on the conductive member.
1 ′) The sensor unit (11), which also serves as the main electrode for capacitance and the core for eddy current, provided with the eddy current coil (16) wound around the protrusion (11 ″) formed by Features.

(Embodiment 4) In the present invention, an apparatus for measuring the thickness of an insulating film formed on a moving metal plate comprises an eddy current wound around an insulating hollow bobbin (17 in FIG. 2). A coil (16), a conductor member (213 in FIG. 2) provided around the eddy current coil (16) via a first insulating member (172 in FIG. 2), and a conductor member (213 in FIG. 2). 213) and a shield / capacitance main electrode (212 in FIG. 2) provided via a second insulating member (173 in FIG. 2) and the shield / capacitance main electrode (212). Guard electrode (13) provided via a third insulating member (174 in FIG. 2)
And a plate-like ground electrode (15) placed above the guard electrode (13) via a fourth insulating member (14), and the eddy current coil (16). A correction value setting unit that measures a displacement between the surface and the shield / capacitance main electrode (212) and obtains a correction distance between the surface of the metal plate (21) and the shield / capacitance main electrode (212); A capacitance detector for measuring a capacitance between the surface of the metal plate (21) and the shield / capacitance main electrode (212) by the shield / capacitance main electrode (212); A thickness calculating unit configured to calculate the thickness of the insulating film (22) on the metal plate (21) based on the correction value obtained from the correction value setting unit based on the value obtained from the capacitance detecting unit. Is done.

(Fifth invention) The method for measuring the thickness of an insulating film formed on a moving metal plate according to the present invention comprises the steps of: measuring an eddy current core (11 or 211) and a metal plate (21 ) And the main electrode for capacitance (11 or 21)
After measuring the capacitance between 2) and the surface of the metal plate (21), the capacitance is corrected by the displacement between the eddy current core (11 or 211) and the surface of the metal plate (21). The thickness is calculated from the corrected capacitance.

[0018]

[Function] The present invention focuses on an eddy current meter that can accurately measure the distance between a metal plate and an electrode even when an object to be measured moving at high speed is moved up and down. In common with an electrode of a capacitance meter for measuring the thickness of the capacitor. That is, the eddy current core and the capacitance main electrode are configured in common, and one electrode has both functions. This electrode can have good magnetic properties by employing, for example, an amorphous metal. An eddy current coil is insulated around the electrode. In addition, the sensor unit serving both as the eddy current core and the capacitance main electrode is formed of a concave portion and a projecting portion in which a coil can be wound. For example, the sensor section serving both as the eddy current core and the electrostatic capacity main electrode has a horseshoe-shaped cross section, and a coil that generates an eddy current is wound around the protruding section, thereby providing a stronger eddy current. A current can be generated.

The strong eddy current can accurately measure, for example, the distance to a moving object to be measured, so that the thickness of the insulating film formed on the surface of the object to be measured can also be accurately measured. Around the sensor part which also serves as the eddy current core and the capacitance main electrode, there is a guard electrode which is insulated from the ground electrode and insulated from the electrode. Due to the presence of the guard electrode, lines of electric force exiting from the main electrode for capacitance become perpendicular to the counter electrode or the metal plate. Therefore, the lines of electric force crossed by the insulating film, which is the object to be measured, are always constant, so that accurate capacitance can be measured.

When measuring the thickness of the insulating film formed on the moving metal plate, the correction value setting unit determines the displacement from the surface of the metal plate to the capacitance main electrode by using the eddy current core. , And calculates a distance deviated from the reference distance, and sets this as a correction value. After that, the capacitance detection unit, between the main electrode for capacitance and the surface of the metal plate,
The capacitance when an insulating film is interposed is measured. Capacitance can be measured accurately because the lines of electric force coming out of the main electrode for capacitance are perpendicular to the metal plate by guard electrodes of the same potential provided around the main electrode for capacitance. . Further, the calculation unit corrects the capacitance detected by the capacitance detection unit based on the correction value obtained by the correction value setting unit, and calculates the thickness of the insulating film.

As described above, the present invention provides a measuring system in which a main electrode for capacitance and a core for eddy current are used in common, even if the metal plate is shaken up and down while moving. The thickness of the insulating film formed thereon can be accurately measured. Further, the eddy current sensor includes an eddy current coil, a first insulating member, a tubular conductor, a second
The insulating member, the shield / capacitance main electrode, and the third insulating member were sequentially laminated. The thickness measuring device using the eddy current sensor having the above-described configuration can use not only a commercially available eddy current sensor but also a light weight due to the hollow insulating bobbin.

[0022]

[Embodiment] FIG. 1A is a view for explaining a sensor unit for measuring a thickness in an embodiment of the present invention. FIG. 1B is a block diagram for explaining an apparatus or method for measuring the thickness of an insulating film formed on a moving metal plate according to an embodiment of the present invention. In FIG. 1A, a main electrode for capacitance and a core for eddy current are made of a conductive member, and are configured as a sensor unit 11 having, for example, a quadrangular or cylindrical shape. A coil 16 for generating an eddy current is wound around the sensor section 11 via an insulating layer or an insulating hollow bobbin 17, for example. The insulating layer 17 and the sensor unit 11 are fixed with an adhesive or a screw. The bobbin 171 that protects the coil 16 is inserted into the recess 18 of the guard electrode 13 together with the coil 16 and the sensor unit 11 and then fixed with an adhesive or a screw. Attachment of the sensor unit 11, the insulating layer 17, the coil 16, and the guard electrode 13 includes press-fitting and the like in addition to the adhesive and the screw.
And the lower surface of the guard electrode 13 are flush with each other.

On the guard electrode 13, an earth electrode 15 is provided via an insulating member 14. Then, the sensor section 11 and the guard electrode 13 are connected so as to have the same potential at a position not shown in the figure and at a location not shown. The sensor section 11 and the guard electrode 13 are provided so as to face the base 12, and the metal plate 21 coated with the insulating film 22 moves between them. In addition, the sensor unit 11 can employ an amorphous metal in addition to a conductive member such as a ferromagnetic material. Amorphous metal, for example,
There are iron-phosphorus alloys, iron-boron alloys, and the like, which can improve magnetic properties. Further, the sensor unit 11 is connected to the lead wire 191 and the coil 16 is connected to the lead wire 192,
By 193, they are respectively insulated and connected to connectors (not shown). The lead wire 191 and the guard electrode 13 are connected to the same potential at a location not shown.

In FIG. 1B, the sensor unit 111 includes:
The capacitance main electrode and the eddy current core constitute a common measuring unit. Then, the correction value setting unit 112
Calculates the eddy current generated in the metal plate 21 by the high-frequency current, and calculates the floating distance of the metal plate 21 from the base 12 by an arithmetic circuit (not shown). This calculation result is an accurate capacitance correction value. on the other hand,
The capacitance detection unit 113 detects the capacitance of the insulating coating 22 existing between the sensor unit 11 and the metal plate 21.
Thereafter, the capacitance is calculated by the calculation unit 114 based on the distance by the correction value setting unit 112. The calculation unit 114 calculates the correct thickness of the insulating film 22 by referring to data on the dielectric constant of the insulating film 22 or temperature compensation, which is stored in the database 115 in advance.

Then, the calculated thickness of the insulating film 22 is digitally displayed on the display unit 116 as necessary. As described above, the measuring apparatus including the sensor unit 111 in which the capacitance main electrode and the eddy current core are common can be used even if the metal plate 21 is displaced up and down from the base 12 during movement. The thickness of the insulating film 22 formed on the metal plate 21 is accurately measured in order to measure the displacement between the metal plate 21 and the main electrode for capacitance with the eddy current core and to correct the displacement by an arithmetic circuit. be able to.

FIG. 2 shows another embodiment of the main electrode for capacitance.
It is a specific detailed explanatory view of a sensor part. FIG. 3 is an overall schematic view of the capacitance main electrode shown in FIG.
FIG. 2 is a diagram omitting an object to be measured and a base. 2 and 3, the sensor unit 211 includes an insulating hollow bobbin 1.
7, an eddy current coil 16 wound around the insulating hollow bobbin 17, a first insulating member 172, a tubular conductor 213 that passes a magnetic field, a second insulating member 173, a shield / capacitance main electrode 212, And the third insulating member 174 are sequentially stacked. In addition, the shape of the sensor unit 211 does not necessarily have to be circular, but may be a quadrangle. Such a sensor unit 211 includes a third
The concave portion 18 of the guard electrode 13 is formed via the insulating member 174.
, For example, with an adhesive or a screw. 2 and 3, the member denoted by reference numeral 213 can be a shield and main electrode. At this time, the member denoted by reference numeral 212 can be a guard electrode or can be omitted. Further, when the member denoted by reference numeral 212 is the main electrode, the member denoted by reference numeral 213 serves as a shield.

The guard electrode 13 and the shield / capacitance main electrode 212 are provided to face the base 12, and the metal plate 21 coated with the insulating film 22 moves between them. Further, the guard electrode 13 and the shield / capacitance main electrode 212 are insulated and connected to a connector (not shown) by a lead wire 191 and the coil 16 by lead wires 192 and 193, respectively.
The lead wire 191 and the guard electrode 13 are connected to the same potential at a location not shown. When a high-frequency current flows from the lead wires 192 and 193 to the eddy current coil 16, a magnetic field is generated from the center of the eddy current coil 16 through the tubular conductor 213 to return to the original position. Then, an eddy current is generated in the magnetic field and the metal plate 21.

Further, the shield / capacitance main electrode 212
Shields the magnetic field and serves as a main electrode of the capacitance meter. The thickness measuring device having such a configuration can accurately measure the capacitance even if it floats up during the movement in the same manner as in FIGS. 1A and 1B, so that the thickness is accurately calculated. . The embodiment shown in FIG. 2 and FIG.
The sensor unit 211 is the same as that used in a commercially available eddy current meter, and by incorporating a ready-made product into a capacitance meter,
An inexpensive and lightweight thickness measuring device can be obtained.

FIG. 4 is a schematic illustration of another embodiment of the sensor section of the main electrode for capacitance, in which the object to be measured and the base are omitted. The guard electrode 13 is formed with, for example, a recess 13 ′ into which the horseshoe-shaped sensor unit 11 is inserted and an opening 13 ″ for leading out the lead wires 191 to 193. An opening 15 'is formed for insulation and leads the lead wires 191 to 193 in the same manner as described above, and the sensor section 11 and the guard electrode 13 are separated from the lower surface of each electrode by a distance (not shown). At the same location.

On the other hand, the horseshoe-shaped sensor section 11 is composed of a concave section 11 'for winding a coil 16 for generating an eddy current and a projecting section 11 ". The coil 16 is attached to the projecting section 11". Although it is wound through an insulating member, it can be wound around the entire sensor part 11 other than the above-mentioned protruding part 11 ″. It is also possible to deform such as a state directed toward. In FIG. 4, the distance between the sensor unit 11 and the guard electrode 13 is large because of the schematic view. However, it is desirable that the actual sensor unit 11 and the guard electrode 13 sandwich the coil 16 and be as narrow as possible. If the distance between the two is large, the lines of electric force coming out of the sensor unit 11 may be bent, and it is impossible to achieve accurate capacitance. The sensor unit shown in FIG. 4 is the same as that shown in FIG.
Since the number of turns of the coil can be increased more than the sensor unit 11 shown in FIG. 1, a strong eddy current can be generated, and the displacement to the measured object can be accurately measured.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments. And
Various design changes can be made without departing from the invention as set forth in the appended claims. For example, the attachment of the sensor unit including the main electrode for capacitance and the core for eddy current, the coil for eddy current, the insulating hollow bobbin, the guard electrode, etc. can be variously deformed by known or well-known means other than the embodiment. it can. In addition, by providing a plurality of capacitors having a common main electrode for capacitance and a core for eddy current and arranging them in the width direction of the metal plate, the thickness of the insulating coating formed on the wide metal plate can be accurately determined. Can be measured. By doing so, it is not necessary to scan the capacitance main electrode and the eddy current core in the width direction of the metal plate.

In the embodiment, the number of guard electrodes is one, but a second guard electrode or a third guard electrode is provided outside the guard electrode of the embodiment via an insulating member, and the third guard electrode is provided. An earth electrode can be provided on the guard electrode via an insulating member. In this case, the guard electrodes other than the ground electrode are on the same plane as the main electrode for capacitance, and are connected to the same potential at a position away from the lower surface. As described above, when a plurality of guard electrodes are provided around the main electrode for capacitance, the electric lines of force from the main electrode for capacitance extend perpendicularly to the metal plate or the base over a wide range. Further, in the present embodiment, the measurement of the thickness has been described, but a physical quantity including a weight and the like in addition to the thickness can also be measured. That is, if a table of the change of the physical quantity and the capacitance value is prepared, the physical quantity can be calculated from the capacitance. Therefore, it goes without saying that “thickness” in this specification can be read as “thickness and weight”.

[0033]

According to the present invention, even if the moving metal plate is displaced up and down on the base, the thickness meter based on the capacitance and the distance meter based on the eddy current are integrated to form the metal plate. The thickness of the insulating film formed thereon can be accurately measured. According to the present invention, since the main electrode for capacitance and the core for eddy current are integrated, the measuring device can be reduced in size, and more accurate measurement can be performed than when both electrodes are provided separately.

[Brief description of the drawings]

FIG. 1A is a diagram for explaining a sensor unit for measuring a thickness in an embodiment of the present invention. (B) is an embodiment of the present invention, and is a block diagram for explaining an apparatus or method for measuring the thickness of an insulating film formed on a moving metal plate.

FIG. 2 is a specific detailed explanatory view of a sensor section in another embodiment of the main electrode for capacitance.

FIG. 3 is an overall schematic view of a main electrode for capacitance shown in FIG. 2;
FIG. 3 is a diagram in which a part of a sensor unit, an object to be measured, and a base are omitted.

FIG. 4 is a schematic explanatory view of a sensor section of a main electrode for capacitance in another embodiment, in which an object to be measured and a base are omitted.

FIG. 5 is a schematic diagram illustrating a conventional example for measuring the thickness of an insulating film formed on a moving metal plate.

FIG. 6 is a diagram for explaining a principle of measuring a distance between a sensor unit and a metal plate using an eddy current.

FIG. 7 is a diagram for explaining the principle of a thickness gauge in a capacitance system.

FIG. 8 is an explanatory diagram for measuring a thickness of a resin film formed on a moving metal plate by a measuring method in a conventional example.

FIG. 9 is an explanatory diagram for measuring a thickness of a wide resin film formed on a metal plate by a measuring method in a conventional example.

[Explanation of symbols]

 11 ... Sensor part 11 '... Recess part 11 "... Projection part 12 ... Base 13 ... Guard electrode 13' ... Recess part 13" ... Opening 14 ... Insulating member (fourth insulating member) 15: ground electrode 16: coil 17: insulating layer (insulating hollow bobbin) 18: concave portion 191, 192, 193: lead wire 21: metal plate 22: insulating Functional film 111 ・ ・ ・ Sensor unit 112 ・ ・ ・ Correction value setting unit 113 ・ ・ ・ Capacitance detection unit 114 ・ ・ ・ Calculation unit 115 ・ ・ ・ Database 116 ・ ・ ・ Display unit 172 ・ ・ ・1 insulating member 173 ... second insulating member 174 ... third insulating member 191,192,193 ... lead wire 211 ... sensor section 212 ... shield / capacitance main electrode 213 ...・ Cylindrical conductor

Claims (5)

(57) [Claims] An apparatus for measuring the thickness of an insulating film formed on a moving metal plate, comprising: a conductive member; and an eddy current coil wound around the conductive member. A sensor unit serving also as a main electrode for capacitance and a core for eddy current; a guard electrode provided on the same plane as the sensor unit and provided insulated from the sensor unit; and an insulating member provided on the guard electrode A plate-like ground electrode placed through the eddy current core, the displacement between the surface of the metal plate and the eddy current core is measured by the eddy current core, and the correction distance between the metal plate surface and the eddy current core is determined. A correction value setting unit to obtain, a capacitance detection unit that measures the capacitance between the surface of the metal plate and the capacitance main electrode by the capacitance main electrode, and The obtained value is increased by the correction value obtained from the correction value setting unit. A thickness calculator for calculating the thickness of the insulating film on the metal plate, comprising: a thickness calculator for calculating the thickness of the insulating film formed on the moving metal plate. 2. The apparatus for measuring the thickness of an insulating film formed on a moving metal plate according to claim 1, wherein the conductive member is made of an amorphous metal. 3. A sensor unit which also serves as a main electrode for capacitance and a core for eddy current provided with an eddy current coil wound around a projection formed by a recess formed in the conductor member. 3. The thickness measuring device for an insulating film formed on a moving metal plate according to claim 1 or 2, wherein 4. An apparatus for measuring the thickness of an insulating coating formed on a moving metal plate, comprising: an eddy current coil wound around an insulating hollow bobbin; A conductive member provided via the first insulating member; a shield / capacitance main electrode provided around the conductive member via the second insulating member; A guard electrode provided on the electrode via a third insulating member, a plate-like ground electrode placed on the guard electrode via a fourth insulating member, and a surface of the metal plate by the eddy current coil. A displacement value between the shield and the main electrode for shield and capacitance, and a correction value setting unit for obtaining a correction distance between the surface of the metal plate and the main electrode for shield and capacitance; and the main electrode for shield and capacitance. The surface of the metal plate and the shield And a capacitance detecting unit that measures the capacitance between the capacitance detecting unit and the value obtained from the capacitance detecting unit by the correction value obtained from the correction value setting unit. A thickness measuring unit for calculating a thickness, comprising: a thickness calculating unit configured to calculate a thickness of the insulating film formed on the moving metal plate. 5. A method for measuring the thickness of an insulating film formed on a moving metal plate by using the measuring device according to claim 1 or 2, wherein the eddy current core and the portion to be measured are provided. Displacement with the surface of the metal plate,
After measuring the capacitance between the capacitance main electrode and the surface of the metal plate, the capacitance was corrected by the displacement between the eddy current core and the surface of the metal plate, and the capacitance was corrected. A method for measuring the thickness of an insulating film formed on a moving metal plate, wherein the thickness is calculated from capacitance.