JP2019035707A - Gap measurement device and probe - Google Patents

Abstract

To provide a gap measurement device that stably and accurately measures target objects having a narrow gap at low cost and a probe therefor.SOLUTION: There is provided a gap measurement device for conductive target objects. A probe has a first electrode 4 and a third electrode 6a surrounding the first electrode 4 on one surface side, and has a second electrode 5 and fourth electrodes 7b, 7c surrounding the second electrode 5 on an opposite surface side. A measurement output unit 2 comprises: AC current generation means 20 which includes a sine wave generation circuit and applies an AC current to each electrode; impedance converters 13a, 13b for placing the third electrode 6a and fourth electrode 7b, 7c at a same potential, and placing the first electrode 4 and second electrode 5 at a same potential; and voltage measurement means 14a, 14b for measuring voltage on each electrode. The AC current generation means 20 includes a phase shift circuit 11 for outputting a phase shifted sine wave that has been shifted to the second electrode 5 and fourth electrodes 7b, 7c. The measurement output unit 2 calculates a gap distance between the target objects based on the voltage values output from the voltage measurement means 14a, 14b.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a gap measuring device and a measuring element thereof that can measure a gap between conductive objects to be opposed to each other in a non-contact manner.

  Conventionally, in order to measure the gap between objects, a plurality of metal plates with known thicknesses are sequentially inserted into the gap between objects to be measured, and the dimensions are measured by touching and removing the metal plates that have entered the gap. However, since the measuring element is a contact type using a metal plate, the object to be measured is scratched, and the measured value changes depending on the measurer. Therefore, a capacitance type measuring device that measures this without contact is known. It has become.

Japanese Patent Publication No.59-050882 International Publication No. 1993/024844

  The invention disclosed in Patent Document 1 is a capacitance-type measuring device, in which only the main electrode for measurement is arranged on the measuring element, and it is easily affected by noise or the like when actually used. , Shield is needed. And in patent document 2, what provided the shield in this is disclosed. The inventions of both Patent Document 1 and Patent Document 2 have a drawback that the capacitance cannot be measured accurately because the lines of electric force are curved at the end of the main electrode. Therefore, it is known that an electrode, a so-called guard electrode, is provided around the main electrode, and an AC power supply is applied in the same manner as the main electrode to measure the curvature of the electric lines of force at the end of the main electrode. ing.

  The problem is that the measurement becomes unstable due to the mutual interference of the applied AC current when the measuring element is made flat to measure the gap between the objects to be measured and the main electrode is arranged in the vicinity of the back and front surfaces of the measuring element. was there.

  In order to suppress the above-described mutual interference, if the lead lines are configured independently from the main electrode, the guard electrode, and the shield, for example, a printed wiring board having more than six layers is used, and a via hole is formed between the inner layers. There was a need, and there was a problem in terms of cost. In addition, the thickness of the measuring element increases due to the increase in the number of layers, and the minimum gap that can be measured increases, making it difficult to measure an object to be measured with a narrow gap.

  In view of such a problem, an object of the present invention is to provide a gap measuring device that can stably measure an object to be measured having a narrow gap and a measuring element thereof.

In order to achieve the above object, the gap measuring device according to claim 1
A gap measuring device comprising a flat-shaped measuring element inserted into a gap between conductive objects to be measured, and a measurement output unit for measuring the distance between the objects to be measured by connecting the measuring element,
On one side of the measuring element, a first electrode and a third electrode provided so as to surround and surround the first electrode are disposed,
On the opposite surface side of the probe, a second electrode and a fourth electrode provided so as to surround and surround the second electrode are disposed,
The measurement output section
An alternating current generating means for applying an alternating current based on the sine wave to the first electrode, the third electrode, the second electrode, and the fourth electrode, including a sine wave generating circuit for generating a sine wave;
Inserted between the third electrode and the fourth electrode and the alternating current generating means, the first electrode and the third electrode, and the second electrode and the fourth electrode are set to the same potential in an alternating manner. An impedance converter;
Voltage measuring means for measuring and outputting the voltage values of the third electrode and the fourth electrode, respectively;
With
AC current generation means
A phase shift circuit for outputting a phase-shifted sine wave with the phase of the sine wave shifted to the second electrode and the fourth electrode;
The measurement output section
Calculation is made based on each voltage value output from the voltage measuring means to measure the gap distance of the object to be measured.

In order to achieve the above object, the gap measuring device according to claim 2
The voltage measuring means is
A first multiplier for multiplying a voltage signal of the fourth electrode by a signal based on the sine wave extracted from the sine wave generation circuit;
A second multiplier for multiplying a voltage signal of the third electrode by a signal based on the phase-shifted sine wave extracted from the phase-shift circuit;
A low-pass filter that converts the outputs from the first multiplier and the second multiplier into DC signals, respectively.

In order to achieve the above object, the gap measuring device according to claim 3
The phase shift by the phase shift circuit is constituted by plus 90 degrees or minus 90 degrees.

In order to achieve the above object, the gap measuring device according to claim 4
A first electrode and a third electrode are provided having a first plane;
A second electrode and a fourth electrode are provided having a second plane;
The third electrode is provided so as to include a region obtained by projecting the second electrode onto the first plane,
The fourth electrode is configured to include a region obtained by projecting the first electrode onto the second plane.

In order to achieve the above object, the gap measuring device according to claim 5
The first electrode, the second electrode, the third electrode, and the fourth electrode are formed in a printed wiring pattern,
The first electrode and the third electrode are provided on the first layer which is the conductor surface layer of the probe,
A second electrode and a fourth electrode are provided on the second layer which is a conductor surface layer opposite to the first layer of the probe;
The first wiring drawn out from the first electrode and the second wiring drawn out from the second electrode are provided in an intermediate layer between the first layer and the second layer via a through hole, respectively. Configured.

In order to achieve the above object, the gap measuring device according to claim 6
In the measuring element, the first wiring of the intermediate layer is separated from the third wiring connected to the third electrode and is surrounded by the third wiring, and the third electrode of the first layer and the fourth electrode of the second layer Arranged to be sandwiched between
The second wiring of the intermediate layer is separated from the fourth wiring connected to the fourth electrode and is surrounded by the second wiring, and is sandwiched between the third electrode of the first layer and the fourth electrode of the second layer. Placed in
The third electrode of the first layer, the fourth electrode of the second layer, the third wiring of the intermediate layer, and the fourth wiring are separated by a fifth wiring that is electrically connected to the object to be measured. Each of which is surrounded.

In order to achieve the above object, the gap measuring device according to claim 7
The intermediate layer of the probe is composed of a single layer.

In order to achieve the above object, the gap measuring device according to claim 8
The first plane of the first electrode of the probe and the second plane of the second electrode are at least one of polyimide, polyetherketone, polyetheretherketone, polyetherketoneketone and polyetheretherketoneketone. It is configured to be covered with a dielectric including one.

In order to achieve the above object, the measuring element according to claim 9
A measuring element used by connecting to a measurement output unit of a gap measuring device for measuring a gap distance of a conductive object to be measured,
On one side of the measuring element, a first electrode and a third electrode provided so as to surround and surround the first electrode are disposed,
On the opposite surface side of the probe, a second electrode and a fourth electrode provided so as to surround and surround the second electrode are disposed,
The measurement output section
An alternating current generating means for applying an alternating current based on the sine wave to the first electrode, the third electrode, the second electrode, and the fourth electrode, including a sine wave generating circuit for generating a sine wave;
Inserted between the third electrode and the fourth electrode and the alternating current generating means, the first electrode and the third electrode, and the second electrode and the fourth electrode are set to the same potential in an alternating manner. An impedance converter;
Voltage measuring means for measuring and outputting the voltage values of the third electrode and the fourth electrode, respectively;
With
AC current generation means
A phase shift circuit for shifting the phase of the sine wave to the second electrode and the fourth electrode and outputting the phase shifted sine wave;
The measurement output section
Calculation is made based on each voltage value output from the voltage measuring means to measure the gap distance of the object to be measured.

In order to achieve the above object, the probe according to claim 10
The voltage measuring means is
A first multiplier for multiplying a voltage signal of the fourth electrode by a signal based on the sine wave extracted from the sine wave generation circuit;
A second multiplier for multiplying a voltage signal of the third electrode by a signal based on the phase-shifted sine wave extracted from the phase-shift circuit;
A low-pass filter that converts the outputs from the first multiplier and the second multiplier into DC signals, respectively.

In order to achieve the above object, the measuring element according to claim 11
The phase shift by the phase shift circuit is constituted by plus 90 degrees or minus 90 degrees.

In order to achieve the above object, the measuring element according to claim 12
A first electrode and a third electrode are provided having a first plane;
A second electrode and a fourth electrode are provided having a second plane;
The third electrode is provided so as to include a region obtained by projecting the second electrode onto the first plane,
The fourth electrode is configured to include a region obtained by projecting the first electrode onto the second plane.

In order to achieve the above object, the measuring element according to claim 13
The first electrode, the second electrode, the third electrode, and the fourth electrode are formed in a printed wiring pattern,
The first electrode and the third electrode are provided on the first layer which is the conductor surface layer of the probe,
A second electrode and a fourth electrode are provided on the second layer which is a conductor surface layer opposite to the first layer of the probe;
The first wiring drawn out from the first electrode and the second wiring drawn out from the second electrode are provided in an intermediate layer between the first layer and the second layer via a through hole, respectively. Configured.

In order to achieve the above object, the measuring element according to claim 14
The first wiring of the intermediate layer is separated from the third wiring connected to the third electrode and is surrounded by the first wiring, and is sandwiched between the third electrode of the first layer and the fourth electrode of the second layer. Placed in
The second wiring of the intermediate layer is separated from the fourth wiring connected to the fourth electrode and is surrounded by the second wiring, and is sandwiched between the third electrode of the first layer and the fourth electrode of the second layer. Placed in
The third electrode of the first layer, the fourth electrode of the second layer, the third wiring of the intermediate layer, and the fourth wiring are separated by a fifth wiring that is electrically connected to the object to be measured. Each of which is surrounded.

In order to achieve the above object, the measuring element according to claim 15
The intermediate layer is composed of a single layer.

In order to achieve the above object, the measuring element according to claim 16 provides:
The first plane of the first electrode and the second plane of the second electrode include at least one of polyimide, polyetherketone, polyetheretherketone, polyetherketoneketone, and polyetheretherketoneketone. It is configured to be covered with a dielectric.

  According to the gap measuring device of the first aspect of the present invention, an alternating current whose phase is shifted is applied to the second electrode for measurement facing in the opposite direction with respect to the first electrode for measurement. By measuring the voltage between the electrode and the ground, it is possible to provide a gap measuring device that reduces the mutual interference and enables the object to be measured to be measured without contact.

  According to the gap measuring device of the invention described in claim 2, in addition to the above effect, the voltage measuring means is provided with a multiplier to multiply the voltage of the guard electrode on the original sine wave side by the shifted square wave, Provided is a gap measuring device that eliminates the influence of mutual interference and makes it possible to measure an object to be measured with high accuracy in a non-contact manner by multiplying the voltage of the guard electrode on the shifted side by the original square wave. be able to.

  According to the gap measuring apparatus of the third aspect of the present invention, in addition to the above effect, by setting the phase of the alternating current on the shifting side to plus 90 degrees or minus 90 degrees, the influence of mutual interference is reduced to the minimum. It is possible to provide a gap measuring device that can measure a measurement object with higher accuracy in a non-contact manner.

  According to the gap measuring device of the invention described in claim 4, in addition to the above effect, the fourth electrode and the third electrode are opposed to the inner surface of the first electrode and the second electrode, respectively. Therefore, the state of the electric lines of force at the respective ends of the first electrode and the second electrode can be improved, and a highly accurate gap measuring device can be provided.

  According to the gap measuring device of the invention described in claim 5, in addition to the above effects, it can be realized by a manufacturing method of a printed wiring board, and an inexpensive measuring element can be provided. In addition, since the first wiring drawn out from the first electrode and the second wiring drawn out from the second electrode are provided in the intermediate layer through the through holes, noise entering from the outside Resistance from can be increased.

  According to the gap measuring apparatus of the invention described in claim 6, in addition to the above effect, the first wiring of the intermediate layer is surrounded by the third wiring connected to the third electrode, and the surface direction is the first direction. The third wiring is sandwiched between the third electrode and the fourth electrode, and is surrounded by a ground fifth wiring connected to the object to be measured. The second wiring of the intermediate layer is surrounded by a fourth wiring connected to the fourth electrode, the surface direction is sandwiched between the third electrode and the fourth electrode, and the fourth wiring is further connected. The periphery is surrounded by the fifth ground wiring connected to the object to be measured. Therefore, it is possible to eliminate the influence of the electrostatic capacitance related to the measurement that occurs inside the probe, and to increase the resistance from noise. That is, the electrostatic capacitance between the first electrode and the ground and the second electrode and the ground on the inner side of the measuring element is arranged to be zero.

  According to the gap measuring device of the invention described in claim 7, in addition to the above effect, the intermediate layer may be a single layer, so that the measuring element becomes a total of three layers and is thin, and the number of layers is small. Therefore, cost reduction can be achieved. In addition, it is possible to provide a gap measuring device that can measure an object to be measured having a narrow gap by using a thin measuring element having a small number of layers.

  According to the gap measuring apparatus of the invention described in claim 8, in addition to the above effects, each electrode plane is easily covered with a predetermined thickness by a manufacturing method such as film lamination or spin coating, and each electrode plane is protected. Can do.

It is a plane schematic diagram at the time of connecting the measurement output part and measuring element in the clearance gap measuring device concerning the embodiment of the present invention. It is a mimetic diagram at the time of measuring the crevice of a measured object using the measurement output part and measuring element in the crevice measuring device concerning the embodiment of the present invention. It is the perspective block diagram which showed the front-end | tip part of the measuring element of the clearance gap measuring apparatus which concerns on embodiment of this invention for every layer. It is the figure which combined and showed the block diagram of the AA cross-section schematic diagram of the measuring element in the clearance gap measuring apparatus which concerns on embodiment of this invention, and the electrical circuit of a measurement output part. It is the figure which combined and showed the schematic diagram of the measuring element in the clearance gap measuring apparatus which concerns on embodiment of this invention, and the electric circuit figure of a measurement output part. It is a schematic diagram which shows the structure of the electrostatic capacitance between the clearance gap measuring apparatus which concerns on embodiment of this invention, and a to-be-measured object. It is the figure which showed the waveform of each signal which concerns on the measurement by the clearance gap measuring apparatus which concerns on embodiment of this invention. It is the figure which showed the waveform of each signal which concerns on the measurement by the clearance gap measuring apparatus which concerns on embodiment of this invention.

  Hereinafter, a gap measuring device according to an embodiment of the present invention will be described in detail based on the drawings. FIG. 1 shows a gap measuring device 1 according to an embodiment of the present invention, and is a schematic plan view when a measuring element 3 inserted into a gap of a measured object is connected to a measurement output unit 2.

  The gap measuring device 1 is composed of a box-shaped measurement output unit 2 and a flat probe 3.

  The measurement output unit 2 has a box shape that can be carried by a measurer in his / her hand. The measurement output unit 2 has a power switch, a button for performing a measurement operation, a display unit for displaying measurement values, and the like on the surface. Is provided with a power source and an electrical circuit and electrical components described later.

  The measuring element 3 has a structure of a flat printed wiring board, and has a contact terminal part that can be inserted and removed to engage with a connector provided in the measurement output part 2. Therefore, the gap measuring device 1 can perform measurement by exchanging the measuring element 3 when the measuring element 3 is damaged or deteriorated.

  FIG. 2 is a diagram schematically illustrating the measurement of the gap of the object to be measured using the measurement output unit 2 and the probe 3 in the gap measurement apparatus 1 according to the embodiment of the present invention.

  The DUT 100a and the DUT 100b are conductive metals, and the gap distance is D. The device under test 100 a and the device under test 100 b are connected to the measurement output unit 2 through the ground line 8. The device under test 100a and the device under test 100b may be configured integrally. The device under test 100a and the device under test 100b may be configured separately, but at that time, they are electrically connected to each other via the ground line 8.

  The actual measurement of the gap between the device under test 100a and the device under test 100b is performed by inserting the probe 3 into the space between the device under test 100a and the device under test 100b with the ground line 8 connected to the measurement output unit 2. This can be done by pressing the measurement instruction button of the measurement output unit 2.

  FIG. 3 is a perspective configuration diagram showing the tip portion of the probe 3 of the gap measuring device 1 according to the embodiment of the present invention for each layer. In this embodiment, the probe 3 is a printed wiring board having a conductive pattern of three layers of copper foil. Each conductor pattern of the printed wiring pattern is formed by etching a laminated copper foil, and can be manufactured by a normal method for manufacturing a multilayer laminated printed wiring board.

  FIG. 3 (L1) shows the conductor pattern in the first layer which is the conductor surface layer on one side of the measuring element 3. A circular first electrode 4 forming a main electrode is disposed at the center of the tip of the probe 3, and an upper surface side of the first electrode 4, for example, one side surface facing the object to be measured 100a in FIG. This is the first plane 31.

  A third electrode 6a that forms a guard electrode is provided in a ring-shaped pattern that is spaced apart from and surrounds the vicinity of the first electrode 4, and the upper surface side of the third electrode 6a, that is, the device under test 100a. The surface facing the same is also the same first plane 31. Since the first electrode 4 and the third electrode 6a are formed of the same conductor foil, they have the same plane. Further, a fifth wiring 27 is provided in a ring-like pattern that is spaced apart from and surrounds the vicinity of the third electrode 6 a and is connected to the DUTs 100 a and 100 b and the ground line 8.

  Further, a third electrode 6b is provided in a ring-shaped pattern that is spaced apart from and surrounds the fifth wiring 27. Further, a fifth wiring 27 is again provided in a ring shape and a wiring pattern that surrounds and surrounds the third electrode 6b.

  In addition, the third electrodes 6 a and 6 b have an extending portion configured by wiring so as to be connected to the measurement output portion 2 from the tip portion of the probe 3.

  FIG. 3 (M) shows a conductor pattern in an intermediate layer which is an inner layer of the probe 3, and this intermediate layer is a single layer. The first wiring 23 is connected from the first electrode 4 via the non-through hole 21 a, and the first wiring 23 is provided so as to be connected to the measurement output unit 2.

  The third wiring 25 is provided so as to surround the first wiring 23. The third wiring 25 is connected to the third electrode 6a of the first layer through the through through hole 22a. Further, a fifth wiring 27 is provided in the vicinity of the third wiring 25 so as to surround the periphery, and the fifth wiring 27 has the same position and the same shape as the fifth wiring 27 in the first layer.

  FIG. 3 (L2) shows the conductor pattern in the second layer which is the conductor surface layer on the opposite side of the probe 3. The fourth electrode 7a is provided with an arc having the same dimension as the outer periphery of the third electrode 6a in the first layer as the outer periphery. The lower surface side of the fourth electrode 7 a, that is, the opposite surface facing the object to be measured 100 b is a second plane 32 parallel to the first plane 31. Therefore, the fourth electrode 7 a is provided so as to include a region obtained by projecting the first electrode 4 of the first layer onto the second plane 32.

  The shape of the fourth electrode 7a is a shape having a circle and a wiring extending portion drawn from the circle. The through-hole 22a is connected to the third electrode 6a in the first layer and the second wiring 24 in the intermediate layer.

  A fifth wiring 27 is provided so as to surround the fourth electrode 7a. The fifth wiring 27 has the same shape at the same position as the fifth wiring 27 of the first layer, and is connected by the through-through hole 22c.

  Further, a fourth electrode 7b is provided so as to surround and surround the fifth wiring 27 in the vicinity. The fourth electrode 7b is connected to the fourth electrode 7c at both ends of the arc, and has an arc-shaped hollow portion in the radial direction. A through-through hole 22b is provided near the end of the arc of the fourth electrode 7c, and is connected to the third electrode 6b of the first layer.

  And the 2nd electrode 5 which is a main electrode is provided so that it may be inserted | pinched between the 4th electrode 7b and the 4th electrode 7c. In the present embodiment, the second electrode 5 has an arc-shaped pattern and the area thereof is set to be equal to the area of the first electrode 4 in the first layer, but the present invention is not limited to this. By making the area of the first electrode 4 and the area of the second electrode 5 the same, the calculation is simplified as described later. The third electrode 6b of the first layer is provided so as to include a region obtained by projecting the second electrode 5 onto the first plane 31.

  Returning to FIG. 3 (M), the second layer 24 is connected to the second electrode 5 of the second layer via the non-through hole 21b. Yes. The fourth wiring 26 is disposed so as to surround the vicinity of the second wiring 24. The fourth wiring 26 is connected to the third electrode 6b in the first layer and the fourth electrode 7c in the second layer by the through through hole 22b. The fourth wiring 26 is also surrounded by a fifth wiring 27.

  On the other hand, both sides of the first wiring 23 of the intermediate layer are covered with the extending portion of the third electrode 6a of the first layer and the extending portion of the fourth electrode 7a of the second layer. Further, the second wiring 24 of the intermediate layer is covered on both sides by the extended portion of the third electrode 6b of the first layer and the extended portions of the fourth electrodes 7b and 7c of the second layer.

  4 is a schematic diagram of the AA cross section of the probe 3 in FIG. 1 of the gap measuring device 1 according to the embodiment of the present invention.

  This is not necessary when the object to be measured 100a and the object to be measured 100b facing each other are electrically connected with an integral metal, but if the object to be measured 100a and the object to be measured 100b are separate members. In some cases, both are made conductive by the ground line 8. Then, the wiring in which the ground line 8 is drawn from either the device under test 100 a or the device under test 100 b is connected to the fifth wiring 27 of the measuring element 3 through the ground of the measurement output unit 2.

  A dielectric 9 is provided on the first plane 31 side and the second plane 32 side of the measuring element 3, and a protective layer is formed by covering the first electrode 4, the second electrode 5, and the like. Form and protect from the external environment. The dielectric 9 is, for example, at least one of polyimide, polyether ketone, polyether ether ketone, polyether ketone ketone, and polyether ether ketone ketone. The dielectric 9 is formed by a technique such as laminating a film or applying a target liquid by spin coating. Therefore, the thickness of the dielectric 9 can be defined very accurately by the process of forming the protective layer, and the calculation described later is facilitated.

  The distance between the first plane 31 and the second plane 32 is t, which is the sum of the thicknesses of the first electrode 4, the second electrode 5, and the intermediate layer.

  FIG. 5 is a diagram showing a schematic diagram of a probe in the gap measuring apparatus according to the embodiment of the present invention and a block diagram of an electric circuit of a measurement output unit.

  The sine wave generation circuit 10 has one end connected to the ground inside the measurement output unit 2 and has an oscillator to generate a sine wave. The output of the sine wave generating circuit 10 is converted to a constant current by a constant current generating circuit 12 a and connected to the first electrode 4. Then, the output of the sine wave generation circuit 10 is branched in the middle, becomes a phase-shifted sine wave through the phase shift circuit 11, and is further made constant by the constant current conversion circuit 12b and connected to the second electrode 5. . The phase shift circuit 11 shifts the phase of the sine wave output from the sine wave generation circuit 10 to the plus side or the minus side.

  The output from the constant current circuit 12a is branched in the middle, one is connected to the first electrode 4 and the other is connected to the third electrode 6a and the fourth electrode 7a via the impedance converter 13a. Yes. Further, the output from the constant current circuit 12b is branched in the middle, one is connected to the second electrode 5, and the other is connected to the fourth electrodes 7b and 7c and the third electrode 6b via the impedance converter 13b. It is connected to. The first electrode 4 and the third electrode 6a, and the second electrode 5 and the fourth electrodes 7b and 7c have the same potential in terms of alternating current by the impedance converter 13a and the impedance converter 13b. No current flows from 4 to the third electrode 6a and from the second electrode 5 to the fourth electrodes 7b and 7c, and between the first electrode 4 and the third electrode 6a and between the second electrode 5 and the fourth electrode 7a. The influence of the capacitance between the electrodes 7b and 7c can be canceled. In the present invention, the impedance converter 13a and the impedance converter 13b use buffer amplifiers.

  The ground inside the measurement output unit 2 connected to the ground line 8 is connected to the third wiring 25 in the probe 3.

  The voltage measuring means 14a is connected to the voltage output of the impedance converter 13a, and measures and outputs the voltage of the third electrode 6a. The voltage measuring unit 14b is connected to the output of the impedance converter 13b, and measures and outputs the voltages of the fourth electrodes 7b and 7c. The voltage measuring means 14a and 14b both measure the voltage on the guard electrode side. As described above, the AC potential of the main electrode and the guard electrode is the same, and the guard electrode side is more than the main electrode. It has a low impedance circuit configuration, is not easily affected by disturbances, and can be measured stably.

The voltage measuring means 14a includes a band pass filter 15a, an amplifier 16a, a first multiplier 17a, and a low pass filter 19a arranged in series. The band pass filter 15a is connected to the voltage output of the impedance converter 13a to remove noise, and then the amplifier 16a amplifies the voltage signal. Further, the first multiplier 17a takes out the amplified voltage signal and the phase-shifted sine wave Ref ₂ phase-shifted by the phase-shift circuit 11, and converts it into a square wave by the square-wave converter 18a. , And output. The low-pass filter 19a outputs the voltage value as a DC signal. The square wave converter 18a is provided for facilitating the calculation described later, and is not always necessary.

The voltage measuring unit 14b includes a band pass filter 15b, an amplifier 16b, a second multiplier 17b, and a low pass filter 19b arranged in series. The band pass filter 15b is connected to the voltage output of the impedance converter 13b to remove noise, and then the amplifier 16b amplifies the voltage signal. Further, the second multiplier 17b takes out the amplified voltage signal and the original sine wave Ref ₁ that has not been phase-shifted by the phase-shift circuit 11, and converted it into a square wave by the square-wave converter 18b. , And output. The voltage value is output as a DC signal by the low-pass filter 19b. The square wave converter 18b is also provided for facilitating the calculation described later, and is not always necessary.

  Here, the following can be understood from FIG. 3, FIG. 4 and FIG. The first electrode 4 is surrounded by the third electrode 6a in the same layer, and at the same time, the first electrode 4 is surrounded by the fourth electrode 7a on the inner side of the probe 3. On the other hand, the periphery of the second electrode 5 is surrounded by the fourth electrodes 7b and 7c in the same layer, and at the same time, the inner side of the measuring element 3 is surrounded by the third electrode 6b. The third electrodes 6a, 6b and the fourth electrodes 7a, 7b, 7c are so-called guard electrodes, and serve to adjust the electric lines of force at the ends of the first electrode 4 and the second electrode 5 that are measurement electrodes. Is made. Further, a third wiring 25 connected to the ground line 8 is further disposed around the guard electrode, and serves to reduce the influence of noise.

  The first wiring 23 drawn out from the first electrode 4 is surrounded by the third wiring 25 in the same layer, and the surface direction is the extension of the third electrode 6a of the first layer and the second layer of the second wiring. 4 is surrounded by the extending portion of the electrode 7a. The second wiring 24 drawn out from the second electrode 5 has a fourth wiring 26 around the same layer in the same layer, and the extending portion of the third electrode 6b in the first layer and the fourth layer in the second layer in the surface direction. Of the electrodes 7b and 7c. Therefore, a guard electrode is provided so that the capacitance inside the probe does not affect the capacitance in the gap between the probe 3 and the measured objects 100a and 100b.

  With this configuration, an alternating current is generated by the alternating current generating means 20 and applied to the first electrode 4 and the second electrode 5 to obtain voltage value outputs from the voltage measuring means 14a and the voltage measuring means 14b. The gap distance D between the device under test 100a and the device under test 100b can be measured by calculating using the calculation formula described below.

  FIG. 6 is a schematic diagram showing the configuration of the capacitance between the gap measuring device and the object to be measured according to the embodiment of the present invention.

The component of the capacitance C ₁ between the first electrode 4 and the object 100a to be measured is the capacitance C _S1 of the dielectric 9 having the thickness t _{1 on} the surface of the measuring element 3 on the first plane 31 side, This is a combined capacitance in series with a capacitance C ₀₁ having a distance d ₁ between the dielectric 9 and the device under test 100a. On the other hand, inside the probe 3, the capacitance C _i1 of the first electrode 4 and the third wiring 25 connected to the ground line 8 is configured to be zero. Similarly, the component of the capacitance C ₂ between the second electrode 5 and the DUT 100 b is the capacitance C of the dielectric 9 having a thickness t _{2 on} the surface of the measuring element 3 on the second plane 32 side. and _S2, a series composite capacitance of the capacitance _{C 02} of the distance _{d 2} between the dielectric 9 DUT 100b. On the other hand, the capacitance C _{i2 of} the second electrode 5 and the third wiring 25 connected to the ground line 8 is similarly set to zero inside the measuring element 3.

また第２の電極５と被測定物１００ｂ間の静電容量Ｃ_２は次の式で表すことができる。

Therefore, the capacitance C ₁ between the first electrode 4 and the DUT 100a can be expressed by the following equation.

The capacitance C ₂ between the second electrode 5 and the measured object 100b can be expressed by the following equation.

When the area on the first plane 31 of the first electrode 4 is A, and the relative dielectric constant of the dielectric 9 having the thickness t ₁ and the thickness t _{2 on} the surface of the measuring element 3 is εs (known), the second The area of the electrode 5 on the second plane 32 is also A, and each capacitance can be expressed by the following equation. Note that ε ₀ is a vacuum dielectric constant.

  FIG. 7 is a diagram showing waveforms of signals related to measurement by the gap measuring device according to the embodiment of the present invention. The details about the ability to measure the gap of the object to be measured using the gap measuring device of the present invention will be described below.

FIG. 7A shows the sine wave Ref ₁ output from the sine wave generation circuit 10. On the other hand, FIG. 7B shows a phase-shifted sine wave Ref ₂ output by the phase shift circuit 11 with a phase of the sine wave Ref ₁ output from the sine wave generation circuit 10 delayed by 90 degrees.

Thus FIG. 7 (c) is a waveform of the current I ₁ output from the constant current circuit 12a. On the other hand shown in FIG. 7 (g) is a waveform of the current I ₂ which is output from the constant current circuit 12b, and has a 90-degree delayed phase relative to I _1. Note the absolute value and the constant-Ryuka as the absolute value of I ₂ is equal circuit 12a and the constant current circuit 12b and I ₁ in the present embodiment is set.

式（７）に式（３）と式（５）を代入して整理すると、電圧ｖ_１は式（８）及び図７（ｄ）で表される

The capacitance components described above, the third voltage v ₁ of the electrode 6a side is delayed 90 degrees with respect to the current I _1, the voltage v ₁ which is input to the voltage measuring means 14a is expressed by Equation (7) . Note that ω is an angular frequency.

By substituting Equation (3) and Equation (5) into Equation (7), the voltage v ₁ is expressed by Equation (8) and FIG. 7 (d).

Next, the output v _r2 from the square wave converter 18a that is input to the first multiplier 17a of the voltage measuring means 14a is expressed by Equation (9) and FIG. 7 (e).

Therefore, the output V ₁ as a result of multiplying v ₁ and v _r2 by the first multiplier 17a is expressed by Expression (10) and FIG. 7 (f).

そして上述のようにＩ_１との絶対値とＩ_２の絶対値は等しくなるように設定していることから式（１１）は式（１２）と表される。

On the other hand, the fourth electrode 7b, the voltage _{v 2} of 7c side is delayed 180 degrees in total with respect to the current _{I 1} so delayed 90 degrees with respect to the current _{I 2.} Therefore, the voltage _{v 2} which is input to the voltage measuring means 14b is represented by the formula (11) and FIG. 7 (h).

Since the absolute value of I ₁ and the absolute value of I ₂ are set to be equal as described above, equation (11) is expressed as equation (12).

On the other hand, the output v _r1 from the square wave converter 18b inputted to the second multiplier 17b of the voltage measuring means 14b is expressed by the equation (13) and FIG. 7 (i).

The output V ₂ as a result of multiplying v ₂ and v _r1 by the second multiplier 17b is expressed by equation (14) and FIG. 7 (j).

The phase shift circuit 11 in FIG. 8 shows the timing of each signal according to the measurement in the case where Advances the I ₂ 90 degrees. The method of calculation is the same as described above, resulting in V ₁ was negative (see FIG. 8 (f)), V ₂ is output to the positive side (see FIG. 8 (j)). Therefore, it can be understood that the phase shift may be plus 90 degrees or minus 90 degrees.

Next, V ₁ and V ₂ are outputted as direct current signals Va and Vb by low-pass filters 19a and 19b, respectively, which become voltage value outputs from the voltage measuring means 14a and 14b.

なお隙間距離Ｄが既知の被測定物を予め用意して較正を行えば、ｔ、ｔ_１、ｔ_２が既知でない場合であっても測定は可能となる。 Here, since t, t ₁ , and t ₂ are known, the gap distance D can be obtained by Expression (15).

If a measurement object with a known gap distance D is prepared in advance and calibrated, measurement is possible even when t, t ₁ and t ₂ are not known.

According to the embodiment of the present invention, a phase-shifted alternating current is applied to the measurement electrode disposed on the lower surface with respect to the measurement electrode disposed on the upper surface of the probe. Even if the component of the voltage v ₁ of the third electrode 6a enters the second multiplier 17b (see FIG. 7 (k)), the output v _r1 from the square wave converter 18b is used. Since multiplication is performed (see FIG. 7 (l)), the output component is in a state as shown in FIG. 7 (m), and the positive component and the negative component appear in the same manner, which can be canceled out.

  Further, since the measurement main electrode is provided in a shape surrounded by the guard electrode and the ground, it is possible to measure the gap between the objects to be measured with a measuring element having a small number of layers. By reducing the number of measuring elements, the cost can be reduced, and a thin measuring element can be realized, so that an object to be measured with a narrow gap can be measured. For example, using a 12.5 μm thick polyimide film for the printed circuit board base and protective dielectric, and forming through holes with 12 μm thick conductive copper foil, a probe with a total thickness of less than 0.15 mm is realized. it can.

  As mentioned above, although this invention was demonstrated based on preferable embodiment, this invention is not limited to embodiment mentioned above, A various change is possible in the range which does not deviate from the summary.

  As an application example of the present invention, it can be applied to a gap measuring device for measuring gaps of metal members of industrial machines.

1: Gap measuring device 2: Measurement output unit 3: Measuring element 4: First electrode (main electrode)
5: Second electrode (main electrode)
6a, 6b: third electrode (guard electrode)
7a, 7b, 7c: fourth electrode (guard electrode)
8: Ground line 9: Dielectric 10: Sine wave generation circuit 11: Phase shift circuit 12a, 12b: Constant current circuit 13a, 13b: Impedance converter (buffer amplifier)
14a, 14b: Voltage measuring means 15a, 15b: Band pass filters 16a, 16b: Amplifier 17a: First multiplier 17b: Second multipliers 18a, 18b: Square wave converters 19a, 19b: Low pass filter 20: AC Current generating means 21a, 21b: Non-through-holes 22a, 22b, 22c: Through-through holes 23: First wiring (main line)
24: Second wiring (main line)
25: Third wiring (guard line)
26: Fourth wiring (guard line)
27: Fifth wiring (ground line)
31: First plane 32: Second plane 100a, 100b: Object to be measured

Claims (16)

A gap measuring device comprising a flat-shaped measuring element inserted into a gap between conductive objects to be measured, and a measurement output unit that connects the measuring elements to measure the distance of the gap of the object to be measured. And
On one side of the measuring element, a first electrode and a third electrode provided so as to be separated and surrounded in the vicinity of the first electrode are arranged,
On the opposite surface side of the measuring element, a second electrode and a fourth electrode provided so as to be spaced apart in the vicinity of the second electrode are arranged,
The measurement output unit is
An alternating current that includes a sine wave generation circuit for generating a sine wave and applies an alternating current based on the sine wave to the first electrode, the third electrode, the second electrode, and the fourth electrode; Current generating means;
The first electrode and the third electrode, the second electrode and the fourth electrode are inserted between the third electrode and the fourth electrode and the alternating current generating means, respectively. An impedance converter that has the same potential alternatingly;
Voltage measuring means for measuring and outputting the voltage values of the third electrode and the fourth electrode, respectively;
With
The alternating current generating means includes
A phase shift circuit for outputting a phase-shifted sine wave obtained by shifting the phase of the sine wave to the second electrode and the fourth electrode;
The measurement output unit is
A gap measuring device, wherein the gap distance of the object to be measured is measured by calculation based on the voltage values output from the voltage measuring means. The voltage measuring means includes
A first multiplier that multiplies the voltage signal of the fourth electrode by a signal based on the sine wave extracted from the sine wave generation circuit;
A second multiplier for multiplying the voltage signal of the third electrode by a signal based on the phase-shifted sine wave extracted from the phase-shift circuit;
The gap measuring device according to claim 1, further comprising: a low-pass filter that converts outputs from the first multiplier and the second multiplier into DC signals.   The gap measuring device according to claim 1 or 2, wherein a phase shift by the phase shift circuit is plus 90 degrees or minus 90 degrees. The first electrode and the third electrode are provided with a first plane;
The second electrode and the fourth electrode are provided with a second plane;
The third electrode is provided so as to include a region obtained by projecting the second electrode onto the first plane,
The fourth electrode is provided so as to include a region obtained by projecting the first electrode onto the second plane;
The gap measuring device according to any one of claims 1 to 3, wherein The first electrode, the second electrode, the third electrode, and the fourth electrode are formed in a printed wiring pattern;
The first electrode and the third electrode are provided in a first layer which is a conductor surface layer of the probe;
The second electrode and the fourth electrode are provided in a second layer which is a conductor surface layer opposite to the first layer of the probe;
An intermediate in which the first wiring drawn out from the first electrode and the second wiring drawn out from the second electrode are respectively intermediate between the first layer and the second layer via a through hole The gap measuring device according to claim 4, wherein the gap measuring device is provided in a layer. In the measuring element, the first wiring of the intermediate layer is separated from the third wiring connected to the third electrode and is surrounded by the third wiring, and the third electrode and the first wiring of the first layer Arranged to be sandwiched between two layers of the fourth electrode,
The second wiring of the intermediate layer is separated from the fourth wiring connected to the fourth electrode and is surrounded by the second wiring, and the third electrode of the first layer and the second wiring of the second layer Arranged so as to be sandwiched between four electrodes,
The third electrode of the first layer, the fourth electrode of the second layer, the third wiring of the intermediate layer, and the fourth wiring are electrically connected to the object to be measured. The gap measuring device according to claim 5, wherein the gap is surrounded by a fifth wiring so as to be separated from each other.   The gap measuring apparatus according to claim 5, wherein the intermediate layer of the measuring element is a single layer.   The first plane of the first electrode and the second plane of the second electrode of the probe are polyimide, polyetherketone, polyetheretherketone, polyetherketoneketone, and polyether. The gap measuring device according to any one of claims 4 to 7, wherein the gap measuring device is covered with a dielectric containing at least one of ether ketone ketone. A measuring element used by connecting to a measurement output unit of a gap measuring device for measuring a gap distance of a conductive object to be measured,
On one side of the measuring element, a first electrode and a third electrode provided so as to be separated and surrounded in the vicinity of the first electrode are arranged,
On the opposite surface side of the measuring element, a second electrode and a fourth electrode provided so as to be spaced apart in the vicinity of the second electrode are arranged,
The measurement output unit is
An alternating current that includes a sine wave generation circuit for generating a sine wave and applies an alternating current based on the sine wave to the first electrode, the third electrode, the second electrode, and the fourth electrode; Current generating means;
The first electrode and the third electrode, the second electrode and the fourth electrode are inserted between the third electrode and the fourth electrode and the alternating current generating means, respectively. An impedance converter that has the same potential alternatingly;
Voltage measuring means for measuring and outputting the voltage values of the third electrode and the fourth electrode, respectively;
With
The alternating current generating means includes
A phase shift circuit that shifts the phase of the sine wave to the second electrode and the fourth electrode and outputs the phase shifted sine wave;
The measurement output unit is
A measuring element that calculates based on each voltage value output from each of the voltage measuring means and measures a gap distance of the object to be measured. The voltage measuring means includes
A first multiplier that multiplies the voltage signal of the fourth electrode by a signal based on the sine wave extracted from the sine wave generation circuit;
A second multiplier for multiplying the voltage signal of the third electrode by a signal based on the phase-shifted sine wave extracted from the phase-shift circuit;
The measuring element according to claim 9, further comprising: a low-pass filter that converts outputs from the first multiplier and the second multiplier into DC signals.   The measuring element according to claim 9 or 10, wherein a phase shift by the phase shift circuit is plus 90 degrees or minus 90 degrees. The first electrode and the third electrode are provided with a first plane;
The second electrode and the fourth electrode are provided with a second plane;
The third electrode is provided so as to include a region obtained by projecting the second electrode onto the first plane,
The fourth electrode is provided so as to include a region obtained by projecting the first electrode onto the second plane;
The measuring element according to any one of claims 9 to 11, wherein: The first electrode, the second electrode, the third electrode, and the fourth electrode are formed in a printed wiring pattern;
The first electrode and the third electrode are provided in a first layer which is a conductor surface layer of the probe;
The second electrode and the fourth electrode are provided in a second layer which is a conductor surface layer opposite to the first layer of the probe;
An intermediate in which the first wiring drawn out from the first electrode and the second wiring drawn out from the second electrode are respectively intermediate between the first layer and the second layer via a through hole The measuring element according to claim 12, wherein the measuring element is provided in a layer. The first wiring of the intermediate layer is spaced apart from and surrounded by a third wiring connected to the third electrode, and the third electrode of the first layer and the first wiring of the second layer Arranged so as to be sandwiched between four electrodes,
The second wiring of the intermediate layer is separated from the fourth wiring connected to the fourth electrode and is surrounded by the second wiring, and the third electrode of the first layer and the second wiring of the second layer Arranged so as to be sandwiched between four electrodes,
The third electrode of the first layer, the fourth electrode of the second layer, the third wiring of the intermediate layer, and the fourth wiring are electrically connected to the object to be measured. The measuring element according to claim 13, wherein the measuring element is surrounded by a fifth wiring so as to be separated from each other.   The measuring element according to claim 13 or 14, wherein the intermediate layer is a single layer.   The first plane of the first electrode and the second plane of the second electrode are at least polyimide, polyetherketone, polyetheretherketone, polyetherketoneketone, and polyetheretherketoneketone. The measuring element according to claim 12, wherein the measuring element is coated with a dielectric including one.

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