JP2015059845A - Capacitive sensor and method of measuring elastic deformation amount, elastic deformation distribution, or surface pressure distribution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitive sensor which is capable of measuring capacitance with high accuracy by removing crosstalk capacitance.SOLUTION: The capacitive sensor includes: a dielectric layer comprising an elastomer composition; a front side electrode layer which is laminated on the front surface side of the dielectric layer and comprises a plurality of front side conductive parts arranged like stripes; a rear side electrode layer which is laminated on the rear surface side of the dielectric layer and comprises a plurality of rear side conductive parts arranged like stripes so as to be substantially orthogonal to the plurality of front side conductive parts in plan view; and measuring means which measures capacitances of detection parts formed in respective intersection areas between the plurality of front side conductive parts and the plurality of rear side conductive parts in plan view. The plurality of front side conductive parts and the plurality of rear side conductive parts include carbon nano tubes. The capacitive sensor further includes control means which connects selected one of the front side conductive parts and selected one of the rear side conductive parts to the measuring means so as to apply a fixed voltage to them and connects the other front side conductive parts and/or the other rear side conductive parts to the ground.

Description

  The present invention relates to a capacitance type sensor, and a method for measuring an amount of stretching deformation strain, a stretching deformation strain distribution or a surface pressure distribution.

The capacitance type sensor sheet can detect the uneven shape of the measurement object from the capacitance change between the pair of electrode layers, and can be used for sensors such as a surface pressure distribution sensor and a strain gauge. Generally, the capacitance (capacitance) in a capacitance type sensor is expressed by the following equation (1).
C = ε ₀ · ε _r · S / d (1)
Here, C is a capacitance, ε ₀ is a permittivity of free space, ε _r is a relative permittivity of a dielectric layer, S is an electrode layer area, and d is an interelectrode distance.

  Conventionally, by using an electrostatic capacitance type sensor sheet in which electrode pairs are arranged in a matrix, the external force position is measured by measuring the electrostatic capacitance that changes with the deformation of the dielectric layer when an external force is applied. In addition, a capacitance type sensor that measures the size is known (see, for example, JP-A-2012-225727).

  In such a capacitance type sensor, the position and magnitude of the external force are determined by measuring the capacitance at each position (detection unit) where electrode pairs arranged in a matrix form intersect.

  However, when using a capacitive sensor sheet in which electrode pairs are arranged in a matrix, the electrostatic capacitance is added due to crosstalk between adjacent detectors due to the matrix structure, and the initial state (no deformation) In the state), the capacitance of the detection unit becomes larger than the theoretical value. As the number of electrodes increases, the added capacitance increases. In such a case, a minute change in capacitance cannot be measured, and there is a disadvantage that the detection sensitivity of the capacitance type sensor becomes insufficient. In addition, when the capacitance is added due to crosstalk between adjacent detection units as described above, the capacitance changes even in an undeformed region when a part of the capacitance type sensor sheet is deformed. Is measured. As a result, there is a disadvantage that the measurement accuracy of the capacitive sensor becomes insufficient.

JP 2012-225727 A

  The present invention has been made based on the above circumstances, and provides a capacitive sensor with high detection sensitivity and high measurement accuracy, and a method for measuring the amount of expansion / contraction deformation strain, distribution of expansion / contraction deformation strain or surface pressure distribution. The purpose is to do.

  The invention made in order to solve the above problems includes a dielectric layer made of an elastomer composition, a front side electrode layer made up of a plurality of front side conductive parts stacked on the surface side of the dielectric layer and arranged in a stripe shape, A back-side electrode layer comprising a plurality of back-side conductive portions that are stacked on the back side of the dielectric layer and arranged in stripes so as to be substantially orthogonal to the plurality of front-side conductive portions in plan view; A capacitance type sensor having a measuring means for measuring a capacitance of a detection unit formed in each crossing region of a front side conductive unit and a plurality of back side conductive units, wherein each of the conductive units includes a carbon nanotube. Including one selected front side conductive part and one selected back side conductive part connected to the measuring means so that a constant voltage is applied, and the remaining front side conductive part and / or the remaining back side Conductive part is gran A capacitive sensor comprising a control means for connecting.

  The capacitance type sensor detects the capacitance of the detection unit formed in the intersection region of the selected one front-side conductive part and the selected one back-side conductive part. Matrix structure of the front side electrode layer and the back side electrode layer by grounding all the front side conductive parts other than the front side conductive part and all the back side conductive parts other than the selected one back side conductive part. The crosstalk capacitance generated due to the above can be removed, and the capacitance of the detection portion between the selected one front-side conductive portion and the selected one back-side conductive portion can be measured with high accuracy. In addition, since each of the conductive portions includes carbon nanotubes, each of the electrode layers exhibits excellent followability with respect to deformation of the dielectric layer. It is possible to follow the deformation and movement of objects. In the capacitance type sensor, the dielectric layer, the front electrode layer, and the back electrode layer greatly expand and contract in the plane direction, and the capacitance changes with the change in area. Measurement can be performed with high accuracy, and as a result, deformation and movement of a measurement object having a large extension and flexibility can be measured.

  The average fiber diameter of the carbon nanotube is preferably 0.5 nm or more and 30 nm or less. When the average fiber diameter of the carbon nanotube is within this range, the front electrode layer and the back electrode layer exhibit high followability to the deformation of the dielectric layer.

  Each of the conductive parts preferably contains 30% by mass or more of carbon nanotubes having an average fiber length of 100 μm or more and 700 μm or less with respect to the total solid components. When the front side conductive part and the back side conductive part contain the long carbon nanotubes having such a length above the lower limit amount, the front side electrode layer and the back side electrode layer have higher followability to the deformation of the dielectric layer. Demonstrate.

  The average thickness of the front side conductive part and the back side conductive part is preferably 0.1 μm or more and 10 μm or less. When the average thicknesses of the front-side conductive portion and the back-side conductive portion are within this range, the front-side electrode layer and the back-side electrode layer exhibit higher conductivity and higher followability to deformation of the dielectric layer.

  The elastomer composition preferably contains urethane rubber as a main component. When the dielectric layer is made of an elastomer composition containing urethane rubber as a main component, the dielectric layer is excellent in resistance to repeated deformation, and durability of the capacitance type sensor is improved.

  The elongation ratio in the uniaxial direction of the dielectric layer is preferably 30% or more. By setting the expansion rate in the uniaxial direction of the dielectric layer to be equal to or greater than the above lower limit, the capacitance type sensor can effectively exhibit excellent followability with respect to deformation and operation of a flexible measurement object. it can.

  The capacitance type sensor is preferably used for measuring the amount of expansion / contraction deformation strain, the expansion / contraction deformation strain distribution, or the surface pressure distribution based on the measurement result of the measuring means. Since the capacitance type sensor can accurately measure each capacitance in all the detection units, the measurement result can be used to increase the amount of expansion / contraction deformation strain, the distribution of expansion / contraction deformation strain or the surface pressure distribution of the sensor sheet. It can be measured with high accuracy.

  The method for measuring the amount of stretching deformation strain, the strain deformation distribution or the surface pressure distribution according to the present invention comprises a dielectric layer comprising an elastomer composition and a plurality of front sides laminated on the surface side of the dielectric layer and arranged in stripes. A front-side electrode layer composed of a conductive portion and a back-side electrode composed of a plurality of back-side conductive portions stacked on the back side of the dielectric layer and arranged in stripes so as to be substantially orthogonal to the plurality of front-side conductive portions in plan view Stretching deformation amount, stretching deformation strain distribution or surface pressure using a sensor sheet having a layer and a detection portion formed in each crossing region of the plurality of front-side conductive portions and the plurality of back-side conductive portions in plan view A distribution measuring method, wherein each of the conductive parts includes carbon nanotubes, and the selected one front-side conductive part and the selected one back-side conductive part are applied to the measuring unit so that a constant voltage is applied. Connect and The front side conductive part and / or the remaining back side conductive part are connected to the ground and the capacitance of the detection part in the crossing region is measured, and all the combinations of the front side conductive part and the back side conductive part are sequentially detected. The above measurement process is repeated by switching the parts.

  According to the measurement method of the stretch deformation strain amount, the stretch deformation strain distribution or the surface pressure distribution, it corresponds to all the front side conductive parts other than the front side conductive part corresponding to the detection part for measuring the capacitance, and the detection part. By connecting at least one of all the back side conductive parts other than the back side conductive part to the ground, the crosstalk capacitance caused by the matrix structure of the front side electrode layer and the back side electrode layer can be removed. The electrostatic capacitance of the detection part between the front side conductive part and the selected one back side conductive part can be measured with high accuracy. In the measurement method of the stretch deformation strain amount, the stretch deformation strain distribution or the surface pressure distribution, the above measurement is repeated for all the combinations of the front conductive portion and the back conductive portion. It is possible to measure, and based on these measurement results, the amount of stretch deformation strain, the stretch deformation strain distribution, the surface pressure distribution, etc. can be measured with high accuracy.

  Note that “ground connection” means that the potential of the front-side conductive portion or the back-side conductive portion is equal to the ground level of the measuring means.

  As described above, the capacitance-type sensor of the present invention and the method for measuring the amount of stretch deformation strain, the strain deformation distribution or the surface pressure distribution remove the crosstalk capacitance and increase the capacitance with high accuracy. Since it can be measured, the amount of stretch deformation strain, the stretch deformation strain distribution, the surface pressure distribution, etc. can be measured with high sensitivity and high accuracy.

It is the typical permeation | transmission figure which looked at the capacitive type sensor which concerns on one Embodiment of this invention from the upper surface. It is typical sectional drawing of the AA direction of the sensor sheet | seat of FIG. It is a schematic diagram for demonstrating the measurement operation | movement of the electrostatic capacitance type sensor of FIG. It is a schematic diagram for demonstrating the measurement operation | movement of the capacitive type sensor of embodiment different from FIG. It is a schematic diagram of the film-forming apparatus of the dielectric layer and protective layer of the sensor sheet | seat of FIG. It is a schematic diagram for demonstrating the connection structure of the capacitive type sensor of embodiment different from FIG. 6 is a schematic diagram of wiring of a capacitive sensor of Comparative Example 1. FIG. (A) is a graph which shows the electrostatic capacitance distribution measured in Example 1, (b) is a graph which shows the electrostatic capacitance distribution measured in Example 2, (c) is Comparative Example 1. It is a graph which shows the electrostatic capacitance distribution measured by. (A) is a graph showing the capacitance measured for each measurement frequency in Example 1, (b) is a graph showing the capacitance measured for each measurement frequency in Example 2, (C) is a graph which shows the measured electrostatic capacitance for every measurement frequency in the comparative example 1. FIG. (A) It is the photograph which image | photographed the deformed sensor sheet | seat from upper direction, (b) It is the photograph which image | photographed the deformed sensor sheet | seat from the side. (A) is a graph which shows the electrostatic capacitance distribution measured using the sensor sheet deform | transformed in Example 1, (b) is the electrostatic measured using the sensor sheet deform | transformed in Example 2. It is a graph which shows a capacity | capacitance distribution, (c) is a graph which shows the electrostatic capacitance distribution measured using the sensor sheet | seat deform | transformed in the comparative example 1. FIG. (A) is a graph which shows a capacitance change distribution when the sensor sheet deformed in Example 1 is used, and (b) is a static graph when the sensor sheet deformed in Example 2 is used. It is a graph which shows an electrostatic capacitance change distribution, (c) is a graph which shows an electrostatic capacitance change distribution when the sensor sheet deform | transformed in the comparative example 1 is used.

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

[Capacitance type sensor]
As shown in FIGS. 1 and 2, the capacitive sensor 1 includes a dielectric layer 3 made of an elastomer composition, and a plurality of front sides that are laminated on the surface side of the dielectric layer 3 and arranged in stripes. A plurality of conductive layers 01A to 16A are stacked on the back side of the dielectric layer 3 and arranged in stripes so as to be substantially orthogonal to the plurality of conductive surfaces 01A to 16A in plan view. The back side electrode layer 5 composed of the back side conductive parts 01B to 16B, and the detection parts C0101 to C1616 formed in the intersecting regions of the plurality of front side conductive parts 01A to 16A and the plurality of back side conductive parts 01B to 16B in plan view. And measuring means 6 for measuring the electrostatic capacity. The capacitance type sensor 1 has a constant voltage applied to one front side conductive part selected from the plurality of front side conductive parts 01A to 16A and one back side conductive part selected from the plurality of back side conductive parts 01B to 16B. Is connected to the measuring means 6 so that is applied, and at least one of the remaining front side conductive part other than the selected front side conductive part and the remaining back side conductive part other than the selected back side conductive part is grounded A control means 7 is provided which is connected and causes the measurement means 6 to measure the capacitance of the detection part formed in the intersecting region of the selected front-side conductive part and back-side conductive part. The capacitance type sensor 1 is laminated so as to cover the front side electrode layer 4 on the surface side of the dielectric layer 3 and the back side electrode layer 5 on the back side of the dielectric layer 3. The back side protective layer 9 is further provided.

  Since the dielectric layer 3, the front electrode layer 4, and the back electrode layer 5 constituting the sensor sheet 2 of the capacitance type sensor 1 have elasticity, the sensor sheet 2 mainly expands and contracts in the planar direction. The capacitance changes as the areas of the front electrode layer 4 and the back electrode layer 5 change due to the expansion and contraction. The capacitance type sensor 1 measures the amount of strain in each detection unit from the change in capacitance, and measures the amount of stretch deformation strain, the stretch deformation strain distribution, the surface pressure distribution, and the like with high accuracy. Therefore, the capacitance type sensor 1 can measure the deformation and operation of the measurement object having a large extension and flexibility.

<Sensor sheet>
The sensor sheet 2 includes a sheet-like dielectric layer 3, a front-side electrode layer 4 composed of front-side conductive portions 01 A to 16 A of a belt-like body laminated on the surface side of the dielectric layer 3, front-side wirings 01 a to 16 a, The back electrode layer 5 which consists of the back side electroconductive parts 01B-16B of the strip | belt shaped body laminated | stacked on the back surface side of the dielectric layer 3, and back side wiring 01b-16b are provided. The portions where the front conductive portion and the back conductive portion intersect in plan view are detection units C0101 to C1616. In the detection unit code “CXXX”, the upper two digits “XX” correspond to the front conductive parts 01A to 16A, and the lower two digits “ΔΔ” indicate the back conductive parts. It corresponds to 01B-16B. Further, the sensor sheet 2 includes a front side switching circuit 10 to which the front side wirings 01a to 16a are connected, and a back side switching circuit 11 to which the back side wirings 01b to 16b are connected. The sheet-like dielectric layer 3 may be formed by laminating a plurality of thin films made of the same elastomer composition. In that case, other layers other than the dielectric layer made of the elastomer composition are interposed between these thin films. Is not placed. In addition, the front side electrode layer 4 or the back side electrode layer 5 and the dielectric layer 3 may be laminated | stacked through the adhesive bond layer, respectively.

  The average thickness, width and length of the sensor sheet 2 can be appropriately changed depending on the application of the sensor sheet 2 used.

<Dielectric layer>
The dielectric layer 3 is an elastically deformable layer. The dielectric layer 3 has a sheet shape and has a rectangular shape in plan view with the sides in the X direction and the Y direction. This dielectric layer 3 is formed uniformly by an elastomer composition.

  The lower limit of the average thickness of the dielectric layer 3 is preferably 10 μm, and more preferably 30 μm. The upper limit of the average thickness of the dielectric layer 3 is preferably 1,000 μm, and more preferably 200 μm. If the average thickness of the dielectric layer 3 is less than the above lower limit, it is difficult to process an elastomer layer with high film thickness accuracy, and sufficient detection distribution accuracy may not be ensured. Moreover, when the average thickness of the dielectric layer 3 exceeds the above upper limit, not only the capacitance decreases and the detection sensitivity decreases, but also the sensor sheet 2 becomes too thick and the followability to the measurement object may be impaired. .

  Moreover, as a minimum of the dielectric constant at normal temperature of the dielectric layer 3, 2 is preferable and 5 is more preferable. If the relative dielectric constant of the dielectric layer 3 is less than the above lower limit, the capacitance becomes small, and there is a possibility that sufficient sensitivity cannot be obtained when used as a sensor.

  Furthermore, the lower limit of the Young's modulus of the dielectric layer 3 is preferably 0.01 MPa, and more preferably 0.1 MPa. The upper limit of the Young's modulus of the dielectric layer 3 is preferably 5 MPa, and more preferably 1 MPa. When the Young's modulus is less than the above lower limit, the flexibility of the dielectric layer 3 becomes too high, processing is difficult, and sufficient measurement accuracy may not be obtained. On the other hand, when the Young's modulus exceeds the above upper limit, the flexibility of the dielectric layer 3 becomes too low, and the deformation operation of the sensor sheet is hindered when the deformation load on the sensor sheet is small, and the measurement result for the measurement purpose. May not be suitable.

  The lower limit of the uniaxial elongation rate of the dielectric layer 3 is preferably 30%, more preferably 50%, and even more preferably 100%. By setting the expansion rate in the uniaxial direction of the dielectric layer 3 to be equal to or higher than the above lower limit, the capacitance type sensor 1 effectively exhibits excellent followability with respect to deformation and operation of a flexible measurement object. be able to. In addition, although the upper limit of the expansion rate of the uniaxial direction of the dielectric layer 3 is not specifically limited, For example, it is 300%.

(Elastomer composition)
The elastomer composition constituting the dielectric layer 3 has an elastomer as a main component. Here, the “main component” is a component having the largest content among the components constituting the elastomer composition, for example, a component having a content of 50% by mass or more. Examples of the elastomer include natural rubber, isoprene rubber, nitrile rubber (NBR), ethylene propylene rubber (EPDM), styrene / butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), silicone rubber, and fluorine rubber. Acrylic rubber, hydrogenated nitrile rubber, urethane rubber and the like can be used. The elastomer constituting the dielectric layer 3 is preferably silicone rubber or urethane rubber having high elongation, excellent resistance to repeated deformation, and low permanent distortion. Urethane rubber is preferable because permanent deformation is small even when deformation is applied to the sensor sheet 2. If the permanent set is small, the initial capacitance hardly changes even if it is used repeatedly (for example, even if the expansion / contraction deformation with 100% elongation is repeated 1000 times), and the measurement accuracy is excellent as a capacitive sensor sheet. Can be maintained over a period of time. Further, the urethane rubber is excellent in adhesion to the carbon nanotubes which are conductive materials of the front electrode layer 4 and the back electrode layer 5.

  The elastomer composition for forming the dielectric layer 3 can be selected according to the measurement object and the measurement purpose, and can be improved in composition. In addition to the elastomer, the elastomer composition may contain additives such as a crosslinking agent, a plasticizer, a chain extender, a vulcanization accelerator, a catalyst, an anti-aging agent, an antioxidant, and a colorant.

  Moreover, the said elastomer composition can contain dielectric fillers, such as a barium titanate, besides the said elastomer. By containing the dielectric filler, the capacitance can be increased and the detection sensitivity can be increased.

<Front electrode layer>
The front-side electrode layer 4 is composed of a plurality of front-side conductive parts 01A to 16A arranged in a stripe shape (parallel), and is laminated on the surface side of the dielectric layer 3.

(Front conductive part)
Each of the front side conductive parts 01A to 16A has a band shape, and a total of 16 pieces are laminated on the surface of the dielectric layer 3 as shown in FIG. The front-side conductive parts 01A to 16A each extend in the X direction (left-right direction in FIG. 1). The front-side conductive portions 01A to 16A are respectively arranged so as to be substantially parallel to each other at a predetermined interval in the Y direction (vertical direction in FIG. 1). Front side connection portions 01A1 to 16A1 are arranged at the left ends of the front side conductive portions 01A to 16A in FIG.

  The front side conductive portions 01A to 16A each include a carbon nanotube. Further, the front conductive portions 01A to 16A may include a connecting material such as an elastomer in addition to the carbon nanotubes. By including such a binder material, it is possible to improve the adhesive strength between the electrode layer and the dielectric layer 3, improve the film strength of the electrode layer, etc., and at the time of coating the coating liquid containing carbon nanotubes Contributes to ensuring environmental safety (toxicity of carbon nanotubes and asbestos-like problems). However, it is preferable that the content of the binder material with respect to the total solid components of the electrode layer is small. By reducing the content of the connecting material, the change in electrical resistance with respect to repetitive deformation is small and the durability is excellent, and inhibition of deformation of the dielectric layer 3 can be suppressed.

  As the carbon nanotube, for example, a single-walled carbon nanotube or a multi-walled carbon nanotube can be used. Of these, single-walled carbon nanotubes having a smaller diameter and a larger aspect ratio are preferred. The lower limit of the average fiber length of the carbon nanotube is preferably 100 μm, more preferably 150 μm, and further preferably 200 μm. Moreover, as an upper limit of the average fiber length of the said carbon nanotube, 700 micrometers is preferable, 600 micrometers is more preferable, and 500 micrometers is further more preferable. The aspect ratio of the carbon nanotube is preferably 1,000 or more, more preferably 10,000 or more, and particularly preferably 30,000 or more. By using such ultra-long carbon nanotubes, the front side conductive portions 01A to 16A can exhibit excellent stretchability and can improve the followability to deformation of the dielectric layer 3.

  By using long carbon nanotubes as the material for forming the conductive part, the electrode layer composed of the stripe-shaped conductive part exhibits excellent stretchability, and the electrode layer is resistant to deformation of the dielectric layer accompanying the expansion and contraction of the sensor sheet. Followability can be improved. In addition, a conductive part including a long carbon nanotube has excellent long-term reliability because there is little variation in electrical resistance when it is repeatedly deformed. The reason for this is considered to be that long carbon nanotubes tend to expand and contract themselves, and as a result, the conductive path is not easily cut when the electrode layer expands following the dielectric layer. Further, when an electrode layer is formed using a conductive composition containing carbon nanotubes, the conductivity of the electrode layer is manifested by the carbon nanotubes contacting each other (forming an electrical contact). Here, when long carbon nanotubes are used, conductivity is ensured with a smaller number of electrical contacts than when short carbon nanotubes are used, and in addition to other carbon nanotubes in one carbon nanotube. Since the number of electrical contacts increases, a higher-dimensional electrical network is formed. Thus, it is considered that an electrode layer having excellent long-term reliability can be formed by using long carbon nanotubes to reduce fluctuations in electrical resistance.

  The lower limit of the average fiber diameter of the carbon nanotube is preferably 0.5 nm and more preferably 1 nm. Moreover, as an upper limit of the average fiber diameter of the said carbon nanotube, 30 nm is preferable and 20 nm is more preferable. When the average fiber diameter of the carbon nanotubes is within this range, the carbon nanotubes expand like springs when deformed, and exhibit high followability, so that the front electrode layer 4 and the back electrode layer 5 are High followability with respect to deformation of the dielectric layer 3 is exhibited. Single-walled carbon nanotubes are preferable in that they have a small average fiber diameter (the average fiber diameter is about 0.5 to 4 nm depending on the production method) and are highly flexible. On the other hand, since the multi-wall carbon nanotube has a large average fiber diameter and is rigid, a multi-wall carbon nanotube having a smaller average fiber diameter (for example, an average fiber diameter of 30 nm or less) is preferable.

  Examples of the elastomer material included as the binder material include natural rubber, isoprene rubber, nitrile rubber (NBR), ethylene propylene rubber (EPDM), styrene-butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), Silicone rubber, fluorine rubber, acrylic rubber, hydrogenated nitrile rubber, urethane rubber and the like can be mentioned. These may be used alone or in combination of two or more.

  As the above-mentioned connecting material, raw rubber (in a state where natural rubber and synthetic rubber are not vulcanized) is also preferable. By using a material having relatively weak elasticity in this way, the followability of the front conductive portions 01A to 16A with respect to the deformation of the dielectric layer 3 can be enhanced.

  Moreover, the front side conductive parts 01A to 16A may contain various additives in addition to the carbon nanotube and the elastomer material. Examples of the additives include a dispersant for dispersing carbon nanotubes, a crosslinking agent for binders, a vulcanization accelerator, a vulcanization aid, an anti-aging agent, a plasticizer, a chain extender, an antioxidant, and a softening agent. Agents, coloring agents and the like. For the purpose of improving the conductivity of the electrode layer, a method using a low molecular material such as a charge transfer material or an ionic liquid as a dopant as a coating agent or additive may be considered. However, a high aspect ratio carbon nanotube is used for the electrode layer. Thus, sufficient conductivity can be ensured without special treatment. In addition, when the low molecular material is used, the dielectric layer 3 is reduced in the insulating property (volume resistance), which is considered to be caused by migration of the low molecular material to the elastomer of the dielectric layer 3 or the plasticizer in the elastomer of the dielectric layer 3. Reduction in the rate), loss of the dopant effect of the electrode layer, reduction in durability against repeated deformation of the sensor sheet 2, and reduction in reliability of the measurement value. Therefore, it is preferable not to include the low molecular weight material.

  The lower limit of the content of the carbon nanotubes in the front conductive parts 01A to 16A with respect to all solid components is preferably 51% by mass, more preferably 75% by mass, still more preferably 90% by mass, and particularly preferably 95% by mass. Further, it is most preferable that the carbon nanotube concentration is 100% by mass, and the front side conductive portions 01A to 16A are substantially made of only carbon nanotubes. Moreover, it is preferable that the front side conductive parts 01A to 16A have a configuration not including the elastomer material. Thus, by reducing the content other than the carbon nanotube which is a conductive material, it is possible to suppress a decrease in conductivity (increase in electric resistance) of the front side conductive portions 01A to 16A even when subjected to repeated deformation, and durability. It can be excellent in properties.

  Moreover, as a minimum of content with respect to all the solid components of the long carbon nanotube (For example, carbon nanotube with an average fiber length of 100 micrometers or more and 700 micrometers or less) in the front side conductive parts 01A-16A, 30 mass% is preferable, and 50 mass% is more. Preferably, 70 mass% is more preferable. When the front-side conductive portion contains the long carbon nanotube having a content equal to or higher than the lower limit, the front-side electrode layer exhibits high followability to the deformation of the dielectric layer 3. As long as the front-side conductive part contains long carbon nanotubes having a content of at least the above lower limit, short carbon nanotubes (average fiber length of less than 100 μm) may be mixed. By mixing short carbon nanotubes, the front electrode layer can be formed at low cost.

  Moreover, as a minimum of the average thickness of front side electroconductive part 01A-16A, 0.1 micrometer is preferable and 0.2 micrometer is more preferable. The upper limit of the average thickness of the front side conductive portions 01A to 16A is preferably 10 μm, and more preferably 5 μm. By setting the average thickness of the front side conductive portions 01A to 16A within the above range, the front side conductive portions 01A to 16A can exhibit excellent followability to the deformation of the dielectric layer 3. If the average thickness of the front side conductive parts 01A to 16A is less than the lower limit, the conductivity may be insufficient and the detection accuracy may be reduced. On the other hand, when the average thickness of the front side conductive portions 01A to 16A exceeds the upper limit, the sensor sheet becomes hard due to the reinforcing effect of the carbon nanotubes, the followability of the sensor sheet 2 to the measurement object is reduced, and the dielectric layer 3 is deformed. May interfere.

  The belt-like widths of the front-side conductive parts 01A to 16A are appropriately changed depending on the application, but the lower limit of the belt-like average width of the front-side conductive parts 01A to 16A is preferably 0.5 mm and more preferably 1 mm. Moreover, as an upper limit of the strip | belt-shaped average width | variety of front side electroconductive part 01A-16A, 30 mm is preferable and 20 mm is more preferable. If the belt-like average width of the front conductive portions 01A to 16A is less than the lower limit, the capacitance detected at the electrode facing portion decreases, so that the detection error may increase. Moreover, when the strip | belt-shaped average width | variety of front side conductive part 01A-16A exceeds the said upper limit, the space | interval of an electrode opposing part will become large and the spatial resolution of distortion distribution will become low. However, when the spatial resolution requirement is low, for example, in the case of a large sensor sheet (such as a bed size), it is useful to widen the band width of the front side conductive portion.

  In addition, the average distance between the front side conductive parts 01A to 16A arranged in a stripe shape (parallel) is appropriately changed depending on the application, but the lower limit of the average distance between adjacent front side conductive parts is preferably 0.5 mm. 1 mm is more preferable. Moreover, as an upper limit of the average space | interval of an adjacent front side electroconductive part, 10 mm is preferable and 5 mm is more preferable. If the average distance between adjacent front conductive portions is less than the lower limit, adjacent front conductive portions are likely to be in contact with each other, and it may be difficult to form the front conductive portions. In addition, when the average interval between adjacent front-side conductive portions exceeds the above upper limit, the area that cannot be detected increases, and the spatial resolution of the strain distribution decreases. However, in the case of a large sensor sheet or the like that requires low spatial resolution, the interval between adjacent front side conductive portions need not be made smaller than necessary.

  Further, the transparency (visible light transmittance) of the front electrode layer 4 laminated on the dielectric layer 3 is not particularly limited, and may be transparent or opaque.

  The dielectric layer 3 made of the elastomer composition can be easily formed as a transparent dielectric layer. By increasing the transparency of the front-side electrode layer 4 and the back-side electrode layer 5, the capacitive sensor is transparent as a whole. It can be a sheet. When transparency is required as the capacitance type sensor sheet, a transparent electrode layer (for example, a visible light (550 nm light) transmittance of 85% or more) may be formed.

  On the other hand, the transparency of the electrode layer does not affect the performance as a capacitive sensor sheet. Therefore, when transparency is not required, a sensor sheet can be manufactured easily and inexpensively by forming an opaque electrode layer. When forming a transparent electrode layer using, for example, a conductive composition containing carbon nanotubes, pretreatment such as advanced dispersion treatment and purification treatment is required for the carbon nanotubes, and the electrode layer formation process becomes complicated. Economic disadvantage.

  Moreover, it is preferable that the front side conductive parts 01A to 16A are formed by applying a coating solution containing carbon nanotubes. For example, it is preferable to apply a coating liquid containing carbon nanotubes directly on the dielectric layer 3 by spray coating or the like to form the front side conductive portions 01A to 16A. Thereby, adhesion between the front side conductive portions 01A to 16A and the dielectric layer 3 is improved, and delamination between the front side conductive portions 01A to 16A and the dielectric layer 3 is suppressed.

<Back side electrode layer>
The back-side electrode layer 5 is composed of a plurality of back-side conductive parts 01B to 16B arranged in a stripe shape (parallel), and is laminated on the back side of the dielectric layer 3.

(Back side conductive part)
The back side conductive parts 01 </ b> B to 16 </ b> B each have a band shape, and a total of 16 pieces are laminated on the back surface of the dielectric layer 3. The back side conductive parts 01B to 16B are arranged so as to be substantially orthogonal to the front side conductive parts 01A to 16A, respectively, in plan view. That is, the back side conductive portions 01B to 16B each extend in the Y direction. Further, the back side conductive portions 01B to 16B are spaced apart from each other at predetermined intervals in the X direction, and are arranged so as to be substantially parallel to each other. Back side connection parts 01B1 to 16B1 are arranged at upper ends in FIG. 1 of the back side conductive parts 01B to 16B, respectively.

  The configuration of the back-side conductive parts 01B to 16B is substantially the same as the above-described front-side conductive parts 01A to 16A, and thus description thereof is omitted here.

<Front side wiring>
The front side wirings 01a to 16a have a linear shape, and connect the front side connection parts 01A1 to 16A1 and the front side switching circuit 10, respectively. The material constituting the front side wirings 01a to 16a is not particularly limited, and a conventionally known material can be used, but the front side wirings 01a to 16a can be configured by having the same configuration as the above-described front side conductive parts 01A to 16A. 16a can be expanded and contracted. Thereby, since the deformation of the dielectric layer 3 is not hindered, the amount of distortion of the dielectric layer 3 is accurately detected. That is, it is preferable that the front side wirings 01a to 16a have a content ratio other than the carbon nanotube which is a conductive material, and more preferably does not include an elastomer material.

<Backside wiring>
The back side wirings 01b to 16b have a linear shape, and connect the back side connection parts 01B1 to 16B1 and the back side switching circuit 11, respectively. The materials constituting the front side wirings 01a to 16a are substantially the same as those of the front side wirings 01a to 16a, and thus the description thereof is omitted here.

  When stretchability is not required for the region where the wiring and the connection portion are formed in the sensor sheet 2, in this region, instead of the flexible elastomer composition used, a PET film, a PEN film, a polyimide A base film having low elasticity such as a film can be used. By using such a base film, it is possible to manufacture a portion where wiring and a connecting portion are formed by a conventionally known conductive material and a conventionally known manufacturing method. For example, a wiring film produced by a metal plating technique or a metal printing technique can be used.

<Detector>
As shown by hatching in FIG. 1, the detection units (pixels) C0101 to C1616 are formed at portions where the front conductive portions 01A to 16A and the back conductive portions 01B to 16B intersect in plan view. In the capacitance type sensor 1, a total of 256 detection units C0101 to C1616 (= 16 × 16) are formed, and the capacitance is measured at 256 locations. When 256 detection units are formed independently, the front side electrode and the back side electrode exist for each detection unit, so 512 wirings are required with 256 × 2 poles, as in this embodiment. By crossing the strip-shaped conductive portions, the required number of wirings can be 16 + 16 = 32. Therefore, the detection unit is efficiently arranged as described above. Then, the sensor sheet 2 having such a configuration is connected to the measuring unit 6 to be the capacitance type sensor 1 as described later, and the control unit 7 connects the 16 wirings to the front side switching circuit 10 and the back side. By switching with the switching circuit 11, the measuring means 6 measures the capacitance while switching the 256 detection units one by one. As a result, the capacitive sensor 1 can measure the strain amount and strain position of each detection unit, the surface pressure distribution, and the like. The detection units C0101 to C1616 are arranged in a matrix at substantially equal intervals in the X direction and the Y direction.

<Front side switching circuit>
The front side switching circuit 10 includes a plurality of switches that are connected to the front side wirings 01 a to 16 a and the measurement terminals of the measurement unit 6 and switch the front side wirings 01 a to 16 a connected to the measurement terminals of the measurement unit 6. Thereby, only one front side conductive part selected by the control means 7 among the front side conductive parts 01 </ b> A to 16 </ b> A is connected to the measurement terminal of the measurement means 6. Further, the front side switching circuit 10 can connect any front side wirings 01a to 16a to the ground terminal 12 by switching the switches.

<Back side switching circuit>
The back side switching circuit 11 includes a plurality of switches that are connected to the back side wirings 01 b to 16 b and the measurement terminal of the measurement unit 6 and switch the back side wirings 01 b to 16 b connected to the measurement terminal of the measurement unit 6. Thereby, only one back side conductive part selected by the control means 7 among the back side conductive parts 01B to 16B is connected to the measurement terminal of the measurement means 6. The back side switching circuit 11 can connect any back side wirings 01b to 16b to the ground terminal 12 by switching the switches.

<Front side protective layer 8 and back side protective layer 9>
As shown in FIG. 2, the sheet-like front side protective layer 8 is disposed on the surface side of the dielectric layer 3 so as to cover the dielectric layer 3, the front side conductive portions 01 </ b> A to 16 </ b> A, and the front side wirings 01 a to 16 a. The sheet-like back side protective layer 9 is disposed on the back side of the dielectric layer 3 so as to cover the dielectric layer 3, the back side conductive parts 01B to 16B, and the back side wirings 01b to 16b. By providing the front side protective layer 8 and the back side protective layer 9 in this way, the front side conductive parts 01A to 16A, the front side wirings 01a to 16a, the back side conductive parts 01B to 16B, the back side wirings 01b to 16b, and the outside of the sensor sheet 2 It is possible to suppress conduction with the member.

  The purpose of providing the front side protective layer 8 and the back side protective layer 9 is not limited to the protection of the electrode layer. For example, by forming a colored protective layer, it is possible to make the conductive portion, wiring, and the like invisible from the outside, and design is imparted by printing on the protective layer. In addition, for example, the object to be measured can be attached to the sensor sheet 2 by providing a layer having adhesiveness or tackiness on the surface of the front side protective layer 8 and the back side protective layer 9. For example, the surface of the protective layer can be a surface layer having a low coefficient of friction.

  The material of the front side protective layer 8 and the back side protective layer 9 is not particularly limited, and may be appropriately selected depending on the purpose of formation thereof. For example, the same material as the elastomer composition used for the dielectric layer 3 can be used. The front side protective layer 8 and the back side protective layer 9 are preferably formed so as to include substantially the same base polymer as that of the dielectric layer 3, whereby high adhesion to the dielectric layer 3 can be obtained. The front side protective layer 8 and the back side protective layer 9 may be laminated on the dielectric layer 3 via an adhesive.

<Measuring means>
The measuring means 6 includes a measuring circuit for measuring the capacitance between the measuring terminals of the measuring means 6 and a power supply circuit. This measurement terminal is connected to the front side switching circuit 10 and the back side switching circuit 11 of the sensor sheet 3. The measuring means 6 applies a voltage signal between the measurement terminals, so that the front side conductive part connected by the front side switching circuit 10 and the back side conductive part connected by the back side switching circuit 11 intersect in plan view. The capacitance of the detection unit formed in the region is measured. When the measuring unit 6 measures the capacitance of the detection unit, the remaining front-side conductive unit and back-side conductive unit that are not connected to the measurement terminal of the measuring unit 6 are connected to the ground via the front-side switching circuit 10 and the back-side switching circuit 11. It is connected to the terminal 12. The measuring means 6 is connected (grounded) to a ground terminal having the same potential as a ground terminal 12 described later.

  The method of measuring the electrostatic capacity in the measuring means 6 is not particularly limited, but an AC signal is passed by an LCR meter, the impedance at the AC signal is measured, and the electrostatic capacity is measured, and output by the impedance at the AC signal. A measurement method using a change in AC impedance due to a change in capacitance, such as a method of measuring capacitance by changing the voltage of a signal or a method of changing the oscillation frequency by a CR oscillation circuit, is preferable.

<Ground terminal>
The ground terminal 12 is connected to the front side switching circuit 10 and the back side switching circuit 11 of the sensor sheet 3. The electric potential of the conductive part connected to the ground terminal 12 becomes the ground level and is equal to the ground level of the measuring means 6.

<Control means>
The control means 7 controls the switching of the switch of the front side switching circuit 10 and the switching of the switch of the back side switching circuit 11, and controls the voltage application timing and the capacitance measurement timing of the measuring means 6. The control means 7 controls the front side switching circuit 10 so as to sequentially switch the front side conductive parts 01A to 16A connected to one measurement terminal of the measurement means 6, and the back side conductive part connected to the other measurement terminal of the measurement means 6 The back side switching circuit 11 is controlled to sequentially switch 01B to 16B, and the capacitance of each of the detection units C0101 to C1616 is sequentially measured by the measurement unit 6 so as to scan from the detection unit C0101 to the detection unit C1616. .

  Here, the operation of sequentially measuring the capacitances of the detection units C0101 to C1616 by the control means 7 will be described below.

  In FIG. 3, the schematic diagram for demonstrating the measurement operation | movement of the said capacitance-type sensor 1 is shown. In FIG. 3, only the front side conductive portions 03A to 05A and the back side conductive portions 05B to 07B are schematically shown for easy understanding of the measurement operation, and the other front side conductive portions 01A, 02A, 06A to 16A are shown. The back side conductive parts 01B to 04B and 08B to 16B are not shown.

  The front side switching circuit 10 includes switches 03A2 to 05A2 that switch the connection of the front side conductive parts 03A to 05A to either the ground terminal 12 or one of the measurement terminals of the measuring means 6. The back side switching circuit 11 has switches 05B2 to 07B2 for switching the connection of the back side conductive parts 05B to 07B to either the ground terminal 12 or the other measurement terminal of the measuring means 6. FIG. 3 shows a state in which the measurement terminal of the measurement unit 6 is connected to the front conductive unit 04A and the back conductive unit 06B by the control unit 7. At this time, the switch 04A2 is connected to one measurement terminal side of the measurement means 6, and the switch 06B2 is connected to the other measurement terminal side of the measurement means 6. Meanwhile, at this time, the remaining switches 03A2, 05A2, 05B2, and 07B2 are all connected to the ground terminal 12. Although not shown in FIG. 3, at this time, all the front side conductive parts 01A, 02A, 06A to 16A and the back side conductive parts 01B to 04B and 08B to 16B are connected to the front side conductive parts 03A and 05A and the back side conductive parts. Similarly to the parts 05B and 07B, it is connected to the ground terminal 12.

  In the connection state of FIG. 3, the measuring means 6 applies a voltage signal to the front conductive part 04A and the back conductive part 06B, and is formed in a region where the front conductive part 04A and the back conductive part 06B intersect in plan view. The capacitance of the detection unit C0406 is measured. At this time, since all the front side conductive parts and the back side conductive parts other than the front side conductive part 04A and the back side conductive part 06B are connected to the ground terminal 12, the measurement means 6 does not add capacitance due to crosstalk. It is possible to accurately measure the capacitance of the detection unit C0406.

  The control means 7 repeats the above-described operation for all 256 detection units C0101 to C1616. That is, the control means 7 connects only one front-side conductive part and one back-side conductive part corresponding to the detection part to be measured to the measurement terminal of the measuring means 6, and the remaining front-side conductive part and back-side conductive part are connected. The operation of controlling the front side switching circuit 10 and the back side switching circuit 11 so as to be connected to the ground terminal 12 is sequentially performed for all the detection units C0101 to C1616. As a result, the capacitance of each of the detection units C0101 to C1616 is sequentially measured by the measuring unit 6.

  In the above, the control means 7 controls so that all the front side conductive parts and the back side conductive parts other than one front side conductive part and one back side conductive part corresponding to the detection part to be measured are connected to the ground terminal 12. Although an example has been described, if only one of the plurality of front side conductive parts and back side conductive parts that are not measured is connected to the ground terminal 12, the other conductive part that is not measured is not connected to the ground terminal 12. However, the crosstalk capacitance is reduced, and the measuring means 6 can measure the capacitance of the detection unit to be measured with high accuracy. Capacitance measurement operation of each of the detection units C0101 to C1616 in the case where the control is performed by connecting only the non-measuring back side conductive part to the ground terminal 12 without connecting the non-measuring front side conducting part to the ground terminal 12. Is described below.

  FIG. 4 is a schematic diagram for explaining the measurement operation of the capacitance type sensor 1 in this case. The configuration of FIG. 4 differs from the configuration shown in FIG. 3 only in the configuration of the switch of the front side switching circuit 10. That is, the switches 03A2 to 05A2 of the front side switching circuit 10 in FIG. 3 switch the connection of the front side conductive parts 03A to 05A to either the ground terminal 12 or one of the measurement terminals of the measuring means 6, whereas the front side in FIG. The switches 03A3 to 05A3 of the switching circuit switch the connection of the front side conductive portions 03A to 05A to either one of the measurement terminal side of the measuring means 6 or not (open).

  FIG. 4 shows a state in which the measurement terminal of the measurement means 6 is connected to the front side conductive part 04A and the back side conductive part 06B by the control means 7. At this time, the switch 04A3 is connected to one measurement terminal of the measurement means 6, and the switch 06B2 is connected to the other measurement terminal of the measurement means 6. On the other hand, at this time, the remaining switches 05B2 and 07B2 other than the switch 06B2 of the back side switching circuit are all connected to the ground terminal 12, and the remaining switches 03A3 and 05A3 other than the switch 04A3 of the front side switching circuit are both opened. State. Although not shown in FIG. 4, at this time, all the other back side conductive parts 01B to 04B and 08B to 16B are connected to the ground terminal 12 similarly to the back side conductive parts 05B and 07B. The front side conductive parts 01A, 02A, 06A to 16A are in an open state without being electrically connected to the measuring means 6, similarly to the front side conductive parts 03A, 05A.

  In the connection state of FIG. 4, the measuring means 6 applies a voltage signal to the front side conductive part 04A and the back side conductive part 06B, and is formed in a region where the front side conductive part 04A and the back side conductive part 06B intersect in plan view. The capacitance of the detecting unit C0406 is measured. At this time, since all the back side conductive parts other than the back side conductive part 06B are connected to the ground terminal 12, the addition of the electrostatic capacity due to crosstalk is reduced, and the electrostatic capacity of the detection part C0406 is measured almost accurately. be able to.

  The control means 7 repeats the measurement by the measurement means 6 with a combination of all front side conductive parts and back side conductive parts. That is, the control unit 7 repeatedly performs the above-described operation for all 256 detection units C0101 to C1616. Specifically, the control means 7 connects only one front-side conductive part and one back-side conductive part corresponding to the detection part to be measured to the measurement terminal of the measuring means 6, and the remaining back-side conductive parts are grounded. The operation of controlling the front side switching circuit and the back side switching circuit so as to connect to the terminal 12 and open the remaining front side conductive parts is sequentially performed for all the detection units C0101 to C1616. As a result, the capacitance of each of the detection units C0101 to C1616 is sequentially measured by the measuring unit 6.

  FIG. 4 illustrates a configuration in which the control means 7 opens the remaining front side conductive parts other than the front side conductive parts corresponding to the detection part to be measured, and grounds only the back side conductive parts not to be measured. However, even if the control means 7 controls the back side conductive portion that is not the measurement target to be in an open state and only the front side conductive portion that is not the measurement target is connected to the ground, the capacitance due to the crosstalk can be similarly added. Thus, the measurement means 6 can accurately measure the capacitance of each detection unit.

[Measurement method of stretch deformation strain, stretch deformation distribution or surface pressure distribution]
The measuring method of the stretch deformation strain amount, the stretch deformation strain distribution or the surface pressure distribution is such that one selected front side conductive portion and one selected back side conductive portion are connected to the measuring means 6 and the remaining front side conductive portions. And / or the step of measuring the capacitance of the detection part in the crossing region by connecting the remaining back side conductive parts to the ground (measurement process), and all the front side conductive parts 01A to 16 and the back side conductive parts 01B to 16B The detection unit is sequentially switched with respect to the combination of the above, and the above measurement process is repeated to measure the amount of stretch deformation strain distribution, the stretch deformation strain distribution, or the surface pressure distribution.

  Hereinafter, as an example of a method for measuring the stretch deformation strain amount, the stretch deformation strain distribution, or the surface pressure distribution, an example using the above-described capacitance type sensor will be described. Here, an example in which all front side conductive parts and back side conductive parts other than one front side conductive part and one back side conductive part corresponding to the detection unit to be measured are grounded will be described.

<Measurement process>
In the measuring step, the measuring means 6 applies a voltage signal between the selected one front-side conductive part and the selected one back-side conductive part, and in a region where these front-side conductive part and back-side conductive part intersect in plan view. The capacitance of the formed detection unit is measured. For example, in the case shown in FIG. 3, the measuring terminal of the measuring means 6 is connected to one selected front-side conductive part 04A and one selected back-side conductive part 06B, and the measuring means 6 receives a voltage signal between these conductive parts. Is applied to measure the capacitance between these conductive parts (detection part C0406).

  In the measurement method of the amount of stretch deformation strain, the strain deformation distribution or the surface pressure distribution, the measurement process is repeated for all combinations of the front side conductive parts and the back side conductive parts. Specifically, in the case of FIG. 3, the control means 7 connects only one selected front side conductive part and one selected back side conductive part to the measurement terminal of the measurement means 6, and the remaining front side conductive part and back side conductive part. The switch of the front side switching circuit 10 and the switch of the back side switching circuit 11 are controlled so that the part is connected to the ground terminal 12, and the selected front side conductive part and back side conductive part are sequentially switched. Then, the capacitance between one front side conductive portion and one back side conductive portion that are sequentially selected is sequentially measured by the measuring means 6.

  For example, the control unit 7 first selects the back side conductive part to be connected to the other measurement terminal of the measurement unit 6 in a state where the front side conductive part 01A is connected to one measurement terminal of the measurement unit 6 as one front side conductive part to be selected. , 01B, 02B,..., 16B, sequentially switched to the front-side conductive portion 02A as one front-side conductive portion to be selected, and connected to one measurement terminal of the measuring means 6; Control is performed so that the back side conductive portion connected to the other measurement terminal is sequentially switched to 01B, 02B,..., 16B. Similarly, in the respective states where the control means 7 is connected to one measurement terminal of the measuring means 6 while sequentially switching one front side conductive part to be selected with the front side conductive parts 03A to 16A. The back side conductive part connected to the other measurement terminal of the measuring means 6 is controlled so as to be sequentially switched to 01B, 02B,..., 16B. By controlling the control means 7 in this way, the capacitances of all the detection units C0101, C0102,..., C1616 are sequentially measured so as to scan the detection units arranged in a matrix. . The control method by the control means 7 is an example, and the selection order of the front-side conductive portion and the back-side conductive portion may be any way, or there may be a front-side conductive portion or a back-side conductive portion that is not selected.

[Method for manufacturing sensor sheet]
The sensor sheet 2 used for the capacitance type sensor 1 can be manufactured by various methods, an example of which is shown below. The sensor sheet 2 includes, for example, a step of forming a dielectric layer and a protective layer (dielectric layer forming step), a step of preparing a coating liquid for forming an electrode layer (electrode layer forming coating liquid preparing step), a dielectric layer and a protective layer It can be manufactured by a step (lamination step) of forming an electrode layer while laminating the layers.

<Dielectric layer formation process>
In the dielectric layer forming step, the dielectric layer 3, the front side protective layer 8, and the back side protective layer 9 are formed separately. The dielectric layer 3, the front side protective layer 8, and the back side protective layer 9 can all be formed by molding a raw material composition containing an elastomer into a sheet shape.

  First, additives such as a crosslinking agent, a plasticizer, a chain extender, a vulcanization accelerator, a catalyst, an anti-aging agent, an antioxidant, a colorant, and a dielectric filler are added to the elastomer (or its raw material) as necessary. A blended raw material composition is prepared.

  The method for preparing the raw material composition and the method for forming the sheet material are not particularly limited, and conventionally known methods can be used. Specifically, when the elastomer is urethane rubber, for example, a polyol component, a plasticizer, and an antioxidant are weighed and stirred and mixed for a certain time under heating and reduced pressure to prepare a mixed solution. Next, after measuring the mixed liquid and adjusting the temperature, the catalyst is added and stirred with an agitator or the like. Then, a predetermined amount of isocyanate component is added, and after stirring with an agitator or the like, the mixed solution is immediately poured into the film forming apparatus shown in FIG. A roll-wrapped sheet having a predetermined thickness is obtained. Then, if necessary, a sheet-like material that becomes any one of the dielectric layer 3, the front side protective layer 8, and the back side protective layer 9 is produced by performing a crosslinking reaction (post-crosslinking) for a certain period of time in a furnace.

  In the film forming apparatus shown in FIG. 5 used in the dielectric layer forming step, the raw material composition 14 is made of polyethylene terephthalate (PET) continuously fed from a pair of rolls 13 and 13 ′ arranged apart from each other. Pour into the gap of the protective film 17. And it introduce | transduces in the heating apparatus 15, advancing hardening reaction (crosslinking reaction) in the state which hold | maintained the raw material composition 14 in the clearance gap. In the heating device 15, the raw material composition 14 is thermally cured while being held between the pair of protective films 17, thereby forming the sheet-like dielectric layer 16.

  Moreover, after preparing a raw material composition, you may form the said sheet-like material using general-purpose film-forming apparatuses and film-forming methods, such as various coating apparatuses, a bar coat, and a doctor blade. When the elastomer is a composition other than urethane rubber, an additive such as a crosslinking agent suitable for the composition may be added and a suitable molding method may be used.

<Coating solution preparation process for electrode layer formation>
In the electrode layer forming coating solution preparation step, an electrode layer forming coating solution containing a conductive material such as carbon nanotubes and a dispersion medium is prepared.

  Specifically, first, the conductive material is added to a dispersion medium such as toluene. At this time, you may add a binder component (or its raw material), a dispersing agent, other various additives, etc. as needed. Next, a coating liquid for forming an electrode layer is prepared by dispersing (or dissolving) each component including a conductive material in a dispersion medium using a wet disperser. Here, for example, an existing disperser such as an ultrasonic disperser, a jet mill, a bead mill, or a stirrer may be used for dispersion.

  In the electrode layer forming coating solution preparation step, the dispersion medium is not limited to toluene, and other examples include methyl isobutyl ketone (MIBK), alcohols, and water. These dispersion media may be used alone or in combination of two or more.

  When the conductive material is carbon nanotube, the lower limit of the carbon nanotube concentration in the electrode layer forming coating solution is preferably 0.01% by mass, and the upper limit of the carbon nanotube concentration is preferably 10% by mass. If the concentration of the carbon nanotubes is less than the lower limit, the concentration of the carbon nanotubes may be too thin, and it may be necessary to repeatedly apply the carbon nanotubes. On the other hand, if the concentration of the carbon nanotubes exceeds the above upper limit, the viscosity of the coating solution becomes too high, and the dispersibility of the carbon nanotubes may decrease due to reaggregation, which may make it difficult to form a uniform electrode layer. .

  When using a mixture of single-walled carbon nanotubes and multi-walled carbon nanotubes as the carbon nanotubes, (a) adding single-walled carbon nanotubes and multi-walled carbon nanotubes to separate dispersion media, and using a wet disperser After dispersing (or dissolving) in each dispersion medium, a single-walled carbon nanotube dispersion and a multi-walled carbon nanotube dispersion may be mixed to form an electrode layer forming coating solution. Alternatively, (b) a single-walled carbon nanotube and a multi-walled carbon nanotube may be simultaneously added to one dispersion medium, and dispersed (or dissolved) in the dispersion medium using a wet disperser to form an electrode layer forming coating solution. .

<Lamination process>
In the laminating step, the dielectric layer 3, the front side protective layer 8 and the back side protective layer 9 formed in the dielectric layer forming step are laminated in a predetermined order, and the electrode layer forming electrode prepared in the electrode layer forming coating liquid preparing step is laminated. The front side strip electrode layer 4 and the back side electrode layer 5 are formed by applying the coating liquid at a predetermined timing and drying it.

  Specifically, for example, the electrode layer forming coating solution is applied in a predetermined shape (stripe shape) to a predetermined position on the surface of the back side protective layer 9 formed in the dielectric layer forming step, and dried to form a stripe shape. A back-side electrode layer 5 composed of a plurality of back-side conductive portions arranged is formed. The stripe-shaped back side conductive portions are, for example, about 1 mm to 20 mm in width and about 50 mm to 500 mm in length, and are formed to be substantially parallel to each other with an interval of about 1 mm to 5 mm. At this time, if necessary, the electrode layer forming coating solution may be applied after masking a position where the back side conductive portion on the surface of the back side protective layer 9 is not formed. The drying conditions for the electrode layer forming coating solution are not particularly limited, and may be appropriately selected according to the type of the dispersion medium.

  Next, the dielectric layer 3 formed in the dielectric layer forming step is laminated on the back side protective layer 9 on which the back side electrode layer 5 is formed using a metal hand roller or the like, and the back side protective layer 9 and the dielectric layer 3 The dielectric layer 3 is laminated so that the back electrode layer 5 is sandwiched therebetween.

  Next, a plurality of front side conductive portions arranged in a stripe shape by applying and drying the electrode layer forming coating liquid in a predetermined shape (stripe shape) at a predetermined position on the front side surface of the dielectric layer 3 A front electrode layer 4 made of is formed. Here, as a method of forming the front electrode layer 4, a method similar to the method of forming the back electrode layer 5 can be employed.

  Finally, the front protective layer 8 formed in the dielectric layer forming step is laminated on the dielectric layer 3 on which the front electrode layer 4 is formed using a metal hand roller or the like, and the front protective layer 8 and the dielectric layer are laminated. The front side protective layer 8 is laminated so that the front side electrode layer 4 is sandwiched between the front side electrode layer 4 and the front side electrode layer 4.

  Through the above steps, the capacitive sensor sheet 2 having the configuration shown in FIGS. 1 and 2 can be manufactured. The manufacturing method of the sensor sheet 2 described here is a method in which the constituent members of the sensor sheet 2 shown in the schematic sectional view of FIG.

  In addition, in the manufacturing method of the sensor sheet mentioned above, before forming the front side electrode layer 4 or the back side electrode layer 5, in order to improve the adhesiveness of these with the front side protective layer 8 or the back side protective layer 9, The surface of the back side protective layer 9 may be pretreated. Similarly, before forming the front-side electrode layer 4 or the back-side electrode layer 5, a pretreatment may be performed on the front surface or the back surface of the dielectric layer 3 in order to improve the adhesion between them and the dielectric layer 3. However, when using a coating solution for forming an electrode layer containing carbon nanotubes as a conductive material, carbon nanotubes have extremely good adhesion to sheet-like materials such as dielectric layers. Sufficient adhesion can be secured without application. In addition, it is thought that the outstanding adhesiveness exhibited by containing a carbon nanotube is based on van der Waals force.

  Further, in the above method for producing a sensor sheet, when a dielectric layer or a protective layer is laminated, a primer solution may be applied in advance to the surface of the layer to be laminated. Examples of the primer solution include a toluene diluted solution of the raw material composition prepared in the dielectric layer forming step.

  The sensor sheet 2 can also be manufactured by, for example, the following method. After the dielectric layer and the protective layer are formed by the dielectric layer forming step, the front electrode layer 4 and the back electrode layer 5 are formed on both surfaces of the dielectric layer 3, respectively. And you may manufacture the sensor sheet 2 by laminating | stacking the front side protective layer 8 and the back side protective layer 9 in the further outer side which formed the front side electrode layer 4 and the back side electrode layer 5. FIG.

  Further, for example, after forming the dielectric layer and the protective layer by the dielectric layer forming step, after forming the front side electrode layer 4 on the surface of the front side protective layer 8 and forming the back side electrode layer 5 on the surface of the back side protective layer 9 The sensor sheet 2 may be manufactured by laminating the front side protective layer 8, the dielectric layer 3, and the back side protective layer 9 in a predetermined order. That is, the sensor sheet 2 may be manufactured by previously forming each electrode layer on either the dielectric layer in contact with the electrode layer or each protective layer, and then laminating the layers in a predetermined order.

  In addition, instead of the method of laminating the sheet-like material formed in advance as described above in a predetermined order, the raw material composition of the sheet-like material can be used for various purposes such as various coating apparatuses, bar coats, doctor blades, etc. The sensor sheet 2 may be manufactured by a method of sequentially stacking using a film forming apparatus or a film forming method.

〔advantage〕
The capacitance type sensor 1 and the method for measuring the amount of stretch deformation strain, the stretch deformation strain distribution or the surface pressure distribution include a selected one front-side conductive part to be detected and one when measuring the capacitance. When measuring the capacitance of the detection unit formed in the intersection region of the two back side conductive parts, all the front side conductive parts other than the selected one front side conductive part, and the selected one back side conductive part Since at least one of all the back side conductive parts other than is connected to the ground terminal 12, the capacitance due to the crosstalk is not added to the detection part to be detected, and the capacitance of the detection part is measured with high accuracy. can do. Since the capacitance type sensor 1 and the method for measuring the amount of stretch deformation strain, the stretch deformation strain distribution or the surface pressure distribution can measure the capacitance values of all the detection units with high accuracy, the stretch deformation strain The amount, stretch deformation strain distribution, surface pressure distribution and the like can be measured with high accuracy.

  In addition, since the capacitance type sensor 1 and the method of measuring the amount of expansion / contraction deformation strain, the expansion / contraction deformation strain or the surface pressure distribution can remove the capacitance due to crosstalk, the number of front side conductive portions or back side conductive portions can be reduced. Even if it is increased, the capacitance can be measured with high accuracy, and a large-size and high-accuracy capacitive sensor can be realized. In addition, since the capacitance can be measured with high accuracy even if the distance between the front conductive parts or the distance between the back conductive parts is reduced, the amount of stretch deformation strain distribution, stretch deformation strain distribution, and surface pressure distribution can be more precisely It is possible to realize a capacitive sensor that can measure the above.

  In addition, the capacitance type sensor 1 can measure the capacitance with high accuracy even when a load is applied to either the front side or the back side of the sensor sheet 2. Therefore, the capacitance type sensor 1 can use either the front surface or the back surface of the sensor sheet 2 as a utilization surface.

[Other Embodiments]
The present invention can be carried out in various modified and improved forms in addition to the above embodiment.

  That is, the number of arrangement of the front side conductive parts 01A to 16A and the back side conductive parts 01B to 16B in the above embodiment is set to 16, but the arrangement number is not particularly limited.

  In the above embodiment, the sensor sheet 2 includes the front side switching circuit 10 and the back side switching circuit 11 that switch the connection between the front side conductive part and the back side conductive part, and the measuring unit 6 and the ground terminal 12. 10 and the back side switching circuit 11 are not provided in the sensor sheet 2, but a circuit having a function of switching the connection between the front side conductive part and the back side conductive part and the measuring means 6 and the ground terminal 12 is provided separately from the sensor sheet 2. Also good. Moreover, in the said embodiment, although the sensor sheet 2 is provided with the front side wiring and the back side wiring in addition to the front side conductive part and the back side conductive part, if the front side conductive part and the back side conductive part can be connected to the measuring means 6, these wirings are Can be omitted.

  Further, as shown in FIG. 6, the measuring means 6 has a ground terminal whose potential is the ground level of the measuring means 6, and the control means selects one front conductive portion 04A and one selected back side. The conductive part 06B is connected to the measurement terminal of the measuring means 6 so that a constant voltage is applied, and the remaining front conductive parts 03A and 05A and / or the back conductive parts 05B and 07B are connected to the ground terminal of the measuring means 6 It is good also as composition to do. By connecting the conductive parts in this way, the potential of the front conductive parts 03A, 05A and / or the back conductive parts 05B, 07B that are not to be measured is made equal to the ground level of the measuring means 6, and the detection part C0406 to be measured. Since the addition of the capacitance due to the crosstalk to can be reduced, the measurement unit 6 can measure the capacitance of the detection unit C0406 with high accuracy. In addition, since the said effect is show | played if the electric potential of the electroconductive part which is not a measurement object becomes equal to the ground level of the measurement means 6, in the structure shown in FIG. 6, the measurement means 6 does not need to be earth | grounded.

  Moreover, although the said embodiment demonstrated the structure by which the front side protective layer 8 and the back side protective layer 9 were laminated | stacked on the surface side and back surface side of the dielectric layer 3, the structure by which the front side protective layer 8 and the back side protective layer 9 were abbreviate | omitted. It is good.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

<Production of dielectric layer>
100 parts by mass of hydrogenated hydroxyl-terminated liquid polyolefin polyol (Epoll from Idemitsu Kosan Co., Ltd.), 100 parts by mass of lubricating oil for high temperature (moresco high lube “LB-100” from MORESCO Co., Ltd.) mainly composed of alkyl-substituted diphenyl ether The mixture was weighed and stirred and mixed at 2000 rpm for 3 minutes using a rotation and revolution mixer (manufactured by Shinky Co., Ltd.). Next, 0.07 part by mass of a catalyst (Fomrez catalyst “UL-28” manufactured by Momentive) was added to the obtained mixture, and the mixture was stirred for 1.5 minutes with a rotation and revolution mixer. Thereafter, 11 parts by mass of isophorone diisocyanate (Desmodule I, Sumika Bayer Urethane Co., Ltd.) was added, stirred for 3 minutes with a rotating / revolving mixer, defoamed for 1.5 minutes, and then added to the film forming apparatus shown in FIG. While being injected and transported in a sandwich form with a protective film, it was cross-linked and cured under conditions of a furnace temperature of 110 ° C. and a furnace time of 30 minutes to obtain a roll-wound sheet with a predetermined thickness with a protective film. Thereafter, a crosslinking reaction was carried out in an oven adjusted to 80 ° C. for 12 hours to produce a dielectric layer having a layer thickness of 50 μm made of an elastomer composition containing an olefinic urethane rubber.

  The dielectric layer produced was measured for elongation at break (%), volume resistivity (Ωcm), and relative dielectric constant. As a result, the elongation at break (%) was 218% and the relative dielectric constant was 2.85. Here, the elongation at break was measured according to JIS-K6251. The relative dielectric constant was calculated from the electrode area and the thickness of the measurement sample by sandwiching a sheet-shaped measurement sample (dielectric layer) with an electrode having a diameter of 20 mm and measuring the capacitance with an LCR high tester.

<Production of electrode material>
(1) Single-walled carbon nanotube dispersion liquid As carbon nanotubes, super-growth CNT (hereinafter also referred to as “SGCNT”) (single-walled carbon nanotubes, average fiber diameter of about 3 nm, growth length of 500 μm to 700 μm, aspect ratio of about 100, 000, carbon purity 99.9%, provided by National Institute of Advanced Industrial Science and Technology (AIST), 50 mg is added to 24.95 g of methyl isobutyl ketone, and wet-dispersed using a jet mill (Nanojet Pal "JN10-SP003" from Joko Inc.) And 25 g of methyl isobutyl ketone was further added to obtain a single-walled carbon nanotube dispersion liquid having a concentration of 0.1% by mass. The growth length of the carbon nanotube refers to the height of the forest grown on the growth substrate when producing the carbon nanotube, and substantially corresponds to the average fiber length of the carbon nanotube.

(2) Multi-walled carbon nanotube dispersion As a multi-walled carbon nanotube, 50 mg of “NC7000” (average fiber diameter 9.5 nm, average fiber length 1.5 μm, aspect ratio 158, carbon purity 90%) manufactured by Nanosil Co., Ltd. Add to 95 g, apply wet dispersion using jet mill (Nanojet Pal "JN10-SP003" from Joko, Inc.), add 25 g of methyl isobutyl ketone, and disperse multi-walled carbon nanotubes with a concentration of 0.1% by mass A liquid was obtained.

(3) Carbon nanotube mixed dispersion The above-mentioned single-walled carbon nanotube dispersion and the above-mentioned multi-walled carbon nanotube dispersion are mixed at 30:70 (mass ratio), and a carbon nanotube coating comprising a mixture of single-walled carbon nanotubes and multi-walled carbon nanotubes is applied. A liquid (coating liquid for forming an electrode layer) was obtained.

<Preparation of protective layer>
A protective layer having a layer thickness of 50 μm made of an elastomer composition containing an olefinic urethane rubber was produced using the same method as that for producing the dielectric layer described above.

<Preparation of primer solution>
A 0.1 wt% toluene solution prepared by dissolving a composition having the same composition as the raw material composition for the dielectric layer in toluene was prepared as a primer solution.

<Production of sensor sheet>
The electrode layer-forming coating solution obtained above was applied in a stripe shape with an air brush on the back side of the dielectric layer produced above and dried. The belt-like back side conductive portion was formed with 8 pieces having an average thickness of about 1 μm, a width of 10 mm, and a length of 137 mm at intervals of 5 mm. Next, 8 g of the primer solution was applied with an air brush from the back side electrode layer on the back side of the dielectric layer, and dried at 100 ° C. for 30 minutes. Thereafter, the primer solution was applied to the back surface of the dielectric layer, the protective layer was laminated using a metal hand roller, and the back side protective layer was laminated so that the back side electrode layer was sandwiched between the dielectric layer. Next, the electrode layer forming coating solution was applied to the surface side of the dielectric layer in a stripe shape so as to be orthogonal to the back side conductive portion, and the front electrode layer was formed in the same manner. After forming the front electrode layer on the surface of the dielectric layer, 8 g of a primer solution was applied with an air brush and dried at 100 ° C. for 30 minutes. Furthermore, after applying this primer solution, the front side protective layer was laminated in the same manner.

  Subsequently, both ends of each strip-shaped conductive portion were reinforced with a 0.1 mm thick copper foil, and lead wires of external wiring were screwed and connected. This sensor sheet had a capacitance of 50 pF in one detection portion (each portion distributed in a matrix in which the front-side conductive portion and the back-side conductive portion intersect in plan view).

<Configuration of capacitance sensor for evaluation>
The schematic diagram of the wiring of the capacitive sensor used for the evaluation is as shown in FIGS. However, in FIG. 3 and FIG. 4, only three front side conductive parts and back side conductive parts are shown for easy understanding of the connection configuration. Actually, there are eight front-side conductive portions and eight back-side conductive portions, and some of the front-side conductive portions and the back-side conductive portions are not shown in FIGS.

  An LCR meter (LCR Hitester “3522-50” manufactured by Hioki Electric Co., Ltd.) was used as the measuring means 6 for measuring the capacitance. A 4-terminal probe of model number 9140 was used as the measurement probe. A lead wire was connected to a connection portion provided at each end of the front-side conductive portion and the back-side conductive portion of the produced sensor sheet, and connected to an evaluation terminal block to which an LCR meter was connected. Two DIP switches for each conductive part are provided on the terminal block for evaluation. For each conductive part, connection to the measurement terminal of the LCR meter is turned on / off, and a ground provided separately from the LCR meter. The connection to the terminal can be switched on / off.

[Example 1]
The LCR meter is set to an output voltage of 1 V, a measurement time of SLOW (88 ms), an average count of 8 times, a frequency of 5 kHz, and all formed in a region where the front side conductive part and the back side conductive part intersect in plan view. The respective electrostatic capacities of the detection parts (64 locations) were measured. As shown in FIG. 3, when the LCR meter measures the capacitance of one detection unit (detection unit C0406), one front side conductive unit (front side conductive unit 04A) and one back side corresponding to the detection unit Switch the DIP switch so that the conductive part (back side conductive part 06B) is connected to the measurement terminal of the LCR meter, and all other front side conductive parts and back side conductive parts are connected to the ground terminal. The capacity was measured. For all the detection units, the capacitance was measured while switching the DIP switch so that the front side conductive unit and the back side conductive unit were connected in the same manner.

[Example 2]
The LCR meter is set to an output voltage of 1 V, a measurement time of SLOW (88 ms), an average count of 8 times, a frequency of 5 kHz, and all formed in a region where the front side conductive part and the back side conductive part intersect in plan view. The respective electrostatic capacities of the detection parts (64 locations) were measured. As shown in FIG. 4, when the LCR meter measures the capacitance of one detection unit (detection unit C0406), the back side conductive unit (back side conductive unit 06B) corresponding to the detection unit is connected to the measurement terminal of the LCR meter. All other back side conductive parts are connected to the ground terminal, and one front side conductive part (front side conductive part 04A) corresponding to the detection part is connected to the other measurement terminal of the LCR meter, All the front side conductive parts other than were opened without being connected to the ground terminal, and the capacitance of the detection part to be detected was measured. For all the detection units, the capacitance was measured while switching the DIP switch so that the front side strip electrode layer and the back side strip electrode layer were connected in the same manner.

[Comparative Example 1]
Similar to Example 1, the output voltage of the LCR meter is 1 V, the measurement time is SLOW (88 ms), the average number of times is 8 times, the frequency is 5 kHz, and the front side conductive part and the back side conductive part intersect in plan view The respective electrostatic capacitances were measured for all the detection portions (64 locations) formed in the above. In FIG. 7, the schematic diagram of the wiring of the capacitive sensor in the comparative example 1 is shown. As shown in FIG. 7, when the LCR meter measures the capacitance of one detection unit (detection unit C0406), one front side conductive unit (front side conductive unit 04A) corresponding to the detection unit and one back side Connect the conductive part (back side conductive part 06B) to the measurement terminal of the LCR meter, switch the DIP switch to open all other front side conductive parts and back side conductive parts, and measure the capacitance of the detection part did. That is, all the front side conductive parts and back side conductive parts other than the front side conductive part and the back side conductive part to be measured were opened without being connected to the ground terminal, and the capacitance of the detection part to be measured was measured. For all the detection units, the capacitance was measured while switching the DIP switch so that the front side conductive unit and the back side conductive unit were connected in the same manner.

<Evaluation>
Using the measurement methods shown in Example 1, Example 2, and Comparative Example 1, the following evaluation was performed.

[Capacitance measurement]
For the capacitive sensors of Examples 1, 2 and Comparative Example 1 using the flat sensor sheet produced as described above, the capacitance of the electrostatic capacity sensor is set to 5 kHz without changing the sensor sheet and the measurement frequency of the LCR meter is 5 kHz. Measurements were made. The measurement results of the respective capacitances in Example 1, Example 2 and Comparative Example 1 are shown in FIG. 8 (a), FIG. 8 (b) and FIG. 8 (c).

  8A, FIG. 8B, and FIG. 8C, X indicates the position in plan view of the front conductive portion connected to the output terminal X of the LCR meter of FIG. 3, FIG. 4 and FIG. 8A, FIG. 8B, and FIG. 8C, Y indicates the position in plan view of the back side conductive portion connected to the output terminal Y of the LCR meter. That is, the intersections of X and Y in FIGS. 8A and 8B indicate the positions of the detection units formed in a matrix in plan view. And the electrostatic capacitance in each detection part is shown in the Z-axis direction perpendicular to the XY plane. That is, in FIG. 8A, FIG. 8B, and FIG. 8C, the capacitance distribution on the sensor sheet is shown in 3D display.

  As shown in FIG. 8C, in the case of Comparative Example 1, a capacitance of about 221 pF, which is larger than 50 pF, which is the theoretical value calculated by the above formula (1), is measured in all the detection units. ing. This is because the capacitance due to crosstalk was added and measured. On the other hand, in the case of Example 2, as shown in FIG. 8B, a capacitance of 55 pF, which is slightly higher than the theoretical value, was measured in all the detection units. As a result, the crosstalk capacitance can be largely eliminated by connecting the back side conductive portion other than during measurement to the ground without connecting the front side conductive portion other than during measurement to the ground, and the capacitance is generally accurate. It was confirmed that can be measured. In the case of Example 1, as shown in FIG. 8A, a capacitance of about 50 pF close to the theoretical value was measured in all the detection units. Thus, it was confirmed that the crosstalk capacitance can be almost completely removed by connecting the conductive portion other than that being measured to the ground, and the accurate capacitance can be measured.

[Measurement of change in capacitance with measurement frequency]
Next, the measurement frequency of the LCR meter was changed, and the capacitance of the detection unit was measured using the capacitance type sensors of Example 1, Example 2, and Comparative Example 1. FIG. 9A, FIG. 9B, and FIG. 9C show the relationship between the measurement frequency and capacitance in Example 1, Example 2, and Comparative Example 1, respectively.

  9 (a), 9 (b) and 9 (c), the horizontal axis indicates the measurement frequency of the LCR meter, and the vertical axis indicates FIGS. 8 (a), 8 (b) and 8 (c). ) Indicates the capacitance of the detection unit at the position of the coordinates (X8, Y8). The measurement frequency of the LCR meter was changed stepwise from 100 Hz to 100 kHz, and the capacitances of the detectors measured in Example 1, Example 2 and Comparative Example 1 using the respective measurement frequencies were respectively shown in FIG. Plotted in a), FIG. 9 (b) and FIG. 9 (c).

  As shown in FIGS. 9A and 9B, in the case of Example 1 and Example 2, the change in the measured capacitance due to the change in the measurement frequency is small, and the measurement frequency close to the theoretical value. It can be seen that the capacitance can be measured with high accuracy. As shown in FIG. 9 (c), in the case of Comparative Example 1, the measurement frequency increases and the measured capacitance decreases, but the added capacitance due to crosstalk is large and the measurement frequency is large. It can be seen that a capacitance larger than the theoretical value is still measured.

[Measurement of capacitance using deformed sensor sheet]
In contrast to the capacitive sensors of Examples 1, 2 and Comparative Example 1 using the flat sensor sheet produced as described above, a part of the sensor sheet is deformed so that the measurement frequency of the LCR meter is 5 kHz. The capacity was measured. Specifically, of the flat sensor sheet, the portion corresponding to the position of the coordinates (X3, Y3) and the position of the coordinates (X6, Y7) in FIG. Using a rounded product, the sensor sheet was sunk so that the distance between the top portion that was deformed and protruded and the flat portion that was not deformed was 12.7 mm. The photograph which image | photographed this deformed sensor sheet from the upper part and the side is shown to Fig.10 (a) and FIG.10 (b). Moreover, the measurement result of each electrostatic capacitance in Example 1, Example 2, and the comparative example 1 is shown to Fig.11 (a), FIG.11 (b), and FIG.11 (c). Further, each capacitance change ΔC is shown in FIGS. 12 (a), 12 (b), and 12 (c).

  11 (a), 11 (b) and 11 (c) show the above modified sensor sheet on the same graph as FIG. 8 (a), FIG. 8 (b) and FIG. 8 (c). The electrostatic capacitance in each detection part measured using was shown.

  In FIG. 11C, it is difficult to confirm an increase in capacitance due to deformation of the sensor sheet, whereas in FIG. 11A and FIG. 11B, increase in capacitance due to deformation of the sensor sheet is clearly shown. It can be seen that it can now be confirmed. This is because, in the case of Comparative Example 1, the capacitance in the undeformed state has increased to 221 pF due to the addition of the capacitance due to crosstalk. Even if a value of about 12 pF) is added, since the ratio to the capacitance in the undeformed state is small, it is difficult to confirm an increase in the capacitance as shown in FIG. From this result, it was confirmed that the sensitivity was improved by using the capacitance type sensors of Example 1 and Example 2.

  FIG. 12 is a graph similar to FIG. 8, in the Z-axis direction perpendicular to the XY plane, the increase in capacitance ΔC (measured with the deformed sensor sheet) measured with the deformed sensor sheet for each detection unit. The value obtained by subtracting the capacitance measured with a flat sensor sheet not deformed from the capacitance) is shown. That is, in FIG. 12A, FIG. 12B, and FIG. 12C, the distribution of the capacitance change on the sensor sheet is shown in 3D display.

  In FIG. 12B, it can be seen that there is a undulation of the capacitance change amount ΔC other than the deformed portion of the sensor sheet. On the other hand, in FIG. 12A and FIG. 12B, it can be seen that there is no undulation other than the deformed portion of the sensor sheet. Thus, it was confirmed that the accuracy was improved by using the capacitance type sensors of Example 1 and Example 2.

  From FIG. 12, it can be seen that the capacitance change ΔC is larger in the case of the comparative example 1 than in the cases of the first and second embodiments. The reason why the capacitance change amount ΔC is large in the comparative example 1 is that the original capacitance calculated from the above formula (1) does not increase when the detection unit at the undeformed position is increased, but the deformation of the sensor sheet This is because the measured capacitance increases as the crosstalk capacitance added to the capacitance increases, and as a result, the capacitance change amount ΔC increases. For example, regarding the detection unit C0307 that has not been deformed, along with the deformation of the coordinates (X3, Y3) and the coordinates (X6, Y7), the detection unit C0303, the detection unit C0607, and the neighboring detection units It is considered that the capacitance increases, and the increase in capacitance affects the detection unit C0307 due to crosstalk, and the capacitance of the detection unit C0307 also increases.

  Furthermore, the capacitance added by crosstalk will be described in detail based on the above-described measurement result of capacitance.

  A case where the capacitance of the detection unit C0307 is measured in a state where the sensor sheet is not deformed will be described. When a measurement signal for measuring the capacitance is input from the front side conductive portion 03A, the measurement signal passes through the detection portion C0307, passes through the back side conductive portion 07B, and is connected to the measurement means 6, thereby detecting the detection portion. Although the capacitance of C0307 can be measured, there are other routes through which this measurement signal can pass. In one of the routes, for example, a measurement signal is input from the front-side conductive unit 03A, passes through the detection unit C301, passes through the back-side conductive unit 01B, passes through the detection unit C0101, passes through the front-side conductive unit 01A, and passes through the detection unit C0107. There is a route connected to the measuring means 6 through the back side conductive portion 07B. In this case, in addition to the original capacitance of 50 pF of the detection unit C0307, a combined capacitance (here, about 3.37 pF) in which the detection units C0301, C0101, and C0107 are connected in series is added.

  Similarly, the combined capacitance (3.37 pF) obtained by connecting the detection units C0303, C0103, and C0107 in series is added to the original capacitance 50 pF of the detection unit C0307. Similarly, a combined capacitance (3.37 pF) in which the detection units C0303, C0603, and C0607 are connected in series is also added. In this way, in the concept of passing through three detection units other than the detection unit C0307 being measured in series, there are 49 passage routes, and 165 pF (3.37 pF × 49) is the original electrostatic capacitance of the detection unit C0307. The capacitance is added to 50 pF and measured as 215 pF. The result of actually producing and measuring the sensor sheet was 221 pF in terms of the average value of 64 detection portions.

  Moreover, although the said sensor sheet was made into 8x8 front side conductive parts and back side conductive parts, in the sensor sheet produced on the same conditions as the above sensor sheet as 5x5 front side conductive parts and back side conductive parts The capacitances of the routes other than the measurement route are 5.6 pF × 16, and the crosstalk capacitance of 90 pF is added to the original capacitance of 50 pF to 140 pF. The result of actual fabrication and measurement was 139 pF.

  From this, the larger the number of stripe-shaped conductive portions, the larger the proportion of electrostatic capacitance added by crosstalk, so when manufacturing a large sensor sheet with more conductive portions, the present invention. It can be said that the effect of is remarkable.

  In the case of Comparative Example 1, as shown in FIG. 12C, the detection unit at the position where the deformation is applied and the detection unit (coordinates (X3, Y3) and coordinates (X6) sharing the front-side conductive unit and the back-side conductive unit). , Y7), which are on the same X and Y lines), these detectors have a large increase in capacitance ΔC compared to the other parts despite the undeformed state. You can see that

  This is considered due to the following reasons. Similarly to the above, a case where the capacitance of the detection unit C0307 is measured will be described. In the detection part sharing the front side conductive part or the back side conductive part with the detection parts C0303 and C0607 in the deformed position, the ratio of the route passing through the deformed position detecting parts C0303 and C0607 in the 49 routes is increased. It is considered that the amount of addition of the crosstalk capacitance is larger than that of the detection units C0303 and C0607 at the deformed position and the other detection units that do not share the front conductive part or the back conductive part. In other words, among the 49 passage routes that have the influence of crosstalk when measuring the capacitance of the detection unit C0307, the detection units C0303 and C0607 in which the capacitance increases due to deformation of the sensor sheet and the surroundings In the route passing through the detection unit, the combined capacitance due to the series connection of the detection units in the route is increased from 3.37 pF in a state where the sensor sheet is not deformed.

  In the detection unit C0307 at the position where deformation is not applied, there are seven routes passing through the detection unit C0303 at the deformation position, and similarly there are seven routes passing through the detection unit C0607 at the deformation position, for a total of 14 routes. . Among them, one route passes through both the detection unit C0307 and the detection unit C0607. Since there are many routes that pass through the detection unit at the deformed position among all 49 routes, the detection unit C0307 has a larger capacitance due to crosstalk than the other detection units.

  Similarly, in the detection unit C0306 at the position where deformation is not applied, there are seven routes passing through the detection unit C0303 at the deformation position, and one route passing through the detection unit C0607 at the deformation position, for a total of eight routes. It is. Similarly, in the detection unit C0206 at a position where deformation is not applied, there are one route that passes through the detection unit C0303 that is subjected to deformation, and one route that passes through the detection unit C0607 that is also subjected to deformation. In this case, the addition of capacitance due to crosstalk is small.

  The detection unit C0307 is a conductive unit in which the corresponding front-side conductive unit 03A and back-side conductive unit 07B are shared with the detection units C0303 and C0607 both in the deformation region. The detection unit C0306 is a conductive unit that is shared with the detection unit C0303 in which only the front-side conductive unit 03A among the corresponding front-side conductive unit 03A and back-side conductive unit 06B is in the deformation region. The detection unit C0206 is a conductive unit that is not shared with the detection unit in the deformation region in any of the corresponding front-side conductive unit 02A and back-side conductive unit 06B. Therefore, as described above, the addition of the crosstalk capacity due to the deformation of the sensor sheet is the largest in the detection unit C0307, and decreases in the order of the detection unit C0306 and the detection unit C0206.

  The capacitance type sensor of the present invention and the method for measuring the amount of stretching deformation strain, stretching strain distribution or surface pressure distribution can remove the crosstalk capacitance and measure the capacitance with high accuracy. Distribution, stretch deformation amount, stretch deformation strain distribution, etc. can be measured with high accuracy. The capacitive sensor of the present invention can be used as, for example, a sensor for tracing the shape of a flexible object, a sensor for measuring the movement of a measurement object such as a person, and the like. More specifically, for example, deformation of the shoe sole inner by the sole, deformation of the seat cushion by the buttocks can be measured. Moreover, the capacitive sensor of the present invention can be used as an input interface for a touch panel, for example. The capacitance type sensor of the present invention can also be used for measurement at a light shielding portion that cannot be measured by an optical motion capture which is an existing sensor.

DESCRIPTION OF SYMBOLS 1 Capacitance type sensor 2 Sensor sheet 3 Dielectric layer 4 Front side electrode layer 5 Back side electrode layer 6 Measuring means 7 Control means 8 Front side protective layer 9 Back side protective layer 10 Front side switching circuit 11 Back side switching circuit 12 GND terminal 01A1-16A1 Front side connection Part 01A-16A Front side conductive part 01a-16a Front side wiring 01B1-16B1 Back side connection part 01B-16B Back side conductive part 01b-16b Back side wiring C0101-C1616 Detection part 03A2-05A2, 05B2-07B2, 03A3-05A3 Switch 13, 13 ' Roll 14 Raw material composition 15 Heating device 16 Dielectric layer 17 Protective film

Claims (8)

A dielectric layer comprising an elastomer composition;
A front-side electrode layer comprising a plurality of front-side conductive portions stacked on the surface side of the dielectric layer and arranged in a stripe shape;
A back-side electrode layer comprising a plurality of back-side conductive portions stacked on the back side of the dielectric layer and arranged in a stripe shape so as to be substantially orthogonal to the plurality of front-side conductive portions in plan view;
A capacitance-type sensor comprising a measuring unit that measures the capacitance of a detection unit formed in each crossing region of the plurality of front-side conductive units and the plurality of back-side conductive units in plan view,
Each of the conductive parts includes a carbon nanotube,
The selected one front-side conductive part and the selected one back-side conductive part are connected to the measuring means so that a constant voltage is applied, and the remaining front-side conductive part and / or the remaining back-side conductive part is connected. A capacitive sensor comprising a control means for grounding the capacitor.   The capacitive sensor according to claim 1, wherein an average fiber diameter of the carbon nanotube is 0.5 nm or more and 30 nm or less.   3. The capacitive sensor according to claim 1, wherein each of the conductive parts includes 30 mass% or more of carbon nanotubes having an average fiber length of 100 μm or more and 700 μm or less with respect to the total solid component.   4. The capacitive sensor according to claim 1, wherein an average thickness of the front-side conductive portion and the back-side conductive portion is 0.1 μm or more and 10 μm or less. 5.   The capacitive sensor according to any one of claims 1 to 4, wherein the elastomer composition includes urethane rubber as a main component.   The capacitive sensor according to any one of claims 1 to 5, wherein an extension ratio of the dielectric layer in one axial direction is 30% or more.   The capacitive sensor according to any one of claims 1 to 6, wherein an amount of expansion / contraction deformation strain, an expansion / contraction deformation strain distribution, or a surface pressure distribution is measured based on a measurement result of the measurement unit. A dielectric layer made of an elastomer composition, a front electrode layer made up of a plurality of front side conductive parts arranged in a striped manner on the surface side of the dielectric layer, and laminated on the back side of the dielectric layer, in plan view And a plurality of backside conductive layers arranged in stripes so as to be substantially orthogonal to the plurality of frontside conductive portions, and the plurality of frontside conductive portions and the plurality of backside conductive portions in plan view And a method of measuring the amount of stretch deformation strain, stretch deformation strain distribution or surface pressure distribution using a sensor sheet in which a detection unit is formed in each intersection region,
Each of the conductive parts includes a carbon nanotube,
One selected front side conductive part and one selected back side conductive part are connected to the measuring means so that a constant voltage is applied, and the remaining front side conductive part and / or the remaining back side conductive part is connected Having a step of measuring the electrostatic capacitance of the detection part of the intersection region by ground connection,
A method for measuring a stretching deformation strain distribution, a stretching deformation strain distribution or a surface pressure distribution, wherein the detection unit is sequentially switched for all combinations of front conductive portions and back conductive portions, and the measurement step is repeated.