JP2012159463A - Pressure-sensitive sensor body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive sensor body capable of stably obtaining a pressure-sensitive characteristic by reducing a stress received from a pressure that is repeatedly applied to a pressure-sensitive conducting member and, even when receiving the applied pressure multidirectionally or locally, suppressing attributable dispersion in a contact area.SOLUTION: The pressure-sensitive sensor body includes at least: an electrode substrate provided with at least a pair of electrodes on the substrate; the pressure-sensitive conducting member of which electric resistance value is changed by a change in the contact area with the electrode substrate when receiving the pressure; an insulation coating member covering at least a pressure application surface of the pressure-sensitive conducting member; and a wiring part conducting with the electrodes respectively. The insulation coating member includes at least an adhesive layer and a flexible film that has Young's modulus of not less than 1.7 GPa and not more than 6.5 GPa and has a thickness of not less than 10 μm and not more than 100 μm. The adhesive layer is stuck to the electrode substrate, so that the pressure-sensitive conducting member is fixed onto the electrode substrate.

Description

  The present invention relates to a pressure-sensitive sensor body using a pressure-sensitive conductive member that exhibits a high electrical resistance value in a non-pressurized state and decreases in electrical resistance value according to compressive deformation accompanying an increase in pressure and exhibits conductivity.

  Conventionally, a method using piezoelectric ceramics such as lead zirconate titanate or a method using a strain gauge has been used as means for measuring the magnitude and distribution of pressure acting on a member. However, since the method using piezoelectric ceramics generally uses a material with high rigidity, the degree of freedom of the shape of the pressure sensor is limited, and the method using a strain gauge is also similar to the shape of the pressure sensor. There is a problem that the degree of freedom of design is low.

  In response to these problems, a polymer material such as rubber, elastomer, or resin material is used as a base material, and a conductive member in which conductive particles are dispersed in the base material is used. It is known that a pressure sensor can be obtained.

  The pressure-sensitive characteristics due to the conductive member are roughly classified into the following two types. One of them shows a high electrical resistance value when no pressure is applied, but due to compressive deformation accompanying an increase in pressure, the interparticle distance between conductive particles in the substrate is narrowed, and a conductive path is formed by the conductive particles. This is a resistance value change type in which the electrical resistance value is reduced by being applied. In addition, since this resistance value change is greatly influenced by the dispersion state of the conductive particles in the base material, the reproducibility of the electrical resistance value change due to repeated compression deformation is a problem. In particular, during repeated pressing, the conductive member undergoes permanent deformation due to fatigue, and the conductive particles remain in contact with each other, making it difficult to detect pressure.

  The other type is a type in which a conductive coating film is formed using the conductive member, and the conductive coating films, or the conductive coating film and, for example, a comb-shaped electrode are arranged to face each other. In the case of this type of pressure-sensitive sensor body, as the pressure increases, the contact area between the conductive coating films or the contact area between the conductive coating film and the comb electrode changes, thereby changing the conduction state. Therefore, it is possible to detect a change in pressure as a change in electrical resistance value, which can be said to be a contact area change type.

  Such a pressure-sensitive sensor body is composed of at least a conductive member for obtaining pressure sensitivity and an electrode substrate serving as an output path for the change in resistance value. Furthermore, the pressure-sensitive conductive member and the electrode substrate are fixed or the pressure-sensitive conductive member is pressed against the electrode substrate so that stable pressure-sensitive performance can be maintained during use.

  For example, a pressure-sensitive sensor characterized in that a short side of a strip-shaped pressure-sensitive conductive rubber is bonded and fixed to an electrode substrate, and at least a part of the long side is not bonded and fixed, and a flexible protective film thereon Has been proposed (Patent Document 1). Further, a pressure sensor has been proposed in which a strip of pressure-sensitive conductive rubber is disposed between a pair of electrodes provided on a flexible electrode substrate at an interval and fixed with an adhesive tape ( Patent Document 2). Further, in the pressure-sensitive conductive sensor in which the pressure-sensitive conductive elastic body is provided on the comb-like electrode, the pressure-sensitive conductive elastic body is covered with a thin skin (film or the like) with pressure. A piezoelectric sensor has been proposed (Patent Document 3).

JP 2005-351653 A JP-A-4-38432 JP 2001-195945 A

  The pressure-sensitive sensor body of Patent Document 1 obtains a stable pressure-sensitive characteristic without shifting the relative positional relationship by providing an adhesive layer between the pressure-sensitive conductive rubber and the electrode substrate and fixing them. Can do. However, the presence of the adhesive layer not only fixes the pressure-sensitive conductive rubber and the electrode substrate, but also affects the pressure-sensitive characteristics as a spacer. Therefore, the thickness accuracy of the adhesive layer causes variations in the pressure-sensitive characteristics. It may become. This effect is particularly noticeable when applied to the above-described contact area change type pressure-sensitive sensor body, and the pressure-sensitive conductive member that can be used must be restricted. In addition, since the protective film is provided in a relaxed manner, for example, when pressure is repeatedly applied to the sensor surface locally or when pressure is applied from multiple directions, the film material is stretched and the dimensions change. As a result, wrinkles are generated or biased, and pressure is not accurately transmitted to the pressure-sensitive conductive member, and the function as a pressure-sensitive sensor may be impaired.

  Since the polyethylene pressure-sensitive adhesive tape used in the pressure-sensitive sensor body of Patent Document 2 has low rigidity, there are concerns about problems due to deformation and deterioration of the tape material due to repeated use.

  In the pressure-sensitive sensor body of Patent Document 3, a pressure-sensitive conductive elastic body is provided on a comb-shaped electrode, and the pressure-sensitive conductive elastic body is covered with a thin skin so that pressure is constantly applied to the pressure-sensitive conductive elastic body. When the pressure sensor body is released after pressure is applied by the pusher, the shape recovery property of the thin skin itself acts in addition to the shape recovery property of the pressure-sensitive conductive elastic body. It is assumed that the variation in pressure-sensitive characteristics when the pressure is increased or decreased is reduced. However, when a pressure is constantly applied to the pressure-sensitive conductive elastic body, the electric resistance value is lowered by itself, so that even if pressure is applied from that state, the variation range of the electric resistance value becomes small. That is, since the sensitivity as a pressure-sensitive sensor and the pressure range that can be sensed are narrowed, there is a concern that the range that can be used as a sensor is greatly impaired and the application is limited.

  Based on the above, in order to solve the above problems, the present inventors provide an insulating layer having appropriate rigidity and thickness on the pressure application surface in a contact area change type pressure-sensitive conductive member. It was found that durability and pressure-sensitive stability can be obtained. The object of the present invention is to reduce the stress that the pressure-sensitive conductive member of the contact area change type receives from the repeatedly applied pressure, and even if the applied pressure is received in multiple directions or locally, the contact area variation caused by this An object of the present invention is to provide a pressure-sensitive sensor body capable of stably obtaining pressure-sensitive characteristics by suppressing the above.

  The present invention provides an electrode substrate having at least a pair of electrodes on the substrate, a pressure-sensitive conductive member whose electrical resistance value changes due to a change in contact area between the electrode substrate and the pressure substrate when subjected to pressure, and at least the pressure-sensitive member In a pressure-sensitive sensor body having at least an insulating covering member that covers a pressure application surface of a conductive member and a wiring portion that is electrically connected to each of the electrodes, the insulating covering member includes an adhesive layer, a Young At least 1.7 GPa or less and a flexible film having a thickness of 10 μm or more and 100 μm or less, and the pressure-sensitive conductive member is bonded to the electrode substrate by attaching the pressure-sensitive adhesive layer to the electrode substrate. It is a pressure sensitive sensor body characterized by being fixed on top.

  The pressure-sensitive sensor body of the present invention reduces the stress that the pressure-sensitive conductive member of the contact area change type receives from the repeatedly applied pressure, and the contact caused by this even when the applied pressure is received in multiple directions or locally. Variation in area can be suppressed, and stable pressure-sensitive characteristics can be obtained.

It is a figure which shows one Embodiment of the pressure-sensitive sensor body which concerns on this invention. It is the perspective view which looked at the pressure-sensitive sensor body shown in FIG. 1 from the A direction. It is a figure which shows other embodiment of the pressure-sensitive sensor body which concerns on this invention. It is the perspective view which looked at the pressure-sensitive sensor body shown in FIG. 3 from the A direction. It is a schematic diagram of the comb-like electrode in an Example. It is a figure which shows the measuring method of the electrical resistance value change of the pressure-sensitive sensor body by a load. It is a figure which shows the load location to the pressure-sensitive sensor body in an Example. It is a figure which shows the relationship between the load in the pressure-sensitive sensor body of Example 1, and an electrical resistance value. It is a figure which shows the relationship between the load in the pressure-sensitive sensor body of Example 2, and an electrical resistance value. It is a figure which shows the relationship between the load in the pressure-sensitive sensor body of the comparative example 1, and an electrical resistance value. It is a figure which shows the relationship between the load in a pressure-sensitive sensor body of the comparative example 2, and an electrical resistance value.

  The present invention provides an electrode substrate having at least a pair of electrodes on the substrate, a pressure-sensitive conductive member whose electrical resistance value changes due to a change in contact area between the electrode substrate and the pressure substrate when subjected to pressure, and at least the pressure-sensitive member In a pressure-sensitive sensor body having at least an insulating covering member that covers a pressure application surface of a conductive member and a wiring portion that is electrically connected to each of the electrodes, the insulating covering member includes an adhesive layer, a Young At least 1.7 GPa or less and a flexible film having a thickness of 10 μm or more and 100 μm or less, and the pressure-sensitive conductive member is bonded to the electrode substrate by attaching the pressure-sensitive adhesive layer to the electrode substrate. It is a pressure sensitive sensor body characterized by being fixed on top.

<Insulating coating member>
The pressure-sensitive sensor body according to the present invention has an insulating covering member that covers at least the pressure application surface of the pressure-sensitive conductive member. The first purpose of providing the insulating covering member is to suppress and stabilize the variation in pressure-sensitive characteristics due to various pressure forms. When pressure is applied to the pressure-sensitive sensor body from the outside, the pressure is transmitted to the pressure-sensitive conductive member through the flexible film. When using a pressure-sensitive conductive member of a contact area change type, in order to obtain a stable pressure-sensitive characteristic, the pressure-sensitive conductive member and the electrode substrate when the pressure-sensitive conductive member receives a certain pressure are used. It is important to keep the contact state constant. By transmitting the pressure together with the insulating covering member having a certain rigidity as in the present invention, even if the form of various pressures, that is, the shape of the pusher and the angle of the applied pressure changes depending on the application, the pressure sensitive Since a stable contact area can be ensured by dispersing pressure over the entire surface of the conductive member, stable pressure-sensitive characteristics that are not affected by the form of pressure can be obtained.

  The second purpose of providing the insulating covering member is to protect the pressure-sensitive conductive member. When the pressure-sensitive sensor body is downsized or softened, a pressure-sensitive conductive member in which a conductive material is mixed with rubber or elastomer is often selected. The insulating covering member prevents deformation and deterioration of these materials due to repeated pressure, stress concentration, and the like.

[Flexible film]
The insulating covering member has at least a pressure-sensitive adhesive layer and a flexible film having a Young's modulus of 1.7 GPa to 6.5 GPa and a thickness of 10 μm to 100 μm. The effect of the present invention can be more preferably obtained when the Young's modulus is 3.0 GPa or more and 4.0 GPa or less. When the Young's modulus is less than 1.7 GPa, when pressure is applied, the pressure dispersion to the entire pressure-sensitive conductive member becomes insufficient, resulting in variations in pressure-sensitive characteristics, and the durability against protection also decreases. On the other hand, when the Young's modulus exceeds 6.5 GPa, due to its rigidity, the bent shape at the time of pasting cannot be maintained, and it tries to return to the original substantially flat plate shape. Therefore, there exists a possibility that an insulating coating member may peel from an electrode substrate at the time of use. Or even if it does not peel, the force works so as to always press the pressure-sensitive conductive member against the electrode substrate surface, so that the contact area at no load increases, and the electric resistance value indicating the sensitivity of the pressure-sensitive sensor body The range of change is greatly impaired.

  The thickness of the flexible film is 10 μm or more and 100 μm or less. The effect of the present invention can be more preferably obtained when the thickness is 25 μm or more and 75 μm or less. If it is less than 10 μm, even if the Young's modulus is in the above range, the effect of uniformly transmitting the applied pressure to the entire pressure-sensitive conductive member and the protective effect are insufficient. Moreover, when exceeding 100 micrometers, it tries to return to the original substantially flat form, without maintaining the bent shape at the time of sticking by the thickness. Therefore, there exists a possibility that an insulating coating member may peel from an electrode substrate at the time of use. Or even if it does not peel, the force works so as to always press the pressure-sensitive conductive member against the electrode substrate surface, so that the contact area at no load increases, and the electric resistance value indicating the sensitivity of the pressure-sensitive sensor body The range of change is greatly impaired.

  The material of the flexible film is not particularly limited as long as it is insulative and satisfies the above Young's modulus and thickness. For example, biaxially stretched nylon film, polyimide film, polyethylene terephthalate film, polysulfene sulfide film , Selected from polystyrene film and the like.

(Adhesive layer)
The insulating covering member has at least an adhesive layer and a flexible film. The pressure-sensitive adhesive layer is provided on at least one surface of the flexible film, for example. Since the insulating covering member has the pressure-sensitive adhesive layer, in addition to the above-described effects, the insulating covering member also functions as a pressure-sensitive adhesive tape that fixes the pressure-sensitive conductive member on the electrode substrate. Since the pressure-sensitive conductive member used in the present invention expresses pressure-sensitive characteristics by changing the contact area with the electrode, it is essential to fix the pressure-sensitive conductive member on the electrode. Any attachment method may be used as long as the relative positional relationship between the electrode substrate and the pressure-sensitive conductive member does not shift. However, in order to achieve the object of the present invention to suppress the dispersion of pressure-sensitive characteristics due to various pressure forms and to protect the pressure-sensitive conductive member, at least the pressure application surface of the pressure-sensitive conductive member is covered with an insulating coating. It must be covered with a member.

  As an example of the embodiment of covering with an insulating covering member, there are pressure sensitive sensor bodies shown in FIGS. 1 and 2 and FIGS. 3 and 4. 1 and 2, a pressure-sensitive conductive member 3 is disposed on an electrode substrate including a substrate 1 and an electrode 2, and an insulating covering member 4 having a sufficiently large area is covered thereon, and the vicinity of the outer periphery of the insulating covering member. Is attached to the electrode substrate surface, whereby the pressure-sensitive conductive member is fixed on the electrode substrate via the adhesive layer 4b. Further, as shown in FIGS. 3 and 4, there is a method in which the outer peripheral surface of the substrate electrode on which the pressure-sensitive conductive member is disposed is wound with an insulating covering member at least once.

  The pressure-sensitive adhesive layer can be formed, for example, by applying a pressure-sensitive adhesive to at least one surface of the flexible film. As the adhesive applied to the surface of the flexible film, an acrylic adhesive can be preferably used. There are other adhesives such as rubber and silicone rubber as the adhesive, and these can also be used. However, in the rubber-based adhesive, a tackifier or the like is blended in order to obtain adhesiveness. For this reason, the tackifier oozes out in a specific use environment or for a long period of time, causing electric contact failure, or depending on the type of rubber used, the adhesive itself may be cured due to curing, deterioration, etc. There is concern about being lost. In addition, the silicone rubber-based pressure-sensitive adhesive may cause an electrical contact failure due to the leakage of the low molecular siloxane component contained. On the other hand, acrylic ester copolymers, which are the main components, are more suitable for acrylic adhesives because they have adhesiveness and have higher adhesive strength than rubber-based and silicone-based adhesives. Although it does not restrict | limit especially as thickness of an adhesive layer, Generally it uses in the range of 10-50 micrometers.

<Pressure-sensitive conductive member>
As the pressure-sensitive conductive member, a member obtained by laminating a conductive coating layer containing a conductive material on an insulating elastomer sheet can be used. For example, a rubber elastic body is used as the insulating elastomer sheet, and a conductive paint is applied on the surface thereof. The coating layer may be a single layer or two or more layers in order to match desired properties such as adjustment of electric resistance value and surface properties. As thickness, it is apply | coated by 10-50 micrometers of coating layers with respect to 100-1000 micrometers of insulating elastomer sheets. If the coating layer is 10 μm or more, the seepage from the insulating elastomer sheet can be blocked, and contamination of the electrode part which is the contact member can be prevented. Resin components of the conductive paint include fluororesin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene-butylene-olefin copolymer (SEBC), and olefin-ethylene-butylene-olefin copolymer. (CEBC). These resins may be used alone or in combination of two or more. Further, the base resin of the insulating elastomer sheet may be a cross-linked resin, and as a curing agent for this purpose, for example, an isocyanate compound and an amine compound can be appropriately blended.

  As the pressure-sensitive conductive member, a conductive elastomer obtained by dispersing and mixing a conductive material in an elastomer such as rubber or resin can be used so as not to impair the flexibility of the pressure-sensitive sensor body. The elastomer type is not particularly limited as long as it has a Young's modulus smaller than that of the flexible film, but is preferably a rubber elastic body that is excellent in conformity to a shape change due to pressure application or release, that is, excellent in resilience. It is. In general, since the Young's modulus of the rubber elastic body is 0.01 to 0.1 GPa, a conventionally known one can be used, but a butadiene rubber excellent in rebound resilience is particularly preferable. In addition, various rubbers may be blended to obtain desired characteristics. In that case, a blend with natural rubber or isoprene rubber is preferable without impairing the resilience of butadiene rubber.

[Conductive material]
The conductive material blended in the pressure-sensitive conductive member is not particularly limited, and conventionally known materials can be used. For example, conductive carbon oxide, graphite, graphite particles, copper, aluminum, nickel, iron powder, and metal oxides such as conductive tin oxide and conductive titanium oxide can be used. These may be used alone or in combination of two or more. As a compounding quantity, it is 2-200 mass parts with respect to 100 mass parts of rubber | gum or resin used as a base, Preferably it is the range of 5-100 mass parts. In addition to rubber or resin and a conductive material, other components can be blended, and examples thereof include organic elastic fillers and inorganic oxide fillers. Examples of the organic elastic filler include spherical particles made of an elastomer such as silicone or urethane, or a resin such as acrylic, styrene, or polyamide. Examples of the inorganic oxide filler include silica, alumina, titanium oxide, zinc oxide, and magnesium oxide.

  The pressure-sensitive conductive member used in the present invention detects a change in contact area with the electrode substrate as a change in electrical resistance when pressure is applied. In order to control the contact area, the contact surface can be appropriately provided with an uneven shape or roughened. Examples of the method for providing the surface uneven shape include a method in which a desired unevenness is provided in the cavity, or a mold that has been subjected to blasting or the like is filled with an uncured rubber material and cured to transfer. It is done. Further, in the case of a pressure-sensitive conductive member having a coating layer, a method of applying a conductive paint to the insulating elastomer sheet having concavo-convex transferred as described above, or roughening particles in the conductive paint, acrylic, styrene, Examples thereof include a method of adding spherical particles made of a resin such as polyamide.

<Electrode substrate>
A known electrode substrate can be used as the electrode substrate. For example, a pattern may be formed by printing copper foil or the like on an insulating substrate such as a glass epoxy substrate, or an insulating film such as polyamide may be combined with a conductor such as copper foil as in a flexible printed substrate. . In addition, in order to reduce the size and flexibility of the pressure-sensitive sensor, it is possible to use a screen-printed conductive paste containing silver or carbon black on a polyamide or polyethylene terephthalate (PET) insulating film in an arbitrary pattern. good.

<Wiring section>
A known wiring type can be used as the wiring portion. For example, there is a method of drawing out a lead wire from a desired position on a substrate on which a pattern of a conductive portion is printed as described above. Moreover, when using an insulating film as a board | substrate, when providing the pattern of an electrode part, what also printed the conductive path used as a wiring part simultaneously can also be used.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

[Example 1]
<1. Creation of pressure-sensitive conductive member>
The materials shown in Table 1 were prepared. Using a 3L pressure type kneader (D3-10: manufactured by Moriyama Co., Ltd.), first masticating only the raw rubber for 1 minute at a rotor speed of 30 rpm, and then adding zinc oxide, zinc stearate and carbon black for 10 minutes Kneaded. The filling amount of the material with respect to the kneader capacity was 65% by volume. After cooling the obtained rubber composition at room temperature (25 ° C.) for 1 hour, using an open roll machine (12-inch test roll machine: manufactured by Kansai Roll Co., Ltd.), add TETD, MBTS and sulfur. And kneaded. After kneading for 15 minutes with a front roll of 15 rpm and a back roll of 18 rpm as appropriate, after passing through a roll gap of 0.6 mm, it is cut into a size of 10 mm in length and 10 mm in width to form a rubber composition as a base material. An unvulcanized product was obtained. Next, this unvulcanized product was filled in a 10 mm long, 10 mm wide, 0.5 mm deep mold preheated to 170 ° C., and press vulcanized at 170 ° C. and 100 kgf for 15 minutes to obtain rubber elasticity. Got the body.

  On the other hand, the materials shown in Table 2 were stirred using a mixer to prepare a mixed solution 1. Next, this mixed solution was used as a medium with glass beads having an average particle diameter of 0.8 mm, and a bead mill disperser (Ultra Visco Mill, manufactured by IMEX Co., Ltd.) filled at a filling rate of 80% with respect to the volume of the container. A primary dispersion was prepared by carrying out a circulation operation for 6 hours at a disk peripheral speed of 10 m / s and a processing speed of 200 ml / min, followed by dispersion treatment.

  Subsequently, the material shown in Table 3 containing 452 parts by mass of the primary dispersion liquid was stirred using a mixer to prepare a mixed solution 2. Next, this mixed solution was subjected to a disk using a bead mill disperser (made by IMEX, Ultra Visco Mill) filled with glass beads having an average particle diameter of 0.8 mm as a medium at a filling rate of 80% with respect to the volume of the container. Circulation operation was performed for 2 hours at a peripheral speed of 6 m / s and a processing speed of 600 ml / min, and dispersion treatment was performed to prepare a secondary dispersion.

  This secondary dispersion solution is applied to the rubber elastic body (length 10 mm, width 10 mm, thickness 0.5 mm) by the dipping method and cured by heating at 160 ° C. for 60 minutes, and the film thickness is 15 μm. A coating film was formed to obtain a pressure-sensitive conductive member.

<2. Creation of insulating covering member>
A polyimide film (manufactured by Toray DuPont, Kapton 100H / V, Young's modulus 3.4 GPa, thickness 25 μm) was used as the flexible film. An acrylic pressure-sensitive adhesive (Olivein BPS-5127, manufactured by Toyo Ink Chemical Co., Ltd.) is applied to one side of this film by a gravure roll method to form a coating film, which is dried to provide an insulating layer having a pressure-sensitive adhesive layer having a thickness of 15 μm. A coated member was obtained.

<3. Creation of pressure-sensitive sensor body>
The pressure-sensitive conductive member (length 10 mm, width 10 mm) was placed on a comb-like test electrode (outer dimensions: length 15 mm, width 15 mm, electrode size: length 10 mm, width 10 mm) shown in FIG. Next, the insulating covering member is cut into a size of 15 mm in length and 15 mm in width, and pasted on the electrode as shown in FIGS. 1 and 2, whereby the pressure-sensitive conductive member is fixed on the electrode. Got.

<4. Evaluation method>
The obtained pressure-sensitive sensor body was evaluated after being left in an environment of 23 ° C. and 60% RH for 24 hours or more. For the measurement, a pressure-sensitive characteristic evaluation apparatus shown in FIG. 6 was used, and a load was applied from above the fixed pressure-sensitive sensor body with a cylindrical pusher having a diameter of 3 mm. At that time, a voltage of 5 V was applied to the pressure sensor body, and the electrical resistance value of the pressure sensor body was calculated from the voltage applied to the internal resistance 1 kΩ connected in series with the pressure sensor body.

[4-1. (Variation evaluation)
A load of 100 kPa was applied to each of the points 1 to 5 shown in FIG. 7 using the pressure-sensitive characteristic evaluation apparatus, and evaluation was performed from variations in the electric resistance values of the pressure-sensitive sensor bodies at that time. Each measurement point 1, 2, 3, 4, and R ₁ an electric resistance value of the pressure sensor body in _{5, R 2, R 3,} R 4, and R _5, logR _1, logR ₂ each logarithmic values, The logR ₃ , logR ₄ , and logR ₅ were ranked according to the following criteria.

[4-1. Sensor sensitivity evaluation)
Using the pressure sensitive characteristic evaluation apparatus described above, a load is applied in the range of 0 kPa to 500 kPa to the locations 1 to 5 shown in FIG. 7, and the average value of the resistance values of the pressure sensitive sensor body shown at 0 kPa and 500 kPa is applied. The difference in the average value of the resistance values of the pressure-sensitive sensor bodies indicated at times was defined as sensor sensitivity and ranked according to the following criteria.

  As a comprehensive evaluation, when the variation evaluation and the sensor sensitivity evaluation are both A, the rank is A, A and B or both B are B rank, and at least one is C rank is C rank did. The evaluation results are shown in Table 5.

[Examples 2 to 7 and Comparative Examples 1 to 4]
A pressure-sensitive sensor body was produced in the same manner as in Example 1 except that an insulating covering member provided with an adhesive layer was produced in the same manner as in Example 1 using the film shown in Table 4 as a flexible film. And evaluated. The evaluation results are shown in Table 5.

  The change of the electrical resistance value of the pressure-sensitive sensor body with respect to the load in Examples 1 and 2 and Comparative Examples 1 and 2 is shown in FIGS. These Examples and Comparative Examples are examples using films having the same thickness but different Young's moduli. In contrast to Examples 1 and 2, in Comparative Example 1, the Young's modulus (rigidity) of the insulating covering member is too small, so when a load is applied locally, a slight difference in effective contact area depending on the load bias and location However, it can be seen that variations appear in the electric resistance value. Thus, it can be said that when the Young's modulus of the insulating covering member decreases, the electric resistance value of the pressure-sensitive sensor body tends to vary. Moreover, since the Young's modulus is too large in Comparative Example 2, when pasting so as to cover the entire surface of the pressure-sensitive conductive member, a load is always applied to the pressure-sensitive conductive member by the insulating covering member. Even at 0 kPa, the electric resistance value decreases, and the difference from the electric resistance value when a load of 500 kPa is applied becomes small. That is, it can be said that the sensitivity as a sensor tends to decrease as the Young's modulus increases. From the above results and Examples 3 and 4, the appropriate Young's modulus of the insulating covering member used for the pressure-sensitive sensor body of the present invention is 1.7 GPa or more and 6.5 GPa or less, more preferably 3.0 GPa. The above is 4.0 GPa or less.

  Examples 2, 5, 6, and 7 and Comparative Examples 3 and 4 are films having the same Young's modulus with different thicknesses. As in Comparative Example 3, the electrical resistance value of the pressure-sensitive sensor body tends to vary as the thickness decreases, and the sensitivity as the pressure-sensitive sensor body decreases as the thickness increases, and it becomes difficult to attach and fix itself. I understand that. In the case of the comparative example 4, since the film thickness was too large, the insulating coating member could not be stuck on the electrode substrate. From the above results, the appropriate film thickness of the insulating covering member used in the pressure-sensitive sensor body of the present invention is 10 μm or more and 100 μm or less, and more preferably 25 μm or more and 75 μm or less.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Electrode 3 Pressure sensitive conductive member 4 Insulating coating | coated member 4a Flexible film 4b Adhesive layer 5 Wiring part 6 Load measuring instrument 7 Cylindrical presser 8 Pressure sensor 9 Voltage measuring instrument 10 1kohm internal resistor 11 Voltage application device

Claims (5)

  An electrode substrate having at least a pair of electrodes on the substrate, a pressure-sensitive conductive member whose electrical resistance value changes due to a change in contact area between the electrode substrate and the electrode substrate when subjected to pressure, and at least the pressure-sensitive conductive member In a pressure-sensitive sensor body having at least an insulating covering member that covers a pressure application surface and a wiring portion respectively connected to the electrode, the insulating covering member includes an adhesive layer, a Young's modulus of 1.7 GPa. At least 6.5 GPa and a flexible film having a thickness of 10 μm or more and 100 μm or less, and the pressure-sensitive conductive member is fixed on the electrode substrate by the adhesive layer being attached to the electrode substrate. A pressure-sensitive sensor body.   2. The pressure-sensitive sensor body according to claim 1, wherein the flexible film has a Young's modulus of 3.0 GPa to 4.0 GPa and a thickness of 25 μm to 75 μm.   The pressure-sensitive sensor body according to claim 1 or 2, wherein the pressure-sensitive adhesive of the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive.   The pressure-sensitive conductive member according to any one of claims 1 to 3, wherein the pressure-sensitive conductive member is formed by laminating a conductive coating layer containing a conductive material on an insulating elastomer sheet. Sensor body.   The pressure-sensitive sensor body according to any one of claims 1 to 3, wherein the pressure-sensitive conductive member is a conductive elastomer containing a conductive material.