Sensor sheet and sensor sheet manufacturing method

Abstract

A sensor sheet (18) is provided with: an insulating sheet (24) having a first surface (27) and a second surface (28); a conductive first electrode sheet (25) that is disposed on the first surface (27) side of the insulating sheet (24) and has a through first opening (34a); a first joining part (36) that joins the insulating sheet (24) and the first electrode sheet (25); a conductive second electrode sheet (26) that is disposed on the second surface (28) side of the insulating sheet (24) and that has a through second opening (34b); and a second bonding portion (37) that bonds the insulating sheet (24) and the second electrode sheet (26), the sensor sheet (18) being configured so that, in a stress-strain curve in a tensile test, the sensor sheet (18) does not have a yield point exhibiting a maximum value in a strain range of 0.5-10%, the aperture ratio, which is the ratio of the aperture area of the first aperture portion (34a) to the area of the first electrode sheet, is 1-50%, and the aperture ratio is 1-50%. The aperture ratio, which is the ratio of the opening area of the second opening (34b) to the area of the second electrode sheet (26), is 1% or more and 50% or less.

Description

Technical Field

[0001] The present invention relates to a sensor sheet and a method for manufacturing the sensor sheet. Background Art

[0002] A sensor sheet including a dielectric layer and a first electrode sheet disposed on a first surface of the dielectric layer is disclosed in Patent Document 1. The sensor sheet is mounted on, for example, a steering wheel of a vehicle to detect whether a passenger is in contact with the steering wheel.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-68414 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the sensor sheet described in Patent Document 1, there is a problem with the reliability of the detection accuracy of the sensor. For example, when the sensor sheet is assembled to a steering wheel, since the sensor sheet is stretched and elongated while being wound around the steering wheel, there is a problem that the conduction path of the first electrode sheet changes due to the tensile stress and the resistance value of the first electrode sheet changes.

[0008] The present invention has been made in view of this background, and an object thereof is to provide a sensor sheet and a method for manufacturing the sensor sheet in which a change in resistance value is suppressed.

[0009] Means for Solving the Problems

[0010] One aspect of the present invention is a sensor sheet, wherein

[0011] the sensor sheet includes:

[0012] an insulating sheet having a first surface and a second surface, formed of a foam;

[0013] a conductive first electrode sheet disposed on the first surface side of the insulating sheet and having a first through-opening;

[0014] a first joint portion that joints the insulating sheet and the first electrode sheet;

[0015] a conductive second electrode sheet disposed on the second surface side of the insulating sheet and having a second through-opening; and

[0016] a second joint portion that joints the insulating sheet and the second electrode sheet,

[0017] the first electrode sheet and the second electrode sheet are conductive cloths formed by weaving a plurality of fibril aggregates

[0018] The plurality of fibril aggregates include a plurality of fibrils and a coating formed on at least a part of the surface of the fibrils.

[0019] The first electrode sheet has the first opening portion that opens between the plurality of fibril aggregates.

[0020] The second electrode sheet has a second opening portion that opens between the plurality of fibril aggregates.

[0021] The sensor sheet is configured such that in a stress-strain curve in a tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%.

[0022] The ratio of the opening area of the first opening portion to the area of the first electrode sheet, that is, the opening ratio, is 1% or more and 50% or less.

[0023] The ratio of the opening area of the second opening portion to the area of the second electrode sheet, that is, the opening ratio, is 1% or more and 50% or less.

[0024] Another aspect of the present invention is a method for manufacturing a sensor sheet, wherein

[0025] The method for manufacturing the sensor sheet includes:

[0026] A step of forming a fibril aggregate by gathering a plurality of fibrils;

[0027] A step of forming a base fabric by weaving a plurality of the fibril aggregates;

[0028] A step of forming a conductive fabric by plating the base fabric; and

[0029] A step of forming a sensor sheet by bonding the conductive fabric to the first surface of an elastic insulating sheet having a first surface and a second surface.

[0030] Advantageous Effects of the Invention

[0031] According to one aspect of the present invention, when a tensile force is applied to the sensor sheet, the first opening portion of the first electrode sheet and the second opening portion of the second electrode sheet are deformed in such a manner that the opening areas of the first opening portion and the second opening portion are reduced. Then, new conductive paths are formed between the plurality of fibril aggregates separated by the first opening portion. Similarly, new conductive paths are formed between the plurality of fibril aggregates separated by the second opening portion. Thus, even when a tensile force is applied to the sensor sheet, a change in the resistance value can be suppressed.

[0032] In addition, the sensor sheet according to one embodiment of the present invention is configured such that in the stress-strain curve in the tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%. Thereby, it is possible to suppress the fracture of the coating layer in the strain range of 0.5 to 10%, and thus it is possible to suppress the change in the resistance value of the sensor sheet.

[0033] In addition, according to another embodiment of the present invention, there are cases where the coating layers formed on the surfaces of adjacent filaments are electrically connected by contacting each other, and cases where no coating layer is formed on the surfaces of adjacent filaments and they can move freely relative to each other. Thereby, when a tensile force is applied to the sensor sheet, the stress is absorbed by the filaments that can move freely relative to each other, and thus it is possible to suppress the application of excessive stress to the sensor sheet. As a result, the electrical connection of the sensor sheet is maintained by the filaments that are electrically connected to each other, and thus it is possible to suppress the change in the resistance value of the sensor sheet.

[0034] It should be noted that the reference numerals in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a front view of a steering wheel equipped with the sensor sheet of Embodiment 1-1.

[0036] Figure 2 is Figure 1 a cross-sectional view taken along line A-A of

[0037] Figure 3 is a top view of the sensor sheet of Embodiment 1-1.

[0038] Figure 4 is Figure 3 a cross-sectional view taken along line B-B of

[0039] Figure 5 In (a) of Figure 5 is a partially enlarged top view of the first electrode sheet of Example 1-1,

[0040] Figure 6 is Figure 5 a cross-sectional view taken along line C-C of (a) of

[0041] Figure 7 is a partially enlarged top view of the first electrode sheet of Example 1-1.

[0042] Figure 8 is a cross-sectional view of the warp filament aggregate of Example 1-1.

[0043] Fig. 9 Among them, (a) is a partially enlarged top view of the first electrode sheet of Example 1-2. Fig. 9 Among them, (b) is a partially enlarged top view of the second electrode sheet of Example 1-2.

[0044] Fig.10 Among them, (a) is a partially enlarged top view of the first electrode sheet of Comparative Example 1-1. Fig.10 Among them, (b) is a partially enlarged top view of the second electrode sheet of Comparative Example 1-1.

[0045] Fig.11 It is a graph showing the relationship between stress and strain in the tensile test for the first electrode sheet.

[0046] Fig.12 It is a graph showing the relationship between stress and strain in the tensile test for the sensor sheet.

[0047] Fig.13 Among them, (a) is a partially enlarged top view of the first electrode sheet with an elongation rate of 0% for Sample 1-2. Fig.13 Among them, (b) is a partially enlarged top view of the first electrode sheet with an elongation rate of 10% for Sample 1-2. Fig.13 Among them, (c) is a partially enlarged top view of the first electrode sheet with an elongation rate of 20% for Sample 1-2. Fig.13 Among them, (d) is a partially enlarged top view of the first electrode sheet with an elongation rate of 30% for Sample 1-2.

[0048] Fig.14 It is a graph showing the relationship between the change rate of the DC resistance value of the sensor sheet and strain.

[0049] Fig.15 It is a graph showing the relationship between the change rate of the DC resistance value and the number of repetitions in the case where a 10% elongation tensile test is repeatedly performed on the sensor sheet.

[0050] Fig.16 It is a graph showing the relationship between the change rate of the DC resistance value and the number of repetitions in the case where a 20% elongation tensile test is repeatedly performed on the sensor sheet.

[0051] Fig.17 It is the first electrode sheet of the modified example of Example 1-2 and Figure 5 The cross-sectional view corresponding to the C-C line of (a) among them.

[0052] Fig.18 It is the first electrode sheet of Modified Example 2 of Example 1-2 and Figure 5 The cross-sectional view corresponding to the C-C line of (a) among them.

[0053] Fig.19 Among them, (a) is a partially enlarged top view showing the first electrode sheet of Embodiment 2-1. Fig.19 Among them, (b) is a partially enlarged top view showing the second electrode sheet of Embodiment 2-1.

[0054] Fig. 20 is Fig.19 a sectional view taken along line C-C of

[0055] Fig.21 Among them, (a) is a partially enlarged top view showing the first electrode sheet of Embodiment 2-2. Fig.21 Among them, (b) is a partially enlarged top view showing the second electrode sheet of Embodiment 2-2.

[0056] Fig. 22 is Fig.21 a sectional view taken along line D-D of

[0057] Fig.23 is a sectional view corresponding to the D-D line of the first electrode sheet of Variation (1) of Embodiment 2-2 and Fig.21

[0058] Fig.24 is a sectional view corresponding to the D-D line of the first electrode sheet of Variation (2) of Embodiment 2-2 and Fig.21

[0059] Fig.25 Among them, (a) is a partially enlarged top view showing the first electrode sheet of Comparative Example 2-1. Fig.25 Among them, (b) is a partially enlarged top view showing the second electrode sheet of Comparative Example 2-1.

[0060] Fig.26 is Fig.25 a sectional view taken along line E-E of

[0061] Fig. 27 is a graph showing the relationship between stress and strain in the case where a tensile test is performed on the first electrode sheet.

[0062] Fig.28 is a graph showing the relationship between stress and strain in the case where a tensile test is performed on the sensor sheet.

[0063] Fig.29 is a partially enlarged top view of the first electrode sheet in the case where a tensile test is performed on the sensor sheet according to Embodiment 2-1.

[0064] Fig.30 is a graph showing the relationship between the DC resistance value and strain in the case where a tensile test is performed on the sensor sheet. ​​

[0065] Fig.31 Among them, (a) is a partially enlarged top view showing the first electrode sheet of Example 3-1. Fig.31 Among them, (b) is a partially enlarged top view showing the second electrode sheet of Example 3-1.

[0066] Fig.32 is Fig.31 A cross-sectional view taken along the C-C line of (a) in it.

[0067] Fig.33 It is a partially enlarged top view showing the first electrode sheet of Example 3-1.

[0068] Fig.34 It is a cross-sectional view showing the warp fiber aggregate of the first electrode sheet of Example 3-1.

[0069] Fig.35 Among them, (a) is a partially enlarged top view showing the first electrode sheet of Example 3-2. Fig.35 Among them, (b) is a partially enlarged top view showing the second electrode sheet of Example 3-2.

[0070] Fig.36 Among them, (a) is a partially enlarged top view showing the first electrode sheet of Comparative Example 3-1. Fig.36 Among them, (b) is a partially enlarged top view showing the second electrode sheet of Comparative Example 3-1.

[0071] Fig.37 is Fig.36 A cross-sectional view taken along the D-D line of it.

[0072] Fig.38 It is a graph showing the relationship between stress and strain in the tensile test of the first electrode sheet.

[0073] Fig.39 It is a graph showing the relationship between stress and strain in the tensile test of the sensor sheet.

[0074] Fig.40 Among them, (a) is a partially enlarged top view of the first electrode sheet with an elongation rate of 0% for Sample 3-2. Fig.40 Among them, (b) is a partially enlarged top view of the first electrode sheet with an elongation rate of 10% for Sample 3-2. Fig.40 Among them, (c) is a partially enlarged top view of the first electrode sheet with an elongation rate of 20% for Sample 3-2. Fig.40 Among them, (d) is a partially enlarged top view of the first electrode sheet with an elongation rate of 30% for Sample 3-2.

[0075] Fig.41It is a graph showing the relationship between the rate of change of the DC resistance value of the sensor chip and the strain.

[0076] Fig.42 It is a graph showing the relationship between the rate of change of the DC resistance value and the number of repetitions in the case where a 10% elongation tensile test is repeatedly performed on the sensor chip.

[0077] Fig.43 It is a graph showing the relationship between the rate of change of the DC resistance value and the number of repetitions in the case where a 20% elongation tensile test is repeatedly performed on the sensor chip.

[0078] Fig.44 It is a partially enlarged top view of the first electrode chip of Embodiment 3-2.

[0079] Fig.45 It is Fig.44 A sectional view taken along line E-E of

[0080] Fig.46 It is Fig.44 A sectional view taken along line F-F of

[0081] Fig.47 It is a top view of the sensor chip of Embodiment 3-2, and is a top view schematically showing the weave eyes of a plurality of warp filament aggregates and a plurality of weft filament aggregates.

[0082] Fig.48 It is a sectional view of the first electrode chip of Embodiment 3-3 corresponding to Fig.44 A sectional view taken along line E-E of

[0083] Fig.49 It is a sectional view of the first electrode chip of Embodiment 3-3 corresponding to Fig.44 A sectional view taken along line F-F of

[0084] Fig.50 It is a partially enlarged top view of the first electrode chip of Embodiment 3-4.

[0085] Fig.51 It is a partially enlarged top view of the first electrode chip of Embodiment 3-5.

[0086] Fig.52 It is a partially enlarged top view of the first electrode chip of Embodiment 3-6.

[0087] Fig.53 It is a partially enlarged top view of the first electrode chip of Embodiment 3-7.

[0088] Fig.54 It is a top view of the sensor chip of Embodiment 3-8.

[0089] Fig.55 is a top view of the sensor sheet showing Embodiments 3-9.

[0090] Fig.56 is a cross-sectional view taken along line B-B of the first electrode sheet according to the modified example, corresponding to Figure 3 .

[0091] Fig.57 is a top view of the sensor sheet showing Embodiment 4-1.

[0092] Fig.58 is Fig.57 a cross-sectional view taken along line B-B.

[0093] Fig.59 In (a) is a partially enlarged top view of the first electrode sheet showing Example 4-1, Fig.59 and in (b) is a partially enlarged top view of the second electrode sheet showing Example 4-1.

[0094] Fig.60 is Fig.59 a cross-sectional view taken along line C-C of (a).

[0095] Fig.61 In (a) is a partially enlarged top view of the first electrode sheet showing Example 4-2, Fig.61 and in (b) is a partially enlarged top view of the second electrode sheet showing Example 4-2.

[0096] Fig.62 is a graph showing the relationship between stress and strain in the tensile test for the first electrode sheet.

[0097] Fig.63 is a graph showing the relationship between stress and strain in the tensile test for the sensor sheet.

[0098] Fig.64 In (a) is a partially enlarged top view of the first electrode sheet of Sample 4-2 with an elongation rate of 0%, Fig.64 in (b) is a partially enlarged top view of the first electrode sheet of Sample 4-2 with an elongation rate of 10%, Fig.64 in (c) is a partially enlarged top view of the first electrode sheet of Sample 4-2 with an elongation rate of 20%, Fig.64 and in (d) is a partially enlarged top view of the first electrode sheet of Sample 4-2 with an elongation rate of 30%.

[0099] Fig.65 is a graph showing the relationship between the change rate of the DC resistance value of the sensor sheet and strain.

[0100] Fig.66It is a graph showing the relationship between the change rate of the DC resistance value and the number of repetitions in the case where a 10% elongation tensile test is repeatedly performed on the sensor sheet.

[0101] Fig.67 It is a graph showing the relationship between the change rate of the DC resistance value and the number of repetitions in the case where a 20% elongation tensile test is repeatedly performed on the sensor sheet.

[0102] Fig.68 In (a) of [], it is a partially enlarged top view of the first electrode sheet showing a modified example of Embodiment 4-1. Fig.68 In (b) of [], it is a partially enlarged top view of the second electrode sheet showing a modified example of Embodiment 4-1.

[0103] Fig.69 It is Fig.67 a cross-sectional view taken along the D-D line of.

[0104] Fig.70 It is a partially enlarged top view of the first electrode sheet in the case where a tensile test is performed on a modified example of Embodiment 4-1.

[0105] Fig.71 It is a cross-sectional view of the sensor sheet according to Embodiment 4-2, corresponding to Fig.57 a cross-sectional view taken along the B-B line of.

[0106] Fig.72 It is a partially enlarged cross-sectional view of the sensor sheet according to Embodiment 4-2.

[0107] Fig.73 It is a cross-sectional view of the sensor sheet according to Embodiment 4-3, corresponding to Fig.57 a cross-sectional view taken along the B-B line of.

[0108] Fig.74 It is a partially enlarged cross-sectional view of the sensor sheet according to Embodiment 4-3.

[0109] Fig.75 It is a cross-sectional view of the sensor sheet according to Embodiment 4-4, corresponding to Fig.57 a cross-sectional view taken along the B-B line of. Specific Embodiments

[0110] (Embodiment 1-1)

[0111] 1.1. Outline of the sensor sheet and the steering wheel

[0112] 1.1.1. Outline of the sensor sheet

[0113] The sensor sheet is of the electrostatic type and functions, for example, as a sensor that detects the contact or approach of a conductive body having a potential by utilizing the change in the electrostatic capacitance between electrodes. When a conductive body having a potential comes into contact with or approaches the sensor sheet, the electrostatic capacitance between the electrodes changes, and the contact or approach of the conductive body is detected by detecting the voltage corresponding to the changed electrostatic capacitance between the electrodes.

[0114] The sensor sheet is mounted, for example, on the steering wheel of a vehicle to detect whether a passenger's hand (fingers, palm, back of the hand, etc.) is in contact with or approaching the steering wheel.

[0115] 1.1.2. Overall Structure of Steering Wheel 10

[0116] First, with reference to Figure 1-2 , the structure of the steering wheel 10 will be described. As shown in Figure 1 , the steering wheel 10 includes a core portion 11, a ring portion 12, and a plurality (three in this embodiment) of connecting portions 13 that connect the core portion 11 and the ring portion 12.

[0117] The ring portion 12 is formed in a circular ring shape. However, the ring portion 12 is not limited to a circular shape and can be formed in any shape. As shown in Figure 2 , the cross-sectional shape of the ring portion 12 perpendicular to the axis is formed in a circular shape, for example.

[0118] 1.1.3. Detailed Structure of Steering Wheel 10

[0119] With reference to Figure 1-2 , the detailed structure of the steering wheel 10 will be described. In particular, the detailed structure of the ring portion 12 will be described.

[0120] The ring portion 12 includes a core body 16, a resin inner layer material 17, a sensor sheet 18, and a skin material 19. The core body 16 forms the central portion of the ring portion 12 and is formed in a shape corresponding to the shape of the ring portion 12. That is, the core body 16 is formed in a circular ring shape and has a circular cross-section perpendicular to the axis. Among them, the cross-sectional shape of the core body 16 perpendicular to the axis is not limited to a circular shape and can be set to any shape such as an oval, an egg shape, a U shape, a C shape, or a polygon. The core body 16 of this embodiment is formed of a metal such as aluminum or magnesium and has conductivity. The material of the core body 16 can be a material other than metal.

[0121] The resin inner layer material 17 covers the outer surface of the core body 16 over the entire circumference of the annular shape of the core body 16 and over the entire circumference of the circular cross-sectional shape of the core body 16. In this embodiment, the cross-section perpendicular to the axis of the resin inner layer material 17 is formed in a circular shape. Assuming that the core body 16 has a U-shaped cross-section perpendicular to the axis, the resin inner layer material 17 not only covers the radially outer side of the cross-section perpendicular to the axis of the core body 16, but also fills into the U-shaped recess of the core body 16. The resin inner layer material 17 is formed on the outer surface side of the core body 16 by injection molding and is directly joined to the outer surface of the core body 16. The cross-sectional shape perpendicular to the axis of the resin inner layer material 17 is not limited to a circular shape, and can be set to any shape such as an oval shape, an elliptical shape, a polygonal shape, etc. The resin inner layer material 17 is formed of a foamed resin, for example. The resin inner layer material 17 uses a foamed urethane resin, for example. It should be noted that a non-foamed resin may also be used for the resin inner layer material 17.

[0122] A sensor sheet 18 is wound around the outer surface of the resin inner layer material 17. The sensor sheet 18 is in a C shape in a state of being wound around the resin inner layer material 17. The sensor sheet 18 will be described in detail later.

[0123] The skin material 19 covers the outer surface of the sensor sheet 18 (the surface of the sensor sheet 18 on the side opposite to the resin inner layer material 17) over the entire circumference of the annular shape of the sensor sheet 18. That is, as will be described later, when the first electrode sheet 25 is exposed on the first surface 27 side of the insulating sheet 24, the skin material 19 also functions as a covering material for the first electrode sheet 25. The skin material 19 is formed by injection molding, is wound around the outer surface side of the sensor sheet 18, and is joined to the outer surface of the sensor sheet 18. The skin material 19 is formed of a urethane resin, for example. The outer surface of the skin material 19 constitutes a design surface. The material of the skin material 19 is not particularly limited, and for example, a non-foamed urethane resin or a slightly foamed urethane resin is preferably used.

[0124] As another embodiment of the skin material 19, it may be configured such that the skin material 19 uses leather or cloth, is wound around the outer surface side of the sensor sheet 18, and is joined to the outer surface of the sensor sheet 18. It may also be configured such that an adhesive material or an adhesive is used for joining the skin material 19 and the sensor sheet 18, and in addition, the skin material 19 is sewn and the periphery of the steering wheel is covered. In addition, the outer surface of the skin material 19 constitutes a design surface. The material of the skin material 19 is not particularly limited, and any material such as leather (natural leather, synthetic leather, etc.), cloth, rubber, resin, etc. can be selected, and the skin material 19 is preferably leather (natural leather, synthetic leather, etc.).

[0125] 1.1.4. Overall structure of the sensor sheet 18

[0126] Refer to Figure 3-4The overall configuration of the sensor chip 18 of Embodiment 1-1 will be described. As Figure 3 shown, the entire sensor chip 18 is formed in a shape that is long in the length direction X. The sensor chip 18 includes a chip main body portion 20 that is integrally formed in a rectangular shape. The chip main body portion 20 includes a pair of long side edges 20a extending in the length direction X and a pair of short side edges 20b extending in a direction intersecting the length direction X. It should be noted that in the following description, the arrow X represents the length direction of the sensor chip 18, the arrow Y represents the intersecting direction intersecting the length direction, and the arrow Z represents the thickness direction of the sensor chip 18.

[0127] On a pair of long side edges 20a of the chip main body portion 20, there are formed chip recessed portions 21 that are recessed inward in the intersecting direction Y intersecting the length direction X. The chip recessed portions 21 are formed at positions on a pair of long side edges 20a of the chip main body portion 20 that include regions overlapping in the intersecting direction Y. However, the chip recessed portions 21 may also be configured to be formed only on one of the pair of long side edges 20a.

[0128] A plurality (four in this embodiment) of chip recessed portions 21 are formed at intervals on one long side edge 20a. However, one chip recessed portion 21 may also be formed on one long side edge 20a. Additionally, two to three or five or more chip recessed portions 21 may be formed on one long side edge 20a.

[0129] On one of the pair of long side edges 20a of the chip main body portion 20, at positions near both ends of the chip main body portion 20 in the length direction X, there are formed chip extension portions 22 that extend from one long side edge 20a in a direction intersecting the length direction X.

[0130] Figure 4 A cross-sectional view showing the sensor chip 18 is presented. The sensor chip 18 includes an insulating sheet 24, a first electrode sheet 25, and a second electrode sheet 26. The first electrode sheet 25 and the second electrode sheet 26 have conductivity and are formed in a layered structure.

[0131] The first electrode sheet 25 is disposed on the first surface 27 side of the insulating sheet 24. Specifically, the first electrode sheet 25 is laminated on the first surface 27 of the insulating sheet 24. The first electrode sheet 25 is formed in a similar shape that is slightly smaller than the insulating sheet 24. As a result, the edge portions of the first surface 27 of the insulating sheet 24 are exposed from the edge portions of the first electrode sheet 25.

[0132] As Figure 3As shown, a recess 30 that is recessed inward in the crossing direction Y is formed at a position in the first electrode sheet 25 corresponding to the sheet recess 21 of the sensor sheet 18. At a position in the first electrode sheet 25 corresponding to the sheet extension 22 of the sensor sheet 18, an extension 31a that extends from the long side edge of the first electrode sheet 25 along the length direction X to the extension direction E1 crossing the length direction X and an extension 31b that extends to the extension direction E2 are formed. Core wires 32a exposed from the end portions of the electric wire 32 are connected to the extension 31a and the extension 31b. The core wires 32a and the extension 31a, the extension 31b are electrically connected by a known method such as welding, brazing, ultrasonic welding, etc. In the following description, when the extension 31a and the extension 31b are not distinguished, they are sometimes referred to as the extension 31.

[0133] As Figure 4 shown, the second electrode sheet 26 is disposed on the second surface 28 side of the insulating sheet 24. Specifically, the second electrode sheet 26 is laminated on the second surface 28 of the insulating sheet 24. The second electrode sheet 26 is formed in a similar shape slightly smaller than the insulating sheet 24. Thus, the edge portions of the second surface 28 of the insulating sheet 24 are exposed from the edge portions of the second electrode sheet 26.

[0134] The first electrode sheet 25 and the second electrode sheet 26 may have the same shape and the same size, or may have a similar shape in which one is slightly larger than the other. In this embodiment, the first electrode sheet 25 and the second electrode sheet 26 have substantially the same configuration.

[0135] It should be noted that since the second electrode sheet 26 has substantially the same configuration as the first electrode sheet 25, the repeated description is sometimes omitted in the following description.

[0136] The insulating sheet 24 has flexibility and is configured to be able to elongate in the plane direction. The insulating sheet 24 can be formed, for example, by containing a foaming resin as a main component, or can be formed by containing an elastomer as a main component. Thus, the insulating sheet 24 is soft.

[0137] When the insulating sheet 24 is formed by containing a foaming resin as a main component, the insulating sheet 24 can be manufactured, for example, from a foam of a resin or an elastomer. The elastomer includes crosslinked rubber and thermoplastic elastomer. For example, in addition to urethane foam, polystyrene foam, polyethylene foam, polypropylene foam, polyolefin foam, EVA (ethylene-vinyl acetate copolymer) foam, PET foam, phenol foam, EPDM (ethylene propylene diene rubber) foam, silicone foam, polyvinyl chloride foam, acrylic foam, polyimide foam, polylactic acid resin foam, melamine foam, polymethacrylimide foam, fluororesin foam, etc. can be cited.

[0138] In the case where the insulating sheet 24 is formed mainly of a thermoplastic material, particularly a thermoplastic elastomer, the insulating sheet 24 can be formed of the thermoplastic elastomer itself, or can be formed mainly of an elastomer obtained by crosslinking the thermoplastic elastomer by heating it as a raw material.

[0139] In addition, the insulating sheet 24 can also contain rubbers, resins, other materials, etc. other than the thermoplastic elastomer. For example, when the insulating sheet 24 contains a rubber such as ethylene-propylene rubber (EPM, EPDM), the flexibility of the insulating sheet 24 is improved. From the viewpoint of improving the flexibility of the insulating sheet 24, a flexibility-imparting component such as a plasticizer can also be contained in the insulating sheet 24. In addition, the insulating sheet 24 can also be constituted mainly of a reactive curable elastomer or a thermosetting elastomer.

[0140] In addition, the insulating sheet 24 is preferably a material with good thermal conductivity. Therefore, a thermoplastic elastomer with a high thermal conductivity can be used for the insulating sheet 24, or a filler capable of increasing the thermal conductivity can be contained. In addition, the insulating sheet 24 can also be configured to have a foamed structure having fine air layers. In addition, the insulating sheet 24 can also be configured to have perforations (regular physical holes typified by holes) and slits (cuts, notches).

[0141] The first electrode sheet 25 is disposed on the first surface 27 of the insulating sheet 24, that is, on the upper surface ( Figure 4 the upper surface) side of the insulating sheet 24, and the second electrode sheet 26 is disposed on the second surface 28 of the insulating sheet 24, that is, on the lower surface ( Figure 4 the lower surface) side of the insulating sheet 24. At least the first electrode sheet 25 constitutes a detection electrode. The first electrode sheet 25 and the second electrode sheet 26 have conductivity. In addition, the first electrode sheet 25 and the second electrode sheet 26 are soft. That is, the first electrode sheet 25 and the second electrode sheet 26 have flexibility and are configured to be able to stretch in the plane direction.

[0142] 1.1.5. Bonding structure of the first electrode sheet 25 and the second electrode sheet 26 to the insulating sheet 24

[0143] As Figure 4 shown, on the first surface 27 side of the insulating sheet 24, the first electrode sheet 25 is bonded by the first bonding portion 36. The material constituting the first bonding portion 36 is not particularly limited, and can be appropriately selected from any materials such as acrylic adhesives, silicone adhesives, urethane adhesives, rubber-based adhesives, etc. In addition, as Figure 4 shown, on the second surface 28 side of the insulating sheet 24, the second electrode sheet 26 is bonded by the first bonding portion 36. The material constituting the second bonding portion 37 is the same as that of the first bonding portion 36, so repeated description is omitted.

[0144] 1.1.6. Composition of the electrode sheet

[0145] Refer to Figure 5 in (a) to Figure 5 in (b) and Fig. 9 in (a) to Fig. 9 in (b), the composition of the electrode sheet will be described. Figure 5 in (a) to Figure 5 the first electrode sheets 25 and 25a shown in (b) in Fig. 9 in (a) to Fig. 9 the second electrode sheets 26 and 26a shown in (b) in are conductive cloths with conductivity. The first electrode sheets 25 and 25a and the second electrode sheets 26 and 26a have conductivity and flexibility. The first electrode sheets 25 and 25a and the second electrode sheets 26 and 26a have stretchability in the length direction X and the cross direction Y.

[0146] The first electrode sheet 25 and the second electrode sheet 26 are conductive cloths woven from a plurality of filament aggregates 72. The filament aggregate 72 includes a plurality of filaments 71 and a plating layer 33 formed on at least a part of the surface of the filaments 71.

[0147] As Figure 5 in (a) to Figure 5 in (b) and Fig. 9 in (a) to Fig. 9 in (b) shown, the first electrode sheets 25 and 25a and the second electrode sheets 26 and 26a are manufactured by forming a plating layer 33 on a base cloth woven from a plurality of non-twisted yarn bundles 74. Each non-twisted yarn bundle 74 is formed by gathering a plurality of filaments 71 in an untwisted state.

[0148] Examples of the resin constituting the filaments 71 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyamides such as nylon 6 and nylon 66. However, the resin constituting the filaments 71 is not limited to the above, and any resin can be appropriately selected. The second electrode sheet 26 also has the same composition.

[0149] The method of forming the plating layer 33 is not particularly limited. For example, it can be electroplating, non-electroplating, electroplating can be performed after non-electroplating, or non-electroplating can be performed after electroplating, and any method can be appropriately selected.

[0150] As the metal constituting the coating layer 33 formed on the surface of the base fabric, any metal or alloy such as copper, nickel, tin, solder, etc. can be appropriately selected. The coating layer 33 formed on the surface of the base fabric can be composed of one metal or multiple metals. For example, only copper can be plated on the surface of the base fabric, only nickel can be plated on the surface of the base fabric, or a copper plating layer composed of copper can be formed on the surface of the base fabric, and a nickel plating layer composed of nickel can be formed on the surface of the copper plating layer. The coating layer 33 formed on the surface of the base fabric can be formed by electroplating or electroless plating. The second electrode sheet 26 also has the same structure.

[0151] As Figure 5 shown in (a) of Fig. 9 and (a) of

[0152] As Figure 5 shown in (b) of Fig. 9 and (b) of

[0153] 1.1.7. Examples, Comparative Examples, and Samples

[0154] 1.1.7.1. Example 1-1 and Sample 1-1

[0155] (Example 1-1 and Sample 1-1)

[0156] Refer to Figures 5 to 8 , and Example 1-1 will be described. As Figure 5 shown in (a) of

[0157] The first electrode sheet 25 involved in this Example 1-1 is formed in the following manner: A base fabric is formed by weaving a warp formed by gathering a plurality of filaments 71 in an untwisted state and a weft formed by gathering a plurality of filaments 71 in an untwisted state, and a plating layer 33 is formed on the surface of the base fabric. However, the manufacturing method of the first electrode sheet 25 is not limited to the above method.

[0158] As Figure 5 shown in (a) of [reference], the first electrode sheet 25 of this embodiment includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The first electrode sheet 25 has a first opening 34a that opens between the plurality of filament aggregates 72. The first opening 34a penetrates the first electrode sheet 25. In this Example 1-1, the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25 to the area of the first electrode sheet 25, that is, the opening ratio, is approximately 3%. It should be noted that this opening ratio is the ratio of the total opening area of the plurality of first openings 34a in the target area formed in the first electrode sheet 25 to the area of the target area of the first electrode sheet 25. This opening ratio is calculated, for example, by determining a 10 mm × 10 mm target area in the first electrode sheet 25, summing the areas of the first openings 34a within the target area, and dividing the total area by the area of the target area.

[0159] As Figure 5 shown in (b) of [reference], the second electrode sheet 26 of this embodiment includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The second electrode sheet 26 of this embodiment has a second opening 34b that opens between the plurality of filament aggregates 72. The second opening 34b penetrates the second electrode sheet 26. In this Example 1-1, the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26 to the area of the second electrode sheet 26 of this embodiment, that is, the opening ratio, is approximately 3%.

[0160] There is no particular limitation on the number of filaments 71 included in the filament aggregate 72 that constitutes the first electrode sheet 25. The filament aggregate 72 involved in this embodiment has 75 filaments 71, but it can be set to any number.

[0161] As Figure 6 shown, a plating layer 33 is formed on at least a part of the surface of the twisted yarn 73 that constitutes the filament aggregate 72. By bringing the plating layer 33 of the warp filament aggregate 72a into contact with the plating layer 33 of the weft filament aggregate 72b, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected.

[0162] As Figure 5As shown in (a) in [description], the longitudinal direction S of the plurality of warp filament aggregates 72a is arranged to cross the longitudinal direction X of the first electrode sheet 25. In addition, the longitudinal direction T of the plurality of weft filament aggregates 72b is arranged to cross the longitudinal direction X of the first electrode sheet 25. Specifically, the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode sheet 25 is substantially 45°. In addition, the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode sheet 25a is substantially 45°. The angle being substantially 45° means including the case of 45° and also including cases that can be recognized as substantially 45°.

[0163] When the longitudinal direction S of the warp 41 is parallel to the longitudinal direction X of the first electrode sheet 25 (when the acute angle is substantially 0°), if the first electrode sheet 25 is stretched parallel to the direction X, the warp 41 itself will be stretched, and a large load is required.

[0164] On the other hand, when the longitudinal direction S of the warp 41 is inclined 45° with respect to the longitudinal direction X of the first electrode sheet 25 (when the acute angle is substantially 45°), if the first electrode sheet 25 is stretched parallel to the longitudinal direction X, the square or rectangular lattice formed by the weft 42 and the warp 41 is deformed into a rhombus shape, and the warp 41 or the weft 42 itself will not be stretched, so a large load is not required. That is, when the acute angle is substantially 45°, structural flexibility is imparted. In addition, the higher the aperture ratio, the easier it is for the square or rectangular lattice to be deformed into a rhombus shape, and the structural flexibility is not easily impaired.

[0165] However, it may be that the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode sheet 25 is an angle different from 45°. In addition, it may be that the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode sheet 25 is an angle different from 45°.

[0166] The number of the plurality of filaments 71 constituting the warp filament aggregate 72a and the number of the plurality of filaments 71 constituting the weft filament aggregate 72b may be the same or different. In the present Embodiment 1-1, the number of the plurality of filaments 71 constituting the warp filament aggregate 72a and the number of the plurality of filaments 71 constituting the weft filament aggregate 72b are set to be substantially the same. Substantially the same includes the case of being the same and also includes cases that can be recognized as substantially the same even when they are not the same. The weft filament aggregate 72b is the same as above, so the repeated description is omitted.

[0167] As Figure 6As shown, the warp filament aggregate 72a is composed of a plurality of filaments 71. The warp filament aggregate 72a has an internal space 80 formed in at least a part between adjacent filaments 71. The plurality of filaments 71 are respectively arranged along the plane direction of the sheet surface of the first electrode sheet 25 and the normal direction of the sheet surface.

[0168] The internal space 80 is formed in at least a part between adjacent filaments 71 in the plane direction of the sheet surface of the first electrode sheet 25 and at least a part between adjacent filaments 71 in the normal direction of the sheet surface of the first electrode sheet 25. However, the internal space 80 may be formed only in at least a part between adjacent filaments 71 in the plane direction of the sheet surface of the first electrode sheet 25, or may be formed only in at least a part between adjacent filaments 71 in the normal direction of the sheet surface of the first electrode sheet 25.

[0169] A plating layer 33 is formed on at least a part of the surface of the filament 71 that is exposed in the internal space 80. The surface of the filament 71 is exposed at a part of the surface of the filament 71 that is exposed in the internal space 80 and on which the plating layer 33 is not formed.

[0170] As Figure 6 shown, a plating layer 33 is formed on at least a part of the non-exposed part 81 where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other in an opposed manner. On the other hand, the surface of the filament 71 is exposed at a part of the surface of the filament 71 that is exposed in the non-exposed part 81 and on which the plating layer 33 is not formed.

[0171] At the part where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other, a plating layer 33 is formed on at least a part of the part where the filament 71 exposed on the outer surface of the warp filament aggregate 72a faces the filament exposed on the outer surface of the weft filament aggregate 72b, and the outer surface of the filament 71 is exposed at the part where the plating layer 33 is not formed.

[0172] At the part where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other in an opposed manner, the plating layer 33 is locally formed, and the surface of the filament 71 is exposed at the part where the plating layer 33 is not formed. In the part where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other in an opposed manner, the plating layer 33 is formed in the region close to the part exposed to the outside. On the other hand, in the part close to the inside, the part where the plating layer 33 is formed and the part where the plating layer 33 is not formed coexist.

[0173] Figure 8 The cross-sectional area A1 of each of the warp filament aggregates 72a shown is larger than Figure 7The opening area A2 of the first opening portion 34a is large in a state where the first electrode piece 25 shown does not generate strain. The cross-sectional area A1 of the warp filament aggregate 72a refers to the cross-sectional area formed by the outer contour line of the warp filament aggregate 72a. Hereinafter, the same applies to the weft filament aggregate 72b. Although not shown in detail, the cross-sectional area A1 of each of the weft filament aggregates 72b is larger than the opening area A2 of the first opening portion 34a in a state where the first electrode piece 25 does not generate strain. Although not shown in detail, in the second electrode piece 26, the cross-sectional area A1 of each of the warp filament aggregates 72a and the cross-sectional area A1 of each of the weft filament aggregates 72b are larger than the opening area A2 of the second opening portion 34b in a state where the second electrode piece 26 does not generate strain.

[0174] From Figure 7 When viewed from the thickness direction of the first electrode piece 25 shown, the cross-sectional area A3 of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other is larger than Figure 7 the opening area A2 of the first opening portion 34a shown. Although not shown in detail, when viewed from the thickness direction of the second electrode piece 26, the cross-sectional area A3 of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other is larger than the opening area A2 of the second opening portion 34b.

[0175] The weft filament aggregate 72b is the same as above, so the repeated description is omitted.

[0176] In the present Embodiment 1-1, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is about 10 μm. The metal constituting the coating layer 33 is formed in a three-layer structure, with Ni on the outermost layer, Cu in the middle layer, and Ni on the innermost layer (on the side of the filament 71). The diameter of the warp filament aggregate 72a is about 185 μm, and the diameter of the weft filament aggregate 72b is about 185 μm.

[0177] As Figure 4 shown, the above-mentioned first electrode piece 25 is joined to the first surface 27 of the insulating sheet 24 via the first joining portion 36. In addition, a second electrode piece 26 having the same configuration as the first electrode piece 25 is joined to the second surface 28 of the insulating sheet 24 via the second joining portion 37. The insulating sheet 24 is an ether-based polyurethane foam. The first joining portion 36 is an acrylic adhesive manufactured by NOGAWACHEMICAL Co., Ltd. The thickness of the first joining portion 36 is 50 μm. The first joining portion 36 is the same as the second joining portion 37, so the repeated description is omitted. In this way, a sample 1 of the sensor sheet 18 related to the first electrode piece 25 and the second electrode piece 26b of Example 1-1 is manufactured.

[0178] 1.1.7.2. Example 1-2 and Samples 1-2

[0179] (Example 1-2 and Samples 1-2)

[0180] Next, referring to Fig. 9 in (a) to Fig. 9 in (b), the constitution of the first electrode sheet 25a and the second electrode sheet 26a related to Example 1-2 will be described. In Example 1-2, the number of filaments 71 constituting the warp filament aggregate 72a is different from the number of filaments 71 constituting the weft filament aggregate 72b. In Example 1-2, the number of filaments 71 constituting the warp filament aggregate 72a is more than the number of filaments 71 constituting the weft filament aggregate 72b. However, it can also be configured such that the number of filaments 71 constituting the warp filament aggregate 72a is less than the number of filaments 71 constituting the weft filament aggregate 72b.

[0181] In Example 1-2, the number of filaments 71 constituting the warp filament aggregate 72a is set to about twice the number of filaments 71 constituting the weft filament aggregate 72b. However, the difference between the number of filaments 71 constituting the warp filament aggregate 72a and the number of filaments 71 constituting the weft filament aggregate 72b is not limited to the above.

[0182] The second electrode sheet 26a has the same constitution as the first electrode sheet 25a, so the repeated description will be omitted.

[0183] In Example 1-2, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is about 10 μm. The metal constituting the plating layer 33 is a Ni monolayer. The diameter of the warp filament aggregate 72a is about 180 μm, and the diameter of the weft filament aggregate 72b is about 90 μm.

[0184] The constitution other than the above is the same as that of Example 1-1, so the repeated description will be omitted.

[0185] In addition, in Sample 1-2, the insulating sheet 24 is an ether-based polyurethane foam. The first joint portion 36 is an acrylic-based adhesive. The thickness of the first joint portion 36 is about 50 μm. The first joint portion 36 is the same as the second joint portion 37, so the repeated description will be omitted. Except for the above, the sample 1-2 of the sensor sheet 18 related to the first electrode sheet 25a and the second electrode sheet 26a of Example 1-2 is manufactured in the same manner as Sample 1-1. The description repeated with Sample 1-1 will be omitted.

[0186] 1.1.7.3. Comparative Example 1-1 and Samples 1-3

[0187] (Comparative Example 1-1 and Samples 1-3)

[0188] Next, with reference to Fig.10 (a) to Fig.10 (b) in, Comparative Example 1-1 will be described. The warp filament aggregate 72a and the weft filament aggregate 72b involved in Comparative Example 1-1 each have six filaments 71.

[0189] As Fig.10 (a) shows, the first electrode sheet 25b of this embodiment has a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The first electrode sheet 25b has a first opening portion 34a that opens between the plurality of filament aggregates 72. The first opening portion 34a penetrates the first electrode sheet 25b. In this Comparative Example 1-1, the opening ratio, which is the ratio of the opening area of the first opening portion 34a formed in the first electrode sheet 25b to the area of the first electrode sheet 25b, is 20%.

[0190] As Fig.10 (b) shows, the second electrode sheet 26b of this embodiment has a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The second electrode sheet 26b of this embodiment has a second opening portion 34b that opens between the plurality of filament aggregates 72. The second opening portion 34b penetrates the second electrode sheet 26b. In this Comparative Example 1-1, the opening ratio, which is the ratio of the opening area of the second opening portion 34b formed in the second electrode sheet 26b to the area of the second electrode sheet 26 of this embodiment, is 20%.

[0191] In this Comparative Example 1-1, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is 10 to 20 μm. The metal constituting the coating layer 33 is formed in a three-layer structure, with Ni on the outermost layer, Cu in the middle layer, and Ni on the innermost layer (on the side of the filament 71). The diameter of the warp filament aggregate 72a is about 70 μm, and the diameter of the weft filament aggregate 72b is about 70 μm.

[0192] The constitution other than the above is the same as that of Embodiment 1-1, so repeated descriptions are omitted.

[0193] In addition, in this Comparative Example 1-1, the insulating sheet 24 is an ether-based polyurethane foam. The first joint portion 36 is an acrylic adhesive manufactured by NOGAWA CHEMICAL Co., Ltd. The thickness of the first joint portion 36 is 50 μm. The first joint portion 36 is the same as the second joint portion 37, so repeated descriptions are omitted. Similar to Sample 1-1, Sample 1-3 of the sensor sheet 18 related to the first electrode sheet 25b and the second electrode sheet 26b of Sample 1-3 was fabricated. Descriptions repeated with Sample 1-1 are omitted.

[0194] 1.1.7.4. Tensile Test of the First Electrode Sheet

[0195] Next, refer to Fig.11 , the tensile test performed on the first electrode sheet is described. The first electrode sheet involved in Examples 1-1 to 1-2 and Comparative Example 1-1 is cut into strips of 150 mm × 20 mm to make test pieces. The thickness of the first electrode sheet is different in Examples 1-1 to 1-2 and Comparative Example 1-1, but is about 0.1 mm. The angle between the length direction of the test piece and the length direction of the warp filament assembly 72a is set to 45°.

[0196] The test piece was held by a pair of chucks. The distance between the pair of chucks was 70 mm. The test piece was subjected to a tensile test at a tensile speed of 1 mm / sec, and the stress was calculated by dividing the load by the cross-sectional area of ​​the test piece. The tensile test machine was AGS-X 1kN manufactured by Shimadzu Corporation. The tensile test was carried out within the strain range of 0 to 20%. Fig.11 It is a graph showing the change in stress with respect to strain.

[0197] In Examples 1-1 and 1-2, the stress increases slowly and monotonically in the region of strain 0 to 20%. In the stress-strain curves in the tensile test of Examples 1-1 and 1-2, there is no yield point showing a maximum value in the region of strain 0.5 to 10%.

[0198] Example 1-1 shows a stress of about 1.4 MPa when the strain is 5%, and shows a stress of about 7.5 MPa when the strain is 20%. Example 1-2 shows a stress of about 0.9 MPa when the strain is 5%, and shows a stress of about 5.9 MPa when the strain is 20%. The maximum value of the stress of the sample embodiment and the first electrode sheet 25 and the first electrode sheet 25a involved in the sample embodiment when the strain is 0-5% is less than 3 MPa, and the maximum value of the stress when the strain is 0-20% is less than 15 MPa.

[0199] In the stress-strain curve of Comparative Example 1-1 in the tensile test, there is a yield point showing a maximum value in the interval of strain of 0.5 to 10%. In the region of strain of 0 to about 1%, the stress increases linearly and monotonically. At a strain of about 1%, the stress shows a maximum value of about 17MPa, and decreases sharply to about 12MPa. In this way, in Comparative Example 1-1, before and after the strain is about 1%, the stress changes from an increasing tendency to a decreasing tendency. Afterwards, in the region of strain of about 1 to about 13%, the stress monotonically decreases to about 12 to about 10MPa. Afterwards, in the region of strain of about 13 to 20%, the stress monotonically increases to about 10 to about 12MPa. In this way, in the stress-strain curve of Comparative Example 1-1, the maximum value of the stress when the strain is 0 to 5% is greater than 3MPa, and the maximum value of the stress when the strain is 0 to 20% is greater than 15MPa.

[0200] 1.1.7.5. Tensile Test of Sensor Sheet

[0201] Next, the tensile test performed on the sensor sheet will be described. The sensor sheets related to Samples 1-1 to 1-2 and Sample 1-3 are cut into strips of 90 mm × 20 mm to produce test pieces. The thickness of the sensor sheet is different in Samples 1-1 to 1-2 and Sample 1-3, but is approximately 1 mm. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a constituting the first electrode sheet and the second electrode sheet is set to 45°.

[0202] A wire is connected to one end of the first electrode sheet in the length direction and is connected to a DC power supply. A wire is connected to the other end of the first electrode sheet in the length direction and is connected to a voltage measuring device.

[0203] The test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec, and the stress is calculated by dividing the load by the cross-sectional area of the test piece. In addition, during the tensile test, the DC resistance value (an example of the resistance value) of the sensor sheet is calculated based on the voltage of the DC power supply and the voltage drop of the sensor sheet.

[0204] Fig.12 The stress-strain curve in the tensile test performed on the sensor sheet is shown. Fig.12 A graph showing the region where the strain is 0 to 20% is shown. The stress of Samples 1-1 to 1-2 monotonically increases in the region where the strain is 0 to 20%. In the stress-strain curves of Samples 1-1 and 1-2 during the tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%.

[0205] Sample 1-1 shows a stress of approximately 0.5 MPa at a strain of 5% and shows a maximum stress of approximately 2.6 MPa at a strain of 20%. Sample 1-2 shows a stress of approximately 0.3 MPa at a strain of 5% and shows a maximum stress of approximately 1.5 MPa at a strain of 20%. In the stress-strain curves of Samples 1-1 and 1-2, the maximum stress at a strain of 0 to 5% is 0.5 MPa or less, and the maximum stress at a strain of 0 to 20% is 3 MPa or less.

[0206] In the stress-strain curves of Samples 1-1 and 1-2, the stress at a strain of 0 to 5% is 0.5 MPa or less, and the maximum stress at a strain of 0 to 20% is 3 MPa or less.

[0207] In the stress-strain curves of Samples 1-3 in the tensile test, there is a yield point showing a maximum value in the strain range of 0.5 to 10%. In the region where the strain is 0 to approximately 3%, the stress linearly and monotonically increases. When the strain is approximately 3%, the stress shows a maximum value of approximately 0.7 MPa and sharply decreases to approximately 0.6 MPa. Thus, in Samples 1-3, before and after the strain of approximately 3%, the tendency of the stress changes from increasing to decreasing. After that, in the region where the strain is approximately 1 to approximately 13%, the stress slightly decreases. Then, in the region where the strain is approximately 13 to 20%, the stress monotonically increases to approximately 0.6 to approximately 0.8 MPa. Thus, in Samples 1-3 in the stress-strain curve, the maximum value of the stress when the strain is 0 to 5% is greater than 0.5 MPa, and the maximum value of the stress when the strain is 0 to 20% is greater than 0.7 MPa.

[0208] When a tensile force is applied to Sample 1-1 and Sample 1-2, the first opening 34a of the first electrode sheet elongates in the tensile direction and contracts in the direction crossing the tensile direction. Fig.13 Taking Sample 1-2 as an example, the deformed state of the first opening 34a is shown. As Fig.13 shown in (a) of [reference], the first opening 34a is open in the state where the elongation rate is 0%. However, as the elongation rate increases to 10% (refer to Fig.13 (b) of [reference]), 20% (refer to Fig.13 (c) of [reference]), 30% (refer to Fig.13 (d) of [reference]), the gap between the fibers of the conductive cloth decreases, and in the state where the elongation rate is 30%, the first opening 34a almost disappears. It is considered that due to such a change in the fiber shape, it can be easily elongated, so the stress generated during elongation is small. That is, it is considered that the existence of the first opening 34a contributes to the structural stretchability and flexibility of the fiber. The above configuration is the same for the second electrode sheet, so the description is omitted. It should be noted that the same applies to Sample 1-1, so the description is omitted.

[0209] It should be noted that the opening ratio of Sample 1-2 is greater than that of Sample 1-1. Therefore, during elongation, as the overall spatial configuration of the filaments 71 changes, the opening area decreases, thereby exerting structural stretchability and flexibility. Therefore, compared with Sample 1-1, the generated stress becomes smaller.

[0210] It is considered that the smaller the generated stress, the smaller the elongation strain applied to the filaments 71 themselves. Therefore, compared with Sample 1-1, it is expected that Sample 1-2 can suppress damage to the plating layer 33 formed on the surface of the filaments 71, and even when a tensile force is applied to the sensor sheet 18, the change in the resistance value can be suppressed.

[0211] It is considered that in Sample 1-1 and Sample 1-2, when a tensile force is applied to the sensor sheet, the first opening portion 34a gradually deforms, whereby the tensile force is absorbed. As a result, at the portion where the warp filament aggregate 72a intersects with the weft filament aggregate 72b, the relative positions of the warp filament aggregate 72a and the weft filament aggregate 72b do not change significantly. Therefore, it is considered that the electrical connection state between the warp filament aggregate 72a and the weft filament aggregate 72b can be maintained. As a result, in Sample 1-1 and Sample 1-2, even when a tensile force is applied to the sensor sheet, the DC resistance value hardly changes.

[0212] In addition, Sample 1-1 and Sample 1-2 do not have a yield point showing a maximum value in the strain range of 0.5 to 5%. It is considered that this is because in the strain range of 0.5 to 5% for Sample 1-1 and Sample 1-2, the structure of the plating layer 33 formed on the first electrode sheet and the second electrode sheet does not change significantly. As a result, the change in the resistance value of the sensor sheet 18 is suppressed.

[0213] On the other hand, Sample 1-3 has a yield point showing a maximum value in the strain range of 0.5 to 5%. In Sample 1-3, it is considered that in the strain range from 0% to the yield point, the plating layer 33 formed at the portion where the warp filament aggregate 72a intersects with the weft filament aggregate 72b is maintained, whereby elastic deformation occurs. It is considered that thereafter, at the yield point, the plating layer 33 formed at the portion where the warp filament aggregate 72a intersects with the weft filament aggregate 72b is damaged.

[0214] Thereafter, in the range where the stress hardly changes (the strain range of about 5 to about 15%), similar to Sample 1-1 and Sample 1-2, it is considered that the tensile force is absorbed by deforming the first opening portion 34a and the second opening portion 34b.

[0215] It is considered that if the strain becomes larger than about 15% thereafter, the first opening ratio and the second opening ratio of Sample 1-3 are 20%. Therefore, the first opening portion 34a and the second opening portion 34b are completely blocked, and the tensile force acting on the first electrode sheet and the second electrode sheet cannot be absorbed. As a result, it is considered that the stress increases.

[0216] 1.1.7.6. Rate of change of DC resistance value of sensor sheet

[0217] Next, for the sensor sheet, the rate of change of the DC resistance value was measured. The sensor sheet was cut into a strip shape of 90 mm × 20 mm to prepare a test piece. The angle formed by the length direction of the test piece and the length direction of the warp filament aggregate 72a was set to 45°.

[0218] A test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec. Wires are connected to both end portions of the first electrode piece, and the DC resistance value between the two wires is measured. Regarding the DC resistance value at this time, based on the following formula (1), the DC resistance value change rate is calculated. The measurement of the DC resistance value uses a digital multimeter 2000 series manufactured by KEITHLEY. The above tests are performed on samples 1-1 to 1-2 and sample 1-3.

[0219] [Equation 1]

[0220]

[0221] Fig.13 It is a graph showing the change of the DC resistance value change rate with respect to strain. The DC resistance value change rate of sample 1-1 increases in the range where the strain is 0 to about 2%, and in the state where the strain is about 2%, the DC resistivity change rate is about 5%. After that, it decreases in the range of about 2 to about 5%, and the DC resistivity change rate becomes about 0%. After that, when the strain is 25% or more, the DC resistance value change rate slowly increases, and the DC resistance value change rate becomes about 7% when the strain is 30%. Thus, the DC resistance value change rate of sample 1-1 is 10% or less in the range where the strain is 0 to 30%.

[0222] The DC resistance value change rate of sample 1-2 increases in the range where the strain is 0 to about 3%, and in the state where the strain is about 3%, the DC resistivity change rate is about 10%. After that, it decreases in the range of about 3 to about 5%, and the DC resistivity change rate becomes about 0%. After that, even when the strain is 30%, the DC resistance value change rate is about 0%. Thus, the DC resistance value change rate of sample 1-2 is 10% or less in the range where the strain is 0 to 30%.

[0223] The DC resistance value change rate of sample 1-3 is about 2% in the range where the strain is 0 to about 3%. After that, in the range where the strain is about 3 to 30%, the DC resistance value change rate monotonically increases, and when the strain is 30%, the DC resistance value change rate is about 130%. Thus, the DC resistance value change rate of sample 1-3 is greater than 10% in the range where the strain is 0 to 30%, and the resistance change during elongation is extremely large compared to samples 1-1 and 1-2.

[0224] 1.7.7.10% Change Rate of DC Resistance Value of Sensor Chip at 10% Elongation

[0225] Next, for the sensor chip, the rate of change of the DC resistance value at 10% elongation was measured. When measuring the rate of change of the DC resistance value of the above-mentioned sensor chip, the following test was repeated a predetermined number of times: After the sensor chip was elongated by 10% relative to the reference length (50 mm) in the state before the tensile force was applied to the sensor chip, it was restored to the reference length and then elongated by 10% again. The number of repetitions in this test was 1 time, 5 times, and 10 times. Regarding the DC resistance value at this time, based on the above formula (1), the rate of change of the DC resistance value was calculated. The above-mentioned test was performed on Samples 1-1 to 1-2 and Sample 1-3.

[0226] Fig.15 The graph showing the relationship between the number of repetitions of the elongation test and the rate of change of the DC resistance value. The rate of change of the DC resistance value at the first measurement of Sample 1-1 was approximately 0%. After that, as the number of repetitions increased, the rate of change of the DC resistance value increased. It was approximately 36% at 1 repetition, approximately 48% at 5 repetitions, and approximately 57% at 10 repetitions. At 10 repetitions, the rate of change of the DC resistivity of Sample 1-1 was 60% or less.

[0227] The rate of change of the DC resistivity at the first measurement of Sample 1-2 was approximately 14%, which was larger than that of Sample 1-1. However, it was approximately 9% at 1 repetition and approximately 15% at 5 repetitions. Even as the number of repetitions increased, the rate of change of the DC resistance value did not increase much. It was approximately 30% at 10 repetitions. At 10 repetitions, the rate of change of the DC resistance value of Sample 1-2 was 50% or less.

[0228] The rate of change of the DC resistance value at the first measurement of Sample 1-3 was the same as that of Sample 1-1, approximately 0%. However, it was approximately 61% at 1 repetition, approximately 89% at 5 repetitions, and approximately 115% at 10 repetitions. As the number of repetitions increased, the rate of change of the DC resistance value increased compared to Samples 1-1 and 1-2.

[0229] As described above, it can be seen that even when the 10% elongation test was repeated, the change in the DC resistance value of the sensor chips related to Samples 1-1 and 1-2 was small compared to Sample 1-3.

[0230] 1.1.7.8. Rate of Change of DC Resistance Value of Sensor Chip at 20% Elongation

[0231] Next, for Samples 1-1 to 1-2 and Sample 1-3, the rate of change of the DC resistance value when the sensor chip was elongated by 20% was measured.

[0232] Fig.16A graph showing the relationship between the number of repetitions of the elongation test and the rate of change of the DC resistance value. The rate of change of the DC resistance value at the first measurement of Sample 1-1 was approximately 0%. After that, it was approximately 35% at 1 repetition, approximately 91% at 5 repetitions, and the rate of change of the DC resistance value increased as the number of repetitions increased. At 10 repetitions, the rate of change of the DC resistance value was approximately 137%.

[0233] The rate of change of the DC resistivity at the first measurement of Sample 1-2 was approximately 10%, which was larger than that of Sample 1-1. However, it was approximately 27% at 1 repetition and approximately 32% at 5 repetitions. Even as the number of repetitions increased, the rate of change of the DC resistance value did not increase much. At 10 repetitions, the rate of change of the DC resistance value of Sample 1-2 was approximately 55%.

[0234] The rate of change of the DC resistance value at the first measurement of Sample 1-3 was approximately 0%, which was the same as that of Sample 1-1. However, it showed approximately 114% at 1 repetition and exceeded 200% at 5 repetitions.

[0235] As described above, it can be seen that even when the 20% elongation test was repeated, the change in the DC resistance value of the sensor chips related to Sample 1-1 and Sample 1-2 was small compared to Sample 1-3.

[0236] 1.1.7.9 Variant 1 of Embodiment 1-1

[0237] As Fig.17 shown, the cross-sectional shape of the filament 71 related to Variant 1 of Embodiment 1-1 is formed into a hexagon. However, the cross-sectional shape of the filament 71 can also be a triangle, a quadrilateral, a pentagon, or a polygon with seven or more sides. In addition, the cross-sectional shape of the filament 71 may not be a regular polygon. In addition, the cross-sectional shapes of the plurality of filaments 71 may not be of one type. For example, it may be configured such that a part is formed into a quadrilateral and other parts are formed into a pentagon.

[0238] 1.1.7.10 Variant 2 of Embodiment 1-1

[0239] As Fig.18 shown, the cross-sectional shape of the filament 71 related to Variant 2 of Embodiment 1-1 can be non-circular, for example, it can also be an oval. In addition, the cross-sectional shape of the filament 71 can be selected as any shape such as a track shape, a strange shape with different maximum diameters of the inscribed circles, etc.

[0240] In addition, the cross-sectional shapes of the plurality of filaments 71 may not be of one type. For example, it may be configured such that a part is formed into a polygon and another part is formed into an oval.

[0241] 1.1.8. Effects of this Embodiment

[0242] Next, the effects of this embodiment will be described. The sensor sheet 18 according to this embodiment includes an insulating sheet 24, a first electrode sheet 25, a first joint portion 36, a second electrode sheet 26, and a second joint portion 37. The insulating sheet 24 has a first surface 27 and a second surface 28 and is formed of a foam. The first electrode sheet 25 is conductive and is disposed on the first surface 27 side of the insulating sheet 24 and has a first opening 34a that penetrates therethrough. The first joint portion 36 joins the insulating sheet 24 and the first electrode sheet 25. The second electrode sheet 26 is conductive and is disposed on the second surface 28 side of the insulating sheet 24 and has a second opening 34b that penetrates therethrough. The second joint portion 37 joins the insulating sheet 24 and the second electrode sheet 26. The first electrode sheet 25 and the second electrode sheet 26 are conductive fabrics woven from a plurality of filament aggregates 72. The plurality of filament aggregates 72 include a plurality of filaments 71 and a plating layer 33 formed on at least a part of the surface of the filaments 71. The first electrode sheet 25 has a first opening 34a that opens between the plurality of filament aggregates 72. The second electrode sheet 26 has a second opening 34b that opens between the plurality of filament aggregates 72. The sensor sheet 18 is configured such that in the stress-strain curve in a tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%. The ratio of the opening area of the first opening 34a to the area of the first electrode sheet 25, i.e., the opening ratio, is 1% or more and 50% or less. The ratio of the opening area of the second opening 34b to the area of the second electrode sheet 26, i.e., the opening ratio, is 1% or more and 50% or less.

[0243] According to this embodiment, when a tensile force is applied to the sensor sheet, the first opening 34a of the first electrode sheet 25 deforms in such a manner that the opening area of the first opening 34a decreases. Then, new conduction paths are formed between the plurality of filament aggregates separated by the first opening. Thus, even when a tensile force is applied to the sensor sheet 18, a change in the resistance value can be suppressed. The same applies to the second opening 34b of the second electrode sheet 26.

[0244] The opening ratio of the first opening 34a is preferably 1% or more and 50% or less. By setting the opening ratio to 50% or less, when the opening area of the first opening 34a deforms in the direction of decreasing, the plurality of filament aggregates 72 are likely to come into contact with each other. In this way, since the plurality of filament aggregates 72 are likely to come into contact with each other, the opening ratio of the first opening 34a is preferably 1% or more and 50% or less, more preferably 1% or more and 40% or less, and further preferably 1% or more and 30% or less. The same applies to the opening ratio of the second opening 34b as that of the first opening 34a.

[0245] In addition, the sensor chip involved in this method is configured such that in the stress-strain curve during a tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%. Thereby, it is possible to suppress the case where the coating layer breaks in the strain range of 0.5 to 10%, and thus it is possible to suppress the change in the resistance value of the sensor chip. In addition, in a region where the strain is small, such as 0.5 to 10%, no large stress is generated, and the rapid change of stress is suppressed. As a result, the efficiency of the operation of assembling the sensor chip 18 to the steering wheel 10 can be improved. Furthermore, by not having a yield point showing a maximum value in the strain range of 0.5 to 5%, when the sensor chip 18 is slightly stretched, no large stress is generated and the stress does not change, so the workability is further improved, and thus it is more preferable.

[0246] When a tensile force is applied to the sensor chip 18, the first opening 34a of the first electrode piece 25 deforms in such a way that the opening area of the first opening 34a decreases. That is, the tensile strain does not concentrate on the fibril 71 itself, and it can elongate by changing the spatial configuration of the whole fibril 71. That is, by the decrease in the opening area accompanying the change in the spatial configuration of the whole fibril 71, the structural stretching flexibility is exerted, so the elongation strain applied to the fibril 71 itself is small, and damage to the coating layer 33 formed on the fibril 71 can be suppressed. Therefore, even when a tensile force is applied to the sensor chip 18, the change in the resistance value can be suppressed.

[0247] The opening ratio of the first opening 34a is preferably 1% or more and 50% or less. By making the opening ratio 50% or less, when deforming in the direction of decreasing the opening area of the first opening 34a, the plurality of fibril aggregates 72 are likely to come into contact with each other. In this way, since the plurality of fibril aggregates 72 are likely to come into contact with each other, the opening ratio of the first opening 34a is preferably 1% or more and 50% or less, more preferably 1% or more and 40% or less, and further preferably 1% or more and 30% or less. Regarding the second opening 34b, it is the same as the first opening 34a.

[0248] The sensor chip 18 involved in this method is configured such that the maximum value of the stress when the strain is 0 to 5% in the stress-strain curve is 0.5 MPa or less. In addition, the sensor chip 18 is configured such that the maximum value of the stress when the strain is 0 to 20% in the stress-strain curve is 3 MPa or less. Thereby, when a tensile force is applied to the sensor chip 18, it is possible to suppress the case where excessive stress is applied to the first electrode piece 25 and the first electrode piece 25a. As a result, it is possible to suppress the case where the structure of the first electrode piece 25 and the first electrode piece 25a is damaged, and thus it is possible to suppress the change in the resistance value of the sensor chip 18.

[0249] From the viewpoint of reducing the stress applied to the first electrode sheets 25 and 25a, or from the viewpoint of reducing the stress applied to the second electrode sheets 26 and 26a, in the stress-strain curve, the maximum value of the stress of the sensor sheet 18 when the strain is 0 to 5% is preferably 0.5 MPa or less, more preferably 0.4 MPa or less, and further preferably 0.3 MPa or less.

[0250] Similarly, from the viewpoint of reducing the stress applied to the first electrode sheets 25 and 25a, or from the viewpoint of reducing the stress applied to the second electrode sheets 26 and 26a, in the stress-strain curve, the maximum value of the stress of the sensor sheet 18 when the strain is 0 to 20% is preferably 3 MPa or less, more preferably 2 MPa or less, and further preferably 1.5 MPa or less.

[0251] In addition, the first electrode sheets 25 and 25a according to the present embodiment are configured such that, in the stress-strain curve, the maximum value of the stress of the first electrode sheets 25 and 25a when the strain is 0 to 5% is 3 MPa or less. In addition, the first electrode sheets 25 and 25a are configured such that, in the stress-strain curve, the maximum value of the stress when the strain is 0 to 20% is 15 MPa or less. It should be noted that the same applies to the second electrode sheets 26 and 26a.

[0252] From the viewpoint of reducing the stress applied to the first electrode sheets 25 and 25a or from the viewpoint of reducing the stress applied to the second electrode sheets 26 and 26a, in the stress-strain curve, the maximum value of the stress of the first electrode sheets 25 and 25a or the second electrode sheets 26 and 26a when the strain is 0 to 5% is preferably 3 MPa or less, more preferably 2 MPa or less, and further preferably 1 MPa or less.

[0253] Similarly, from the viewpoint of reducing the stress applied to the first electrode sheets 25 and 25a or from the viewpoint of reducing the stress applied to the second electrode sheets 26 and 26a, the maximum value of the stress of the first electrode sheets 25 and 25a or the second electrode sheets 26 and 26a when the strain is 0 to 20% is preferably 15 MPa or less, more preferably 10 MPa or less, and further preferably 7 MPa or less.

[0254] The stress-strain curve of the sensor sheet 18 according to the present embodiment is the stress-strain curve in the case where a test piece of 20 mm × 90 mm is held and a tensile test is performed at a tensile speed of 1 mm / s.

[0255] In addition, the cross-sectional shape of the fibrils 71 can be non-circular or polygonal. As a result, an irregular space is formed between the multiple fibrils 71. By moving the fibrils 71 within this space, the tensile force applied to the sensor sheet 18 is absorbed, and thus the situation where excessive stress is applied to the sensor sheet 18 can be suppressed. As a result, the change in the resistance value of the sensor sheet 18 can be suppressed.

[0256] In addition, in the fibril aggregate 72 according to this embodiment, there are also portions that are electrically connected by the coatings 33 formed on the surfaces of adjacent fibrils 71 coming into contact with each other on the outer surfaces of the multiple fibrils 71 located inside the untwisted yarn bundle 74 formed in a bundle shape. Therefore, when a tensile force is applied to the sensor sheet 18, even if the coating 33 formed on the outer surface of the fibril 71 located on the surface of the untwisted yarn bundle 74 breaks, there is still the coating 33 formed on the outer surfaces of the multiple fibrils 71 located inside the untwisted yarn bundle 74. As a result, the coatings 33 formed on the outer surfaces of the multiple fibrils 71 located inside the untwisted yarn bundle 74 come into contact with each other, and thus even when a tensile force is applied to the sensor sheet 18, the change in the resistance value can be suppressed.

[0257] In addition, the fibril aggregate 72 according to this embodiment has an internal space 80 formed in at least a part between adjacent fibrils 71. Inside the internal space 80, the fibrils 71 can move freely. Therefore, when a tensile force is applied to the sensor sheet 18, the fibrils 71 move within the internal space 80, and thus the stress can be absorbed. As a result, the application of excessive stress to the sensor sheet 18 can be suppressed, and thus the situation where the resistance value of the sensor sheet 18 changes can be suppressed.

[0258] In addition, in the fibril aggregate 72 according to this embodiment, a plurality of fibrils 71 are arranged in the plane direction and the normal direction of the sheet surface of the first electrode sheet 25, respectively. The internal space 80 is formed in at least a part between the fibrils 71 adjacent in the plane direction and at least a part between the fibrils 71 adjacent in the normal direction. As a result, the fibrils 71 can move along the plane direction and the normal direction, and thus the stress applied to the sensor sheet 18 by the fibrils 71 can be efficiently absorbed. As a result, the situation where the resistance value of the sensor sheet 18 changes can be suppressed.

[0259] In addition, a coating layer 33 is formed on at least a part of the portion of the surface of the filament 71 that is exposed in the internal space 80. The portion of the surface of the filament 71 that is exposed in the internal space 80 and on which the coating layer 33 is not formed is exposed. Thus, the filament 71 exposed in the internal space 80 can move freely without being restricted by the coating layer 33. As a result, the filament 71 can move within the internal space 80, and thus can efficiently absorb the stress applied by the filament 71 to the sensor chip 18. As a result, a change in the resistance value of the sensor chip 18 can be suppressed.

[0260] In addition, a coating layer 33 is formed on at least a part of the non-exposed portion 81 where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other. As a result, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected, and thus a conduction path of the sensor chip 18 can be formed.

[0261] In addition, a coating layer 33 is formed on at least a part of the surface of the filament 71 that is exposed on the outer surface of the filament aggregate 72. The portion of the surface of the filament 71 that is exposed on the outer surface of the filament aggregate 72 and on which the coating layer 33 is not formed is exposed. Since a coating layer 33 is formed on at least a part of the surface of the filament 71 that is exposed on the outer surface of the filament aggregate 72, the filaments 71 are electrically connected to each other by bringing the coating layer 33 formed on the surface of one filament 71 into contact with the coating layer 33 formed on the surface of another filament 71. In addition, the portion of the surface of the filament 71 on which the coating is not formed allows the filament 71 to move relatively freely, and thus can absorb the tensile force applied to the sensor chip 18. As a result, a situation where excessive stress is applied to the sensor chip 18 can be suppressed, and thus a change in the resistance value of the sensor chip 18 can be suppressed.

[0262] The plurality of filament aggregates 72 according to this embodiment include a warp filament aggregate 72a and a weft filament aggregate 72b. At the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other, a coating layer 33 is formed on at least a part of the portion where the filament 71 exposed on the outer surface of the warp filament aggregate 72a faces the filament 71 exposed on the outer surface of the weft filament aggregate 72b. The outer surface of the filament 71 is exposed at the portion where the coating layer 33 is not formed.

[0263] The coating layer 33 according to this embodiment is a single layer made of nickel, or a multi-layer including a layer made of copper and a layer made of nickel.

[0264] In addition, the manufacturing method of the sensor chip 18 according to this embodiment includes:

[0265] a step of forming a filament aggregate 72 by gathering a plurality of filaments 71;

[0266] A process of forming a base fabric by weaving a plurality of fibril aggregates 72;

[0267] A process of forming an electrically conductive fabric by plating the base fabric; and

[0268] A process of forming the sensor sheet 18 by bonding the electrically conductive fabric to the first surface 27 of the insulating sheet 24 made of an elastic body having the first surface 27 and the second surface 28.

[0269] According to the above manufacturing method of the sensor sheet 18, there are cases where the plating layers 33 formed on the surfaces of adjacent fibrils 71 are electrically connected to each other by coming into contact with each other, and cases where the plating layers 33 are not formed on the surfaces of adjacent fibrils 71 and they can move freely relative to each other. Thus, when a tensile force is applied to the sensor sheet 18, the fibrils 71 that can move freely relative to each other absorb the stress, thereby suppressing the situation where an excessive stress is applied to the sensor sheet 18. As a result, the electrical connection of the sensor sheet 18 is maintained by the electrically connected fibrils 71 to each other, so that a change in the resistance value of the sensor sheet 18 can be suppressed.

[0270] (Embodiment 2-1)

[0271] Next, Embodiment 2-1 will be described. Embodiment 2-1 has the same configuration as that described in 1.1.1 to 1.1.5 of Embodiment 1-1. Therefore, the descriptions of 1.1.1 to 1.1.5 are replaced with 2.1.1 to 2.1.5, and the repeated descriptions are omitted.

[0272] 2.1.6. Configuration of the electrode sheets

[0273] Refer to Fig.19 and Fig.21 , and the first electrode sheet 25, the first electrode sheet 25a, the second electrode sheet 26, and the second electrode sheet 26a will be described. The first electrode sheet 25, the first electrode sheet 25a, the second electrode sheet 26, and the second electrode sheet 26a are electrically conductive fabrics having conductivity. The first electrode sheet 25, the first electrode sheet 25a, the second electrode sheet 26, and the second electrode sheet 26a have conductivity and flexibility. The first electrode sheet 25, the first electrode sheet 25a, the second electrode sheet 26, and the second electrode sheet 26a have stretchability in the length direction X and the cross direction Y.

[0274] As Fig.19 shown, the first electrode sheet 25 and the second electrode sheet 26 are manufactured by forming the plating layer 33 on a base fabric woven from a plurality of fibrils 71. In addition, as Fig.21As shown, the first electrode sheet 25a and the second electrode sheet 26a are manufactured by forming a plating layer 33 on a base fabric formed by weaving a plurality of twisted yarns 73. Each twisted yarn 73 is formed by twisting a plurality of filaments 71.

[0275] Examples of the resin constituting the filaments 71 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyamides such as nylon 6 and nylon 66. However, the resin constituting the warp yarns 41 and the weft yarns 42 is not limited to the above, and any resin can be appropriately selected. The second electrode sheet 26 also has the same configuration.

[0276] The method of forming the plating layer 33 is not particularly limited. For example, it can be electroplating, electroless plating, or electroless plating can be performed after electroplating, or electroplating can be performed after electroless plating. Any method can be appropriately selected.

[0277] As the metal constituting the plating layer 33 formed on the surface of the base fabric, any metal or alloy such as copper, nickel, tin, and solder can be appropriately selected. The plating layer 33 formed on the surface of the base fabric can be composed of one metal or multiple metals. For example, only copper can be plated on the surface of the base fabric, only nickel can be plated on the surface of the base fabric, or a copper plating layer composed of copper can be formed on the surface of the base fabric, and a nickel plating layer composed of nickel can be formed on the surface of the copper plating layer. The plating layer 33 formed on the surface of the base fabric can be formed by electroplating or electroless plating. The second electrode sheet 26 also has the same configuration.

[0278] 2.1.7. Examples, Comparative Examples, and Samples

[0279] 2.1.7.1. Example 2-1 and Sample 2-1

[0280] (Example 2-1 and Sample 2-1)

[0281] Refer to Figure 19-20 , and Example 2-1 will be described. As shown in (a) of Fig.19 , the first electrode sheet 25 of this Example 2-1 includes a plurality of warp yarns 41 and a plurality of weft yarns 42. The first electrode sheet 25 is formed by weaving the warp yarns 41 and the plurality of weft yarns 42. The warp yarn 41 is composed of a single filament 71 and a plating layer 33 formed on the surface of the filament 71, and the weft yarn 42 is composed of a single filament 71 and a plating layer 33 formed on the surface of the filament 71. Since the first electrode sheet 25 and the second electrode sheet 26 have substantially the same configuration, in the following description, repeated explanations will be omitted unless otherwise specified.

[0282] The first electrode sheet 25 has a first opening 34a that opens between two adjacent ones of the plurality of warp threads 41 and two adjacent ones of the plurality of weft threads 42. The first opening 34a penetrates the first electrode sheet 25. In the present Example 2-1, the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25 to the area of the first electrode sheet 25, that is, the opening ratio, is approximately 63%. It should be noted that this opening ratio is the ratio of the total opening area of the plurality of first openings 34a in the target area formed in the first electrode sheet 25 to the area of the target area of the first electrode sheet 25. This opening ratio is calculated, for example, by determining a target area of 10 mm × 10 mm in the first electrode sheet 25, summing up the areas of the first openings 34a within the target area, and dividing the total area by the area of the target area.

[0283] As Fig.19 shown in (b) of, the second electrode sheet 26 of the present Example 2-1 has a plurality of warp threads 41 and a plurality of weft threads 42. The second electrode sheet 26 is formed by weaving the warp threads 41 and the plurality of weft threads 42. Each of the warp threads 41 is composed of a single filament 71, and each of the weft threads 42 is composed of a single filament 71.

[0284] The second electrode sheet 26 has a second opening 34b that opens between two adjacent ones of the plurality of warp threads 41 and two adjacent ones of the plurality of weft threads 42. In the present Example 2-1, the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26 to the area of the second electrode sheet 26, that is, the opening ratio, is approximately 63%.

[0285] As Fig.19 shown in (a) of, the longitudinal direction S of the plurality of warp threads 41 is arranged to cross the longitudinal direction X of the first electrode sheet 25. In addition, the longitudinal direction T of the plurality of weft threads 42 is arranged to cross the longitudinal direction X of the first electrode sheet 25. Specifically, the acute angle of the longitudinal direction S of the plurality of warp threads 41 with respect to the longitudinal direction X of the first electrode sheet 25 is substantially 45°. In addition, the acute angle of the longitudinal direction T of the plurality of weft threads 42 with respect to the longitudinal direction X of the first electrode sheet 25 is substantially 45°. The angle being substantially 45° includes the case of being 45°, and also includes the case where it can be recognized as being substantially 45°.

[0286] When the longitudinal direction S of the warp thread 41 is parallel to the longitudinal direction X of the first electrode sheet 25 (when the acute angle is substantially 0°), if the first electrode sheet 25 is stretched parallel to the direction X, the warp thread 41 itself will be stretched, and a large load is required.

[0287] On the other hand, when the length direction S of the warp 41 is inclined at an angle of 45° obliquely with respect to the length direction X of the first electrode sheet 25 (when the acute angle is substantially 45°), when the first electrode sheet 25 is stretched in parallel with the length direction X, the square or rectangular grid formed by the weft 42 and the warp 41 is deformed into a rhombus shape, and the warp 41 or the weft 42 itself is not stretched, so no large load is required. That is, when the acute angle is substantially 45°, structural flexibility is imparted. In addition, the higher the aperture ratio, the easier it is for the square or rectangular grid to be deformed into a rhombus shape, and the structural flexibility is not easily impaired.

[0288] However, it is also possible that the acute angle of the length direction S of the plurality of warps 41 with respect to the length direction X of the first electrode sheet 25 is an angle different from 45°. In addition, it is also possible that the acute angle of the length direction T of the plurality of wefts 42 with respect to the length direction X of the first electrode sheet 25 is an angle different from 45°. Regarding the second electrode sheet 26, since it is the same as the first electrode sheet 25, repeated description is omitted.

[0289] As Fig.19 shown in (a) of [], the intervals between the plurality of warps 41 according to this embodiment are arranged to be substantially equidistant. However, substantially equidistant includes the case of equidistant, and also includes the case where it can be recognized as substantially equidistant even if it is not equidistant. It should be noted that the intervals between the plurality of warps 41 may also be different from each other.

[0290] In addition, the intervals between the plurality of wefts 42 according to this embodiment are arranged to be substantially equidistant. However, substantially equidistant includes the case of equidistant, and also includes the case where it can be recognized as substantially equidistant even if it is not equidistant. It should be noted that the intervals between the plurality of wefts 42 may also be different from each other.

[0291] As Fig.19 shown in (b) of [], the structure of the second electrode sheet 26 is the same as that of the first electrode sheet 25, so repeated description is omitted.

[0292] As Fig. 20 shown, a coating layer 33 is formed on at least a part of the warp 41. The coating layer 33 may be formed on the entire surface of the warp 41, or may be formed on a part of the surface of the warp 41.

[0293] In addition, a coating layer 33 is formed on at least a part of the weft 42. The coating layer 33 may be formed on the entire surface of the weft 42, or may be formed on a part of the surface of the weft 42.

[0294] In this embodiment, the warp 41 and the weft 42 are electrically connected by bringing the plating layer 33 formed on the surface of the warp 41 into contact with the plating layer 33 formed on the surface of the weft 42.

[0295] In the present Example 2-1, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is 60 to 65 μm. The metal constituting the plating layer 33 is formed in a three-layer structure, with Ni as the outermost layer, Cu as the intermediate layer, and Ni as the innermost layer (on the side of the filament 71).

[0296] As Figure 4 shown, the above-described first electrode piece 25 is joined to the first surface 27 of the insulating piece 24 formed mainly of a foamed resin via the first joining portion 36. The insulating piece 24 is an ether-based polyurethane foam. The thickness of the insulating piece is approximately 1.0 mm. The first joining portion 36 is an acrylic adhesive manufactured by NOGAWA CHEMICAL Co., Ltd. The thickness of the first joining portion 36 is 50 μm. In addition, a second electrode piece 26 having the same configuration as the first electrode piece 25 is joined to the second surface 28 of the insulating piece 24 via the second joining portion 37. Since the first joining portion 36 and the second joining portion 37 are the same, repeated description is omitted. In this way, the sample 2-1 of the sensor piece 18 related to the first electrode piece 25 and the second electrode piece 26 of Example 2-1 is manufactured.

[0297] 2.1.7.2. Example 2-2 and Sample 2-2

[0298] (Example 2-2 and Sample 2-2)

[0299] Next, referring to Fig.21 in (a) to Fig.21 (b), the configuration of the first electrode piece 25a and the second electrode piece 26a related to Example 2-2 will be described. The first electrode piece 25a related to this method is a conductive cloth formed by weaving a plurality of filament aggregates 72. The plurality of filament aggregates 72 include a twisted yarn 73 formed by twisting a plurality of filaments 71 and a plating layer 33 formed on at least a part of the surface of the twisted yarn 73. In addition, the plurality of filament aggregates 72 include a warp filament aggregate 72a and a weft filament aggregate 72b. In the following description, when the warp filament aggregate 72a and the weft filament aggregate 72b are not distinguished and described, they are sometimes referred to as the filament aggregate 72. It should be noted that in the reference numerals used later, as long as the reference numerals identical to those used in the already presented embodiments are not particularly shown, they represent the same constituent elements as those in the already presented embodiments.

[0300] The first electrode sheet 25a involved in this method is formed as follows: a base fabric is formed by weaving a warp thread 73 formed by twisting a plurality of filaments 71 and a weft thread 73 formed by twisting a plurality of filaments 71, and a coating layer 33 is formed on the surface of the base fabric. However, the manufacturing method of the first electrode sheet 25a is not limited to the above method. Since the first electrode sheet 25a and the second electrode sheet 26a have substantially the same configuration, in the following description, repeated descriptions are omitted unless otherwise specified.

[0301] As Fig.21 shown in (a) of [], the first electrode sheet 25a of this method includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The first electrode sheet 25a has a first opening 34a that opens between the plurality of filament aggregates 72. The first opening 34a penetrates the first electrode sheet 25a. In the second embodiment 2-2, the opening ratio, which is the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25a to the area of the first electrode sheet 25a, is 63%.

[0302] As Fig.21 shown in (b) of [], the second electrode sheet 26a of this method is substantially the same as the first electrode sheet 25a except that it has a second opening 34b that opens between the plurality of filament aggregates 72, so repeated descriptions are omitted. In the second embodiment 2-2, the opening ratio, which is the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26a to the area of the second electrode sheet 26a of this method, is 63%.

[0303] There is no particular limitation on the number of filaments 71 included in the filament aggregate 72 that constitutes the first electrode sheet 25a. The filament aggregate 72 involved in this method has six filaments 71, but it can also be two to five or seven or more.

[0304] As Fig.21 shown in (a) of [], the longitudinal direction S of the plurality of warp filament aggregates 72a is arranged to cross the longitudinal direction X of the first electrode sheet 25a. In addition, the longitudinal direction T of the plurality of weft filament aggregates 72b is arranged to cross the longitudinal direction X of the first electrode sheet 25a. Specifically, the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode sheet 25a is substantially 45°. In addition, the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode sheet 25a is substantially 45°. The angle being substantially 45° includes the case of being 45°, and also includes the case where it can be recognized as being substantially 45°.

[0305] However, it is also possible that the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode sheet 25a is an angle different from 45°. Additionally, it is also possible that the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode sheet 25a is an angle different from 45°.

[0306] As Fig.21 shown in (a) of , the intervals between the plurality of warp filament aggregates 72a according to this embodiment are arranged to be substantially equidistant. However, substantially equidistant includes the case of equidistant, and also includes the case where it can be recognized as substantially equidistant even if it is not equidistant. Additionally, the intervals between the plurality of weft filament aggregates 72b are also arranged to be substantially equidistant.

[0307] In this embodiment, the intervals between the plurality of warp filament aggregates 72a and the intervals between the plurality of weft filament aggregates 72b are set to be substantially the same. However, the intervals between the plurality of warp filament aggregates 72a and the intervals between the plurality of weft filament aggregates 72b can also be different.

[0308] As Fig. 22 shown, a coating layer 33 is formed on at least a part of the surface of the twisted yarn 73 constituting the filament aggregate 72. In this embodiment, the coating layer 33 is formed on the surface of the filaments 71 exposed to the outside in the surface of the twisted yarn 73.

[0309] By bringing the coating layer 33 of the warp filament aggregate 72a into contact with the coating layer 33 of the weft filament aggregate 72b, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected.

[0310] Additionally, in this embodiment, a coating layer 33 is not formed on a part of the surface of the filaments 71 exposed inside the twisted yarn 73 in the surface of the filaments 71 constituting the twisted yarn 73. Thus, the surface of the filaments 71 exposed inside the twisted yarn 73 is formed in a state of being exposed in the space inside the twisted yarn 73. On the other hand, in this embodiment, a coating layer 33 is formed on another part of the surface of the filaments 71 exposed inside the twisted yarn 73 in the surface of the filaments 71 constituting the twisted yarn 73. In this way, in this embodiment, the surface of the filaments 71 exposed inside the twisted yarn 73 has a part where the surface of the filaments 71 is exposed and a part where the coating layer 33 is formed.

[0311] The part where the coating layer 33 is not formed and the surface of the filaments 71 is exposed is configured to be more easily movable than the part where the coating layer 33 is formed. Thus, when stress is applied to the sensor sheet, the filaments 71 that can move relatively freely can be used to absorb the stress.

[0312] In this Example 2-2, the resin constituting the fibril 71 is PET (polyethylene terephthalate), and the diameter of the fibril 71 is about 20 μm. The outermost layer of the metal constituting the coating layer 33 is Ni, and the innermost layer (on the side of the fibril 71) is formed of Cu. The twisted yarn 73 is composed of six fibrils 71.

[0313] Similar to Sample 2-1, a sample 2-2 of the sensor sheet 18 related to the first electrode sheet 25a and the second electrode sheet 26a of Example 2-2 was fabricated. Descriptions repeated from Sample 2-1 are omitted.

[0314] (Modification 1 of Example 2-2)

[0315] Next, with reference to Fig.23 , Modification 1 of Example 2-2 will be described. As shown in Fig.23 , a coating layer 33 is formed on at least a part of the surface of the fibril 71. In this Modification 1, the coating layer 33 is formed on the surface of each fibril 71 except at the contact points where adjacent fibrils 71 contact each other. In this Modification 1, the coating layer 33 is also formed on the surface of the fibril 71 located inside the twisted yarn 73 among the surfaces of the fibrils 71.

[0316] (Modification 2 of Example 2-2)

[0317] Next, with reference to Fig.24 , Modification 2 of Example 2-2 will be described. As shown in Fig.24 , the coating layer 33 is formed over the entire circumference of the surfaces of the plurality of fibrils 71 constituting the twisted yarn 73. By bringing the coating layers 33 formed on the surfaces of adjacent fibrils 71 into contact, adjacent fibrils 71 are electrically connected to each other.

[0318] 2.1.7.3. Comparative Example 2-1 and Sample 2-3

[0319] (Comparative Example 2-1 and Sample 2-3)

[0320] Next, with reference to Figure 25-26 , Comparative Example 2-1 will be described. As shown in Fig.25 , the first electrode sheet 25b related to Comparative Example 2-1 is a conductive cloth woven from a plurality of fibril aggregates 72. The plurality of fibril aggregates 72 include an untwisted yarn bundle 74 in which a plurality of fibrils 71 are gathered in an untwisted state and a coating layer 33 formed on at least a part of the surface of the untwisted yarn bundle 74. The fibril aggregate 72 is formed in a flat shape in the thickness direction of the first electrode sheet 25b.

[0321] The first electrode sheet 25b involved in Comparative Example 2-1 is formed as follows: A base fabric is formed by weaving a warp 41 formed by gathering a plurality of filaments 71 in an untwisted state and a weft 42 formed by gathering a plurality of filaments 71 in an untwisted state, and a plating layer 33 is formed on the surface of the base fabric. However, the manufacturing method of the first electrode sheet 25b is not limited to the above method. Since the first electrode sheet 25b has substantially the same configuration as the second electrode sheet 26b, in the following description, repeated descriptions are omitted unless otherwise specified.

[0322] As Fig.25 shown in (a) of [], the first electrode sheet 25b of this embodiment includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The first electrode sheet 25b has a first opening 34a that opens between the plurality of filament aggregates 72. The first opening 34a penetrates the first electrode sheet 25b. The opening ratio, which is the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25b in Comparative Example 2-1 to the area of the first electrode sheet 25b, is approximately 20%.

[0323] As Fig.25 shown in (b) of [], the second electrode sheet 26b of this embodiment is substantially the same as the first electrode sheet 25b except that it has a second opening 34b that opens between the plurality of filament aggregates 72, so repeated descriptions are omitted. The opening ratio, which is the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26b to the area of the second electrode sheet 26 of this embodiment, is approximately 20%.

[0324] There is no particular limitation on the number of filaments 71 included in the filament aggregate 72 constituting the first electrode sheet 25b. The filament aggregate 72 involved in this embodiment includes six filaments 71, but it may also be two to five or seven or more. The plurality of filaments 71 included in the filament aggregate 72 are arranged in a single layer.

[0325] As Fig.26 shown, a plating layer 33 is formed on at least a part of the surface of the untwisted yarn bundle 74 constituting the filament aggregate 72. In this embodiment, the plating layer 33 is formed over the entire circumference of the surface of the untwisted yarn bundle 74.

[0326] The warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected by bringing the plating layer 33 of the warp filament aggregate 72a into contact with the plating layer 33 of the weft filament aggregate 72b.

[0327] As Fig.25As shown in (a) of [reference], the longitudinal direction S of the plurality of warp filament aggregates 72a is arranged to cross the longitudinal direction X of the first electrode plate 25a. Further, the longitudinal direction T of the plurality of weft filament aggregates 72b is arranged to cross the longitudinal direction X of the first electrode plate 25a. Specifically, the acute angle formed by the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode plate 25a is substantially 45°. Further, the acute angle formed by the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode plate 25a is substantially 45°. The angle being substantially 45° includes the case of being 45°, and also includes the case where it can be recognized as being substantially 45°.

[0328] However, it may also be that the acute angle formed by the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode plate 25a is an angle different from 45°. Further, it may also be that the acute angle formed by the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode plate 25a is an angle different from 45°.

[0329] In this sample 2-3, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is 10 to 20 μm. The metal constituting the coating layer 33 has a three-layer structure, with the outermost layer being Ni, the intermediate layer being Cu, and the innermost layer (on the side of the filament 71) being Ni. The untwisted yarn bundle 74 is composed of six filaments 71.

[0330] Similar to Sample 2-1, a sample 2-3 of the sensor sheet 18 related to the first electrode plate 25b and the second electrode plate 26b of Comparative Example 2-1 was produced. Descriptions repeated with Sample 2-1 are omitted.

[0331] 2.1.7.4. Tensile Test of the First Electrode Plate

[0332] Next, with reference to Fig. 27 , a description will be given of the tensile test performed on the first electrode plate. The first electrode plates related to Examples 2-1 to 2-2 and Comparative Example 2-1 were cut into strips of 150 mm × 20 mm to produce test pieces. The thickness of the first electrode plate is approximately 0.1 mm. The angle formed by the longitudinal direction of the test piece with the longitudinal direction of the warp 41 or the warp filament aggregate 72a was set to 45°.

[0333] The test piece was held by a pair of chucks. The distance between the pair of chucks was 70 mm. A tensile test was performed on the test piece at a tensile speed of 1 mm / sec, and the stress was calculated by dividing the load by the cross-sectional area of the test piece. The tensile testing machine was AGS-X 1 kN manufactured by Shimadzu Corporation. The tensile test was performed in the range where the strain was 0 to 20%. Fig. 27 is a graph showing the change of stress with respect to strain.

[0334] In the region of strain of 0 to 20%, the stress of Examples 2-1 and 2-2 increases monotonically very slowly. In the stress-strain curves of Examples 2-1 and 2-2 in the tensile test, there is no yield point showing a maximum value in the region of strain of 0.5 to 10%.

[0335] Example 2-1 shows a stress of about 0.4 MPa when the strain is 5%, and shows a maximum stress of about 0.8 MPa when the strain is 20%. Therefore, the maximum value of the stress of Example 2-1 in the tensile test is less than 1 MPa. Similarly, Example 2-2 shows a stress of about 0.3 MPa when the strain is 5%, and shows a maximum stress of about 0.5 MPa when the strain is 20%. Therefore, for Example 2-2, the maximum value of the stress in the tensile test is also less than 1 MPa. In the stress-strain curves of Example 2-1 and Example 2-2, the maximum value of the stress when the strain is 0 to 5% is less than 3 MPa, and the maximum value of the stress when the strain is 0 to 20% is less than 15 MPa.

[0336] In the stress-strain curve of Comparative Example 2-1 in the tensile test, there is a yield point showing a maximum value in the interval of strain of 0.5 to 10%. In the region of strain of 0 to about 1%, the stress increases linearly and monotonically. At a strain of about 1%, the stress shows a maximum value of about 17MPa, which decreases sharply to about 12MPa. In this way, in Comparative Example 2-1, before and after the strain is about 1%, the stress changes from an increasing tendency to a decreasing tendency. Afterwards, in the region of strain of about 1 to about 13%, the stress monotonically decreases to about 12 to about 10MPa. Afterwards, in the region of strain of about 13 to 20%, the stress monotonically increases to about 10 to about 12MPa. In this way, in the stress-strain curve of Comparative Example 2-1, the maximum value of the stress when the strain is 0 to 5% is greater than 3MPa, and the maximum value of the stress when the strain is 0 to 20% is greater than 15MPa.

[0337] 2.1.7.5. Tensile test of sensor sheet

[0338] Next, the tensile test performed on the sensor sheet is described. The sensor sheets involved in samples 2-1 to 2-2 and sample 2-3 are cut into strips of 90 mm × 20 mm to prepare test sheets. The thickness of the sensor sheet is about 1 mm. The angle formed by the length direction of the test sheet and the length direction of the warp 41 or the warp filament assembly 72a constituting the first electrode sheet and the second electrode sheet is set to 45°.

[0339] A wire is connected to one end of the first electrode plate in the length direction and is connected to a DC power supply. A wire is connected to the other end of the first electrode plate in the length direction and is connected to a voltage measuring device.

[0340] A test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec, and the stress is calculated by dividing the load by the cross-sectional area of the test piece. In addition, during the tensile test, the DC resistance value (an example of the resistance value) of the sensor piece is calculated based on the voltage of the DC power supply and the voltage drop of the sensor piece. The measurement of the DC resistance value uses a digital multimeter 2000 series manufactured by KEITHLEY.

[0341] As Fig.28 shown, Sample 2-1 shows a stress of about 0.1 MPa at a strain of 5%, a stress of about 0.4 MPa at a strain of 20%, and a stress of about 1.3 MPa, which is the maximum value of the stress, at a strain of 30%.

[0342] Sample 2-2 shows a stress of about 0.1 MPa at a strain of 5%, a stress of about 0.4 MPa at a strain of 20%, and a stress of about 0.9 MPa, which is the maximum value of the stress, at a strain of 30%.

[0343] In the stress-strain curve of Sample 2-1 and Sample 2-2, the stress is 0.5 MPa or less when the strain is 0 to 5%, and the maximum value of the stress is 3 MPa or less when the strain is 0 to 20%.

[0344] In the stress-strain curve of Sample 2-1 and Sample 2-2, the stress is 0.5 MPa or less when the strain is 0 to 5%, and the maximum value of the stress is 3 MPa or less when the strain is 0 to 20%.

[0345] In the stress-strain curve of Sample 2-3 in the tensile test, there is a yield point showing a maximum value in the strain range of 0.5 to 10%. In the region where the strain is 0 to about 3%, the stress linearly and monotonically increases. When the strain is about 3%, the stress shows a maximum value of about 0.7 MPa and sharply decreases to about 0.6 MPa. Thus, in Sample 2-3, before and after the strain is about 1%, the stress changes from an increasing trend to a decreasing trend. After that, in the region where the strain is about 1 to about 13%, the stress slightly decreases. After that, in the region where the strain is about 13 to 30%, the stress monotonically increases to about 0.6 to about 1.7 MPa. Thus, in the stress-strain curve of Sample 2-3, the maximum value of the stress is greater than 0.5 MPa when the strain is 0 to 5%, and the maximum value of the stress is greater than 0.7 MPa when the strain is 0 to 20%.

[0346] When a tensile force is applied to Sample 2-1 and Sample 2-2, the first opening 34a of the first electrode sheet elongates in the tensile direction and contracts in a direction crossing the tensile direction. Fig.29 Taking Sample 2-1 as an example, it shows the deformed state of the first opening 34a. Thus, the tensile force is absorbed, and it is considered that the change in stress is small. It should be noted that the same applies to Sample 2-2, so the description is omitted.

[0347] In Sample 2-1 and Sample 2-2, even when a tensile force is applied to the sensor sheet, at the intersection of the warp 41 and the weft 42, the relative positions of the warp 41 and the weft 42 do not change significantly. Therefore, it is considered that the electrical connection state between the warp 41 and the weft 42 can be maintained. Thus, in Sample 2-1 and Sample 2-2, even when a tensile force is applied to the sensor sheet, the DC resistance value hardly changes.

[0348] On the other hand, Sample 2-3 has a yield point showing a maximum value in the strain range of 0.5 to 5%. In Sample 2-3, it is considered that in the strain range from 0% to the yield point, the plating layer 33 formed at the intersection of the warp 41 and the weft 42 is maintained, and thus elastic deformation occurs. It is considered that after that, at the yield point, the plating layer 33 formed at the intersection of the warp 41 and the weft 42 is damaged.

[0349] After that, in the range where the stress hardly changes (the strain range of about 5 to about 15%), similar to Sample 2-1 and Sample 2-2, it is considered that the tensile force is absorbed by deforming the first opening 34a and the second opening 34b.

[0350] It is considered that if the strain becomes larger than about 15% later, the first opening ratio and the second opening ratio of Sample 2-3 are 20%. Therefore, the first opening 34a and the second opening 34b are completely blocked, and the tensile force acting on the first electrode sheet and the second electrode sheet cannot be absorbed. Thus, it is considered that the stress increases.

[0351] 2.1.7.6. DC Resistance Value of the Sensor Sheet

[0352] In Fig.30 a graph showing the change of the DC resistance value with respect to the strain is shown. In Fig.30 the DC resistance values in the region where the strain is 0 to 30% are shown.

[0353] In the region where the strain of Sample 2-1 is 0 to 30%, the DC resistance value is about 0.1 Ω and hardly changes. In the region where the strain of Sample 2-2 is 0 to 30%, the DC resistance value is about 0.2 Ω and hardly changes.

[0354] In the region where the strain of Sample 2-3 is 0 to approximately 3%, the DC resistance value is approximately 0.2 Ω and hardly changes. When the strain is greater than approximately 3%, the DC resistance value of Sample 2-3 increases monotonically, and is approximately 0.44 Ω when the strain is 30%. Thus, the DC resistance value of Sample 2-3 varies within the range of approximately 0.2 to approximately 0.44 Ω.

[0355] In the process of assembling the sensor sheet 18 to the steering wheel 10, the sensor sheet 18 is stretched and elongated while being assembled to the steering wheel 10. The sensor sheet 18 is fixed to the steering wheel 10 in a stretched and elongated state. Therefore, the sensor sheet 18 in the state assembled to the steering wheel 10 maintains a state where tension is applied. It is assumed that over time, the residual stress in the material (such as metal, resin, etc.) constituting the sensor sheet 18 relaxes and the tension applied to the sensor sheet 18 changes. If the tension changes, there is a risk that the resistance value of the sensor sheet 18 will change.

[0356] As described above, a tensile force acts on the sensor sheet 18, and this tensile force may change over time. Therefore, when a tensile force is applied to the sensor sheet 18, if the DC resistance value of the sensor sheet 18 changes, the sensitivity of the sensor sheet 18 changes, which is not preferable.

[0357] Sample 2-1 and Sample 2-2 are preferable because the DC resistance value hardly changes in the region where the strain is 0 to 30%.

[0358] On the other hand, Sample 2-3 is not preferable because the DC resistance value varies within the range of approximately 0.2 to approximately 0.44 Ω in the region where the strain is 0 to 30%.

[0359] 2.1.8. Effects of this method

[0360] Next, the effects of this method will be described. The sensor sheet 18 involved in this method includes an insulating sheet 24, a first electrode sheet 25, a first electrode sheet 25a, a first joint portion 36, a second electrode sheet 26, a second electrode sheet 26a, and a second joint portion 37. The insulating sheet 24 has a first surface 27 and a second surface 28 and is formed of a foam. The first electrode sheet 25 and the first electrode sheet 25a are disposed on the first surface 27 side of the insulating sheet 24 and have a first through-opening 34a. The first electrode sheet 25 and the first electrode sheet 25a have conductivity. The first joint portion 36 joins the insulating sheet 24 and the first electrode sheet 25. The second electrode sheet 26 and the second electrode sheet 26a are disposed on the second surface 28 side of the insulating sheet 24 and have a second through-opening 34b. The second electrode sheet 26 and the second electrode sheet 26a have conductivity. The second joint portion 37 joins the insulating sheet 24 and the second electrode sheet 26 and the second electrode sheet 26a. The sensor sheet 18 is configured such that in the stress-strain curve in a tensile test, there is no yield point showing a maximum value in the range where the strain is 0.5 to 10%. The ratio of the opening area of the first opening 34a to the area of the first electrode sheet 25 and the first electrode sheet 25a, that is, the opening ratio, is 40% or more. The ratio of the opening area of the second opening 34b to the area of the second electrode sheet 26 and the second electrode sheet 26a, that is, the opening ratio, is 40% or more.

[0361] Since the ratio of the opening area of the first opening 34a to the area of the first electrode sheet 25 and the first electrode sheet 25a, that is, the opening ratio, is 40% or more, and the ratio of the opening area of the second opening 34b to the area of the second electrode sheet 26 and the second electrode sheet 26a, that is, the opening ratio, is 40% or more, it is possible to absorb the tensile force applied to the sensor sheet 18 by deforming the first opening 34a and the second opening 34b. Thereby, the influence of the tensile force applied to the sensor sheet 18 can be reduced, and thus an increase in the resistance value of the sensor sheet 18 can be suppressed. Since it is easy to absorb the tensile force applied to the sensor sheet 18, the opening ratio is more preferably 50% or more, and further preferably 60% or more.

[0362] The sensor sheet 18 involved in this method is configured such that in the stress-strain curve in a tensile test, there is no yield point showing a maximum value in the range where the strain is 0.5 to 10%. Thus, in a region where the strain is relatively small, such as 0.5 to 10%, no large stress is generated, and a sharp change in stress is suppressed. As a result, the efficiency of the operation of assembling the sensor sheet 18 to the steering wheel 10 can be improved. In addition, by not having a yield point showing a maximum value in the range where the strain is 0.5 to 5%, when the sensor sheet 18 is slightly stretched, no large stress is generated and the stress does not change, so the workability is further improved, and thus it is more preferable.

[0363] In addition, the first electrode sheet 25a and the second electrode sheet 26a involved in this method are conductive cloths formed by weaving a plurality of fibril aggregates 72. The fibril aggregate 72 includes a twisted yarn 73 formed by twisting a plurality of fibrils 71 and a plating layer 33 formed on at least a part of the surface of the twisted yarn 73. The first electrode sheet 25a has a first opening 34a that opens between the plurality of fibril aggregates 72. The second electrode sheet 26a has a second opening 34b that opens between the plurality of fibril aggregates 72.

[0364] By forming the plating layer 33 on at least a part of the surface of the twisted yarn 73 formed by twisting a plurality of fibrils 71, a plurality of conductive paths are formed on the surface of the fibril aggregate 72. Thus, even when a tensile force is applied to the sensor sheet 18 and a part of the plating layer 33 is damaged and a part of the conductive path is broken, the electrical connection can be maintained through other conductive paths. Thereby, a change in the resistance value of the sensor sheet 18 can be suppressed.

[0365] According to this method, in the stress-strain curve in the tensile test, in the range where the strain is 0.5 to 10%, the lattice formed by the warp 41 and the weft 42 is deformed into a rhombus shape. Therefore, not only can it be deformed without a large load, but also the elongation strain of the warp 41 and the weft 42 themselves is suppressed at this time. Therefore, the strain applied to the plating layer 33 formed on the wire is also small, and the damage to the plating layer is suppressed. That is, by arranging the conductive cloth at an angle of 45° with respect to the tensile direction, structural flexibility is exhibited. As a result, the damage to the plating layer 33 formed on the warp 41 or the weft 42 of the conductive cloth during elongation is suppressed, and thus a change in the resistance value of the sensor sheet 18 can be suppressed.

[0366] The sensor sheet 18 involved in this method is configured such that the maximum value of the stress when the strain is 0 to 5% in the stress-strain curve is 0.5 MPa or less. In addition, the sensor sheet 18 is configured such that the maximum value of the stress when the strain is 0 to 20% in the stress-strain curve is 3 MPa or less. Thereby, when a tensile force is applied to the sensor sheet 18, an excessive stress applied to the first electrode sheet 25 and the first electrode sheet 25a can be suppressed. As a result, the structure of the first electrode sheet 25 and the first electrode sheet 25a can be prevented from being damaged, and thus a change in the resistance value of the sensor sheet 18 can be suppressed.

[0367] From the viewpoint of reducing the stress applied to the first electrode sheet 25 and the first electrode sheet 25a, in the stress-strain curve, the maximum value of the stress of the sensor sheet 18 when the strain is 0 to 5% is preferably 0.5 MPa or less, more preferably 0.4 MPa or less, and further preferably 0.3 MPa or less.

[0368] Similarly, from the viewpoint of reducing the stress applied to the first electrode piece 25 and the first electrode piece 25a, in the stress-strain curve, the maximum value of the stress of the sensor piece 18 when the strain is 0 to 20% is preferably 3 MPa or less, more preferably 2 MPa or less, and further preferably 1.5 MPa or less.

[0369] In addition, the first electrode piece 25 and the first electrode piece 25a according to the present embodiment are configured such that in the stress-strain curve, the maximum value of the stress of the first electrode piece 25 and the first electrode piece 25a when the strain is 0 to 5% is 3 MPa or less. In addition, the first electrode piece 25 and the first electrode piece 25a are configured such that in the stress-strain curve, the maximum value of the stress when the strain is 0 to 20% is 15 MPa or less.

[0370] From the viewpoint of reducing the stress applied to the first electrode piece 25 and the first electrode piece 25a, in the stress-strain curve, the maximum value of the stress of the first electrode piece 25 and the first electrode piece 25a when the strain is 0 to 5% is preferably 3 MPa or less, more preferably 2 MPa or less, and further preferably 1 MPa or less.

[0371] Similarly, from the viewpoint of reducing the stress applied to the first electrode piece 25 and the first electrode piece 25a, the maximum value of the stress when the strain is 0 to 20% is preferably 10 MPa or less, more preferably 7 MPa or less, and further preferably 3 MPa or less.

[0372] By configuring the sensor piece 18 or the first electrode piece 25 and the first electrode piece 25a as described above, when a tensile force is applied to the sensor piece 18, it is possible to suppress the situation where an excessive stress is applied to the first electrode piece 25 and the first electrode piece 25a. As a result, it is possible to suppress the situation where the structure of the first electrode piece 25 and the first electrode piece 25a is damaged, and thus it is possible to suppress the change in the resistance value of the sensor piece 18.

[0373] The plating layer 33 according to the present embodiment is formed on at least a part of the surface of the twisted wire 73 and is not formed on at least a part of the inside of the twisted wire 73. As a result, inside the twisted wire 73, there are filaments 71 that are not fixed by the plating layer 33 and can move freely. As a result, even when a tensile force is applied to the sensor piece 18, the stress can be absorbed by the freely movable filaments 71, so that it is possible to suppress the situation where an excessive stress is applied to the first electrode piece 25, the first electrode piece 25a, the second electrode piece 26, and the second electrode piece 26a. As a result, it is possible to suppress the change in the resistance value of the sensor piece 18.

[0374] (Embodiment 3-1)

[0375] Next, Embodiment 3-1 will be described. Embodiment 3-1 has the same configuration as that described in 1.1.1 to 1.1.5 of Embodiment 1-1. Therefore, the descriptions of 1.1.1 to 1.1.5 are replaced with 3.1.1 to 3.1.5, and repeated descriptions are omitted.

[0376] 3.1.6. Configuration of the electrode sheet

[0377] The first electrode sheet 25 and the second electrode sheet 26 are conductive cloths having conductivity. The first electrode sheet 25 and the second electrode sheet 26 have conductivity and flexibility. The first electrode sheet 25 and the second electrode sheet 26 have stretchability in the length direction X and the crossing direction Y.

[0378] As shown in Fig.31 the first electrode sheet 25 and the second electrode sheet 26 are conductive cloths formed by weaving a plurality of filament aggregates 72. The filament aggregate 72 includes a plurality of filaments 71 and a plating layer 33 formed on at least a part of the surface of the filaments 71.

[0379] As shown in Fig.31 (a) to Fig.31 (b) in, the first electrode sheet 25 and the second electrode sheet 26 are manufactured by forming a plating layer 33 on a base cloth formed by weaving a plurality of untwisted yarn bundles 74. Each untwisted yarn bundle 74 is formed by gathering a plurality of filaments 71 in an untwisted state.

[0380] Examples of the resin constituting the filaments 71 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyamides such as nylon 6 and nylon 66. However, the resin constituting the filaments 71 is not limited to the above, and any resin can be appropriately selected. The second electrode sheet 26 also has the same configuration.

[0381] The plating layer 33 is formed on the surface of a base cloth formed by weaving a plurality of filament aggregates 72. The method of forming the plating layer 33 is not particularly limited. For example, it can be electroplating, non-electroplating, electroplating can be performed after non-electroplating, or non-electroplating can be performed after electroplating, and any method can be appropriately selected.

[0382] As the metal constituting the coating layer 33 formed on the surface of the base fabric, any metal or alloy such as copper, nickel, tin, solder, etc. can be appropriately selected. The coating layer 33 formed on the surface of the base fabric may be composed of one metal or may be composed of multiple metals. For example, only copper may be plated on the surface of the base fabric, only nickel may be plated on the surface of the base fabric, or a copper plating layer composed of copper may be formed on the surface of the base fabric, and a nickel plating layer composed of nickel may be formed on the surface of the copper plating layer. The coating layer 33 formed on the surface of the base fabric can be formed by electrolytic plating or can be formed by electroless plating. The second electrode piece 26 also has the same configuration.

[0383] As Fig.31 shown in (a) of [], the first electrode piece 25 has a first opening 34a that opens between a plurality of filament aggregates 72. The first opening 34a penetrates the first electrode piece 25. The ratio of the opening area of the first opening 34a formed in the first electrode piece 25 to the area of the first electrode piece 25, that is, the first opening ratio, is 1% or more and 40% or less.

[0384] As Fig.31 shown in (b) of [], the second electrode piece 26 has a second opening 34b that opens between a plurality of filament aggregates 72. The second opening 34b penetrates the second electrode piece 26. The ratio of the opening area of the second opening 34b formed in the second electrode piece 26 to the area of the second electrode piece 26, that is, the second opening ratio, is 1% or more and 40% or less.

[0385] 3.1.7. Examples, Comparative Examples, and Samples

[0386] 3.1.7.1. Example 3-1 and Sample 3-1

[0387] (Example 3-1 and Sample 3-1)

[0388] Refer to Figure 31 to Figure 34 , and Example 3-1 will be described. As Fig.31 shown in (a) of [], the first electrode piece 25 related to Example 3-1 is a conductive fabric woven from a plurality of filament aggregates 72. The plurality of filament aggregates 72 include an untwisted yarn bundle 74 formed by gathering a plurality of filaments 71 in an untwisted state and a coating layer 33 formed on at least a part of the surface of the untwisted yarn bundle 74. The filament aggregate 72 is formed in a flat shape in the thickness direction of the first electrode piece 25b. However, since the first electrode piece 25 and the second electrode piece 26 have substantially the same configuration, repeated descriptions will be omitted except in special cases.

[0389] The first electrode sheet 25 involved in this Embodiment 3-1 is formed in the following manner: A base fabric is formed by weaving a warp formed by gathering a plurality of filaments 71 in an un-twisted state and a weft formed by gathering a plurality of filaments 71 in an un-twisted state, and a plating layer 33 is formed on the surface of this base fabric. However, the manufacturing method of the first electrode sheet 25 is not limited to the above method.

[0390] As Fig.31 shown in (a) of [], the first electrode sheet 25 of this embodiment includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The first electrode sheet 25 has a first opening 34a that opens between the plurality of filament aggregates 72. The first opening 34a penetrates the first electrode sheet 25. In this Embodiment 3-1, the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25 to the area of the first electrode sheet 25, that is, the opening ratio, is approximately 3%. It should be noted that this opening ratio is the ratio of the total opening area of the plurality of first openings 34a in the target area formed in the first electrode sheet 25 to the area of the target area of the first electrode sheet 25. This opening ratio is calculated, for example, by determining a 10 mm × 10 mm target area in the first electrode sheet 25, summing up the areas of the first openings 34a within the target area, and dividing the total area by the area of the target area.

[0391] As Fig.31 shown in (b) of [], the second electrode sheet 26 of this embodiment includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The second electrode sheet 26 of this embodiment has a second opening 34b that opens between the plurality of filament aggregates 72. The second opening 34b penetrates the second electrode sheet 26. In this Embodiment 3-1, the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26 to the area of the second electrode sheet 26 of this embodiment, that is, the opening ratio, is approximately 3%.

[0392] There is no particular limitation on the number of filaments 71 included in the filament aggregate 72 that constitutes the first electrode sheet 25. The filament aggregate 72 involved in this embodiment includes 75 filaments 71, but it can be set to any number. Additionally, regarding the second electrode sheet 26, it is the same as the first electrode sheet 25.

[0393] As Fig.32 shown, a plating layer 33 is formed on at least a part of the surface of the untwisted yarn bundle 74 that constitutes the filament aggregate 72. By bringing the plating layer 33 of the warp filament aggregate 72a into contact with the plating layer 33 of the weft filament aggregate 72b, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected.

[0394] As Fig.31As shown in (a) therein, the longitudinal direction S of the plurality of warp filament aggregates 72a is arranged to intersect the longitudinal direction X of the first electrode sheet 25. Further, the longitudinal direction T of the plurality of weft filament aggregates 72b is arranged to intersect the longitudinal direction X of the first electrode sheet 25. Specifically, the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode sheet 25 is substantially 45°. Further, the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode sheet 25a is substantially 45°. The angle being substantially 45° includes the case of being 45°, and also includes the case where it can be recognized as being substantially 45°. It should be noted that the second electrode sheet 26 has the same configuration as the first electrode sheet 25, and thus redundant description is omitted.

[0395] When the longitudinal direction S of the warp filament aggregate 72a is parallel to the longitudinal direction X of the first electrode sheet 25 (when the acute angle is substantially 0°), if the first electrode sheet 25 is elongated in parallel with the direction X, the warp filament aggregate 72a itself will be stretched, and a large load is required.

[0396] On the other hand, when the longitudinal direction S of the warp filament aggregate 72a is inclined at an oblique angle of 45° with respect to the longitudinal direction X of the first electrode sheet 25 (when the acute angle is substantially 45°), if the first electrode sheet 25 is elongated in parallel with the direction X, the square or rectangular lattice (opening 34) formed by the warp filament aggregate 72a and the weft filament aggregate 72b is deformed into a rhombus shape, and the warp filament aggregate 72a or the weft filament aggregate 72b itself will not be stretched, so a large load is not required. That is, when the acute angle is substantially 45°, structural flexibility is imparted. Further, the higher the opening ratio, the easier the square or rectangular lattice is deformed into a rhombus shape, and the less likely the structural flexibility is impaired.

[0397] However, it may be that the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode sheet 25 is an angle different from 45°. Further, it may be that the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode sheet 25 is an angle different from 45°.

[0398] The number of filaments 71 that make up the warp filament assembly 72a and the number of filaments 71 that make up the weft filament assembly 72b may be the same or different. In the present Example 3-1, the number of filaments 71 that make up the warp filament assembly 72a and the number of filaments 71 that make up the weft filament assembly 72b are set to be substantially the same. Substantially the same includes the case of being the same, and also includes the case where it can be recognized as substantially the same even when they are not the same. The weft filament assembly 72b is the same as the above, so the repeated description is omitted. In the present Example 3-1, the number of filaments 71 is set to 75. However, the number of filaments 71 is not limited to the above number.

[0399] As Fig.32 shown, a coating layer 33 is formed on at least a part of the plurality of filaments 71 that make up the warp filament assembly 72a. For example, the coating layer 33 is formed on the surface of the filaments 71 that are exposed on the outer surface of the warp filament assembly 72a. The coating layer 33 is not formed on the surface of a part of the filaments 71 located inside the warp filament assembly 72a. At the portion where the coating layer 33 is not formed, the surface of the filament 71 is exposed. The weft filament assembly 72b is the same as the above, so the repeated description is omitted.

[0400] At the portion where the warp filament assembly 72a and the weft filament assembly 72b cross each other facing each other, the coating layer 33 is locally formed, and at the portion where the coating layer 33 is not formed, the surface of the filament 71 is exposed. In the portion where the warp filament assembly 72a and the weft filament assembly 72b cross each other facing each other, the coating layer 33 is formed in the region close to the portion exposed to the outside. On the other hand, in the portion close to the inside, the portion where the coating layer 33 is formed and the portion where the coating layer 33 is not formed coexist. It should be noted that the weft filament assembly 72b also has the same configuration as the warp filament assembly 72a, so the repeated description is omitted.

[0401] Fig.34 The cross-sectional area A1 of each of the warp filament assemblies 72a shown Fig.33The opening area A2 of the first opening portion 34a is large in a state where the first electrode piece 25 shown does not generate strain. The cross-sectional area A1 of the warp filament aggregate 72a refers to the cross-sectional area formed by the outer contour line of the warp filament aggregate 72a. The same applies to the weft filament aggregate 72b. In addition, although not shown in detail, the cross-sectional area A1 of each of the weft filament aggregates 72b is larger than the opening area A2 of the first opening portion 34a in a state where the first electrode piece 25 does not generate strain. In addition, although not shown in detail, in the second electrode piece 26, the cross-sectional area A1 of each of the warp filament aggregates 72a and the cross-sectional area A1 of each of the weft filament aggregates 72b are larger than the opening area A2 of the second opening portion 34b in a state where the second electrode piece 26 does not generate strain.

[0402] From Fig.33 When observing from the thickness direction of the first electrode piece 25 shown, the cross-sectional area A3 of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other is larger than Fig.33 the opening area A2 of the first opening portion 34a shown. In addition, although not shown in detail, when observing from the thickness direction of the second electrode piece 26, the cross-sectional area A3 of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other is larger than the opening area A2 of the second opening portion 34b.

[0403] In the present Embodiment 3-1, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is about 10 μm. The metal constituting the coating layer 33 is formed in a three-layer structure, with Ni on the outermost layer, Cu in the middle layer, and Ni on the innermost layer (on the side of the filament 71). The diameter of the warp filament aggregate 72a is 185 μm, and the diameter of the weft filament aggregate 72b is 185 μm. However, since the second electrode piece 26 has substantially the same configuration as the first electrode piece 25, repeated descriptions are omitted.

[0404] As Figure 4 shown, the above-mentioned first electrode piece 25 is joined to the first surface 27 of the insulating sheet 24 via the first joining portion 36. In addition, a second electrode piece 26 having the same configuration as the first electrode piece 25 is joined to the second surface 28 of the insulating sheet 24 via the second joining portion 37. The insulating sheet 24 is an ether-based polyurethane foam. The first joining portion 36 is an acrylic adhesive manufactured by NOGAWACHEMICAL Co., Ltd. The thickness of the first joining portion 36 is 50 μm. Since the first joining portion 36 is the same as the second joining portion 37, repeated descriptions are omitted. In this way, the sensor sheet 18 related to Sample 3-1 is manufactured.

[0405] 3.1.7.2. Example 3-2 and Sample 3-2

[0406] (Example 3-2 and Sample 3-2)

[0407] Next, referring to Fig.35 (a) to Fig.35 (b) in, the configurations of the first electrode sheet 25a and the second electrode sheet 26a involved in Example 3-2 will be described. In the first electrode sheet 25a involved in this Example 3-2, the number of filaments 71a constituting the warp filament aggregate 72aa is different from the number of filaments 71a constituting the weft filament aggregate 72ba. In this Example 3-2, the number of filaments 71a constituting the warp filament aggregate 72aa is larger than the number of filaments 71a constituting the weft filament aggregate 72ba. However, the number of filaments 71a constituting the warp filament aggregate 72aa may also be smaller than the number of filaments 71a constituting the weft filament aggregate 72ba.

[0408] In this Example 3-2, the number of filaments 71a constituting the warp filament aggregate 72aa is set to be about twice the number of filaments 71 constituting the weft filament aggregate 72ba. In this Example 3-2, the number of filaments 71a constituting the warp filament aggregate 72aa is set to about 80, and the number of filaments 71 constituting the weft filament aggregate 72ba is set to about 40. However, the difference between the number of filaments 71a constituting the warp filament aggregate 72aa and the number of filaments 71a constituting the weft filament aggregate 72ba is not limited to the above.

[0409] In Example 3-2, the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25a to the area of the first electrode sheet 25a, that is, the opening ratio, is about 10%. In addition, the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26a to the area of the second electrode sheet 26a, that is, the opening ratio, is about 10%.

[0410] The second electrode sheet 26a has the same configuration as the first electrode sheet 25a, so redundant descriptions are omitted.

[0411] In this Example 3-2, the resin constituting the filaments 71a is PET (polyethylene terephthalate), and the diameter of the filaments 71a is about 10 μm. The metal constituting the coating layer 33 has a single-layer structure and is a Ni single layer. The diameter of the warp filament aggregate 72aa is about 180 μm, and the diameter of the weft filament aggregate 72ba is about 90 μm.

[0412] The configurations other than the above are the same as those in Example 3-1, so redundant descriptions are omitted.

[0413] In addition, in Example 3-2, the insulating sheet 24 is an ether-based polyurethane foam. The first joint portion 36 is an acrylic-based adhesive. The thickness of the first joint portion 36 is approximately 50 μm. Since the first joint portion 36 is the same as the second joint portion 37, repeated descriptions are omitted. Except for the above, a sample 3-2 of the sensor sheet 18 related to the first electrode sheet 25a and the second electrode sheet 26a of Example 3-2 is produced in the same manner as Sample 3-1. Descriptions repeated with Sample 3-1 are omitted.

[0414] 3.1.7.3. Comparative Example 3-1 and Sample 3-3

[0415] (Comparative Example 3-1 and Sample 3-3)

[0416] Next, with reference to Fig.36 in (a) to Fig.36 in (b), Comparative Example 3-1 will be described. The warp filament aggregate 72ab and the weft filament aggregate 72bb related to Comparative Example 3-1 each have six filaments 71b.

[0417] As shown in Fig.36 in (a), the first electrode sheet 25b of this embodiment includes a plurality of warp filament aggregates 72ab and a plurality of weft filament aggregates 72bb. The first electrode sheet 25b has a first opening 34a that opens between the plurality of warp filament aggregates 72ab and the plurality of weft filament aggregates 72bb. The first opening 34a penetrates the first electrode sheet 25b. The ratio of the opening area of the first opening 34a formed in the first electrode sheet 25b of this Comparative Example 3-1 to the area of the first electrode sheet 25b, that is, the opening ratio, is 20%.

[0418] As shown in Fig.36 in (b), the second electrode sheet 26b of this embodiment is substantially the same as the first electrode sheet 25a except that it has a second opening 34b that opens between the plurality of warp filament aggregates 72ab and the plurality of weft filament aggregates 72bb, so repeated descriptions are omitted. The ratio of the opening area of the second opening 34b formed in the second electrode sheet 26b of this Comparative Example 3-1 to the area of the second electrode sheet 26 of this embodiment, that is, the opening ratio, is 20%.

[0419] In this Comparative Example 3-1, the resin constituting the filament 71 is PET (polyethylene terephthalate), and the diameter of the filament 71 is 10 to 20 μm. The metal constituting the coating layer 33 has a three-layer structure, with the outermost layer being Ni, the intermediate layer being Cu, and the innermost layer (on the side of the filament 71b) being Ni. The diameter of the warp filament aggregate 72a is approximately 70 μm, and the diameter of the weft filament aggregate 72b is approximately 70 μm.

[0420] As shown in Fig.37As shown, a coating layer 33 is formed on at least a part of the surface of the untwisted yarn bundle 74b that constitutes the warp fiber aggregate 72ab and the weft fiber aggregate 72bb. In this embodiment, the coating layer 33 is formed over the entire circumference of the surface of the untwisted yarn bundle 74b.

[0421] By bringing the coating layer 33 of the warp fiber aggregate 72ab into contact with the coating layer 33 of the weft fiber aggregate 72bb, the warp fiber aggregate 72ab and the weft fiber aggregate 72bb are electrically connected.

[0422] The configuration other than the above is the same as that of Example 3-1, and thus the repeated description is omitted.

[0423] In addition, in this Comparative Example 3-1, the insulating sheet 24 is an ether-based polyurethane foam. The first joint portion 36 is an acrylic adhesive manufactured by NOGAWA CHEMICAL Co., Ltd. The thickness of the first joint portion 36 is 50 μm. The first joint portion 36 is the same as the second joint portion 37, and thus the repeated description is omitted. Similar to Sample 3-1, a sample 3-3 of the sensor sheet 18 related to the first electrode sheet 25b and the second electrode sheet 26b of Comparative Example 3-1 was fabricated. The description repeated with Sample 3-1 is omitted.

[0424] 3.1.7.4. Tensile Test of the First Electrode Sheet

[0425] Next, with reference to Fig.38 , the tensile test performed on the first electrode sheet will be described. The first electrode sheets related to Examples 3-1 to 3-2 and Comparative Example 3-1 were cut into strips of 150 mm × 20 mm to fabricate test pieces. The thicknesses of the first electrode sheets were different in Examples 3-1 to 3-2 and Comparative Example 3-1, but were approximately 0.1 mm. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a was set to 45°.

[0426] The test piece was held by a pair of chucks. The distance between the pair of chucks was 70 mm. A tensile test was performed on the test piece at a tensile speed of 1 mm / sec, and the stress was calculated by dividing the load by the cross-sectional area of the test piece. The tensile testing machine was AGS-X 1 kN manufactured by Shimadzu Corporation. The tensile test was performed in the range where the strain was 0 to 20%. The Fig.38 shows a graph of the change in stress with respect to strain.

[0427] In Examples 3-1 and 3-2, in the region where the strain was 0 to 20%, the stress slowly and monotonically increased. In the stress-strain curves of Examples 3-1 and 3-2 in the tensile test, there was no yield point showing a maximum value in the interval where the strain was 0.5 to 10%.

[0428] Example 3-1 shows a stress of approximately 1.4 MPa at a strain of 5% and a stress of approximately 7.5 MPa at a strain of 20%. Example 3-2 shows a stress of approximately 0.9 MPa at a strain of 5% and a stress of approximately 5.9 MPa at a strain of 20%. For the first electrode sheets 25 and 25a related to Example 3-1 and Example 3-2, the maximum value of the stress at a strain of 0 to 5% is 3 MPa or less, and the maximum value of the stress at a strain of 0 to 20% is 15 MPa or less.

[0429] In the stress-strain curve of Comparative Example 3-1 in the tensile test, there is a yield point showing a maximum value in the range of a strain of 0.5 to 10%. In the region where the strain is 0 to approximately 1%, the stress linearly and monotonically increases. When the strain is approximately 1%, the stress shows a maximum value of approximately 17 MPa and sharply decreases to approximately 12 MPa. Thus, in Comparative Example 3-1, before and after the strain of approximately 1%, the tendency of the stress changes from an increasing tendency to a decreasing tendency. After that, in the region where the strain is approximately 1 to approximately 13%, the stress monotonically decreases to approximately 12 to approximately 10 MPa. After that, in the region where the strain is approximately 13 to 20%, the stress monotonically increases to approximately 10 to approximately 12 MPa. Thus, in Comparative Example 3-1 in the stress-strain curve, the maximum value of the stress at a strain of 0 to 5% is greater than 3 MPa, and the maximum value of the stress at a strain of 0 to 20% is greater than 15 MPa.

[0430] 3.1.7.5. Tensile Test of Sensor Sheet

[0431] Next, the tensile test performed on the sensor sheet will be described. The sensor sheets related to Samples 3-1 to 3-2 and Sample 3-3 were cut into strips of 90 mm × 20 mm to fabricate test pieces. The thickness of the sensor sheet is different in Samples 3-1 to 3-2 and Sample 3-3, but is approximately 1 mm. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a constituting the first electrode sheet and the second electrode sheet is set to 45°.

[0432] A wire is connected to one end of the first electrode sheet in the length direction and connected to a DC power supply. A wire is connected to the other end of the first electrode sheet in the length direction and connected to a voltage measuring device.

[0433] The test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. The tensile test is performed on the test piece at a tensile speed of 1 mm / sec, and the stress is calculated by dividing the load by the cross-sectional area of the test piece. In addition, during the tensile test, the DC resistance value (an example of the resistance value) of the sensor sheet is calculated based on the voltage of the DC power supply and the voltage drop of the sensor sheet.

[0434] Fig.39The figure shows a stress-strain curve in a tensile test performed on the sensor sheet. Fig.39 The graph shows the region of strain of 0 to 20%. The stress of samples 3-1 and 3-2 increases monotonically in the region of strain of 0 to 20%. In the stress-strain curves of samples 3-1 and 3-2 in the tensile test, there is no yield point showing a maximum value in the region of strain of 0.5 to 10%.

[0435] Sample 3-1 shows a stress of about 0.5 MPa when the strain is 5%, and shows a maximum stress of about 2.6 MPa when the strain is 20%. Sample 3-2 shows a stress of about 0.3 MPa when the strain is 5%, and shows a maximum stress of about 1.5 MPa when the strain is 20%. In the stress-strain curves of Samples 3-1 and 3-2, the maximum stress value is less than 0.5 MPa when the strain is 0 to 5%, and the maximum stress value is less than 3 MPa when the strain is 0 to 20%. In the stress-strain curves of Samples 3-1 and 3-2, the stress value is less than 0.5 MPa when the strain is 0 to 5%, and the maximum stress value is less than 3 MPa when the strain is 0 to 20%.

[0436] In the stress-strain curve of sample 3-3 in the tensile test, there is a yield point showing a maximum value in the interval of strain of 0.5 to 10%. In the region of strain of 0 to about 3%, the stress increases linearly and monotonically. When the strain is about 3%, the stress shows about 0.7MPa as a maximum value, and decreases sharply to about 0.6MPa. In this way, in sample 3-3, before and after the strain is about 3%, the stress changes from an increasing tendency to a decreasing tendency. Afterwards, in the region of strain of about 1 to about 13%, the stress decreases slightly. Then, in the region of strain of about 13 to 20%, the stress increases monotonically to about 0.6 to about 0.8MPa. In this way, in the stress-strain curve of sample 3-3, the maximum value of stress when the strain is 0 to 5% is greater than 0.5MPa, and the maximum value of stress when the strain is 0 to 20% is greater than 0.7MPa.

[0437] When a tensile force is applied to Samples 3-1 and 3-2, the first opening 34a of the first electrode sheet stretches in the tensile direction and contracts in a direction intersecting the tensile direction. Fig.40 In the example, sample 3-2 is taken as an example to show the deformation state of the first opening 34a. Fig.40 As shown in (a) in FIG. 1 , when the elongation is 0%, the first opening 34a is open, but as the elongation increases to 10% (see FIG. 1 ), the first opening 34a is open. Fig.40 (b) in), 20% (refer to Fig.40 (c)), 30% (refer to Fig.40In (d) thereof, the gaps between the fibers of the conductive cloth are reduced, and in a state where the elongation rate is 30%, the first opening 34a almost disappears. It is considered that due to such a change in the fiber shape, it can be easily elongated, so the stress generated during elongation is small. That is, it is considered that the existence of the first opening 34a contributes to the structural stretching flexibility of the fiber. The above configuration is the same for the second electrode sheet, so the description is omitted. It should be noted that the same applies to Sample 3-1, so the description is omitted.

[0438] It is considered that in Sample 3-1 and Sample 3-2, when a tensile force is applied to the sensor sheet, the first opening 34a gradually deforms, and thus the tensile force is absorbed. As a result, at the intersection of the warp filament aggregate 72a and the weft filament aggregate 72b, the relative positions of the warp filament aggregate 72a and the weft filament aggregate 72b do not change significantly, so it is considered that the electrical connection state between the warp filament aggregate 72a and the weft filament aggregate 72b can be maintained. Thus, it is considered that in Sample 3-1 and Sample 3-2, even when a tensile force is applied to the sensor sheet, the DC resistance value hardly changes.

[0439] In addition, Sample 3-1 and Sample 3-2 do not have a yield point showing a maximum value in the strain range of 0.5 to 5%. It is considered that this is because in the strain range of 0.5 to 5% for Sample 3-1 and Sample 3-2, the structure of the plating layer 33 formed on the first electrode sheet and the second electrode sheet does not change significantly. As a result, the change in the resistance value of the sensor sheet 18 is suppressed.

[0440] On the other hand, Sample 3-3 has a yield point showing a maximum value in the strain range of 0.5 to 5%. In Sample 3-3, it is considered that in the strain range from 0% to the yield point, the plating layer 33 formed at the intersection of the warp filament aggregate 72a and the weft filament aggregate 72b is maintained, and thus elastic deformation occurs. It is considered that after that, at the yield point, the plating layer 33 formed at the intersection of the warp filament aggregate 72a and the weft filament aggregate 72b is damaged.

[0441] After that, in the range where the stress hardly changes (the strain range of about 5 to about 15%), similar to Sample 3-1 and Sample 3-2, it is considered that the tensile force is absorbed by deforming the first opening 34a and the second opening 34b.

[0442] It is considered that if the strain becomes larger than about 15% thereafter, the first opening ratio and the second opening ratio of Sample 3-3 are 20%, so the first opening 34a and the second opening 34b are completely blocked, and the tensile force acting on the first electrode sheet and the second electrode sheet cannot be absorbed. Thus, it is considered that the stress increases.

[0443] 3.1.7.6. Change Rate of DC Resistance Value of Sensor Sheet

[0444] Next, for the sensor sheet, the change rate of the DC resistance value is measured. The sensor sheet is cut into a strip of 90 mm × 20 mm to make a test piece. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a is set to 45°.

[0445] The test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec. Wires are connected to both end portions of the first electrode sheet, and the DC resistance value between the two wires is measured. Regarding the DC resistance value at this time, based on the following formula (1), the change rate of the DC resistance value is calculated. The measurement of the DC resistance value uses the digital multimeter 2000 series manufactured by KEITHLEY. The above tests are performed on Samples 3-1 to 3-2 and Sample 3-3.

[0446] [Equation 2]

[0447]

[0448] Fig.41 It is a graph showing the change of the DC resistance value change rate with respect to strain. The DC resistance value change rate of Sample 3-1 increases in the range where the strain is 0 to about 2%, and in the state where the strain is about 2%, the DC resistivity change rate is about 5%. After that, it decreases in the range of about 2 to about 5%, and the DC resistivity change rate becomes about 0%. After that, when the strain is 25% or more, the DC resistance value change rate slowly increases, and the DC resistance value change rate becomes about 7% when the strain is 30%. Thus, the DC resistance value change rate of Sample 3-1 is 10% or less in the range where the strain is 0 to 30%.

[0449] The DC resistance value change rate of Sample 3-2 increases in the range where the strain is 0 to about 3%, and in the state where the strain is about 3%, the DC resistivity change rate is about 10%. After that, it decreases in the range of about 3 to about 5%, and the DC resistivity change rate becomes about 0%. After that, even when the strain is 30%, the DC resistance value change rate is about 0%. Thus, the DC resistance value change rate of Sample 3-2 is 10% or less in the range where the strain is 0 to 30%.

[0450] The DC resistance value change rate of Sample 3-3 is about 2% in the range where the strain is 0 to about 3%. After that, in the range where the strain is about 3 to 30%, the DC resistance value change rate monotonically increases, and when the strain is 30%, the DC resistance value change rate is about 130%. Thus, the DC resistance value change rate of Sample 3-3 is greater than 10% in the range where the strain is 0 to 30%, and the resistance change during elongation is extremely large compared to Sample 3-1 and Sample 3-2.

[0451] 3.1.7.7.10% elongation rate of DC resistance value of sensor sheet

[0452] Next, for the sensor sheet, the DC resistance value change rate at 10% elongation is measured. The sensor sheet is cut into a strip of 90 mm × 20 mm to make a test piece. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a is set to 45°.

[0453] A pair of chucks is used to hold the test piece. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec. Wires are connected to both end portions of the first electrode sheet, and the DC resistance value between the two wires is measured. Regarding the DC resistance value at this time, based on the following formula (1), the DC resistance value change rate is calculated. The measurement of the DC resistance value uses the digital multimeter 2000 series manufactured by KEITHLEY. The above tests are performed on samples 3-1 to 3-2 and sample 3-3.

[0454] When measuring the DC resistance value change rate of the above sensor sheet, the following test is repeated a predetermined number of times: After the sensor sheet is elongated by 10% with respect to the reference length (50 mm) in the state before the tensile force is applied to the sensor sheet, it is restored to the reference length and elongated by 10% again. The number of repetitions in this test is 1 time, 5 times, and 10 times. Regarding the DC resistance value at this time, based on the above formula (1), the DC resistance value change rate is calculated. The above tests are performed on samples 3-1 to 3-2 and sample 3-3.

[0455] Fig.42 A graph showing the relationship between the number of repetitions of the elongation test and the DC resistance value change rate. The DC resistance value change rate at the first measurement of sample 3-1 is about 0%. After that, as the number of repetitions increases, the DC resistance value change rate increases. It is about 36% at 1 repetition, about 48% at 5 repetitions, and about 57% at 10 repetitions. At 10 repetitions, the DC resistivity change rate of sample 3-1 is 60% or less.

[0456] The DC resistivity change rate at the first measurement of sample 3-2 is about 14%, which is larger than that of sample 3-1. However, it is about 9% at 1 repetition, about 15% at 5 repetitions, and the DC resistance value change rate does not increase much even as the number of repetitions increases. It is about 30% at 10 repetitions. At 10 repetitions, the DC resistance value change rate of sample 3-2 is 50% or less.

[0457] The rate of change of the DC resistance value during the initial measurement of Sample 3-3 was the same as that of Sample 3-1, at approximately 0%. However, it was approximately 61% after 1 repetition, approximately 89% after 5 repetitions, and approximately 115% after 10 repetitions. As the number of repetitions increased, the rate of change of the DC resistance value increased compared to Samples 3-1 and 3-2.

[0458] As described above, it can be seen that even when the 10% elongation test was repeated, the change in the DC resistance value of the sensor chips related to Samples 3-1 and 3-2 was small compared to Sample 3-3.

[0459] 3.1.7.8. Rate of change of the DC resistance value of the sensor chip at 20% elongation

[0460] Next, for Samples 3-1 to 3-2 and Sample 3-3, the rate of change of the DC resistance value when the sensor chip was elongated by 20% was measured.

[0461] Fig.43 A graph showing the relationship between the number of repetitions of the elongation test and the rate of change of the DC resistance value. The rate of change of the DC resistance value during the initial measurement of Sample 3-1 was approximately 0%. After that, it was approximately 35% after 1 repetition and approximately 91% after 5 repetitions. As the number of repetitions increased, the rate of change of the DC resistance value increased. At 10 repetitions, the rate of change of the DC resistance value was approximately 137%.

[0462] The rate of change of the DC resistivity during the initial measurement of Sample 3-2 was approximately 10%, which was larger than that of Sample 3-1. However, it was approximately 27% after 1 repetition and approximately 32% after 5 repetitions. Even when the number of repetitions increased, the rate of change of the DC resistance value did not increase much. At 10 repetitions, the rate of change of the DC resistance value of Sample 3-2 was approximately 55%.

[0463] The rate of change of the DC resistance value during the initial measurement of Sample 3-3 was approximately 0%, the same as that of Sample 3-1. However, it showed approximately 114% after 1 repetition and exceeded 200% after 5 repetitions.

[0464] As described above, it can be seen that even when the 20% elongation test was repeated, the change in the DC resistance value of the sensor chips related to Samples 3-1 and 3-2 was small compared to Sample 3-3.

[0465] 3.1.8. Effects of this embodiment

[0466] Next, the effects of this embodiment will be described. The sensor sheet 18 according to this embodiment includes an insulating sheet 24, a first electrode sheet 25, a first electrode sheet 25a, a first joint portion 36, a second electrode sheet 26, and a second joint portion 37. The insulating sheet 24 has a first surface 27 and a second surface 28 and is formed of a foam. The first electrode sheet 25 and the first electrode sheet 25a have conductivity and are disposed on the first surface 27 side of the insulating sheet 24 and have a first opening 34a that penetrates therethrough. The first joint portion 36 joins the insulating sheet 24 to the first electrode sheet 25 and the first electrode sheet 25a. The second electrode sheet 26 has conductivity and is disposed on the second surface 28 side of the insulating sheet 24 and has a second opening 34b that penetrates therethrough. The second joint portion 37 joins the insulating sheet 24 to the second electrode sheet 26. The first electrode sheet 25, the first electrode sheet 25a, and the second electrode sheet 26 are conductive cloths formed by weaving a plurality of filament aggregates 72. The filament aggregate 72 includes a plurality of filaments 71 and a plating layer 33 formed on at least a part of the surface of the filaments 71. The first electrode sheet 25 and the first electrode sheet 25a have a first opening 34a that opens between the plurality of filament aggregates 72, and the second electrode sheet 26 has a second opening 34b that opens between the plurality of filament aggregates 72. The sensor sheet 18 is configured such that in the stress-strain curve in a tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%. The ratio of the opening area of the first opening 34a to the area of the first electrode sheet 25 and the first electrode sheet 25a, that is, the opening ratio, is 1% or more and 40% or less. The ratio of the opening area of the second opening 34b to the area of the second electrode sheet 26 and the second electrode sheet 26a, that is, the opening ratio, is 1% or more and 40% or more.

[0467] When a tensile force is applied to the sensor sheet 18, the first opening 34a of the first electrode sheet 25 and the first electrode sheet 25a deforms in such a manner that the opening area of the first opening 34a decreases. In addition, a new conduction path is formed between the plurality of filament aggregates 72 separated by the first opening 34a. Thus, even when a tensile force is applied to the sensor sheet 18, a change in the resistance value can be suppressed. It should be noted that the same applies to the second opening 34b of the second electrode sheet 26 and the second electrode sheet 26a.

[0468] The opening ratio of the first opening portion 34a is preferably 1% or more and 40% or less. By setting the opening ratio to 40% or less, when the first opening portion 34a is deformed in the direction of decreasing the opening area, the plurality of filament aggregates 72 are likely to come into contact with each other. Thus, since the plurality of filament aggregates 72 are likely to come into contact with each other, the opening ratio of the first opening portion 34a is preferably 1% or more and 40% or less, more preferably 1% or more and 30% or less, and still more preferably 1% or more and 20% or less. However, the same applies to the second opening portion 34b.

[0469] The sensor sheet 18 according to this embodiment is configured such that in the stress-strain curve in the tensile test, there is no yield point showing a maximum value in the strain range of 0.5% to 10%. Thus, in a region where the strain is relatively small, such as 0.5 to 10%, no large stress is generated, and a sharp change in stress is suppressed. As a result, the efficiency of the operation of assembling the sensor sheet 18 to the steering wheel 10 can be improved. In addition, by not having a yield point showing a maximum value in the strain range of 0.5 to 5%, when the sensor sheet 18 is slightly stretched, no large stress is generated and the stress does not change, so the workability is further improved, which is more preferable.

[0470] When a tensile force is applied to the sensor sheet 18, the first opening portion 34a of the first electrode sheet 25 is deformed in such a manner that the opening area of the first opening portion 34a decreases. That is, the tensile strain does not concentrate on the filaments 71 themselves, and elongation can be achieved by changing the spatial arrangement of the entire filaments 71. That is, by reducing the opening area associated with the change in the spatial arrangement of the entire filaments 71, the structural stretching flexibility is exhibited, so the elongation strain applied to the filaments 71 themselves is small, and damage to the plating layer 33 formed on the filaments 71 can be suppressed. Thus, even when a tensile force is applied to the sensor sheet 18, a change in the resistance value can be suppressed.

[0471] In addition, the sensor sheet 18 according to this embodiment is configured such that in the stress-strain curve in the tensile test, there is no yield point showing a maximum value in the strain range of 0.5 to 10%, so the breakage of the plating layer 33 in the strain range of 0.5 to 10% can be suppressed. Thus, a change in the resistance value of the sensor sheet 18 can be suppressed.

[0472] The sensor chip 18 involved in this method is configured such that in the stress-strain curve, the maximum value of the stress when the strain is 0 to 5% is 0.5 MPa or less. In addition, the sensor chip 18 is configured such that in the stress-strain curve, the maximum value of the stress when the strain is 0 to 20% is 3 MPa or less. Thus, when a tensile force is applied to the sensor chip 18, it is possible to suppress the situation where excessive stress is applied to the first electrode chip 25 and the first electrode chip 25a. As a result, it is possible to suppress the situation where the structure of the first electrode chip 25 and the first electrode chip 25a is damaged, and thus it is possible to suppress the change in the resistance value of the sensor chip 18.

[0473] From the viewpoint of reducing the stress applied to the first electrode chip 25 and the first electrode chip 25a, or from the viewpoint of reducing the stress applied to the second electrode chip 26 and the second electrode chip 26a, in the stress-strain curve, the maximum value of the stress of the sensor chip 18 when the strain is 0 to 5% is preferably 0.5 MPa or less, more preferably 0.4 MPa or less, and further preferably 0.3 MPa or less.

[0474] Similarly, from the viewpoint of reducing the stress applied to the first electrode chip 25 and the first electrode chip 25a, or from the viewpoint of reducing the stress applied to the second electrode chip 26 and the second electrode chip 26a, in the stress-strain curve, the maximum value of the stress of the sensor chip 18 when the strain is 0 to 20% is preferably 3 MPa or less, more preferably 2 MPa or less, and further preferably 1.5 MPa or less.

[0475] In addition, the first electrode chip 25 and the first electrode chip 25a involved in this method are configured such that in the stress-strain curve, the maximum value of the stress when the strain is 0 to 5% is 3 MPa or less. In addition, the first electrode chip 25 and the first electrode chip 25a are configured such that in the stress-strain curve, the maximum value of the stress when the strain is 0 to 20% is 15 MPa or less. It should be noted that the same applies to the second electrode chip 26 and the second electrode chip 26a.

[0476] From the viewpoint of reducing the stress applied to the first electrode chip 25 and the first electrode chip 25a, or from the viewpoint of reducing the stress applied to the second electrode chip 26 and the second electrode chip 26a, in the stress-strain curve, the maximum value of the stress of the first electrode chip 25 and the first electrode chip 25a or the second electrode chip 26 and the second electrode chip 26a when the strain is 0 to 5% is preferably 3 MPa or less, more preferably 2 MPa or less, and further preferably 1 MPa or less.

[0477] Similarly, from the viewpoint of reducing the stress applied to the first electrode sheets 25 and 25a, or from the viewpoint of reducing the stress applied to the second electrode sheets 26 and 26a, the maximum value of the stress of the first electrode sheets 25 and 25a or the second electrode sheets 26 and 26a when the strain is 0 to 20% is preferably 15 MPa or less, more preferably 10 MPa or less, and further preferably 7 MPa or less.

[0478] The stress-strain curve of the sensor sheet 18 according to this embodiment is the stress-strain curve in the case where a test piece of 20 mm × 90 mm is held and a tensile test is performed at a tensile speed of 1 mm / s.

[0479] The sensor sheet 18 according to this embodiment is configured such that when the strain in the tensile test is 20%, the DC resistor change rate defined by Equation (1) is 50% or less.

[0480] [Equation 3]

[0481]

[0482] Herein, the difference in the DC resistance values before and after elongation is the difference obtained by subtracting the initial DC resistance value before elongation from the DC resistance value after elongation.

[0483] According to this embodiment, even when the sensor sheet 18 is elongated, it is possible to suppress a change in the DC resistance value. Thus, it is possible to suppress a change in the resistance value of the sensor sheet 18. The DC resistor change rate is preferably 50% or less, more preferably 30% or less, and further preferably 11% or less.

[0484] The sensor sheet 18 according to this embodiment is configured such that the DC resistor change rate defined by Equation (1) is 150% or less after repeating the test of setting the strain to 20% and then returning the strain to 0% 10 times.

[0485] [Equation 4]

[0486]

[0487] Herein, the difference in the DC resistance values before and after elongation is the difference obtained by subtracting the initial DC resistance value before elongation from the DC resistance value after elongation.

[0488] According to this embodiment, even when the operation of returning to the original size is repeated after the sensor sheet 18 is elongated, it is possible to suppress a change in the DC resistance value. Thus, it is possible to suppress a change in the resistance value of the sensor sheet 18. The DC resistor change rate is preferably 150% or less, more preferably 140% or less, and further preferably 100% or less.

[0489] The cross-sectional area of each of the plurality of filament aggregates 72 according to this embodiment is larger than the opening area of the first opening 34a in a state where the first electrode sheet 25 and the first electrode sheet 25a are not strained. As a result, the proportion of the filament aggregate 72 in the unit area becomes larger, and thus more conductive paths are formed in the first electrode sheet 25 and the first electrode sheet 25a. As a result, even when a tensile force is applied to the sensor sheet 18 and several of the plurality of conductive paths are damaged, conductive paths that can conduct electricity can be retained. Thereby, a change in the resistance value of the sensor sheet 18 can be suppressed. In addition, the cross-sectional area of each of the plurality of filament aggregates 72 is larger than the opening area of the second opening 34b in a state where the second electrode sheet 26 and the second electrode sheet 26a are not strained. The effects are the same as those of the first electrode sheet 25 and the first electrode sheet 25a, and thus the description thereof is omitted.

[0490] In addition, the plurality of filament aggregates 72 according to this embodiment include a warp filament aggregate 72a and a weft filament aggregate 72b, and the area of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other is larger than the opening area of the first opening 34a in a state where the first electrode sheet 25 and the first electrode sheet 25a are not strained. It should be noted that, with respect to the second electrode sheet 26 and the second electrode sheet 26a, the area of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other is also larger than the opening area of the second opening 34b in a state where the second electrode sheet 26 and the second electrode sheet 26a are not strained.

[0491] At the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically conductive. Therefore, at the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other, a plating layer 33 is formed on the portion exposed to the outside. On this basis, in the portion closer to the inside (the inside of the crossing), the more the area where the plating layer 33 is formed, the easier it is for the warp filament aggregate 72a and the weft filament aggregate 72b to be electrically conductive. Therefore, according to this embodiment, even when a tensile force is applied to the sensor sheet 18, the electrical conductivity between the warp filament aggregate 72a and the weft filament aggregate 72b can be maintained. As a result, a change in the resistance value of the sensor sheet 18 can be suppressed.

[0492] The sensor sheet 18 according to this embodiment further includes conductive second electrode sheets 26 and 26a on the second surface 28 of the insulating sheet 24. By including the second electrode sheets 26 and 26a, the sensor sheet 18 can be electromagnetically shielded, and thus the sensitivity of the sensor sheet 18 can be improved.

[0493] The plurality of filament aggregates 72 involved in this method include a warp filament aggregate 72a and a weft filament aggregate 72b. The warp filament aggregate 72a and the weft filament aggregate 72b include a twistless yarn bundle 74 formed by aggregating a plurality of filaments 71 in an untwisted state and a plating layer 33 formed on at least a part of the surface of the twistless yarn bundle 74.

[0494] Since the filament aggregate 72 is a twistless yarn bundle 74, the plurality of filaments 71 constituting the filament aggregate 72 are formed in a configuration that allows them to move relatively freely. Therefore, even when a tensile force is applied to the sensor sheet 18, by moving the plurality of filaments 71 constituting the twistless yarn bundle 74, stress can be absorbed. As a result, the situation where excessive stress is applied to the sensor sheet 18 is suppressed, and thus the situation where the resistance value of the sensor sheet 18 changes can be suppressed.

[0495] In the filament aggregate 72 involved in this method, there are also portions where the plating layers 33 formed on the surfaces of adjacent filaments 71 are in contact with each other and electrically connected on the outer surfaces of the plurality of filaments 71 located inside the twistless yarn bundle 74 formed in a bundle shape. Therefore, when a tensile force is applied to the sensor sheet 18, even if the plating layer 33 formed on the outer surface of the filaments 71 located on the surface of the twistless yarn bundle 74 breaks, there is still the plating layer 33 formed on the outer surfaces of the plurality of filaments 71 located inside the twistless yarn bundle 74. As a result, the plating layers 33 formed on the outer surfaces of the plurality of filaments 71 located inside the twistless yarn bundle 74 come into contact with each other, and thus even when a tensile force is applied to the sensor sheet 18, a change in the resistance value can be suppressed.

[0496] (Embodiment 3-2)

[0497] Next, with reference to Figures 44 to 47 , Embodiment 3-2 will be described. Among the reference numerals used after Embodiment 3-2, the same reference numerals as those used in the already presented embodiments represent the same constituent elements, etc., unless otherwise specifically indicated.

[0498] 3.2.1. Configuration of the first electrode sheet 25c

[0499] As Fig.44As shown, the first electrode sheet 25c according to Embodiment 3-2 includes a warp filament aggregate 72a and a weft filament aggregate 72b. As described above, the warp filament aggregate 72a and the weft filament aggregate 72b include a non-twisted yarn wire bundle 74 formed by bundling a plurality of filaments 71 in an untwisted state and a plating layer 33 formed on the surface of the non-twisted yarn wire bundle 74. It should be noted that although not shown in detail, the sensor sheet 18 according to this embodiment includes a second electrode sheet on the second surface side of the insulating sheet 24. The configuration of the second electrode sheet is substantially the same as that of the first electrode sheet 25c, so repeated description is omitted.

[0500] As the metal constituting the plating layer 33, any metal or alloy such as copper, nickel, tin, solder, etc. can be appropriately selected. The metal constituting the plating layer 33 is the same as that in Embodiment 3-1, so repeated description is omitted.

[0501] In this embodiment, the metal types of the plating layers 33 constituting the plurality of warp filament aggregates 72a are the same as the metal types of the plating layers 33 constituting the plurality of weft filament aggregates 72b. However, the metal types of the plating layers 33 constituting the plurality of warp filament aggregates 72a and the metal types of the plating layers 33 constituting the plurality of weft filament aggregates 72b can also be different. In addition, the metal types of the plating layers 33 constituting the plurality of warp filament aggregates 72a can also be different in the arrangement direction of the plurality of warp filament aggregates 72a. In addition, the metal types of the plating layers 33 constituting the plurality of weft filament aggregates 72b can also be different in the arrangement direction of the plurality of weft filament aggregates 72b. In addition, among at least two of the plurality of warp filament aggregates 72a, the metal types of the plating layers 33 formed on the plurality of filaments 71 constituting each warp filament aggregate 72a can be different. In addition, among at least two of the plurality of weft filament aggregates 72b, the metal types of the plating layers 33 formed on the plurality of filaments 71 constituting each weft filament aggregate 72b can also be different.

[0502] By making the metal types different, the properties (electrical properties, chemical properties, mechanical properties, etc.) of the plating layers 33 of the plurality of warp filament aggregates 72a can be made different from the properties (electrical properties, chemical properties, mechanical properties, etc.) of the plurality of weft filament aggregates 72b. As electrical properties, examples include resistance value. As chemical properties, examples include ionization tendency, affinity, etc. As mechanical properties, examples include friction coefficient, strength, elongation, etc. The ratio of the opening area of the first opening 34a formed in the first electrode sheet 25c of this embodiment to the area of the first electrode sheet 25c, that is, the opening ratio, is 30% or more. However, the value of the opening ratio is not particularly limited, and it can also be less than 30%.

[0503] As Fig.44As shown, each warp filament aggregate 72a includes a plurality of filaments 71. The number of filaments 71 that make up one warp filament aggregate 72a is not particularly limited.

[0504] As Fig.44 shown, each weft filament aggregate 72b includes a plurality of filaments 71.

[0505] As Fig.47 shown, the longitudinal directions S of the plurality of warp filament aggregates 72a are arranged to cross the longitudinal direction X of the first electrode plate 25c. In addition, the longitudinal directions T of the plurality of weft filament aggregates 72b are arranged to cross the longitudinal direction X of the first electrode plate 25c. Specifically, the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode plate 25c is substantially 45°. In addition, the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode plate 25c is substantially 45°. The same applies to the second electrode plate.

[0506] As Fig.45 shown, a coating layer 33 is formed on at least a part of the surface of each filament 71 that makes up the warp filament aggregate 72a. The coating layer 33 can be formed on the entire surface of each filament 71 that makes up the warp filament aggregate 72a, or can be formed on a part of the surface of each filament 71 that makes up the warp filament aggregate 72a. In this embodiment, except for the warp filament contact points 71aa where adjacent filaments 71 contact each other, the coating layer 33 is formed on the surface of each filament 71. In this embodiment, the coating layer 33 is also formed on the surface of the filaments 71 in the region located inside one warp filament aggregate 72a. Adjacent filaments 71 are electrically connected through the coating layer 33 in the region exposed on the surface of the first electrode plate 25c.

[0507] As Fig.46 shown, a coating layer 33 is formed on at least a part of the surface of each filament 71 that makes up the weft filament aggregate 72b. The coating layer 33 can be formed on the entire surface of each filament 71 that makes up the weft filament aggregate 72b, or can be formed on a part of the surface of each filament 71 that makes up the weft filament aggregate 72b. In this embodiment, except for the weft filament contact points 71ab where adjacent filaments 71 contact each other, the coating layer 33 is formed on the surface of each filament 71. In this embodiment, the coating layer 33 is also formed on the surface of the filaments 71 in the region located inside one weft filament aggregate 72b. Adjacent filaments 71 are electrically connected through the coating layer 33 in the region exposed on the surface of the first electrode plate 25c.

[0508] In addition, in this method, a coating layer 33 is formed on the surface of each filament 71, except at the weft filament contact point 71ab where the filaments 71 constituting the warp filament aggregate 72a come into contact with the filaments 71 constituting the weft filament aggregate 72b. The warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected through the coating layer 33.

[0509] 3.2.2. Relationship between the first electrode piece 25c and the narrow portion 35

[0510] 3.2.2.1. As Fig.47 shown, a region of the first electrode piece 25c sandwiched between two recesses 30 formed at overlapping positions in the crossing direction Y is formed as a narrow portion 35 that is narrower in the crossing direction Y than other portions. In the narrow portion 35, the occupied area when projecting a plurality of warp filament aggregates 72a in the thickness direction Z of the narrow portion 35 is larger than the occupied area when projecting a plurality of weft filament aggregates 72b in the thickness direction Z of the narrow portion 35.

[0511] 3.2.2.2. In the narrow portion 35, the interval between adjacent weft filament aggregates 72b is smaller than the interval between adjacent warp filament aggregates 72a.

[0512] 3.2.2.3. The number of filaments 71 constituting the warp filament aggregate 72a in the narrow portion 35 is larger than the number of filaments 71 constituting the warp filament aggregate 72a in a portion different from the narrow portion 35.

[0513] 3.2.2.4. The number of filaments 71 constituting the weft filament aggregate 72b in the narrow portion 35 is larger than the number of filaments 71 constituting the weft filament aggregate 72b in a portion different from the narrow portion 35.

[0514] The configurations described in 3.2.2.1. to 3.2.2.4. above are independent of each other, and may have all the configurations described in 3.2.2.1. to 3.2.2.4., or may have at least one selected from the configurations described in 3.2.2.1. to 3.2.2.4. In addition, the configurations described in 3.2.2.1. to 3.2.2.4. may be omitted.

[0515] 3.2.3. Relationship between the first electrode piece 25c and the extension portion 31

[0516] As described above, in the first electrode piece 25c of this method, the acute angle of the length direction S of a plurality of warp filament aggregates 72a with respect to the length direction X of the first electrode piece 25c is substantially 45°, and the acute angle of the length direction T of a plurality of weft filament aggregates 72b with respect to the length direction X of the first electrode piece 25c is substantially 45°. In Fig.47In [the figure], the extending directions of the plurality of warp filament aggregates 72a and the plurality of weft filament aggregates 72b of the first electrode sheet 25c are schematically shown using a pattern in which the lattice pattern is inclined at an angle of 45° obliquely.

[0517] 3.2.3.1. As Fig.47 shown, in the extension portions 31a and 31b of the first electrode sheet 25c, formed in Fig.47 the left side, the angle α formed by the extension direction E1 of the extension portion 31a and the length direction S of the plurality of warp filament aggregates 72a is smaller than the angle β formed by the extension direction E1 of the extension portion 31a and the length direction T of the plurality of weft filament aggregates 72b.

[0518] 3.2.3.2. As Fig.47 shown, in the extension portion 31 of the first electrode sheet 25c, formed in Fig.47 the right side, the angle α formed by the extension direction E2 of the extension portion 31b and the length direction S of the plurality of warp filament aggregates 72a is larger than the angle β formed by the extension direction E2 of the extension portion 31b and the length direction T of the plurality of weft filament aggregates 72b. The same applies to the second electrode sheet.

[0519] 3.2.3.3. In the extension portion 31 of the first electrode sheet 25c, the occupied area when the plurality of warp filament aggregates 72a are projected in the thickness direction Z of the extension portion 31 is larger than the occupied area when the plurality of weft filament aggregates 72b are projected in the thickness direction Z of the extension portion 31.

[0520] 3.2.3.4. In the extension portion 31 of the first electrode sheet 25c, the interval between adjacent filaments 71 of the weft filament aggregate 72b is smaller than the interval between adjacent filaments 71 of the warp filament aggregate 72a.

[0521] 3.2.3.5. The number of the plurality of filaments 71 constituting the warp filament aggregate 72a in the extension portion 31 of the first electrode sheet 25c is larger than the number of the plurality of filaments 71 constituting the warp filament aggregate 72a in a portion different from the extension portion 31.

[0522] 3.2.3.6. The number of the plurality of filaments 71 constituting the weft filament aggregate 72b in the extension portion 31 of the first electrode sheet 25c is larger than the number of the plurality of filaments 71 constituting the weft filament aggregate 72b in a portion different from the extension portion 31.

[0523] The configurations described in 3.2.3.1. to 3.2.3.6. above are independent of each other, and may have all the configurations described in 3.2.3.1. to 3.2.3.6., or may have at least one selected from the configurations described in 3.2.3.1. to 3.2.3.6. In addition, the configurations described in 3.2.3.1. to 3.2.3.6. may be omitted. The same applies to the second electrode sheet.

[0524] 3.2.4. Bending Test

[0525] When the first electrode sheet 25c is subjected to a bending test at an angle of 135° using a jig with a load of 50 g and R0.38 mm in accordance with JIS P8115:2001, the increase rate of the resistance value after 1000 cycles is preferably 50% or less, more preferably 50% or less after 2000 cycles, further preferably 50% or less after 5000 cycles, and particularly preferably 50% or less after 10000 cycles. Thus, a sensor sheet 18 can be obtained in which an increase in the resistance value is suppressed even when an external force is applied.

[0526] 3.2.5. Effects of this Embodiment

[0527] Next, the effects of this embodiment will be described. The first electrode sheet 25c related to the sensor sheet 18 of this embodiment is a conductive cloth having a plurality of warp filament aggregates 72a each having a plurality of filaments 71 and a plurality of weft filament aggregates 72b each having a plurality of filaments 71. A plating layer 33 made of metal is formed on the surface of each filament 71.

[0528] According to this embodiment, when an external force is applied to the sensor sheet 18, even when the plating layer 33 peels off and the conduction path from one end portion to the other end portion of one filament 71 is disconnected, the possibility that the conduction paths of other filaments 71 remain is increased. In addition, even when the conduction path between one filament 71 and other filaments 71 is disconnected, the possibility that the conduction paths between any other filaments 71 remain is increased. As a result, even when an external force is applied to the sensor sheet 18, the possibility that the conduction paths between the plurality of filaments 71 constituting the sensor sheet 18 remain can be increased, and thus an increase in the resistance value of the sensor sheet 18 when an external force is applied can be suppressed.

[0529] In addition, the plurality of warp filament aggregates 72a involved in this method are arranged at equal intervals from each other, and the plurality of weft filament aggregates 72b are arranged at different intervals. The strength of the first electrode sheet 25c can be increased by the plurality of warp filament aggregates 72a arranged at equal intervals, and the stretchability of the first electrode sheet 25c can be increased by the plurality of weft filament aggregates 72b arranged at different intervals.

[0530] Adjacent filaments 71 constituting the warp filament aggregate 72a involved in this method are electrically connected by the plating layer 33 in the region exposed on the surface of the first electrode sheet 25c. Thereby, the plurality of filaments 71 constituting the warp filament aggregate 72a can be electrically connected to each other.

[0531] Adjacent filaments 71 constituting the weft filament aggregate 72b involved in this method are electrically connected by the plating layer 33 in the region exposed on the surface of the first electrode sheet 25c. Thereby, the plurality of filaments 71 constituting the weft filament aggregate 72b can be electrically connected to each other.

[0532] As Fig.45 shown, in this method, the filaments 71 constituting the warp filament aggregate 72a are in contact with each other at the warp filament contact point 71aa (an example of a filament contact point). In addition, as Fig.46 shown, the filaments 71 constituting the weft filament aggregate 72b are in contact with each other at the weft filament contact point 71ab (an example of a filament contact point). In addition, as Fig.45 well as Fig.46 shown, the filaments 71 constituting the warp filament aggregate 72a and the filaments 71 constituting the weft filament aggregate 72b are in contact with each other at the warp and weft filament contact point 71ac (an example of a filament contact point). According to this method, in addition to the warp filament contact point 71aa, the weft filament contact point 71ab, and the warp and weft filament contact point 71ac, the plating layer 33 is formed on the surfaces of the plurality of filaments 71. Thereby, even when an external force is applied to the sensor sheet 18, the possibility of the conduction path of the plurality of filaments 71 constituting the sensor sheet 18 being maintained can be increased. Thereby, an increase in the resistance value of the sensor sheet 18 when an external force is applied to the sensor sheet 18 can be suppressed.

[0533] 3.2.6.1. The first electrode sheet 25c involved in this method has a narrow-width portion 35 that is narrower in width in the crossing direction Y that crosses the length direction X of the first electrode sheet 25c than other portions. In the narrow-width portion 35, the occupied area when projecting a plurality of warp filament aggregates 72a in the thickness direction Z of the narrow-width portion 35 is larger than the occupied area when projecting a plurality of weft filament aggregates 72b in the thickness direction Z of the narrow-width portion 35. According to this method, by making the occupied area of the plurality of warp filament aggregates 72a in the narrow-width portion 35 larger than the occupied area of the plurality of weft filament aggregates 72b, the strength of the narrow-width portion 35 can be improved.

[0534] 3.2.6.2. In the narrow-width portion 35 involved in this method, the interval between adjacent filaments 71 constituting the plurality of weft filament aggregates 72b is smaller than the interval between adjacent filaments 71 constituting the plurality of warp filament aggregates 72a. Since the narrow-width portion 35 is likely to be greatly deformed, a relatively large force is likely to be applied, and the coating 33 is likely to peel off. According to this method, by making the interval between the filaments 71 constituting the plurality of weft filament aggregates 72b smaller than the interval between the filaments 71 constituting the plurality of warp filament aggregates 72a, the conduction path between the filaments 71 constituting the weft filament aggregate 72b can be maintained.

[0535] 3.2.6.3. The number of the plurality of filaments 71 constituting the warp filament aggregate 72a in the narrow-width portion 35 involved in this method is larger than the number of the plurality of filaments 71 constituting the warp filament aggregate 72a in a portion different from the narrow-width portion 35. According to this method, by making the number of the plurality of filaments 71 constituting the warp filament aggregate 72a in the narrow-width portion 35 larger than that in other portions, the strength of the narrow-width portion 35 can be improved.

[0536] 3.2.6.4. The number of the plurality of filaments 71 constituting the weft filament aggregate 72b in the narrow-width portion 35 involved in this method is larger than the number of the plurality of filaments 71 constituting the weft filament aggregate 72b in a portion different from the narrow-width portion 35. According to this method, by making the number of the plurality of filaments 71 constituting the weft filament aggregate 72b in the narrow-width portion 35 larger than that in other portions, the strength of the narrow-width portion 35 can be improved.

[0537] 3.2.6.5. According to this mode, there are an extension part 31a extending in the extension direction E1 from the long side edge along the length direction X of the first electrode piece 25c and an extension part 31b extending in the extension direction E2. In the extension part 31a and the extension part 31b, the occupied area when the plurality of warp filament aggregates 72a are projected in the thickness direction Z of the extension part 31a and the extension part 31b is larger than the occupied area when the plurality of weft filament aggregates 72b are projected in the thickness direction Z of the extension part 31a and the extension part 31b. Thus, by making the occupied area of the plurality of warp filament aggregates 72a larger than that of the plurality of weft filament aggregates 72b, the strength of the extension part 31a and the extension part 31b can be improved.

[0538] 3.2.6.6. In the extension part 31a involved in this mode, the angle α formed by the extension direction E1 of the extension part 31a and the length direction S of the plurality of warp filament aggregates 72a is smaller than the angle β formed by the extension direction E1 of the extension part 31a and the length direction T of the plurality of weft filament aggregates 72b. According to this mode, the length direction S of the plurality of warp filament aggregates 72a can be arranged along the extension direction E1 of the extension part 31a. Thus, the strength of the extension part 31a can be improved.

[0539] 3.2.6.7. In the extension part 31b involved in this mode, the angle α formed by the extension direction E2 of the extension part 31b and the length direction S of the plurality of warp filament aggregates 72a is larger than the angle β formed by the extension direction E2 of the extension part 31b and the length direction T of the plurality of weft filament aggregates 72b. Thus, the length direction T of the plurality of weft filament aggregates 72b can be arranged along the extension direction E2 of the extension part 31b. Thus, the strength of the extension part 31b can be improved.

[0540] 3.2.6.8. In the extension part 31 involved in this mode, the interval between adjacent filaments 71 constituting the weft filament aggregate 72b is smaller than the interval between adjacent filaments 71 constituting the warp filament aggregate 72a. Since the extension part 31 is likely to be greatly deformed, a relatively large force is likely to be applied, and the coating 33 is likely to peel off. According to this mode, by making the interval between adjacent filaments 71 constituting the weft filament aggregate 72b smaller than the interval between adjacent filaments 71 constituting the warp filament aggregate 72a, the conduction path between the filaments 71 constituting the weft filament aggregate 72b can be maintained.

[0541] 3.2.6.9. The number of filaments 71 that make up the warp filament aggregate 72a in the extension part 31 involved in this method is larger than the number of filaments 71 that make up the warp filament aggregate 72a in the part different from the extension part 31. According to this method, by making the number of filaments 71 that make up the warp filament aggregate 72a in the extension part 31 larger than that in other parts, the strength of the extension part 31 can be improved.

[0542] 3.2.6.10. The number of filaments 71 that make up the weft filament aggregate 72b in the extension part 31 involved in this method is larger than the number of filaments 71 that make up the weft filament aggregate 72b in the part different from the extension part 31. According to this method, by making the number of filaments 71 that make up the weft filament aggregate 72b in the extension part 31 larger than that in other parts, the strength of the extension part 31 can be improved.

[0543] 3.2.6.11. The opening ratio, which is the ratio of the opening area of the first opening 34a of the first electrode sheet 25c to the area of the first electrode sheet 25c, involved in this method is 30% or more. Thereby, the stretchability of the first electrode sheet 25c can be improved.

[0544] The configurations described in 3.2.6.1. to 3.2.6.11. above are independent of each other, and all the configurations described in 3.2.6.1. to 3.2.6.11. can be provided, or at least one selected from the configurations described in 3.2.6.1. to 3.2.6.11. can be provided. In addition, the configurations described in 3.2.6.1. to 3.2.6.11. can also be omitted. The same applies to the second electrode sheet.

[0545] (Embodiment 3-3)

[0546] Next, with reference to Figure 48-49 , the first electrode sheet 25d of Embodiment 3-3 will be described. In Fig.48 , a partial enlarged view of the enlarged region R1 is also described.

[0547] As Fig.48 shown, in this method, at least a part of the filaments 71 that make up the plurality of warp filament aggregates 72a has warp filament opposing surfaces 71ba (an example of a filament opposing surface) that oppose each other. In this method, a coating layer 33 is formed on the warp filament opposing surface 71ba.

[0548] Among the plurality of filaments 71 that constitute the warp filament aggregate 72a, the plating layer 33 formed on the warp filament facing surface 71ba of one filament 71 is in contact with the plating layer 33 formed on the warp filament facing surface 71ba of another filament 71 adjacent to one filament 71. Thereby, the plurality of filaments 71 that constitute the warp filament aggregate 72a are electrically connected to each other.

[0549] In addition, Fig.49 also records a partial enlarged view of the enlarged area R2. As Fig.49 shown, in this embodiment, at least a part of the plurality of filaments 71 that constitute the weft filament aggregate 72b have weft filament facing surfaces 71bb that face each other. In this embodiment, a plating layer 33 is formed on the weft filament facing surface 71bb. The plating layers 33 formed on the weft filament facing surfaces 71bb of adjacent filaments 71 that constitute the weft filament aggregate 72b are in contact with each other, whereby the plurality of filaments 71 that constitute the weft filament aggregate 72b are electrically connected to each other.

[0550] In the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross and overlap, the filaments 71 exposed on the outer surface of the warp filament aggregate 72a and the filaments 71 exposed on the outer surface of the weft filament aggregate 72b have warp and weft filament facing surfaces 71bc (an example of a filament facing surface) that face each other. In this embodiment, a plating layer 33 is formed on the warp and weft filament facing surface 71bc. Thereby, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected.

[0551] In this embodiment, at least a part of the plurality of filaments 71 located inside the warp filament aggregate 72a among the plurality of filaments 71 that constitute the warp filament aggregate 72a have warp filament facing surfaces 71ba that face each other, and a plating layer 33 is formed on the warp filament facing surface 71ba.

[0552] By forming the plating layer 33 on the warp filament facing surface 71ba of the filament 71 located inside the warp filament aggregate 72a, even when an external force is applied to the sensor chip 18, the situation where the external force directly acts on the warp filament facing surface 71ba can be suppressed. As a result, the possibility of the plating layer 33 formed on the facing surface remaining is increased. Thereby, even when an external force is applied to the sensor chip 18, the possibility of the conduction path of the warp filament aggregate 72a that constitutes the sensor chip 18 remaining can be increased, and thus the situation where the resistance value of the sensor chip 18 increases when an external force is applied to the sensor chip 18 can be suppressed.

[0553] In this mode, the plating layer 33 formed on the warp filament facing surface 71ba of one filament 71 among the multiple filaments 71 constituting the warp filament aggregate 72a comes into contact with the plating layer 33 formed on the warp filament facing surface 71ba of another filament 71. According to this mode, the conduction path between one filament 71 and another filament 71 can be maintained, so that an increase in the resistance value of the sensor chip 18 when an external force is applied to the sensor chip 18 can be suppressed. It should be noted that the weft filament aggregate 72b can also achieve the same effect as the warp filament aggregate 72a, so the repeated description is omitted.

[0554] In this mode, one filament 71 among the multiple filaments 71 constituting the warp filament aggregate 72a and one filament 71 among the multiple filaments 71 constituting the weft filament aggregate 72b have the warp and weft filament facing surfaces 71bc facing each other, and the plating layer 33 is formed on the warp and weft filament facing surface 71bc.

[0555] Since the warp and weft filament facing surface 71bc is entirely located inside the first electrode piece 25d, even when an external force is applied to the sensor chip 18, the possibility of maintaining the conduction path between the filaments 71 constituting the warp filament aggregate 72a and the filaments 71 constituting the weft filament aggregate 72b that make up the sensor chip 18 can be increased, so that an increase in the resistance value of the sensor chip 18 when an external force is applied to the sensor chip 18 can be suppressed.

[0556] In this mode, the plating layer 33 formed on the warp filament facing surface 71ba of one filament 71 constituting the warp filament aggregate 72a comes into contact with the plating layer 33 formed on the warp filament facing surface 71ba of one filament 71 constituting the weft filament aggregate 72b. According to this mode, the conduction path between the warp filament aggregate 72a and the weft filament aggregate 72b can be maintained, so that an increase in the resistance value of the sensor chip 18 when an external force is applied to the sensor chip 18 can be suppressed. It should be noted that the weft filament aggregate 72b can also achieve the same effect as the warp filament aggregate 72a, so the repeated description is omitted.

[0557] If the state in which the user's hand is in contact with the steering wheel 10 continues, the steering wheel is placed in a high-temperature and high-humidity state. If the high-temperature and high-humidity state continues for a long time, there is a risk that the coating 33 formed on the surface of the filaments 71 exposed on the outer surfaces of the warp filament aggregate 72a and the weft filament aggregate 72b will be damaged. According to this aspect, since the coating 33 is formed on the warp filament opposing surface 71ba, the weft filament opposing surface 71bb, and the warp and weft filament opposing surface 71bc, even if the coating 33 formed on the surface of the filaments 71 exposed on the outer surfaces of the warp filament aggregate 72a and the weft filament aggregate 72b is damaged, the coating 33 formed on the warp filament opposing surface 71ba, the weft filament opposing surface 71bb, and the warp and weft filament opposing surface 71bc is not easily damaged. Thereby, an increase in the resistance value of the sensor piece 18 can be suppressed. It should be noted that the same effect can also be obtained for the second electrode piece, so the repeated description is omitted.

[0558] (Example 3-4)

[0559] Next, refer to Fig.50 to describe Embodiment 3-4.

[0560] (a) In the first electrode piece 25e of this aspect, the number of the filaments 71 constituting the plurality of warp filament aggregates 72a is different in the arrangement direction of the plurality of warp filament aggregates 72a.

[0561] (b) Further, in this aspect, the intervals between adjacent warp filament aggregates 72a are different in the direction in which the plurality of warp filament aggregates 72a are arranged.

[0562] (c) In this aspect, the number of the filaments 71 constituting the plurality of warp filament aggregates 72a is different in the arrangement direction of the plurality of warp filament aggregates 72a. By making the strengths of the plurality of warp filament aggregates 72a different in this way, the strength of the first electrode piece 25e can be easily changed locally.

[0563] (d) In this aspect, the plurality of warp filament aggregates 72a are arranged at intervals, and the intervals between adjacent warp filament aggregates 72a are different in the direction in which the plurality of warp filament aggregates 72a are arranged. By changing the intervals between the plurality of warp filament aggregates 72a in this way, the stretchability of the first electrode piece 25e can be easily changed.

[0564] The configurations described in (a) to (d) above are independent of each other. It may have all the configurations described in (a) to (d), or may have at least one selected from the configurations described in (a) to (d). In addition, the configurations described in (a) to (d) may be omitted. It should be noted that the second electrode sheet can also be configured in the same way as the first electrode sheet 25e, so repeated descriptions are omitted.

[0565] (Embodiment 3-5)

[0566] Next, refer to Fig.51 to describe Embodiment 3-5.

[0567] (e) In the first electrode sheet 25f of this embodiment, the number of filaments 71 that make up the plurality of weft filament aggregates 72b is different in the arrangement direction of the plurality of weft filament aggregates 72b.

[0568] (f) In addition, in this embodiment, the intervals between adjacent weft filament aggregates 72b are different in the direction in which the plurality of weft filament aggregates 72b are arranged.

[0569] (g) In this embodiment, the number of filaments 71 that make up the plurality of weft filament aggregates 72b is different in the arrangement direction of the plurality of weft filament aggregates 72b. By making the strengths of the plurality of weft filament aggregates 72b different in this way, it is possible to easily locally change the strength of the first electrode sheet 25f.

[0570] (h) In this embodiment, the plurality of weft filament aggregates 72b are arranged at intervals, and the intervals between adjacent weft filament aggregates 72b are different in the arrangement direction of the plurality of weft filament aggregates 72b. By changing the intervals between the plurality of weft filament aggregates 72b in this way, it is possible to easily change the stretchability of the first electrode sheet 25f.

[0571] The configurations described in (e) to (h) above are independent of each other. It may have all the configurations described in (e) to (h), or may have at least one selected from the configurations described in (e) to (h). In addition, the configurations described in (e) to (h) may be omitted. It should be noted that the second electrode sheet can also have the same configuration as the first electrode sheet 25f, so repeated descriptions are omitted.

[0572] (Embodiment 3-6)

[0573] Next, refer to Fig.52 to describe Embodiment 3-6.

[0574] In the first electrode sheet 25g of this embodiment, the number of filaments 71 that make up the warp filament aggregate 72a is different from the number of filaments 71 that make up the weft filament aggregate 72b. Thereby, the strength of the warp filament aggregate 72a can be made different from the strength of the weft filament aggregate 72b. As a result, the strength of the first electrode sheet 25 can be easily changed locally. The number of filaments 71 that make up the warp filament aggregate 72a may be more than the number of filaments 71 that make up the weft filament aggregate 72b. In addition, the number of filaments 71 that make up the warp filament aggregate 72a may be less than the number of filaments 71 that make up the weft filament aggregate 72b. It should be noted that the second electrode sheet can also be configured in the same way as the first electrode sheet 25g, so repeated descriptions are omitted.

[0575] (Embodiment 3-7)

[0576] Next, refer to Fig.53 to describe Embodiment 3-7. In the first electrode sheet 25h of this embodiment, the weft filament aggregate 72b includes a twisted yarn 73 formed by twisting a plurality of filaments 71 and a plating layer 33 formed on the surface of the twisted yarn 73. The twisted yarn 73 is formed by twisting a plurality of filaments 71.

[0577] According to this embodiment, by the weft filament aggregate 72b having the twisted yarn 73, plating is performed while ensuring the contact pressure between the warp filament aggregate 72a and the weft filament aggregate 72b. Therefore, the contact pressure at the contact points of each of the plurality of warp filament aggregates 72a and the plurality of weft filament aggregates 72b is further increased, and an increase in the resistance value of the sensor sheet 18 can be suppressed.

[0578] However, it may also be configured such that the warp filament aggregate 72a includes a twisted yarn 73 and a plating layer 33, and the weft filament aggregate 72b includes an untwisted yarn bundle 74 and a plating layer 33. However, the second electrode sheet also has the same configuration as the first electrode sheet 25h, so repeated descriptions are omitted.

[0579] (Embodiment 3-8)

[0580] Next, refer to Fig.54 to describe Embodiment 3-9. In the sensor sheet 18 of this embodiment, the two sheet extension portions 22 formed on the sensor sheet 18 are formed in parallel. That is, the two sheet extension portions 22 extend in the same extension direction E1. The extension portion 31 formed on the first electrode sheet 25h is also formed to extend in the same extension direction E1.

[0581] In this mode, the angle α formed by the longitudinal direction S of the plurality of warp filament aggregates 72a of the first electrode sheet 25i and the extension direction E1 of the extension portion 31 is smaller than the angle β formed by the longitudinal direction T of the plurality of weft filament aggregates 72b of the first electrode sheet 25f and the extension direction E1 of the extension portion 31.

[0582] According to this mode, the longitudinal direction S of the plurality of warp filament aggregates 72a can be arranged along the extension direction E1 of the extension portion 31. Thereby, the strength of the extension portion 31 can be improved. It should be noted that the second electrode sheet can also have the same configuration as the first electrode sheet 25f, so repeated descriptions are omitted.

[0583] (Embodiment 3-9)

[0584] Refer to Fig.55 , and Embodiment 3-9 will be described. In the sensor sheet 18 of this mode, on the first surface 27 of the insulating sheet 24, two first electrode sheets 25j and 25k are arranged along the length direction X of the insulating sheet 24. Although not shown in detail, on the second surface 28 of the insulating sheet 24, two second electrode sheets are arranged along the length direction X of the insulating sheet 24.

[0585] In this mode, the longitudinal direction S1 of the plurality of warp filament aggregates 72a of the first electrode sheet 25j arranged on the Fig.55 left side is orthogonal to the longitudinal direction S2 of the plurality of warp filament aggregates 72a of the first electrode sheet 25k arranged on the Fig.55 right side. In addition, the longitudinal direction T1 of the plurality of weft filament aggregates 72b of the first electrode sheet 25j arranged on the Fig.55 left side is orthogonal to the longitudinal direction T2 of the plurality of weft filament aggregates 72b of the first electrode sheet 25k arranged on the Fig.55 right side.

[0586] In this mode, the angle α formed by the longitudinal direction S1 of the warp filament aggregate 72a of the first electrode sheet 25i and the extension direction E1 of the extension portion 31 is smaller than the angle β formed by the longitudinal direction T1 of the weft filament aggregate 72b of the first electrode sheet 25j and the extension direction E1 of the extension portion 31.

[0587] In addition, the angle α formed by the longitudinal direction S2 of the plurality of warp filament aggregates 72a of the first electrode sheet 25k and the extension direction E2 of the extension portion 31b is smaller than the angle β formed by the longitudinal direction T2 of the plurality of weft filament aggregates 72b of the first electrode sheet 25j and the extension direction E2 of the extension portion 31b.

[0588] According to this method, the longitudinal direction S1 of the plurality of warp filament aggregates 72a can be arranged along the extending direction E1 of the extending portion 31a. Thereby, the strength of the extending portion 31a can be improved. In addition, the longitudinal direction S2 of the plurality of warp filament aggregates 72a can be arranged along the extending direction E2 of the extending portion 31b. Thereby, the strength of the extending portion 31b can be improved. It should be noted that the second electrode sheet can also have the same configuration as the first electrode sheet 25i, so repeated descriptions are omitted.

[0589] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist thereof.

[0590] As Fig.56 shown, it may be configured such that the first electrode sheet 25 is disposed on the first surface 27 of the insulating sheet 24, and the second electrode sheet 26 is not disposed on the second surface 28 of the insulating sheet 24.

[0591] (Embodiment 4-1)

[0592] Next, Embodiment 4-1 will be described. Embodiment 4-1 has the same configuration as that described in 1.1.1 to 1.1.4 of Embodiment 1-1. Therefore, the descriptions of 1.1.1 to 1.1.4 are replaced with 4.1.1 to 4.1.4, and repeated descriptions are omitted.

[0593] 4.1.5. Bonding structure between the first electrode sheet 25 and the second electrode sheet 26 and the insulating sheet 24

[0594] As Fig.57 shown, on the first surface 27 side of the insulating sheet 24, the insulating sheet 24 and the first electrode sheet 25 are bonded through a first bonding portion 36 interposed between the insulating sheet 24 and the first electrode sheet 25. The material constituting the first bonding portion 36 is not particularly limited, and can be appropriately selected from any materials such as acrylic adhesives, silicone adhesives, urethane adhesives, and rubber-based adhesives. In addition, as Fig.57 shown, on the second surface 28 side of the insulating sheet 24, the insulating sheet 24 and the second electrode sheet 26 are bonded through a second bonding portion 37 interposed between the insulating sheet 24 and the second electrode sheet 26. The material constituting the second bonding portion 37 is the same as that of the first bonding portion 36, so repeated descriptions are omitted.

[0595] 4.1.6. Protection portion 60

[0596] As Fig.57As shown, a first protection part 61 is disposed on the surface (outer surface) of the first electrode sheet 25. The first protection part 61 is formed to cover the surface of the first electrode sheet 25 in a layered manner. Further, a second protection part 62 is disposed on the surface (outer surface) of the second electrode sheet 26. The second protection part 62 is formed to cover the surface of the second electrode sheet 26 in a layered manner. In the following description, when not distinguishing between the first protection part 61 and the second protection part 62, it is sometimes referred to as the protection part 60.

[0597] The protection part 60 is configured to include a resin material or a rubber material. The material forming the protection part 60 is not particularly limited, and any material such as polyolefins such as polyethylene and polypropylene, polyesters such as polybutylene terephthalate and polyethylene terephthalate, polyamides such as nylon 6 and nylon 66, polyurethanes, and silicone polymers can be appropriately selected, but acrylic materials, urethane materials, and silicone materials are preferred.

[0598] In addition to the resin material, the protection part 60 may include additive materials such as antioxidants, and may also include fillers and the like.

[0599] The first protection part 61 disposed on the first electrode sheet 25 and the second protection part 62 disposed on the second electrode sheet 26 may be formed of the same material or different materials.

[0600] The first electrode sheet 25 and the first protection part 61 may also be configured to be integrally formed with the first electrode sheet 25 by the adhesiveness of the first protection part 61. Further, it may be configured to integrally form the first electrode sheet 25 and the first protection part 61 by thermally welding the first protection part 61 to the first electrode sheet 25. In addition, it may be configured to be integrally formed by bonding the first electrode sheet 25 and the first protection part 61 using an adhesive. The adhesive may be a known adhesive, or a material the same as that forming the above-described first joint part 36 may be applied.

[0601] Regarding the configuration of integrally forming the second electrode sheet 26 and the second protection part 62, it may be the same as or different from the configuration of integrally forming the first electrode sheet 25 and the first protection part 61.

[0602] 4.1.7. Configuration of Electrode Sheets

[0603] The first electrode sheet 25 and the second electrode sheet 26 will be described. The first electrode sheet 25 and the second electrode sheet 26 are conductive cloths having conductivity. The first electrode sheet 25 and the second electrode sheet 26 have conductivity and flexibility. The first electrode sheet 25 and the second electrode sheet 26 have stretchability in the length direction X and the crossing direction Y.

[0604] As Fig.58As shown, the first electrode sheet 25 and the second electrode sheet 26 are conductive cloths formed by weaving a plurality of fibril aggregates 72. The fibril aggregate 72 includes a plurality of fibrils 71 and a plating layer 33 formed on at least a part of the surface of the fibrils 71.

[0605] As Fig.58 shown in (a) to Fig.58 shown in (b) of the figure, the first electrode sheet 25 and the second electrode sheet 26 are manufactured by forming a plating layer 33 on a base cloth formed by weaving a plurality of untwisted yarn bundles 74. Each untwisted yarn bundle 74 is formed by gathering a plurality of fibrils 71 in an untwisted state.

[0606] Examples of the resin constituting the fibrils 71 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyamides such as nylon 6 and nylon 66. However, the resin constituting the fibrils 71 is not limited to the above, and any resin can be appropriately selected. The second electrode sheet 26 also has the same configuration.

[0607] The plating layer 33 is formed on the surface of a base cloth formed by weaving a plurality of fibril aggregates 72. The method of forming the plating layer 33 is not particularly limited. For example, it can be electroplating, electroless plating, or electroless plating can be performed after electroplating, or electroplating can be performed after electroless plating. Any method can be appropriately selected.

[0608] As the metal constituting the plating layer 33 formed on the surface of the base cloth, any metal or alloy such as copper, nickel, tin, and solder can be appropriately selected. The plating layer 33 formed on the surface of the base cloth can be composed of one metal or multiple metals. For example, only copper can be plated on the surface of the base cloth, only nickel can be plated on the surface of the base cloth, or a copper plating layer composed of copper can be formed on the surface of the base cloth, and a nickel plating layer composed of nickel can be formed on the surface of the copper plating layer. The plating layer 33 formed on the surface of the base cloth can be formed by electroplating or electroless plating. The second electrode sheet 26 also has the same configuration.

[0609] As Fig.58 shown in (a) of the figure, the first electrode sheet 25 has a first opening 34a that opens between a plurality of fibril aggregates 72. The first opening 34a penetrates the first electrode sheet 25. The ratio of the opening area of the first opening 34a formed in the first electrode sheet 25 to the area of the first electrode sheet 25, that is, the first opening ratio, is 1% or more and 40% or less.

[0610] As Fig.58As shown in (b) thereof, the second electrode sheet 26 has a second opening 34b that opens between a plurality of filament aggregates 72. The second opening 34b penetrates the second electrode sheet 26. The ratio of the opening area of the second opening 34b formed in the second electrode sheet 26 to the area of the second electrode sheet 26, that is, the second opening ratio, is 1% or more and 40% or less.

[0611] 4.1.8. Examples and Samples

[0612] 4.1.8.1. Example 4-1 and Sample 4-1

[0613] (Example 4-1 and Sample 4-1)

[0614] Refer to Figure 58-59 , and Example 4-1 will be described. As Fig.58 shown in (a) thereof, the first electrode sheet 25 according to Example 4-1 is a conductive cloth formed by weaving a plurality of filament aggregates 72. The plurality of filament aggregates 72 include an untwisted yarn wire bundle 74 formed by gathering a plurality of filaments 71 in an untwisted state and a plating layer 33 formed on at least a part of the surface of the untwisted yarn wire bundle 74. The filament aggregate 72 is formed in a flat shape in the thickness direction of the first electrode sheet 25. However, since the first electrode sheet 25 and the second electrode sheet 26 have substantially the same configuration, repeated descriptions are omitted except in particularly mentioned cases.

[0615] The first electrode sheet 25 according to this Example 4-1 is formed by weaving a warp filament aggregate 72a formed by gathering a plurality of filaments 71 in an untwisted state and a weft filament aggregate 72b formed by gathering a plurality of filaments 71 in an untwisted state to form a base cloth, and forming a plating layer 33 on the surface of the base cloth. However, the manufacturing method of the first electrode sheet 25 is not limited to the above method.

[0616] As Fig.58As shown in (a) of [reference], the first electrode sheet 25 of this method includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The first electrode sheet 25 has a first opening 34a that opens between the plurality of filament aggregates 72. The first opening 34a penetrates the first electrode sheet 25. In the present Example 4-1, the opening ratio, which is the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25 to the area of the first electrode sheet 25, is approximately 3%. It should be noted that this opening ratio is the ratio of the total opening area of the plurality of first openings 34a in the target area formed in the first electrode sheet 25 to the area of the target area of the first electrode sheet 25. This opening ratio is calculated, for example, by determining a 10 mm × 10 mm target area in the first electrode sheet 25, summing the areas of the first openings 34a within the target area, and dividing the total area by the area of the target area.

[0617] As Fig.58 As shown in (b) of [reference], the second electrode sheet 26 of this method includes a plurality of warp filament aggregates 72a and a plurality of weft filament aggregates 72b. The second electrode sheet 26 of this method has a second opening 34b that opens between the plurality of filament aggregates 72. The second opening 34b penetrates the second electrode sheet 26. In the present Example 4-1, the opening ratio, which is the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26 to the area of the second electrode sheet 26 of this method, is approximately 3%.

[0618] There is no particular limitation on the number of filaments 71 included in the filament aggregate 72 that constitutes the first electrode sheet 25. The filament aggregate 72 related to this method includes 75 filaments 71, but it can be set to any number. Additionally, regarding the second electrode sheet 26, it is the same as the first electrode sheet 25.

[0619] As Fig.59 As shown, a plating layer 33 is formed on at least a part of the surface of the untwisted yarn bundle 74 that constitutes the filament aggregate 72. By bringing the plating layer 33 of the warp filament aggregate 72a into contact with the plating layer 33 of the weft filament aggregate 72b, the warp filament aggregate 72a and the weft filament aggregate 72b are electrically connected.

[0620] As Fig.58As shown in (a) in [description], the longitudinal direction S of the plurality of warp filament aggregates 72a is arranged to intersect the longitudinal direction X of the first electrode plate 25. Further, the longitudinal direction T of the plurality of weft filament aggregates 72b is arranged to intersect the longitudinal direction X of the first electrode plate 25. Specifically, the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode plate 25 is substantially 45°. Further, the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode plate 25a is substantially 45°. The angle being substantially 45° includes the case of being 45°, and also includes the case that can be recognized as being substantially 45°. It should be noted that the second electrode plate 26 has the same configuration as the first electrode plate 25, and thus repeated description is omitted.

[0621] When the longitudinal direction S of the warp filament aggregate 72a is parallel to the longitudinal direction X of the first electrode plate 25 (when the acute angle is substantially 0°), if the first electrode plate 25 is elongated parallel to the direction X, the warp filament aggregate 72a itself will be stretched, and a large load is required.

[0622] On the other hand, when the longitudinal direction S of the warp filament aggregate 72a is inclined at an oblique angle of 45° with respect to the longitudinal direction X of the first electrode plate 25 (when the acute angle is substantially 45°), if the first electrode plate 25 is elongated parallel to the direction X, the square or rectangular lattice (the first opening 34a) formed by the warp filament aggregate 72a and the weft filament aggregate 72b is deformed into a rhombus shape, and the warp filament aggregate 72a or the weft filament aggregate 72b itself will not be stretched, so a large load is not required. That is, when the acute angle is substantially 45°, structural flexibility is imparted. Further, the higher the aperture ratio, the easier the square or rectangular lattice is deformed into a rhombus shape, and the structural flexibility is not easily impaired. The second electrode plate 26 is the same as the first electrode plate 25, and thus repeated description is omitted.

[0623] However, it may be that the acute angle of the longitudinal direction S of the plurality of warp filament aggregates 72a with respect to the longitudinal direction X of the first electrode plate 25 is an angle different from 45°. Further, it may be that the acute angle of the longitudinal direction T of the plurality of weft filament aggregates 72b with respect to the longitudinal direction X of the first electrode plate 25 is an angle different from 45°.

[0624] The number of filaments 71 constituting the warp filament aggregate 72a and the number of filaments 71 constituting the weft filament aggregate 72b may be the same or different. In the present Example 4-1, the number of filaments 71 constituting the warp filament aggregate 72a and the number of filaments 71 constituting the weft filament aggregate 72b are set to be substantially the same. Substantially the same includes the case of being the same, and also includes the case where it can be recognized as substantially the same even when they are not the same. The weft filament aggregate 72b is the same as the above, so repeated description is omitted. In the present Example 4-1, the number of filaments 71 is set to 75. However, the number of filaments 71 is not limited to the above number.

[0625] As Fig.59 shown, a coating layer 33 is formed on at least a part of the plurality of filaments 71 constituting the warp filament aggregate 72a. For example, the coating layer 33 is formed on the surface of the filaments 71 exposed on the outer surface of the warp filament aggregate 72a. The coating layer 33 is not formed on the surface of a part of the filaments 71 located inside the warp filament aggregate 72a. At the portion where the coating layer 33 is not formed, the surface of the filaments 71 is exposed. The weft filament aggregate 72b is the same as the above, so repeated description is omitted. However, the coating layer 33 may be formed on the surface of each of the plurality of filaments 71.

[0626] At the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other facing each other, the coating layer 33 is locally formed, and at the portion where the coating layer 33 is not formed, the surface of the filaments 71 is exposed. The coating layer 33 is formed in the region of the portion where the warp filament aggregate 72a and the weft filament aggregate 72b cross each other facing each other and is close to the portion exposed to the outside, and the coating layer 33 is not formed in the portion close to the inside. It should be noted that the weft filament aggregate 72b also has the same configuration as the warp filament aggregate 72a, so repeated description is omitted.

[0627] In the present Example 4-1, the resin constituting the filaments 71 is PET (polyethylene terephthalate), and the diameter of the filaments 71 is about 10 μm. The metal constituting the coating layer 33 is formed into a three-layer structure, the outermost layer is Ni, the intermediate layer is Cu, and the innermost layer (on the side of the filaments 71) is Ni. The diameter of the warp filament aggregate 72a is about 185 μm, and the diameter of the weft filament aggregate 72b is about 185 μm.

[0628] As Fig.57As shown in the figure, the above-described first electrode sheet 25 is joined to the first surface 27 of the insulating sheet 24 via the first joining portion 36. In addition, a second electrode sheet 26 having the same configuration as the first electrode sheet 25 is joined to the second surface 28 of the insulating sheet 24 via the second joining portion 37. The insulating sheet 24 is an ether-based polyurethane foam. The first joining portion 36 is an acrylic adhesive manufactured by NOGAWACHEMICAL Co., Ltd. The thickness of the first joining portion 36 is 50 μm. Since the first joining portion 36 is the same as the second joining portion 37, repeated descriptions are omitted.

[0629] The first protective portion 61 is arranged and formed integrally in such a manner that the surface of the first protective portion 61 is located on the outer surface of the first electrode sheet 25. The first electrode sheet 25 and the first protective portion 61 are formed integrally by an acrylic adhesive. The resin constituting the first protective portion 61 is an acrylic adhesive. The thickness of the first protective portion 61 is approximately 50 to 100 μm. Since the first protective portion 61 is the same as the second protective portion 62, repeated descriptions are omitted.

[0630] In this way, the sample 4-1 of the sensor sheet 18 related to the first electrode sheet 25 and the second electrode sheet 26 of Example 4-1 is produced.

[0631] 4.1.8.2. Example 4-2 and Sample 4-2

[0632] (Example 4-2 and Sample 4-2)

[0633] Next, with reference to Fig.60 in (a) to Fig.60 in (b), the configurations of the first electrode sheet 25a and the second electrode sheet 26a related to Example 4-2 will be described. In the first electrode sheet 25a related to this Example 4-2, the number of filaments 71a constituting the warp filament aggregate 72aa is different from the number of filaments 71a constituting the weft filament aggregate 72ba. In this Example 4-2, the number of filaments 71a constituting the warp filament aggregate 72aa is larger than the number of filaments 71a constituting the weft filament aggregate 72ba. However, it can also be configured such that the number of filaments 71a constituting the warp filament aggregate 72aa is smaller than the number of filaments 71a constituting the weft filament aggregate 72ba.

[0634] In the present Example 4-2, the number of filaments 71a constituting the warp filament aggregate 72aa is set to be approximately twice the number of filaments 71a constituting the weft filament aggregate 72ba. In the present Example 4-2, the number of filaments 71a constituting the warp filament aggregate 72aa is set to be approximately 80, and the number of filaments 71 constituting the weft filament aggregate 72ba is set to be approximately 40. However, the difference between the number of filaments 71a constituting the warp filament aggregate 72aa and the number of filaments 71a constituting the weft filament aggregate 72ba is not limited to the above.

[0635] The ratio of the opening area of the first opening 34a formed in the first electrode sheet 25a related to the present Example 4-2 to the area of the first electrode sheet 25a, that is, the opening ratio, is approximately 10%. In addition, the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26a to the area of the second electrode sheet 26a, that is, the opening ratio, is approximately 10%.

[0636] The second electrode sheet 26a has the same configuration as the first electrode sheet 25a, so redundant descriptions are omitted.

[0637] In the present Example 4-2, the resin constituting the filament 71a is PET (polyethylene terephthalate), and the diameter of the filament 71a is approximately 10 μm. The metal constituting the coating layer 33 has a single-layer structure and is a Ni single layer. The diameter of the warp filament aggregate 72a is approximately 180 μm, and the diameter of the weft filament aggregate 72b is approximately 90 μm.

[0638] The configurations other than the above are the same as those in Example 4-1, so redundant descriptions are omitted.

[0639] In addition, in the present Example 4-2, the insulating sheet 24 is an ether-based polyurethane foam. The first joint portion 36 is an acrylic-based adhesive. The thickness of the first joint portion 36 is approximately 50 μm. The first joint portion 36 is the same as the second joint portion 37, so redundant descriptions are omitted.

[0640] The first protection portion 61 is arranged so that the surface of the first protection portion 61 is located on the outer surface of the first electrode sheet 25a and is formed integrally. The first electrode sheet 25a and the first protection portion 61 are formed integrally by an acrylic-based adhesive. The resin constituting the first protection portion 61 is an acrylic-based adhesive. The thickness of the first protection portion 61 is approximately 50 to 100 μm. The first protection portion 61 is the same as the second protection portion 62, so redundant descriptions are omitted.

[0641] Except for the above, a sample 4-2 of the sensor sheet 18 related to the first electrode sheet of Example 4-2 is produced in the same manner as in Sample 4-1. Redundant descriptions identical to those in Sample 4-1 are omitted.

[0642] 4.1.8.3. Tensile Test of the First Electrode Sheet

[0643] Next, with reference to Fig.61 , the tensile test performed on the first electrode sheet will be described. The first electrode sheets involved in Examples 4-1 to 4-2 were cut into strips of 150 mm × 20 mm to produce test pieces. The thickness of the first electrode sheet was different in Examples 4-1 to 4-2, but was approximately 0.1 mm. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a was set to 45°.

[0644] The test piece was held by a pair of chucks. The distance between the pair of chucks was 70 mm. A tensile test was performed on the test piece at a tensile speed of 1 mm / sec, and the stress was calculated by dividing the load by the cross-sectional area of the test piece. The tensile testing machine was AGS-X1 kN manufactured by Shimadzu Corporation. The tensile test was performed in the range where the strain was 0 to 20%. In Fig.61 , a graph showing the change of stress with respect to strain is shown.

[0645] In Examples 4-1 and 4-2, in the region where the strain was 0 to 20%, the stress slowly and monotonically increased. In the stress-strain curves of Examples and 4-2 in the tensile test, there was no yield point showing a maximum value in the interval where the strain was 0.5 to 10%.

[0646] Example 4-1 showed a stress of approximately 1.4 MPa when the strain was 5%, and showed a stress of approximately 7.5 MPa when the strain was 20%. Example 4-2 showed a stress of approximately 0.9 MPa when the strain was 5%, and showed a stress of approximately 5.9 MPa when the strain was 20%. The maximum value of the stress of the first electrode sheets 25 and 25a involved in Example 4-1 and Example 4-2 was 3 MPa or less when the strain was 0 to 5%, and the maximum value of the stress was 15 MPa or less when the strain was 0 to 20%.

[0647] 4.1.8.4. Tensile Test of the Sensor Sheet

[0648] Next, the tensile test performed on the sensor sheet will be described. The sensor sheets involved in Samples 4-1 to 4-2 were cut into strips of 90 mm × 20 mm to produce test pieces. The thickness of the sensor sheet was different in Samples 4-1 to 4-2, but was approximately 1 mm. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a constituting the first electrode sheet and the second electrode sheet was set to 45°. It should be noted that in this test, the structure obtained by removing the first protection part 61 and the second protection part 62 from the structures of the above Samples 4-1 to 4-2 was used as the test piece.

[0649] A wire is connected to one end of the first electrode sheet in the longitudinal direction thereof and is connected to a DC power supply. A wire is connected to the other end of the first electrode sheet in the longitudinal direction thereof and is connected to a voltage measuring device.

[0650] A test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec, and the stress is calculated by dividing the load by the cross-sectional area of the test piece. In addition, during the tensile test, the DC resistance value (an example of the resistance value) of the sensor sheet is calculated based on the voltage of the DC power supply and the voltage drop of the sensor sheet.

[0651] Fig.62 The stress-strain curve in the tensile test performed on the sensor sheet is shown. Fig.62 The graph showing the region where the strain is 0 to 20% is shown. The stress of Samples 4-1 to 4-2 monotonically increases in the region where the strain is 0 to 20%. In the stress-strain curves of Sample 4-1 and Sample 4-2 in the tensile test, there is no yield point showing a maximum value in the interval where the strain is 0.5 to 10%.

[0652] Sample 4-1 shows a stress of about 0.5 MPa when the strain is 5%, and shows a stress of about 2.6 MPa as the maximum value of the stress when the strain is 20%. Sample 4-2 shows a stress of about 0.3 MPa when the strain is 5%, and shows a stress of about 1.5 MPa as the maximum value of the stress when the strain is 20%. In the stress-strain curves of Sample 4-1 and Sample 4-2, the maximum value of the stress when the strain is 0 to 5% is 0.5 MPa or less, and the maximum value of the stress when the strain is 0 to 20% is 3 MPa or less.

[0653] In the stress-strain curves of Sample 4-1 and Sample 4-2, the stress when the strain is 0 to 5% is 0.5 MPa or less, and the maximum value of the stress when the strain is 0 to 20% is 3 MPa or less.

[0654] When a tensile force is applied to Sample 4-1 and Sample 4-2, the first opening 34a of the first electrode sheet elongates in the tensile direction and contracts in the direction crossing the tensile direction. Fig.63 Taking Sample 4-2 as an example, the deformed state of the first opening 34a is shown. As Fig.63 shown in (a) thereof, in the state where the elongation rate is 0%, the first opening 34a is open, but as the elongation rate increases to 10% (refer to Fig.63 (b) thereof), 20% (refer to Fig.63 (c) thereof), 30% (refer to Fig.63In (d) thereof, the gaps between the fibers of the conductive cloth are reduced, and in a state where the elongation rate is 30%, the first opening 34a almost disappears. It is considered that due to such a change in the fiber shape, it can be easily elongated, so the stress generated during elongation is small. That is, it is considered that the presence of the first opening 34a contributes to the structural stretching flexibility of the fiber. The above configuration is the same for the second electrode sheet, so the description is omitted. It should be noted that the same applies to Sample 4-1, so the description is omitted.

[0655] It is considered that in Sample 4-1 and Sample 4-2, when a tensile force is applied to the sensor sheet, the first opening 34a gradually deforms, and thus the tensile force is absorbed. As a result, at the intersection of the warp filament aggregate 72a and the weft filament aggregate 72b, the relative positions of the warp filament aggregate 72a and the weft filament aggregate 72b do not change significantly, so it is considered that the electrical connection state between the warp filament aggregate 72a and the weft filament aggregate 72b can be maintained. Therefore, it is considered that in Sample 4-1 and Sample 4-2, even when a tensile force is applied to the sensor sheet, the DC resistance value hardly changes.

[0656] 4.1.8.5. Change Rate of DC Resistance Value of Sensor Sheet

[0657] Next, for the sensor sheet, the change rate of the DC resistance value was measured. The sensor sheet was cut into a long strip of 90 mm × 20 mm to make a test piece. The angle formed by the length direction of the test piece and the length direction of the warp filament aggregate 72a was set to 45°. It should be noted that in this test, the configuration obtained by removing the first protection part 61 and the second protection part 62 from the configurations of the above Samples 4-1 to 4-2 was used as the test piece.

[0658] The test piece was held by a pair of chucks. The distance between the pair of chucks was 50 mm. A tensile test was performed on the test piece at a tensile speed of 1 mm / sec. Wires were connected to both end portions of the first electrode sheet, and the DC resistance value between the two wires was measured. Regarding the DC resistance value at this time, based on the following formula (1), the change rate of the DC resistance value was calculated. The measurement of the DC resistance value was performed using a digital multimeter 2000 series manufactured by KEITHLEY. The above tests were performed on Samples 4-1 to 4-2.

[0659] [Equation 5]

[0660]

[0661] Fig.63It is a graph showing the change rate of the DC resistance value with respect to the strain. The change rate of the DC resistance value of Sample 4-1 increases in the range where the strain is from 0 to approximately 2%, and in the state where the strain is approximately 2%, the change rate of the DC resistivity is approximately 5%. After that, it decreases in the range from approximately 2% to approximately 5%, and the change rate of the DC resistivity becomes approximately 0%. After that, when the strain is 25% or more, the change rate of the DC resistance value increases slowly, and the change rate of the DC resistance value becomes approximately 7% when the strain is 30%. In this way, the change rate of the DC resistance value of Sample 4-1 is 10% or less in the range where the strain is from 0 to 30%.

[0662] The change rate of the DC resistance value of Sample 4-2 increases in the range where the strain is from 0 to approximately 3%, and in the state where the strain is approximately 3%, the change rate of the DC resistivity is approximately 10%. After that, it decreases in the range from approximately 3% to approximately 5%, and the change rate of the DC resistivity becomes approximately 0%. After that, even when the strain is 30%, the change rate of the DC resistance value is approximately 0%. In this way, the change rate of the DC resistance value of Sample 4-2 is 10% or less in the range where the strain is from 0 to 30%.

[0663] 4.1.8.6.10% Change Rate of the DC Resistance Value of the Sensor Chip at 10% Elongation

[0664] Next, for the sensor chip, the change rate of the DC resistance value at 10% elongation is measured. The sensor chip is cut into a strip shape of 90 mm × 20 mm to make a test piece. The angle formed by the length direction of the test piece and the length direction of the warp fiber aggregate 72a is set to 45°. It should be noted that in this test, the structure obtained by removing the first protective part 61 and the second protective part 62 from the structures of the above Samples 4-1 to 4-2 is used as the test piece.

[0665] The test piece is held by a pair of chucks. The distance between the pair of chucks is 50 mm. A tensile test is performed on the test piece at a tensile speed of 1 mm / sec. Wires are connected to both end portions of the first electrode piece, and the DC resistance value between the two wires is measured. Regarding the DC resistance value at this time, based on the following formula (1), the change rate of the DC resistance value is calculated. The measurement of the DC resistance value uses a digital multimeter 2000 series manufactured by KEITHLEY. The above tests are performed on Samples 4-1 to 4-2.

[0666] When measuring the change rate of the DC resistance value of the above sensor chip, the following test is repeated a predetermined number of times: After the sensor chip is elongated by 10% with respect to the reference length (50 mm) in the state before the tensile force is applied to the sensor chip, it is restored to the reference length, and then elongated by 10% again. The number of repetitions in this test is 1 time, 5 times, and 10 times. Regarding the DC resistance value at this time, based on the above formula (1), the change rate of the DC resistance value is calculated. The above tests are performed on Samples 4-1 to 4-2.

[0667] Fig.65 A graph showing the relationship between the number of repetitions of the elongation test and the rate of change of the DC resistance value. The rate of change of the DC resistance value at the first measurement of Sample 4-1 was approximately 0%. After that, as the number of repetitions increased, the rate of change of the DC resistance value increased. It was approximately 36% at 1 repetition, approximately 48% at 5 repetitions, and approximately 57% at 10 repetitions. At 10 repetitions, the rate of change of the DC resistivity of Sample 4-1 was 60% or less.

[0668] The rate of change of the DC resistivity at the first measurement of Sample 4-2 was approximately 14%, which was larger than that of Sample 4-1. However, it was approximately 9% at 1 repetition, approximately 15% at 5 repetitions, and the rate of change of the DC resistance value did not increase much even as the number of repetitions increased. It was approximately 30% at 10 repetitions. At 10 repetitions, the rate of change of the DC resistance value of Sample 4-2 was 50% or less. As described above, it can be seen that the change in the DC resistance value of the sensor chips related to Sample 4-1 and Sample 4-2 was small even when the 10% elongation test was repeated.

[0669] 4.1.8.7. Rate of change of DC resistance value of sensor chip at 20% elongation

[0670] Next, for Samples 4-1 to 4-2, the rate of change of the DC resistance value when the sensor chip was elongated by 20% was measured. It should be noted that in this test, the structure obtained by removing the first protection part 61 and the second protection part 62 from the structures of Samples 4-1 to 4-2 described above was used as the test piece.

[0671] Fig.66 A graph showing the relationship between the number of repetitions of the elongation test and the rate of change of the DC resistance value. The rate of change of the DC resistance value at the first measurement of Sample 4-1 was approximately 0%. After that, it was approximately 35% at 1 repetition and approximately 91% at 5 repetitions. As the number of repetitions increased, the rate of change of the DC resistance value increased. At 10 repetitions, the rate of change of the DC resistance value was approximately 137%.

[0672] The rate of change of the DC resistivity at the first measurement of Sample 4-2 was approximately 10%, which was larger than that of Sample 4-1. However, it was approximately 27% at 1 repetition and approximately 32% at 5 repetitions, and the rate of change of the DC resistance value did not increase much even as the number of repetitions increased. At 10 repetitions, the rate of change of the DC resistance value of Sample 4-2 was approximately 55%. As described above, it can be seen that the change in the DC resistance value of the sensor chips related to Sample 4-1 and Sample 4-2 was small even when the 20% elongation test was repeated.

[0673] 4.1.9. Modification example of Embodiment 4-1

[0674] Refer to Figure 67 to Figure 69, a modification of Embodiment 4-1 will be described. The configurations of the first electrode sheet 25c and the second electrode sheet 26c in this modification are different from those of Sample 4-1. As shown in (a) of Fig.67 , the first electrode sheet 25c of this modification includes a plurality of warp threads 41 and a plurality of weft threads 42. The first electrode sheet 25c is formed by weaving the warp threads 41 and the plurality of weft threads 42. Each warp thread 41 is composed of a single filament 71 and a plating layer 33 formed on the surface of the filament 71, and each weft thread 42 is composed of a single filament 71 and a plating layer 33 formed on the surface of the filament 71.

[0675] The first electrode sheet 25c has a first opening 34a that opens between two adjacent warp threads 41 among the plurality of warp threads 41 and two adjacent weft threads 42 among the plurality of weft threads 42. The first opening 34a penetrates the first electrode sheet 25c. In this modification, the opening ratio, which is the ratio of the opening area of the first opening 34a formed in the first electrode sheet 25c to the area of the first electrode sheet 25c, is approximately 63%.

[0676] As shown in (b) of Fig.67 , the second electrode sheet 26c of this modification includes a plurality of warp threads 41 and a plurality of weft threads 42. The second electrode sheet 26c is formed by weaving the warp threads 41 and the plurality of weft threads 42. Each warp thread 41 is composed of a single filament 71, and each weft thread 42 is composed of a single filament 71.

[0677] The second electrode sheet 26c has a second opening 34b that opens between two adjacent warp threads 41 among the plurality of warp threads 41 and two adjacent weft threads 42 among the plurality of weft threads 42. In this modification, the opening ratio, which is the ratio of the opening area of the second opening 34b formed in the second electrode sheet 26c to the area of the second electrode sheet 26c, is approximately 63%.

[0678] As shown in (a) of Fig.67 , the intervals between the plurality of warp threads 41 according to this modification are arranged to be substantially equidistant. However, substantially equidistant includes the case of equidistant, and also includes the case where it can be recognized as substantially equidistant even if it is not equidistant. In addition, the intervals between the plurality of warp threads 41 may be different.

[0679] In addition, the intervals between the plurality of weft threads 42 according to this modification are arranged to be substantially equidistant. However, substantially equidistant includes the case of equidistant, and also includes the case where it can be recognized as substantially equidistant even if it is not equidistant. In addition, the intervals between the plurality of weft threads 42 may be different.

[0680] As shown in (b) of Fig.67 , since the configuration of the second electrode sheet 26 is the same as that of the first electrode sheet 25, the repeated description is omitted.

[0681] As Fig.68 shown, a coating layer 33 is formed on at least a part of the warp 41. The coating layer 33 may be formed on the entire surface of the warp 41, or may be formed on a part of the surface of the warp 41.

[0682] In addition, a coating layer 33 is formed on at least a part of the weft 42. The coating layer 33 may be formed on the entire surface of the weft 42, or may be formed on a part of the surface of the weft 42.

[0683] In this modified example, the warp 41 and the weft 42 are electrically connected by bringing the coating layer 33 formed on the surface of the warp 41 into contact with the coating layer 33 formed on the surface of the weft 42.

[0684] When a tensile force is applied to this modified example, the first opening 34a of the first electrode piece 25 elongates in the tensile direction and contracts in a direction crossing the tensile direction. Fig.69 This shows the state in which the first opening 34a is deformed in this modified example. Thus, the tensile force is absorbed, and it is considered that the change in stress is small. It should be noted that the same applies to the second electrode piece 26, and thus repeated descriptions are omitted.

[0685] The configuration other than the above is the same as that of Sample 4-1, and thus repeated descriptions are omitted.

[0686] 4.1.10. Effects of this Embodiment

[0687] Next, the effects of this embodiment will be described. The sensor piece 18 according to this embodiment includes: an insulating sheet 24 having a first surface 27 and a second surface 28; a first electrode piece 25 disposed on the first surface 27 side of the insulating sheet 24 and made of conductive cloth; a first joint portion 36 that joints the first surface 27 of the insulating sheet 24 to the inner surface of the first electrode piece 25; and a first protection portion 61 disposed on the outer surface of the first electrode piece 25 to protect the outer surface of the first electrode piece 25.

[0688] According to this embodiment, the first protection portion 61 protects the first electrode piece 25 from external forces, and thus it is possible to suppress the case where the conduction path of the first electrode piece 25 is damaged. Thereby, it is possible to suppress a change in the resistance value of the sensor piece 18.

[0689] In addition, the sensor piece 18 according to this embodiment includes: a second electrode piece 26 disposed on the second surface 28 side of the insulating sheet 24 and made of conductive cloth; a second joint portion 37 that joints the second surface 28 of the insulating sheet 24 to the inner surface of the second electrode piece 26; and a second protection portion 62 disposed on the outer surface of the second electrode piece 26 to protect the outer surface of the second electrode piece 26.

[0690] According to this embodiment, the second protection portion 62 protects the second electrode piece 26 from external forces, and thus it is possible to suppress a situation where the conduction path of the second electrode piece 26 is damaged. Thereby, it is possible to suppress a situation where the shielding performance of the sensor piece 18 is degraded.

[0691] The first protection portion 61 and the second protection portion 62 according to this embodiment are configured to include a resin material. Thereby, the strength of the first protection portion 61 and the second protection portion 62 is improved. In addition, the operation of disposing the first protection portion 61 on the surface of the first electrode piece 25 can be easily performed, and the operation of disposing the second protection portion 62 on the surface of the second electrode piece 26 can be easily performed.

[0692] The first protection portion 61 according to this embodiment is formed in a layer shape covering the outer surface of the first electrode piece 25. Thereby, the outer surface of the first electrode piece 25 can be reliably covered, and thus the first electrode piece 25 can be further protected. As a result, it is possible to further suppress a situation where the resistance value of the sensor piece 18 changes.

[0693] In addition, the second protection portion 62 is formed in a layer shape covering the outer surface of the second electrode piece 26. Thereby, the outer surface of the second electrode piece 26 can be reliably covered, and thus the second electrode piece 26 can be further protected. As a result, the shielding performance of the sensor piece 18 can be further improved.

[0694] The conductive cloth constituting the first electrode piece 25 according to this embodiment is woven from a plurality of filament aggregates 72. The first protection portion 61 is formed on the outer periphery of the filament aggregate 72. Thereby, the filament aggregate 72 can be protected by the first protection portion 61, and thus it is possible to further suppress a situation where the resistance value of the sensor piece 18 changes.

[0695] The first joint portion 36 according to this embodiment is interposed between the insulating sheet 24 and the first electrode piece 25. Thereby, the insulating sheet 24 and the first electrode piece 25 can be reliably joined.

[0696] The conductive cloth constituting the first electrode piece 25 according to this embodiment is woven from a plurality of filament aggregates 72, and the filament aggregate 72 includes a plurality of filaments 71. The conductive cloth has a first opening portion 34a that opens between the plurality of filament aggregates 72. The opening ratio, which is the ratio of the opening area of the first opening portion 34a to the area of the first electrode piece 25, is 3% or more. Thereby, when an external force is applied to the first electrode piece 25, the first opening portion 34a deforms to absorb the external force. Thereby, it is possible to suppress a situation where an excessive stress is applied to the first electrode piece 25, and thus it is possible to suppress a situation where the conduction path of the first electrode piece 25 is broken. As a result, it is possible to suppress a situation where the resistance value of the sensor piece 18 changes.

[0697] The insulating sheet 24 involved in this method is made of a foamed elastomer. Thereby, the flexibility of the insulating sheet 24 can be improved. As a result, when an external force is applied to the sensor sheet 18, the external force can be absorbed by the deformation of the insulating sheet 24. Thereby, the situation of applying excessive stress to the first electrode sheet 25 can be suppressed, and thus the situation of breakage of the conduction path of the first electrode sheet 25 can be suppressed. As a result, the change in the resistance value of the sensor sheet 18 can be suppressed.

[0698] The conductive cloth involved in this method is woven from a plurality of filament aggregates 72. The filament aggregate 72 includes a plurality of filaments 71 and a plating layer 33 formed on at least a part of the surface of the filaments 71. By bringing the plating layers 33 formed on the surfaces of the plurality of filaments 71 into contact with each other, the plurality of filaments 71 are electrically connected. Thereby, the conduction path of the first electrode sheet 25 is formed.

[0699] The plating layer 33 is formed on the surface of each of the plurality of filaments 71. Thereby, even when an external force is applied to the sensor sheet 18 and the relative positions of the plurality of filaments 71 change, it is easy to form a conduction path through the plating layer 33 formed on the surface of each filament 71. As a result, the change in the resistance value of the sensor sheet 18 can be suppressed.

[0700] (Embodiment 4-2)

[0701] Next, with reference to Figure 70-71 , Embodiment 4-2 will be described. As Fig.70 shown, the first joint portion 36 involved in this method includes a first exposed joint portion 36a exposed on the outer surface of the first electrode sheet 25. The first exposed joint portion 36a is formed in a layer shape on the outer surface of the first electrode sheet 25. The first exposed joint portion 36a also serves as a first protection portion 61 for protecting the first electrode sheet 25. Thereby, compared with the case where the first protection portion 61 is additionally arranged and fixed to the first electrode sheet 25 in addition to the first joint portion 36, the manufacturing process of the sensor sheet 18 can be simplified.

[0702] As Fig.71 shown, the first electrode sheet 25 includes a first opening 34a. The first joint portion 36 penetrates into the inside of the first opening 34a. The portion of the first joint portion 36 that penetrates into the first opening 34a is formed as a first penetrating joint portion 36b. The first penetrating joint portion 36b penetrates through the first electrode sheet 25 and is continuous with the first exposed joint portion 36a. As described above, since the first exposed joint portion 36a also serves as the first protection portion 61, the first penetrating joint portion 36b is continuous with the first protection portion 61.

[0703] According to this method, the first joint portion 36 can penetrate into the first opening 34a of the first electrode piece 25 to form a first penetration joint portion 36b, and the first exposed joint portion 36a and the first penetration joint portion 36b are formed into a continuous shape. Thus, the first joint portion 36 is laminated on the first surface 27 of the insulating sheet 24, and the first electrode piece 25 is disposed on the first joint portion 36. When the first electrode piece 25 is pressed toward the insulating sheet 24, the first penetration joint portion 36b penetrates into the first opening 34a of the first electrode piece 25, and then the first exposed joint portion 36a is formed by covering the first electrode piece 25. The first exposed joint portion 36a can be used as a first protection portion 61 for protecting the first electrode piece 25.

[0704] The opening ratio of the first opening 34a according to this method is 3% or more, so that the first joint portion 36 can easily penetrate into the first opening 34a. Thus, the sensor sheet 18 according to this method can be easily manufactured. It should be noted that the opening ratio of the first opening 34a is preferably 5% or more, more preferably 10% or more, so that the first joint portion 36 can more easily penetrate into the first opening 34a.

[0705] In addition, as Fig.70 shown, the second joint portion 37 according to this method includes a second exposed joint portion 37a exposed on the outer surface of the second electrode piece 26. The second exposed joint portion 37a is formed in a layer shape on the outer surface of the second electrode piece 26. The second exposed joint portion 37a also serves as a second protection portion 62 for protecting the second electrode piece 26. The configurations of the second joint portion 37 and the second electrode piece 26 are the same as those of the first joint portion 36 and the first electrode piece 25, so the repeated description is omitted.

[0706] It should be noted that for the reference numerals used in the drawings after Embodiment 4-2 that are the same as the reference numerals used in the already presented embodiments, unless otherwise specified, they represent the same constituent elements as those in the already presented embodiments.

[0707] (Embodiment 4-3)

[0708] Next, Embodiment 4-3 will be described with reference to Figure 72-73 . As Fig.72 shown, the first electrode piece 25 according to this method is disposed on the first surface 27 of the insulating sheet 24. The first electrode piece 25 may be in contact with the first surface 27 of the insulating sheet 24 over the entire surface or may be in local contact. Thus, by directly contacting the insulating sheet 24 and the first electrode piece 25, a first direct region 38 (see Fig.73 ) is formed where there is no first joint portion 36 between the insulating sheet 24 and the first electrode piece 25.

[0709] The first joint portion 36 is disposed on the outer surface of the first electrode sheet 25. Thus, the portion of the first joint portion 36 exposed on the outer surface of the first electrode sheet 25 is formed as the first exposed joint portion 36c. The first exposed joint portion 36c is formed in a layer shape on the outer surface of the first electrode sheet 25. The first exposed joint portion 36c also serves as the first protection portion 61a for protecting the first electrode sheet 25.

[0710] As Fig.73 shown, the first electrode sheet 25 has a first opening 34a. The first joint portion 36 penetrates into the interior of the first opening 34a. The portion of the first joint portion 36 that penetrates into the first opening 34a is formed as the first penetrating joint portion 36d. The first penetrating joint portion 36d penetrates through the first electrode sheet 25 and is continuous with the first exposed joint portion 36c. As described above, since the first exposed joint portion 36c also serves as the first protection portion 61a, the first penetrating joint portion 36d is continuous with the first protection portion 61a.

[0711] According to this embodiment, the first joint portion 36 can penetrate into the first opening 34a of the first electrode sheet 25 to form the first penetrating joint portion 36d, and the first exposed joint portion 36c and the first penetrating joint portion 36d can be formed in a continuous shape. Thus, the first joint portion 36 is laminated on the first surface 27 of the insulating sheet 24, and the first electrode sheet 25 is disposed on the outer surface of the first joint portion 36. When the first electrode sheet 25 is pressed against the insulating sheet 24, the first penetrating joint portion 36d penetrates into the first opening 34a of the first electrode sheet 25, and then the first exposed joint portion 36c is formed by covering the first electrode sheet 25, and the first exposed joint portion 36c can be used as the first protection portion 61a for protecting the first electrode sheet 25.

[0712] In addition, as Fig.72 shown, the second electrode sheet 26 according to this embodiment is disposed on the second surface 28 of the insulating sheet 24. The second electrode sheet 26 may be in surface-to-surface contact with the second surface 28 of the insulating sheet 24 or may be in partial contact. Thus, the insulating sheet 24 is in direct contact with the second electrode sheet 26, thereby forming a second direct region 39 in which there is no second joint portion 37 between the insulating sheet 24 and the second electrode sheet 26.

[0713] The second joint portion 37 is disposed on the outer surface of the second electrode sheet 26. Thus, the portion of the second joint portion 37 exposed on the outer surface of the second electrode sheet 26 is formed as the second exposed joint portion 37c. The second exposed joint portion 37c is formed in a layer shape on the outer surface of the second electrode sheet 26. The second exposed joint portion 37c also serves as the second protection portion 62a for protecting the second electrode sheet 26. The configurations of the second joint portion 37 and the second electrode sheet 26 are the same as those of the first joint portion 36 and the first electrode sheet 25, so redundant descriptions are omitted.

[0714] The rest is the same as that of Embodiment 4-2, and thus the repeated description is omitted.

[0715] According to this embodiment, the first electrode sheet 25 is placed on the first surface 27 of the insulating sheet 24, and the first joint portion 36 formed in a layered shape is placed on the first electrode sheet 25. Then, the first joint portion 36 is pressed toward the insulating sheet 24. As a result, the first joint portion 36 intrudes into the first opening 34a of the first electrode sheet 25 to form a first intrusion joint portion 36d. The first intrusion joint portion 36d contacts the first surface 27 of the insulating sheet 24 within the first opening 34a. Through the first intrusion joint portion 36d within the first opening 34a, the insulating sheet 24 is joined to the first electrode sheet 25. It should be noted that the functions and effects of the second joint portion 37 and the second electrode sheet 26 are the same as those of the first joint portion 36 and the first electrode sheet 25, and thus the repeated description is omitted.

[0716] (Embodiment 4-4)

[0717] Next, refer to Fig.74 to describe Embodiment 4-4. As Fig.74 shown, the sensor sheet 18 according to this embodiment is different from that of Embodiment 4-1 in that the second electrode sheet 26 is not arranged on the second surface 28 side of the insulating sheet 24. The rest is the same as that of Embodiment 4-1, and thus the repeated description is omitted.

[0718] In addition, although not shown in detail, the sensor sheet 18 according to Embodiment 4-2 and Embodiment 4-3 may also be configured such that the second electrode sheet 26 is not arranged on the second surface 28 side of the insulating sheet 24.

[0719] The present invention is not limited to the above embodiments and can be applied to various embodiments without departing from the gist thereof.

Claims

1. A sensor sheet (18), wherein: The sensor sheet comprises: An insulating sheet (24) having a first surface (27) and a second surface (28), and formed of a foam; A conductive first electrode sheet (25) disposed on the first surface side of the insulating sheet and having a first through opening (34a); a first joining portion (36) for joining the insulating sheet to the first electrode sheet; A conductive second electrode sheet (26) disposed on the second surface side of the insulating sheet and having a penetrating second opening (34b); as well as a second joining portion (37) for joining the insulating sheet to the second electrode sheet, The first electrode sheet and the second electrode sheet are conductive fabrics woven from a plurality of filament assemblies (72). The plurality of filament assemblies include a plurality of filaments (71) and a plating layer (33) formed on at least a portion of the surface of the filaments. The first electrode sheet includes the first opening portion opened between the plurality of filament assemblies. The second electrode sheet includes a second opening portion opened between the plurality of filament assemblies. The sensor sheet is configured so that in a stress-strain curve in a tensile test, there is no yield point showing a maximum value in the range of strain of 0.5 to 10%, The ratio of the opening area of ​​the first opening to the area of ​​the first electrode sheet, that is, the opening ratio, is greater than 1% and less than 50%. The ratio of the opening area of ​​the second opening to the area of ​​the second electrode sheet, that is, the opening ratio, is 1% or more and 50% or less.

2. The sensor sheet according to claim 1, wherein: The sensor sheet is configured such that, in the stress-strain curve, the maximum value of stress when the strain is 0 to 5% is 0.5 MPa or less.

3. The sensor sheet according to claim 1, wherein: The sensor sheet is configured such that, in the stress-strain curve, the maximum value of stress when the strain is 0 to 20% is 3 MPa or less.

4. The sensor sheet according to claim 1, wherein: The first electrode sheet is configured so that, in the stress-strain curve, the maximum value of stress when the strain is 0 to 5% is 5 MPa or less.

5. The sensor sheet according to claim 1, wherein: The first electrode sheet is configured so that, in the stress-strain curve, the maximum value of stress when the strain is 0 to 20% is 10 Pa or less.

6. The sensor sheet according to any one of claims 1 to 5, wherein: The stress-strain curve is a stress-strain curve obtained when a test piece of 20 mm×90 mm is held and a tensile test is performed at a tensile speed of 1 mm / s.

7. The sensor sheet according to any one of claims 1 to 5, wherein: The cross section of the filament is non-circular.

8. The sensor sheet according to claim 7, wherein: The cross section of the filament is polygonal.

9. The sensor sheet according to any one of claims 1 to 5, wherein: The filament assembly further includes an internal space (80) formed in at least a portion between adjacent filaments.

10. The sensor sheet according to claim 9, wherein The filament assembly includes the plurality of filaments arranged in a plane direction of a sheet surface of the first electrode sheet and in a normal direction of the sheet surface.

11. The sensor sheet according to claim 10, wherein: The internal space is formed in at least a portion between the filaments adjacent to each other in the plane direction and in at least a portion between the filaments adjacent to each other in the normal direction.

12. The sensor sheet according to claim 9, wherein: The plating layer is formed on at least a portion of the surface of the filament that is exposed to the internal space, The surface of the filament is exposed at a portion of the surface of the filament that is exposed to the internal space and at a portion where the plating layer is not formed.

13. The sensor sheet according to any one of claims 1 to 5, wherein: The plurality of filament assemblies include a warp filament assembly and a weft filament assembly, The plating layer is formed on at least a portion of a non-exposed portion (81) where the warp filament assembly and the weft filament assembly face each other and cross each other.

14. The sensor sheet according to any one of claims 1 to 3, wherein: The plating layer is formed on at least a portion of the surface of the filament exposed on the outer surface of the filament assembly, In a portion of the surface of the filaments exposed on the outer surface of the filament assembly where the plating layer is not formed, the surface of the filaments is exposed.

15. The sensor sheet according to any one of claims 1 to 5, wherein: The plurality of filament assemblies include a warp filament assembly (72a) and a weft filament assembly (72b), In the portion where the warp filament assembly and the weft filament assembly intersect each other, the coating is formed on at least a portion of the portion where the filaments exposed on the outer surface of the warp filament assembly and the filaments exposed on the outer surface of the weft filament assembly are opposite to each other, and in the portion where the coating is not formed, the outer surface of the filament is exposed.

16. The sensor sheet according to any one of claims 1 to 5, wherein: The plating layer is a single layer composed of nickel, or a multilayer including a layer composed of copper and a layer composed of nickel.

17. The sensor sheet according to any one of claims 1 to 5, wherein: The sensor sheet further includes a bonding portion (36) that bonds the first surface of the insulating sheet to the inner surface of the first electrode sheet.

18. The sensor sheet according to claim 17, wherein: The sensor sheet further includes a protection portion (60) which is disposed on an outer surface of the first electrode sheet and protects the outer surface of the first electrode sheet.

19. The sensor sheet according to claim 17, wherein: The joint portion is interposed between the insulating sheet and the first electrode sheet.

20. The sensor sheet according to claim 17, wherein: The bonding portion includes an exposed bonding portion (36a) exposed on the outer surface of the first electrode sheet, The exposed joint portion is disposed on the outer surface of the first electrode sheet and also serves as a protection portion for protecting the outer surface of the first electrode sheet.

21. The sensor sheet according to claim 17, wherein: By making the insulating sheet directly contact the first electrode sheet, a direct region (38) without the junction being interposed exists between the insulating sheet and the first electrode sheet.

22. The sensor sheet according to claim 17, wherein: The joint portion is interposed between the insulating sheet and the first electrode sheet.

23. The sensor sheet according to any one of claims 1 to 5, wherein: The plurality of filament assemblies include a warp filament assembly and a weft filament assembly, An area of ​​a portion where the warp filament assembly and the weft filament assembly intersect each other is larger than an opening area of ​​the first opening in a state where no strain is generated in the first electrode sheet.

24. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet has an extension portion (31) extending from a long side edge of the first electrode sheet along the longitudinal direction in an extension direction. In the extension portion, an occupied area of ​​the plurality of warp filament assemblies when projected in the thickness direction of the extension portion is larger than an occupied area of ​​the plurality of weft filament assemblies when projected in the thickness direction of the extension portion.

25. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet includes an extension portion extending from a long side edge of the first electrode sheet along the longitudinal direction in an extension direction. In the extended portion, an angle α formed between the extended direction of the extended portion and the length direction of the warp filament assembly is smaller than an angle β formed between the extended direction of the extended portion and the length direction of the weft filament assembly.

26. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet includes an extension portion extending from a long side edge of the first electrode sheet along the longitudinal direction in an extension direction. In the extended portion, an angle α formed between the extended direction of the extended portion and the length direction of the warp filament assembly is greater than an angle β formed between the extended direction of the extended portion and the length direction of the weft filament assembly.

27. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet includes an extension portion extending from a long side edge of the first electrode sheet along the longitudinal direction in an extension direction. In the extended portion, the interval between adjacent filaments among the plurality of filaments constituting the weft filament assembly is smaller than the interval between adjacent filaments among the plurality of filaments constituting the warp filament assembly.

28. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet has a narrow width portion (35) whose width in a direction intersecting the longitudinal direction of the first electrode sheet is narrower than that of other portions. In the narrow width portion, an occupied area of ​​the plurality of warp filament assemblies when projected in the thickness direction of the narrow width portion is larger than an occupied area of ​​the plurality of weft filament assemblies when projected in the thickness direction of the narrow width portion.

29. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet has a narrow width portion, the width of which in a direction intersecting the longitudinal direction of the first electrode sheet is narrower than that of other portions. In the narrow width portion, the interval between adjacent filaments among the plurality of filaments constituting the weft filament assembly is smaller than the interval between adjacent filaments among the plurality of filaments constituting the warp filament assembly.

30. The sensor sheet according to claim 23, wherein: The first electrode sheet is formed into a long strip along the length direction. The first electrode sheet has a narrow width portion, the width of which in a direction intersecting the longitudinal direction of the first electrode sheet is narrower than that of other portions. The number of the plurality of filaments constituting the warp filament assembly in the narrow width portion is greater than the number of the plurality of filaments constituting the warp filament assembly in a portion different from the narrow width portion.

31. A method for manufacturing a sensor sheet, wherein: The manufacturing method of the sensor sheet comprises: A step of forming a filament aggregate by gathering a plurality of filaments; A step of forming a base fabric by weaving a plurality of the filament assemblies; a step of forming a conductive cloth by plating the base cloth; and The step of forming the sensor sheet by bonding the conductive cloth to the first surface of an insulating sheet made of an elastic material having a first surface and a second surface.

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