Linear pressure sensor

Abstract

To provide a linear pressure sensor that can suppress the occurrence of plastic strain in the conductive member. [Solution] The linear pressure sensor 1 comprises a first conductive member 2 and a second conductive member 3 arranged opposite each other with a gap between them, and a non-conductive spacing member 4 that maintains the distance between the first conductive member 2 and the second conductive member 3. The first conductive member 2 and the second conductive member 3 come into contact due to elastic deformation caused by external pressure. The first conductive member 2 has a first conductive elastic body 21 that is conductive and elastic, and a first conductive wire 22 integrated with the first conductive elastic body 21. The second conductive member 3 has a second conductive elastic body 31 that is conductive and elastic, and a second conductive wire 32 integrated with the second conductive elastic body 31. At least one of the first conductive wire 22 and the second conductive wire 32 is made of conductive fibers, and in cross-sectional view, the spacing member 4 is formed in a cylindrical shape.

Description

Technical Field

[0001] The present invention relates to a linear pressure sensor.

Background Art

[0002] Conventionally, for example, in an opening / closing member such as a sliding door of an automobile, a sensor for detecting entrapment of a human body or the like is attached to the forward end in the moving direction when closing the opening (see, for example, Patent Documents 1 and 2).

[0003] The pressure sensor described in Patent Document 1 has a circular structure in which four electrode wires are arranged spirally on the inner peripheral surface of a circular hollow cylindrical elastic insulator having a predetermined length so as not to contact each other. Each electrode wire is coated with a conductive rubber containing carbon black on the surface of an electric conductor made of a tinned soft copper stranded wire.

[0004] When manufacturing this pressure sensor, a large-diameter spacer and a small-diameter spacer in which a conductor as a tension member is coated with resin are prepared, and a stranded wire is made by arranging four electrode wires spirally around the large-diameter spacer together with four small-diameter spacers. Then, an elastic insulator is extrusion-molded on the outer periphery of this stranded wire, and the large-diameter spacer and the small-diameter spacer are pulled out.

[0005] The foreign object detection sensor described in Patent Document 2 includes an elastically deformable outer skin formed in a long and cylindrical shape by an insulating elastomer, and a first electrode portion and a second electrode portion disposed inside the outer skin and extending in parallel with a predetermined space therebetween. The first electrode portion has a first conductive member having conductivity and elasticity, and a first core wire embedded inside the first conductive member. Similarly, the second electrode portion has a second conductive member having conductivity and elasticity, and a second core wire embedded inside the second conductive member. The first core wire is a single wire made of copper or the like. The second core wire is formed of a string-like core material having elasticity such as rubber, a plurality of conductive wires spirally wound around the core material, and conductive fibers covering the core material and the conductive wires.

[0006] When manufacturing this foreign object detection sensor, the first and second electrode portions are formed by extruding conductive elastomer onto the outer circumference of the first and second core wires, respectively, and the outer sheath is formed by extruding insulating elastomer around the first and second electrode portions. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 10-281906 [Patent Document 2] Japanese Patent Publication No. 2019-145466 [Overview of the project] [Problems that the invention aims to solve]

[0008] In sensors configured as described above (pressure sensor in Patent Document 1, foreign object detection sensor in Patent Document 2), if subjected to a large external pressure, the metal conductor wire (electrical conductor in Patent Document 1, conductor in Patent Document 2) may undergo plastic deformation, causing plastic strain in the conductive member (electrode wire in Patent Document 1, second electrode part in Patent Document 2), potentially altering the sensitivity. Furthermore, if this plastic strain is large, the conductive members may remain in contact with each other. Here, plastic strain refers to permanent deformation in which a part of the conductive member bends due to pressure and does not completely return to its original shape even after the pressure is removed.

[0009] Furthermore, in the pressure sensor described in Patent Document 1, four electrode wires and a small-diameter spacer are arranged spirally around a large-diameter spacer, and the process of pulling out the large-diameter and small-diameter spacers after forming the elastic insulator is time-consuming, increasing manufacturing costs. On the other hand, the foreign object detection sensor described in Patent Document 2 can reduce manufacturing costs compared to the pressure sensor described in Patent Document 1, but since the first electrode section and the second electrode section are arranged in a straight line parallel to each other, there is a problem that, for example, if pressure is applied in a direction perpendicular to the alignment direction of the first electrode section and the second electrode section, it cannot be detected, thus limiting the direction of detectable pressure.

[0010] The object of the present invention is to provide a linear pressure sensor capable of suppressing the occurrence of plastic strain in the conductive member. Another object of the present invention is to provide a linear pressure sensor that can suppress manufacturing costs while ensuring a wide range of detectable pressure directions. [Means for solving the problem]

[0011] To achieve the above objective, the present invention provides a linear pressure sensor comprising a first conductive member and a second conductive member arranged opposite each other with a gap between them, and a non-conductive gap-holding member that maintains the gap between the first conductive member and the second conductive member, wherein the first conductive member and the second conductive member come into contact by elastic deformation due to external pressure, wherein the first conductive member comprises a first conductive elastic body having conductivity and elasticity and a first conductive wire integrated with the first conductive elastic body, the second conductive member comprises a second conductive elastic body having conductivity and elasticity and a second conductive wire integrated with the second conductive elastic body, at least one of the first conductive wire and the second conductive wire is made of conductive fibers, and in cross-sectional view, the gap-holding member is formed in a cylindrical shape. [Effects of the Invention]

[0012] According to the present invention, it is possible to suppress the occurrence of plastic strain in the conductive member and stabilize the sensitivity of the pressure sensor. Furthermore, according to the present invention, it is possible to suppress manufacturing costs while ensuring a wide range of detectable pressure directions. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing a linear pressure sensor according to an embodiment of the present invention. [Figure 2] (a) and (b) are cross-sectional views showing the first and second conductive wires of the linear pressure sensor. [Figure 3] This is a perspective view showing the configuration of a pressure-sensitive sensor. [Figure 4A] Cross-sectional view showing a linear pressure-sensitive sensor according to the first modification example. [Figure 4B] Cross-sectional view showing a linear pressure-sensitive sensor according to the second modification example. [Figure 4C] Cross-sectional view showing a linear pressure-sensitive sensor according to the third modification example. [Figure 4D] Cross-sectional view showing a linear pressure-sensitive sensor according to the fourth modification example. [Figure 4E] Cross-sectional view showing a linear pressure-sensitive sensor according to the fifth modification example. [Figure 4F] Cross-sectional view showing a linear pressure-sensitive sensor according to the sixth modification example. [Figure 4G] Cross-sectional view showing a linear pressure-sensitive sensor according to the seventh modification example. [Figure 4H] Cross-sectional view showing a linear pressure-sensitive sensor according to the eighth modification example. [Figure 5A] Cross-sectional view showing a linear pressure-sensitive sensor according to the ninth modification example. [Figure 5B] Cross-sectional view showing a linear pressure-sensitive sensor according to the tenth modification example. [Figure 5C] Cross-sectional view showing a linear pressure-sensitive sensor according to the eleventh modification example. [Figure 5D] Cross-sectional view showing a linear pressure-sensitive sensor according to the twelfth modification example. [Figure 5E] Cross-sectional view showing a linear pressure-sensitive sensor according to the thirteenth modification example. [Figure 5F] Cross-sectional view showing a linear pressure-sensitive sensor according to the fourteenth modification example. [Figure 5G] Cross-sectional view showing a linear pressure-sensitive sensor according to the fifteenth modification example. [Figure 5H] Cross-sectional view showing a linear pressure-sensitive sensor according to the sixteenth modification example. [Figure 5I] Cross-sectional view showing a linear pressure-sensitive sensor according to the seventeenth modification example. [Figure 6] (a) and (b) are cross-sectional views showing modification examples of the first and second conductive wires. [Figure 7](a) and (b) are cross-sectional views showing modified examples of the first and second conductive wires. [Figure 8] (a) and (b) are cross-sectional views showing modified examples in which multiple conductive fibers are woven together to form a first conductive wire and a second conductive wire in a strip shape. [Figure 9] This is a cross-sectional view of a linear pressure sensor including a first conductive elastic body and a second conductive elastic body, each embedded with a first conductive wire and a second conductive wire, both configured in a strip shape. [Modes for carrying out the invention]

[0014] [Embodiment] Figure 1 is a cross-sectional view showing a linear pressure sensor according to an embodiment of the present invention. Figures 2(a) and (b) are cross-sectional views showing the first and second conductive wires of the linear pressure sensor. Figure 3 is a perspective view showing the configuration of the linear pressure sensor.

[0015] The linear pressure sensor 1 is used to detect contact with a human body or other object while the opening / closing member is moving, for example, on an opening / closing member such as a car's sliding door. When contact is detected, the control device stops the movement of the opening / closing member or reverses the direction of movement of the opening / closing member to prevent pinching. The linear pressure sensor 1 is attached to the forward end of the direction of movement of the opening / closing member when closing an opening (for example, a car's entrance / exit door), and outputs a signal to the control device indicating that pressure is applied due to contact with a human body or other object.

[0016] As shown in Figure 1, the linear pressure sensor 1 comprises a first conductive member 2 and a second conductive member 3 arranged opposite each other with a gap between them, a non-conductive gap-holding member 4 that maintains the distance between the first conductive member 2 and the second conductive member 3, and an outer sheath 5 that houses these components. When the first conductive member 2 and the second conductive member 3 come into contact due to elastic deformation caused by external pressure, the state of the signal output to the control device changes.

[0017] The first conductive member 2 comprises a first conductive elastic body 21 having conductivity and elasticity, and a first conductive wire 22 integrated with the first conductive elastic body 21. The second conductive member 3 comprises a second conductive elastic body 31 having conductivity and elasticity, and a second conductive wire 32 integrated with the second conductive elastic body 31. The first conductive elastic body 21 and the second conductive elastic body 31 are made of, for example, a conductive elastomer compounded with carbon black.

[0018] The first conductive member 2 is formed in a hollow tubular shape. The second conductive member 3 is formed in a solid axial shape and is coaxially arranged inside the first conductive member 2. The spacing member 4 is made of an insulating elastomer and is arranged between the first conductive member 2 and the second conductive member 3. The outer sheath 5 is made of an insulating elastomer and covers the outer circumference of the first conductive elastic body 21.

[0019] The first conductive wire 22 and the second conductive wire 32 are made of conductive fibers. Specifically, as shown in Figures 2(a) and (b) and Figure 3, the first conductive wire 22 is made by twisting together a plurality of conductive fibers 220, and the second conductive wire 32 is made by twisting together a plurality of conductive fibers 320. The conductive fibers 220 of the first conductive wire 22 have a core material 221 made of synthetic fibers such as nylon, and a metal plating layer 222 made of a highly conductive metal such as copper, silver, or tin is formed to cover this core material 221. Similarly, the conductive fibers 320 of the second conductive wire 32 also have a core material 321 made of synthetic fibers such as nylon, and a metal plating layer 322 made of a highly conductive metal such as copper is formed to cover the core material 321. In other words, conductivity is imparted to the conductive fibers 220 and 320 by plating a conductive metal on the surface of the non-conductive fibers. In this embodiment, the conductive fibers 220 and 320 have a circular cross-section.

[0020] The first conductive wire 22 is embedded in one location in the circumferential direction of the first conductive elastic body 21 and is integrated with the first conductive elastic body 21. The metal plating layer 222 of the conductive fiber 220 is in contact with the first conductive elastic body 21. The conductivity per unit area of ​​the first conductive wire 22 in a cross section perpendicular to the longitudinal direction of the linear pressure sensor 1 is higher than the conductivity per unit area of ​​the first conductive elastic body 21 in the same cross section, and the electrical resistance of the first conductive member 2 is reduced by the first conductive wire 22. The first conductive wire 22 may be embedded in multiple locations in the circumferential direction of the first conductive elastic body 21.

[0021] The second conductive wire 32 is embedded in the center of the second conductive elastic body 31 and is integrated with the second conductive elastic body 31. The metal plating layer 322 of the conductive fiber 320 is in contact with the second conductive elastic body 31. The conductivity per unit area of ​​the second conductive wire 32 in a cross section perpendicular to the longitudinal direction of the linear pressure sensor 1 is higher than the conductivity per unit area of ​​the second conductive elastic body 31 in the same cross section, and the electrical resistance of the second conductive member 3 is reduced by the second conductive wire 32.

[0022] The first conductive wire 22 and the second conductive wire 32 extend from the first conductive elastic body 21 and the second conductive elastic body 31, respectively, at their longitudinal ends, and these extended portions are connected to a signal line between the control device and the control device. The control device has a voltage source and applies the output voltage of this voltage source between the first conductive wire 22 and the second conductive wire 32. When the first conductive elastic body 21 and the second conductive elastic body 31 are not in contact, the voltage between the first conductive wire 22 and the second conductive wire 32 is the same as the output voltage of the voltage source. When the first conductive elastic body 21 and the second conductive elastic body 31 come into contact, the voltage between the first conductive wire 22 and the second conductive wire 32 decreases. The control device can detect that pressure has been applied to the linear pressure sensor 1 by this change in voltage.

[0023] In this embodiment, three circular cross-sectional spacing members 4 are arranged at equal intervals (every 120°) along the circumferential direction of the first conductive elastic body 21 between the inner circumferential surface 21a of the first conductive elastic body 21 and the outer circumferential surface 31a of the second conductive elastic body 31. That is, the three spacing members 4 are arranged such that two spacing members 4 do not align with the second conductive member 3 in the diametrical direction of the first conductive elastic body 21. As a result, no matter which direction the first conductive elastic body 21 is pressed from, the second conductive member 3 will not be caught between two spacing members 4, and the first conductive member 2 and the second conductive member 3 will come into contact.

[0024] Each of the three spacing members 4 has a portion of its outer circumferential surface 4a joined to the inner circumferential surface 21a of the first conductive elastic body 21, and another portion of its outer circumferential surface 4a joined to the outer circumferential surface 31a of the second conductive elastic body 31, thereby fixing its position in the annular space between the first conductive elastic body 21 and the second conductive elastic body 31.

[0025] As shown in Figure 3, the three spacing members 4, the first conductive wire 22, and the second conductive wire 32 extend parallel to the first conductive member 2 and the second conductive member 3 without being tilted with respect to the central axis direction of the first conductive member 2. In other words, if the linear pressure sensor 1 is supported in a straight line, the first conductive elastic body 21, the first conductive wire 22, the second conductive elastic body 31, the second conductive wire 32, and the three spacing members 4 extend in a straight line along the longitudinal direction of the linear pressure sensor 1.

[0026] Furthermore, multiple spacing members 4 may be arranged spirally between the first conductive elastic body 21 and the second conductive elastic body 31. However, if the multiple spacing members 4 are arranged linearly parallel to the second conductive member 3, the manufacturing process can be simplified, and thus costs can be reduced.

[0027] (Operation and Effects of the Embodiment) As described above, according to this embodiment, the first conductive wire 22 and the second conductive wire 32 are made of multiple conductive fibers 220, 320 and are flexible and easily bent. Therefore, compared to the case where a metal conductor wire made by twisting together multiple metal strands of copper alloy or aluminum alloy with the same diameter as the conductive fibers 220, 320 is embedded in the first conductive elastic body 21 and the second conductive elastic body 31, it is possible to suppress the occurrence of plastic strain in the first conductive member 2 and the second conductive member 3. Furthermore, compared to the case where a metal conductor wire made by twisting together metal strands with the same cross-sectional area as the metal plating layers 222, 322 of the conductive fibers 220, 320 but with a smaller diameter is embedded in the first conductive elastic body 21 and the second conductive elastic body 31, a wider contact area with the first conductive elastic body 21 and the second conductive elastic body 31 can be secured, thus reducing the contact resistance with the first conductive elastic body 21 and the second conductive elastic body 31.

[0028] Furthermore, according to this embodiment, there is no need to arrange multiple electrode wires in a spiral shape, as in the pressure sensor described in Patent Document 1, for example, which reduces manufacturing costs. In addition, since the first conductive member 2 and the second conductive member 3 come into contact regardless of the direction from which the linear pressure sensor 1 receives pressure, a wide range of detectable pressure directions can be ensured.

[0029] [Modified examples of the spacing member 4 and outer shell 5] Figures 4A-4H and 5A-5I are cross-sectional views showing modified linear pressure sensors 1A-1Q in which the shape and arrangement of the spacing member 4 and the outer sheath 5 have been altered. Figures 4A-4H and 5A-5I show the linear pressure sensors 1A-1Q in a cross-section perpendicular to the longitudinal direction. In these modified examples, the spacing member 4 extends parallel to the first conductive member 2 and the second conductive member 3 without being tilted with respect to the central axis direction of the first conductive member 2, similar to the embodiment described above. In the modified example shown in Figures 4A-4H, the second conductive member 3 is supported by three spacing members 4 arranged at equal intervals along the circumferential direction of the first conductive elastic body 21. In the modified example shown in Figures 5A-5I, the second conductive member 3 is supported by one spacing member 4.

[0030] In the first modified linear pressure sensor 1A shown in Figure 4A, each of the three spacing members 4 is formed in a rectangular cross-section. In the second modified linear pressure sensor 1B shown in Figure 4B, the central part of each of the three spacing members 4 in the radial direction of the first conductive member 2 is narrowly constricted. In the third modified linear pressure sensor 1C shown in Figure 4C, each of the three spacing members 4 is formed in an arc-shaped cross-section. In the fourth modified linear pressure sensor 1D shown in Figure 4D, each of the three spacing members 4 is formed in a cylindrical shape. In the second to fourth modified linear pressure sensors 1B to 1D, the spacing members 4 are more flexibly elastically deformable than in the first modified linear pressure sensor 1A.

[0031] The linear pressure sensor 1E according to the fifth modified example shown in Figure 4E, and the linear pressure sensor 1F according to the sixth modified example shown in Figure 4F, both have a circular cross-section for each of the three spacing members 4, similar to the embodiments described above. However, the diameter of the spacing member 4 is larger than the distance between the inner circumferential surface 21a of the first conductive elastic body 21 and the outer circumferential surface 31a of the second conductive elastic body 31. In the linear pressure sensor 1E according to the fifth modified example, a portion of the circumferential spacing member 4 bites into the second conductive elastic body 31, and in the linear pressure sensor 1F according to the sixth modified example, the second conductive elastic body 31 bites into a portion of the circumferential spacing member 4. As a result, the strength of the joint between the spacing member 4 and the second conductive elastic body 31 is increased in the linear pressure sensors 1E and 1F according to the fifth and sixth modified examples.

[0032] In the seventh modified example shown in Figure 4G, the linear pressure sensor 1G has the outer diameter ends of three spacing members 4 in the radial direction of the first conductive member 2 in contact with the outer sheath 5, and the first conductive elastic body 21 is divided into three parts by the three spacing members 4. A first conductive wire 22 is embedded in each of the three divided pieces 211 to 213. These first conductive wires 22 extend from each divided piece 211 to 213 at the longitudinal end of the linear pressure sensor 1G, are bundled together, and connected to a signal line between the linear pressure sensor 1G and the control device.

[0033] The linear pressure sensor 1H according to the eighth modified example shown in Figure 4H has three spacing members 4, each formed in a cylindrical shape, and its outer diameter is larger than the distance between the inner circumferential surface 21a of the first conductive elastic body 21 and the outer circumferential surface 31a of the second conductive elastic body 31. A portion of each spacing member 4 in the circumferential direction bites into the second conductive elastic body 31. In addition, a portion of the outer circumference of the outer sheath 5 is a flat mounting surface 5a. The linear pressure sensor 1H is attached to the object to be mounted, for example, by double-sided tape attached to the mounting surface 5a. The first conductive wire 22 is positioned between the second conductive member 3 and the mounting surface 5a. This position is such that the linear pressure sensor 1H will not deform significantly even when subjected to external pressure.

[0034] The linear pressure sensors 1I to 1P according to the 9th to 16th modified examples shown in Figures 5A to 5H are modified versions of the linear pressure sensors 1A to 1H according to the 1st to 8th modified examples shown in Figures 4A to 4H, in which two of the three spacing members 4 are omitted, leaving only one. Compared to the linear pressure sensors 1A to 1H according to the 1st to 8th modified examples, the linear pressure sensors 1I to 1P according to the 9th to 16th modified examples have lower support rigidity of the second conductive member 3 relative to the first conductive member 2. On the other hand, the first conductive member 2 and the spacing members 4 are more flexibly elastically deformable, and the first conductive member 2 and the second conductive member 3 come into contact with relatively small pressure.

[0035] Furthermore, in the linear pressure sensor 1Q according to the 17th modified example shown in Figure 5I, the second conductive elastic body 31 is formed in an elliptical cross-section, and this second conductive elastic body 31 is supported by a single cylindrical spacing member 4. The spacing member 4 bites into the portion of the outer circumferential surface 31a of the second conductive elastic body 31 that has a small curvature. In this linear pressure sensor 1Q, the gap between the outer circumferential surface 31a of the elliptical second conductive elastic body 31 at both ends in the longitudinal direction and the inner circumferential surface 21a of the first conductive elastic body 21 is narrow, making it easier for the first conductive member 2 and the second conductive member 3 to come into contact.

[0036] [Modified examples of the first conductive wire 22 and the second conductive wire 32] Figures 6(a) and (b) are cross-sectional views showing modified examples of the first conductive wire 22 and the second conductive wire 32. In the above embodiment, the first conductive wire 22 and the second conductive wire 32 were constructed by twisting together conductive fibers 220 and 320 with a circular cross-section. However, in the examples shown in Figures 6(a) and (b), the conductive fibers 220 and 320 have an elliptical cross-section. The conductive fiber 220 of the first conductive wire 22 has a core material 221 made of synthetic fibers with an elliptical cross-section, which is covered with a metal plating layer 222. The conductive fiber 320 of the second conductive wire 32 has a core material 321 made of synthetic fibers with an elliptical cross-section, which is covered with a metal plating layer 322.

[0037] In the examples shown in Figures 6(a) and (b), the first conductive wire 22 consists of seven conductive fibers 220, and the second conductive wire 32 consists of seven conductive fibers 320. The seven conductive fibers 220 constituting the first conductive wire 22 have their short axis and long axis directions aligned in the same direction. Similarly, the seven conductive fibers 320 constituting the second conductive wire 32 have their short axis and long axis directions aligned in the same direction.

[0038] As shown in Figures 6(a) and (b), the first conductive wire 22 and the second conductive wire 32 are designed to deform flexibly when pressure is applied in the direction of the short axis of the conductive fibers 220 and 320, making plastic deformation less likely. Therefore, by arranging the first conductive wire 22 and the second conductive wire 32 so that the direction of movement of the opening / closing member coincides with the direction of the short axis of the conductive fibers 220 and 320, it is possible to prevent the first conductive wire 22 and the second conductive wire 32 from undergoing plastic deformation even when subjected to pressure.

[0039] Figures 7(a) and (b) are cross-sectional views showing further modifications of the first conductive wire 22 and the second conductive wire 32. In these modifications, the conductive fibers 220 and 320 have an elliptical cross-sectional shape with cavities 221a and 321a formed in the center of the core materials 221 and 321. According to these modifications, the elasticity of the first conductive wire 22 and the second conductive wire 32 is increased when pressed in the radial direction perpendicular to the longitudinal direction, making them more flexible and easier to deform.

[0040] Figures 8(a) and (b) are cross-sectional views showing a modified example in which a plurality of conductive fibers 220, 320 are braided together to form a first conductive wire 22 and a second conductive wire 32 in a strip shape. Figure 9 is a cross-sectional view of a linear pressure sensor 11 having a first conductive elastic body 21 and a second conductive elastic body 31 in which the strip-shaped first conductive wire 22 and second conductive wire 32 are embedded.

[0041] The first conductive wire 22 shown in Figure 8(a) is constructed by weaving together multiple conductive fibers 220 extending in the longitudinal direction (left-right direction in the drawing) and multiple conductive fibers 220 extending in the short direction (up-down direction in the drawing) in a grid pattern, with square-shaped spaces 22a formed between these conductive fibers 220. Similarly, the second conductive wire 32 shown in Figure 8(b) is constructed by weaving together multiple conductive fibers 320 extending in the longitudinal direction (left-right direction in the drawing) and multiple conductive fibers 320 extending in the short direction (up-down direction in the drawing) in a grid pattern, with square-shaped spaces 32a formed between these conductive fibers 320.

[0042] The spaces 22a and 32a between the first conductive wire 22 and the second conductive wire 32 may be large enough to accommodate the conductive elastomer, which is the material of the first conductive elastic body 21 and the second conductive elastic body 31, or they may not be large enough to accommodate it. If the conductive elastomer is present in the spaces 22a and 32a, the contact area between the multiple conductive fibers 220 and 320 and the conductive elastomer increases, reducing the electrical resistance. If the conductive elastomer is not present in the spaces 22a and 32a, the first conductive wire 22 and the second conductive wire 32 become more likely to slide relative to the first conductive elastic body 21 and the second conductive elastic body 31 when pressure is applied, increasing the flexibility of the first conductive member 2 and the second conductive member 3.

[0043] The first conductive wire 22 and the second conductive wire 32 may be embedded in the first conductive elastic body 21 and the second conductive elastic body 31 so that their short sides are straight, as shown in Figure 9, but they may also be curved so that their short sides follow the inner circumferential surface 21a of the first conductive elastic body 21 or the outer circumferential surface 31a of the second conductive elastic body 31. Furthermore, the conductive fibers 220 and 320 of the first conductive wire 22 and the second conductive wire 32 may have a circular cross-section as shown in Figures 2(a) and (b), or an elliptical cross-section as shown in Figures 6(a) and (b) or Figures 7(a) and (b).

[0044] As shown in Figures 8(a) and (b), the first conductive wire 22 and the second conductive wire 32 can be formed thinly. By arranging the linear pressure sensor 11 so that pressure is applied perpendicular to the multiple conductive fibers 220 extending in the longitudinal and transverse directions, it is possible to suppress the occurrence of plastic strain in the first conductive member 2 and the second conductive member 3.

[0045] The first conductive wire 22 and the second conductive wire 32 may be made by braiding together non-conductive fibers plated with a conductive metal, or by braiding together non-conductive fibers and then plating them with a conductive metal. In addition, in the examples shown in Figures 8(a) and (b), multiple conductive fibers 220 and 320 are braided together in a grid pattern, but the invention is not limited to this, and for example, multiple conductive fibers 220 and 320 may be braided together in a honeycomb pattern (hexagonal shape). Braiding the conductive fibers 220 and 320 in a honeycomb pattern can increase the longitudinal elasticity of the first conductive wire 22 and the second conductive wire 32.

[0046] [Other variations] In the above embodiment, the case in which the first conductive wire 22 consists of a plurality of conductive fibers 220 and the second conductive wire 32 consists of a plurality of conductive fibers 320 was described, but the invention is not limited to this, and either the first conductive wire 22 or the second conductive wire 32 may be made of a metal conductor wire. In this case, it is desirable to make the one of the first conductive wire 22 and the second conductive wire 32 with the smaller expected maximum deformation amount out of a metal conductor wire. For example, in the case of the linear pressure sensor 1H according to the eighth modified example shown in Figure 4H and the linear pressure sensor 1P according to the sixteenth modified example shown in Figure 5H, it is desirable to make the first conductive wire 22 out of a metal conductor wire. In other words, it is sufficient that at least one of the first conductive wire 22 and the second conductive wire 32 is made of conductive fibers. Also, as shown in Figures 8(a) and (b), when a plurality of conductive fibers are braided together, it is sufficient that at least one of the first conductive wire 22 and the second conductive wire 32 is made out of braided conductive fibers.

[0047] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0048] [1] A linear pressure sensor (1,1A~1Q,11) comprising a first conductive member (2) and a second conductive member (3) arranged opposite each other with a gap between them, and a non-conductive gap-holding member (4) that maintains the gap between the first conductive member (2) and the second conductive member (3), wherein the first conductive member (2) is a first conductive member having conductivity and elasticity A linear pressure sensor (1,1A~1Q,11) comprising an elastic body (21) and a first conductive wire (22) integrated with the first conductive elastic body (21), the second conductive member (3) comprising a second conductive elastic body (31) having conductivity and elasticity and a second conductive wire (32) integrated with the second conductive elastic body (31), and at least one of the first conductive wire (22) and the second conductive wire (32) being made of conductive fibers (220,320).

[0049] [2] The linear pressure sensor (1,1A~1Q,11) described in [1] above, wherein the first conductive member (2) is formed in a hollow tubular shape, and the second conductive member (3) is arranged inside the first conductive member (2).

[0050] [3] The spacing member (4) extends between the first conductive member (2) and the second conductive member (3) in the linear pressure sensor (1,1A~1Q,11) described in [2] above.

[0051] [4] A linear pressure sensor (1,1A~1Q,11) according to any one of [1] to [3] above, wherein the conductive fibers (220,320) are imparted with conductivity by plating a conductive metal on the surface of non-conductive fibers.

[0052] [5] A linear pressure sensor (11) according to any one of [1] to [4] above, comprising conductive fibers (220, 320) in which at least one of the first conductive wire (22) and the second conductive wire (32) is braided together.

[0053] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. Moreover, parts of the above embodiments and each of their variations may be combined as appropriate. [Explanation of Symbols]

[0054] 1,1A~1Q,11…Linear pressure sensor 2…First conductive member 21...First conductive elastic body 22...First conductive wire 220...Conductive fiber 3...Second conductive member 31...Second conductive elastic body 32...Second conductive wire 320...Conductive fiber 4...Spacing member 5…Outer skin

Claims

1. A linear pressure sensor comprising a first conductive member and a second conductive member arranged opposite each other with a gap between them, and a non-conductive gap-holding member that maintains the gap between the first conductive member and the second conductive member, wherein the first conductive member and the second conductive member come into contact due to elastic deformation caused by external pressure, The first conductive member comprises a first conductive elastic body having conductivity and elasticity, and a first conductive wire integrated with the first conductive elastic body. The second conductive member comprises a second conductive elastic body having conductivity and elasticity, and a second conductive wire integrated with the second conductive elastic body. At least one of the first conductive wire and the second conductive wire is made of conductive fiber, In a cross-sectional view, the spacing member is formed in a cylindrical shape. Linear pressure sensor.

2. In a cross-sectional view, the second conductive member is formed in an elliptical shape. The spacing member is positioned to bite into the portion of the outer surface of the second conductive member where the curvature is small. The linear pressure sensor according to claim 1.

3. The first conductive member is formed in a hollow tubular shape, The second conductive member is located inside the first conductive member. A linear pressure sensor according to claim 1 or 2.

4. The spacing member extends between the first conductive member and the second conductive member, parallel to the first conductive member and the second conductive member. The linear pressure sensor according to claim 3.

5. The conductive fibers are imparted with conductivity by plating a conductive metal onto the surface of non-conductive fibers. A linear pressure sensor according to any one of claims 1 to 4.

6. At least one of the first conductive wire and the second conductive wire is made of braided conductive fibers. A linear pressure sensor according to any one of claims 1 to 5.

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