Load Sensor

Abstract

A load sensor (1) comprises: a resilient plate-shaped first base member (11); a plate-shaped second base member (21) disposed facing the first base member (11); an electrically conductive resilient body (13) formed on an opposing surface of the first base member (11); a thread-like electrically conductive member (41) disposed between the first base member (11) and the second base member (21); a dielectric (42) formed at an outer periphery of the electrically conductive member (41); and an electrical conductor (22) formed on the second base member (21) following the electrically conductive member (41).

Description

[Technical Field]

[0001] The present invention relates to a load sensor that detects an externally applied load based on a change in capacitance. [Background technology]

[0002] Load sensors are widely used in fields such as industrial equipment, robots, and vehicles. In recent years, with the advancement of computer-based control technology and improvements in design, there has been progress in the development of electronic devices that make use of a variety of free-form surfaces, such as humanoid robots and automobile interior fittings. Accordingly, there is a demand for high-performance load sensors to be attached to each free-form surface.

[0003] The following Patent Document 1 describes a capacitance sensor including a dielectric layer and a plurality of electrode units arranged on both sides of the dielectric layer in the front-back direction. In this capacitance sensor, the electrode unit includes an insulating layer having a through-hole, an electrode layer arranged on one surface of the insulating layer in the front-back direction, and a jumper wiring layer arranged on the other surface of the insulating layer in the front-back direction and conducting with the electrode layer via the through-hole. A plurality of detection units (element units) are set in the area where the front electrode layer and the back electrode layer overlap. A load acting on the element unit is measured based on the capacitance obtained for each element unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 022258 Summary of the Invention [Problem to be solved by the invention]

[0005] In a load sensor such as that disclosed in Patent Document 1, when an object having a capacitance component, such as a finger, is brought close to the element from the outside, the capacitance component of the object becomes noise. In this case, the capacitance value of the element cannot be properly detected, and the load cannot be detected with high accuracy.

[0006] In view of the above problem, an object of the present invention is to provide a load sensor that can detect a load with high accuracy even when a capacitance component approaches. [Means for solving the problem]

[0007] A main aspect of the present invention relates to a load sensor, which includes a first base member having an elastic plate shape, a second base member having an elastic plate shape and disposed opposite the first base member, a conductive elastic body formed on the opposing surface of the first base member, a linear conductive member disposed between the first base member and the second base member, a dielectric body formed on the outer periphery of the conductive member, and a conductor formed on the second base member along the conductive member.

[0008] In the load sensor according to this aspect, the conductive member is sandwiched between the conductive elastic body and the conductor, and the conductive member is electrically shielded from both sides by the conductive elastic body and the conductor. This prevents the capacitance value of the element unit from unintentionally fluctuating even if a capacitance component approaches the load sensor. This allows for accurate load detection. [Effects of the Invention]

[0009] As described above, according to the present invention, it is possible to provide a load sensor that can detect a load with high accuracy even when a capacitance component approaches.

[0010] The effects and significance of the present invention will become more apparent from the following description of the embodiments, however, the embodiments shown below are merely examples of how the present invention can be implemented, and the present invention is not limited to the embodiments described below. [Brief explanation of the drawings]

[0011] [Figure 1] Fig. 1(a) is a perspective view schematically showing a first base member and a conductive portion formed on an opposing surface of the first base member according to embodiment 1. Fig. 1(b) is a perspective view schematically showing a state in which a conductive elastic body is disposed in the structure of Fig. 1(a) according to embodiment 1. [Figure 2] Fig. 2(a) is a perspective view schematically showing a second base member and conductors, wiring, terminal portions, and connectors formed on the opposing surface of the second base member according to embodiment 1. Fig. 2(b) is a perspective view schematically showing a state in which an insulating film is installed on the structure of Fig. 2(a) according to embodiment 1. [Figure 3] Fig. 3(a) is a perspective view schematically showing a state in which a conductor wire is arranged on the structure of Fig. 2(b) according to embodiment 1. Fig. 3(b) is a perspective view schematically showing a state in which the structure of Fig. 1(b) is placed on the structure of Fig. 3(a) according to embodiment 1. [Figure 4] FIG. 4 is a diagram schematically showing a cross section of the load sensor according to the first embodiment when cut along a plane parallel to the YZ plane at the center of the hole. [Figure 5] 5(a) and 5(b) are diagrams schematically showing a cross section of the element unit according to the first embodiment when cut at the center position of the element unit in the Y-axis direction along a plane parallel to the XZ plane. [Figure 6] FIG. 6 is a plan view schematically showing the arrangement of each part of the load sensor when viewed in the negative Z-axis direction according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing an example of the potential of each part according to the first embodiment. [Figure 8] Fig. 8(a) is a perspective view schematically showing a second base member and conductors, wiring, terminal portions, and connectors formed on the underside of the second base member according to a modified example of embodiment 1. Fig. 8(b) is a view schematically showing a cross section of the load sensor according to a modified example of embodiment 1 when cut along a plane parallel to the YZ plane at the center of the hole. [Figure 9]Fig. 9(a) is a perspective view schematically showing a first base member and a conductive portion formed on an opposing surface of the first base member according to embodiment 2. Fig. 9(b) is a perspective view schematically showing a state in which a conductive elastic body is disposed in the structure of Fig. 9(a) according to embodiment 2. [Figure 10] Fig. 10(a) is a perspective view schematically showing a second base member and conductors, terminals, wiring, and connectors formed on the opposing surface of the second base member according to embodiment 2. Fig. 10(b) is a perspective view schematically showing a state in which an insulating film is installed on the structure of Fig. 10(a) according to embodiment 2. [Figure 11] Fig. 11(a) is a perspective view schematically showing a state in which conductor wires are arranged in the structure of Fig. 10(b) according to embodiment 2. Fig. 11(b) is a perspective view schematically showing a state in which the structure of Fig. 9(b) is placed in the structure of Fig. 11(a) according to embodiment 2. [Figure 12] FIG. 12 is a diagram schematically illustrating a cross section of the load sensor according to the second embodiment, taken along a plane parallel to the XZ plane at the center of the hole. [Figure 13] FIG. 13 is a plan view schematically showing the arrangement of each part of the load sensor when viewed in the negative Z-axis direction according to the second embodiment. [Figure 14] FIG. 14 is a schematic diagram showing an example of the potential of each part according to the second embodiment. [Figure 15] Fig. 15(a) is a perspective view schematically showing a second base member and conductors, terminal portions, wiring, and connectors formed on the underside of the second base member according to a modified example of embodiment 2. Fig. 15(b) is a view schematically showing a cross section of the load sensor according to this modified example of embodiment 2 when cut along a plane parallel to the XZ plane at the center of the hole.

[0012] However, the drawings are for illustrative purposes only and do not limit the scope of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The load sensor according to the present invention can be applied to a load sensor for a management system or electronic device that performs processing in response to an applied load.

[0014] Examples of management systems include inventory management systems, driver monitoring systems, coaching management systems, security management systems, and nursing care / childcare management systems.

[0015] In an inventory management system, for example, a load sensor installed on a stock shelf detects the weight of the stock piled up, and detects the type and number of products on the stock shelf. This allows for efficient inventory management and labor savings in stores, factories, warehouses, etc. Furthermore, a load sensor installed inside a refrigerator detects the weight of food in the refrigerator, and detects the type, number, and amount of food in the refrigerator. This allows for automatic menu suggestions using the food in the refrigerator.

[0016] In a driver monitoring system, for example, a load sensor provided in the steering device monitors the load distribution of the driver on the steering device (for example, grip force, grip position, and pedal force). Also, a load sensor provided in the vehicle seat monitors the load distribution of the driver on the vehicle seat while seated (for example, center of gravity position). This makes it possible to provide feedback on the driver's driving state (drowsiness, psychological state, etc.).

[0017] In a coaching management system, for example, load sensors installed in the bottom of shoes monitor the load distribution on the soles of the feet, which can correct or guide the wearer to an appropriate walking or running state.

[0018] In a security management system, for example, load sensors installed on the floor detect the load distribution as a person passes through, and detect the person's weight, stride length, passing speed, shoe sole pattern, etc. By comparing this detected information with data, it becomes possible to identify the person who has passed through.

[0019] In a caregiving and childcare management system, for example, load sensors installed on bedding and toilet seats monitor the weight distribution of the human body relative to the bedding and toilet seat. This makes it possible to estimate what actions the person is about to take in relation to the position of the bedding or toilet seat and prevent falls or trips.

[0020] Examples of electronic devices include in-vehicle devices (car navigation systems, audio equipment, etc.), home appliances (electric kettles, induction cooking heaters, etc.), smartphones, electronic paper, electronic book readers, PC keyboards, game controllers, smartwatches, wireless earphones, touch panels, electronic pens, penlights, luminous clothing, musical instruments, etc. In electronic devices, a load sensor is provided in the input unit that receives input from the user.

[0021] The load sensor in the following embodiments is a capacitance type load sensor that is typically provided in the load sensors of the management systems and electronic devices described above. Such load sensors are sometimes called "capacitive pressure sensor elements," "capacitive pressure detection sensor elements," "pressure-sensitive switch elements," etc. The load sensors in the following embodiments are connected to an external detection circuit, and the load sensor and the detection circuit constitute a load detection device. The following embodiments are one embodiment of the present invention, and the present invention is not limited to the following embodiments in any way.

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, each drawing has X, Y, and Z axes which are orthogonal to each other. The Z axis direction is the height direction of the load sensor 1.

[0023] <Embodiment 1> FIG. 1(a) is a perspective view that schematically shows a first base member 11 and a conductive portion 12 formed on an opposing surface 11a (surface on the negative side of the Z axis) of the first base member 11. FIG.

[0024] The first base member 11 is an insulating member having elasticity. The first base member 11 is a plate-like member having flat surfaces on the positive side of the Z axis and the negative side of the Z axis. The planes on the positive side of the Z axis and the negative side of the Z axis of the first base member 11 are parallel to the XY plane. In this embodiment, the thickness of the first base member 11 is 0.5 mm. The elastic modulus of the first base member 11 is, for example, approximately 0.01 MPa to 10 MPa, and more specifically, approximately 1 MPa to 5 MPa.

[0025] The first base member 11 is made of a non-conductive resin material or a non-conductive rubber material. The resin material used for the first base member 11 is at least one resin material selected from the group consisting of styrene-based resins, silicone-based resins (such as polydimethylpolysiloxane (PDMS)), acrylic-based resins, rotaxane-based resins, and urethane-based resins. The rubber material used for the first base member 11 is at least one rubber material selected from the group consisting of silicone rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, polyisobutylene, ethylene propylene rubber, chlorosulfonated polyethylene, acrylic rubber, fluororubber, epichlorohydrin rubber, urethane rubber, and natural rubber.

[0026] The conductive portions 12 are formed on the opposing surface 11a of the first base member 11. Here, three conductive portions 12 are arranged on the opposing surface 11a of the first base member 11 so as to extend in the X-axis direction. The three conductive portions 12 are formed side by side in the Y-axis direction with a predetermined gap between them. The conductive portions 12 are made of a material with lower resistance than the conductive elastic body 13, which will be described later. The thickness of the conductive portions 12 is smaller than the thickness of the conductive elastic body 13, which will be described later. Furthermore, the width of the conductive portions 12 in the Y-axis direction is smaller than the width of the conductive elastic body 13, which will be described later.

[0027] The conductive portion 12 may be omitted. However, providing the conductive portion 12 to the conductive elastic body 13 (see FIG. 1(b)) described below can increase the conductivity of the structure consisting of the conductive elastic body 13 and the conductive portion 12 compared to the conductivity of the conductive elastic body 13 alone.

[0028] FIG. 1(b) is a perspective view that schematically shows a state in which a conductive elastic body 13 is arranged in the structure of FIG. 1(a).

[0029] The conductive elastic body 13 is formed on the opposing surface 11a of the first base member 11 so as to cover the conductive portion 12. The conductive elastic body 13 is Y The conductive portion 12 is formed on the opposing surface 11a so as to be positioned at approximately the middle position of the conductive elastic body 13 in the axial direction. Here, three conductive elastic bodies 13 are arranged on the opposing surface 11a of the first base member 11 so as to extend in the X-axis direction. The three conductive elastic bodies 13 are formed side by side in the Y-axis direction with a predetermined gap between them.

[0030] The conductive elastic body 13 is an elastic, conductive member. The conductive part 12 and the conductive elastic body 13 formed to cover the conductive part 12 are electrically connected. The conductive part 12 and the conductive elastic body 13 are made of a resin material with a conductive filler dispersed therein, or a rubber material with a conductive filler dispersed therein.

[0031] The resin material used for the conductive part 12 and the conductive elastic body 13 is, like the resin material used for the first base member 11 described above, at least one resin material selected from the group consisting of styrene-based resins, silicone-based resins (polydimethylpolysiloxane (e.g., PDMS)), acrylic-based resins, rotaxane-based resins, and urethane-based resins. The rubber material used for the conductive part 12 and the conductive elastic body 13 is, like the rubber material used for the first base member 11 described above, at least one rubber material selected from the group consisting of silicone rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, polyisobutylene, ethylene propylene rubber, chlorosulfonated polyethylene, acrylic rubber, fluororubber, epichlorohydrin rubber, urethane rubber, and natural rubber.

[0032] The conductive filler constituting the conductive portion 12 and the conductive elastomer 13 is at least one material selected from the group consisting of metal materials such as Au (gold), Ag (silver), Cu (copper), C (carbon), ZnO (zinc oxide), In2O3 (indium (III) oxide), and SnO2 (tin (IV) oxide), conductive polymer materials such as PEDOT:PSS (i.e., a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS)), and conductive fibers such as metal-coated organic fibers and metal wires (in a fibrous state).

[0033] In the first embodiment, the conductive filler constituting the conductive portion 12 is Ag (silver), and the conductive filler constituting the conductive elastic body 13 is C (carbon). This makes the conductive portion 12 more conductive than the conductive elastic body 13. Generally, materials with high conductivity are expensive, but this configuration allows for the saving of the conductive portion 12 with high conductivity, thereby reducing the cost of the conductive portion 12. Furthermore, generally, when an elastic body contains a material with high conductivity, the elastic modulus becomes high (the elastic body itself becomes hard). However, with this configuration, the width of the conductive portion 12 in the Y-axis direction at the position of the conductive member 41 (see FIGS. 5(a) and 5(b)), which will be described later, is small, so the elastic modulus of the structure consisting of the conductive portion 12 and the conductive elastic body 13 can be maintained low. Therefore, the electrostatic capacitance can be smoothly changed in response to the load.

[0034] In the first embodiment, the elastic modulus of the conductive elastic body 13 is set to be approximately the same as the elastic modulus of the first base member 11. Furthermore, since the conductive portion 12 contains Ag (silver) as a conductive filler, the elastic modulus of the conductive portion 12 is slightly higher than the elastic modulus of the conductive elastic body 13, for example, several MPa or more or several tens of MPa or more.

[0035] The conductive portion 12 and the conductive elastic body 13 are formed on the opposing surface 11a of the first base member 11 by a printing method such as screen printing, gravure printing, flexographic printing, offset printing, or gravure offset printing. After the conductive portion 12 is formed as shown in FIG. 1(a), the conductive elastic body 13 is formed so as to overlap the conductive portion 12 as shown in FIG. 1(b). These printing methods make it possible to form the conductive portion 12 and the conductive elastic body 13 on the opposing surface 11a of the first base member 11 with a thickness of approximately 0.001 mm to 0.5 mm. However, the method for forming the conductive portion 12 and the conductive elastic body 13 is not limited to the above-mentioned printing method.

[0036] FIG. 2(a) is a perspective view schematically showing the second base member 21, and the conductors 22, wiring 23, terminal portions 24, and connectors 25 formed on the opposing surface 21a (the surface on the positive side of the Z axis) of the second base member 21.

[0037] The second base member 21 is an insulating member. The second base member 21 is a plate-shaped member having flat surfaces on the positive side and the negative side of the Z axis, and the planes on the positive side and the negative side of the Z axis of the second base member 21 are parallel to the XY plane. As will be described later, the second base member 21 is disposed opposite the first base member 11. In the first embodiment, the thickness of the second base member 21 is 0.1 mm. The second base member 21 has high rigidity and an elastic modulus of 30 MPa or more.

[0038] The second base member 21 is made of a non-conductive resin material, and the resin material used for the second base member 21 is at least one resin material selected from the group consisting of polyurethane, polyethylene terephthalate, polyethylene, polycarbonate, polyimide, and the like.

[0039] The conductors 22, wiring 23, and terminal portion 24 are formed on the opposing surface 21a of the second base member 21. Here, six conductors 22 extending in the Y-axis direction are lined up with a predetermined gap in the X-axis direction, and three pairs of adjacent conductors 22 (pairs of conductors 22) are lined up in the X-axis direction. A wiring 23 extends from the Y-axis negative end of the conductor 22 on the X-axis negative side of a pair of conductors 22 toward the Y-axis negative side edge of the second base member 21. Adjacent pairs of conductors 22 are connected at a predetermined position in the Y-axis direction, and a terminal portion 24 protrudes from this connection position in the X-axis positive direction. One terminal portion 24 is arranged for each pair of conductors 22. The three terminal portions 24 are respectively arranged at positions facing the three conductive elastic bodies 13 shown in FIG. 1(b).

[0040] A pair of conductors 22, a wiring 23 connected to the pair of conductors 22, and a terminal portion 24 protruding from the pair of conductors 22 are integrally formed and electrically connected. The conductors 22, the wiring 23, and the terminal portion 24 are made of the same material, and like the conductive portion 12 described above, are made of a resin material with a conductive filler dispersed therein, or a rubber material with a conductive filler dispersed therein. In the first embodiment, the conductive filler constituting the conductors 22, the wiring 23, and the terminal portion 24 is Ag (silver). In the first embodiment, the elastic modulus of the conductors 22, the wiring 23, and the terminal portion 24 is approximately the same as the elastic modulus of the conductive portion 12 shown in FIG. 1(a).

[0041] The conductors 22, wiring 23, and terminal portions 24 are formed on the opposing surface 21a of the second base member 21 by a printing method such as screen printing, gravure printing, flexographic printing, offset printing, or gravure offset printing. These printing methods make it possible to form each portion on the opposing surface 21a of the second base member 21 with a thickness of about 0.001 mm to 0.5 mm. However, the method for forming each portion is not limited to the above printing method.

[0042] After the conductors 22, wirings 23, and terminal portions 24 are formed on the second base member 21, the connector 25 is installed on the side of the second base member 21 on the negative side of the Y axis so as to be connected to the three wirings 23. The connector 25 is a connector for connecting the wirings 23 to an external circuit.

[0043] FIG. 2(b) is a perspective view that schematically shows a state in which an insulating film 31 is placed on the structure of FIG. 2(a).

[0044] The insulating film 31 is an insulating member. The insulating film 31 is a sheet-like member and is parallel to the XY plane. In this embodiment, the thickness of the insulating film 31 is 0.03 mm. The elastic modulus of the insulating film 31 is 30 MPa or more.

[0045] The insulating film 31 is made of a non-conductive resin material, and the resin material used for the insulating film 31 is at least one resin material selected from the group consisting of polyurethane, polyethylene terephthalate, polyethylene, polycarbonate, polyimide, and the like.

[0046] 2(a) at an end (facing portion 24a, described later) in the positive direction of the X-axis of the terminal portion 24, a hole 31a is formed vertically penetrating the insulating film 31. As described later, the hole 31a is used to join the conductive elastic body 13 and the terminal portion 24.

[0047] FIG. 3(a) is a perspective view that schematically shows a state in which a conductor wire 40 is arranged in the structure of FIG. 2(b).

[0048] The conductor wires 40 are arranged in layers on the upper surface of the insulating film 31. Here, six conductor wires 40 extending in the Y-axis direction are lined up in the X-axis direction with a predetermined gap between them, and three pairs of adjacent conductor wires 40 (pairs of conductor wires 40) are lined up in the X-axis direction. In plan view, the six conductor wires 40 are arranged in the same positions as the six conductors 22 shown in FIG. 2(a). Two pairs of conductor wires 40 are connected to each other in a subsequent external detection circuit. Note that the pair of conductor wires 40 may also be connected at their ends on the positive side of the Y-axis.

[0049] The conductor wire 40 is made up of a linear conductive member 41 and a dielectric 42 formed on the surface of the conductive member 41. The configuration of the conductor wire 40 will be described later with reference to Figures 5(a) and (b).

[0050] 3(a), each conductor wire 40 is attached to the second base member 21 by a string so as to be movable in the direction in which the conductor wire 40 extends (Y-axis direction). Note that the string for attaching the conductor wire 40 is not limited to being attached to the second base member 21, and may also be attached to the first base member 11.

[0051] FIG. 3(b) is a perspective view that schematically shows the state in which the structure of FIG. 1(b) is installed on the structure of FIG. 3(a).

[0052] 1(b) is placed over the structure of Fig. 3(a) from above (the positive side of the Z axis), with the structure of Fig. 1(b) turned upside down, so that the conductor wires 40 come into contact with the conductive elastic bodies 13 arranged on the first base member 11.

[0053] Thereafter, thread 51 is sewn to the upper surface 11b of the first base member 11 and the lower surface 21b of the second base member 21 through the hole 31a. At this time, the conductive elastic body 13 is positioned above the hole 31a, and the terminal portion 24 is positioned below the hole 31a. Therefore, by sewing the thread 51 to the upper surface 11b and the lower surface 21b, the conductive elastic body 13 and the terminal portion 24 of the conductor 22 are pressed together and electrically connected. The thread 51 is made of chemical fiber, natural fiber, or a mixture thereof. The thread 51 in the first embodiment is made of a non-conductive material.

[0054] FIG. 4 is a diagram schematically showing a cross section of the load sensor 1 when cut along a plane parallel to the YZ plane at the center of the hole 31a.

[0055] Within the dashed line area shown in Figure 4, the thread 51, first base member 11, conductive portion 12, conductive elastic body 13, hole 31a, terminal portion 24, and second base member 21 form a connection structure C1 for electrically connecting the conductive elastic body 13 and the conductor 22.

[0056] The facing portion 13a of the conductive elastic body 13 is positioned above the hole 31a, and the facing portion 24a of the terminal portion 24 is positioned below the hole 31a. That is, the facing portions 13a and 24a face each other in the vertical direction (Z-axis direction) via the hole 31a. As described above, when the thread 51 is sewn to the first base member 11 and the second base member 21 through the hole 31a, the facing portions 13a and 24a are pressed together and electrically connected.

[0057] Returning to Fig. 3(b), thereafter, the outer periphery of the first base member 11 is connected to the second base member 21 with thread, thereby fixing the first base member 11 to the second base member 21. In this way, the load sensor 1 is completed as shown in Fig. 3(b).

[0058] The load sensor 1 is used with the first base member 11 facing upward (positive side of the Z axis) and the second base member 21 facing downward (negative side of the Z axis). In this case, the upper surface 11b of the first base member 11 is the surface to which the load is applied.

[0059] Here, the load sensor 1 has a plurality of element units A1 arranged in a matrix in a plan view. The load sensor 1 has a total of nine element units A1 arranged in the X-axis direction and the Y-axis direction. One element unit A1 corresponds to a region including an intersection point between the conductive elastic body 13 and a pair of conductor wires 40 arranged below the conductive elastic body 13. That is, one element unit A1 includes the first base member 11, the conductive unit 12, the conductive elastic body 13, the conductor wires 40, and the second base member 21 near the intersection point. When the lower surface of the load sensor 1 (the lower surface 21b of the second base member 21) is placed on a predetermined installation surface and a load is applied to the upper surface of the load sensor 1 (the upper surface 11b of the first base member 11) that constitutes the element unit A1, the electrostatic capacitance between the conductive elastic body 13 and the conductive member in the conductor wires 40 changes, and the load is detected based on the electrostatic capacitance.

[0060] 5(a) and (b) are the center positions of the element part A1 in the Y-axis direction. X FIG. 2 is a diagram schematically showing a cross section of the element portion A1 when cut along a plane parallel to the -Z plane.

[0061] Fig. 5(a) shows a state where no load is applied, and Fig. 5(b) shows a state where a load is applied. In Fig. 5(a) and (b), the lower surface 21b on the Z-axis negative side of the second base member 21 is placed on the installation surface.

[0062] 5(a) and 5(b), the conductor wire 40 is composed of a conductive member 41 and a dielectric 42 formed on the conductive member 41. The dielectric 42 is formed on the outer periphery of the conductive member 41 and covers the surface of the conductive member 41.

[0063] The conductive member 41 is a linear member. The conductive member 41 is made of, for example, a conductive metal material. Alternatively, the conductive member 41 may be made of a glass core wire and a conductive layer formed on its surface, or a resin core wire and a conductive layer formed on its surface. For example, the conductive member 41 may be made of a valve metal such as aluminum (Al), titanium (Ti), tantalum (Ta), niobium (Nb), zirconium (Zr), or hafnium (Hf), or tungsten (W), molybdenum (Mo), copper (Cu), nickel (Ni), silver (Ag), or gold (Au).

[0064] Dielectric 42 has insulating properties and is made of, for example, a resin material, a ceramic material, a metal oxide material, etc. Dielectric 42 may be at least one resin material selected from the group consisting of polypropylene resin, polyester resin (e.g., polyethylene terephthalate resin), polyimide resin, polyphenylene sulfide resin, polyvinyl formal resin, polyurethane resin, polyamideimide resin, polyamide resin, etc., or at least one metal oxide material selected from the group consisting of Al2O3, Ta2O5, etc.

[0065] 5(a), when no load is applied to the element portion A1, the force applied between the conductive elastic body 13 and the conductor wire 40 and the force applied between the insulating film 31 and the conductor wire 40 are substantially zero. From this state, when a load is applied downward to the upper surface 11b of the element portion A1 as shown in FIG. 5(b), the conductive elastic body 13, the conductive portion 12, and the first base member 11 are deformed by the conductor wire 40.

[0066] 5(b), when a load is applied, the conductor wire 40 is brought closer to the conductive elastic body 13 so as to be wrapped in the conductive elastic body 13, and the contact area between the conductor wire 40 and the conductive elastic body 13 increases. This causes a change in the capacitance between the conductive member 41 and the conductive elastic body 13. Then, the potential reflecting the change in capacitance in the element portion A1 is measured in an external circuit, and the load acting on the element portion A1 is calculated.

[0067] FIG. 6 is a plan view schematically showing the arrangement of each part of the load sensor 1 when viewed in the negative direction of the Z axis.

[0068] 6, for convenience, a layer consisting of first base member 11 and conductive elastic body 13, a layer consisting of conductor wires 40, a layer consisting of insulating film 31, and a layer consisting of second base member 21, conductor 22, and terminal portion 24 are shown side by side. The conductive elastic body 13 is shown as being seen through first base member 11.

[0069] As described above, nine element portions A1 arranged in a matrix are formed in the measurement area of ​​the load sensor 1. The nine element portions A1 correspond to nine positions where the conductive elastic body 13 intersects with the pair of conductor wires 40. Hereinafter, these nine element portions A1 will be referred to as A11, A12, A13, A21, A22, A23, A31, A32, and A33.

[0070] The conductive elastic bodies 13 corresponding to element portions A11 to A13 are connected to terminal portions 24 connected to a pair of conductors 22 on the negative side of the X-axis via holes 31a on the negative side of the X-axis. Similarly, the conductive elastic bodies 13 corresponding to element portions A21 to A23 are connected to terminal portions 24 connected to the central pair of conductors 22 via central holes 31a. The conductive elastic bodies 13 corresponding to element portions A31 to A33 are connected to terminal portions 24 connected to a pair of conductors 22 on the positive side of the X-axis via holes 31a on the positive side of the X-axis. The external circuit sequentially changes the element portion targeted for load detection at predetermined time intervals.

[0071] 7 is a schematic diagram showing the potentials of the respective parts when the element part A22 is the load detection target. As an example, the procedure for detecting the load applied to the element part A22 when the load is applied to the element part A22 from the upper surface 11b (see FIG. 3(b)) of the first base member 11 will be described below. explanation do.

[0072] The external circuit connects the central conductive elastic body 13 corresponding to the element portion A22 to ground, and applies a constant voltage (Vcc) to the conductive member 41 in the pair of conductor wires 40 corresponding to the element portion A22. Specifically, the external circuit connects the central pair of conductors 22 to ground, thereby connecting the central conductive elastic body 13 to ground. The external circuit also applies a constant voltage (Vcc) to the conductive member 41 in the central pair of conductor wires 40. As a result, the potential of the central conductive elastic body 13 becomes the ground potential (GND), and the potential V1 of the conductive member 41 in the central pair of conductor wires 40 gradually increases with a time constant corresponding to the capacitance of the element portion A22.

[0073] Furthermore, the external circuit sets the potentials of the conductive elastic bodies 13 and conductive members 41 other than the element portion A22 to the potential V1 that is the same as the central pair of conductive members 41 corresponding to the element portion A22. Specifically, the external circuit sets the potential V1 to the pair of conductors 22 on the positive side and negative side of the X-axis, thereby setting the potential V1 to the conductive elastic bodies 13 on the positive side and negative side of the Y-axis. The external circuit also sets the potential V1 to the conductive members 41 in the pair of conductor wires 40 on the positive side and negative side of the X-axis.

[0074] The external circuit measures the potential V1 of the central pair of conductive members 41 (the conductive members 41 corresponding to the element portion A22 to be detected) at a timing when a predetermined time has elapsed since the application of a constant voltage (Vcc). The external circuit calculates the capacitance of the element portion A22 based on the measured potential V1. Then, the external circuit obtains the load applied to the element portion A22 based on the calculated capacitance.

[0075] Here, if a layer made of the above-described conductor 22 is not arranged on the negative side (bottom side) of the layer made of the conductor wire 40 on the Z-axis, when a capacitance component approaches from below the conductor wire 40, the time constant changes from its original value due to the influence of the external capacitance component, and an error occurs in the change in potential V1. This reduces the accuracy of capacitance detection. In contrast, in the first embodiment, a layer made of the above-described conductor 22 is arranged on the negative side (bottom side) of the Z-axis of the layer made of the conductor wire 40, and potential V1 or ground potential (GND) is set to the conductor 22. As a result, the lower side of the conductor wire 40 is electrically shielded by the conductor 22. Therefore, even if a capacitance component approaches from below the conductor wire 40, an error in the change in potential V1 is suppressed. This maintains high accuracy of capacitance detection.

[0076] Furthermore, in the first embodiment, a layer made of the conductive elastic body 13 as described above is disposed on the Z-axis positive side (upper side) of the layer made of the conductor wire 40, and the conductive elastic body 13 is set to a potential V1 or a ground potential (GND). As a result, the upper side of the conductor wire 40 is electrically shielded by the conductive elastic body 13. Therefore, even if a capacitance component approaches from above the conductive elastic body 13, an error in the change in potential V1 is suppressed. This maintains high capacitance detection accuracy.

[0077] Furthermore, in the first embodiment, the conductors 22 are continuously arranged in the Y-axis direction directly below the conductive member 41 (in the negative Z-axis direction) along the conductor wires 40. Furthermore, the width of one conductor 22 in the X-axis direction is longer than the width of one conductor wire 40 in the X-axis direction. For example, the width of one conductor wire 40 in the X-axis direction is 0.06 mm to 1 mm, while the width of one conductor 22 in the X-axis direction is 1 mm to 2 mm. Specifically, the width of one conductor wire 40 in the X-axis direction is approximately 0.6 mm, while the width of one conductor 22 in the X-axis direction is approximately 1.2 mm. In this way, the conductors 22 are arranged so as to cover the conductor wires 40 in the width direction, and therefore the conductor wires 40 are reliably shielded by the conductors 22 from external capacitance components located below.

[0078] <Effects of the First Embodiment> According to the first embodiment, the following effects are achieved.

[0079] The conductive elastic body 13 is formed on the opposing surface 11a of the first base member 11, the linear conductive member 41 is disposed between the first base member 11 and the second base member 21, and the conductor 22 is formed on the second base member 21 along the conductive member 41. With this configuration, the conductive member 41 is sandwiched between the conductive elastic body 13 and the conductor 22, and therefore the conductive member 41 is electrically shielded from both sides by the conductive elastic body 13 and the conductor 22. This makes it possible to suppress unintentional fluctuations in the capacitance value of the element portion A1 even if a capacitance component approaches the load sensor 1. This allows for accurate load detection.

[0080] 2(a), the conductor 22 is formed on the opposing surface 21a of the second base member 21. With this configuration, the conductor 22 can be disposed close to the conductive elastic body 13. This allows the conductor 22 to be reliably shielded from the electrostatic capacitance component approaching from the second base member 21 side.

[0081] figure 3(a) As shown in Fig. 1, the insulating film 31 is disposed between the second base member 21 and the conductive member 41. This ensures insulation between the conductive member 41 and the conductor 22. This allows the load applied to the element portion A1 to be detected properly and stably.

[0082] 4, the load sensor 1 includes a connection structure C1 that electrically connects the conductive elastic body 13 and the conductor 22. As a result, compared to when voltage control is performed separately on the conductive elastic body 13 and the conductor 22, voltage control can be performed on both the conductive elastic body 13 and the conductor 22 using either the conductive elastic body 13 or the conductor 22 (the conductor 22 in the first embodiment). This allows the configuration of the load sensor 1 to be simplified.

[0083] The modulus of elasticity of the second base member 21 is higher than the modulus of elasticity of the first base member 11. In the first embodiment, the modulus of elasticity of the second base member 21 is 30 MPa or more.

[0084] Here, the modulus of elasticity of the first base member 11 is set low and the thickness of the first base member 11 is set small so that the load is appropriately applied to the element portion A1. As described above, the modulus of elasticity of the first base member 11 is set, for example, to about 0.01 MPa to 10 MPa, and the thickness is set, for example, to about 0.5 mm. If the first base member 11 is soft and thin like this, it is difficult to directly draw out the wiring for applying a voltage to the conductive elastic body 13 from the first base member 11.

[0085] In contrast, in this embodiment, as described above, the elastic modulus of the second base member 21 is set to 30 MPa or more, which is higher than that of the first base member 11. This makes it easy to draw out wiring from the hard second base member 21. Furthermore, since the conductive elastic body 13 and the conductor 22 are electrically connected by the connection structure C1, a predetermined potential can be set to each conductive elastic body 13 via the wiring 23 and connector 25 (see FIG. 2(a)) provided on the second base member 21.

[0086] If wiring for separately applying a voltage to the conductive elastic body 13 is drawn directly from the first base member 11, for example, the conductive portion 12 must be extended and drawn from the conductive elastic body 13 in the positive direction of the X-axis, and the conductive portion 12 must be connected to wiring leading to an external circuit in the region where the conductive portion 12 is drawn. In this case, space is required to connect the conductive portion 12 to the wiring leading to the external circuit, which increases the installation area of ​​the load sensor 1. In contrast, in this embodiment, the conductor 22 and the conductive elastic body 13 are connected within the measurement region, and a potential is set to the conductive elastic body 13 via the conductor 22, so the installation area of ​​the load sensor 1 can be reduced.

[0087] As shown in Fig. 4, the connection structure C1 electrically connects the conductive elastic body 13 and the conductor 22 by pressing the opposing portions 13a and 24a, which are arranged opposite each other on the opposing surfaces 11a and 21a of the first base member 11 and the second base member 21, against each other. This makes it possible to easily connect the conductive elastic body 13 and the conductor 22. Furthermore, because the two opposing portions 13a and 24a are configured to be in surface contact, it is possible to keep the electrical resistance at the interface between the conductive elastic body 13 and the conductor 22 low. This allows the electrostatic capacitance of the element portion A1 to be properly detected.

[0088] As shown in Fig. 4, the connection structure C1 presses the two opposing portions 13a, 24a together by sewing the first base member 11 and the second base member 21 together at the positions of the two opposing portions 13a, 24a. This allows the two opposing portions 13a, 24a to be easily pressed together. Furthermore, because the thread is strong and stretchable, the two opposing portions 13a, 24a can be pressed together stably with sufficient strength.

[0089] 6, a plurality of conductive elastic bodies 13 extending in one direction (X-axis direction) are formed on the first base member 11, aligned in the width direction (Y-axis direction), a plurality of conductive members 41 are aligned so as to intersect with the plurality of conductive elastic bodies 13, and the conductors 22 are continuously aligned along the conductive members 41. In this manner, the conductors 22 are aligned along the conductive members 41 without any gaps, which reliably prevents noise from being superimposed on the conductive members 41 from the second base member 21. Furthermore, compared to a case where one conductor having the same size as the region (measurement region) of all the element portions A1 is aligned, the conductors 22 are aligned only at positions corresponding to the conductive members 41, which stabilizes the potential of the conductors 22 and reduces the cost of the load sensor 1.

[0090] <Modification of the first embodiment> In the first embodiment, the conductor 22 is disposed on the upper surface (opposing surface 11a) of the second base member 21, but may be disposed on the lower surface 21b of the second base member 21.

[0091] Figure 8(a) is an oblique view schematically showing the second base member 21 and the conductor 22, wiring 23, terminal portion 24 and connector 25 formed on the lower surface 21b (the surface on the negative side of the Z axis) of the second base member 21 in this modified example.

[0092] The arrangement of the conductors 22, wiring 23, terminal portions 24, and connectors 25 in this modified example when viewed in the negative direction of the Z axis is the same as in the first embodiment. This modified example is configured in the same way as the first embodiment, except that the various parts installed on the second base member 21 are arranged on the underside 21b of the second base member 21. The insulating film 31 and conductor wire 40 in FIG. 3(a) are placed from above (the positive side of the Z axis) the inverted structure in FIG. 8(a), and the structure in FIG. 1(b) is then placed over it, inverted, and thread 52 is sewn on. In this way, the load sensor 1 is completed.

[0093] FIG. 8(b) is a diagram schematically showing a cross section of the load sensor 1 according to this modified example when cut along a plane parallel to the YZ plane at the center of the hole 31a.

[0094] The connection structure C1 in this case also electrically connects the conductive elastic body 13 and the conductor 22. The connection structure C1 is composed of the thread 52, the first base member 11, the conductive portion 12, the conductive elastic body 13, the hole 31a, the terminal portion 24, and the second base member 21, which are within the area indicated by the dashed line in FIG. 8(b).

[0095] However, in this modified example, the terminal portion 24 is provided on the lower surface 21b of the second base member 21, and therefore the conductive elastic body 13 and the terminal portion 24 cannot be pressure-welded. Therefore, in this modified example, a conductive thread 52 is hung between the first base member 11 and the second base member 21 at the position of the hole 31a. This electrically connects the conductive elastic body 13 and the terminal portion 24 (conductor 22).

[0096] <Effects of the Modification of the First Embodiment> According to this modification, in addition to the same effects as those of the first embodiment, the following effects are achieved.

[0097] The conductor 22 is formed on the surface (lower surface 21b) opposite to the opposing surface 21a of the second base member 21. With this configuration, compared to the first embodiment, the conductor 22 is spaced apart from the conductive member 41 by the thickness of the second base member 21. As a result, even if the potentials of the conductive member 41 and the conductor 22 differ during detection, as in the element portions A12, A22, and A32 in FIG. 7, for example, it is possible to suppress parasitic capacitance that occurs based on the potential difference between the conductive member 41 and the conductor 22. Therefore, the capacitance of the element portion A1 can be detected with high accuracy.

[0098] 8(b), the connection structure C1 electrically connects the conductive elastic body 13 and the conductor 22 by suspending a conductive member (thread 52) between the first base member 11 and the second base member 21. With this configuration, the conductive elastic body 13 and the conductor 22 can be electrically connected even when the conductor 22 is on the lower surface 21b of the second base member 21 as described above.

[0099] In this modified example, since the conductor 22 is formed on the lower surface 21b of the second base member 21, it is necessary to further place a film or the like to protect the load sensor 1 on the negative side of the conductor 22 in the Z axis direction. On the other hand, in the first embodiment, since the conductor 22 is formed on the upper surface (opposing surface 21a) of the second base member 21, it is not necessary to place a film or the like for protection on the negative side of the Z axis direction of the second base member 21. Therefore, from the viewpoint of making the load sensor 1 thinner, the first embodiment is preferable.

[0100] <Embodiment 2> In the above-described embodiment 1, the conductors 22 were arranged continuously along the conductor wire 40, but in embodiment 2, the conductors are arranged at the position of each element portion A1. In the following embodiment 2, components with the same reference numerals as in embodiment 1 are configured in the same way as in embodiment 1 unless otherwise specified.

[0101] 9(a) is a perspective view schematically showing a first base member 11 and a conductive portion 12 formed on the opposing surface 11a (the surface on the negative side of the Z axis) of the first base member 11 according to the second embodiment. In the second embodiment, the end of the first base member 11 on the positive side of the X axis is widened in the positive direction of the X axis. As a result, the conductive portion 12 formed on the opposing surface 11a of the first base member 11 is also widened in the positive direction of the X axis.

[0102] Fig. 9(b) is a perspective view schematically showing a state in which a conductive elastic body 13 is arranged in the structure of Fig. 9(a). The size of the conductive elastic body 13 in embodiment 2 is the same as that in embodiment 1. As a result, the conductive portion 12 is open upward on the positive side of the conductive elastic body 13 along the X axis.

[0103] Figure 10(a) is a perspective view that schematically shows the second base member 21, and the conductors 26, terminal portions 27, wiring 28, and connector 25 formed on the opposing surface 21a (the surface on the positive side of the Z axis) of the second base member 21.

[0104] The conductors 26, terminal portions 27, and wiring 28 are formed on the opposing surface 21a of the second base member 21. In the second embodiment, as in the first embodiment, element portions A1 (see FIG. 11(b)) are provided in a matrix. The conductors 26 are arranged at the positions of the element portions A1 and have approximately the same size as the element portions A1. Three conductors 26 aligned in the X-axis direction are connected to each other by connection portions 26a. Sets of three conductors 26 aligned in the X-axis direction are aligned in the Y-axis direction with a predetermined gap between them. The terminal portions 27 extend in the X-axis positive direction from the X-axis positive side end of the conductors 26 arranged on the X-axis positive side. The wiring 28 extends from the X-axis positive side end of the terminal portions 27 toward the Y-axis negative side edge of the second base member 21.

[0105] The three conductors 26, the two connecting portions 26a, the terminal portions 27 connected to the conductors 26, and the wiring 28 connected to the terminal portions 27 are integrally formed and electrically connected. The conductors 26, the connecting portions 26a, the terminal portions 27, and the wiring 28 are made of the same material, and like the above-described conductive portion 12, are made of a resin material with a conductive filler dispersed therein, or a rubber material with a conductive filler dispersed therein. In the second embodiment, the conductive filler constituting the conductors 26, the connecting portions 26a, the terminal portions 27, and the wiring 28 is Ag (silver).

[0106] The conductors 26, connecting portions 26a, terminal portions 27, and wiring 28 are formed on the facing surface 21a of the second base member 21 by a printing method such as screen printing, gravure printing, flexographic printing, offset printing, or gravure offset printing. These printing methods make it possible to form each portion on the facing surface 21a of the second base member 21 with a thickness of approximately 0.001 mm to 0.5 mm. However, the method for forming each portion is not limited to the above printing method.

[0107] After the conductors 26, connection portions 26a, terminal portions 27, and wiring 28 are formed on the second base member 21, the connector 25 is installed on the side of the second base member 21 on the negative side of the Y axis so as to be connected to the three wirings 28. The connector 25 is a connector for connecting the wirings 28 to an external circuit.

[0108] FIG. 10(b) is a perspective view that schematically shows a state in which an insulating film 31 is placed on the structure of FIG. 10(a).

[0109] The insulating film 31 has the same size as the second base member 21 in a plan view. A hole 31a that passes through the insulating film 31 from top to bottom is formed in the insulating film 31 at a position corresponding to the end (facing portion 27a, described later) of the terminal portion 27 in the positive direction of the X axis in Fig. 10(a). The hole 31a is used to join the conductive elastic body 13 and the terminal portion 27, as described later.

[0110] 11(a) is a perspective view schematically showing a state in which the conductor wire 40 is arranged in the structure of FIG.

[0111] FIG. 11(b) is a perspective view that schematically shows the state in which the structure of FIG. 9(b) is installed on the structure of FIG. 11(a).

[0112] 9(b) is placed over the structure of Fig. 11(a) from above (the positive side of the Z axis), with the structure of Fig. 9(b) turned upside down, so that the conductor wires 40 come into contact with the conductive elastic bodies 13 arranged on the first base member 11.

[0113] Thereafter, thread 51 is sewn to the upper surface 11b of the first base member 11 and the lower surface 21b of the second base member 21 through hole 31a. At this time, conductive elastic body 13 is positioned above hole 31a, and terminal portion 27 is positioned below hole 31a. Therefore, by sewing thread 51 to upper surface 11b and lower surface 21b, conductive elastic body 13 and terminal portion 27 are pressed together and electrically connected.

[0114] FIG. 12 is a diagram schematically showing a cross section of the load sensor 1 when cut along a plane parallel to the XZ plane at the center of the hole 31a.

[0115] In embodiment 2, a connection structure C1 that electrically connects the conductive elastic body 13 and the conductor 26 is formed by the thread 51, the first base member 11, the conductive portion 12, the hole 31a, the terminal portion 27, and the second base member 21 within the dashed line area shown in Figure 12.

[0116] The facing portion 12a of the conductive portion 12 connected to the conductive elastic body 13 is positioned above the hole 31a, and the facing portion 27a of the terminal portion 27 is positioned below the hole 31a. That is, the facing portions 12a and 27a face each other in the vertical direction (Z-axis direction) via the hole 31a. As described above, when the thread 51 is sewn to the first base member 11 and the second base member 21 through the hole 31a, the facing portions 12a and 27a are pressed together and electrically connected.

[0117] Returning to Fig. 11(b), thereafter, the outer periphery of the first base member 11 is connected to the second base member 21 with thread, thereby fixing the first base member 11 to the second base member 21. In this way, the load sensor 1 is completed as shown in Fig. 11(b). In the second embodiment, as in the first embodiment, a plurality of element portions A1 are formed that are arranged in a matrix in plan view.

[0118] FIG. 13 is a plan view schematically showing the arrangement of each part of the load sensor 1 according to the second embodiment when viewed in the negative direction of the Z axis.

[0119] 13, similarly to Fig. 6, for convenience, a layer consisting of first base member 11 and conductive elastic body 13, a layer consisting of conductor wires 40, a layer consisting of insulating film 31, and a layer consisting of second base member 21, conductor 26, terminal portion 27, and wiring 28 are shown side by side. The conductive elastic body 13 is shown as being seen through first base member 11.

[0120] The conductive elastic bodies 13 corresponding to element portions A11 to A13 are connected via holes 31a on the positive side of the X axis to terminal portions 27 connected to the set of three conductors 26 on the positive side of the Y axis. Similarly, the conductive elastic bodies 13 corresponding to element portions A21 to A23 are connected via central holes 31a to terminal portions 27 connected to the set of three conductors 26 in the center. The conductive elastic bodies 13 corresponding to element portions A31 to A33 are connected via holes 31a on the negative side of the X axis to terminal portions 27 connected to the set of three conductors 26 on the negative side of the Y axis.

[0121] 14 is a schematic diagram showing the potentials of the respective parts when the element part A22 is the load detection target. As an example, the procedure for detecting the load applied to the element part A22 when the load is applied to the element part A22 from the upper surface 11b of the first base member 11 (see FIG. 11(b)) will be described below. explanation do.

[0122] As in the first embodiment described with reference to FIG. 7, the external circuit connects the central conductive elastic body 13 corresponding to the element portion A22 to ground and applies a constant voltage (Vcc) to the conductive member 41 in the pair of conductor wires 40 corresponding to the element portion A22. Specifically, the external circuit connects the central set of three conductors 26 to ground, thereby connecting the central conductive elastic body 13 to ground. The external circuit also applies a constant voltage (Vcc) to the conductive member 41 in the central pair of conductor wires 40. As a result, the potential of the central conductive elastic body 13 becomes the ground potential (GND), and the potential V1 of the conductive member 41 in the central pair of conductor wires 40 gradually increases with a time constant corresponding to the capacitance of the element portion A22.

[0123] Furthermore, the external circuit sets the potentials of the conductive elastic bodies 13 and conductive members 41 other than the element portion A22 to be detected to potential V1, which is the same as that of the central pair of conductive members 41 corresponding to element portion A22. Specifically, the external circuit sets potential V1 to the set of three conductors 26 on the positive side of the Y-axis and the set of three conductors 26 on the negative side of the Y-axis, thereby setting potential V1 to the conductive elastic bodies 13 on the positive side and the negative side of the Y-axis. The external circuit also sets potential V1 to the conductive members 41 in the pair of conductor wires 40 on the positive side and the negative side of the X-axis.

[0124] The external circuit measures the potential V1 of the central pair of conductive members 41 (the conductive members 41 corresponding to the element portion A22 to be detected) at a timing when a predetermined time has elapsed since the application of a constant voltage (Vcc). The external circuit calculates the capacitance of the element portion A22 based on the measured potential V1. Then, the external circuit obtains the load applied to the element portion A22 based on the calculated capacitance.

[0125] In the second embodiment as well, a layer made of conductor 26 is disposed on the negative side (below) of the Z-axis of the layer made of conductor wire 40, and potential V1 or ground potential (GND) is set to conductor 26. As a result, the lower side of conductor wire 40 is electrically shielded by conductor 26. Furthermore, as in the first embodiment, the upper side of conductor wire 40 is electrically shielded by conductive elastic body 13. Therefore, even if a capacitance component approaches from the lower and upper sides of conductor wire 40, an error in the change in potential V1 is suppressed. This maintains high capacitance detection accuracy.

[0126] <Effects of the Second Embodiment> According to the second embodiment, in addition to the same effects as those of the first embodiment, the following effects are achieved.

[0127] 13, an element portion A1 for detecting a load is formed at each intersection of the plurality of conductive elastic bodies 13 and the plurality of conductive members 41, and a conductor 26 is disposed at the position of each element portion A1. With this configuration, the conductor 26 is formed to have approximately the same size as the area corresponding to the element portion A1, so that an effective electrical shield can be provided for the area of ​​the element portion A1.

[0128] <Modification of the second embodiment> In the second embodiment, the conductor 26 is disposed on the upper surface (opposing surface 11a) of the second base member 21, but may be disposed on the lower surface 21b of the second base member 21.

[0129] Figure 15(a) is an oblique view schematically showing the second base member 21, the conductor 26, the terminal portion 27, the wiring 28 and the connector 25 formed on the lower surface 21b (the surface on the negative side of the Z axis) of the second base member 21 in this modified example.

[0130] The arrangement of the conductors 26, connecting portions 26a, terminal portions 27, wiring 28, and connector 25 in this modified example when viewed in the negative direction of the Z axis is the same as in the second embodiment. This modified example is configured in the same way as in the second embodiment, except that the components installed on the second base member 21 are arranged on the underside 21b of the second base member 21. The insulating film 31 and conductor wire 40 in FIG. 11(a) are placed from above (the positive side of the Z axis) the inverted structure in FIG. 15(a), and the inverted structure in FIG. 9(b) is then placed over it, and thread 52 is sewn on. In this way, the load sensor 1 is completed.

[0131] FIG. 15(b) is a diagram schematically showing a cross section of the load sensor 1 according to this modified example when cut along a plane parallel to the XZ plane at the center of the hole 31a.

[0132] In this case, the connection structure C1 also has a conductive elastic body 13 and a conductive body 26 The connection structure C1 is composed of the thread 52, the first base member 11, the conductive portion 12, the hole 31a, the terminal portion 27, and the second base member 21 within the area enclosed by the dashed line in Figure 15(b).

[0133] However, in this modified example, since the terminal portion 27 is provided on the lower surface 21b of the second base member 21, the conductive elastic body 13 and the terminal portion 27 cannot be pressure-welded. Therefore, in this modified example, a conductive thread 52 is hung between the first base member 11 and the second base member 21 at the position of the hole 31a. This electrically connects the conductive elastic body 13 and the terminal portion 27 (conductor 26).

[0134] <Effects of the modified example of the second embodiment> According to this modification, in addition to the same effects as those of the second embodiment, the following effects are achieved.

[0135] The conductor 26 is formed on the surface (lower surface 21b) opposite to the opposing surface 21a of the second base member 21. With this configuration, the conductor 26 is spaced apart from the conductive member 41 by the thickness of the second base member 21, compared to the second embodiment. As a result, even if the potentials of the conductive member 41 and the conductor 26 differ during detection, as in the element portions A21, A22, and A23 of FIG. 14, for example, it is possible to suppress parasitic capacitance that occurs based on the potential difference between the conductive member 41 and the conductor 26. Therefore, the capacitance of the element portion A1 can be detected with high accuracy.

[0136] As shown in FIG. 15(b), the connection structure C1 electrically connects the conductive elastic body 13 and the conductor 26 by bridging a conductive member (thread 52) between the first base member 11 and the second base member 21. With this configuration, even when the conductor 26 is on the lower surface 21b of the second base member 21 as described above, the conductive elastic body 13 and the conductor 26 are electrically connected. 26 and can be electrically connected.

[0137] In this modified example, it is necessary to further place a film or the like to protect the load sensor 1 on the negative side of the Z axis of the conductor 26. On the other hand, in the second embodiment, it is not necessary to place a film or the like for protection on the negative side of the Z axis of the second base member 21. Therefore, from the viewpoint of making the load sensor 1 thinner, the second embodiment is preferable.

[0138] <Other change examples> In the first embodiment, the terminal portion 24 (see FIG. 4) joined to the conductive elastic body 13 by the thread 51 may have unevenness on the facing portion 24a (the surface on the positive side of the Z axis). When the facing portion 24a has unevenness in this way, the contact area between the facing portion 24a and the facing portion 13a of the conductive elastic body 13 becomes larger than when the surface is flat, and therefore the resistance value at the connection portion between the facing portion 24a and the facing portion 13a can be kept low.

[0139] Similarly, in the second embodiment, the terminal portion 27 (see FIG. 12) joined to the conductive portion 12 by the thread 51 may have unevenness on the facing portion 27a (the surface on the positive side of the Z axis). When the facing portion 27a has unevenness in this way, the contact area between the facing portion 27a and the facing portion 12a of the conductive portion 12 becomes larger than when the surface is flat, and therefore the resistance value at the connection portion between the facing portion 27a and the facing portion 12a can be kept low. Note that the facing portion 12a of the conductive portion 12 may have unevenness.

[0140] In a modification of the above-mentioned embodiment 1, as shown in Fig. 8(b), the conductive elastic body 13 and the terminal portion 24 are electrically connected by a conductive thread 52, and in a modification of the above-mentioned embodiment 2, as shown in Fig. 15(b), the conductive portion 12 and the terminal portion 27 are electrically connected by a conductive thread 52. However, this is not limiting, and instead of the thread 52, the two components to be connected as described above may be electrically connected by a conductive tubular member (grommet) having a hole penetrating from above to below, or a conductive screw.

[0141] In the above-described first and second embodiments, the non-conductive thread 51 is used, but the conductive thread 52 may be used. In this case, instead of the conductive thread 52, a conductive tubular member (grommet) or a conductive screw may be used.

[0142] In the modified examples of the first and second embodiments, the conductive thread 52 is used, but the non-conductive thread 51 In a modification of the first embodiment, for example, a hole may be provided in the second base member 21 at the position of the opposing portion 24a of the terminal portion 24 (see FIG. 8(b)), and the conductive elastic body 13 and the terminal portion 24 may be pressure-welded through this hole. In a modification of the second embodiment, for example, a hole may be provided in the second base member 21 at the position of the opposing portion 27a of the terminal portion 27 (see FIG. 15(b)), and the conductive portion 12 and the terminal portion 27 may be pressure-welded through this hole.

[0143] In the above-described first and second embodiments and their modified examples, the insulating film 31 does not necessarily have to be provided over the entire area as shown in Figures 6 and 13. However, in the above-described second embodiment, the insulating film 31 must be provided in this area so as to insulate the conductive portion 12 of the first base member 11 from the terminal portion 27 and wiring 28 of the second base member 21. Furthermore, although the conductive member 41 and the conductors 22 and 26 are not electrically connected by the dielectric 42, when the conductors 22 and 26 are disposed on the opposing surface 21a of the second base member 21 as in the first and second embodiments, it is preferable that the insulating film 31 be provided over the entire area.

[0144] In the above-described first and second embodiments and their modifications, the second base member 21 and the insulating film 31 may be made of an insulating rubber material. However, as described above, the cost can be reduced by making the second base member 21 and the insulating film 31 from a resin material.

[0145] In the above-described first and second embodiments and their modifications, the conductors are arranged on only one of the upper and lower surfaces of the second base member 21, but the conductors may be arranged on both the upper and lower surfaces. For example, in the second embodiment and its modifications, as shown in Fig. 13, the conductors 26 are arranged with gaps in between in the Y-axis direction, and therefore, other conductors may be further arranged along the conductor wires 40 on the surface opposite to the second base member 21 on which the conductors 26 are arranged, so as to fill these gaps.

[0146] In the above-described first and second embodiments and their modifications, the conductive elastic body 13 and the conductor formed on the second base member 21 do not necessarily have to be electrically connected. In this case, individual wiring is drawn out from the conductive elastic body 13 and the conductor formed on the second base member 21 so that voltages can be applied separately to the conductive elastic body 13 and the conductor formed on the second base member 21. However, from the viewpoint of simplifying the configuration, it is preferable that the conductive elastic body 13 and the conductor are electrically connected as described above.

[0147] In the modifications of the first and second embodiments, the thread 52 is a conductive material, and the first base member 11 and the second base member 21 are sewn together through the hole 31a in the insulating film 31. However, in these modifications, since the thread 52 is made of a conductive material, the insulating film 31 does not necessarily need to have the hole 31a.

[0148] In the above-described first and second embodiments and their modifications, as shown in Fig. 1(b) and Fig. 9(b), the load sensor 1 includes three pairs of conductive elastic bodies 13 and conductive portions 12, but it is sufficient if the load sensor 1 includes at least one pair of conductive elastic bodies 13 and conductive portions 12. For example, the load sensor 1 may include only one pair. In this case, the pair of conductor wires 40 and the conductors 22, 26 are changed depending on the layout of the element portion A1.

[0149] In the above-described first and second embodiments and their modifications, as shown in Fig. 3(a) and Fig. 11(a), the load sensor 1 includes three pairs of conductor wires 40, but it is sufficient to include at least one pair of conductor wires 40. For example, the load sensor 1 may include only one pair of conductor wires 40. In this case, the conductive elastic body 13, the conductive portion 12, and the conductors 22 and 26 are changed depending on the layout of the element portion A1.

[0150] In the above-described first and second embodiments and their modifications, the element portion A1 includes two conductor lines 40 aligned in the X-axis direction, but may include one or three or more conductor lines 40.

[0151] In the above-described first and second embodiments and their modifications, as shown in FIGS. 5(a) and 5(b), the conductor wire 40 is composed of one conductive member 41 and a dielectric 42 that covers the conductive member 41. However, the present invention is not limited to this. The conductor wire 40 may be composed of a twisted wire in which a plurality of the above-described conductor wires are bundled together. The conductor wire 40 may also be composed of a twisted wire in which a plurality of conductive members are bundled together and a dielectric that covers the twisted wire. In these cases, the flexibility of the conductor wire 40 can be increased, and the bending strength of the conductor wire 40 can be increased.

[0152] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical ideas set forth in the claims. [Explanation of symbols]

[0153] 1 Load sensor 11 First base member 11a Opposite side 12a Opposite part 13 Conductive elastic body 13a Opposite part 21 second base member 21a Opposite side 21b bottom surface (opposite side) 22 Conductors 24a Opposite part 26 Conductors 27a Opposite part 31 Insulating film 41 Conductive material 42 Dielectric 52 Thread (conductive material) A1, A11 to A33 element section C1 Connection structure

Claims

1. a first base member having an elastic plate shape; a plate-shaped second base member disposed opposite the first base member; a conductive elastic body formed on the opposing surface of the first base member; a linear conductive member disposed between the first base member and the second base member; a dielectric formed on the outer periphery of the conductive member; a conductor formed on the second base member along the conductive member, A load sensor characterized by:

2. The load sensor according to claim 1, The conductor is formed on the opposing surface of the second base member. A load sensor characterized by:

3. The load sensor according to claim 2, an insulating film disposed between the second base member and the conductive member; A load sensor characterized by:

4. The load sensor according to claim 1, The conductor is formed on a surface of the second base member opposite to the opposing surface. A load sensor characterized by:

5. The load sensor according to any one of claims 1 to 4, Further provided is a connection structure that electrically connects the conductive elastic body and the conductor. A load sensor characterized by:

6. The load sensor according to claim 5, The elastic modulus of the second base member is higher than the elastic modulus of the first base member. A load sensor characterized by:

7. 7. The load sensor according to claim 5, The elastic modulus of the second base member is 30 MPa or more. A load sensor characterized by:

8. The load sensor according to any one of claims 5 to 7, The connection structure electrically connects the conductive elastic body and the conductor by pressing opposing portions arranged opposite to each other on opposing surfaces of the first base member and the second base member against each other. A load sensor characterized by:

9. The load sensor according to claim 8, the connecting structure presses the opposing portions of the first base member and the second base member together by sewing the first base member and the second base member together at the positions of the opposing portions of the first base member and the second base member; A load sensor characterized by:

10. The load sensor according to any one of claims 5 to 7, The connection structure electrically connects the conductive elastic body and the conductor by bridging a conductive member between the first base member and the second base member. A load sensor characterized by:

11. The load sensor according to any one of claims 1 to 10, a plurality of the conductive elastic bodies extending in one direction are arranged in a width direction and formed on the first base member; A plurality of the conductive members are arranged side by side so as to intersect with the plurality of conductive elastic bodies, The conductor is disposed continuously along the conductive member. A load sensor characterized by:

12. The load sensor according to any one of claims 1 to 10, a plurality of the conductive elastic bodies extending in one direction are arranged in a width direction and formed on the first base member; A plurality of the conductive members are arranged side by side so as to intersect with the plurality of conductive elastic bodies, element portions for detecting a load are formed at the intersections of the plurality of conductive elastic bodies and the plurality of conductive members, The conductor is disposed at the position of each of the element portions. A load sensor characterized by:

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