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

Load Sensor

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

[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 multiple electrode units arranged on both sides of the dielectric layer in the front-to-back direction. In this capacitance sensor, the electrode unit includes an insulating layer having a through hole, an electrode layer arranged on one side of the insulating layer in the front-to-back direction, and a jumper wiring layer arranged on the other side of the insulating layer in the front-to-back direction and electrically connected to the electrode layer via the through hole. Multiple detection units (element units) are set in the area where the front electrode layer and the back electrode layer overlap. The load acting on the element unit is measured based on the capacitance obtained for each element unit.

[0004] International Publication No. 2017 / 022258

[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.

[0007] A main aspect of the present invention relates to a load sensor, comprising: 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.

[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.

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

[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 (e.g., grip force, grip position, pedal force). Also, a load sensor provided in the vehicle seat monitors the load distribution of the driver on the vehicle seat while seated (e.g., 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 / childcare management system, for example, load sensors installed on bedding and toilet seats monitor the distribution of load on 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 and toilet seat and prevent falls.

[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, smart watches, wireless earphones, touch panels, electronic pens, penlights, luminous clothing, musical instruments, etc. In electronic devices, a load sensor is provided in an input unit that receives input from a 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 is labeled with 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] First Embodiment FIG. 1A is a perspective view schematically illustrating a first base member 11 and a conductive portion 12 formed on an opposing surface 11 a (surface on the negative side of the Z axis) of the first base member 11 .

[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 (e.g., 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. 1B ), which will be described later, can increase the conductivity of the structure made up of the conductive elastic body 13 and the conductive portion 12 compared to the conductivity of the conductive elastic body 13 alone.

[0028] FIG. 1B is a perspective view that schematically shows a state in which a conductive elastic body 13 is disposed in the structure of FIG.

[0029] The conductive elastic bodies 13 are formed on the opposing surface 11a of the first base member 11 so as to cover the conductive portions 12. The conductive elastic bodies 13 are formed on the opposing surface 11a so that the conductive portions 12 are positioned at approximately the middle of the conductive elastic bodies 13 in the X-axis 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 portion 12 and the conductive elastic body 13 formed to cover the conductive portion 12 are electrically connected. The conductive portion 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 portion 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 portion 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 elastic body 13 may be, for example, Au (gold), Ag (silver), Cu (copper), C (carbon), ZnO (zinc oxide), In ２ O ３ (indium(III) oxide), and SnO ２The conductive material is at least one material selected from the group consisting of metal materials such as 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. However, 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 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, and is, 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 to 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] Figure 2(a) is an oblique 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, such as at least one resin material selected from the group consisting of polyurethane, polyethylene terephthalate, polyethylene, polycarbonate, and polyimide.

[0039] The conductors 22, wiring 23, and terminal portions 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, wiring 23 connected to the pair of conductors 22, and terminal portions 24 protruding from the pair of conductors 22 are integrally formed and electrically connected. The conductors 22, wiring 23, and terminal portions 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 embodiment 1, the conductive filler constituting the conductors 22, wiring 23, and terminal portions 24 is Ag (silver). In embodiment 1, the elastic modulus of the conductors 22, wiring 23, and terminal portions 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 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 with a thickness of approximately 0.001 mm to 0.5 mm on the facing surface 21a of the second base member 21. However, the method for forming each portion is not limited to the above-mentioned printing method.

[0042] After the conductors 22, wiring 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. 2B is a perspective view that schematically shows a state in which an insulating film 31 is provided on the structure of FIG.

[0044] The insulating film 31 is an insulating member. The insulating film 31 is a sheet-like member that 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, such as at least one resin material selected from the group consisting of polyurethane, polyethylene terephthalate, polyethylene, polycarbonate, and polyimide.

[0046] The insulating film 31 has a hole 31a that passes through the insulating film 31 from top to bottom at a position corresponding to the end (facing portion 24a, described later) of the terminal portion 24 in the positive direction of the X axis in Fig. 2(a). The hole 31a is used to join the conductive elastic body 13 and the terminal portion 24, as described later.

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

[0048] The conductor wires 40 are arranged in a stacked manner 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 a plan view, the six conductor wires 40 are arranged in the same positions as the six conductors 22 shown in FIG. 2( a). The two conductor wires 40 that make up a pair are connected to each other in a subsequent external detection circuit. Note that the pair of conductor wires 40 may also be connected at the 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] 3A, each conductor wire 40 is attached to the second base member 21 by a string so as to be movable in the direction of extension of the conductor wire 40 (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. 3B is a perspective view that schematically shows the state in which the structure of FIG. 1B is installed on the structure of FIG.

[0052] 1B is placed over the structure shown in Fig. 3A from above (the positive side of the Z axis) 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 constitute 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] 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.

[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. Each element unit A1 corresponds to a region including an intersection between the conductive elastic body 13 and a pair of conductor wires 40 arranged below the conductive elastic body 13. That is, each 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. 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 members in the conductor wires 40 changes, and the load is detected based on the electrostatic capacitance.

[0060] 5A and 5B are diagrams that schematically show a cross section of the element portion A1 when cut along a plane parallel to the YZ plane at the center position of the element portion A1 in the Y-axis direction.

[0061] 5A shows a state where no load is applied, and FIG. 5B shows a state where a load is applied, in which the lower surface 21b of the second base member 21 on the negative side of the Z axis 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] The dielectric 42 has insulating properties and is made of, for example, a resin material, a ceramic material, a metal oxide material, etc. The dielectric 42 may be at least one resin material selected from the group consisting of polypropylene resin, polyester resin (for example, polyethylene terephthalate resin), polyimide resin, polyphenylene sulfide resin, polyvinyl formal resin, polyurethane resin, polyamideimide resin, polyamide resin, etc., and may be Al ２ O ３ and Ta ２ O ５ and the like.

[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 11 b 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 applied to the element portion A1 is calculated.

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

[0068] 6, for convenience, the layer consisting of the first base member 11 and the conductive elastic body 13, the layer consisting of the conductor wires 40, the layer consisting of the insulating film 31, and the layer consisting of the second base member 21, the conductor 22, and the terminal portion 24 are shown side by side. The conductive elastic body 13 is shown as being seen through the 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 the 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 the central hole 31a. The conductive elastic bodies 13 corresponding to element portions A31 to A33 are connected to terminal portions 24 connected to the 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 various components when the element A22 is the load detection target. As an example, the following describes a procedure for detecting a load applied to the element A22 when the load is applied to the element A22 from the upper surface 11b of the first base member 11 (see FIG. 3B).

[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 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 lines 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) a predetermined time after the application of the constant voltage (Vcc). The external circuit calculates the capacitance of the element portion A22 based on the measured potential V1. The external circuit then 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 disposed on the negative side (bottom) 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, resulting in an error in the change in potential V1. This reduces the accuracy of capacitance detection. In contrast, in embodiment 1, a layer made of the above-described conductor 22 is disposed on the negative side (bottom) 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. This electrically shields the lower side of the conductor wire 40 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 positive Z-axis 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 along the conductor line 40 directly below the conductive member 41 (in the negative Z-axis direction). Furthermore, the width of one conductor 22 in the X-axis direction is longer than the width of one conductor line 40 in the X-axis direction. For example, the width of one conductor line 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 line 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 line 40 in the width direction, and therefore the conductor line 40 is reliably shielded by the conductors 22 from external capacitance components located below.

[0078] <Effects of 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, so that the conductive member 41 is electrically shielded from both sides by the conductive elastic body 13 and the conductor 22. This prevents the capacitance value of the element portion A1 from unintentionally fluctuating even if a capacitance component approaches the load sensor 1. This allows for accurate load detection.

[0080] 2A, 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] 2B, the insulating film 31 is disposed between the second base member 21 and the conductive member 41. This reliably insulates the conductive member 41 from the conductor 22. This allows the load applied to the element portion A1 to be detected appropriately 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 for the conductive elastic body 13 and the conductor 22, voltage control for both the conductive elastic body 13 and the conductor 22 can be performed using either the conductive elastic body 13 or the conductor 22 (the conductor 22 in the first embodiment). This simplifies the configuration of the load sensor 1.

[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 extend wiring for applying 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 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] In addition, when 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 needs to be extended and drawn from the conductive elastic body 13 in the positive direction of the X-axis, and the conductive portion 12 needs to 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 Figure 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 easy to 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, the electrical resistance at the interface between the conductive elastic body 13 and the conductor 22 can be kept low. This allows the electrostatic capacitance of the element portion A1 to be properly detected.

[0088] As shown in Figure 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 without gaps along the conductive members 41, which reliably prevents noise from being superimposed on the conductive members 41 from the second base member 21. Furthermore, compared to a case in which a single 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 First Embodiment> In the first embodiment, the conductor 22 is disposed on the upper surface (opposing surface 11 a ) of the second base member 21 , but it may be disposed on the lower surface 21 b 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 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. 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 the thread 52 is sewn on. In this way, the load sensor 1 is completed.

[0093] FIG. 8B 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.

[0095] However, in this modified example, the terminal portion 24 is provided on the lower surface 21b of the second base member 21, so 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 Modification of 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 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 Z-axis side of the conductor 22. 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 Z-axis side of the second base member 21. Therefore, from the viewpoint of configuring the load sensor 1 thin, the first embodiment is preferable.

[0100] <Embodiment 2> In the above-described embodiment 1, the conductors 22 are arranged continuously along the conductor line 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] 9A is a perspective view schematically illustrating 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] 9(b) is a perspective view schematically illustrating a state in which a conductive elastic body 13 is disposed 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 an oblique view schematically showing the second base member 21 and the conductor 26, terminal portion 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. 11B) are provided in a matrix. The conductors 26 are arranged at the positions of the respective 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 with a predetermined gap in the Y-axis direction. The terminal portions 27 extend in the positive X-axis direction from the positive X-axis end of the conductor 26 aligned on the positive X-axis side. The wiring 28 extends from the positive X-axis end of the terminal portions 27 toward the negative Y-axis side 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 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 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-mentioned 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. 10B is a perspective view that schematically shows a state in which an insulating film 31 is provided on the structure of FIG.

[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] Fig. 11A is a perspective view showing a state in which a conductor wire 40 is arranged in the structure of Fig. 10B. The conductor wire 40 has the same structure as in the first embodiment.

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

[0112] 9B is placed over the structure shown in Fig. 11A from above (the positive side of the Z axis), with the structure shown in Fig. 9B 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, 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 constitute a connection structure C1 that electrically connects the conductive elastic body 13 and the conductor 26.

[0116] The opposing portion 12a of the conductive portion 12 connected to the conductive elastic body 13 is positioned above the hole 31a, and the opposing portion 27a of the terminal portion 27 is positioned below the hole 31a. That is, the opposing portion 12a and the opposing portion 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 opposing portion 12a and the opposing portion 27a are pressed together and electrically connected.

[0117] 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 showing a schematic arrangement of each part of the load sensor 1 when viewed in the negative Z-axis direction according to the second embodiment.

[0119] 13, similarly to Fig. 6, for convenience, a layer consisting of the first base member 11 and the conductive elastic body 13, a layer consisting of the conductor wires 40, a layer consisting of the insulating film 31, and a layer consisting of the second base member 21, the conductors 26, the terminal portions 27, and the wiring 28 are shown side by side. The conductive elastic body 13 is shown as being seen through the 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 various components when the element A22 is the load detection target. As an example, the following describes a procedure for detecting a load applied to the element A22 when the load is applied to the element A22 from the upper surface 11b of the first base member 11 (see FIG. 11B).

[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 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 lines 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) a predetermined time after the application of the constant voltage (Vcc). The external circuit calculates the capacitance of the element portion A22 based on the measured potential V1. The external circuit then obtains the load applied to the element portion A22 based on the calculated capacitance.

[0125] In the second embodiment, a layer made of conductor 26 is also 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 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 Second Embodiment> In the second embodiment, the conductor 26 is disposed on the upper surface (opposing surface 11 a ) of the second base member 21 , but may be disposed on the lower surface 21 b of the second base member 21 .

[0129] Figure 15(a) is an oblique view schematically showing the second base member 21, the conductor 26, terminal portion 27, wiring 28 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.

[0130] The arrangement of the conductors 26, connecting portions 26a, terminal portions 27, wiring 28, and connector 25 of 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 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 of FIG. 11(a) are placed from above (the positive side of the Z axis) the inverted structure of FIG. 15(a), and the structure of FIG. 9(b) is then placed over it, inverted, and the 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] 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 hole 31a, the terminal portion 27, and the second base member 21, which are within the area indicated by the dashed line in FIG.

[0133] However, in this modified example, since the terminal portion 27 is provided on the lower surface 21b of the second base member 21, it is not possible to press the conductive elastic body 13 and the terminal portion 27 together. 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 Modification of 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 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. This makes it possible to suppress parasitic capacitance that occurs based on the potential difference between the conductive member 41 and the conductor 26, even when 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 . This allows the capacitance of the element portion A1 to be detected with high accuracy.

[0136] 15(b), the connection structure C1 electrically connects the conductive elastic body 13 and the conductor 26 by suspending 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 22 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 Modifications> 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 24 a (the surface on the positive side of the Z axis). When the facing portion 24 a has unevenness in this way, the contact area between the facing portion 24 a and the facing portion 13 a 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 24 a and the facing portion 13 a 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 27 a (the surface on the positive side of the Z axis). When the facing portion 27 a has unevenness in this way, the contact area between the facing portion 27 a and the facing portion 12 a of the conductive portion 12 is larger than when the surface is flat, so the resistance value at the connection portion between the facing portion 27 a and the facing portion 12 a can be kept low. Note that the facing portion 12 a of the conductive portion 12 may have unevenness.

[0140] In the modification of the first embodiment, 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 the modification of the second embodiment, 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 may be electrically connected by a conductive cylindrical member (grommet) having a hole penetrating from above to below, or a conductive screw.

[0141] In the 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 cylindrical member (grommet) or a conductive screw may be used.

[0142] In the modifications of the first and second embodiments, conductive thread 52 is used, but non-conductive thread 52 may also be used. In the modification of the first embodiment, for example, a hole may be provided in second base member 21 at the position of opposing portion 24a of terminal portion 24 (see FIG. 8(b)), and conductive elastic body 13 and terminal portion 24 may be pressure-welded through this hole. In the modification of the second embodiment, for example, a hole may be provided in second base member 21 at the position of opposing portion 27a of terminal portion 27 (see FIG. 15(b)), and conductive portion 12 and 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 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 second base member 21 and the insulating film 31 can be made of a resin material to reduce costs.

[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. However, 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 the Y-axis direction, and therefore, other conductors may be further arranged along the conductor wires 40 on the surface opposite 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 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 holes 31a in the insulating film 31. However, in these modifications, since the thread 52 is made of a conductive material, the holes 31a do not necessarily have to be provided in the insulating film 31.

[0148] In the 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 Figures 5(a) and 5(b), the conductor wire 40 is composed of a single 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.

[0153] REFERENCE SIGNS LIST 1 Load sensor 11 First base member 11a Opposing surface 12a Opposing portion 13 Conductive elastic body 13a Opposing portion 21 Second base member 21a Opposing surface 21b Lower surface (opposite surface) 22 Conductor 24a Opposing portion 26 Conductor 27a Opposing portion 31 Insulating film 41 Conductive member 42 Dielectric 52 Thread (conductive member) A1, A11 to A33 Element portion C1 Connection structure

Claims

1. A load sensor comprising: a first base member having an elastic plate shape; a second base member having a plate shape arranged opposite the first base member; a conductive elastic body formed on the opposing surface of the first base member; a linear conductive member arranged 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.

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

3. A load sensor according to claim 2, characterized in that it comprises an insulating film disposed between said second base member and said conductive member.

4. A load sensor according to claim 1, wherein the conductor is formed on the surface of the second base member opposite to the opposing surface.

5. A load sensor according to any one of claims 1 to 4, further comprising a connection structure for electrically connecting said conductive elastic body and said conductor.

6. A load sensor according to claim 5, wherein the modulus of elasticity of the second base member is higher than the modulus of elasticity of the first base member.

7. A load sensor according to claim 5 or 6, wherein the modulus of elasticity of the second base member is 30 MPa or more.

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

9. A load sensor according to claim 8, characterized in that the connection structure presses the opposing portions together by sewing the first base member and the second base member together at the positions of the two opposing portions.

10. A load sensor according to any one of claims 5 to 7, characterized in that 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.

11. A load sensor as claimed in any one of claims 1 to 10, characterized in that a plurality of the conductive elastic bodies extending in one direction are formed on the first base member in a line in the width direction, a plurality of the conductive members are arranged in a line so as to intersect with the plurality of conductive elastic bodies, and the conductors are arranged continuously along the conductive members.

12. A load sensor as claimed in any one of claims 1 to 10, characterized in that: a plurality of the conductive elastic bodies extending in one direction are formed on the first base member in a line in the width direction; a plurality of the conductive members are arranged in a line so as to intersect with the conductive elastic bodies; element parts for detecting load are formed at the intersections of the conductive elastic bodies and the conductive members, respectively; and the conductors are arranged at the positions of each of the element parts.