Load sensor

Abstract

A load sensor comprises a sheet-form first base member (10), a second base member (50) disposed facing the lower surface (12) of the first base member (10), a conductive elastic body (20) formed on the lower surface (12) of the first base member (10), a conductive member (60) integrally formed on the upper surface (51) of the second base member (50), and a dielectric body (70) disposed between the conductive elastic body (20) and the conductive member (60). The conductive member (60) has a surface shape that follows a ridge that is narrower at the tip than at the base.

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 load sensor configured with a wire sandwiched between two base members. The wire is configured by covering a conductor wire with a dielectric. A conductive elastic body is formed on one of the base members, and the wire is sewn with thread so that it overlaps the conductive elastic body. In this configuration, as the load increases, the contact area between the conductive elastic body and the wire increases, and therefore the capacitance between the conductor wire and the conductive elastic body increases. The load applied to the load sensor can be detected by detecting the value of this capacitance.

[0004] International Publication No. 2022 / 123976

[0005] In the load sensor described above, the wire is sewn to one of the base members, which can cause warping of the base member. When warping occurs in the base member, for example, the wire separates from the conductive elastic body formed on the base member, creating a gap. When a load is applied to this gap, the contact area between the wire and the conductive elastic body does not increase until the gap disappears. As a result, the load cannot be detected properly.

[0006] In view of the above problem, an object of the present invention is to provide a load sensor that can properly detect a load.

[0007] A main aspect of the present invention relates to a load sensor, comprising a sheet-like first base member, a second base member disposed opposite a lower surface of the first base member, a conductive elastic body formed on the lower surface of the first base member, a conductive member formed integrally on an upper surface of the second base member, and a dielectric body disposed between the conductive elastic body and the conductive member, wherein the conductive member has a surface shape that follows a ridge whose width is narrower at its tip than at its base.

[0008] In the load sensor according to this aspect, the conductive member is integrally formed on the upper surface of the second base member, preventing misalignment of the conductive member and preventing misalignment of the positional relationship between the conductive elastic body and the conductive member. Furthermore, because the conductive member has a surface shape that follows a ridge that is narrower at its tip than at its base, the contact area between the conductive elastic body and the conductive member via the dielectric increases as a load is applied. Therefore, the load can be properly detected based on the electrostatic capacitance between the conductive elastic body and the conductive member.

[0009] As described above, according to the present invention, it is possible to provide a load sensor that can properly detect a load.

[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] FIGS. 1(a) and 1(b) are perspective views schematically illustrating the configuration of a structure in a manufacturing process according to an embodiment. FIG. 2 is a perspective view schematically illustrating the configuration of a load sensor according to an embodiment. FIG. 3 is a plan view schematically illustrating the configuration of a load sensor according to an embodiment. FIGS. 4(a) and 4(b) are diagrams schematically illustrating a cross section of an element portion when a load sensor according to an embodiment is cut along a plane parallel to the X-Z plane. FIGS. 5(a) and 5(b) are perspective views respectively illustrating the configurations of Comparative Example 1 and an embodiment according to a first simulation. FIG. 6 is a graph illustrating the relationship between load and contact area according to the first simulation. FIGS. 7(a) to 7(c) are perspective views respectively illustrating the configurations of Comparative Examples 2 and 3 and an embodiment according to a second simulation. FIG. 8 is a graph illustrating the relationship between pressure and contact area according to the second simulation. FIGS. 9(a) and 9(b) are diagrams schematically illustrating a cross section of an element portion when a load sensor according to another configuration of a protrusion of an embodiment is cut along a plane parallel to the X-Z plane. FIG. 10 is a cross-sectional view illustrating the configuration of an embodiment according to a third simulation. FIG. 11 is a graph showing the relationship between load and contact area in a third simulation. FIG. 12 is a plan view schematically showing the configuration of a load sensor according to Modification Example 1. FIGS. 13(a) and 13(b) are plan views schematically showing the configuration of a load sensor according to Modification Example 2. FIGS. 14(a) and 14(b) are diagrams schematically showing a cross section of an element portion when the load sensor is cut along a plane parallel to the X-Z plane according to Modification Example 3. FIGS. 15(a) and 15(b) are diagrams schematically showing a cross section of an element portion when the load sensor is cut along a plane parallel to the X-Z plane according to Modification Example 3. FIGS. 16(a) and 16(b) are diagrams schematically showing a cross section of an element portion when the load sensor is cut along a plane parallel to the X-Z plane according to Modification Example 4. FIGS. 17(a) and 17(b) are diagrams schematically showing a cross section of an element portion when the load sensor is cut along a plane parallel to the X-Z plane according to Modification Example 5.

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

[0013] The present invention is applicable to an input unit for performing input according to an applied load. Specifically, the present invention is applicable to an input unit of an electronic device such as a PC keyboard, an input unit of a game controller, a surface portion for detecting an object by a robot hand, an input unit for inputting volume, air volume, light intensity, temperature, etc., an input unit of a wearable device such as a smart watch, an input unit of a hearable device such as a wireless earphone, an input unit of a touch panel, an input unit for adjusting the amount of ink in an electronic pen, an input unit for adjusting the light intensity or color in a penlight, an input unit for adjusting the light intensity in luminous clothing, and an input unit for adjusting the volume in a musical instrument, etc.

[0014] The following embodiment is a load sensor typically provided in the above-described device. Such a load sensor is called a "capacitive pressure sensor element," a "capacitive pressure detection sensor element," a "pressure-sensitive switch element," etc. The following embodiment is one embodiment of the present invention, and the present invention is not limited to the following embodiment.

[0015] 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 that are orthogonal to each other. The Z-axis direction is the height direction of the load sensor 1. For convenience, the positive direction of the Z-axis will be referred to as the upward direction.

[0016] FIG. 1A is a perspective view schematically showing the configuration of a structure 1a in the manufacturing process.

[0017] The structure 1 a includes a first base member 10 , a plurality of conductive elastic bodies 20 , a plurality of wirings 31 and 32 , and a plurality of electrode pads 33 .

[0018] The first base member 10 is an elastic sheet-like member. The first base member 10 has a rectangular shape in a plan view. The thickness of the first base member 10 is constant. The top surface 11 (the surface on the positive side of the Z axis) and the bottom surface 12 (the surface on the negative side of the Z axis) of the first base member 10 are both parallel to the X-Y plane. The bottom surface 12 is positioned facing downward during assembly and is the opposing surface facing the second base member 50, which will be described later. The first base member 10 is insulating and is made of, for example, a non-conductive resin material or a non-conductive rubber material.

[0019] A plurality of wirings 31 are disposed on the lower surface 12 of the first base member 10. Here, three wirings 31 are arranged side by side in the Y-axis direction. Each wiring 31 has a strip shape that is long in the X-axis direction, and is arranged side by side in the Y-axis direction with a predetermined gap between them. The three wirings 31 have the same width and thickness in the Y-axis direction. The wirings 31 are made of an elastic conductive material. The wirings 32 and the electrode pad 33 are disposed on the lower surface 12 of the first base member 10. One end of the wiring 32 is connected to the end of the wiring 31 on the negative side of the X-axis, and the other end of the wiring 32 is connected to the electrode pad 33.

[0020] The multiple conductive elastic bodies 20 are installed on the lower surface 12 of the first base member 10 so as to overlap the wiring 31. Here, three conductive elastic bodies 20 are arranged side by side in the Y-axis direction. Each conductive elastic body 20 has a strip-like shape that is long in the X-axis direction, and is lined up in the Y-axis direction with a predetermined gap between them. The three conductive elastic bodies 20 have the same width, length, and thickness. The conductive elastic bodies 20 are made of an elastic, conductive material. The width of the conductive elastic body 20 in the Y-axis direction is wider than the width of the wiring 31 in the Y-axis direction, and the length of the conductive elastic body 20 in the X-axis direction is slightly shorter than the length of the wiring 31 in the X-axis direction.

[0021] The conductive elastic body 20 and the wiring 31 are made of a resin material with a conductive filler dispersed therein, or a rubber material with a conductive filler dispersed therein. For example, C (carbon) is used as the conductive filler in the conductive elastic body 20, and Ag (silver) is used as the conductive filler in the wiring 31. Note that the fillers used in the conductive elastic body 20 and the wiring 31 are not limited to these, and may be fillers made of other conductive materials.

[0022] The conductive elastic body 20 and the wiring 31 are formed on the lower surface 12 of the first base member 10 by a printing method such as screen printing, gravure printing, flexographic printing, offset printing, or gravure offset printing. After the wiring 31 is formed on the lower surface 12 of the first base member 10, the conductive elastic body 20 is formed on the lower surface 12 so as to overlap the wiring 31. According to these printing methods, the conductive elastic body 20 and the wiring 31 can be formed on the lower surface 12 of the first base member 10 to a thickness of approximately 0.001 mm to 0.5 mm. However, the method of forming the conductive elastic body 20 and the wiring 31 is not limited to the printing method.

[0023] FIG. 1B is a perspective view that schematically shows the configuration of the structure 1b in the manufacturing process.

[0024] The structure 1 b includes a second base member 50 , a plurality of conductive members 60 , a plurality of dielectrics 70 , a plurality of wirings 81 , a plurality of wirings 82 , and a plurality of electrode pads 83 .

[0025] The second base member 50 is a flat, insulating, and rigid member. The second base member 50 has the same shape as the first base member 10 in a plan view, except for the connection portion 53. The second base member 50 has a constant thickness. The top surface 51 (the surface on the positive side of the Z axis) and the bottom surface 52 (the surface on the negative side of the Z axis) of the second base member 50 are both parallel to the X-Y plane. The top surface 51 is the surface facing the first base member 10. The second base member 50 is made of, for example, an insulating and rigid resin material. A connection portion 53 protruding in the negative direction of the Y axis is formed near one corner of the second base member 50.

[0026] A plurality of protrusions 90 are formed on the upper surface 51 of the second base member 50. Here, three protrusions 90 are arranged side by side in the X-axis direction. Each protrusion 90 has a long protrusion shape extending in the Y-axis direction, and is arranged side by side in the X-axis direction with a predetermined gap between them. The three protrusions 90 are identical in shape and size. Each protrusion 90 has a semi-cylindrical shape with its generatrix extending in the Y-axis direction. The protrusions 90 are formed integrally with the upper surface 51. For example, during film molding, the protrusions 90 are formed by grooves provided on the roll side to correspond to the protrusions 90.

[0027] The method for forming the protrusions 90 is not limited to the above, and may be injection molding, etc. Furthermore, the protrusions 90 may be formed integrally with the upper surface 51, and the material of the protrusions 90 may be different from the material of the second base member 50. When the protrusions 90 are made of a material different from that of the second base member 50, the protrusions 90 are also made of, for example, a resin material that is insulating and rigid.

[0028] The conductive member 60 is formed with a constant thickness on the surface of the protrusion 90. The upper surface of the conductive member 60 has the side shape of a cylinder. The conductive member 60 is made of, for example, a conductive metal material. A dielectric 70 is formed on the upper surface of the conductive member 60. The dielectric 70 is made of, for example, an insulating resin material, a ceramic material, a metal oxide material, or the like. The dielectric 70 is not formed near the end of the protrusion 90 on the negative side of the Y axis. As a result, the end of the conductive member 60 on the negative side of the Y axis is exposed and not covered by the dielectric 70, and wiring 81 is connected to this end.

[0029] The conductive member 60 and the dielectric 70 are formed by printing or vapor deposition. In the case of printing, the conductive member 60 is made of Ag (silver), and the dielectric 70 is made of an insulating resin material, for example. In the case of vapor deposition, the conductive member 60 is made of Al (aluminum), and the dielectric 70 is made of Al ２ O ３(aluminum oxide). The method and materials for forming the conductive member 60 and the dielectric 70 are not limited to those described above. The conductive member 60 and the dielectric 70 may be arranged by attaching a soft film material.

[0030] The wiring 81, 82 and the electrode pad 83 are disposed on the upper surface 51 of the second base member 50. One end of the wiring 81 is connected to the end of the conductive member 60 on the negative side of the Y axis, and the other end of the wiring 81 extends to the end of the connection portion 53 on the negative side of the Y axis. One end of the wiring 82 is connected to the electrode pad 83, and the other end of the wiring 82 extends to the end of the connection portion 53 on the negative side of the Y axis. The electrode pad 83 is disposed in a position overlapping the electrode pad 33 on the first base member 10 in a plan view when the first base member 10 and the second base member 50 are overlapped. The wiring 81, 82 extending to the end of the connection portion 53 are connected to an external detection circuit.

[0031] The lower surface 12 of the first base member 10 shown in Fig. 1(a) is placed opposite the upper surface 51 of the second base member 50 shown in Fig. 1(b), and the electrode pads 33 and 83 are electrically connected via solder or the like. The outer periphery of the first base member 10 and the outer periphery of the second base member 50 are then fixed together with thread or an adhesive material (not shown). In this way, the load sensor 1 is completed as shown in Fig. 2.

[0032] A flexible cable may be connected to extend the electrode pad 33 and the conductive member 60 to the outside. In this case, the wiring 82 and the electrode pad 83 are omitted, and an electrode pad for the conductive member 60 connected to the other end of the wiring 81 is disposed on the upper surface 51 of the second base member 50. This flexible cable includes electrode pads for connecting to the electrode pads 33 and the electrode pads for the conductive member 60. This flexible cable is sandwiched between the first base member 10 and the second base member 50 and is fixed to the first base member 10 with thread, a crimping member, or the like.

[0033] FIG. 2 is a perspective view schematically showing the configuration of the load sensor 1. As shown in FIG.

[0034] When using the load sensor 1, the load sensor 1 is installed with the first base member 10 facing upward (positive side of the Z axis) and the second base member 50 facing downward (negative side of the Z axis), with the negative direction of the Z axis in Fig. 2 corresponding to the vertically downward direction, i.e., the direction of gravity. In this case, the upper surface 11 of the first base member 10 (upper surface of the load sensor 1) is the surface to which the load is applied, and the lower surface 52 of the second base member 50 (lower surface of the load sensor 1) is installed on the installation surface. A base plate may also be installed on the lower surface 52 of the second base member 50.

[0035] When using the load sensor 1, the load sensor 1 may be installed with the second base member 50 facing upward (positive side of the Z axis) and the first base member 10 facing downward (negative side of the Z axis). In this case, the lower surface 52 of the second base member 50 (upper surface of the load sensor 1) becomes the surface to which the load is applied, and the upper surface 11 of the first base member 10 (lower surface of the load sensor 1) is installed on the installation surface.

[0036] In a plan view, the load sensor 1 has a plurality of element portions A arranged in a matrix. In the load sensor 1 of this embodiment, a total of nine element portions A arranged in the X-axis direction and the Y-axis direction are formed. For convenience, the range of the element portions A is indicated by a dashed line in Fig. 2.

[0037] FIG. 3 is a plan view schematically showing the configuration of the load sensor 1. As shown in FIG.

[0038] For convenience, each part of the load sensor 1 is shown in a see-through state in Figure 3. In a plan view, the conductive elastic body 20 and the wiring 31 extend linearly in the X-axis direction with a constant width in the Y-axis direction, while the conductive member 60, the dielectric 70, and the protrusion 90 extend linearly in the Y-axis direction with a constant width in the X-axis direction. One element portion A corresponds to a region including an intersection of the conductive elastic body 20 and the conductive member 60 disposed below the conductive elastic body 20. In Figure 3, for convenience, the conductive member 60 is shown with dots, and the range of the element portion A is shown with a dashed line. In a plan view, the range of the outer circumferential shape formed by the nine element portions A corresponds to the load detection surface of the load sensor 1.

[0039] When the lower surface of the load sensor 1 is placed on a predetermined installation surface and a load is applied to the upper surface of the load sensor 1, the capacitance between the conductive elastic body 20 and the conductive member 60 changes in the element part A to which the load is applied, and the load applied to the element part A is detected based on the capacitance.

[0040] 4A and 4B are diagrams that schematically show a cross section of the element portion A when the load sensor 1 is cut along a plane parallel to the XZ plane.

[0041] 4(a) shows a state where no load is applied, and FIG. 4(b) shows a state where a load is applied. In FIG. 4(a) and (b), the lower surface 52 of the second base member 50 is placed on the installation surface. In FIG. 4(a) and (b), the wiring 31 is omitted for convenience.

[0042] 4(a), the element portion A is composed of a first base member 10, conductive elastic body 20, wiring 31, dielectric 70, conductive member 60, protrusion 90, and second base member 50 near the intersection of one conductive elastic body 20 and one conductive member 60. The conductive elastic body 20, dielectric 70, and conductive member 60 constitute a pressure-sensing portion of the element portion A. The surface shapes of the dielectric 70, conductive member 60, and protrusion 90 are all arc-shaped when viewed in the Y-axis direction.

[0043] As shown in FIG. 4( a), when no load is applied to the element portion A, the conductive elastic body 20 and the dielectric 70 are in contact, and the conductive elastic body 20 is barely deformed. From this state, as shown in FIG. 4( b), when a load is applied downward to the upper surface 11 of the first base member 10, the conductive elastic body 20 is deformed by the dielectric 70, the conductive member 60, and the protrusion 90. At this time, the dielectric 70 is brought closer to the conductive elastic body 20 so as to be enveloped by the conductive elastic body 20, and the contact area between the conductive elastic body 20 and the dielectric 70 increases. This changes the capacitance between the conductive elastic body 20 and the conductive member 60. The potential reflecting the change in capacitance of the element portion A is then measured in the detection circuit, and the load applied to the element portion A is calculated.

[0044] In the no-load state, it is desirable that there be no gap between the conductive elastic body 20 and the dielectric 70, as shown in FIG. 4A . However, if a wire with a dielectric coating is used instead of the dielectric 70, conductive member 60, and protrusion 90, and the wire is sewn to the first base member 10 with thread (comparative example), warping of the first base member 10 may occur. If warping of the first base member 10 occurs, for example, the wire separates from the conductive elastic body 20, creating a gap. Therefore, when a load is applied to this separated position, the contact area between the conductive elastic body 20 and the wire does not increase until the gap disappears. As a result, it may become impossible to properly detect the load.

[0045] In contrast, in this embodiment, as shown in Fig. 4(a), the protrusion 90 is integrally formed with the second base member 50, and the conductive member 60 and the dielectric 70 are formed on the surface of the protrusion 90. This prevents the first base member 10 from warping due to the stitching thread, as in the comparative example, and makes it less likely for a gap to form between the conductive elastic body 20 and the dielectric 70. Therefore, the contact area between the conductive elastic body 20 and the dielectric 70 increases from the start of load application, allowing the load to be properly detected based on the electrostatic capacitance between the conductive elastic body 20 and the conductive member 60.

[0046] Next, a first simulation conducted by the inventors will be described. In the first simulation, the inventors investigated the difference in the increase in contact area between a configuration in which hemispherical protrusions are arranged in a row instead of the protrusions (Comparative Example 1) and a configuration in which the protrusions extend in one direction (Embodiment).

[0047] 5A and 5B are perspective views showing the configurations of Comparative Example 1 and the embodiment, respectively, according to the first simulation, in which the first base member 110 is shown in a see-through state for convenience.

[0048] As shown in FIG. 5A, in the configuration of Comparative Example 1, a first base member 110, a second base member 120, and multiple protrusions 131 are arranged in a square area in a plan view. The first base member 110 is an elastic member like the first base member 10. The second base member 120 is a rigid member like the second base member 50. The multiple protrusions 131 are arranged side by side with no gaps in the Y-axis direction on the upper surface of the second base member 120, and are made of a rigid material. The protrusions 131 are hemispherical and protrude upward.

[0049] The length L1 of one side of the first base member 110 in a plan view is 6 mm, the diameter R1 of the protrusion 131 is 0.3 mm, the height H1 of the protrusion 131 is 0.15 mm, the thickness T1 of the first base member 110 is 0.5 mm, and the thickness T2 of the second base member 120 is 1.15 mm. The modulus of elasticity of the first base member 110 is 3 MPa, and the modulus of elasticity of the second base member 120 and the protrusion 131 is 200 GPa.

[0050] As shown in FIG. 5( b ), in the configuration of this embodiment, a protruding streak 132 is provided instead of the multiple protrusions 131 in FIG. 5( a ). The protruding streak 132 is also made of a rigid material. The protruding streak 132 has a semi-cylindrical shape with its generatrix extending in the Y-axis direction. The width and height of the protruding streak 132 are the same as R1 and H1 in FIG. 5( a ), respectively. The size and elastic modulus of each component are the same as those in FIG. 5( a ).

[0051] In the first simulation, the change in contact area with respect to a load was verified by examining the change in the contact area between the first base member 110 and the protrusions 131 or the protrusions 132. Therefore, for convenience, the conductive elastic body, dielectric material, and conductive material are omitted from the first simulation. In the comparative example 1 and the embodiment, a load was applied to the entire upper surface of the first base member 110. In the comparative example 1, the contact area between the first base member 110 and the multiple protrusions 131 was calculated, and in the embodiment, the contact area between the first base member 110 and the protrusions 132 was calculated.

[0052] FIG. 6 is a graph showing the relationship between the load and the contact area in the first simulation.

[0053] 6, the horizontal axis represents the load applied to the upper surface of the first base member 110. The vertical axis represents the contact area between the first base member 110 and the plurality of protrusions 131 in the case of Comparative Example 1, and the contact area between the first base member 110 and the protrusions 132 in the case of the embodiment.

[0054] In both Comparative Example 1 and the embodiment, the contact area increases as the load increases. However, in Comparative Example 1, the increase in contact area as the load increases is small. Therefore, in a configuration in which semi-cylindrical structures made of protrusions 131, conductive members, and dielectrics are arranged in one direction, as in Comparative Example 1, the rate of increase in contact area is low, and it can be seen that there is a risk that the load cannot be detected properly.

[0055] On the other hand, in the embodiment, the increase in contact area in response to an increase in load is greater than in Comparative Example 1. This shows that the configuration in which the conductive member 60 and the dielectric 70 are formed on the surface of the protrusion 90, as in the embodiment, allows for proper load detection.

[0056] Next, a second simulation conducted by the inventors will be described. In the second simulation, the inventors examined the difference in the increase in contact area between a configuration in which hemispherical protrusions are arranged in a matrix (Comparative Examples 2 and 3) and a protrusion extending in one direction (embodiment).

[0057] 7A to 7C are perspective views showing the configurations of Comparative Examples 2 and 3 and the embodiment, respectively, relating to the second simulation. For convenience, the first base member 110 is shown in a see-through state in FIGS. 7A to 7C.

[0058] 7A and 7B, in the configurations of Comparative Examples 2 and 3, compared to the configuration of Fig. 5A, four quarter-sized protrusions 131 are arranged at predetermined intervals around the central protrusion 131. In Comparative Example 2, the length L2 of one side of the first base member 110 in a plan view is 0.6 mm, and the pitch P1 of the protrusions 131 is 0.42 mm. In Comparative Example 3, the length L3 of one side of the first base member 110 in a plan view is 0.9 mm, and the pitch P2 of the protrusions 131 is 0.63 mm.

[0059] 7(c), in the configuration of the embodiment, compared to the configuration of Fig. 5(b), the semi-cylindrical protrusion 132 whose generatrix extends in the Y-axis direction is divided into two by a plane parallel to the Y-Z plane, and the divided half of the protrusion 132 is arranged at a predetermined interval in the X-axis direction. In the embodiment, the length L3 of one side in a plan view of the first base member 110 is 0.9 mm, the same as in Fig. 7(b), and the interval P3 of the protrusions 132 is 0.6 mm.

[0060] In the second simulation, the size and elastic modulus of each part were the same as in the first simulation. Also in the second simulation, a load was applied to the entire upper surface of the first base member 110. In Comparative Examples 2 and 3, the contact area between the first base member 110 and the multiple protrusions 131 was calculated, and in the embodiment, the contact area between the first base member 110 and the protrusions 132 was calculated.

[0061] FIG. 8 is a graph showing the relationship between pressure and contact area in the second simulation.

[0062] 8, the horizontal axis represents the pressure obtained by dividing the load applied to the upper surface of the first base member 110 by the area of ​​the upper surface of the first base member 110. The vertical axis represents the contact area between the first base member 110 and the plurality of protrusions 131 in the cases of Comparative Examples 2 and 3, and the contact area between the first base member 110 and the protrusions 132 in the case of the embodiment.

[0063] In both Comparative Examples 2 and 3 and the embodiment, the contact area increases with increasing pressure. However, in Comparative Examples 2 and 3, the increase in contact area with increasing pressure is smaller than in the embodiment. Therefore, in a configuration in which semi-cylindrical structures made of protrusions 131, conductive members, and dielectrics are arranged in a matrix at predetermined intervals, as in Comparative Examples 2 and 3, the rate of increase in contact area is low, and it is understood that there is a risk that the load cannot be detected accurately.

[0064] On the other hand, in the embodiment, the increase in contact area in response to an increase in pressure is greater than in Comparative Examples 2 and 3. This shows that the configuration in which the conductive member 60 and the dielectric 70 are formed on the surface of the protrusion 90, as in the embodiment, allows for accurate load detection.

[0065] <Other Configurations of Protrusions> The shape of the protrusions 90 in the load sensor 1 is not limited to the semi-cylindrical shape shown in FIG. 4(a), and may be shapes such as those shown in FIGS. 9(a) and 9(b).

[0066] 9A and 9B are diagrams schematically showing a cross section of the element portion A when the load sensor 1 is cut along a plane parallel to the XZ plane, according to another configuration of the protrusion portion of the embodiment.

[0067] 4( a), the protrusion 90 in this configuration includes a central portion 91 and two inclined portions 92 located on both sides of the central portion 91 in the X-axis direction. The conductive member 60 includes a peak 61 located on the upper surface of the central portion 91 and two skirt portions 62 located on the upper surfaces of the two inclined portions 92, respectively.

[0068] The upper surfaces of the central portion 91 and the apex 61 have the side shape of a cylinder whose central axis AX1 is located on a plane parallel to the X-Y plane that includes the upper surface 51 of the second base member 50. The central portion 91 and the apex 61 are formed within an angle θ with respect to the central axis AX1. The upper surfaces of the inclined portion 92 and the skirt portion 62 are planes that are inclined with respect to the X-Y plane. The skirt portions 62 continue on both sides of the apex 61 in the width direction (X-axis direction) of the conductive member 60 and are gentler than the apex 61. Specifically, the inclination of the skirt portions 62 is the same as the inclination of the end portions of the apex 61 in the X-axis direction, and in a cross section, the tangent to the end portions of the apex 61 in the X-axis direction and the skirt portions 62 coincide.

[0069] Even in this configuration, when a load is applied downward to the upper surface 11 of the first base member 10 from the state shown in Fig. 9(a) as shown in Fig. 9(b), the conductive elastic body 20 is deformed by the dielectric 70, the conductive member 60, and the protrusion 90. At this time, compared to the configuration shown in Fig. 4(b), the increase in the contact area between the conductive elastic body 20 and the dielectric 70 corresponding to the change in load is greater due to the formation of the skirt portion 62. As a result, compared to the configuration shown in Fig. 4(b), the change in capacitance between the conductive elastic body 20 and the conductive member 60 is greater, thereby improving the detection sensitivity of the load applied to the element portion A.

[0070] Next, a third simulation performed by the inventors will be described. In the third simulation, the inventors verified the optimum range of the angle θ in the configuration shown in FIG.

[0071] FIG. 10 is a cross-sectional view showing the configuration of an embodiment according to a third simulation.

[0072] In the third simulation, a first base member 110, a second base member 120, a protrusion 132 extending in the Y-axis direction, and a conductive elastic body 140 are arranged. The first base member 110 and the conductive elastic body 140 are elastic members, similar to the first base member 10 and the conductive elastic body 20 described above. The second base member 120 and the protrusion 132 are rigid members, similar to the second base member 50 described above. The protrusion 132 has a configuration similar to the protrusion 90 shown in FIG. 9( a). That is, the protrusion 132 includes a central portion 132a and two inclined portions 132b located on both sides of the central portion 132a in the X-axis direction.

[0073] The height H1 of the protrusion 132 is 0.15 mm, and the thickness T3 of the conductive elastic body 140 is 0.01 mm. The length in the Y-axis direction of the first base member 110, the second base member 120, and the protrusion 132 is 1 mm, and the length in the Y-axis direction of the conductive elastic body 140 is 23 / 25 mm. The length in the X-axis direction of the first base member 110, the second base member 120, and the conductive elastic body 140 is set to be infinite. The elastic modulus of the conductive elastic body 140 is 80 MPa. The central portion 132a is formed within a range of angle θ with respect to the central axis AX1.

[0074] The size and elastic modulus of each part are the same as those in the first simulation. That is, the thickness T1 of the first base member 110 is 0.5 mm, and the thickness T2 of the second base member 120 is 1.15 mm. The elastic modulus of the first base member 110 is 3 MPa, and the elastic modulus of the second base member 120 and the protrusion 132 is 200 GPa.

[0075] In the third simulation, in a configuration in which the angle θ was changed to 10 different values ​​between 20° and 180° (see FIG. 11 ), a load was applied to the entire upper surface of the first base member 110, and the contact area between the conductive elastic body 140 and the protrusion 132 was calculated on either the positive X-axis side or the negative X-axis side of the central axis AX1. In other words, the contact area was calculated in a configuration in which the protrusion 132 was divided into two in the X-axis direction.

[0076] FIG. 11 is a graph showing the relationship between the load and the contact area in the third simulation.

[0077] 11, the horizontal axis represents the load applied to the upper surface of the first base member 110. The vertical axis represents the contact area between the first base member 110 and the protrusion 132. When the angle θ is 180°, the cross section of the protrusion 132 is semicircular.

[0078] Regardless of the value of the angle θ, the contact area increases as the load increases. In particular, the smaller the angle θ, the greater the rate of increase in the contact area. Therefore, it can be seen that the smaller the angle θ, the greater the load detection sensitivity can be.

[0079] However, when the angle θ is 20° or 30°, the slope of the graph changes significantly around a load of 0.2 N. When the angle θ is small, the rate of increase in the contact area until the first base member 110 contacts the entire upper surface of the central portion 132a of the protrusion 132 is likely to differ significantly from the rate of increase in the contact area after the first base member 110 contacts the upper surface of the inclined portion 132b of the protrusion 132. This makes it difficult to accurately detect the load. Furthermore, when the angle θ is small, such as 20° or 30°, the width of the protrusion 132 in the X-axis direction increases. Therefore, when multiple protrusions 132 are lined up in the X-axis direction, adjacent protrusions 132 in the X-axis direction are likely to interfere with each other.

[0080] In contrast, when the angle θ is 40° or greater, the slope of the graph does not change significantly, and the contact area increases roughly linearly with the load. Furthermore, when the angle θ is large, such as 40° or greater, it is possible to prevent adjacent protrusions 132 from interfering with each other. This makes it easier to detect the load accurately, and allows the element portions A to be arranged at a high density. Meanwhile, as the angle θ increases, the rate of increase in the contact area with increasing load decreases. From the above, it can be said that the angle θ is preferably between 40° and 60°, and more preferably, the angle θ is around 50°.

[0081] <Effects of the embodiment> According to the embodiment, the following effects are achieved.

[0082] As shown in Figures 4(a) and 9(a), the load sensor 1 includes a sheet-like first base member 10, a second base member 50 disposed opposite the lower surface 12 of the first base member 10, a conductive elastic body 20 formed on the lower surface 12 of the first base member 10, a conductive member 60 formed integrally with the upper surface 51 of the second base member 50, and a dielectric 70 disposed between the conductive elastic body 20 and the conductive member 60. The conductive member 60 has a surface shape that follows a protrusion that narrows from its base to its tip. That is, the conductive member 60 tapers in the height direction toward its tip, and the width of the conductive member 60 in the X-axis direction narrows in the direction away from a plane including the upper surface 51 of the second base member 50.

[0083] According to this configuration, the conductive member 60 is integrally formed on the upper surface 51 of the second base member 50, so the position of the conductive member 60 does not shift, and it is possible to prevent misalignment of the positional relationship between the conductive elastic body 20 and the conductive member 60. Furthermore, because the conductive member 60 has a surface shape that follows a ridge that is narrower at its tip than at its base, the contact area between the conductive elastic body 20 and the conductive member 60 via the dielectric 70 increases in response to the application of a load. Therefore, the load can be properly detected based on the electrostatic capacitance between the conductive elastic body 20 and the conductive member 60. Furthermore, because the position of the conductive member 60 is fixed, it is possible to prevent variation in the configuration of each element unit A.

[0084] As shown in Figures 4(a) and 9(a), a protrusion 90 that is narrower at the tip than at the base is formed on the upper surface 51 of the second base member 50, and the conductive member 60 is formed on the surface of the protrusion 90.

[0085] According to this configuration, the conductive member 60 is formed on the surface of the protrusion 90 provided on the upper surface 51 of the second base member 50, so that the precision of the shape and position of the conductive member 60 can be improved.

[0086] As shown in FIG. 9A, the conductive member 60 has a top 61 and bottom portions 62 that extend from both ends of the top 61 in the width direction (X-axis direction) of the conductive member 60 and are gentler than the top 61.

[0087] According to this configuration, when a load is applied, the contact area between the conductive elastic body 20 and the bottom portion 62 via the dielectric 70 can be increased more than in the configuration of Fig. 4(a) and the configuration of Fig. 10 in which the angle θ is 180°, thereby increasing the load detection sensitivity.

[0088] As shown in FIG. 9A, the top portion 61 is a curved surface having a curvature, and the bottom portion 62 is a flat surface.

[0089] With this configuration, as shown in FIG. 11, once the conductive elastic body 20 and the skirt portion 62 begin to come into contact with each other via the dielectric 70, the contact area between them can be made to increase linearly in response to an increase in load.

[0090] As shown in Figure 9 (a), the top 61 has the side shape of a cylinder with the central axis AX1 located on a plane including the upper surface 51 of the second base member 50, and the top 61 is formed in a range of 40° to 60° relative to the central axis AX1.

[0091] With this configuration, as shown in FIG. 11, the contact area between the conductive elastic body 20 and the bottom portion 62 via the dielectric 70 increases linearly in response to an increase in load, while preventing adjacent conductive members 60 from interfering with each other.

[0092] As shown in FIGS. 4A and 9A, the dielectric 70 is formed on the conductive member 60 so as to cover the surface of the conductive member 60 .

[0093] According to this configuration, the dielectric 70 can be disposed between the conductive elastic body 20 and the conductive member 60 simply by forming the dielectric 70 on the surface of the conductive member 60 .

[0094] As shown in Figure 3, multiple element parts A each comprising a first base member 10, a conductive elastic body 20, a dielectric 70, a conductive member 60 and a second base member 50 are arranged side by side in the Y-axis direction (first direction) in a planar view, and a conductive member 60 common to the multiple element parts A is arranged extending in the Y-axis direction (first direction).

[0095] According to this configuration, the load detection surface of the load sensor 1 can be widened, and the distribution of the load applied to the load detection surface can be grasped from the load detected by each element portion A. Furthermore, the configuration of the load sensor 1 can be simplified compared to when the conductive member 60 is individually disposed for each element portion A aligned in the Y-axis direction.

[0096] As shown in Figure 3, multiple sets of element parts A lined up in the Y-axis direction (first direction) are arranged in multiple rows in the X-axis direction (second direction) perpendicular to the Y-axis direction (first direction), and a conductive elastic body 20 common to the multiple element parts A lined up in the X-axis direction (second direction) is arranged extending in the X-axis direction (second direction).

[0097] This configuration simplifies the configuration of the load sensor 1 compared to arranging the conductive elastic body 20 individually for each element portion A aligned in the X-axis direction. Furthermore, because the element portions A are aligned in the X-axis direction and the Y-axis direction on the load detection surface of the load sensor 1, the element portions A can be arranged at high density.

[0098] <Modification 1> In the above embodiment, as shown in FIG. 3 , one set of conductive member 60, dielectric 70, and protrusion portion 90 is arranged for one element portion A, but multiple sets of conductive member 60, dielectric 70, and protrusion portion 90 may be arranged.

[0099] FIG. 12 is a plan view schematically showing the configuration of the load sensor 1 according to this modified example.

[0100] 3, in this modified example, two sets of conductive members 60, dielectric members 70, and protrusions 90 are arranged for one element portion A. In this modified example, too, each set of conductive members 60, dielectric members 70, and protrusions 90 extends in the Y-axis direction so as to be parallel to each other.

[0101] Here, by ensuring that the size (height and width in the X-axis direction) of the conductive configuration consisting of the conductive member 60, dielectric 70, and protrusion 90, and the gaps between the multiple conductive configurations, meet certain conditions, the range of change in capacitance with respect to load can be increased as the number of conductive configurations arranged in one element unit A increases, thereby widening the dynamic range of load detection. According to this modified example, since no misalignment of the conductive configurations occurs, the size and gaps of the conductive configurations can be set with high precision to meet certain conditions. This ensures a widening of the dynamic range of load detection.

[0102] <Modification 2> In the above embodiment, the conductive member 60, the dielectric 70, and the protrusion 90 are formed to extend in one direction, but the shapes of the conductive member 60, the dielectric 70, and the protrusion 90 are not limited to this.

[0103] 13( a), the conductive member 60, the dielectric 70, and the protrusion 90 extend linearly in the Y-axis direction, while their widths in the X-axis direction change depending on their positions in the Y-axis direction. Specifically, the widths in the X-axis direction of the conductive member 60, the dielectric 70, and the protrusion 90 increase within the element portion A. In this way, when the widths in the X-axis direction of the conductive member 60, the dielectric 70, and the protrusion 90 increase within the element portion A, even if a load is applied to the end of the element portion A, the load can be detected with high accuracy.

[0104] In the example shown in FIG. 13( b), the conductive member 60 and the protrusion 90 are meandering. Specifically, the conductive member 60 and the protrusion 90 are arranged in a meandering manner within the element portion A, and one dielectric 70 is arranged to cover three element portions A lined up in the Y-axis direction. In this way, when the conductive member 60, the dielectric 70, and the protrusion 90 are meandering within the element portion A, the conductive member 60 can be arranged evenly within the element portion A. This allows the load to be detected accurately even when it is applied to the end of the element portion A. Furthermore, since the overall length of the conductive member 60 within the element portion A can be increased, the sensitivity of the element portion A can also be improved.

[0105] 4(a) and 9(a), the surface shape of the conductive member 60 when viewed in the Y-axis direction is an arc shape or a shape combining an arc and a straight line, but the shape of the conductive member 60 is not limited to this. It is sufficient that the range of the conductive member 60 where the conductive elastic body 20 and the conductive member 60 can come into contact with each other via the dielectric 70 has a shape that tapers toward the upper end, and for example, the configurations shown in FIGS. 14(a) to 15(b) may be used.

[0106] In the example shown in Fig. 14(a), the cross section of the protrusion 90 is half an ellipse, and the surface shape of the conductive member 60 is elliptical when viewed in the Y-axis direction. In the example shown in Fig. 14(b), the protrusion 90 shown in Fig. 4(a) is elevated upward by a height H2. That is, the surface shapes of the conductive member 60 and the protrusion 90, when viewed in the Y-axis direction, are composed of an arc shape and straight lines extending downward from both ends of the arc shape.

[0107] In the example shown in Fig. 15(a), the cross section of the protrusion 90 is triangular, and the surface shape of the conductive member 60 is configured with a triangular outline when viewed in the Y-axis direction. In the example shown in Fig. 15(b), the cross section of the protrusion 90 is trapezoidal, and the surface shape of the conductive member 60 is configured with a trapezoidal outline when viewed in the Y-axis direction.

[0108] <Modification 4> In the above embodiment, as shown in Figures 4(a) and 9(a), the protrusion portion 90 is integrally formed with the upper surface 51 of the second base member 50, but if the upper surface of the conductive member 60 has a shape similar to that of the above embodiment, the protrusion portion 90 may be omitted.

[0109] In the example shown in Fig. 16(a), compared to the embodiment in Fig. 4(a), a conductive member 60 is provided instead of the protrusion 90. In the example shown in Fig. 16(b), compared to the embodiment in Fig. 9(a), a conductive member 60 is provided instead of the protrusion 90. That is, in this modified example, the conductive member 60 itself has a protrusion shape that is narrower at the tip than at the base.

[0110] <Modification 5> In the above embodiment, the dielectric 70 is formed on the conductive member 60 so as to cover the surface of the conductive member 60, but this is not limited thereto. The dielectric 70 may be disposed between the conductive elastic body 20 and the conductive member 60, and may be formed, for example, on the lower surface (the surface on the negative side of the Z axis) of the conductive elastic body 20, as shown in Figures 17(a) and (b).

[0111] In this case, the dielectric 70 is made of an insulating material that is deformable together with the conductive elastic body 20. For example, the material that makes up the dielectric 70 is polyurethane rubber, silicone rubber, natural rubber, etc. The dielectric 70 is formed on the surface of the conductive elastic body 20 with a thickness of, for example, about 8 μm to 30 μm. In this modified example, the capacitance between the conductive elastic body 20 and the conductive member 60 changes depending on the load, so that the load applied to the element portion A can be detected, as in the above embodiment.

[0112] 4(a), the protrusion 90 has a semi-cylindrical shape, but the protrusion 90 may be a part of a cylindrical shape formed near the upper end of the semi-cylindrical shape. Similarly, in the configuration shown in Fig. 9(a), the central axis AX1 is located on a plane parallel to the X-Y plane including the upper surface 51 of the second base member 50, but the protrusion 90 may be located above or below a plane parallel to the X-Y plane including the upper surface 51.

[0113] In the configuration shown in FIG. 4A, the skirt 62 is flat, but is not limited to this and may be a curved surface that is recessed downward or a curved surface that protrudes upward.

[0114] In the above embodiment and modified examples 1 to 4, the dielectric 70 is arranged along the shape of the protrusion 90 in plan view, but may be arranged so as to span all of the element portions A. Also, in modified example 5, the dielectric 70 is arranged in the region of the conductive elastic body 20 in plan view, but may be arranged so as to span all of the element portions A.

[0115] In the above embodiment and modified examples 1 to 5, three element parts A are arranged in a row in each of the X-axis direction and the Y-axis direction, but the number of element parts A arranged in a row in each of the X-axis direction and the Y-axis direction may be one, two, four or more.

[0116] In the above embodiment and modified examples 1 to 5, the conductive elastic body 20 is disposed on the lower surface 12 of the first base member 10, and the conductive member 60 is disposed on the upper surface 51 of the second base member 50. However, this is not limiting, and the conductive elastic body 20 may be disposed on the upper surface 51 of the second base member 50, and the conductive member 60 may be disposed on the lower surface 12 of the first base member 10.

[0117] In the above embodiment and modified examples 1 to 5, the direction in which the conductive elastic body 20 extends and the direction in which the conductive member 60 extends are perpendicular to each other, but this is not limiting, and the angle between these directions may be an angle other than 90°. In other words, the conductive member 60 may intersect the conductive elastic body 20 at an angle.

[0118] 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.

[0119] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0120] (Technology 1) A load sensor comprising: a sheet-like first base member; a second base member arranged opposite the underside of the first base member; a conductive elastic body formed on the underside of the first base member; a conductive member formed integrally on the upper surface of the second base member; and a dielectric body arranged between the conductive elastic body and the conductive member, wherein the conductive member has a surface shape that follows a protrusion that is narrower at its tip than at its base.

[0121] According to this technology, the conductive member is integrally formed on the upper surface of the second base member, preventing misalignment of the conductive member and preventing misalignment of the positional relationship between the conductive elastic body and the conductive member. Furthermore, because the conductive member has a surface shape that follows a ridge that is narrower at its tip than at its base, the contact area between the conductive elastic body and the conductive member via the dielectric increases as a load is applied. Therefore, the load can be properly detected based on the electrostatic capacitance between the conductive elastic body and the conductive member.

[0122] (Technology 2) The load sensor according to Technology 1, characterized in that a protrusion having a width narrower at its tip than at its base is formed on the upper surface of the second base member, and the conductive member is formed on the surface of the protrusion.

[0123] According to this technique, the conductive member is formed on the surface of the protrusion provided on the upper surface of the second base member, so that the precision of the shape and position of the conductive member can be improved.

[0124] (Technology 3) In the load sensor according to Technology 1 or 2, the conductive member has a top portion and bottom portions that continue on both sides of the top portion in the width direction of the conductive member and are gentler than the top portion.

[0125] This technique can increase the contact area between the conductive elastic body and the bottom part via the dielectric when a load is applied, thereby improving the load detection sensitivity.

[0126] (Technology 4) The load sensor according to Technology 3, wherein the top portion is a curved surface having a curvature, and the bottom portion is a flat surface.

[0127] According to this technique, once the conductive elastic body and the skirt portion start to come into contact with each other via the dielectric, the contact area between them can be made to increase linearly in response to an increase in load.

[0128] (Technology 5) In the load sensor described in Technology 3 or 4, the top has a side shape of a cylinder whose central axis is located on a plane including the upper surface of the second base member, and the top is formed in a range of 40° to 60° with respect to the central axis.

[0129] According to this technique, the contact area between the conductive elastic body and the bottom portion via the dielectric increases linearly in response to an increase in load, while preventing adjacent conductive members from interfering with each other.

[0130] (Technology 6) The load sensor according to Technology 1 or 2, wherein the surface shape of the conductive member is an arc shape when viewed in a direction in which the conductive member extends along the ridge.

[0131] (Technology 7) The load sensor according to any one of Technologies 1 to 6, wherein the conductive member extends linearly with a constant width in a plan view.

[0132] (Technology 8) The load sensor according to any one of Technologies 1 to 6, wherein, in a plan view, the conductive member extends linearly in one direction and has a width that changes depending on the position in that direction.

[0133] (Technology 9) The load sensor according to any one of Technologies 1 to 6, wherein the conductive member is meandering in a plan view.

[0134] (Technology 10) The load sensor according to any one of Technologies 1 to 9, wherein the dielectric is formed on the conductive member so as to cover a surface of the conductive member.

[0135] According to this technique, the dielectric can be disposed between the conductive elastic body and the conductive member simply by forming the dielectric on the surface of the conductive member.

[0136] (Technology 11) A load sensor according to any one of technologies 1 to 10, characterized in that a plurality of element units each including the first base member, the conductive elastic body, the dielectric, the conductive member, and the second base member are arranged side by side in a first direction in a plan view, and the conductive member common to a plurality of the element units is arranged extending in the first direction.

[0137] According to this technique, the load detection surface of the load sensor can be widened, and the distribution of the load applied to the load detection surface can be grasped from the load detected by each element. Furthermore, the configuration of the load sensor can be simplified compared to when a conductive member is individually disposed for each element arranged in the first direction.

[0138] (Technology 12) A load sensor according to Technology 11, characterized in that a plurality of sets of element parts aligned in the first direction are arranged in a second direction perpendicular to the first direction, and the conductive elastic body common to the plurality of element parts aligned in the second direction is arranged extending in the second direction.

[0139] This technique simplifies the configuration of the load sensor compared to disposing a conductive elastic body individually for each element portion aligned in the second direction. Furthermore, since the element portions are aligned in the first and second directions on the load detection surface of the load sensor, the element portions can be arranged at high density.

[0140] REFERENCE SIGNS LIST 1 load sensor 10 first base member 12 lower surface 20 conductive elastic body 50 second base member 51 upper surface 60 conductive member 61 top portion 62 bottom portion 70 dielectric material 90 protrusion portion A element portion AX1 central axis

Claims

1. A load sensor comprising: a sheet-like first base member; a second base member disposed opposite the underside of the first base member; a conductive elastic body formed on the underside of the first base member; a conductive member formed integrally on the upper surface of the second base member; and a dielectric body disposed between the conductive elastic body and the conductive member, wherein the conductive member has a surface shape that follows a ridge that is narrower at its tip than at its base.

2. A load sensor as claimed in claim 1, characterized in that a protrusion having a narrower width at its tip than at its base is formed on the upper surface of the second base member, and the conductive member is formed on the surface of the protrusion.

3. A load sensor according to claim 1, wherein the conductive member has a top portion and bottom portions that continue on both sides of the top portion in the width direction of the conductive member and are gentler than the top portion.

4. A load sensor according to claim 3, wherein the top portion is a curved surface having a curvature, and the bottom portion is a flat surface.

5. A load sensor as described in claim 4, wherein the top has the shape of a side surface of a cylinder whose central axis is located on a plane including the upper surface of the second base member, and the top is formed at an angle of 40° to 60° relative to the central axis.

6. A load sensor according to claim 1, wherein the surface shape of the conductive member is an arc shape when viewed in the direction in which the conductive member extends.

7. A load sensor according to claim 1, wherein, in a plan view, the conductive member extends linearly with a constant width.

8. A load sensor according to claim 1, wherein, in a plan view, the conductive member extends linearly in one direction, and the width of the conductive member varies depending on the position in that direction.

9. The load sensor according to claim 1, wherein the conductive member is meandering in plan view.

10. A load sensor according to claim 1, wherein the dielectric is formed on the conductive member so as to cover the surface of the conductive member.

11. A load sensor as described in claim 1, characterized in that a plurality of element parts each comprising the first base member, the conductive elastic body, the dielectric, the conductive member and the second base member are arranged side by side in a first direction in a plan view, and the conductive member common to a plurality of the element parts is arranged extending in the first direction.

12. A load sensor as described in claim 11, characterized in that a plurality of sets of element parts aligned in the first direction are arranged in a second direction perpendicular to the first direction, and the conductive elastic body common to the plurality of element parts aligned in the second direction is arranged extending in the second direction.

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