Electrode structure

Abstract

To make it easy to inhibit a conducting wire from imposing a mechanical load on a conducting cloth in a condition where the conducting wire is attached to a rim of a steering wheel.SOLUTION: An electrode structure 110 includes: a substrate 111 having a first area A1 which is constituted so as to be fitted in a groove 31 of a rim 31 and is marked, and a second area A2 which is constituted so as to be arranged along a part of the rim 31 other than the groove 31b and is different from the first area A1; and one or more conducting wires 114 arranged on the substrate 111. The one or more conducting wires 114 are arranged over the first area A1 and the second area A2. The one or more conducting wires 114 are arranged in the first area A1 at a wiring density lower than that in the second area A2.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] The present disclosure relates to an electrode structure used in a capacitive grip sensor, and to the grip sensor. [Background technology]

[0002] Patent Document 1 discloses a vehicle steering wheel equipped with a capacitance-type sensing system. The capacitance-type sensing system is used to detect the presence or absence of a driver's hands on the steering wheel. The capacitance-type sensing system includes a capacitance-type sensing device having a conductive wire at least partially attached to the periphery of the steering wheel and a conductive layer arranged to partially overlap the conductive wire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-521892 Summary of the Invention [Problem to be solved by the invention]

[0004] When the capacitance-type sensing device (electrode structure) disclosed in Patent Document 1 is attached to the rim of a steering wheel, a groove may be formed in the rim and a part of the capacitance-type sensing device may be fitted into the groove to prevent the capacitance-type sensing device from shifting. In this case, it may be desirable to make it easier to prevent the conductive wire pressed into the groove from applying a mechanical load to the conductive layer (conductive cloth).

[0005] Therefore, the present disclosure provides an electrode structure and a grip sensor that can easily prevent the conductive wire from applying mechanical load to the conductive cloth when attached to the rim of a steering wheel. [Means for solving the problem]

[0006] An electrode structure according to one embodiment of the present disclosure comprises a substrate having a marking, a conductive cloth arranged on a first surface of the substrate, and a conductive wire arranged electrically insulated from the conductive cloth on a second surface of the substrate opposite the first surface, wherein the substrate has a first region including the marking that is fitted into a groove provided in the rim when attached to the rim of a steering wheel, and a second region different from the first region that is arranged in a portion of the rim other than the groove, and the wiring density of the conductive wire in the first region is lower than the wiring density of the conductive wire in the second region.

[0007] An electrode structure according to one aspect of the present disclosure includes a substrate, a conductive cloth disposed on a first surface of the substrate, and a conductive wire disposed on a second surface of the substrate opposite the first surface while being electrically insulated from the conductive cloth. When the substrate is attached to a steering wheel rim, the substrate has a first region that fits into a groove formed in the rim and a second region that is disposed in a portion of the rim other than the groove. The wiring density of the conductive wire in the first region is lower than the wiring density of the conductive wire in the second region.

[0008] A grip sensor according to one aspect of the present disclosure includes the electrode structure and a control circuit that detects a change in capacitance formed based on the conductive cloth. [Effects of the Invention]

[0009] In the electrode structure and grip sensor of the present disclosure, when attached to the steering wheel, it is easy to prevent the conductive wire from applying a mechanical load to the conductive cloth. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1A is a diagram showing an example of a vehicle interior in which a grip sensor according to an embodiment is arranged. [Figure 1B] FIG. 1B is a front view showing an example of a steering wheel rim. [Figure 2] FIG. 2 is a diagram showing an example of how to wind the electrode structure around a rim in the embodiment. [Figure 3A] FIG. 3A is a rear view showing an example of a grip sensor according to an embodiment. [Figure 3B] FIG. 3B is a cross-sectional view showing an example of an electrode structure according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing an example of a rim to which an electrode structure is attached, taken along line IV-IV in FIG. 1A. [Figure 5A] FIG. 5A is a schematic diagram showing a main part of an electrode structure according to an embodiment. [Figure 5B] FIG. 5B is a cross-sectional view of a main part of the electrode structure taken along line VB-VB in FIG. 5A. [Figure 6] FIG. 6 is a rear view showing an electrode structure of a comparative example. [Figure 7A] FIG. 7A is a schematic diagram showing a main part of an electrode structure of a comparative example. [Figure 7B] FIG. 7B is a cross-sectional view of a main part of the electrode structure taken along line VIIB-VIIB in FIG. 7A. [Figure 8] FIG. 8 is a schematic diagram showing a main part of an electrode structure according to a modified example of the embodiment. [Figure 9] FIG. 9 is a schematic diagram showing the relationship between the conductive wires in the fourth region and the conductive wires in the second region in the embodiment. [Figure 10] FIG. 10 is a schematic diagram showing the relationship between the conductive wires in the fourth region and the conductive wires in the third region in a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An electrode structure according to one aspect of the present disclosure includes a substrate, a conductive cloth disposed on a first surface of the substrate, and a conductive wire disposed on a second surface of the substrate opposite the first surface while being electrically insulated from the conductive cloth. When the substrate is attached to a steering wheel rim, the substrate has a first region that fits into a groove formed in the rim and a second region that is disposed in a portion of the rim other than the groove. The wiring density of the conductive wire in the first region is lower than the wiring density of the conductive wire in the second region.

[0012] This reduces the number of conductive wires inside the groove when the electrode structure is attached to the steering wheel rim, making it less likely that the conductive wires will compress the conductive cloth between the groove and the surface layer, which makes it easier to prevent the conductive wires from applying mechanical load to the conductive cloth.

[0013] In another aspect of the electrode structure of the present disclosure, the first region further includes a third region located on the outer periphery of the rim when the base is attached to the rim, and a fourth region located on the inner periphery of the rim, and the wiring density of the conductive wires in the third region is lower than the wiring density of the conductive wires in the fourth region.

[0014] This allows the number of conductive wires inside the grooves to be further reduced in areas where the conductive cloth tends to be arranged in a relatively concentrated manner, thereby further reducing the mechanical load that the conductive wires impose on the conductive cloth.

[0015] In an electrode structure according to another aspect of the present disclosure, the third region includes a vertex on the front side of the rim and a vertex on the rear side of the rim when the substrate is attached to the rim.

[0016] This further reduces the number of conductive wires inside the grooves in the area that faces most of the palm of the driver's hand gripping the rim and where the conductive cloth tends to be concentrated, thereby further reducing the mechanical load that the conductive wires impose on the conductive cloth.

[0017] In an electrode structure according to another aspect of the present disclosure, when the substrate is attached to the rim, the conductive cloths located on both sides of the groove are connected in the third region and are not connected in the fourth region.

[0018] According to this, when the portion of the base material corresponding to the fourth region is fitted into the groove of the steering wheel rim, there is no conductive cloth to which the conductive wire would apply a mechanical load, and therefore, even if the conductive wire were present inside the groove, the conductive cloth would not be compressed by the conductive wire.

[0019] In an electrode structure according to another aspect of the present disclosure, the conductive wire passes through the fourth region and is folded back in the second region so as not to pass through the third region.

[0020] According to this, in the groove, at the portion where the portion of the base material corresponding to the third region is fitted, the conductive wire is not present in the groove, and therefore no mechanical load is generated on the conductive cloth by the conductive wire.

[0021] In an electrode structure according to another aspect of the present disclosure, the conductive wire is grounded, and the number of the conductive wires present in the first region is one.

[0022] This makes it easier to prevent the conductive wire from exerting a mechanical load on the conductive cloth.

[0023] A grip sensor according to one aspect of the present disclosure includes the electrode structure and a control circuit that detects a change in capacitance formed based on the conductive cloth.

[0024] This makes it easy to reduce the number of conductive wires inside the groove when the electrode structure is attached to the steering wheel rim, and therefore makes it easy to prevent the conductive wires from compressing the conductive cloth between the conductive wires and the surface layer in the groove, making it easy to prevent the conductive wires from applying mechanical load to the conductive cloth.

[0025] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0026] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in independent claims are described as optional components.

[0027] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Furthermore, the same components are assigned the same reference numerals in each figure. Furthermore, expressions such as "approximately T-shaped" are used in the following embodiments. For example, "approximately T-shaped" does not only mean that it is completely T-shaped, but also means that it is substantially T-shaped, that is, it includes an error of, for example, a few percent. Furthermore, "approximately T-shaped" means that it is T-shaped within the range in which the effects of the present disclosure can be achieved. The same applies to other expressions using "approximately."

[0028] In the following embodiments, the longitudinal direction of the electrode structure is defined as the Y-axis direction, and the direction perpendicular to the Y-axis direction in a plane parallel to the electrode structure is defined as the X-axis direction. In the Y-axis direction, one end of the electrode structure (the left end in FIG. 2) is defined as the negative side, and the other end (the right end in FIG. 2) is defined as the positive side. Similarly, in the X-axis direction, one end of the electrode structure (the lower end in FIG. 2) is defined as the negative side, and the other end (the upper end in FIG. 2) is defined as the positive side. Furthermore, the direction perpendicular to the surface of the electrode structure is defined as the Z-axis direction. In addition, one side of the Z-axis direction (the far side of the paper in FIG. 2) is defined as the negative side, and the other side of the Z-axis direction (the near side of the paper in FIG. 2) is defined as the positive side.

[0029] (Embodiment) <Configuration: Grip sensor 100> 1A is a diagram showing an example of a cabin of a vehicle 1 in which a grip sensor 100 according to an embodiment is arranged. FIG. 1B is a front view showing an example of a rim 31 of a steering wheel 3.

[0030] 1A, a vehicle 1 includes a steering wheel 3, a speaker, and a display device such as a liquid crystal display. The speaker and the display device are configured as, for example, an attention-calling device.

[0031] The steering wheel 3 applies a steering angle to the steered wheels of the vehicle 1. The steering wheel 3 has a rim 31, approximately T-shaped spokes 32 formed integrally with the inner circumferential surface of the rim 31, and a horn switch cover (not shown) that covers a horn switch (not shown) located in the center of the spokes 32.

[0032] 1B, the rim 31 has a plurality of grooves 31b (four in FIG. 1B). The plurality of grooves 31b are formed by reducing the diameter of the rim 31 at corresponding locations. The plurality of grooves 31b are provided in the rim 31 at intervals along the circumferential direction of the rim 31 in a plan view (when the rim 31 is viewed from the front).

[0033] The grip sensor 100 is a capacitance-type sensor that detects gripping of the steering wheel 3 by the hands, and is provided on the steering wheel 3 of the vehicle 1. Specifically, the grip sensor 100 includes an electrode structure 110 attached to the rim 31 of the steering wheel 3, a control circuit 140 that detects gripping based on a signal from the electrode structure 110, and a harness 130 that electrically connects the electrode structure 110 to the control circuit 140. The control circuit 140 is embedded in, for example, the spokes 32. The grip sensor 100 detects gripping of the rim 31 of the steering wheel 3.

[0034] [Electrode structure 110] The electrode structure 110 has at least one electrode. The capacitance of this electrode changes depending on whether the driver (user) of the vehicle 1 is gripping the rim 31 of the steering wheel 3. Specifically, the electrode structure 110 detects whether the user's hand is touching the steering wheel 3 by detecting a change in the capacitance between the user's hand and the electrode structure 110 (conductive cloth 112, described later). When the user's hand is away from the steering wheel 3, the electrode structure 110 detects the capacitance between the core metal 31a (see FIG. 4 ) of the rim 31 and the conductive cloth 112. When the user's hand approaches or touches the steering wheel 3, capacitance is formed between the user's hand and the conductive cloth 112, causing a change in the capacitance. If the detected capacitance is equal to or greater than a specified value, it can be determined that the user's hand is touching or gripping the steering wheel 3.

[0035] FIG. 2 is a diagram showing an example of how the electrode structure 110 of the grip sensor 100 according to the embodiment is wound around the rim 31. In FIG.

[0036] 1A and 2, the electrode structure 110 serving as a steering sheet is a long, sheet-like structure that is elastic, flexible, and ductile overall. The electrode structure 110 is attached to the rim 31 of the steering wheel 3. At this time, the electrode structure 110 is wrapped around the rim 31 so that the electrode structure 110 forms a loop. The ends Ea and Eb of the electrode structure 110 are arranged so as to substantially face each other.

[0037] Here, the electrode structure 110 is stretched when it is wound around the rim 31. Therefore, as described above, the electrode structure 110 has elasticity, flexibility, and ductility, and is stretched as a whole by, for example, about 10% or more.

[0038] Furthermore, when winding the electrode structure 110 around the rim 31, the electrode structure 110 is pushed into each of the plurality of grooves 31 b, so that a portion of the electrode structure 110 is fitted into each of the plurality of grooves 31 b. This prevents the electrode structure 110 from shifting in the circumferential direction of the rim 31 in a plan view.

[0039] Fig. 3A is a rear view showing an example of grip sensor 100 according to the embodiment. Fig. 3B is a cross-sectional view showing an example of electrode structure 110 according to the embodiment. Fig. 4 is a cross-sectional view showing an example of rim 31 to which electrode structure 110 is attached, taken along line IV-IV in Fig. 1A.

[0040] As shown in Figures 3A, 3B, and 4, the electrode structure 110 includes a substrate 111, a conductive cloth 112, an adhesive layer 113, a conductive wire 114, a surface layer 115, a connection terminal 121, and an electric wire 122.

[0041] [Base material 111] The base material 111 is a nonwoven fabric formed into a long sheet shape using a material that has elasticity, flexibility, and ductility. For example, the base material 111 is made of a synthetic resin such as polyethylene (PE) or polyethylene terephthalate (PET). The base material 111 is formed according to the shape and size of the rim 31.

[0042] The base material 111 has a first surface 111a and a second surface 111b. The conductive cloth 112 is disposed on the first surface 111a via an adhesive layer 113, and the conductive wire 114 is disposed on the second surface 111b. In other words, the base material 111 is sandwiched between the conductive cloth 112 and the conductive wire 114. The first surface 111a is an example of one surface of the base material 111, and the second surface 111b is an example of the surface opposite to the one surface of the base material 111. When the electrode structure 110 is wound around the rim 31, the base material 111 is fixed to the rim 31 in a tensioned state, sandwiching the conductive wire 114 between them. When the base material 111 is fixed to the rim 31, the second surface 111b is disposed facing the rim 31 of the steering wheel 3.

[0043] A plurality of (three in FIG. 3A) substantially semicircular notches 111c are provided on both widthwise edges of the base material 111. The portion of the base material 111 sandwiched between the two notches 111c along the widthwise direction is fitted into a groove 31b of the rim 31. This portion corresponds to a first region A1 (see FIG. 5A) described below. Furthermore, the portion of the base material 111 where no notches 111c are provided is wrapped around the rim 31. This portion corresponds to a second region A2 (see FIG. 5A) described below.

[0044] In this embodiment, there are three areas (first areas A1) sandwiched between two notches 111c along the width direction of the base material 111. Therefore, these three areas are fitted into three of the four grooves 31b of the rim 31. Note that both ends Ea and Eb of the electrode structure 110 are fitted into the remaining groove 31b.

[0045] The base material 111 may be divided into a plurality of parts, in which case the conductive cloth 112 is formed on each of the plurality of parts.

[0046] [Conductive Fabric 112] The conductive cloth 112 is arranged via an adhesive layer 113 attached to the first surface 111a of the base material 111. In other words, the conductive cloth 112 is arranged on the back surface of the surface layer portion 115 and on the first surface 111a of the base material 111, and is sandwiched between the surface layer portion 115 and the base material 111. The conductive cloth 112 is adhered to the back surface of the surface layer portion 115 with the adhesive layer 113, and is also adhered to the first surface 111a of the base material 111 with the adhesive layer 113, and is fixed to the base material 111. The first surface 111a of the base material 111 is the surface that is arranged facing the surface layer portion 115.

[0047] Only one or more conductive cloths 112 may be arranged on the first surface 111a of the substrate 111. As shown in FIG. 3A, the embodiment illustrates a case where the electrode structure 110 has two conductive cloths 112 and two conductive wires 114.

[0048] [Adhesive layer 113] The adhesive layer 113 is attached to the first surface 111a of the base material 111, and fixes the conductive cloth 112 to the first surface 111a side of the base material 111. The adhesive layer 113 is made of, for example, an adhesive, double-sided tape, or the like. The adhesive layer 113 may also be a double-sided tape without a base material. In this case, the adhesive layer 113 is made of only an adhesive.

[0049] An adhesive layer 113 is also formed on the back surface of the surface layer portion 115, and this adhesive layer 113 fixes the surface layer portion 115 to the conductive cloth 112. This adhesive layer 113 is also made of, for example, an adhesive, double-sided tape, etc., but it may also be a substrate-less double-sided tape, or may be made of only an adhesive.

[0050] [Conductive Wire 114] The conductive wire 114 is made of a metal wire (conductive wire) such as a copper wire sewn to the base material 111. The conductive wire 114 is a ground electrode that is electrically connected to the control circuit unit 140 via an electric wire 114a or the like and is grounded. Specifically, the conductive wire 114 is electrically connected to an electric wire 114a that is different from the electric wire 122 while being electrically insulated from the conductive cloth 112, and is electrically connected to the control circuit unit 140 via the electric wire 114a.

[0051] In the embodiment, the conductive wire 114 is, for example, a resin-coated metal wire and is used as a heater element. That is, the surface of the conductive wire 114 is electrically insulated. When a current flows through the conductive wire 114 by the control circuit unit 140, the conductive wire 114 generates heat. This heat allows the conductive wire 114 to heat the electrode structure 110, which in turn heats the rim 31 of the steering wheel 3. This allows the driver of the vehicle 1 to comfortably grip the rim 31 even when the interior of the vehicle is cold.

[0052] The conductive wires 114 are disposed on a second surface 111b opposite to the first surface 111a of the base material 111. Specifically, the conductive wires 114 are sewn to form a zigzag pattern on the second surface 111b opposite to the first surface 111a of the base material 111. In reality, the bent portions of both of the two conductive wires 114 are curved.

[0053] As already mentioned, in this embodiment, there are two conductive wires 114. Both ends of one (left side in FIG. 3A) of the two pairs of connection terminals 121 are electrically and mechanically connected to one (left side in FIG. 3A) of the pair of connection terminals 121. Also, both ends of the other (right side in FIG. 3A) of the conductive wire 114 are electrically and mechanically connected to the other (right side in FIG. 3A) of the pair of connection terminals 121.

[0054] With the electrode structure 110 wound around the rim 31, the conductive wire 114 is placed on the surface of the rim 31 and is bonded to the surface of the rim 31 with an adhesive (not shown). In other words, the conductive wire 114 is sandwiched between the rim 31 and the substrate 111.

[0055] The wiring structure of the conductive wire 114 will be described in detail below with reference to Figures 5A and 5B. Figure 5A is a schematic diagram showing a main part of the electrode structure 110 in this embodiment. Figure 5B is a cross-sectional view of the main part of the electrode structure 110 taken along line VB-VB in Figure 5A. In Figure 5B, the adhesive layer 113 and the surface layer 115 are not shown.

[0056] 5A, the base material 111 is roughly divided into a first region A1 and a second region A2. The first region A1 is a region that fits into a groove 31b provided in the rim 31 when the electrode structure 110 is attached to the rim 31 of the steering wheel 3. In the embodiment, the first region A1 corresponds to a portion of the base material 111 sandwiched between two notches 111c along the width direction. The second region A2 is a region that is disposed in a portion of the rim 31 other than the groove 31b when the electrode structure 110 is attached to the rim 31 of the steering wheel 3.

[0057] The conductive wires 114 are arranged on the base material 111 so that the wiring density differs between the first region A1 and the second region A2. Specifically, the conductive wires 114 are arranged on the base material 111 so that the wiring density of the conductive wires 114 in the first region A1 is lower than the wiring density of the conductive wires 114 in the second region A2.

[0058] Here, the wiring density is expressed as the area of ​​the conductive wires 114 per unit area of ​​the substrate 111 when viewed from the thickness direction (Z-axis direction). In other words, the wiring density is expressed as the number of conductive wires 114 present in an area per unit area of ​​the substrate 111 when viewed from the thickness direction. In other words, the higher the wiring density, the greater the number of conductive wires 114 present in the area, and the lower the wiring density, the fewer the number of conductive wires 114 present in the area.

[0059] The number of conductive wires 114 referred to here is the number of conductive wires 114 that intersect with an imaginary line along the width direction (X-axis direction) of the substrate 111 in an area per unit area of ​​the substrate 111. Therefore, the number of conductive wires 114 referred to here is not necessarily the number of conductive wires 114.

[0060] 5A, the number of conductive wires 114 present in each of the second regions A2 on both the left and right sides of the first region A1 is six, while the number of conductive wires 114 present in the first region A1 is two. In other words, the wiring density of the conductive wires 114 in the first region A1 is lower than the wiring density of the conductive wires 114 in the second region A2.

[0061] Moreover, in this embodiment, the base material 111 further has a third region A3 and a fourth region A4. The third region A3 is a region that is located on the outer periphery of the rim 31 when the base material 111 is attached to the rim 31. In other words, the third region A3 is a region that faces the palm of the driver of the vehicle 1 who grips the rim 31 when the base material 111 is attached to the rim 31. In yet another way, the third region A3 is a region that mainly includes a portion that is stretched and under tension when the base material 111 is attached to the rim 31.

[0062] The fourth region A4 is an area located on the inner periphery of the rim 31 when the base material 111 is attached to the rim 31. In other words, the fourth region A4 is an area that faces the fingertips of the driver of the vehicle 1 who grips the rim 31 when the base material 111 is attached to the rim 31. In other words, the fourth region A4 is an area that mainly includes a portion that is in a contracted state and is not under tension when the base material 111 is attached to the rim 31.

[0063] 5A, the third region A3 is a region that includes the apex 31c on the front side of the rim 31 and the apex 31d on the rear side of the rim 31 when the base material 111 is attached to the rim 31. When the driver of the vehicle 1 is gripping the rim 31, the front of the rim 31 is the direction from the driver toward the rim 31, and the rear of the rim 31 is the direction from the rim 31 toward the driver. In other words, the front of the rim 31 is the direction in which the vehicle 1 moves forward, and the rear of the rim 31 is the direction in which the vehicle 1 moves backward.

[0064] The third region A3 may be any region located on the outer periphery of the rim 31 when the base material 111 is attached to the rim 31, and may have a dimension in the width direction (X-axis direction) that is several tens of percent shorter or longer than the front peak 31c and rear peak 31d of the rim 31. In other words, the third region A3 may or may not be a region that includes the front peak 31c and rear peak 31d of the rim 31.

[0065] Furthermore, the conductive wires 114 are arranged on the base material 111 so that the wiring density differs between the third region A3 and the fourth region A4. Specifically, the conductive wires 114 are arranged on the base material 111 so that the wiring density of the conductive wires 114 in the third region A3 is lower than the wiring density of the conductive wires 114 in the fourth region A4.

[0066] 5A, the number of conductive wires 114 present in each of the fourth regions A4 on both the upper and lower sides of the third region A3 is one, while the number of conductive wires 114 present in the third region A3 is zero. In other words, the wiring density of the conductive wires 114 in the third region A3 is lower than the wiring density of the conductive wires 114 in the fourth region A4.

[0067] Therefore, in the embodiment, when the portion of the base material 111 corresponding to the first region A1 is fitted into the groove 31b of the rim 31 of the steering wheel 3, the number of conductive wires 114 present in the groove 31b is two. In particular, in the portion of the groove 31b where the portion of the base material 111 corresponding to the third region A3 is fitted, the number of conductive wires 114 present in the groove 31b is zero, as shown in FIG. 5B .

[0068] In order to realize the wiring structure of the conductive wire 114 as described above, the conductive wire 114 is arranged on the substrate 111 as shown in Figures 3A and 5A. That is, in this embodiment, the conductive wire 114 forms a closed loop by electrically and mechanically connecting both ends to a pair of connection terminals 121. The conductive wire 114 passes through (crosses) the fourth region A4 and is folded back in the second region A2 so as not to pass through the third region A3.

[0069] [Surface layer 115] The surface layer 115 is the part that comes into contact with the hand and forms the outer periphery of the grip sensor 100. In other words, the surface layer 115 is the part that comes into direct contact with the user's hand when the user grips the rim 31. The surface layer 115 is made of leather, wood, resin, or the like, and is leather in this embodiment.

[0070] [Connection terminal 121 and electric wire 122] The connection terminal 121 is a ring-shaped or round crimp terminal, and is fastened and fixed to the base material 111, the conductive cloth 112, etc. by a fastening member.

[0071] One end of the electric wire 122 is electrically and mechanically connected to the corresponding connection terminal 121 in a one-to-one relationship, and the other end is electrically connected to the control circuit unit 140. The electric wire 122 is a cable for electrically connecting the conductive cloth 112 to the control circuit unit 140, and is, for example, an insulating-coated copper wire. Furthermore, the electric wire 122 is fixed in a state electrically connected to the conductive cloth 112 by a fastening member (not shown), such as a rivet.

[0072] [Control circuit section 140] The control circuit unit 140 is embedded in, for example, the spokes 32. The control circuit unit 140 is electrically connected to the conductive wire 114 and the conductive cloth 112, and detects contact of the steering wheel 3 with the hand of the driver (user 9) of the vehicle 1 based on a signal transmitted from the conductive cloth 112. The control circuit unit 140 measures whether the user's hand is in contact with the surface layer 115. The control circuit unit 140 detects whether the user's hand is in contact with the rim 31, that is, detects the contact of the hand, and the contact position of the hand, etc.

[0073] The control circuit section 140 includes a control circuit and a power supply circuit.

[0074] The control circuit has a sensor circuit that detects contact between the human body and the steering wheel 3 through the conductive cloth 112. The control circuit is electrically connected to each conductive cloth 112, and detects contact between the human body and the steering wheel 3 through the conductive cloth 112.

[0075] Specifically, the control circuit passes an AC current through the two conductive cloths 112 via the electric wires 122, i.e., applies a measurement potential to the conductive cloths 112. The control circuit is electrically connected to the two conductive cloths 112 via the electric wires 122. When a hand touches the surface layer 115 of the rim 31, the capacitance of the conductive cloth 112 corresponding to the contact point changes, and the control circuit measures the change in capacitance in the conductive cloth 112 based on the current value (measurement potential) of the current flowing through the conductive cloth 112. In other words, the control circuit (control circuit unit 140) detects a change in capacitance formed based on the conductive cloth 112. In this way, the control circuit can detect whether or not a hand has touched the steering wheel 3 from a signal indicating a change in capacitance output from the conductive cloth 112.

[0076] The power supply circuit is electrically connected to the control circuit via the electric wire 122 and is controlled by the control circuit. The power supply circuit is also electrically connected to the conductive wire 114 via the electric wire 122 etc. The power supply circuit applies a measurement potential to the conductive cloth 112 via the control circuit.

[0077] The power supply circuit may be controlled by a control circuit so that a direct current flows through the conductive wire 114. In other words, the conductive wire 114 may function as a heater by passing a direct current through it. In this case, since only a direct current flows through the conductive wire 114, the conductive wire 114 is considered to be grounded from the perspective of the alternating current flowing through the conductive cloth 112.

[0078] <Comparison> The advantages of the electrode structure 110 according to the embodiment will be described below, along with a comparison with an electrode structure 200 of a comparative example. FIG. 6 is a rear view showing the electrode structure 200 of the comparative example. FIG. 7A is a schematic diagram showing a main part of the electrode structure 200 of the comparative example. FIG. 7B is a cross-sectional view of a main part of the electrode structure 200 taken along line VIIB-VIIB in FIG. 7A. In FIG. 7B, the adhesive layer 113 and the surface layer portion 115 are not shown.

[0079] The electrode structure 200 of the comparative example differs from the electrode structure 110 of the embodiment in that the wiring density of the conductive wires 114 in the first region A1 is substantially the same as the wiring density of the conductive wires 114 in the second region A2. Specifically, as shown in Figures 6 and 7A, in the electrode structure 200 of the comparative example, the number of conductive wires 114 present in the first region A1 is six, and the number of conductive wires 114 present in each of the second regions A2 on both the left and right sides of the first region A1 is six. In other words, in the electrode structure 200 of the comparative example, no effort is made to reduce the wiring density of the conductive wires 114 in the first region A1, and the conductive wires 114 are arranged on the substrate 111 by simply folding back at both the left and right ends of the conductive cloth 112.

[0080] 7B, in the electrode structure 200 of the comparative example, when attached to the rim 31 of the steering wheel 3, a larger amount of the conductive wire 114 fits inside the groove 31b than in the electrode structure 110 of the embodiment. Therefore, in the electrode structure 200 of the comparative example, the conductive wire 114 bent inside the groove 31b may compress the conductive cloth 112 between the electrode structure 200 of the comparative example and the surface layer portion 115.

[0081] On the other hand, in the electrode structure 110 of the embodiment, the conductive wires 114 are arranged on the substrate 111 so that the wiring density of the conductive wires 114 in the first region A1 is lower than the wiring density of the conductive wires 114 in the second region A2. Therefore, in the electrode structure 110 of the embodiment, when attached to the rim 31 of the steering wheel 3, the number of conductive wires 114 that fit inside the grooves 31b is smaller than in the electrode structure 200 of the comparative example. Therefore, in the electrode structure 110 of the embodiment, the conductive wires 114 are less likely to press against the conductive cloth 112 between the surface layer portion 115 in the grooves 31b compared to the electrode structure 200 of the comparative example, and therefore mechanical load is less likely to be applied to the conductive cloth 112.

[0082] In particular, in the electrode structure 110 of the embodiment, the conductive wires 114 are arranged on the base material 111 so that the wiring density of the conductive wires 114 in the third region A3 is lower than the wiring density of the conductive wires 114 in the fourth region A4. Here, the third region A3 is a region where the conductive cloth 112 is arranged more concentratedly than the fourth region A4. Therefore, by making the wiring density of the conductive wires 114 in the third region A3 lower than the wiring density of the conductive wires 114 in the fourth region A4, mechanical load is further reduced on the conductive cloth 112. In the example shown in FIG. 5B , in the region of the groove 31b where the portion of the base material 111 corresponding to the third region A3 is fitted, the conductive wires 114 are not present in the groove 31b, and therefore no mechanical load is generated on the conductive cloth 112 by the conductive wires 114.

[0083] <Action and effect> As described above, the electrode structure 110 in this embodiment includes the substrate 111, the conductive cloth 112 arranged on the first surface 111a of the substrate 111, and the conductive wire 114 arranged on the second surface 111b of the substrate 111 opposite the first surface 111a and in a state where it is electrically insulated from the conductive cloth 112. When the substrate 111 is attached to the rim 31 of the steering wheel 3, the substrate 111 has a first region A1 that is fitted into a groove 31b formed in the rim 31, and a second region A2 that is arranged in a portion of the rim 31 other than the groove 31b. The wiring density of the conductive wire 114 in the first region A1 is lower than the wiring density of the conductive wire 114 in the second region A2.

[0084] This makes it possible to reduce the number of conductive wires 114 present inside the grooves 31b when the electrode structure 110 is attached to the rim 31 of the steering wheel 3. Therefore, the conductive wires 114 are less likely to press against the conductive cloth 112 between themselves and the surface layer portion 115 in the grooves 31b, which makes it easier to prevent the conductive wires 114 from applying a mechanical load to the conductive cloth 112.

[0085] Furthermore, in the electrode structure 110 of the embodiment, the first region A1 further includes a third region A3 located on the outer periphery of the rim 31 and a fourth region A4 located on the inner periphery of the rim 31 when the base material 111 is attached to the rim 31. The wiring density of the conductive wires 114 in the third region A3 is lower than the wiring density of the conductive wires 114 in the fourth region A4.

[0086] This further reduces the number of conductive wires 114 present inside the grooves 31b in areas where the conductive cloth 112 tends to be arranged in a relatively concentrated manner, thereby further reducing the mechanical load that the conductive wires 114 impose on the conductive cloth 112.

[0087] In the electrode structure 110 of the embodiment, the third region A3 includes the apex 31c on the front side of the rim 31 and the apex 31d on the rear side of the rim 31 when the base material 111 is attached to the rim 31.

[0088] This makes it possible to further reduce the number of conductive wires 114 present inside the grooves 31b in an area that faces most of the palm of the driver of the vehicle 1 gripping the rim 31 and where the conductive cloth 112 is likely to be arranged in a relatively concentrated manner. Therefore, it is easier to further prevent the conductive wires 114 from applying a mechanical load to the conductive cloth 112.

[0089] In the electrode structure 110 according to the embodiment, the conductive wire 114 passes through the fourth region A4 and is folded back in the second region A2 so as not to pass through the third region A3.

[0090] According to this, in the portion of groove 31b where the portion corresponding to third region A3 of substrate 111 is fitted, conductive wire 114 is not present in groove 31b, so no mechanical load is generated on conductive cloth 112 by conductive wire 114.

[0091] The grip sensor 100 according to the embodiment also includes the electrode structure 110 and a control circuit unit 140 that detects a change in capacitance formed based on the conductive cloth 112.

[0092] This makes it easy to reduce the number of conductive wires 114 present inside the grooves 31b when the electrode structure 110 is attached to the rim 31 of the steering wheel 3. Therefore, the conductive wires 114 are less likely to press against the conductive cloth 112 between themselves and the surface layer portion 115 in the grooves 31b, making it easy to prevent the conductive wires 114 from applying a mechanical load to the conductive cloth 112.

[0093] (Modification of the embodiment) In the following, the basic configuration of the electrode structure 110a of this modified example is similar to the basic configuration of the electrode structure 110 according to the embodiment, and therefore, a description of the basic configuration of the electrode structure 110a of this modified example will be omitted where appropriate. As shown in Fig. 8, the electrode structure 110a of this modified example differs from the electrode structure 110 of the embodiment in that the configuration of the conductive cloth 112 is different. Fig. 8 is a schematic diagram showing the main parts of the electrode structure 110a of the modified example of the embodiment.

[0094] Specifically, the conductive cloth 112 has a smaller width dimension (X-axis direction) in the first region A1 than in the second region A2. When the base material 111 is viewed in the thickness direction (Z-axis direction), the conductive cloth 112 is present only in the third region A3 of the first region A1, and is not present in the fourth region A4 of the first region A1.

[0095] In other words, in the electrode structure 110a in the modified embodiment, when the substrate 111 is attached to the rim 31, the conductive cloth 112 located on both sides of the groove 31b is connected in the third region A3 but is not connected in the fourth region A4.

[0096] According to this, when the portion of the base material 111 corresponding to the fourth region A4 is fitted into the groove 31b of the rim 31 of the steering wheel 3, the conductive cloth 112 to which the conductive wire 114 applies a mechanical load is not present. Therefore, even if the conductive wire 114 is present inside the groove 31b, the conductive cloth 112 is unlikely to be compressed by the conductive wire 114.

[0097] (Other variations) While the electrode structures 110, 110a according to the present disclosure have been described above based on the above-mentioned embodiments and modifications, the present disclosure is not limited to these embodiments and modifications. As long as they do not deviate from the spirit of the present disclosure, various modifications conceivable by those skilled in the art may also be included within the scope of the present disclosure.

[0098] For example, in the electrode structures 110 and 110a in the embodiment and the modified example, the steering wheel 3 has two conductive cloths 112 and two conductive wires 114, but may have one or three or more conductive cloths 112 and one or three or more conductive wires 114. For example, four conductive cloths 112 may be arranged on one base material 111 to increase the grip position detection resolution of the steering wheel 3, while the same base material may have only one conductive wire 114 to simplify the configuration of the conductive wire 114. Furthermore, the number of conductive cloths 112 and the number of conductive wires 114 do not necessarily have to be the same.

[0099] In the electrode structures 110 and 110a according to the embodiment and the modified examples, the conductive wires 114 are resin-coated metal wires, but the present invention is not limited to such a configuration. For example, the conductive wires 114 may be resin wires plated with metal.

[0100] Furthermore, in the electrode structures 110 and 110a according to the embodiment and the modified examples, the conductive wire 114 is used as a heater element capable of detecting a noise signal in response to a signal detected by the conductive cloth 112. However, the conductive wire 114 may also be used for other purposes. For example, the conductive wire 114 may be used as a disturbance noise detection electrode. That is, the conductive wire 114 may be a disturbance noise detection electrode for detecting a disturbance noise in response to an output signal detected by the conductive cloth 112. In this case, the control circuit 140 acquires a disturbance noise signal from the conductive wire 114, which serves as the disturbance noise detection electrode. The control circuit 140 may then correct the output signal of the conductive cloth 112, for example, by subtracting the value indicated by the disturbance noise signal from the value indicated by the output signal of the conductive cloth 112. As a result, the control circuit 140 can more accurately detect the grip of the rim 31 by the hand.

[0101] Furthermore, in the electrode structures 110, 110a in the embodiment and the modified examples, when the conductive wire 114 is used as a heater element or a disturbance noise detection electrode, the conductive wire 114 is directly connected to the control circuit unit 140, but the present invention is not limited to such a configuration. That is, the heater element or the disturbance noise detection electrode may be connected to an external circuit such as the control circuit unit 140 via the electrode structure 110, 110a.

[0102] Furthermore, in the electrode structures 110 and 110a according to the embodiment and the modified examples, the conductive wire 114 is not limited to a configuration having a heater function, and may be configured to be simply grounded without passing a direct current. That is, the conductive wire 114 may function as a shield electrode that blocks disturbance noise. In this case, the conductive wire 114 does not need to form a closed loop by electrically and mechanically connecting both ends to a pair of connection terminals 121. That is, instead of a single conductive wire 114, multiple conductive wires 114 may be arranged on the substrate 111, and these conductive wires 114 may be grounded.

[0103] Furthermore, the electrode structures 110, 110a in the embodiment and the modified examples are configured by arranging the conductive cloth 112 and the conductive wire 114 on one substrate 111, but are not limited to this configuration. For example, the electrode structures 110, 110a may be configured by joining together a first substrate on which the conductive cloth 112 is arranged and a second substrate on which the conductive wire 114 is arranged. In this case, the first substrate and the second substrate correspond to the substrate 111.

[0104] Furthermore, when the conductive wire 114 is grounded and used as a shield electrode, there is no need to form a closed loop, so the number of conductive wires 114 present in the first region A1 can be one. That is, in the electrode structures 110 and 110a of the embodiment and the modified examples, the conductive wire may be grounded. The number of conductive wires 114 present in the first region A1 may be one.

[0105] This makes it easier to prevent the conductive wire 114 from applying a mechanical load to the conductive cloth 112.

[0106] 9, the conductive wires 114 in the fourth region A4 may be arranged closer to being parallel to the longitudinal direction (Y-axis direction) of the substrate 111 than the conductive wires 114 in the second region A2. Fig. 9 is a schematic diagram showing the relationship between the conductive wires in the fourth region A4 and the conductive wires in the second region A2 in the embodiment.

[0107] Specifically, in the electrode structure 110b shown in FIG. 9, the conductive wires 114 in the fourth region A4 and the conductive wires 114 in the second region A2 are arranged in a wavy shape when the substrate 111 is viewed from the thickness direction (Z-axis direction).

[0108] In the electrode structure 110b shown in FIG. 9, in the width direction (X-axis direction) of the base material 111, the amplitude W2 of the conductive wires 114 in the fourth region A4 is smaller than the amplitude W1 of the conductive wires 114 in the second region A2.

[0109] More specifically, (1) in the width direction (X-axis direction) of the substrate 111, the length between the maximum value B1 and the minimum value B2 of the position of one conductive wire 114 in the fourth region A4 (i.e., amplitude W2 = B1 - B2) is longer than the length, and (2) in the width direction (X-axis direction) of the substrate 111, the length between the maximum value C1 and the minimum value C2 of the position of one conductive wire 114 in the second region A2 (i.e., amplitude W1 = C1 - C2).

[0110] Here, the position of the conductive wire 114 in the width direction (X-axis direction) of the substrate 111 is defined as decreasing toward the bottom of the paper and increasing toward the top of the paper. The same applies to Fig. 10 described later.

[0111] The fourth region A4 is a region that mainly includes a portion that is in a contracted state and is not under tension when the base material 111 is attached to the rim 31. Therefore, the conductive wire 114 in the fourth region A4 is arranged so as to be closer to parallel to the longitudinal direction (Y-axis direction) of the base material 111 than the conductive wire 114 in the second region A2, thereby reducing excess conductive wire 114 in the fourth region A4. As a result, the excess conductive wire 114 in the fourth region A4 is less likely to protrude from the base material 111, improving the appearance. Furthermore, since the excess conductive wire 114 in the fourth region A4 is less likely to protrude from the base material 111, it is less likely to affect the tactile sensation when the user's hand grips the rim 31 of the steering wheel 3.

[0112] 10, when conductive wires 114 are also arranged in the third region A3, the conductive wires 114 in the fourth region A4 may be arranged closer to being parallel to the longitudinal direction (Y-axis direction) of the substrate 111 than the conductive wires 114 in the third region A3. Fig. 10 is a schematic diagram showing the relationship between the conductive wires in the fourth region A4 and the conductive wires in the third region A3 in a modified example of the embodiment.

[0113] Specifically, in the electrode structure 110c shown in FIG. 10, the conductive wires 114 in the fourth region A4 and the conductive wires 114 in the third region A3 are arranged in a wavy shape when the substrate 111 is viewed from the thickness direction (Z-axis direction).

[0114] In the electrode structure 110c shown in FIG. 10, in the width direction (X-axis direction) of the base material 111, the amplitude W2 of the conductive wire 114 in the fourth region A4 is smaller than the amplitude W3 of the conductive wire 114 in the third region A3.

[0115] More specifically, (1) in the width direction (X-axis direction) of the substrate 111, the length between the maximum value B1 and the minimum value B2 of the position of one conductive wire 114 in the fourth region A4 (i.e., amplitude W2 = B1 - B2) is longer than the length, and (2) in the width direction (X-axis direction) of the substrate 111, the length between the maximum value D1 and the minimum value D2 of the position of one conductive wire 114 in the third region A3 (i.e., amplitude W3 = D1 - D2).

[0116] Compared to the third region A3, the fourth region A4 is a region that mainly includes a portion that is contracted and therefore not under tension when the substrate 111 is attached to the rim 31. Therefore, the conductive wire 114 in the fourth region A4 is arranged to be closer to parallel to the longitudinal direction (Y-axis direction) of the substrate 111 than the conductive wire 114 in the third region A3, thereby reducing the amount of excess conductive wire 114 in the fourth region A4. As a result, the excess conductive wire 114 in the fourth region A4 is less likely to protrude from the substrate 111, improving the appearance. Furthermore, since the excess conductive wire 114 in the fourth region A4 is less likely to protrude from the substrate 111, it is less likely to affect the tactile sensation when the user's hand grips the rim 31 of the steering wheel 3.

[0117] On the other hand, compared to the fourth region A4, the third region A3 is a region that mainly includes a portion that is under tension when the substrate 111 is attached to the rim 31, and is also a region that is under tension when fitted into the groove 31b of the rim 31. For this reason, the conductive wire 114 in the third region A3 is arranged to be more inclined with respect to the longitudinal direction (Y-axis direction) of the substrate 111 than the conductive wire 114 in the fourth region A4, thereby making it possible to increase the surplus of the conductive wire 114 in the third region A3. As a result, when the substrate 111 is attached to the rim 31, mechanical load is less likely to be applied to the conductive wire 114 arranged in the third region A3.

[0118] The conductive wires 114 in the fourth region A4 may be arranged closer to being parallel to the longitudinal direction (Y-axis direction) of the substrate 111 than the conductive wires 114 in the second region A2 and the conductive wires 114 in the third region A3.

[0119] In addition, this disclosure also includes forms obtained by making various modifications to the above embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the intent of this disclosure. [Industrial Applicability]

[0120] The electrode structure of the present disclosure is applicable to a grip sensor disposed on, for example, a steering wheel of a vehicle. Also, the grip sensor of the present disclosure is applicable as a grip sensor disposed on, for example, a steering wheel of a vehicle. [Explanation of symbols]

[0121] 110,110a,110b,110c electrode structure 111 Base material 111a 1st page 111b 2nd side 112 Conductive cloth 114 Conductive Wire 140 Control circuit section 3 Steering wheel 31 rims 31b Groove 31c Front top 31d Rear top A1 1st area A2 2nd area A3 3rd area A4 4th area B1, C1, D1 Maximum value in the X-axis direction B2, C2, D2 Minimum value in the X-axis direction W1,W2,W3 amplitude

Claims

1. a substrate having a first region configured to fit into a groove in a rim and having a marked first area, and a second region configured to be positioned along a portion of the rim other than the groove and different from the first region; one or more conductive wires disposed on the substrate; the one or more conductive wires are disposed across the first region and the second region; the one or more conductive wires are arranged at a lower wiring density in the first region than in the second region; Electrode structure.

2. The substrate has a notch at a location corresponding to the groove. The electrode structure of claim 1 .

3. the first region further includes a third region and a fourth region disposed adjacent to the third region in a direction perpendicular to the circumferential direction of the rim and corresponding to the notch, the one or more conductive wires are arranged at a lower wiring density in the third region than in the fourth region; The electrode structure according to claim 2 .

4. a portion of the one or more conductive wires passes through the fourth region, and another portion of the one or more conductive wires is folded back in the second region so as not to pass through the third region; The electrode structure according to claim 3 .

5. a portion of the one or more conductive wires is folded back in the second region so as not to pass through the first region; The electrode structure of claim 1 .

6. a control circuit for detecting contact of a user's hand with the rim; The electrode structure according to any one of claims 1 to 5.

7. Equipped with a steering wheel, the rim and the control circuit are included in the steering wheel; The electrode structure according to claim 6 .

8. a substrate having a first region configured to fit into a groove in a rim and having a marked first area, and a second region configured to be positioned along a portion of the rim other than the groove and different from the first region; one or more conductive wires disposed on the substrate; the one or more conductive wires are disposed across the first region and the second region; a number of the one or more conductive wires intersecting a first cross section of the first region is less than a number of the one or more conductive wires intersecting a second cross section of the second region, and the first cross section and the second cross section are perpendicular to a circumferential direction of the rim. Electrode structure.

9. The substrate has a notch at a location corresponding to the groove. The electrode structure of claim 8 .

10. the first region further includes a third region and a fourth region disposed adjacent to the third region in a direction perpendicular to the circumferential direction of the rim and corresponding to the notch, a number of the one or more conductive wires intersecting a third cross section in the third region is less than a number of the one or more conductive wires intersecting a fourth cross section in the fourth region, and the third cross section and the fourth cross section are perpendicular to a circumferential direction of the rim. The electrode structure of claim 9.

11. a portion of the one or more conductive wires passes through the fourth region, and another portion of the one or more conductive wires is folded back in the second region so as not to pass through the third region; The electrode structure of claim 10.

12. a portion of the one or more conductive wires is folded back in the second region so as not to pass through the first region; The electrode structure of claim 8 .

13. a control circuit for detecting contact of a user's hand with the rim; The electrode structure according to any one of claims 8 to 12.

14. Equipped with a steering wheel, the rim and the control circuit are included in the steering wheel; The electrode structure of claim 13.

15. a substrate having a first region configured to fit into a groove in a rim and having a marked first area, and a second region configured to be positioned along a portion of the rim other than the groove and different from the first region; one or more conductive wires disposed on the substrate; a first radial dimension of the rim at the groove is smaller than a second radial dimension of the rim at a portion other than the groove; a number of the one or more conductive wires intersecting a first cross section of the first region is less than a number of the one or more conductive wires intersecting a second cross section of the second region, and the first cross section and the second cross section are perpendicular to a circumferential direction of the rim. Electrode structure.

16. the one or more conductive wires are positioned to straddle the groove when the substrate is attached to the rim. The electrode structure of claim 15.

17. The substrate has a notch at a location corresponding to the groove. The electrode structure of claim 15.

18. the first region further includes a third region and a fourth region disposed adjacent to the third region in a direction perpendicular to the circumferential direction of the rim and corresponding to the notch, a number of the one or more conductive wires intersecting a third cross section in the third region is less than a number of the one or more conductive wires intersecting a fourth cross section in the fourth region, and the third cross section and the fourth cross section are perpendicular to a circumferential direction of the rim.

18. The electrode structure of claim 17.

19. a portion of the one or more conductive wires passes through the fourth region, and another portion of the one or more conductive wires is folded back in the second region so as not to pass through the third region; 20. The electrode structure of claim 18.

20. a portion of the one or more conductive wires is folded back in the second region so as not to pass through the first region; The electrode structure of claim 15.

21. a substrate having a first region configured to fit into a groove in a rim and having a marked first area, and a second region configured to be positioned along a portion of the rim other than the groove and different from the first region; one or more conductive wires disposed on the substrate; a first radial dimension of the rim at the groove is smaller than a second radial dimension of the rim at a portion other than the groove; the one or more conductive wires are arranged at a lower wiring density in the first region than in the second region; Electrode structure.

22. the one or more conductive wires are positioned to straddle the groove when the substrate is attached to the rim.

22. The electrode structure of claim 21.

23. The substrate has a notch at a location corresponding to the groove.

22. The electrode structure of claim 21.

24. the first region further includes a third region and a fourth region disposed adjacent to the third region in a direction perpendicular to the circumferential direction of the rim and corresponding to the notch, a number of the one or more conductive wires intersecting a third cross section in the third region is less than a number of the one or more conductive wires intersecting a fourth cross section in the fourth region, and the third cross section and the fourth cross section are perpendicular to a circumferential direction of the rim.

24. The electrode structure of claim 23.

25. a portion of the one or more conductive wires passes through the fourth region, and another portion of the one or more conductive wires is folded back in the second region so as not to pass through the third region; 25. The electrode structure of claim 24.

26. a portion of the one or more conductive wires is folded back in the second region so as not to pass through the first region; 22. The electrode structure of claim 21.

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