JP2021082573A - Capacitive sensor and method of manufacturing the same - Google Patents

Abstract

To provide a capacitive sensor capable of suppressing a decrease in reliability of the sensing accuracy of a detection electrode, and a method of manufacturing the same.SOLUTION: A capacitive sensor 100 includes: a sheet-like substrate 113; and a capacitance type detection electrode 112 disposed on a surface 113a of the substrate 113. The detection electrode 112 is a conductive fabric made by applying a metal plating on a mesh fabric that is woven of a plurality of warps 132a and a plurality of wefts 132b and has openings 132c each formed by two adjacent warps 132a among the plurality of warps 132a and two adjacent wefts 132b among the plurality of wefts 132b. An area defined by a maximum outside diameter of one warp 132a or one weft 132b in the detection electrode 112 is smaller than an area of an opening space of each of the openings 132c.SELECTED DRAWING: Figure 5

Description

Conventionally, a heater / sensor for a vehicle seat has been proposed (see, for example, Patent Document 1). The heater / sensor comprises a sensing layer that generates a signal for determining the presence of the occupant, contact between the occupant and the components of the vehicle, or both, and a conductive non-woven fabric clamped to the sensing layer.

Japanese Unexamined Patent Publication No. 2018-2076776 Japanese Patent No. 5947919

The seat heater / sensor described in Patent Document 1 and the capacitance sensor for steering described in Patent Document 2 have a problem in the reliability of the detection accuracy of the sensor. For example, when the steering cover is attached to the rim of a vehicle, the non-woven fabric may crack due to tensile stress because the steering cover is pulled and stretched while being wound around the rim. In addition, after the conventional capacitance sensor is wound around the rim, when the user grips the steering wheel, wrinkles may occur on the steering cover, and the non-woven fabric may also bend following the bending of the wrinkles. .. The non-woven fabric has a structure in which fibers are entwined, and cracks may occur. If cracks occur in the non-woven fabric, there is a problem that the resistance value of the non-woven fabric increases.

Therefore, an object of the present disclosure is to provide a capacitance sensor and a method for manufacturing the capacitance sensor, which can suppress a decrease in reliability of the detection accuracy of the detection electrode.

The capacitance sensor according to one aspect of the present disclosure includes a sheet-shaped base material having a front surface and a back surface, and a capacitance type detection electrode arranged on the front surface of the base material, and the detection is performed. The electrode has a plurality of warp yarns which are twisted wires and a plurality of weft yarns which are twisted wires, and is woven by the plurality of warp yarns and the plurality of weft yarns, and two adjacent warp yarns among the plurality of warp yarns are adjacent to each other. A conductive cloth obtained by metal-plating a mesh cloth having an opening formed by two adjacent weft threads among the plurality of weft threads, and the longitudinal direction of one warp of the plurality of warp threads. The one in the cross section when the one warp is cut in an orthogonal plane, or in the cross section when the one weft is cut in a plane orthogonal to the longitudinal direction of one of the plurality of wefts. The area defined by the maximum outer diameter of the warp or the one weft is smaller than the area of the opening surface of the opening.

It should be noted that this comprehensive or specific embodiment may be realized by any combination of systems, methods, integrated circuits, and the like.

The capacitance sensor and the like of the present disclosure can suppress a decrease in the reliability of the detection accuracy of the detection electrode by suppressing the occurrence of cracks in the detection electrode.

FIG. 1 is a diagram showing an example of a vehicle interior of a vehicle in which a capacitance sensor is arranged according to the first embodiment. FIG. 2 is a cross-sectional view showing the rim around which the steering cover is wound and the steering cover in line II-II of FIG. 1, and a partially enlarged cross-sectional view of the rim, the steering cover, and the rim. FIG. 3 is a diagram showing an example of how to wind the steering cover having the capacitance sensor according to the first embodiment around the rim. FIG. 4 is a block diagram showing the configuration of the capacitance sensor according to the first embodiment. FIG. 5 is a partially enlarged cross-sectional view showing the warp and weft of the detection electrode. FIG. 6 is a partially enlarged cross-sectional view showing a cross section of the warp threads and side surfaces of the weft threads of the detection electrode in the VI-VI line of FIG. FIG. 7 is a partially enlarged plan view showing a state before pulling the detection electrode, a state after pulling the detection electrode, and a partially enlarged plan view showing the state after compression of the detection electrode. FIG. 8 is a flowchart showing a method of manufacturing a capacitance sensor according to the first embodiment. FIG. 9 is a diagram showing the relationship between the resistance value and the time between the case where the mesh cloth is electroplated and the case where the mesh cloth is electroplated. FIG. 10 is a partially enlarged cross-sectional view showing warp threads and weft threads of a plain weave cloth which is a general woven fabric in a comparative example. FIG. 11 is a partially enlarged cross-sectional view showing a cross section of the warp threads of the non-woven fabric and side surfaces of the weft threads in the X-ray line of FIG. 10 in the comparative example. FIG. 12 is a cross-sectional view showing the rim around which the steering cover is wound and the steering cover in the line AA of FIG. 1, and a partially enlarged cross-sectional view of the rim, the steering cover, and the rim. FIG. 13 is a block diagram showing the configuration of the capacitance sensor according to the second embodiment. FIG. 14 is a plan view of the surface layer portion, the third adhesive layer, the moisture-proof layer, the first adhesive layer, the detection electrode, the second adhesive layer, and the base material in an overlapping manner. FIG. 15 is a cross-sectional view of an edge portion of the steering cover on the line BB of FIG. FIG. 16A is a schematic view showing a case where the current path is conducted along the warp or weft in the detection electrode of the capacitance sensor according to the second embodiment. FIG. 16B is a schematic view showing a case where the current path of the detection electrode of the capacitance sensor according to the second embodiment relies on the contact point between the warp and the weft to conduct the current. FIG. 17 is a block diagram showing the configuration of the capacitance sensor according to the third embodiment. FIG. 18 is a plan view of the surface layer portion, the third adhesive layer, the moisture-proof layer, the first adhesive layer, the detection electrode, the second adhesive layer, and the base material in an overlapping manner.

The capacitance sensor according to one aspect of the present disclosure includes a sheet-shaped base material having a front surface and a back surface, and a capacitance type detection electrode arranged on the front surface of the base material, and the detection is performed. The electrode has a plurality of warp yarns which are twisted wires and a plurality of weft yarns which are twisted wires, and is woven by the plurality of warp yarns and the plurality of weft yarns, and two adjacent warp yarns among the plurality of warp yarns are adjacent to each other. A conductive cloth obtained by metal-plating a mesh cloth having an opening formed by two adjacent weft threads among the plurality of weft threads, and the longitudinal direction of one warp of the plurality of warp threads. The one in the cross section when the one warp is cut in an orthogonal plane, or in the cross section when the one weft is cut in a plane orthogonal to the longitudinal direction of one of the plurality of wefts. The area defined by the maximum outer diameter of the warp or the one weft is smaller than the area of the opening surface of the opening.

As described above, since the area of the cross section of the warp and weft in the maximum outer diameter is smaller than the area of the opening surface of the opening, the mesh-shaped detection electrode has a large ratio of the opening to the unit area. Therefore, when a tensile stress is applied to the detection electrode by pulling the capacitance sensor, the detection electrode tends to stretch. That is, the detection electrode extends according to the tensile stress while changing the shape of the opening. When the detection electrode is stretched, since the plurality of warp threads and the plurality of weft threads are stranded wires, cracks are less likely to occur as compared with the non-woven fabric. That is, by suppressing the occurrence of cracks in the detection electrode, it is possible to suppress an increase in the resistance value.

Therefore, the capacitance sensor can suppress a decrease in the reliability of the detection accuracy of the detection electrode.

In particular, when the detection electrode is stretched, contact pressure is applied to the warp and the weft, so that the contact pressure at each contact point of the plurality of warp threads and the plurality of weft threads is stable, and the robustness of the detection electrode is further improved.

Further, in the method for manufacturing a capacitance sensor according to another aspect of the present disclosure, a plurality of warp yarns which are stranded wires and a plurality of weft yarns which are stranded wires are provided, and the plurality of warp yarns and the plurality of weft yarns are provided. A mesh cloth having an opening formed by two adjacent warp threads of the plurality of warp threads and two adjacent weft threads of the plurality of weft threads is subjected to electroless plating. A second step of forming a detection electrode by electrolytically plating the mesh cloth which has been subjected to the electroless plating in the first step, and a second step of arranging the detection electrode on the surface of a sheet-shaped base material. It has three steps, and is a cross section when the one warp is cut on a plane orthogonal to the longitudinal direction of one of the plurality of warp threads, or one of the plurality of weft threads. The area defined by the maximum outer diameter of the one warp or the one weft in the cross section when the one weft is cut in a plane orthogonal to the longitudinal direction is smaller than the area of the opening surface of the opening.

This production method also produces the same effects as described above.

Further, in the capacitance sensor according to another aspect of the present disclosure, the detection electrode is adhered to the surface of the base material, fixed to the base material, and the detection electrode when only the detection electrode is pulled. The elongation rate of the base material is larger than the elongation rate of the base material when only the base material is pulled.

In this way, when the capacitance sensor is pulled and stretched, the detection electrode can be stretched in the same manner as the base material, so that the occurrence of cracks in the detection electrode can be further suppressed.

Further, in the capacitance sensor according to another aspect of the present disclosure, the pulling direction when pulling the detection electrode has an acute angle with respect to the longitudinal direction of each of the plurality of warp threads and the plurality of weft threads. The direction is 45 °.

In this way, tensile stress is applied to the detection electrode so that the acute angle of the detection electrode is approximately 45 ° with respect to the longitudinal direction of each of the plurality of warp threads and the plurality of weft threads. Therefore, since the elongation rate of the detection electrode can be secured, it becomes easy to extend the capacitance sensor when it is pulled, and the occurrence of cracks due to the tensile stress in the detection electrode can be more reliably suppressed.

Further, in the capacitance sensor according to another aspect of the present disclosure, the pulling direction when pulling the base material is an acute angle of about 45 ° with respect to the longitudinal directions of the warp and the weft. Directionally, the substrate is fixed to the equipment in a pulled state.

In this way, the detection electrodes are arranged and fixed on the base material so that the pulling direction is approximately 45 ° at an acute angle with respect to the longitudinal directions of the warp and weft threads. That is, if the base material is pulled, the detection electrode can extend following the base material. Therefore, in this capacitance sensor, the occurrence of cracks in the detection electrode can be more reliably suppressed.

Further, in the capacitance sensor according to another aspect of the present disclosure, the metal plating is configured by further applying electrolytic nickel plating to the surface of the mesh cloth plated with electroless copper.

According to this, when electroplating a mesh cloth that has been electroless plated, a plurality of warp threads and a plurality of weft threads are composed of a plurality of twisted wires, so that the contact pressure between the warp threads and the weft threads is ensured. Since plating is performed in the state, the contact pressure at each contact point of the plurality of warp threads and the plurality of weft threads of the detection electrode is further improved, and the robustness of the detection electrode is further improved.

Further, since the detection electrode of the present disclosure has high crystallinity and high corrosion resistance as compared with the case where only electroless plating is applied to the mesh cloth, the resistance value of the detection electrode due to corrosion in the actual use environment is increased. It can be suppressed.

In addition, since the mesh cloth subjected to electroless plating has a large proportion of openings per unit area, the area to be plated is smaller than that of conventional non-woven fabrics, and the current value required for electrolytic plating is also relatively small. Become. Therefore, when electrolytic plating is used, an increase in power consumption can be suppressed. Therefore, it is possible to suppress an increase in the manufacturing cost of the capacitance sensor having the detection electrode.

Further, since metal plating can be formed by electroless plating a mesh cloth that has been electroless plated, for example, metal plating having excellent crystallinity can be applied to the surface of the mesh cloth without annealing treatment or the like. Can be formed. In particular, it is suitable when the mesh cloth is made of resin or the like.

Further, by further covering the mesh cloth plated with electroless copper with nickel electrolytic plating, it is possible to suppress the oxidation of the copper plating and improve the conductivity at the contact point where the warp and weft threads come into contact with each other. ..

Further, in the capacitance sensor according to another aspect of the present disclosure, the maximum width of the opening is smaller than the width of the finger of the human body.

In this way, the detection electrode can reliably detect the presence of a finger on the human body. Therefore, the capacitance sensor can ensure the detection accuracy.

Further, in the capacitance sensor according to another aspect of the present disclosure, when the detection electrode is viewed in a plan view, the first area, which is the area of overlap at each contact point between the one warp and the one weft, is , It is smaller than the second area, which is the area of the opening surface of the opening.

As described above, in the detection electrode, the contact area between the warp and the weft can be reduced as compared with the case where the first area is larger than the second area, so that the elongation rate of the detection electrode due to tension can be ensured. it can. Therefore, in this capacitance sensor, the occurrence of cracks in the detection electrode can be more reliably suppressed.

Further, the capacitance sensor according to another aspect of the present disclosure further includes a control circuit electrically connected to the detection electrode, and the detection electrode is arranged on the steering wheel, and the human body and the steering wheel. The control circuit is electrically connected to the detection electrode, and the detection electrode detects the contact between the human body and the steering wheel.

By electrically connecting the control circuit to the detection electrode in this way, it is possible to detect contact or grip with the steering wheel.

Further, in the capacitance sensor according to another aspect of the present disclosure, the openings are regularly arranged in substantially the same shape along the longitudinal direction of the warp and the longitudinal direction of the weft.

In this way, when the capacitance sensor is pulled and stretched and then wound around the steering wheel, tensile stress and partial compressive stress act on the respective openings, so that the respective openings change substantially regularly. Therefore, the stress applied to each contact point between the warp and the weft is substantially equal, so that the occurrence of cracks in the detection electrode can be suppressed more reliably.

The capacitance sensor according to one aspect of the present disclosure further includes a surface layer portion to be touched by a hand and a moisture-proof layer arranged on the back surface side of the surface layer portion, and the detection electrode is the moisture-proof layer of the moisture-proof layer. The base material is arranged on the side opposite to the surface layer side, the base material is arranged on the side opposite to the moisture-proof layer side of the detection electrode, and the moisture-proof layer and the detection electrode are the first adhesive layer. The detection electrode and the base material are attached by a second adhesive layer, and the moisture permeability of the moisture-proof layer is based on the moisture permeability of the first adhesive layer and the moisture permeability of the second adhesive layer. Is also low.

For example, when the user's hand touches the surface layer portion, the moisture such as sweat generated by the user's hand (for example, water vapor) is mixed with the residue contained in the material of the surface layer portion and becomes acidic corrosive water. Sometimes. Such corrosive water may permeate the inside of the capacitance sensor and reach the detection electrode. In this case, the detection electrode may be corroded by the corroded water.

However, according to the present disclosure, the moisture-proof layer is arranged on the back surface side of the surface layer portion and on the surface layer portion side of the detection electrode. That is, the moisture-proof layer is arranged outside the detection electrode. Further, the moisture permeability of the moisture-proof layer is lower than the moisture permeability of the first adhesive layer and the moisture permeability of the second adhesive layer. Therefore, even if the surface layer portion is in a high temperature and high humidity state when the user's hand touches the surface layer portion, the moisture-proof layer suppresses the moisture given by the user's hand from reaching the detection electrode. Can be done.

Therefore, in this capacitance sensor, corrosion of the detection electrode can be suppressed.

Further, in the capacitance sensor according to another aspect of the present disclosure, the first adhesive layer and the second adhesive layer are base material-less double-sided tapes.

This capacitance sensor is easier to stretch than the capacitance sensor using double-sided tape having a base material. That is, by using the base material-less double-sided tape for the capacitance sensor, it is difficult to excessively prevent the deformation of the opening of the detection electrode when the capacitance sensor is pulled. Therefore, it is possible to secure a constant tensile elongation rate of the capacitance sensor.

Further, the moisture-proof layer and the detection electrode can be adhered without impairing the extensibility, and the detection electrode and the base material can be adhered without impairing the extensibility. Therefore, the workability of assembling the capacitance sensor can be improved.

Further, in the capacitance sensor according to another aspect of the present disclosure, the thickness of the moisture-proof layer is thinner than the thickness of the first adhesive layer and the thickness of the second adhesive layer.

According to this, since the thickness of the moisture-proof layer is thin, the thickness of the capacitance sensor of the present disclosure is not so different from the thickness of the capacitance sensor without the moisture-proof layer. Therefore, for example, even when the capacitance sensor is wound around the rim of the steering wheel of the vehicle, it is unlikely that a problem such as difficulty in winding due to an increase in the thickness of the capacitance sensor will occur. In addition, since the step around the moisture-proof layer is also small, it is possible to reduce the driver's discomfort when gripping the steering wheel.

Further, in the capacitance sensor according to another aspect of the present disclosure, when the detection electrode, the moisture-proof layer, and the base material are overlapped, the surface area of the detection electrode is the surface area of the moisture-proof layer. The detection electrode is covered with the first adhesive layer and the second adhesive layer, which is smaller than the surface area of the base material.

According to this, even if the surface layer portion is in a high temperature and high humidity state, the detection electrode is covered in a state of being sandwiched between the first adhesive layer and the second adhesive layer, so that it becomes difficult for corrosive water to reach the detection electrode. .. As a result, in this capacitance sensor, corrosion of the detection electrode can be suppressed more reliably.

Further, in the capacitance sensor according to another aspect of the present disclosure, the surface layer portion and the moisture-proof layer are attached by a third adhesive layer, and the periphery of the third adhesive layer is the first adhesive layer. And is attached to the second adhesive layer.

According to this, since the detection electrode is in a state of being sealed by the third adhesive layer, the first adhesive layer and the second adhesive layer, it becomes difficult for corrosive water to reach the detection electrode. As a result, in this capacitance sensor, corrosion of the detection electrode can be suppressed more reliably.

Further, in the capacitance sensor according to another aspect of the present disclosure, a ground electrode is arranged on the side of the base material opposite to the detection electrode side.

For example, when the capacitance sensor is wound around the rim of the steering wheel, for example, in the present disclosure, the distance between the ground electrode and the detection electrode is compared with the distance between the conductive core metal included in the rim and the detection electrode. Can be made smaller. Therefore, the first capacitance between the ground electrode and the detection electrode is larger than the second capacitance between the core metal and the detection electrode. In other words, the sum of the capacitance from the hand to the detection electrode and the capacitance from the detection electrode to the ground electrode increases the sensitivity because it detects the contact of the hand with the surface layer, and the detection accuracy of the capacitance sensor. Can be further suppressed.

Further, in the capacitance sensor according to another aspect of the present disclosure, the third adhesive layer is a base material-less double-sided tape.

According to this, the surface layer portion and the moisture-proof layer can be adhered without impairing the extensibility. Therefore, the workability of assembling the capacitance sensor can be improved.

In the capacitance sensor according to one aspect of the present disclosure, the detection electrodes are a plurality of conductive cloths arranged at at least three places in the circumferential direction of the steering wheel, and each of the plurality of conductive cloths is an electrode. It has a portion and a signal extraction portion extending from the electrode portion to a predetermined position, and among the plurality of conductive cloths, the first conductive cloth that is closer to the predetermined position and the first conductive cloth that is farther from the predetermined position than the first conductive cloth. In the second conductive cloth, the first conductive cloth is arranged side by side in a direction orthogonal to the circumferential direction of the steering wheel in a state of being divided into two, and the signal extraction portion of the second conductive cloth is the said. It extends from the electrode portion of the second conductive cloth to the predetermined position along between the first conductive cloths divided into two without being electrically connected to the first conductive cloth.

For example, in order to detect which position of the steering wheel the user's hand is touching, the detection electrodes may be arranged at a plurality of places. In this case, the signal of the detection electrode is taken out from the signal extraction unit at the predetermined position, but among the detection electrodes arranged at a plurality of locations, the detection electrode arranged at a position far away from the predetermined position is the edge of the base material. The signal extraction unit may be pulled out to a predetermined position along the line. When the plurality of detection electrodes on which the signal extraction portion arranged in this way is formed and the vicinity of the base material or the like are sewn from above the surface layer portion with sewing thread, they are usually sewn along the edge of the base material. Therefore, the stress due to sewing is applied to the signal extraction portion arranged at the edge of the base material. Since the signal extraction portion is a leader wire thinner than the width of the detection electrode, it may be damaged by this stress.

Further, the steering wheel is placed in a high temperature and high humidity state by keeping the user's hand in contact with the steering wheel. Therefore, when the user's hand touches the surface layer of the steering wheel, moisture such as sweat (for example, water vapor) generated by the user's hand invades from the sewn portion and extracts a signal arranged at the edge of the base material. May reach the department. In this case, the narrow signal extraction portion has an extremely small width as compared with the detection electrode, and therefore has low corrosion resistance. As a result, when corrosion occurs, the capacitance sensor is likely to malfunction.

However, according to the present disclosure, the first conductive cloth divided into two is arranged side by side in a direction orthogonal to the circumferential direction of the steering wheel. Further, the signal take-out line of the second conductive cloth located at a position farther than the first conductive cloth from the predetermined position is arranged along between the two divided first conductive cloths. That is, since the signal take-out line of the second conductive cloth is sandwiched between the first conductive cloth divided into two and arranged in the central portion of the base material, the stress due to sewing is applied to the signal take-out line of the second conductive cloth. hard.

Further, since the signal take-out line of the second conductive cloth is arranged at a position away from the sewn position (sewing thread), moisture such as sweat generated by the user's hand invades from the sewn portion. However, it becomes difficult to corrode.

Therefore, in this capacitance sensor, damage and corrosion of the signal extraction portion can be suppressed.

Further, in the capacitance sensor according to another aspect of the present disclosure, when the plurality of conductive cloths, the surface layer portion, and the base material are viewed in an overlapping manner, the total surface area of the plurality of conductive cloths is determined. The surface area of the surface layer portion and the surface area of the base material are smaller than the surface area of the base material, and the plurality of conductive cloths are covered with the first adhesive layer and the second adhesive layer.

According to this, even if the surface layer portion is in a high temperature and high humidity state, the detection electrode, which is a conductive cloth, is covered in a state of being sandwiched between the first adhesive layer and the second adhesive layer, so that moisture is applied to the detection electrode. It becomes more difficult to reach. As a result, in this capacitance sensor, corrosion of the detection electrode can be suppressed more reliably.

Further, in the capacitance sensor according to another aspect of the present disclosure, a ground electrode is arranged on the side of the base material opposite to the detection electrode side.

For example, when the capacitance sensor is wound around the steering rim, for example, in the present disclosure, the distance between the ground electrode and the sensor electrode is compared with the distance between the conductive core metal included in the rim and the sensor electrode. Can be made smaller. Therefore, the first capacitance between the ground electrode and the sensor electrode is larger than the second capacitance between the core metal and the sensor electrode. In other words, the sum of the capacitance from the hand to the sensor electrode and the capacitance from the sensor electrode to the ground electrode increases the sensitivity because it detects the contact of the hand with the surface layer, and the detection accuracy of the capacitance sensor. Can be further suppressed.

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

It should be noted that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, the order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present disclosure. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components.

Further, each figure is a schematic view and is not necessarily exactly illustrated. Further, in each figure, the same components are designated by the same reference numerals. Further, in the following embodiments, expressions such as a substantially T character are used. For example, a substantially T-shape not only means that it is completely T-shaped, but also means that it is substantially T-shaped, that is, it includes an error of, for example, about several percent. Further, the substantially T-shape means a T-shape within the range in which the effects of the present disclosure can be achieved. The same applies to expressions using other "abbreviations".

(Embodiment 1)
<Configuration: Capacitance sensor 100>
FIG. 1 is a diagram showing an example of a passenger compartment of a vehicle 1 in which the capacitance sensor 100 according to the first embodiment is arranged.

As shown in FIG. 1, the 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, a warning device.

The steering wheel 3 provides a steering angle to the steering wheels of the vehicle 1. The steering wheel 3 includes a rim 31, a substantially T-shaped spoke 32 integrally formed on the inner peripheral surface of the rim 31, and a horn that covers a horn switch (not shown) arranged in the central portion of the spoke 32. It has a switch cover (not shown).

FIG. 2 is a cross-sectional view showing the rim 31 around which the steering cover 110 is wound and the steering cover 110 in line II-II of FIG. 1, and a partially enlarged cross-sectional view of the rim 31, the steering cover 110, and the rim 31. FIG. 3 is a diagram showing an example of how to wind the steering cover 110 having the capacitance sensor 100 according to the first embodiment around the rim 31.

As shown in FIGS. 2 and 3, the capacitance sensor 100 is a device that detects the contact of the steering cover 110 by the hand of the user (human body), and is provided on the rim 31 of the vehicle 1. The contact means not only that the user's hand comes into direct contact with the steering cover 110, but also includes a state in which the capacitance sensor 100 is separated from the steering cover 110 if the capacitance sensor 100 can detect the human hand. is there.

The capacitance sensor 100 is, for example, a capacitance type proximity sensor, which is a grip sensor that detects the grip of a user in a vehicle 1 having a steering wheel 3. Specifically, the capacitance sensor 100 detects a change in capacitance between the user's hand and the detection electrode 112 in the capacitance sensor 100, so that the user's hand touches the steering wheel 3. Detects whether or not it is. When the user's hand is away from the steering wheel 3, the capacitance sensor 100 detects the capacitance between the vehicle 1 and the detection electrode 112. Further, when the user's hand approaches or comes into contact with the steering cover 110, the capacitance changes because the user's hand intervenes between the capacitance sensor 100 and the vehicle body. If the detected capacitance is equal to or greater than the specified value, it can be determined that the user's hand is touching or gripping the steering wheel 3.

FIG. 4 is a block diagram showing the configuration of the capacitance sensor 100 according to the first embodiment.

As shown in FIGS. 2 and 4, the capacitance sensor 100 includes a surface layer portion 111, a detection electrode 112, a base material 113, a ground electrode 114, and a control device 120.

[Surface layer 111]
The surface layer portion 111 is a portion touched by a hand and constitutes the outer circumference of the capacitance sensor 100. That is, the surface layer portion 111 is a portion that comes into direct contact with the user's hand when the user grips the rim 31. Further, the surface layer portion 111 is made of leather, wood, resin or the like, and is leather in the present embodiment.

[Detection electrode 112]
The detection electrode 112 is arranged on the steering wheel 3. Specifically, the detection electrode 112 is arranged on the back surface of the surface layer portion 111 and on the surface 113a of the base material 113. That is, the detection electrode 112 is sandwiched between the surface layer portion 111 and the base material 113. The detection electrode 112 is adhered to the back surface of the surface layer portion 111 by the first adhesive layer 116b, adhered to the surface 113a of the base material 113 by the second adhesive layer 116c, and fixed to the base material 113. The surface 113a of the base material 113 is a surface arranged toward the surface layer portion 111 side.

Only one detection electrode 112 may be arranged on the surface 113a of the base material 113, or a plurality of detection electrodes 112 may be arranged. As shown in FIG. 4, in the present embodiment, the case where the capacitance sensor 100 has three detection electrodes 112 and three ground electrodes 114 is illustrated, and the description will be described below with reference to this figure. For convenience, the description mainly focuses on the detection electrode 112 of the three detection electrodes 112 and the ground electrode 114 of one of the three ground electrodes 114.

In the present embodiment, the first detection electrode of the three detection electrodes 112 is viewed at one end (for example, facing the rim 31) when the capacitance sensor 100 is wound around the rim 31. Is placed on the right side of). The second detection electrode 112, which is another electrode of the three detection electrodes 112, is the other end side when the capacitance sensor 100 is wound around the rim 31 (for example, when viewed in a state of facing the rim 31). It is placed on the left side). The third detection electrode 112, which is the remaining electrode of the three detection electrodes 112, is arranged between the first detection electrode 112 and the second detection electrode 112.

FIG. 5 is a partially enlarged cross-sectional view showing the warp threads 132a and the weft threads 132b of the detection electrode 112.

As shown in FIG. 5, the detection electrode 112 is, for example, a conductive cloth formed by plating a non-metal fiber, and is a capacitance type sensor electrode. Specifically, the detection electrode 112 forms a first metal plating on the surface of a mesh cloth woven with non-metal fibers such as polyethylene terephthalate (PET), and further, a second metal plating on the surface of the first metal plating. Is formed and constructed. Alternatively, the detection electrode 112 is formed by forming a first metal plating on the surface of a non-metal fiber such as polyethylene terephthalate (PET), and further weaving a conductive fiber having a second metal plating formed on the surface of the first metal plating. It is formed. For example, the first metal plating is copper or the like, and the second metal plating is nickel or the like.

Specifically, the detection electrode 112 includes a plurality of warp threads 132a which are stranded wires formed by twisting a plurality of wires (the above-mentioned non-metal fibers) into one wire, and a plurality of stranded wires. It has a weft thread 132b. In the detection electrode 112, an opening 132c is formed by two adjacent warp threads 132a among the plurality of warp threads 132a and two adjacent weft threads 132b among the plurality of weft threads 132b, and the plurality of warp threads 132a and the plurality of weft threads are formed. It is a conductive cloth in which metal plating is applied to a mesh cloth woven with 132b.

Here, the opening 132c has a rectangular shape when the detection electrode 112 is viewed in a plan view. The openings 132c are regularly arranged in substantially the same shape along the longitudinal direction of the warp threads 132a and the longitudinal direction of the weft threads 132b. In this embodiment, the openings 132c are arranged in a grid pattern. The maximum width L1 of the opening 132c is smaller than the width of the human finger. Here, the width of the fingers of the human body may be the width of one finger, or may be up to the width of two or more and five or less fingers. That is, the maximum width L1 of the opening 132c is determined in accordance with the width of the finger of the human body defined in consideration of the threshold value of the capacitance to be determined to be gripped.

Each of the plurality of warp threads 132a is arranged at a shape of approximately 45 ° with respect to the longitudinal direction or the lateral direction of the detection electrode 112 when the detection electrode 112 is viewed in a plan view in a state where the steering cover 110 is not wound around the rim 31. Further, each of the plurality of weft threads 132b is arranged substantially linearly in a posture substantially orthogonal to each of the plurality of warp threads 132a when the detection electrode 112 is viewed in a plan view in a state where the steering cover 110 is not wound around the rim 31. Will be done. That is, in the mesh cloth, a plurality of openings 132c are formed by weaving a plurality of warp threads 132a and a plurality of weft threads 132b.

FIG. 6 is a partially enlarged cross-sectional view showing a cross section of the warp thread 132a of the detection electrode 112 and a side surface of the weft thread 132b in the VI-VI line of FIG.

As shown in FIGS. 5 and 6, since the mesh cloth formed by weaving each of the plurality of warp threads 132a and each of the plurality of weft threads 132b is metal-plated, the plurality of warp threads 132a and the plurality of warp threads 132a are formed. Needless to say, each contact P with the weft 132b is electrically connected. Here, the metal plating is configured by further applying electrolytic nickel plating to the surface of the mesh cloth plated with electroless copper. Here, the contact P is a portion where each of the plurality of warp threads 132a and each of the plurality of weft threads 132b overlap and contact (conduct).

Further, in the present embodiment, the electroless nickel plating is further applied to the electroless copper plated mesh cloth as compared with the case where the electroless copper plated mesh cloth is subjected to the electroless nickel plating. Since the detection electrode 112 of the present embodiment has high crystallinity and high corrosion resistance, it is possible to suppress an increase in the resistance value of the detection electrode 112 due to corrosion in an actual use environment. Further, since the plurality of warp threads 132a and the plurality of weft threads 132b are composed of a plurality of twisted wires, the mesh cloth is plated in a state where the contact pressure between the warp threads 132a and the weft threads 132b is sufficiently secured. Therefore, since the contact pressure at the contact points P of the plurality of warp threads 132a and the plurality of weft threads 132b of the detection electrode 112 is improved, the warp threads 132a and the weft threads 132b are firmly connected at the contact points P. Further, when the capacitance sensor 100 is pulled, contact pressure is applied to the warp threads 132a and the weft threads 132b, so that the contact pressures at the contact points P of the plurality of warp threads 132a and the plurality of weft threads 132b are stable. The connection of the contact point P between the warp thread 132a and the weft thread 132b becomes stronger.

As shown in FIG. 5, the maximum outside indicated by the alternate long and short dash line of one warp 132a in the cross section when one warp 132a is cut in a plane orthogonal to the longitudinal direction of one warp 132a among the plurality of warp 132a. The area defined by the diameter is smaller than the area of the opening surface of the opening 132c. Further, in the cross section when one weft thread 132b is cut in a plane orthogonal to the longitudinal direction of one weft thread 132b among the plurality of weft threads 132b, the area A1 defined by the maximum outer diameter of one weft thread 132b is an opening. It is smaller than the area A2 of the opening surface of 132c. Here, the maximum outer diameter is, for example, the maximum value of the diameter defined by a circle or the like in the warp threads 132a and the weft threads 132b. In FIG. 5, the area A1 indicated by the alternate long and short dash line is shown only for comparison with A2 indicated by the alternate long and short dash line.

Further, the elongation rate of the detection electrode 112 when only the detection electrode 112 is pulled is larger than the elongation rate of the base material 113 when only the base material 113 is pulled. The elongation rate of the detection electrode 112 increases as the area of the opening surface of the opening 132c becomes larger than the area defined by the maximum outer diameters of the warp threads 132a and the weft threads 132b.

FIG. 7 is a partially enlarged view showing a state before pulling the detection electrode 112, a state after pulling the detection electrode 112 (for example, the detection electrode 112 after winding the steering wheel 3 around the rim 31), and the detection electrode 112. It is a partially enlarged plan view which shows the state after compression of.

As shown in FIG. 7, since the detection electrode 112 is a mesh-shaped conductive cloth, if the detection electrode 112 is pulled in a direction intersecting the longitudinal direction of each of the plurality of warp threads 132a and the plurality of weft threads 132b, the pulling direction and the pulling direction can be determined. Each of the plurality of warp threads 132a and the plurality of weft threads 132b moves so that the angle θ1 of the plurality of warp threads 132a and the plurality of weft threads 132b with respect to the longitudinal direction becomes small. When only the detection electrode 112 is pulled, the detection electrode 112 extends while the shape of the plurality of openings 132c is deformed so that the shape of the plurality of openings 132c of the detection electrode 112 changes from a rectangular shape to a diamond shape. That is, the tensile stress applied to the warp threads 132a and the weft threads 132b can be suppressed. Further, when the detection electrode 112 is compressed (after compression), the shape of the opening 132c of the detection electrode 112 also changes. That is, the compressive stress applied to the warp threads 132a and the weft threads 132b can be suppressed. In both cases of tension and compression, the warp threads 132a and the weft threads 132b are firmly connected by the contact point P in FIG. 6, so that the form of conduction shown in FIG. 16B, which will be described later, is not hindered.

Specifically, the straight line W substantially parallel to the pulling direction when the detection electrode 112 is pulled becomes a straight line V1 substantially parallel to the longitudinal direction of the plurality of warp threads 132a and a straight line V2 substantially parallel to the longitudinal direction of the plurality of weft threads 132b. On the other hand, the sharp angle θ1 is approximately 45 °. That is, since the detection electrode 112 is pulled in the direction in which it is most easily stretched, the detection electrode 112 has a straight line W substantially parallel to the pulling direction when the base material 113 is pulled, a straight line V1 parallel to the longitudinal direction of the warp 132a, and the straight line V1. It is fixed to the surface 113a of the base material 113 in a posture in which the acute angle θ1 in the straight line V2 parallel to the longitudinal direction of the weft 132b is approximately 45 °. Even if the capacitance sensor 100 is pulled in the longitudinal direction and the lateral direction when the capacitance sensor 100 is wound around the rim 31, the elongation rate of the detection electrode 112 is larger than the elongation rate of the base material 113, so that the base material 113 The detection electrode 112 extends following the above.

Further, it goes without saying that the angle θ1 is approximately 45 ° or less because the detection electrode 112 after the steering wheel 3 is wound around the rim 31 is in a pulled state.

Further, as shown in FIG. 5, when the detection electrode 112 is viewed in a plan view, the first area 112d, which is the area of overlap at the contact points P between each of the plurality of warp threads 132a and each of the plurality of weft threads 132b, has an opening 132c. It is smaller than the second area A2, which is the area of the opening surface of. That is, in the present embodiment, the first area 112d of the detection electrode 112 is made smaller than the second area A2 as compared with the detection electrode in which the first area 112d is larger than the second area A2. The contact area between each of the 132a and each of the plurality of weft threads 132b becomes smaller. As a result, the amount of deformation due to the opening can be further secured, so that the detection electrode 112 tends to stretch due to tensile stress.

Since the detection electrode 112 stretches using the opening 132c, the stress applied to the plurality of warp threads 132a and the plurality of weft threads 132b during stretching is higher than that of the metal-plated non-woven fabric or plain weave cloth (configuration of FIG. 10 described later). Extremely small. Therefore, the influence of stress on the warp threads 132a and the weft threads 132b such as cracks on the metal plating is reduced, and high reliability can be obtained.

[Base material 113]
The base material 113 is a non-woven fabric formed in the form of a long sheet by a material having elasticity, flexibility and ductility. For example, the base material 113 is made of a synthetic resin such as polyethylene (PE) and polyethylene terephthalate (PET). The base material 113 is formed according to the shape and size of the rim 31.

Further, the base material 113 has a front surface 113a and a back surface 113b. The detection electrode 112 is arranged on the front surface 113a via the second adhesive layer 116c, and the ground electrode 114 is arranged on the back surface 113b. The base material 113 is arranged on the side opposite to the surface layer portion 111 side of the detection electrode 112, and is arranged on the surface of the ground electrode 114 on the detection electrode 112 side. That is, the base material 113 is sandwiched between the detection electrode 112 and the ground electrode 114.

Further, when the steering seat is wound around the rim 31, the base material 113 is fixed to the rim 31 with the installation electrode sandwiched in a pulled state. Here, the rim 31 is an example of equipment. That is, the equipment is not limited to the rim 31 because it is an object to which the capacitance sensor 100 is attached.

[Ground electrode 114]
The ground electrode 114 is a metal wire (conductive wire) such as a copper wire. Each of the ground electrodes 114 is electrically connected to the control circuit 121 via wirings 119b, 119c, etc., and is grounded.

The ground electrode 114 may be a solid electrode having a planar structure made of a conductor or a resistor. That is, the ground electrode 114 may be linear or plate-shaped. The ground electrode 114 is made of a conductive wire, but may have any form as long as it is a conductive member.

The ground electrode 114 is arranged on the side opposite to the detection electrode 112 of the base material 113, that is, on the back surface 113b of the base material 113 and on the surface of the rim 31, and is adhered to the surface of the rim 31 with the adhesive 116a. That is, the ground electrode 114 is sandwiched between the rim 31 and the base material 113. For example, the ground electrode 114 is sewn on the base material 113 by a sewing thread. The back surface 113b of the base material 113 is a surface arranged toward the rim 31 side of the steering wheel 3.

In the present embodiment, the first adhesive layer 116b and the second adhesive layer 116c are base-less double-sided tapes. That is, the first adhesive layer 116b and the second adhesive layer 116c are composed of only an adhesive. The thickness of the first adhesive layer 116b and the second adhesive layer 116c is, for example, about 100 μm, but is not limited to this thickness. The adhesive 116a, the first adhesive layer 116b, and the second adhesive layer 116c may or may not be included in the constituent requirements of the capacitance sensor 100. The adhesive 116a, the first adhesive layer 116b, and the second adhesive layer 116c are, for example, an adhesive, double-sided tape, or the like.

In the present embodiment, one of the ground electrodes 114 corresponds to the detection electrode 112 and is arranged on one side (for example, the right side) when the capacitance sensor 100 is wound around the rim 31. ing. Further, the other ground electrode 114 of the pair of ground electrodes 114 corresponds to the other detection electrode 112, and is arranged on the other side (for example, the left side) when the capacitance sensor 100 is wound around the rim 31. ..

[Control device 120]
The control device 120 is embedded in the spokes 32, for example. The control device 120 is electrically connected to the ground electrode 114 and the detection electrode 112, and detects the contact of the steering wheel 3 by the user's hand based on the signal transmitted from the detection electrode 112. That is, the control device 120 measures that the user's hand comes into contact with the surface layer portion 111. That is, the control device 120 detects whether or not the user's hand is in contact with the rim 31, that is, detects the contact of the hand, the contact position of the hand, and the like.

The control device 120 includes a control circuit 121 and a power supply circuit 122.

The control circuit 121 has a sensor circuit that detects the contact between the human body and the steering wheel 3 by the detection electrode 112. The control circuit 121 is electrically connected to each detection electrode 112, and the detection electrode 112 detects the contact between the human body and the steering wheel 3.

Specifically, the control circuit 121 applies an alternating current to the three detection electrodes 112 via the wirings 119a, 119b, and 119c, that is, applies a measurement potential to the detection electrodes 112. The control circuit 121 is electrically connected to the three detection electrodes 112 by wirings 119a, 119b, and 119c. When a hand comes into contact with the surface layer portion 111 of the rim 31, the capacitance of the detection electrode 112 corresponding to the contact portion changes, so that the control circuit 121 is based on the current value (measurement potential) of the current flowing through the detection electrode 112. , The change in capacitance at the detection electrode 112 is measured. In this way, the control circuit 121 can detect whether or not the hand has come into contact with the steering wheel 3 from the signal indicating the change in capacitance output from the detection electrode 112.

The power supply circuit 122 is electrically connected to the control circuit 121 via the wirings 119a, 119b, and 119c, and is controlled by the control circuit 121. Further, the power supply circuit 122 is electrically connected to the ground electrode 114 via wirings 119a, 119b, 119c and the like. The power supply circuit 122 applies a measurement potential to the detection electrode 112 by the control circuit 121.

The power supply circuit 122 may be controlled by the control circuit 121 so that a direct current flows through the ground electrode 114. That is, the ground electrode 114 may have a function as a heater by flowing a direct current. In this case, since only a direct current flows through the ground electrode 114, it is grounded when viewed from the alternating current flowing through the detection electrode 112. The ground electrode 114 is not limited to a configuration having a heater function, and may be simply grounded without passing a direct current.

<Manufacturing method>
Next, a method of manufacturing the capacitance sensor 100 will be described.

FIG. 8 is a flowchart showing a method of manufacturing the capacitance sensor 100 according to the first embodiment.

First, a mesh cloth having a plurality of warp threads 132a as stranded wires and a plurality of weft threads 132b as stranded wires, an electroless plating solution, and an electrolytic plating apparatus are prepared. The mesh cloth is woven with a plurality of warp threads 132a and a plurality of weft threads 132b, and is formed by two adjacent warp threads 132a among the plurality of warp threads 132a and two adjacent weft threads 132b among the plurality of weft threads 132b. It has an opening 132c. Then, as shown in FIG. 8, the mesh cloth is immersed in the electroless plating solution, and the surface of the mesh cloth is electroless plated (S11: first step).

Next, the mesh cloth that has been electroless-plated in the first step is immersed in an electroplating solution, and an electric current is passed through the electroplating device to electroplat the surface of the mesh cloth that has been electroless-plated. Is given. In this way, the detection electrode 112 is generated (S12: second step). Here, when the wire diameter of the stranded wire of the conductive cloth becomes large and the area of the opening becomes small, the effective electrode area at the time of performing electrolytic plating increases, so that the current value required for electrolytic plating increases. In the case of electroplating, considering the actual current value that can be supplied by the electroplating device, for example, the area of the opening surface of the opening of the conductive cloth is limited to about 0.05 square millimeters, and the area of the opening is larger than this. If it becomes smaller (for example, about 0.04 square millimeter), it may not be possible to supply the current value required for electroplating. In this way, the wire diameter of the stranded wire of the conductive cloth may be determined in consideration of the correlation between the current value that can be supplied by the electroplating apparatus at the time of electroplating and the opening area.

Next, the detection electrode 112 is arranged on the surface 113a of the sheet-shaped base material 113 (S13: third step). In this way, the capacitance sensor 100 can be obtained.

<Experimental results>
The difference in resistance between the electroless-plated mesh cloth and the electroplated mesh cloth will be described.

FIG. 9 is a diagram showing the relationship (corrosion resistance comparison) between the resistance value and the time when the mesh cloth is electroless plated only and when the mesh cloth is also electroplated. The case where only electroless plating is performed is shown by a alternate long and short dash line, and the case where electroplating is also performed is shown by a solid line.

As shown in FIG. 9, it was obtained that the electroless-plated mesh cloth had a larger rate of increase in resistance value with the passage of time than the electroless-plated mesh cloth. Therefore, the detection electrode 112 is also electroplated on a mesh cloth.

<Comparison example>
Next, the plain weave fabric of the comparative example will be described with reference to FIGS. 10 and 11.

FIG. 10 is a partially enlarged cross-sectional view showing the warp threads 191a and the weft threads 191b of the plain weave cloth 191 which is a general woven fabric in the comparative example. FIG. 11 is a partially enlarged cross-sectional view showing a cross section of the warp 191a of the plain weave cloth 191 and a side surface of the weft 191b in the XX line of FIG. 10 in the comparative example. The plain weave cloth 191 will be described below assuming that the plain weave cloth 191 is metal-plated and has conductivity like the detection electrode 112 of the present embodiment.

As shown in FIG. 10, the plain weave cloth 191 of the comparative example is a plain weave cloth having a plurality of sheet-shaped warp threads 191a and a plurality of sheet-shaped weft threads 191b.

Each of the plurality of warp threads 191a and the plurality of weft threads 191b is a sheet-like thread in which wires are bundled or entwined. The warp threads 191a and weft threads 191b are not stranded wires.

Further, it is defined by the maximum outer diameter indicated by the alternate long and short dash line of one warp 191a in the cross section when one warp 191a is cut in a plane orthogonal to the longitudinal direction of one warp 191a among the plurality of warp 191a. The area is larger than the area of the opening surface of the opening. Further, the area B2 defined by the maximum outer diameter of one weft thread 191b in the cross section when one weft thread 191b is cut in a plane orthogonal to the longitudinal direction of one weft thread 191b among the plurality of weft threads 191b is an opening. It is larger than the area B1 of the opening surface of. In FIG. 10, the area B2 indicated by the alternate long and short dash line is shown only for comparison with B1 indicated by the alternate long and short dash line.

As shown in FIG. 11, in the cross section of the plain weave cloth 191, gaps are formed in the lines forming each of the warp threads 191a and the weft threads 191b. That is, the warp threads 191a and the weft threads 191b have a lower line density per unit area than the warp threads 132a and the weft threads 132b of the detection electrode 112 of the present embodiment.

In this case, in the plain weave cloth 191 of the comparative example, since there are more gaps than the warp threads 132a and the weft threads 132b of the detection electrode 112 of the present embodiment, cracks are likely to occur when the plain weave cloth 191 is pulled in the pulling direction. Further, in a plain weave fabric, when a tensile stress is applied, the opening shape is changed and the fabric does not stretch according to the tensile stress, but the stress is applied to the warp and weft threads themselves, so that cracks occur. It's easy to do.

Further, in this case, in the plain weave cloth 191 of the comparative example, the contact resistance between the warp yarn 191a and the weft yarn 191b is difficult to stabilize, and the resistance value of the contact point tends to increase. Further, in the warp threads 191a and the weft threads 191b, when metal plating is performed by electrolytic plating, the required current value is determined by the surface area of the object to be plated. Therefore, in the plain weave cloth 191 in which the area to be plated per unit area of the cloth is larger than that of the mesh cloth, the current value increases at the time of electrolytic plating. Therefore, it is difficult to electroplat the warp threads 191a and weft threads 191b. Further, even if the warp threads 191a and the weft threads 191b can be metal-plated by electrolytic plating, the manufacturing cost of the plain weave cloth 191 will increase.

<Effect>
As described above, the capacitance sensor 100 in the present embodiment detects the capacitance type arranged on the sheet-shaped base material 113 having the front surface 113a and the back surface 113b and the surface 113a of the base material 113. It includes an electrode 112. The detection electrode 112 has a plurality of warp threads 132a which are stranded wires and a plurality of weft threads 132b which are stranded wires. The detection electrode 112 is woven by a plurality of warp threads 132a and a plurality of weft threads 132b, and is formed by two adjacent warp threads 132a among the plurality of warp threads 132a and two adjacent weft threads 132b among the plurality of weft threads 132b. It is a conductive cloth in which metal plating is applied to a mesh cloth having an opening 132c to be formed. Then, the cross section when one warp 132a is cut on a plane orthogonal to the longitudinal direction of one warp 132a among the plurality of warp 132a, or orthogonal to the longitudinal direction of one weft 132b among the plurality of weft 132b. The area A1 defined by the maximum outer diameter of one warp 132a or one weft 132b in the cross section when one weft 132b is cut on the plane is smaller than the opening surface A2 of the opening 132c.

As described above, since the area of the warp threads 132a and the weft threads 132b at the maximum outer diameter of the cross section is smaller than the area A2 of the opening surface of the opening 132c, the mesh-shaped detection electrode 112 has a ratio of the opening 132c to the unit area. large. Therefore, when a tensile stress is applied to the detection electrode 112 by pulling the capacitance sensor 100, the detection electrode 112 tends to stretch. That is, the detection electrode 112 extends according to the tensile stress while changing the shape of the opening 132c. As a result, tensile stress is less likely to be applied to the plurality of warp threads 132a and the plurality of weft threads 132b. When the detection electrode 112 is stretched, the plurality of warp threads 132a and the plurality of weft threads 132b are stranded wires, and are therefore stronger than the non-woven fabric that is not stranded wires. Therefore, cracks are unlikely to occur. That is, the capacitance sensor 100 can suppress an increase in the resistance value by suppressing the occurrence of cracks in the detection electrode 112.

Therefore, the capacitance sensor 100 can suppress a decrease in the reliability of the detection accuracy of the detection electrode 112.

In particular, when the detection electrode 112 is extended, contact pressure is applied to the warp threads 132a and the weft threads 132b, so that the contact pressures at the contact points P of the plurality of warp threads 132a and the plurality of weft threads 132b are stable, and the detection electrode 112 is more robust. Improves sex.

Further, in the method of manufacturing the capacitance sensor 100 according to the present embodiment, the plurality of warp threads 132a which are stranded wires and the plurality of weft threads 132b which are stranded wires are provided, and the plurality of warp threads 132a and the plurality of weft threads 132b are included. A mesh cloth having an opening 132c formed by two adjacent warp threads 132a among a plurality of warp threads 132a and two adjacent weft threads 132b among a plurality of weft threads 132b is subjected to electroless plating. The first step, the second step of electrolytically plating the mesh cloth subjected to the electrolytic plating in the first step to generate the detection electrode 112, and the detection electrode 112 are arranged on the surface 113a of the sheet-shaped base material 113. The cross section when one warp 132a is cut in a plane orthogonal to the longitudinal direction of one warp 132a among the plurality of warp 132a, or one of the plurality of weft 132b. The area defined by the maximum outer diameter of one warp 132a or one weft 132b in the cross section when one weft 132b is cut in a plane orthogonal to the longitudinal direction of one weft 132b is the area of the opening surface of the opening 132c. Smaller than

This production method also produces the same effects as described above.

Further, in the capacitance sensor 100 of the present embodiment, the detection electrode 112 is adhered to the surface 113a of the base material 113 and fixed to the base material 113. The elongation rate of the detection electrode 112 when only the detection electrode 112 is pulled is larger than the elongation rate of the base material 113 when only the base material 113 is pulled.

In this way, when the capacitance sensor 100 is pulled and stretched, the detection electrode 112 can be stretched in the same manner as the base material 113, so that the occurrence of cracks in the detection electrode 112 can be further suppressed.

Further, in the capacitance sensor 100 according to the present embodiment, the pulling direction when pulling the detection electrode 112 has an acute angle of about 45 ° with respect to the longitudinal direction of each of the plurality of warp threads 132a and the plurality of weft threads 132b. Is the direction.

In this way, tensile stress is applied to the detection electrode 112 so that the acute angle of the detection electrode 112 is approximately 45 ° with respect to the longitudinal direction of each of the plurality of warp threads 132a and the plurality of weft threads 132b. Therefore, since the elongation rate of the detection electrode 112 can be secured, it becomes easy to extend the capacitance sensor 100 when it is pulled, and the occurrence of cracks due to the tensile stress in the detection electrode 112 can be more reliably suppressed. it can.

Further, in the capacitance sensor 100 of the present embodiment, the pulling direction when pulling the base material 113 is a direction in which the acute angle is approximately 45 ° with respect to the longitudinal directions of the warp threads 132a and the weft threads 132b, respectively. is there. Then, the base material 113 is fixed to the equipment in a pulled state.

In this way, the detection electrode 112 is arranged and fixed on the base material 113 so that the acute angle is approximately 45 ° with respect to the longitudinal directions of the warp threads 132a and the weft threads 132b in the pulling direction. That is, if the base material 113 is pulled, the detection electrode 112 can extend following the base material 113. Therefore, in this capacitance sensor 100, the occurrence of cracks in the detection electrode 112 can be more reliably suppressed.

Further, in the capacitance sensor 100 according to the present embodiment, the metal plating is formed by further applying electrolytic nickel plating to the surface 113a in which the mesh cloth is plated with electroless copper.

According to this, when electroplating a mesh cloth subjected to electroless plating, since the plurality of warp threads 132a and the plurality of weft threads 132b are composed of a plurality of twisted wires, the contact pressure between the warp threads 132a and the weft threads 132b Since plating is performed in a state where the above-mentioned is secured, the contact pressure at each contact point P of the plurality of warp threads 132a and the plurality of weft threads 132b of the detection electrode 112 is further improved, and the robustness of the detection electrode 112 is further improved.

Further, as compared with the case where only electroless plating is applied to the mesh cloth, the detection electrode 112 of the present embodiment has high crystallinity and high corrosion resistance, so that the resistance of the detection electrode 112 due to corrosion in an actual use environment The increase in value can be suppressed.

In addition, since the mesh cloth subjected to electroless plating has a large ratio of the opening 132c to the unit area, the area to be plated is smaller than that of the conventional non-woven fabric, and the current value required for electrolytic plating is relatively large. It becomes smaller. Therefore, when electrolytic plating is used, an increase in power consumption can be suppressed. Therefore, it is possible to suppress an increase in the manufacturing cost of the capacitance sensor 100 having the detection electrode 112.

Further, since metal plating can be formed by electroless plating a mesh cloth that has been electroless plated, for example, metal plating having excellent crystallinity can be applied to the surface of the mesh cloth without annealing treatment or the like. Can be formed. In particular, it is suitable when the mesh cloth is made of resin or the like.

Further, by further covering the mesh cloth plated with electroless copper with nickel electrolytic plating, oxidation of the copper plating can be suppressed, and the conductivity at the contact point P where the warp threads 132a and the weft threads 132b come into contact is also improved. be able to.

Further, in the capacitance sensor 100 according to the present embodiment, the maximum width L1 of the opening 132c is smaller than the width of the finger of the human body.

In this way, the detection electrode 112 can reliably detect the presence of a finger on the human body. Therefore, the capacitance sensor 100 can ensure the detection accuracy.

Further, in the capacitance sensor 100 according to the present embodiment, when the detection electrode 112 is viewed in a plan view, the first area 112d, which is the area of overlap at each contact point P between one warp thread 132a and one weft thread 132b, is , It is smaller than the second area A2, which is the area of the opening surface of the opening 132c.

As described above, in the detection electrode 112, the amount of deformation due to the opening can be secured more than in the case where the first area 112d is larger than the second area A2, so that the elongation rate of the detection electrode 112 due to tension can be secured. .. Therefore, in this capacitance sensor 100, the occurrence of cracks in the detection electrode 112 can be more reliably suppressed.

Further, the capacitance sensor 100 in the present embodiment further includes a control circuit 121 that is electrically connected to the detection electrode 112. Further, the detection electrode 112 is arranged on the steering wheel 3 and detects the contact between the human body and the steering wheel 3. Then, the control circuit 121 is electrically connected to the detection electrode 112, and the detection electrode 112 detects the contact between the human body and the steering wheel 3.

By electrically connecting the control circuit 121 to the detection electrode 112 in this way, it is possible to detect contact or grip with the steering wheel 3.

Further, in the capacitance sensor 100 according to another aspect of the present disclosure, the openings 132c are regularly arranged in substantially the same shape along the longitudinal direction of the warp threads 132a and the longitudinal direction of the weft threads 132b.

In this way, when the capacitance sensor 100 is pulled and stretched and then wound around the steering wheel 3, tensile stress and partial compressive stress act on the respective openings 132c, so that the respective openings 132c are substantially regular. Change. Therefore, the stress applied to the contact points P of the warp threads 132a and the weft threads 132b is also substantially equal, so that the occurrence of cracks in the detection electrode 112 can be suppressed more reliably.

(Embodiment 2)
<Configuration: Capacitance sensor 100a>
FIG. 12 is a cross-sectional view showing the rim 31 around which the steering cover 110 is wound and the steering cover 110 in line AA of FIG. 1, and a partially enlarged cross-sectional view of the rim 31, the steering cover 110, and the rim 31.

As shown in FIG. 12, the rim 31 is a grip portion for being gripped by a user (person)'s hand and has a ring shape. The rim 31 has a core metal 31b, which is a metal annular core, and a resin layer 31a that covers the core metal 31b. A steering cover 110 is wound around the rim 31.

FIG. 13 is a block diagram showing the configuration of the capacitance sensor 100a according to the second embodiment.

As shown in FIGS. 12 and 13, the capacitance sensor 100a includes a surface layer portion 111, a moisture-proof layer 115, a pair of detection electrodes 112, a base material 113, a ground electrode 114, and a control device 120. ing. Further, the capacitance sensor 100a is provided with an adhesive 116a, a first adhesive layer 116b, a second adhesive layer 116c, and a third adhesive layer 116d. The adhesive 116a, the first adhesive layer 116b, the second adhesive layer 116c, and the third adhesive layer 116d may or may not be included in the constituent requirements of the capacitance sensor 100a.

The moisture-proof layer 115 is, for example, a sheet or film having a moisture-proof and corrosion-proof film. For example, the moisture-proof layer 115 is a non-metal and is a resin such as polyvinylidene chloride. The moisture permeability of the moisture-proof layer 115 is lower than the moisture permeability of the first adhesive layer 116b and the moisture permeability of the second adhesive layer 116c. Further, in the present embodiment, the moisture-proof layer 115 is referred to as a moisture-proof layer having a moisture permeability of about 1/40 or less of that of the surface layer portion 111.

The moisture-proof layer 115 is arranged on the back surface side of the surface layer portion 111 and on the front surface side of the base material 113. That is, the moisture-proof layer 115 is arranged between the surface layer portion 111 and the base material 113. More specifically, the moisture-proof layer 115 is attached to the back surface side of the surface layer portion 111 by the third adhesive layer 116d, and is arranged on the back surface side of the surface layer portion 111. A third adhesive layer 116d is adhered to the surface of the moisture-proof layer 115, and a first adhesive layer 116b is adhered to the back surface of the moisture-proof layer 115. That is, the moisture-proof layer 115 is sandwiched between the first adhesive layer 116b and the third adhesive layer 116d.

FIG. 14 is a plan view of the surface layer portion 111, the third adhesive layer 116d, the moisture-proof layer 115, the first adhesive layer 116b, the detection electrode 112, the second adhesive layer 116c, and the base material 113 when viewed in an overlapping manner. .. FIG. 15 is a cross-sectional view of an edge portion of the steering cover 110 on the line BB of FIG. In FIG. 15, the surface layer portion 111 is omitted.

As shown in FIGS. 14 and 15, when the moisture-proof layer 115, the first adhesive layer 116b, and the third adhesive layer 116d are overlapped, the moisture-proof layer 115 is the first adhesive layer 116b and the third adhesive layer. It is covered and sealed by 116d. The surface of the moisture-proof layer 115 is a surface arranged toward the back surface of the surface layer portion 111 via the third adhesive layer 116d.

The thickness of the moisture-proof layer 115 is smaller than the thickness of the first adhesive layer 116b and the thickness of the second adhesive layer 116c. In the present embodiment, the thickness of the moisture-proof layer 115 is, for example, about 1/10 of the thickness of the first adhesive layer 116b and, for example, about 1/10 of the thickness of the second adhesive layer 116c. Further, in the present embodiment, the thickness of the moisture-proof layer 115 may be thinner than the thickness of the third adhesive layer 116d. In this case as well, the thickness of the moisture-proof layer 115 may be, for example, about 1/10 of the thickness of the third adhesive layer 116d.

Further, when the moisture-proof layer 115, the third adhesive layer 116d, and the surface layer portion 111 are viewed in an overlapping manner, the moisture-proof layer 115 is in a state of being covered with the third adhesive layer 116d. In this case, the surface area of the moisture-proof layer 115 is smaller than the surface area of the third adhesive layer 116d.

The third adhesive layer 116d is a layer that adheres the front surface of the moisture-proof layer 115 and the back surface of the surface layer portion 111, and is sandwiched between the moisture-proof layer 115 and the surface layer portion 111. The periphery of the third adhesive layer 116d is attached to the first adhesive layer 116b and the second adhesive layer 116c. That is, when the first adhesive layer 116b, the second adhesive layer 116c, and the third adhesive layer 116d are viewed in an overlapping manner, the third adhesive layer 116d is covered with the first adhesive layer 116b and the second adhesive layer 116c. It is in a state. In this case, the surface area of the third adhesive layer 116d is equal to the surface area of the first adhesive layer 116b and the surface area of the second adhesive layer 116c, or smaller than the surface area of the first adhesive layer 116b and the surface area of the second adhesive layer 116c. Each of the first adhesive layer 116b, the second adhesive layer 116c, and the third adhesive layer 116d is, for example, an adhesive, double-sided tape, or the like. Further, an acrylic pressure-sensitive adhesive may be used for the third pressure-sensitive adhesive layer 116d.

The base material 113 may have a single detection electrode 112 or a plurality of detection electrodes 112. Further, the numbers of the detection electrodes 112 and the ground electrodes 114 do not necessarily have to match. FIG. 13 illustrates a case where the pair of detection electrodes 112 and the pair of ground electrodes 114 are provided, and the description will be described below with reference to this figure.

The pair of detection electrodes 112 are arranged on the back surface side of the moisture-proof layer 115 and on the front surface side of the base material 113. That is, the pair of detection electrodes 112 are arranged between the moisture-proof layer 115 and the base material 113. More specifically, the pair of detection electrodes 112 are attached to the back surface of the moisture-proof layer 115 by the first adhesive layer 116b and are arranged on the back surface side of the moisture-proof layer 115. Further, the first adhesive layer 116b is adhered to the front surface of the pair of detection electrodes 112, and the second adhesive layer 116c is adhered to the back surface of the pair of detection electrodes 112. That is, the pair of detection electrodes 112 are sandwiched between the first adhesive layer 116b and the second adhesive layer 116c. The surface of the pair of detection electrodes 112 is a surface arranged toward the back surface of the moisture-proof layer 115 via the first adhesive layer 116b.

When the pair of detection electrodes 112, the moisture-proof layer 115, and the base material 113 are viewed in an overlapping manner, the surface area of the pair of detection electrodes 112 (total surface area of the two) is the surface area of the moisture-proof layer 115 and the base material. It is smaller than the surface area of 113. That is, the detection electrode 112 is covered with the moisture-proof layer 115, the base material 113, the first adhesive layer 116b, the second adhesive layer 116c, and the third adhesive layer 116d.

One of the detection electrodes 112 of the pair of detection electrodes 112 is arranged on one side when the capacitance sensor 100a is wound around the rim 31 (for example, the right side when viewed in a state facing the rim 31). The other detection electrode 112 is arranged on the other side when the capacitance sensor 100a is wound around the rim 31 (for example, the left side when viewed in a state facing the rim 31).

Further, the base material 113 is arranged on the side opposite to the moisture-proof layer 115 side of the detection electrode 112, and is arranged on the surface of the ground electrode 114 on the detection electrode 112 side. That is, the base material 113 is arranged between the detection electrode 112 and the ground electrode 114. More specifically, the base material 113 is attached to the back surface of the detection electrode 112 by the second adhesive layer 116c and is arranged on the back surface side of the detection electrode 112. A second adhesive layer 116c is adhered to the surface of the base material 113, and a ground electrode 114 is arranged on the back surface of the base material 113. That is, the base material 113 is sandwiched between the second adhesive layer 116c and the ground electrode 114. Further, when the base material 113 and the second adhesive layer 116c are viewed in an overlapping manner, the base material 113 is covered with the second adhesive layer 116c. The surface of the base material 113 is a surface arranged toward the back surface of the detection electrode 112 via the second adhesive layer 116c.

The ground electrode 114 is a metal wire (conductive wire) such as a copper wire. The ground electrode 114 is electrically connected to the control device 120 via the wirings 119b and 119c, and the wiring 119c is grounded.

The control circuit 121 has a sensor circuit that detects a hand contact with the steering wheel 3. The control circuit 121 is electrically connected to one of the detection electrodes 112. Further, the control circuit 121 is electrically connected to the other detection electrode 112. That is, the control circuit 121 applies an alternating current to the detection electrode 112 on one side via the wiring 119a, that is, applies a measurement potential to the detection electrode 112 on one side. Further, the control circuit 121 applies an alternating current to the detection electrode 112 on the other side via the wiring 119a, that is, applies a measurement potential to the detection electrode 112 on the other side. The control circuit 121 is electrically connected to the detection electrode 112 by wiring 119a. That is, the control circuit 121 applies an alternating current to the detection electrode 112 on the other side via the wiring 119a, that is, applies a measurement potential to the detection electrode 112 on the other side.

When the control circuit 121 does not detect contact even though the vehicle 1 is being driven, the control circuit 121 may cause the alerting device to alert the driver. For example, a warning device such as a speaker may call attention to the driver by a warning sound or voice. In addition, the display device may display a warning message urging the driver to firmly grasp the steering wheel 3.

<Effect>
As described above, the capacitance sensor 100a according to the present embodiment further includes a surface layer portion 111 to be touched by a hand and a moisture-proof layer 115 arranged on the back surface side of the surface layer portion 111, and the detection electrode 112 is provided. , The moisture-proof layer 115 is arranged on the side opposite to the surface layer portion 111 side, and the base material 113 is arranged on the side opposite to the moisture-proof layer 115 side of the detection electrode 112, and the moisture-proof layer 115 and the detection electrode 112 Is attached by the first adhesive layer 116b, the detection electrode 112 and the base material 113 are attached by the second adhesive layer 116c, and the moisture permeability of the moisture-proof layer 115 is the moisture permeability of the first adhesive layer 116b and the first. 2 It is lower than the moisture permeability of the adhesive layer 116c.

For example, when the user's hand touches the surface layer portion, the moisture such as sweat generated by the user's hand (for example, water vapor) is mixed with the residue contained in the material of the surface layer portion and becomes acidic corrosive water. Sometimes. Such corrosive water may permeate the inside of the capacitance sensor and reach the detection electrode. In this case, the detection electrode may be corroded by the corroded water.

However, according to the present embodiment, the moisture-proof layer 115 is arranged on the back surface side of the surface layer portion 111 and on the surface layer portion 111 side of the detection electrode 112. That is, the moisture-proof layer 115 is arranged outside the detection electrode 112. Further, the moisture permeability of the moisture-proof layer 115 is lower than the moisture permeability of the first adhesive layer 116b and the moisture permeability of the second adhesive layer 116c. Therefore, when the user's hand touches the surface layer portion 111, even if the surface layer portion 111 is in a high temperature and high humidity state, the moisture provided by the user's hand reaches the detection electrode 112 in the moisture-proof layer 115. Can be suppressed.

Therefore, in this capacitance sensor 100a, corrosion of the detection electrode 112 can be suppressed.

Further, in the capacitance sensor 100a according to the present embodiment, the first adhesive layer 116b and the second adhesive layer 116c are base material-less double-sided tapes.

The capacitance sensor 100a is easier to stretch than the capacitance sensor using double-sided tape having a base material. That is, by using the base material-less double-sided tape for the capacitance sensor 100a, when the capacitance sensor 100a is pulled, the deformation of the opening 132c of the detection electrode 112 is unlikely to be excessively hindered. Therefore, it is possible to secure a constant tensile elongation rate of the capacitance sensor 100a.

Further, the moisture-proof layer 115 and the detection electrode 112 can be easily adhered, and the detection electrode 112 and the base material 113 can be easily adhered. Therefore, the workability of assembling the capacitance sensor 100a can be improved.

Further, in the capacitance sensor 100a of the present embodiment, the thickness of the moisture-proof layer 115 is thinner than the thickness of the first adhesive layer 116b and the thickness of the second adhesive layer 116c.

Therefore, the thickness of the steering cover 110 of the capacitance sensor 100a in the present embodiment is not so different from the thickness of the steering cover of the capacitance sensor without the moisture-proof layer 115. Therefore, for example, even when the capacitance sensor 100a is wound around the rim 31 of the steering wheel 3 of the vehicle 1, it is unlikely that a problem such as difficulty in winding due to an increase in the thickness of the capacitance sensor 100a will occur. Further, since the step around the moisture-proof layer 115 is also reduced, the driver's feeling of discomfort when gripping the steering wheel 3 can be reduced.

Further, in the capacitance sensor 100a of the present embodiment, when the detection electrode 112, the moisture-proof layer 115, and the base material 113 are viewed in an overlapping manner, the surface area of the detection electrode 112 is the surface area of the moisture-proof layer 115 and the surface area of the moisture-proof layer 115. Smaller than the surface area of the base material 113, the detection electrode 112 is covered with the first adhesive layer 116b and the second adhesive layer 116c.

According to this, even if the surface layer portion 111 is in a high temperature and high humidity state, the detection electrode 112 is covered in a state of being sandwiched between the first adhesive layer 116b and the second adhesive layer 116c, so that corrosive water is covered by the detection electrode 112. It becomes difficult to reach. As a result, in this capacitance sensor 100a, corrosion of the detection electrode 112 can be suppressed more reliably.

Further, in the capacitance sensor 100a of the present embodiment, the surface layer portion 111 and the moisture-proof layer 115 are attached by the third adhesive layer, and the periphery of the third adhesive layer is the first adhesive layer 116b and the second adhesive layer. It is attached to the layer 116c.

According to this, since the detection electrode 112 is in a state of being sealed by the third adhesive layer 116d, the first adhesive layer 116b, and the second adhesive layer 116c, it becomes difficult for corrosive water to reach the detection electrode 112. .. As a result, in this capacitance sensor 100a, corrosion of the detection electrode 112 can be suppressed more reliably.

Further, in the capacitance sensor 100a according to the present embodiment, a ground electrode is arranged on the side of the base material 113 opposite to the detection electrode 112 side.

For example, when the capacitance sensor 100a is wound around the steering rim 31, the distance between the ground electrode 114 and the detection electrode 112 is compared with the distance between the conductive core metal 31b included in the rim 31 and the detection electrode 112. The distance can be reduced. Therefore, the first capacitance between the ground electrode 114 and the detection electrode 112 is larger than the second capacitance between the core metal and the detection electrode 112. That is, the sum of the capacitance from the hand to the detection electrode and the capacitance from the detection electrode to the ground electrode increases the sensitivity because the contact of the hand with the surface layer is detected, and the capacitance sensor 100a is detected. The decrease in accuracy can be further suppressed.

FIG. 16A is a schematic view showing a case where the current path is conducted along the warp or weft in the detection electrode 112 of the capacitance sensor 100a according to the second embodiment. FIG. 16B is a schematic view showing a case where the current path of the detection electrode 112 of the capacitance sensor 100a according to the second embodiment is conducted depending on the contact point between the warp and the weft.

Here, for example, when the conductive cloth is composed of warp threads and weft threads, if the detection electrodes are arranged in a state of being cut along the warp threads or weft threads as shown in FIG. 16A, the current path is set to the warp threads or weft threads. Since it conducts along the line, the detection electrode can detect the contact of the hand with the surface layer portion. However, for example, when the conductive cloth is not cut along the warp and weft as shown in FIG. 16B, that is, when the detection electrode is arranged in a state of being cut in the direction intersecting the warp and weft, the warp Since the conduction depends on the contact between the warp and the weft, if the warp and the weft become difficult to conduct at the contact between the warp and the weft due to corrosion, the detection electrode can detect the contact of the hand with the surface layer. It becomes difficult.

However, in the capacitance sensor 100a of the present embodiment, since the moisture-proof layer 115 can suppress the corrosion of the detection electrode 112, it can be detected regardless of the direction in which the conductive cloth is cut and the arrangement. The electrode 112 can detect the contact of the hand with the surface layer portion 111.

Further, in the capacitance sensor 100a according to the present embodiment, the third adhesive layer 116d is a base material-less double-sided tape.

According to this, the surface layer portion 111 and the moisture-proof layer 115 can be adhered to each other without impairing the extensibility. Therefore, the workability of assembling the capacitance sensor 100a can be improved.

(Embodiment 3)
<Configuration: Capacitance sensor 100b>
FIG. 17 is a block diagram showing the configuration of the capacitance sensor 100b according to the embodiment. The shape of the detection electrode 112 in FIG. 17 is shown as circuit-equivalent, and the actual shape is shown in FIG. 18, which will be described later. As shown in FIG. 17, the capacitance sensor 100b includes a surface layer portion 111, a moisture-proof layer 115, a detection electrode 112, a base material 113, a ground electrode 114, and a control device 120.

The surface layer portion 111 may have a single detection electrode 112 on the surface of the base material 113, or may have a plurality of detection electrodes 112. Further, the numbers of the detection electrodes 112 and the ground electrodes 114 do not necessarily have to match. FIG. 17 illustrates a case where a plurality of detection electrodes 112 and a plurality of ground electrodes 114 are provided, and the description will be described below with reference to this figure.

FIG. 18 is a plan view of the surface layer portion 111, the third adhesive layer 116d, the moisture-proof layer 115, the first adhesive layer 116b, the plurality of detection electrodes 112, the second adhesive layer 116c, and the base material 113 when viewed in an overlapping manner. Is. Since the cross section of the edge portion of the steering cover 110 of FIG. 18 is the same as that of FIG. 15, it will be described with reference to FIG.

As shown in FIGS. 15 and 18, when the first adhesive layer 116b, the plurality of detection electrodes 112, and the second adhesive layer 116c are viewed in an overlapping manner, the plurality of detection electrodes 112 are the first adhesive layer 116b and the first adhesive layer 116b. It is covered and sealed by the second adhesive layer 116c. Further, when the moisture-proof layer 115, the first adhesive layer 116b and the third adhesive layer 116d are viewed in layers, the moisture-proof layer 115 is covered and sealed by the first adhesive layer 116b and the third adhesive layer 116d. There is. Here, since the periphery of the plurality of detection electrodes 112 is covered with the first adhesive layer 116b and the second adhesive layer 116c, the first leader wire 112a2, the second leader wire 112b2, and the third leader wire described later will be described later. Except for 112c2, it is surrounded by a portion (sometimes referred to as an offset region) where the first adhesive layer 116b and the second adhesive layer 116c are adhered to each other.

The plurality of detection electrodes 112 form a first metal (first metal plating) on the surface of a material in which non-metal fibers such as polyethylene terephthalate (PET) are woven, and further, a second metal (first metal) is formed on the surface of the first metal. (2 metal plating) is formed and configured.

The plurality of detection electrodes 112 are arranged on the back surface side of the surface layer portion 111 and on the front surface side of the base material 113. That is, the plurality of detection electrodes 112 are arranged between the surface layer portion 111 and the base material 113. More specifically, the plurality of detection electrodes 112 are attached to the back surface side of the surface layer portion 111 by the first adhesive layer 116b and are arranged on the back surface side of the surface layer portion 111. Further, the first adhesive layer 116b is adhered to the front surface of the plurality of detection electrodes 112, and the second adhesive layer 116c is adhered to the back surface of the plurality of detection electrodes 112. That is, the plurality of detection electrodes 112 are sandwiched between the first adhesive layer 116b and the second adhesive layer 116c. The surface of the plurality of detection electrodes 112 is a surface arranged toward the back surface of the surface layer portion 111 via the first adhesive layer 116b.

When the plurality of detection electrodes 112 and the base material 113 are viewed in an overlapping manner, the surface area of the plurality of detection electrodes 112 (total surface area of two) is smaller than the surface area of the base material 113. That is, the plurality of detection electrodes 112 are covered with the base material 113, the first adhesive layer 116b, and the second adhesive layer 116c.

The plurality of detection electrodes 112 are arranged at at least three locations in the circumferential direction of the steering wheel 3. In the present embodiment, the plurality of detection electrodes 112 are composed of a first detection electrode 112a, a second detection electrode 112b, and a third detection electrode 112c.

The first detection electrode 112a has a first electrode portion 112a1 and a pair of first leader wires 112a2. The first detection electrode 112a is an example of the first conductive cloth among the plurality of conductive cloths.

The first electrode portion 112a1 is arranged at a position close to a predetermined position on the base material 113. Here, the position where the first electrode portion 112a1 is closer to the predetermined position means that the first electrode portion 112a1 is closer than the second detection electrode 112b. In the present embodiment, the first electrode portion 112a1 is arranged counterclockwise from the vicinity of the predetermined position along the circumferential direction of the steering wheel 3.

Specifically, the first electrode portion 112a1 is arranged side by side in a direction orthogonal to the circumferential direction of the steering wheel 3 in a state of being divided into two. Specifically, the first electrode portion 112a1 is cut along the circumferential direction of the steering wheel 3 and is divided into two parts. One of the first electrode portions 112a1 and the other first electrode portion 112a1 divided into two are arranged in a direction orthogonal to the circumferential direction. One first electrode portion 112a1 and the other first electrode portion 112a1 are arranged along the circumferential direction of the steering wheel 3. Further, one of the first electrode portions 112a1 and the other first electrode portion 112a1 are arranged at a predetermined interval so as not to be directly electrically connected to each other.

One first electrode portion 112a1 is electrically connected to the control device 120 via one first leader wire 112a2. That is, one end of the first leader wire 112a2 is electrically connected to one first electrode portion 112a1, the other end is electrically connected to the other first leader wire 112a2, and the other end is electrically connected to the other first leader wire 112a2, and via a harness. Is connected to the control device 120. Further, the other first electrode portion 112a1 is electrically connected to the control device 120 via the other first leader wire 112a2. That is, one end of the other first leader wire 112a2 is electrically connected to the other first electrode portion 112a1, the other end is electrically connected to the other first leader wire 112a2, and the other end is electrically connected to the other first leader wire 112a2, and via a harness. Is connected to the control device 120. That is, by electrically connecting one first leader wire 112a2 and the other first leader wire 112a2, the signal transmitted from the two divided first electrode portions 112a1 becomes one signal. Therefore, the two first electrode portions 112a1 behave as one detection electrode.

The pair of first leader lines 112a2 are arranged at a predetermined position on the base material 113 and in the vicinity thereof. In the present embodiment, the pair of first leader lines 112a2 are arranged at locations corresponding to the spokes 32 of the steering wheel 3. That is, the position where the other end of one first leader line 112a2 and the other end of the other first leader line 112a2 are connected is near the spoke 32. The pair of first leader wires 112a2 are connected to the control device 120 via a harness arranged on the spokes 32. The first leader line 112a2 is an example of a signal extraction unit.

The second detection electrode 112b has a second electrode portion 112b1 and a second leader wire 112b2.

The second electrode portion 112b1 is arranged on the base material 113 at a position farther from a predetermined position than the first electrode portion 112a1. Specifically, the second electrode portion 112b1 is arranged at a position farther from the predetermined position than the distance from the predetermined position to the first electrode portion 112a1. Further, the second electrode portion 112b1 is arranged along the circumferential direction of the steering wheel 3, and is arranged between the first electrode portion 112a1 and the third electrode portion 112c1 described later. The second detection electrode 112b is an example of the second conductive cloth among the plurality of conductive cloths.

The second electrode portion 112b1 is electrically connected to the control device 120 via the second leader wire 112b2. That is, one end of the second leader wire 112b2 is electrically connected to the second electrode portion 112b1, and the other end is connected to the control device 120 via a harness.

The second leader wire 112b2 is a metal wire such as a copper wire coated with insulation. The second leader line 112b2 is arranged between one first electrode portion 112a1 and the other first electrode portion 112a1 and extends from the second electrode portion 112b1 to a predetermined position. That is, the second leader wire 112b2 is not electrically connected to one first electrode portion 112a1 and the other first electrode portion 112a1, and one first electrode portion 112a1 and the other first electrode portion 112a1 are connected to each other. Along the way, it extends from the second electrode portion 112b1 to a predetermined position. The second leader wire 112b2 is an example of a signal extraction portion of the second conductive cloth. The second leader wire 112b2 is not limited to a metal wire such as an insulatingly coated copper wire, and may be made of the same material as the second electrode portion 112b1.

Further, the length of the second leader wire 112b2 is longer than the length of each of the first leader wire 112a2 and the third leader wire 112c2 described later. Further, the second leader wire 112b2 is not electrically connected to the first leader wire 112a2 and the third leader wire 112c2.

The third detection electrode 112c has a third electrode portion 112c1 and a third leader wire 112c2.

The third electrode portion 112c1 is arranged in the vicinity of a predetermined position on the base material 113. In the present embodiment, the third electrode portion 112c1 is arranged clockwise from the vicinity of the predetermined position along the circumferential direction of the steering wheel 3. That is, the third electrode portion 112c1 is arranged at a position symmetrical to the first electrode portion 112a1.

The third electrode portion 112c1 is electrically connected to the control device 120 via the third leader wire 112c2. That is, one end of the third leader wire 112c2 is electrically connected to the third electrode portion 112c1, and the other end is connected to the control device 120 via a harness.

The third leader wire 112c2 is a metal wire such as a copper wire coated with insulation. The third leader line 112c2 is arranged at a predetermined position on the base material 113 and in the vicinity thereof. In the present embodiment, the third leader line 112c2 is arranged at a position corresponding to the spoke 32 of the steering wheel 3. That is, the third leader line 112c2 is arranged in the vicinity of the spoke 32. The third leader wire 112c2 is connected to the control device 120 via a harness arranged on the spoke 32. Further, the third leader wire 112c2 is arranged in the vicinity of the first leader wire 112a2 and is not electrically connected to the first leader wire 112a2.

The base material 113 is attached to the back surface of the detection electrode 112 by the second adhesive layer 116c and is arranged on the back surface side of the detection electrode 112. A second adhesive layer 116c is adhered to the surface of the base material 113, and a ground electrode 114 is arranged on the back surface of the base material 113. That is, the base material 113 is sandwiched between the second adhesive layer 116c and the ground electrode 114. Further, when the base material 113 and the second adhesive layer 116c are viewed in an overlapping manner, the base material 113 is covered with the second adhesive layer 116c. The surface of the base material 113 is a surface arranged toward the back surface of the detection electrode 112 via the second adhesive layer 116c.

In FIG. 17, the ground electrode 114 on the right side of the drawing among the plurality of ground electrodes 114 corresponds to the detection electrode 112 on the right side of the drawing, and is arranged, for example, on the right side of the drawing when the capacitance sensor 100b is wound around the rim 31. There is. Further, among the plurality of ground electrodes 114, the ground electrode 114 on the left side of the drawing corresponds to the detection electrode 112 on the left side of the drawing, and is arranged, for example, on the left side of the drawing when the capacitance sensor 100b is wound around the rim 31. Further, among the plurality of ground electrodes 114, the ground electrode 114 in the center of the drawing corresponds to the detection electrode 112 in the center of the drawing, and is arranged, for example, on the top side when the capacitance sensor 100b is wound around the rim 31.

The control circuit 121 is electrically connected to the three detection electrodes 112 by three wirings 119a, respectively. Then, the control circuit 121 passes an alternating current through the three detection electrodes 112 through the three wirings 119a, that is, applies a measurement potential to the three detection electrodes 112. When a hand comes into contact with the surface layer portion 111 of the rim 31, the capacitance of the detection electrode 112 corresponding to the contact portion changes, so that the control circuit 121 is based on the current value (measurement potential) of the current flowing through the detection electrode 112. , The change in capacitance at the detection electrode 112 is measured. In this way, the control circuit 121 can detect whether or not the hand has come into contact with the steering wheel 3 from the signal indicating the change in capacitance output from the detection electrode 112.

<Effect>
As described above, in the capacitance sensor 100b according to the present embodiment, the detection electrodes 112 are a plurality of conductive cloths arranged at at least three or more locations in the circumferential direction of the steering wheel 3, and the detection electrodes 112 of the plurality of conductive cloths. Each has an electrode portion and a signal extraction portion extending from the electrode portion to a predetermined position, and among a plurality of conductive cloths, the first detection electrode 112a closer to the predetermined position and the first detection electrode 112a from the predetermined position than the first detection electrode 112a. In the distant second detection electrode 112b, the first detection electrode 112a is arranged side by side in a direction orthogonal to the circumferential direction of the steering wheel 3 in a state of being divided into two, and the first leader line of the second detection electrode 112b. The 112a2 extends from the second electrode portion 112b1 to a predetermined position along between the two divided first detection electrodes 112a without being electrically connected to the first detection electrode 112a.

For example, in order to detect which position of the steering wheel the user's hand is touching, the detection electrodes may be arranged at a plurality of places. In this case, the signal of the detection electrode is taken out from the signal extraction unit at the predetermined position, but among the detection electrodes arranged at a plurality of locations, the detection electrode arranged at a position far away from the predetermined position is the edge of the base material. The signal extraction unit may be pulled out to a predetermined position along the line. When the plurality of detection electrodes on which the signal extraction portion arranged in this way is formed and the vicinity of the base material or the like are sewn from above the surface layer portion with sewing thread, they are usually sewn along the edge of the base material. Therefore, the stress due to sewing is applied to the signal extraction portion arranged at the edge of the base material. Since the signal extraction portion is a leader wire thinner than the width of the detection electrode, it may be damaged by this stress.

Further, the steering wheel is placed in a high temperature and high humidity state by keeping the user's hand in contact with the steering wheel. Therefore, when the user's hand touches the surface layer of the steering wheel, moisture such as sweat (for example, water vapor) generated by the user's hand invades from the sewn portion and extracts a signal arranged at the edge of the base material. May reach the department. In this case, the narrow signal extraction portion has an extremely small width as compared with the detection electrode, and therefore has low corrosion resistance. As a result, when corrosion occurs, the capacitance sensor is likely to malfunction.

However, according to the present disclosure, the pair of first detection electrodes 112a divided into two are arranged side by side in a direction orthogonal to the circumferential direction of the steering wheel 3. Further, the second leader line 112b2 of the second detection electrode 112b located at a position farther than the pair of first detection electrodes 112a divided into two from the predetermined position is along the space between the pair of first detection electrodes 112a divided into two. Is placed. That is, since the second leader line 112b2 is sandwiched between the pair of first detection electrodes 112a divided into two and arranged in the central portion of the base material 113, it is difficult for stress due to sewing to be applied to the second leader line 112b2.

Further, since the second leader wire 112b2 is arranged at a position away from the sewn position (sewing thread), even if moisture such as sweat generated by the user's hand invades from the sewn portion, it corrodes. It becomes difficult to do.

Therefore, in this capacitance sensor 100b, damage and corrosion of the second leader wire 112b2 can be suppressed.

Further, in the capacitance sensor 100b of the present embodiment, the detection electrode 112 is sandwiched between the first adhesive layer 116b and the second adhesive layer 116c. Therefore, it becomes difficult for water to reach the detection electrode 112. As a result, in this capacitance sensor 100b, corrosion of the detection electrode 112 can be further suppressed.

Further, the second leader wire 112b2 formed on the second detection electrode 112b is sandwiched between the first adhesive layer 116b and the second adhesive layer 116c and fixed to the first adhesive layer 116b and the second adhesive layer 116c. Therefore, when the capacitance sensor 100b is wound around the rim 31 of the steering wheel 3, the second leader wire 112b2 is less likely to be damaged. Therefore, the second detection electrode 112b can reliably detect the contact of the hand with the surface layer portion 111.

Further, in the capacitance sensor 100b according to another aspect of the present disclosure, when the plurality of conductive cloths, the surface layer portion 111, and the base material 113 are viewed in an overlapping manner, the total surface area of the plurality of conductive cloths is the surface area. Smaller than the surface area of the portion 111 and the surface area of the base material 113, the plurality of conductive cloths are covered with the first adhesive layer 116b and the second adhesive layer 116c.

According to this, even if the surface layer portion 111 is in a high temperature and high humidity state, the detection electrode 112 is covered in a state of being sandwiched between the first adhesive layer 116b and the second adhesive layer 116c, so that moisture is absorbed in the detection electrode 112. , More difficult to reach. As a result, in this capacitance sensor 100b, corrosion of the detection electrode 112 can be suppressed more reliably.

Further, in the capacitance sensor 100b according to the present embodiment, the ground electrode 114 is arranged on the side of the base material 113 opposite to the detection electrode 112 side.

For example, when the capacitance sensor is wound around the rim of the steering wheel, in the present embodiment, the distance between the ground electrode 114 and the detection electrode 112 is compared with the distance between the conductive core metal included in the rim and the detection electrode. The distance can be reduced. Therefore, the first capacitance between the ground electrode 114 and the detection electrode 112 is larger than the second capacitance between the core metal 31b and the detection electrode 112. That is, the sum of the capacitance from the hand to the detection electrode 112 and the capacitance from the detection electrode 112 to the ground electrode 114 increases the sensitivity because the contact of the hand with the surface layer portion 111 is detected, and the capacitance increases. The decrease in the detection accuracy of the sensor 100b can be further suppressed.

(Other variants)
The capacitance sensor according to the present disclosure has been described above based on each of the above embodiments, but the present disclosure is not limited to these embodiments. As long as it does not deviate from the purpose of the present disclosure, various modifications that can be conceived by those skilled in the art may be included in the scope of the present disclosure.

For example, in the capacitance sensor according to each of the above embodiments, the steering cover has three detection electrodes and three ground electrodes, but has two or less or four or more detection electrodes and two or less or four. It may have one or more ground electrodes. For example, four detection electrodes are arranged on one base material to increase the gripping position detection resolution of the steering wheel, while only two ground electrodes are provided on the same base material to simplify the configuration of the ground electrodes. It may be changed. Further, the numbers of the detection electrodes and the ground electrodes do not necessarily have to match.

For example, in the capacitance sensor according to each of the above embodiments, the steering cover has two detection electrodes and two ground electrodes, but has one or three or more detection electrodes and one or three or more detection electrodes. It may have a ground electrode of. Further, the number of detection electrodes and the number of ground electrodes do not have to be the same, and for example, the number of detection electrodes may be four and the number of ground electrodes may be two. In this case, the ground electrode may be configured to include, for example, two detection electrodes when viewed from the thickness direction of the base material.

Further, in the capacitance sensor in each of the above embodiments, the ground electrode is fixed to the base material by being sewn to the base material, but may be fixed to the base material by another method. ..

For example, in the capacitance sensor in each of the above embodiments, the detection electrodes 112 are arranged at three places, but they may be arranged at more places. Specifically, when the detection electrodes 112 are arranged at four locations, the first detection electrode 112a and the second detection electrode 112b are arranged so as to be symmetrical with respect to a predetermined position where the signal extraction portion of FIG. 18 is concentrated. It may be arranged on the left side of FIG.

In addition, it is realized by arbitrarily combining the components and functions in each embodiment within the range obtained by applying various modifications that can be conceived by those skilled in the art to each of the above embodiments and the purpose of the present disclosure. The form to be used is also included in the present disclosure.

The capacitance sensor of the present disclosure can be applied to, for example, a steering wheel of a vehicle, a grip of a motorcycle, or the like.

3 Steering wheel 100, 100a, 100b Capacitance sensor 111 Surface layer 112 Detection electrode 112a First detection electrode (first conductive cloth)
112a2 1st leader line (signal extraction section)
112b 2nd detection electrode (2nd conductive cloth)
112b2 2nd leader line (signal extraction section)
112c 3rd detection electrode (3rd conductive cloth)
112c2 3rd leader line (signal extraction section)
113 Base material 113a Front surface 113b Back surface 114 Ground electrode 115 Moisture-proof layer 116b First adhesive layer 116c Second adhesive layer 116d Third adhesive layer 121 Control circuit 132a Warp thread 132b Weft thread 132c Opening

Claims (19)

A sheet-like base material having a front surface and a back surface,
A capacitance type detection electrode arranged on the surface of the base material is provided.
The detection electrode is
It has a plurality of warp yarns that are stranded wires and a plurality of weft yarns that are stranded wires.
A mesh cloth woven with the plurality of warp threads and the plurality of weft threads and having an opening formed by two adjacent warp threads of the plurality of warp threads and two adjacent weft threads of the plurality of weft threads. It is a conductive cloth with metal plating.
The cross section when the one warp is cut on a plane orthogonal to the longitudinal direction of one of the plurality of warp threads, or the plane orthogonal to the longitudinal direction of one weft of the plurality of weft threads. A capacitance sensor in which the area defined by the maximum outer diameter of the one warp or the one weft in the cross section when one weft is cut is smaller than the area of the opening surface of the opening. The detection electrode is adhered to the surface of the base material and fixed to the base material.
The capacitance sensor according to claim 1, wherein the elongation rate of the detection electrode when only the detection electrode is pulled is larger than the elongation rate of the base material when only the base material is pulled. The static electricity according to claim 1 or 2, wherein the pulling direction when pulling the detection electrode is a direction in which an acute angle is approximately 45 ° with respect to the longitudinal direction of each of the plurality of warp threads and the plurality of weft threads. Capacitive sensor. The pulling direction when pulling the base material is a direction in which an acute angle is approximately 45 ° with respect to the longitudinal direction of each of the plurality of warp threads and the plurality of weft threads.
The capacitance sensor according to any one of claims 1 to 3, wherein the base material is fixed to the equipment in a pulled state. The capacitance sensor according to any one of claims 1 to 4, wherein the metal plating is formed by further plating an electroless nickel plating on a surface of the mesh cloth plated with electroless copper. The capacitance sensor according to any one of claims 1 to 5, wherein the maximum width of the opening is smaller than the width of a finger of a human body. When the detection electrode is viewed in a plan view, the first area, which is the area of overlap at each contact point between the one warp and the one weft, is smaller than the second area, which is the area of the opening surface of the opening. The capacitance sensor according to any one of claims 1 to 6. Further, a control circuit electrically connected to the detection electrode is provided.
The detection electrode is
Placed on the steering wheel,
Detecting the contact between the human body and the steering wheel,
The capacitance sensor according to any one of claims 1 to 7, wherein the control circuit is electrically connected to the detection electrode, and the detection electrode detects contact between the human body and the steering wheel. The capacitance sensor according to any one of claims 1 to 8, wherein the openings are regularly arranged in substantially the same shape along the longitudinal direction of the warp and the longitudinal direction of the weft. In addition, the surface layer that you can touch,
A moisture-proof layer arranged on the back surface side of the surface layer portion is provided.
The detection electrode is arranged on the side of the moisture-proof layer opposite to the surface layer portion side.
The base material is arranged on the side of the detection electrode opposite to the moisture-proof layer side.
The moisture-proof layer and the detection electrode are attached by a first adhesive layer.
The detection electrode and the base material are attached by a second adhesive layer.
The capacitance sensor according to any one of claims 1 to 9, wherein the moisture permeability of the moisture-proof layer is lower than the moisture permeability of the first adhesive layer and the moisture permeability of the second adhesive layer. The capacitance sensor according to claim 10, wherein the first adhesive layer and the second adhesive layer are base material-less double-sided tapes. The capacitance sensor according to claim 10, wherein the thickness of the moisture-proof layer is smaller than the thickness of the first adhesive layer and the thickness of the second adhesive layer. When the detection electrode, the moisture-proof layer, and the base material are overlapped, the surface area of the detection electrode is smaller than the surface area of the moisture-proof layer and the surface area of the base material.
The capacitance sensor according to claim 12, wherein the detection electrode is covered with the first adhesive layer and the second adhesive layer. The surface layer portion and the moisture-proof layer are attached by a third adhesive layer.
The capacitance sensor according to claim 13, wherein the periphery of the third adhesive layer is attached to the first adhesive layer and the second adhesive layer. The capacitance sensor according to claim 14, wherein the third adhesive layer is a base material-less double-sided tape. The detection electrodes are a plurality of conductive cloths arranged at at least three places in the circumferential direction of the steering wheel.
Each of the plurality of conductive cloths has an electrode portion and a signal extraction portion extending from the electrode portion to a predetermined position.
Among the plurality of conductive cloths, in the first conductive cloth closer to the predetermined position and the second conductive cloth farther from the predetermined position than the first conductive cloth,
The first conductive cloth is arranged in a direction orthogonal to the circumferential direction of the steering wheel in a state of being divided into two.
The signal extraction portion of the second conductive cloth is not electrically connected to the first conductive cloth, but is formed between the first conductive cloth divided into two from the electrode portion of the second conductive cloth. The capacitance sensor according to any one of claims 10 to 15, which extends to a predetermined position. When the plurality of conductive cloths, the surface layer portion, and the base material are overlapped, the total surface area of the plurality of conductive cloths is smaller than the surface area of the surface layer portion and the surface area of the base material.
The capacitance sensor according to claim 16, wherein the plurality of conductive cloths are covered with the first adhesive layer and the second adhesive layer. The capacitance sensor according to any one of claims 1 to 17, wherein a ground electrode is arranged on the side of the base material opposite to the detection electrode side. It has a plurality of warp yarns that are stranded wires and a plurality of weft yarns that are stranded wires.
A mesh cloth woven with the plurality of warp threads and the plurality of weft threads and having an opening formed by two adjacent warp threads of the plurality of warp threads and two adjacent weft threads of the plurality of weft threads. In the first step of electroless plating,
The second step of electroplating the mesh cloth subjected to the electroless plating in the first step to generate a detection electrode, and
It has a third step of arranging the detection electrode on the surface of a sheet-shaped base material, and has
The cross section when the one warp is cut on a plane orthogonal to the longitudinal direction of one of the plurality of warp threads, or the plane orthogonal to the longitudinal direction of one weft of the plurality of weft threads. A method for manufacturing a capacitance sensor in which the area defined by the maximum outer diameter of the one warp or the one weft in the cross section when one weft is cut is smaller than the area of the opening surface of the opening.

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