Elastomer sheet and capacitive sensor

Abstract

To provide an elastomer sheet and an electrostatic sensor which improve the efficiency of a winding work.SOLUTION: An elastomer sheet 21 made of elastomer and wound around a ring portion 12 having a three-dimensional curved surface, includes: a center region 30 located at the center of the elastomer sheet 21 in a winding direction Y; and a pair of end regions 31 located at ends of the elastomer sheet 21 in the winding direction Y. The center region 30 and the pair of end regions 31 have cross-sectional shapes in an intersecting direction X intersecting with the winding direction Y in the elastomer sheet 21 formed in waveform shapes which can be extended or compressed in the intersecting direction X. The elastomer sheet 21 is configured in such a way that a rate that the center region 30 is extended or compressed and a rate that the pair of end regions 31 are extended or compressed are different from each other for the intersecting direction X.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an elastomer sheet and an electrostatic sensor. [Background technology]

[0002] Patent Document 1 discloses a technique for wrapping a sheet around a wrapping target member having a three-dimensional curved surface, in which the wrapping target member is a steering wheel.

[0003] When wrapping a sheet around a wrapping target member having a three-dimensional curved surface, there is a concern that relatively large wrinkles may occur unevenly in the sheet. This is because a three-dimensional curved surface is not a curved surface that can be unfolded into a flat surface without stretching or contracting. Therefore, when a flat sheet is wrapped around a three-dimensional curved surface, there will be portions of the sheet where the perimeter of the sheet differs. In the technology described in Patent Document 1, a slit is formed in the portion of a stretchable sheet that is to be wrapped around the inner periphery of a steering wheel, allowing the slit to absorb the difference in periphery. This is expected to suppress the occurrence of wrinkles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-16790 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with the above-mentioned techniques, it is difficult to wrap the sheet around the curved surface of the target object. This is because the sheet is stretched while being wrapped around the outer periphery of the steering wheel, while the sheet is compressed while being wrapped around the inner periphery of the steering wheel to accommodate the difference in circumferential length using cuts. Thus, when wrapping a single sheet around the target object while preventing wrinkles, it is extremely cumbersome to stretch the sheet in some areas and compress it in other areas. For this reason, there is a need for a more efficient sheet wrapping process.

[0006] The present invention has been made in view of the above background, and aims to provide an elastomer sheet and an electrostatic sensor with improved winding efficiency. [Means for solving the problem]

[0007] One aspect of the present invention is An elastomer sheet made of an elastomer that is wound around a target member having a three-dimensional curved surface, a central region located at the center of the winding direction of the elastomer sheet; a pair of end regions located at ends of the elastomer sheet in the winding direction, the central region and the pair of end regions have cross-sectional shapes in a transverse direction intersecting the winding direction of the elastomer sheet that are formed into a wave shape that can be stretched or compressed in the transverse direction, The elastomer sheet is configured such that the rate at which the central region stretches or compresses differs from the rate at which the pair of end regions stretch or compress in the cross direction.

[0008] Another aspect of the present invention is a capacitive sensor using the above-mentioned elastomer sheet. [Effects of the Invention]

[0009] According to one aspect of the present invention, an elastomer sheet is formed with a corrugated shape. By deforming the corrugated shape to broaden its wavelength, the elastomer sheet can be stretched more easily than by stretching the elastomer sheet itself. Similarly, by deforming the corrugated shape to narrow its wavelength, the elastomer sheet can be compressed more easily than by compressing the elastomer sheet itself. The corrugated shape is configured so that the rate at which the central region of the elastomer sheet stretches or compresses differs from the rate at which the two end regions stretch or compress. This allows the stretching or compression rates of the central region and the two end regions of the elastomer sheet to be changed by simply widening or narrowing the pre-formed corrugated shape. As a result, the efficiency of the elastomer sheet winding process can be improved.

[0010] According to another aspect of the present invention, the elastomer sheet of the present invention can be applied to an electrostatic sensor, thereby improving the efficiency of the work of winding the electrostatic sensor around an object to be wound.

[0011] As described above, according to this embodiment, it is possible to provide an elastomer sheet and an electrostatic sensor with improved winding efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a front view showing a steering wheel according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 1 is a plan view showing an electrostatic sensor according to a first embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 1 is a plan view showing an elastomer sheet of a first embodiment. [Figure 6] 1 is a partially enlarged plan view showing the elastomer sheet of Embodiment 1. FIG. [Figure 7]FIG. 7 is a cross-sectional view taken along the line AA to GG in FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 2. [Figure 9] FIG. 6 is a partially enlarged plan view showing the elastomer sheet of the second embodiment. [Figure 10] 8 is a cross-sectional view corresponding to line VIII-VIII in FIG. 2 in the second embodiment. [Figure 11] FIG. 10 is a partially enlarged plan view showing the elastomer sheet of embodiment 3. [Figure 12] 8 is a cross-sectional view corresponding to line VIII-VIII in FIG. 2 in a third embodiment. [Figure 13] FIG. 10 is a cross-sectional view showing an end region of an elastomer sheet according to a fourth embodiment. [Figure 14] FIG. 2 is a cross-sectional view corresponding to line II-II in FIG. 1 in a fifth embodiment. [Figure 15] FIG. 10 is a cross-sectional view showing the electrostatic sensor of the sixth embodiment. [Figure 16] FIG. 13 is a plan view showing the electrostatic sensor of the seventh embodiment. [Figure 17] FIG. 13 is a cross-sectional view showing the electrostatic sensor of the seventh embodiment. [Figure 18] FIG. 10 is a front view showing a substantially D-shaped steering wheel according to another embodiment. [Figure 19] FIG. 10 is a front view showing a rectangular steering wheel according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Embodiment 1) 1.Applicability The electrostatic sensor of this embodiment may have a configuration including an elastomer sheet and an electrode layer that is a separate member from the elastomer sheet, or an elastomer sheet that includes an elastomer layer and an electrode layer. The elastomer sheet or electrostatic sensor is attached to, for example, the mounting surface of a substrate. The substrate may be any member formed from metal, resin, or other material.

[0014] In this embodiment, the mounting surface of the base material is formed into a three-dimensional shape such as a curved surface, a compound plane (a shape formed by a plurality of planes), or a compound shape of a plane and a curved surface.

[0015] The elastomer sheet is disposed on the mounting surface (surface) of the substrate. The elastomer sheet is flexible as a whole. That is, the elastomer sheet is flexible and configured to be extensible in the planar direction.

[0016] The elastomer sheet or electrostatic sensor is configured to function as a sensor by utilizing a change in electrostatic capacitance between a pair of target electrodes. The elastomer sheet or electrostatic sensor is not limited to a configuration including a pair of target electrodes, as long as it includes at least one of the pair of target electrodes. In this embodiment, the electrostatic sensor is configured to include a shield electrode.

[0017] The electrostatic sensor can be configured as, for example, a sensor that detects external pressure or the like by utilizing changes in capacitance between target electrodes, or a sensor that detects contact or proximity of a conductor having an electric potential.

[0018] When an electrostatic sensor detects a pressing force, the capacitance between the target electrodes changes as the insulator deforms due to input such as an external pressing force, vibration, or sound (hereinafter referred to as an external pressing force, etc.), and the external pressing force, etc. is detected by detecting a voltage corresponding to the capacitance between the target electrodes.

[0019] Furthermore, when the electrostatic sensor is configured as a sensor that detects contact or proximity, the capacitance between the target electrodes changes when a conductor having an electric potential contacts or approaches, and the contact or proximity of the conductor is detected by detecting a voltage corresponding to the changed capacitance between the target electrodes.

[0020] The electrostatic sensor can be applied to, for example, the surface of a pointing device such as a mouse or joystick, or the surface of a vehicle part. Examples of vehicle parts include an armrest, a door handle, a shift lever, a steering wheel, a door trim, a center trim, a center console, and a ceiling. In this embodiment, a case where the sensor is attached to a steering wheel will be described. The steering wheel is an example of a wrapping target member. In many cases, the wrapping target member is made of an inflexible material such as metal or hard resin. The electrostatic sensor can be configured to detect the state of a subject.

[0021] In this embodiment, the electrostatic sensor has a heater function, and therefore can apply heat to the subject in addition to detecting the subject's condition.

[0022] 2. Structure of steering 10 The structure of the steering wheel 10 will be described with reference to Figures 1 and 2. As shown in Figure 1, the steering wheel 10 includes a core portion 11, a ring portion 12, and a plurality of connecting portions 13, 13, 13 that connect the core portion 11 and the ring portion 12. The ring portion 12 functions as a sensor that detects contact with a human hand.

[0023] The ring portion 12 is an axial member whose central axis is a convex curve. The ring portion 12 in this embodiment is formed in a circular ring shape. In this embodiment, the circular ring shape is an example of a convex curve. The surface of the ring portion 12 farther from the center of curvature is the outer peripheral surface 14 of the ring portion 12, and the surface of the ring portion 12 closer to the center of curvature is the inner peripheral surface 15 of the ring portion 12. However, the ring portion 12 is not limited to a circular shape and can be formed in any shape. The cross-sectional shape of the ring portion 12 perpendicular to the axis is formed, for example, in a circular shape, as shown in Figure 2. Therefore, the surface of the ring portion 12 is not a single plane but has a three-dimensional curved surface over the entire surface.

[0024] The detailed configuration of the steering 10 will be described with reference to Fig. 2. In particular, the detailed configuration of the ring portion 12 will be described.

[0025] The ring portion 12 includes a core 16, a resin inner layer material 17, an elastomer sheet 21, and a skin material 18. The core 16 forms the center of the ring portion 12 and is formed in a shape corresponding to the shape of the ring portion 12. That is, the core 16 is formed in a circular ring shape and has a circular cross section perpendicular to its axis. Therefore, the surface of the core 16 is not a single flat surface but is curved over the entire surface. Here, the cross section perpendicular to its axis of the core 16 is not limited to a circular shape but can be any shape such as an elliptical shape, an egg shape, a U-shape, a C-shape, or a polygonal shape. The core 16 in this embodiment is formed from a metal such as aluminum or magnesium and is electrically conductive. Materials other than metals can also be used as the material of the core 16.

[0026] The resin inner layer material 17 covers the outer surface of the core body 16 along the entire circumference of the ring shape of the core body 16 and along the entire circumference of the circular cross section of the core body 16. In this embodiment, the cross section of the resin inner layer material 17 is circular. The resin inner layer material 17 is disposed slightly eccentrically on the radially outer periphery of the ring portion 12. If the core body 16 has a U-shaped cross section perpendicular to the axis, the resin inner layer material 17 fills not only the radially outer side of the cross section perpendicular to the axis of the core body 16 but also the U-shaped recess of the core body 16. The resin inner layer material 17 is injection molded on the outer surface of the core body 16 and directly bonded to the outer surface of the core body 16. The cross section perpendicular to the axis of the resin inner layer material 17 is not limited to a circular shape but can be any shape, such as an oval, elliptical, or polygonal shape. The resin inner layer material 17 is molded, for example, from a foamed resin. For example, a foamed urethane resin is used for the resin inner layer material 17. Note that a non-foamed resin may also be used for the resin inner layer material 17.

[0027] An elastomer sheet 21 is wrapped around the outer surface of the resin inner layer material 17. The elastomer sheet 21 constitutes the electrostatic sensor 20. The elastomer sheet 21 will be described in detail later.

[0028] The skin material 18 covers the outer surface of the elastomer sheet 21 (the surface of the elastomer sheet 21 opposite the core 16) along the entire circumference of the ring shape of the elastomer sheet 21 (the entire circumference in FIG. 1 ) and the entire circumference of the cross-sectional shape of the elastomer sheet 21 perpendicular to the axis (the entire circumference in FIG. 2 ). In other words, when the first electrode layer 25 a is exposed on the first surface side of the elastomer layer 24, the skin material 18 also functions as a covering for the first electrode layer 25 a. The skin material 18 is wrapped around the outer surface of the elastomer sheet 21 by injection molding and bonded to the outer surface of the elastomer sheet 21. The skin material 18 is molded from, for example, a urethane resin. The outer surface of the skin material 18 forms a design surface. Therefore, it is preferable to use a non-foamed urethane resin or a slightly foamed urethane resin for the skin material 18.

[0029] 3. Overall configuration of the electrostatic sensor 20 The overall configuration of the electrostatic sensor 20 of the first embodiment will be described with reference to FIGS. 3 and 4. For ease of explanation, the thickness is exaggerated in FIG. 4. Although not specifically mentioned, the thickness is also exaggerated in other drawings. The electrostatic sensor 20 includes at least an elastomer sheet 21, a heater-shield wire 22, and an insulator sheet 23 (an example of a substrate sheet). The elastomer sheet 21 includes an elastomer layer 24, a first electrode layer 25a, and a second electrode layer 25b. However, if the elastomer sheet 21 does not function as the electrostatic sensor 20, the first electrode layer 25a and the second electrode layer 25b may be omitted.

[0030] As shown in Fig. 3, the elastomer sheet 21 is formed in a long, flat shape. However, the elastomer sheet 21 is flexible and stretchable, so it can be formed into any shape. In other words, the elastomer sheet 21 shown in Fig. 3 shows its initial shape before deformation.

[0031] The first electrode layer 25a and the second electrode layer 25b are formed in the shape of flexible conductive sheets. The first electrode layer 25a corresponds to the first electrode sheet, and the second electrode layer 25b corresponds to the second electrode sheet. However, the first electrode layer 25a and the second electrode layer 25b do not have to be in the shape of sheets, and a configuration may be adopted in which a plurality of conductive members such as electric wires are formed integrally with the elastomer layer 24, so that the entire elastomer sheet 21 is formed in a sheet shape.

[0032] The elastomer layer 24 is formed, for example, containing an elastomer as a main component. Therefore, the elastomer layer 24 is flexible. In other words, the elastomer layer 24 is flexible and configured to be extensible in the planar direction. The elastomer layer 24 is formed, for example, containing a thermoplastic material, particularly a thermoplastic elastomer, as a main component. The elastomer layer 24 may be formed from a thermoplastic elastomer itself, or may be formed from an elastomer that is crosslinked by heating a thermoplastic elastomer as a raw material.

[0033] The elastomer layer 24 may also contain rubber, resin, or other materials other than thermoplastic elastomer. For example, when the elastomer layer 24 contains rubber such as ethylene-propylene rubber (EPM, EPDM), the flexibility of the elastomer layer 24 is improved. From the viewpoint of improving the flexibility of the elastomer layer 24, the elastomer layer 24 may contain a flexibility-imparting component such as a plasticizer. Furthermore, the elastomer layer 24 may be configured to contain a reaction-curable elastomer or a thermosetting elastomer as a main component.

[0034] Furthermore, a material with good thermal conductivity is suitable for the elastomer layer 24. Therefore, the elastomer layer 24 may be made of a thermoplastic elastomer with high thermal conductivity, or may contain a filler that can increase thermal conductivity.

[0035] The first electrode layer 25a and the second electrode layer 25b are arranged in the planar direction of the elastomer layer 24 on the first surface of the elastomer layer 24, i.e., on the front surface (upper surface in FIG. 4) side of the elastomer layer 24. The first electrode layer 25a and the second electrode layer 25b constitute detection electrodes. The first electrode layer 25a and the second electrode layer 25b are conductive. Furthermore, the first electrode layer 25a and the second electrode layer 25b are flexible. That is, the first electrode layer 25a and the second electrode layer 25b are flexible and configured to be extensible in the planar direction. The first electrode layer 25a and the second electrode layer 25b are formed, for example, from a conductive cloth, a conductive elastomer, a metal foil, or the like.

[0036] FIG. 4 illustrates a case where the first electrode layer 25a and the second electrode layer 25b are made of conductive cloth. A detailed description will be given of a case where the first electrode layer 25a and the second electrode layer 25b are made of conductive cloth. The conductive cloth is a woven or nonwoven fabric made of conductive fibers. Here, the conductive fibers are formed by coating the surface of flexible fibers with a conductive material. The conductive fibers are formed, for example, by plating the surface of resin fibers such as polyethylene with copper or nickel.

[0037] In this case, the first electrode layer 25a and the second electrode layer 25b are joined to the elastomer layer 24 by fusion (thermal fusion) of the elastomer layer 24 itself. Furthermore, the first electrode layer 25a and the second electrode layer 25b have a plurality of through-holes because they are made of cloth. Therefore, a portion of the elastomer layer 24 penetrates into the through-holes of the first electrode layer 25a and the second electrode layer 25b. In other words, at least a portion of the first electrode layer 25a and the second electrode layer 25b is embedded in the elastomer layer 24.

[0038] A detailed description will be given of the case where the first electrode layer 25a and the second electrode layer 25b are formed from a conductive elastomer. In this case, the first electrode layer 25a and the second electrode layer 25b are formed by using an elastomer as a base material and incorporating a conductive filler. The elastomer that is the base material of the first electrode layer 25a and the second electrode layer 25b should preferably have the same main component as the elastomer layer 24. In particular, the first electrode layer 25a and the second electrode layer 25b should preferably be formed from a thermoplastic elastomer.

[0039] However, the first electrode layer 25a and the second electrode layer 25b are formed of a material having a softening point higher than that of the elastomer layer 24. This is because the elastomer layer 24 softens before the first electrode layer 25a and the second electrode layer 25b when the first electrode layer 25a and the second electrode layer 25b are joined to the elastomer layer 24 by fusion (thermal fusion) of the elastomer layer 24 itself. As a result, the elastomer layer 24 can have a desired thickness.

[0040] Here, the first electrode layer 25a and the second electrode layer 25b are joined to the elastomer layer 24 by fusion (thermal fusion) of the elastomer layer 24 itself. Furthermore, when the first electrode layer 25a and the second electrode layer 25b are formed so that the elastomer is located on the surface layer, the first electrode layer 25a and the second electrode layer 25b are joined to the elastomer layer 24 by fusion (thermal fusion) of the first electrode layer 25a and the second electrode layer 25b themselves. In other words, the first electrode layer 25a and the second electrode layer 25b are joined to the elastomer layer 24 by mutual fusion. Note that the first electrode layer 25a and the second electrode layer 25b and the elastomer layer 24 may be joined by fusion of only one of them.

[0041] A detailed description will be given of the case where the first electrode layer 25a and the second electrode layer 25b are formed from metal foil. Similar to the conductive cloth, the metal foil preferably has a plurality of through-holes. Therefore, the first electrode layer 25a and the second electrode layer 25b are flexible and can expand in the planar direction as the through-holes deform. The metal foil may be any conductive metal material, such as copper foil or aluminum foil. Furthermore, similar to the case of the conductive cloth, the first electrode layer 25a and the second electrode layer 25b are joined to the elastomer sheet 21 by fusion (thermal fusion) of the elastomer layer 24 itself.

[0042] One heater / shield wire 22 is disposed on the second surface of the elastomer layer 24, i.e., on the back surface (bottom surface in FIG. 4 ) of the elastomer layer 24. In FIG. 3 , the heater / shield wire 22 is illustrated as a plane for convenience, but is actually wired within the area illustrated as a plane. The heater / shield wire 22 is configured to function as both a heater wire and a shield electrode wire. The heater / shield wire 22 is formed to have thermal resistance in order to function as a heater wire. Furthermore, the heater / shield wire 22 is configured to function as a shield electrode when a predetermined voltage is applied.

[0043] 4, the heater-shield wire 22 is configured to include, for example, a conductive wire 22a and a conductive wire coating material 22b that coats the conductive wire 22a. In order to provide thermal resistance, the conductive wire 22a includes, for example, a core wire and a circumferential wire wound spirally around the core wire. However, the conductive wire 22a is not limited to this configuration, and may have both electrical conductivity and thermal resistance.

[0044] Furthermore, heater-shield wire 22 is flexible. That is, heater-shield wire 22 is flexible and configured to be extensible in the planar direction. Heater-shield wire 22 is formed from, for example, conductive cloth, conductive elastomer, metal foil, or the like.

[0045] In this embodiment, a portion of the heater / shield wire 22 is disposed in contact with the elastomer layer 24. A portion of the heater / shield wire 22 may be embedded in the elastomer layer 24. Therefore, the heater / shield wire 22 can directly transfer heat to the elastomer layer 24.

[0046] In particular, the conductive wire coating 22b of the heater / shield wire 22 is joined to the elastomer layer 24 by fusion (thermal welding) of the elastomer layer 24 itself. Furthermore, if the conductive wire coating 22b of the heater / shield wire 22 is formed containing a thermoplastic elastomer, the heater / shield wire 22 and the elastomer layer 24 are joined by fusion (thermal welding) of the conductive wire coating 22b of the heater / shield wire 22 itself. In other words, the heater / shield wire 22 and the elastomer layer 24 are joined by mutual fusion. Note that the heater / shield wire 22 and the elastomer layer 24 may be joined by fusion of only one of them.

[0047] The heater-shield wire 22 is disposed so as to face almost the entire surfaces of the first electrode layer 25a and the second electrode layer 25b.

[0048] The insulator sheet 23 is disposed on the second surface of the elastomer layer 24, i.e., on the back surface (lower surface in FIG. 4 ) of the elastomer layer 24. Furthermore, the insulator sheet 23 is disposed on the opposite side of the heater-shield wire 22 from the first electrode layer 25a and the second electrode layer 25b. In other words, the heater-shield wire 22 is sandwiched between the insulator sheet 23 and the elastomer layer 24. In this embodiment, the insulator sheet 23 is formed in the same surface shape as the elastomer layer 24 and faces the elastomer layer 24 over its entire surface. However, the insulator sheet 23 may have a surface shape different from that of the elastomer layer 24.

[0049] The insulating sheet 23 is formed by including, for example, an elastomer as a main component. Therefore, the insulating sheet 23 is flexible. In other words, the insulating sheet 23 is flexible and is configured to be extensible in the planar direction. The insulating sheet 23 is formed by including, for example, a thermoplastic material, particularly a thermoplastic elastomer, as a main component. The insulating sheet 23 may be formed by using a thermoplastic elastomer itself, or may be formed by using a thermoplastic elastomer as a raw material and heating it to crosslink an elastomer as a main component.

[0050] Furthermore, the insulating sheet 23 may contain rubber, resin, or other materials other than thermoplastic elastomer. For example, when the insulating sheet 23 contains rubber such as ethylene-propylene rubber (EPM, EPDM), the flexibility of the insulating sheet 23 is improved. From the viewpoint of improving the flexibility of the insulating sheet 23, the insulating sheet 23 may contain a flexibility-imparting component such as a plasticizer.

[0051] The insulating sheet 23 is bonded to the second surface of the elastomer layer 24 by fusion bonding of the elastomer layer 24 itself. When the insulating sheet 23 is formed containing a thermoplastic elastomer, the elastomer layer 24 and the insulating sheet 23 are bonded by fusion bonding of the insulating sheet 23 itself.

[0052] Furthermore, the insulating sheet 23 is disposed in contact with a portion of the heater-shield wire 22. In particular, the insulating sheet 23 buries a portion of the heater-shield wire 22. The insulating sheet 23 is bonded to the conductive wire coating 22b of the heater-shield wire 22 by fusion bonding of the insulating sheet 23 itself.

[0053] 4, heater-shield wire 22 is embedded deeper in insulator sheet 23 than in elastomer layer 24. However, the embedding depths may be the same for both, or the embedding depth in elastomer layer 24 may be deeper.

[0054] When the conductive wire coating material 22b of the heater / shield wire 22 is formed to contain a thermoplastic elastomer, the heater / shield wire 22 and the insulating sheet 23 are joined by fusion (thermal fusion) of the conductive wire coating material 22b of the heater / shield wire 22 itself. In other words, the heater / shield wire 22 and the insulating sheet 23 are joined by mutual fusion. Note that the heater / shield wire 22 and the insulating sheet 23 may be joined by fusion of only one of them.

[0055] Furthermore, the insulating sheet 23 is preferably made of a material with high thermal insulation properties. That is, the insulating sheet 23 is formed so as to have a lower thermal conductivity than the elastomer layer 24. In particular, the insulating sheet 23 is preferably formed of a material containing a foamed resin, which has a lower thermal conductivity than the elastomer layer 24. The air layer in the foamed resin allows the insulating sheet 23 to exhibit high thermal insulation performance.

[0056] When the insulator sheet 23 is made of foamed resin, it is preferable that the surface facing the elastomer layer 24 be formed in an open-cell state with the cells of the foamed resin open. In this case, the insulator sheet 23 is bonded to the elastomer layer 24 by being partially impregnated with the elastomer layer 24. This increases the bonding strength between the elastomer layer 24 and the insulator sheet 23. Furthermore, the insulator sheet 23 may be bonded to the heater / shield wire 22 by being partially impregnated with the conductive wire coating material 22b of the heater / shield wire 22.

[0057] 4. Shape of elastomer sheet 21 The shape of the elastomer sheet 21 will be described with reference to Figures 5 to 8. For ease of explanation, the first electrode layer 25a, the second electrode layer 25b, the heater-shield wire 22, and the insulator sheet 23 are omitted from Figure 5. Figure 5 shows the elastomer sheet 21 in a state before it is wrapped around the steering wheel 10.

[0058] The elastomer sheet 21 is configured in a generally rectangular shape that is long in the longitudinal direction. In the following description, of the two directions perpendicular to the longitudinal direction X of the elastomer sheet 21, the direction perpendicular to the surface of the elastomer sheet 21 is referred to as the thickness direction Z, and the direction along the surface of the elastomer sheet 21 is referred to as the wrapping direction Y in which the elastomer sheet 21 is wrapped around the ring portion 12 of the steering wheel 10. The elastomer sheet 21 may have protrusions that protrude outward from the side edges. Terminals for connecting the first electrode layer 25a, the second electrode layer 25b, or the heater / shield wire 22 to an external circuit can be attached to the protrusions.

[0059] The elastomer sheet 21 is wrapped around the ring portion 12 of the steering wheel 10 in a wrapping direction Y. The longitudinal direction X of the elastomer sheet 21 is a cross direction that intersects with the wrapping direction Y. The elastomer sheet 21 has a central region 30 near the center of the wrapping direction Y, end regions 31 near a pair of edges in the wrapping direction Y, and a boundary region 32 located between the central region 30 and the end regions 31.

[0060] The central region 30 and the pair of end regions 31 are formed in a wave-like shape that can be stretched or compressed in the longitudinal direction X over the entire area in the longitudinal direction X. The wave-like shapes formed in the central region 30 and the pair of end regions 31 are formed by heating and softening the elastomer sheet 21 and then pressing it.

[0061] Fig. 7 shows cross-sectional views taken along lines AA, BB, CC, DD, EE, FF, and GG in Fig. 6. The symbols A to G correspond to the symbols of the cut surfaces of the cross-sectional views.

[0062] As shown in the cross-sectional views along lines AA, BB, and CC in Figure 7, in this embodiment, the central region 30 of the elastomer sheet 21 is formed in a wavy shape that can be stretched or compressed in the longitudinal direction X of the elastomer sheet 21 in the winding direction Y, across the entire longitudinal direction X of the elastomer sheet 21. The wavy shape formed in the central region 30 is composed of a smooth curved surface. The cross-sectional shape of the central region 30 in the longitudinal direction X before being wrapped around the steering wheel 10 is formed in a sine wave shape. A sine wave shape includes cases where the cross-sectional shape of the central region 30 coincides with a sine wave, as well as cases where the cross-sectional shape differs from a sine wave but is still recognizable as a sine wave.

[0063] As shown in the cross-sectional views along lines AA, BB, and CC in FIG. 7 , the amplitude of the waveform formed in the central region 30 of the elastomer sheet 21 is greatest at the center of the central region 30 in the winding direction Y and decreases toward the pair of end regions 31. That is, the amplitude of the waveform decreases in the order of A, B, and C. In this embodiment, the amplitude of the waveform changes continuously as it approaches the pair of end regions 31 from the center in the winding direction Y. However, the amplitude of the waveform may also decrease stepwise as it approaches the pair of end regions 31 from the center in the winding direction Y. This is effective when the curvature of the three-dimensional curved surface of the steering wheel 10 changes stepwise.

[0064] The thickness of the elastomer sheet 21 in the central region 30 is thinnest at the center in the winding direction Y and gradually becomes thinner toward the pair of end regions 31. This is because the elastomer sheet 21 is stretched by press working. The central region in the winding direction Y is stretched the most, and as a result, the thickness of the elastomer sheet 21 is smallest.

[0065] The wavelength of the waveform in the central region 30 is the same at the central position in the winding direction Y and at positions near the pair of end regions 31.

[0066] The cross-sectional view designated by the symbol D in Figure 7 is a cross-sectional view taken along line DD in Figure 6. The cross-sectional view along line DD is a cross-sectional view of a boundary region 32 located between the central region 30 and the end region 31 of the elastomer sheet 21. The boundary region 32 is flat. The thickness of the boundary region 32 may be uniform or non-uniform in the longitudinal direction X and the winding direction Y. When the elastomer sheet 21 is heated, the shape of the central region 30 may be fixed in a bent state.

[0067] As shown in the cross-sectional views taken along lines EE, FF, and GG in Fig. 7, the pair of end regions 31 have a plurality of bellows portions 33 arranged at predetermined intervals in the longitudinal direction X, and support portions 34 connecting adjacent bellows portions 33 in the longitudinal direction X. The bellows portions 33 are formed in an M-shape when viewed from the winding direction Y, with one plane bent. The M-shape is an example of a wave shape.

[0068] When the flat surfaces constituting bellows portion 33 are deformed to approach each other, bellows portion 33 is compressed in longitudinal direction X. When the flat surfaces constituting bellows portion 33 are deformed to move away from each other, bellows portion 33 is stretched in longitudinal direction X.

[0069] The length dimension of the bellows portion 33 in the longitudinal direction X is A pair of end regions 31 However, the length dimension of the bellows portion 33 in the longitudinal direction X is formed so as to continuously increase as it approaches the central region 30 of the elastomer sheet 21. A pair of end regions 31 The length dimension of the bellows portion 33 in the longitudinal direction X is made smaller as the rate of extension or compression in the longitudinal direction X is smaller, and made larger as the rate of extension or compression in the longitudinal direction X is larger.

[0070] The thickness dimension of the support portion 34 in the thickness direction Z is larger than the thickness dimension of the bellows portion 33. When the elastomer sheet 21 is press-formed, resin moves from the bellows portion 33 to the support portion 34, so that the thickness dimension of the support portion 34 is larger as the length dimension of the bellows portion 33 in the longitudinal direction X increases. Furthermore, the length dimension of the support portion 34 in the longitudinal direction X increases as the rate of stretching or compression in the longitudinal direction X decreases, and decreases as the rate of stretching or compression increases.

[0071] Figure 8 shows an enlarged cross-sectional view of a portion of the steering wheel 10 wrapped with the elastomer sheet 21. For ease of explanation, the skin material 18 has been omitted. The upper side of Figure 8 shows the outer peripheral surface 14 of the resin inner layer material 17 that constitutes the ring portion 12 of the steering wheel 10, and the lower side of Figure 8 shows the inner peripheral surface 15 of the resin inner layer material 17 that constitutes the ring portion 12.

[0072] A central region 30 of the elastomer sheet 21 is attached to the outer peripheral surface 14 of the resin inner layer material 17 that constitutes the ring portion 12. The corrugated shape of the central region 30 is stretched in the longitudinal direction X, thereby deforming into a smoothly curved shape that conforms to the outer peripheral surface 14 of the resin inner layer material 17 that constitutes the ring portion 12. This prevents large wrinkles from being formed unevenly in the central region 30 of the elastomer sheet 21.

[0073] A pair of end regions 31 of the elastomer sheet 21 are attached to the inner peripheral surface 15 of the resin inner layer material 17 that constitutes the ring portion 12. As the multiple bellows portions 33 in the pair of end regions approach each other, the pair of end regions 31 of the elastomer sheet 21 are compressed in the longitudinal direction X. As the bellows portions 33 deform, the support portions 34 adjacent to each other in the longitudinal direction X approach each other. As a result, a relatively narrow gap is formed between the adjacent support portions 34, and the deformed bellows portions 33 are accommodated in this gap. The diameter dimension of the gap formed between the support portions 34 is relatively small. Furthermore, the gaps are formed regularly and evenly between the adjacent support portions 34. This prevents large wrinkles from being formed unevenly in the pair of end regions 31 of the elastomer sheet 21.

[0074] In this embodiment, when wrapped around the resin inner layer material 17, the central region 30 of the elastomer sheet 21 is stretched by approximately 10% compared to the state before being wrapped around the resin inner layer material 17. On the other hand, when wrapped around the resin inner layer material 17, the pair of end regions 31 of the elastomer sheet 21 are compressed by approximately 10% compared to the state before being wrapped around the resin inner layer material 17. This allows the elastomer sheet 21 to accommodate the difference in circumferential length between the outer circumferential surface 14 and the inner circumferential surface 15 of the resin inner layer material 17 that constitutes the ring portion 12. However, the degree to which the elastomer sheet 21 is stretched and compressed is not particularly limited.

[0075] 2 shows a cross section of the ring portion 12 in the axis-perpendicular direction. As described above, the thickness of the central region 30 of the elastomer sheet 21 is relatively small, while the thickness of the support portions 34 formed in the pair of end regions 31 of the elastomer sheet 21 is relatively large. As a result, the thickness of the elastomer sheet 21 when wrapped around the resin inner layer material 17 differs between the outer peripheral surface 14 of the resin inner layer material 172 that constitutes the ring portion 1 and the inner peripheral surface 15 of the resin inner layer material 17 that constitutes the ring portion 12. As described above, the resin inner layer material 17 is disposed slightly eccentrically on the outer periphery side of the ring portion 12, so that when the elastomer sheet 21 is wrapped around the resin inner layer material 17, the outer shape of the elastomer sheet 21 in the axis-perpendicular direction is configured to be circular.

[0076] 5. Manufacturing method of steering wheel 10 Next, a description will be given of an example of a method for manufacturing the steering wheel 10. Note that the method for manufacturing the steering wheel 10 is not limited to the following description.

[0077] The resin inner layer material 17 is injection molded onto the outer surface of the core body 16. That is, the core body 16 is placed in an injection molding die (not shown), and a molding material is injected into the die to form the resin inner layer material 17. In this way, the core body 16 and the resin inner layer material 17 are integrated.

[0078] The elastomer layer 24, first electrode layer 25a, second electrode layer 25b, heater / shield wire 22, and insulator sheet 23 are formed into a predetermined shape. The first electrode layer 25a and second electrode layer 25b are bonded to the surface of the elastomer layer 24. This forms the elastomer sheet 21. The heater / shield wire 22 and insulator sheet 23 are bonded. The insulator sheet 23 and heater / shield wire 22 are bonded to the back surface of the elastomer sheet 21 so that the heater / shield wire 22 faces the back surface of the elastomer sheet 21. The elastomer sheet 21, heater / shield wire 22, and insulator sheet 23 are integrated to form the electrostatic sensor 20.

[0079] The electrostatic sensor 20 is heated to a temperature equal to or higher than the softening points of the elastomer layer 24 and the insulating sheet 23. Then, the electrostatic sensor 20 is pressed by a known rolling mill (not shown) to form a wave shape in the central region 30 and the pair of end regions 31 of the electrostatic sensor 20. The rolling mill has a pair of rollers, and by passing the electrostatic sensor 20 between the pair of rollers, it is possible to transfer the shape formed on the surface of the roller to the electrostatic sensor 20. That is, a shape corresponding to a sine wave shape may be formed on the surface of the roller corresponding to the central region 30 of the elastomer sheet 21, and a shape corresponding to an M-shape may be formed on the surface of the roller corresponding to the pair of end regions 31 of the elastomer sheet 21.

[0080] Next, the electrostatic sensor 20 is wound around the core 16 and the resin inner layer material 17. First, the electrostatic sensor 20 is positioned so as to face the resin inner layer material 17. Next, the central region 30 of the elastomer sheet 21 is attached to the outer peripheral surface 14 of the ring portion 12. After that, the electrostatic sensor 20 is wound around the ring portion 12 along the peripheral surface in the direction perpendicular to the axis of the ring portion 12. At this time, the central region 30 of the elastomer sheet 21 is stretched in the longitudinal direction X, and the pair of end regions 31 are compressed in the longitudinal direction X. The pair of end regions 31 are abutted against each other and are adhesively or thermally fused together.

[0081] After the electrostatic sensor 20 is wound around the entire circumference of the core body 16 and the resin inner layer material 17, the resin inner layer material 17 and the electrostatic sensor 20 are bonded or heat-sealed.

[0082] Next, the skin material 18 is formed into a predetermined shape and wrapped around the outer surface of the electrostatic sensor 20. After that, the electrostatic sensor 20 and the skin material 18 are adhered or heat-sealed together. The skin material 18 may also be formed by placing the core body 16, the resin inner layer material 17, and the electrostatic sensor 20 in an injection molding die (not shown) and injecting a molding material.

[0083] 6. Effects of the First Embodiment Next, the effects of embodiment 1 will be described. The elastomer sheet 21 of this embodiment is made of an elastomer and is wrapped around a steering wheel 10 having a three-dimensional curved surface, and includes a central region 30 located in the center of the winding direction Y of the elastomer sheet 21, and a pair of end regions 31 located at the ends of the elastomer sheet 21 in the winding direction Y, and the central region 30 and the pair of end regions 31 have cross-sectional shapes in the longitudinal direction X, which intersects with the winding direction Y, formed into corrugated shapes that can be stretched or compressed in the longitudinal direction X, and are configured so that the rate at which the central region 30 stretches or compresses in the longitudinal direction X differs from the rate at which the pair of end regions 31 stretch or compress.

[0084] The elastomer sheet 21 has a corrugated shape. By deforming the elastomer sheet 21 to widen the wavelength of the corrugated shape, the elastomer sheet 21 can be stretched more easily than by stretching the elastomer sheet 21 itself. Similarly, by deforming the elastomer sheet 21 to narrow the wavelength of the corrugated shape, the elastomer sheet 21 can be compressed more easily than by compressing the elastomer sheet 21 itself. The corrugated shape is configured so that the rate at which the central region 30 of the elastomer sheet 21 stretches or compresses differs from the rate at which the pair of end regions 31 stretch or compress. This allows the elastomer sheet 21 to have different stretch or compression rates between the central region 30 and the pair of end regions 31 by simply widening or narrowing the preformed corrugated shape. As a result, the efficiency of the winding process of the elastomer sheet 21 can be improved.

[0085] In this embodiment, one of the central region 30 and the pair of end regions 31 is configured to be stretchable, and the other is configured to be compressible.

[0086] By configuring one of the central region 30 and the pair of end regions 31 of the elastomer sheet 21 to be stretchable and the other to be compressible, the elastomer sheet 21 can be wound around a target by, for example, stretching the central region 30 and compressing the pair of end regions 31. This allows the work content to be clearly separated between the central region 30 and the pair of end regions 31 when winding the elastomer sheet 21 around the ring portion 12, thereby improving the efficiency of the winding work.

[0087] In addition, the elastomer sheet 21 of this embodiment further includes a boundary region 32 located at the boundary between the central region 30 and a pair of end regions 31 in the winding direction Y of the elastomer sheet 21, and having a cross-sectional shape in the longitudinal direction X formed into a flat plate shape before winding around the ring portion 12 of the steering wheel 10.

[0088] When one of the central region 30 and the pair of end regions 31 is stretchable and the other is compressible, a portion that is less likely to deform is formed between the central region 30 and the pair of end regions 31. This portion becomes a skeletal structure, thereby improving the strength of the elastomer sheet 21.

[0089] In this embodiment, the cross-sectional shape in the longitudinal direction X of at least one of the central region 30 and the pair of end regions 31 is formed to be wavy over the entire length in the longitudinal direction X. This makes it possible to easily form a structure that can be stretched or compressed over the entire length in the longitudinal direction X.

[0090] In this embodiment, at least one of the central region 30 and the pair of end regions 31 has a sine wave cross section in the longitudinal direction X before the ring portion 12 is wrapped around it.

[0091] When the elastomer sheet 21 is deformed to widen the wavelength of the sine wave, it deforms to approach a flat surface. In this way, applying a sine wave shape to the stretchable region of the elastomer sheet 21 is particularly effective. On the other hand, when the sine wave is deformed in a direction narrowing the wavelength, the peaks of the sine wave approach each other. This portion does not become completely flat because gaps are formed between the peaks of adjacent sine waves. However, because the sine wave shape is regular, the overall shape is flatter than when irregular wrinkles are formed. Therefore, a sine wave shape can be applied to the compressible region of the elastomer sheet 21.

[0092] In this embodiment, the amplitude of the sine wave is decreased as the stretching or compression rate in the longitudinal direction X decreases, and increased as the stretching or compression rate increases. By simply adjusting the amplitude of the sine wave, the elastomer sheet 21 can easily adapt to the stretching or compression rate.

[0093] In this embodiment, the sinusoidal amplitude is generated from the central region 30 to a pair of edge area 31 This is effective when the curvature of the three-dimensional curved surface formed on the ring portion 12 changes continuously.

[0094] In this embodiment, at least one of the central region 30 and the pair of end regions 31 has a cross-sectional shape in the longitudinal direction X that is formed to be stretchable or compressible in the longitudinal direction X, and includes a plurality of bellows portions 33 arranged at predetermined intervals in the longitudinal direction X, and support portions 34 that connect adjacent bellows portions 33 in the longitudinal direction X and are formed to be thicker than the bellows portions 33 in the winding direction Y and in a direction perpendicular to the longitudinal direction X.

[0095] When the bellows portions 33 formed in the pair of end regions 31 are compressed, the support portions 34 approach each other. As a result, the end faces of the support portions 34 as a whole form a flat surface. Meanwhile, the compressed bellows portions 33 are accommodated in the narrowed spaces between the support portions 34. As a result, the elastomer sheet 21 as a whole becomes flat. In this way, it is particularly effective to apply this embodiment to regions where the elastomer sheet 21 is compressible.

[0096] In this embodiment, the width dimension of the bellows portion 33 in the longitudinal direction X is made smaller as the rate of stretching or compression in the longitudinal direction X is smaller, and made larger as the rate of stretching or compression in the longitudinal direction X is larger, and the width dimension of the support portion 34 in the longitudinal direction X is made larger as the rate of stretching or compression in the longitudinal direction X is smaller, and made smaller as the rate of stretching or compression in the longitudinal direction X is larger.

[0097] Furthermore, by adjusting the width of the bellows portion 33 and the width of the support portion 34 in the longitudinal direction X, the degree to which the elastomer sheet 21 is stretched or compressed can be easily accommodated.

[0098] In this embodiment, the width dimension of the bellows portion 33 in the longitudinal direction X is edge area 31 The width of the support portion 34 in the longitudinal direction X is increased continuously as it approaches the pair of edge area 31 It becomes smaller continuously as it approaches .

[0099] This is effective when the curvature of the convex curved surface formed on the ring portion 12 changes continuously.

[0100] In this embodiment, the ring portion 12 is an axial member whose central axis is a convex curve, the central region 30 is located on the surface of the axial member that is farther from the center of curvature of the convex curve in the circumferential direction and is formed to be extensible in the longitudinal direction X, and the pair of end regions 31 are located on the surface of the axial member that is closer to the center of curvature of the convex curve in the circumferential direction and are formed to be compressible in the longitudinal direction X.

[0101] When the ring portion 12 is a shaft member whose central axis is a convex curve, the circumferential length of the surface of the ring portion 12 farther from the center of curvature of the convex curve in the circumferential direction becomes longer than the circumferential length of the surface closer to the center of curvature of the convex curve. This results in a difference in circumferential length between the side farther from the center of curvature of the convex curve and the side closer to the center of curvature of the convex curve. In this embodiment, the central region 30 of the elastomer sheet 21 is placed on the side of the ring portion 12 farther from the center of curvature of the convex curve, and the elastomer sheet 21 is wrapped around the side of the ring portion 12 closer to the center of curvature of the convex curve. In this case, the pair of end regions 31 of the elastomer sheet 21 are compressible, so that the difference in circumferential length between the side of the ring portion 12 farther from the center of curvature of the convex curve and the side closer to the center of curvature of the convex curve can be absorbed.

[0102] In this embodiment, the member to be wound is a circular steering wheel 10, the central region 30 being located on the outer peripheral surface of the circular steering wheel 10 and being formed to be extensible in the longitudinal direction X, and the pair of end regions 31 being located on the inner peripheral surface of the circular steering wheel 10 and being formed to be compressible in the longitudinal direction X.

[0103] When the member to be wound is annular, the circumferential length of the outer periphery becomes longer than the circumferential length of the inner periphery, resulting in a difference in circumferential length between the inner and outer peripheries. In this embodiment, the central region 30 of the elastomer sheet 21 is placed against the outer periphery of the ring portion 12, and the elastomer sheet 21 is wound toward the inner periphery of the ring portion 12. In this case, the pair of end regions 31 of the elastomer sheet 21 are compressible, so the difference in circumferential length between the outer periphery and the inner periphery of the ring portion 12 can be absorbed.

[0104] In this embodiment, the central region 30 has a cross-sectional shape in the longitudinal direction X that is formed in a wave shape over the entire length in the longitudinal direction X, and the pair of end regions 31 have cross-sectional shapes in the longitudinal direction X that are formed to be stretchable or compressible in the longitudinal direction X, and include a plurality of bellows portions 33 arranged at predetermined intervals in the longitudinal direction X, and support portions 34 that connect adjacent bellows portions 33 in the longitudinal direction X and are formed to be thicker than the bellows portions 33 in the winding direction Y and the direction perpendicular to the longitudinal direction X.

[0105] This embodiment is particularly effective when the central region 30 of the elastomer sheet 21 is set as a stretchable region and the pair of end regions 31 are set as compressible regions, for the reasons explained below.

[0106] First, when the elastomer sheet 21 is deformed so as to widen the wavelength of the corrugated shape, it deforms into a smooth curved shape that conforms to the outer peripheral surface 14 of the steering wheel 10. For this reason, it is particularly effective to apply a corrugated shape to the stretchable region of the elastomer sheet 21.

[0107] Furthermore, when the bellows portion 33 is compressed, the support portions 34 move closer to each other. As a result, the end faces of the support portions 34 form a flat surface as a whole. Meanwhile, the compressed bellows portion 33 is accommodated in the narrowed spaces between the support portions 34. As a result, the elastomer sheet 21 as a whole has a smoothly curved surface shape that conforms to the inner circumferential surface 15 of the steering wheel 10. In this way, it is particularly effective to apply this embodiment to the compressible region of the elastomer sheet 21.

[0108] In this embodiment, the elastomer sheet 21 includes an elastomer layer 24 made of an elastomer, and a first electrode layer 25a and a second electrode layer 25b disposed on a first surface of the elastomer layer 24. This allows an electrical circuit to be formed on the first surface of the elastomer sheet 21.

[0109] In this embodiment, the first electrode layer 25a and the second electrode layer 25b are arranged in parallel on the first surface of the elastomer layer 24. This allows a plurality of electrode layers 25a, 25b to be arranged in parallel on the first surface of the elastomer layer 24.

[0110] The electrostatic sensor 20 of this embodiment includes a heater sheet that is integrated with a heater / shield wire 22 that serves as both a heater wire and a shield wire and an insulator sheet 23, and is arranged on a second surface opposite to the first surface of the elastomer layer 24.

[0111] The elastomer sheet 21 can be heated by passing a current through the heater-shield wire 22. The heater-shield wire 22 also improves the electromagnetic shielding properties of the electrostatic sensor 20.

[0112] The capacitive sensor 20 of this embodiment includes a sheet-like first electrode layer 25a and a sheet-like second electrode layer 25b.

[0113] This improves the efficiency of the work of winding the electrostatic sensor 20 around the object to be wound.

[0114] In this embodiment, the electrostatic sensor 20 includes a heater sheet that is an integrated unit of a heater / shield wire 22 that serves as both a heater wire and a shield wire and an insulator sheet 23, and is arranged on a second surface opposite to the first surface of the elastomer sheet 21.

[0115] The sensor can function by utilizing the change in capacitance between the first electrode layer 25a arranged on the first surface of the elastomer sheet 21 and the heater sheet arranged on the second surface of the elastomer sheet 21. Since the heater-shield wire 22 and the base sheet are integrated, the electrostatic sensor 20 can be made thinner.

[0116] (Embodiment 2) Next, a second embodiment will be described with reference to Figs. 9 and 10. As shown in Fig. 9, an elastomer sheet 21a according to an electrostatic sensor 20a of this embodiment includes, in a central region 30a, a plurality of bellows portions 33a arranged at predetermined intervals in the longitudinal direction X, and a support portion 34a connecting adjacent bellows portions 33a in the longitudinal direction X. In the thickness direction Z, the support portion 34a is formed to be thicker than the bellows portions 33a. That is, the thickness dimension of the support portion 34a in the thickness direction Z is formed to be larger than the thickness dimension of the bellows portions 33a.

[0117] As shown in FIG. 9, when viewed from the front side of the elastomer sheet 21a, the length dimension in the longitudinal direction X of the bellows portion 33a formed in the central region 30a is formed to be largest at the center position in the winding direction Y. A pair of end regions 31 This allows the elastomer sheet 21a to be configured so that the stretch ratio of the central region 30a is greatest.

[0118] 10, in this embodiment, an elastomer sheet 21a is wrapped around the resin inner layer material 17 that constitutes the ring portion 12, and a bellows portion 33a formed in a central region 30a of the elastomer sheet 21a is attached to the outer peripheral surface 14 of the resin inner layer material 17 that constitutes the ring portion 12. The flat surfaces that constitute the bellows portion 33a are extended and spread apart from each other. Although a space is formed between the bellows portion 33a and the outer peripheral surface 14 of the resin inner layer material 17 that constitutes the ring portion 12, the space is supported by the support portion 34a, which prevents the elastomer sheet 21 from deforming.

[0119] The configuration other than that described above is substantially the same as that of the first embodiment, so the same members are given the same reference numerals and redundant explanations will be omitted.

[0120] In this embodiment, the central region 30a and the pair of end regions 31a are each provided with a plurality of bellows portions 33, 33a whose cross-sectional shapes in the longitudinal direction X are formed so as to be stretchable or compressible in the longitudinal direction X, and support portions 34, 34a which connect adjacent bellows portions 33, 33a in the longitudinal direction X and which are formed to be thicker than the bellows portions 33, 33a in the winding direction Y and in a direction perpendicular to the longitudinal direction X.

[0121] When the bellows portion 33 is compressed, the support portions 34 move closer to each other. As a result, the end faces of the support portions 34 form a flat surface as a whole. Meanwhile, the compressed bellows portion 33 is accommodated in the narrowed spaces between the support portions 34. As a result, the elastomer sheet 21 becomes flat as a whole. In this way, it is effective to apply this embodiment to a region where the elastomer sheet 21 is compressible.

[0122] On the other hand, when the bellows portion 33a is stretched, the bellows portion 33a deforms to approach a flat surface. Furthermore, because the bellows portion 33a is supported by the support portion 34a, deformation of the stretched bellows portion 33a is suppressed. Therefore, this embodiment can also be applied to the stretchable region of the elastomer sheet 21a. Therefore, this embodiment can be applied to both the stretchable and compressible portions of the central region 30 and the pair of end regions 31 of the elastomer sheet 21a.

[0123] (Embodiment 3) Next, the elastomer sheet 21b of the electrostatic sensor 20b of the third embodiment will be described with reference to FIGS.

[0124] 11, in the elastomer sheet 21b of this embodiment, the central region 30b and the pair of end regions 31b are disposed continuously in the winding direction Y. The central region 30b and the pair of end regions 31b have a cross-sectional shape in the longitudinal direction X that is a sine wave shape formed by smoothly curved surfaces over the entire length in the longitudinal direction X. The sine wave shape is continuous from the central region 30b to the pair of end regions 31b.

[0125] As shown in FIG. 12 , the sine wave shape is compressed in the longitudinal direction X on the inner peripheral surface 15 of the resin inner layer material 17 constituting the ring portion 12. As a result, the peak-shaped portions and valley-shaped portions of the sine wave shape are deformed so as to approach each other. The sine wave shape then assumes a shape compressed in the longitudinal direction X. Because the amplitude of the sine wave shape is constant before compression, the amplitude of the sine wave shape remains constant even after compression. Furthermore, because the wavelength of the sine wave shape is constant before compression, the wavelength of the sine wave shape remains approximately constant even after compression. This prevents relatively large, uneven wrinkles from forming in the pair of end regions 31b of the elastomer sheet 21 after compression.

[0126] The configuration other than that described above is substantially the same as that of the first embodiment, so the same members are given the same reference numerals and redundant explanations will be omitted.

[0127] (Embodiment 4) Next, an elastomer sheet 21c of a fourth embodiment will be described with reference to Fig. 13. As shown in Fig. 13, in the elastomer sheet 21c of this embodiment, the bellows portion 33c has a shape that is folded multiple times (three times in this embodiment) when viewed from the winding direction Y. This increases the number of places where the plane is folded, making it easier for the bellows portion 33c to compress or expand in the longitudinal direction X. The number of places where the bellows portion 33c is folded may be four or more. The shape of the bellows portion 33c folded multiple times is an example of a wave shape.

[0128] The configuration other than the above is substantially the same as that of embodiment 1, so the same members are denoted by the same reference numerals and redundant explanations will be omitted. However, the shape of bellows portion 33c may be, for example, an N-shape when viewed from the winding direction Y, or any other shape may be adopted.

[0129] (Embodiment 5) Next, an elastomer sheet 21d of a fifth embodiment will be described with reference to Fig. 14. As shown in Fig. 14, a pair of end regions 31d of the elastomer sheet 21d may be configured to be spaced apart from each other when wrapped around the ring portion 12. A gap is formed between the pair of end regions 31d, but this gap is formed uniformly over the entire area of ​​the inner circumferential surface 15 of the ring portion 12, and is not uneven. For this reason, the elastomer sheet 21 d The shape, material, etc. of the skin material 18 that covers the outer surface of the device can be adjusted to prevent the device's appearance from being impaired.

[0130] The configuration other than that described above is substantially the same as that of the first embodiment, so the same members are given the same reference numerals and redundant explanations will be omitted.

[0131] (Embodiment 6) Next, an elastomer sheet 21e according to a sixth embodiment of the electrostatic sensor 20e will be described with reference to Fig. 15. A heater-shield wire 22 is attached to a second surface of the elastomer sheet 21e of this embodiment. The heater-shield wire 22 is adhered or heat-sealed to the elastomer sheet 21e.

[0132] The configuration other than that described above is substantially the same as that of the first embodiment, so the same members are given the same reference numerals and redundant explanations will be omitted.

[0133] According to this embodiment, the heater-cum-shield wire 22 is attached to the elastomer sheet 21e, so that the electrostatic sensor 20e can be made thinner.

[0134] (Embodiment 7) Next, an elastomer sheet 21f of the electrostatic sensor 20f of this embodiment will be described with reference to FIGS. 16 and 17. As shown in FIG. 16, a single sheet-like first electrode layer 25a is disposed on the first surface of the elastomer sheet 21f of this embodiment at the center in the winding direction Y. As shown in FIG. 17, a sheet-like second electrode layer 25b is disposed on the second surface of the elastomer sheet 21f at a position overlapping the first electrode layer when viewed from the thickness direction Z of the elastomer sheet 21. The second electrode layer 25b is formed to have approximately the same size as the first electrode layer 25a. However, the elastomer sheet 21f may also be configured such that an elastomer layer 24f is provided on the first surface and a second surface of the elastomer layer 24f are provided with a first electrode layer 25a and a second electrode layer 25b, each made of a plurality of conductive members, disposed thereon.

[0135] The configuration other than that described above is substantially the same as that of the first embodiment, so the same members are given the same reference numerals and redundant explanations will be omitted.

[0136] The change in capacitance between the first electrode layer 25a arranged on the first surface of the elastomer sheet 21 and the second electrode layer 25b arranged on the second surface of the elastomer sheet 21 can be utilized to function as a sensor.

[0137] The technology disclosed in this specification is not limited to the embodiments described above and illustrated in the drawings, and also includes various aspects such as those described below.

[0138] (1) The electrostatic sensor 20 or elastomer sheet 21 according to this embodiment can be applied not only to the steering wheel 10 but also to other interior components of an automobile.

[0139] (2) The shape of the ring portion of the steering wheel is not limited to a circular ring. For example, the ring portion 42 of the steering wheel 40 may be substantially D-shaped. stomachIn this case, the upper part of the steering wheel 40 forms a part of a ring. The lower part of the steering wheel 40 may be straight, or may be formed into a curved shape that is gently convex upward, as shown in FIG. 18. In this case, the central region 30 of the elastomer sheet 21 wrapped around the lower region of the ring portion 42 on the outer peripheral surface 14 of the resin inner layer material 17 that forms the ring portion 42 is compressed, and a pair of end regions 31 of the elastomer sheet 21 wrapped around the lower region of the ring portion 42 on the inner peripheral surface 15 of the resin inner layer material 17 that forms the ring portion 42 are stretched.

[0140] (3) The shape of the ring portion 52 of the steering wheel 50 may be, for example, a substantially rectangular shape as shown in FIG. 19, or any other shape may be adopted. [Explanation of symbols]

[0141] 10,40,50 steering 12 Ring section 20, 20a, 20b, 20e, 20f Capacitive sensor 21, 21a, 21b, 21c, 21d, 21e, 21f Elastomer sheet 30,30a,30b central area 31,31a, 31b, 31d end area 24,24f Elastomer layer 25a First electrode layer 25b Second electrode layer

Claims

1. An elastomer sheet made of an elastomer that is wound around a target member having a three-dimensional curved surface, a central region located at the center of the winding direction of the elastomer sheet; a pair of end regions located at ends of the elastomer sheet in the winding direction, the central region and the pair of end regions have cross-sectional shapes in a transverse direction intersecting the winding direction of the elastomer sheet that are formed into a wave shape that can be stretched or compressed in the transverse direction, An elastomer sheet configured such that the rate at which the central region stretches or compresses differs from the rate at which the pair of end regions stretch or compress in the cross direction.

2. The elastomeric sheet according to claim 1 , wherein one of the central region and the pair of end regions is configured to be stretchable, and the other is configured to be compressible.

3. The elastomer sheet of claim 2, further comprising a boundary region located at the boundary between the central region and the pair of end regions in the winding direction of the elastomer sheet, the cross-sectional shape of which in the transverse direction before winding the target element is formed in a flat plate shape.

4. The elastomer sheet according to claim 2 , wherein the central region and the pair of end regions are disposed consecutively in the winding direction.

5. The elastomer sheet according to any one of claims 1 to 4, wherein the cross-sectional shape of at least one of the central region and the pair of end regions in the transverse direction is formed in a wave shape over the entire length in the transverse direction.

6. The elastomer sheet according to claim 5 , wherein at least one of the central region and the pair of end regions has a sine wave cross section in the transverse direction before the target member is wrapped around the central region.

7. The elastomer sheet according to claim 6 , wherein the amplitude of the sine wave shape is made smaller as the stretching or compression rate in the cross direction is smaller, and is made larger as the stretching or compression rate is greater.

8. 8. The elastomer sheet according to claim 6, wherein the amplitude of the sine wave shape is continuously reduced from the central region toward the pair of end regions.

9. 8. The elastomer sheet according to claim 6, wherein the amplitude of the sine wave shape is gradually reduced from the central region toward the pair of end regions.

10. At least one of the central region and the pair of end regions is A plurality of bellows portions whose cross-sectional shape in the transverse direction is formed so as to be stretchable or compressible in the transverse direction and which are arranged at predetermined intervals in the transverse direction; a support portion that connects adjacent bellows portions in the crossing direction and is formed to be thicker than the bellows portions in the winding direction and a direction perpendicular to the crossing direction; The elastomer sheet according to any one of claims 1 to 9, comprising:

11. a width dimension of the bellows portion in the cross direction is made smaller as the rate of extension or compression in the cross direction is smaller, and is made larger as the rate of extension or compression in the cross direction is larger, The elastomer sheet according to claim 10 , wherein the width dimension of the support portion in the cross direction is increased as the rate of stretching or compression in the cross direction decreases, and is decreased as the rate of stretching or compression in the cross direction increases.

12. 12. The elastomer sheet according to claim 10, wherein a width dimension of the bellows portion in the transverse direction continuously increases as the bellows portion approaches the pair of end regions, and a width dimension of the support portion in the transverse direction continuously decreases as the bellows portion approaches the pair of end regions.

13. 12. The elastomer sheet according to claim 10, wherein a width dimension of the bellows portion in the transverse direction increases stepwise as it approaches the pair of end regions, and a width dimension of the support portion in the transverse direction decreases stepwise as it approaches the pair of end regions.

14. The target member is a shaft member whose central axis is a convex curve, the central region is located on a surface of the shaft member that is farther from a center of curvature of the convex curve in the circumferential direction thereof, and is formed to be extensible in the intersecting direction; The elastomer sheet according to any one of claims 1 to 13, wherein the pair of end regions are located on a surface of the shaft member that is closer to the center of curvature of the convex curve in the circumferential direction, and are formed to be compressible in the intersecting direction.

15. The target member is an annular shaft member, the central region is located on the outer peripheral surface of the annular shaft member and is formed to be extensible in the intersecting direction, The elastomer sheet according to claim 14 , wherein the pair of end regions are located on an inner peripheral surface of the annular shape of the shaft member and are formed to be compressible in the intersecting direction.

16. The central region has a cross-sectional shape in the transverse direction that is formed in a wave shape over the entire length in the transverse direction, The pair of end regions are A plurality of bellows portions whose cross-sectional shape in the transverse direction is formed so as to be stretchable or compressible in the transverse direction and which are arranged at predetermined intervals in the transverse direction; a support portion that connects adjacent bellows portions in the crossing direction and is formed to be thicker than the bellows portions in the winding direction and a direction perpendicular to the crossing direction; The elastomeric sheet according to claim 14 or 15, comprising:

17. The central region and the pair of end regions are A plurality of bellows portions whose cross-sectional shape in the transverse direction is formed so as to be stretchable or compressible in the transverse direction and which are arranged at predetermined intervals in the transverse direction; a support portion that connects adjacent bellows portions in the crossing direction and is formed to be thicker than the bellows portions in the winding direction and a direction perpendicular to the crossing direction; The elastomeric sheet according to claim 14 or 15, comprising:

18. The central region and the pair of end regions are The elastomer sheet according to claim 14 or 15, wherein the cross-sectional shape in the transverse direction is formed in a wave shape over the entire length in the transverse direction and is continuously disposed in the winding direction.

19. The elastomeric sheet according to any one of claims 1 to 18, comprising an elastomer layer made of an elastomer and an electrode layer disposed on a first surface of the elastomer layer.

20. The elastomeric sheet of claim 19 , wherein a plurality of the electrode layers are arranged in parallel on the first surface of the elastomeric layer.

21. 21. A capacitive sensor, comprising the elastomeric sheet according to claim 19 or claim 20, further comprising a second electrode sheet disposed on a second surface of the elastomeric layer opposite the first surface.

22. An electrostatic sensor, wherein the elastomer sheet described in claim 19 or claim 20 further comprises a heater sheet in which a heater / shield wire that serves as both a heater wire and a shield wire and a base sheet are integrated, the heater sheet being arranged on a second surface opposite the first surface of the elastomer layer.

23. 21. An electrostatic sensor, wherein the elastomer sheet according to claim 19 or 20 further comprises a heater / shield wire that serves as both a heater wire and a shield wire and is attached to a second surface of the elastomer layer opposite the first surface.

24. The elastomer sheet according to any one of claims 1 to 18, a first electrode sheet disposed on a first surface of the elastomer sheet.

25. 25. The capacitive sensor of claim 24, comprising a plurality of the first electrode sheets on the first surface of the elastomeric sheet.

26. 25. The capacitive sensor of claim 24, further comprising a second electrode sheet disposed on a second surface of the elastomeric sheet opposite the first surface.

27. 25. The electrostatic sensor according to claim 24, further comprising a heater sheet in which a heater / shield wire that serves as both a heater wire and a shield wire is integrated with a base sheet, the heater sheet being arranged on a second surface of the elastomer sheet opposite the first surface.

28. 25. The capacitive sensor according to claim 24, further comprising a heater / shield wire that serves as both a heater wire and a shield wire and is attached to a second surface of the elastomer sheet opposite the first surface.

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