Planar unit comprising linear body, steering wheel, and method for producing planar unit

Abstract

Provided is a planar unit which can prevent a user from feeling uncomfortable during operations and the like and can include a plurality of functions. The planar unit (1) includes a substrate (31), a first linear body (11) arranged on one surface of the substrate (31), and a second linear body (21) arranged on the other surface of the substrate (31), the first linear body (11) being one of a heater wire, a sensor wire, or a shielded wire, and the second linear body (21) being one of a heater wire, a sensor wire, or a shielded wire, the base material (31) and the first linear body (11) are coupled to each other by a suture line, a thermally fused portion (29) is formed on the outermost layer of the second linear body (21), and the base material (31) and the second linear body (21) are thermally fused together. The steering wheel comprises the plane unit (1), a wheel core material and a covering material, and the plane unit (1) is installed between the wheel core material and the covering material.

Description

Technical Field

[0001] The present invention relates to a planar unit including a heater unit for heating a rim portion of a steering wheel used, for example, in an automobile or a ship, and a sensor unit for temperature detection or grip detection of the steering wheel. In particular, the present invention relates to a planar unit that prevents a user from feeling discomfort during a steering operation and the like and provides various functions. Background Art

[0002] Conventionally, a heater unit has been proposed to be mounted on a rim portion of a steering wheel to warm a driver's hand during a cold season. The steering wheel is composed of a rim portion, a spoke portion, and a hub portion, and the rim portion is formed of a rim core material produced by covering a metal core with a polyurethane resin or the like and a covering material made of a synthetic resin, a fiber product, leather, or the like. The heater unit is mounted between the rim core material and the covering material and is powered by connecting to a lead wire passing through the spoke portion and the hub portion.

[0003] As a heater unit mounted in a steering wheel, for example, a heater unit in which heater wires are arranged in a predetermined pattern shape on a base material as shown in Patent Documents 1 to 4 is known. In this case, various foamed resin sheets, foamed rubber sheets, rubber sheets, nonwoven fabrics, woven fabrics, etc. are disclosed as the base material. In addition, examples of related art include Patent Documents 5 to 8 and the like.

[0004] Examples of the sensor unit include a sensor unit serving as a capacitance sensor or a temperature sensor. The capacitance sensor is used for a touch panel, a seat occupancy sensor, etc. In particular, a so-called two-electrode type capacitance sensor is widely used in various applications due to its excellent detection sensitivity. The two-electrode type capacitance sensor utilizes the fact that when a human body approaches two insulated electrodes in a proximity state, the capacitance value between the two electrodes changes and detects the change in capacitance. This technology is being considered for, for example, grip detection of a steering wheel. Examples of a sensor unit composed of a linear capacitance sensor are described in Patent Document 9 and the like. Known examples of the temperature sensor include a temperature sensor serving as a temperature sensing device for a heating tool (for example, an electric heating carpet and an electric blanket). These examples adopt a structure in which a sensor wire is wound around a center core wire and the outer periphery of the sensor wire is covered with a sheath, and perform temperature detection by detecting a change in resistance value due to the temperature of the sensor wire. Examples of the use of the sensor wire include arranging the sensor wire near a heat source (for example, a heater wire) to detect the temperature of the heater wire, and arranging the sensor wire in a serpentine shape to detect the temperature as a plane. Examples of a sensor unit composed of a linear temperature sensor are described in Patent Document 10 and the like.

[0005] Citation List

[0006] Patent Document

[0007] [Patent Document 1] Japanese Patent No. 4202071: Kurabe Co., Ltd.

[0008] [Patent Document 2] International Patent Publication No. WO 2014 / 104000: Toyoda Gosei Co., Ltd., Kurabe Co., Ltd.

[0009] [Patent Document 3] Japanese Patent No. 6468701: Kurabe Co., Ltd.

[0010] [Patent Document 4] Japanese Patent No. 6760941: Kurabe Co., Ltd.

[0011] [Patent Document 5] Japanese Patent No. 3991750: Matsushita Electric Industrial Co., Ltd.

[0012] [Patent Document 6] Japanese Patent No. 671727: Kurabe Co., Ltd.

[0013] [Patent Document 7] Japanese Patent No. 671728: Kurabe Co., Ltd.

[0014] [Patent Document 8] Japanese Patent No. 6829577: Kurabe Co., Ltd.

[0015] [Patent Document 9] Japanese Patent No. 6851730: Kurabe Co., Ltd.

[0016] [Patent Document 10] Japanese Patent No. 5562678: Kurabe Co., Ltd. Summary of the Invention

[0017] In the market, it is required that a component has multiple functions. For example, in the above heater unit, it may also be necessary to arrange a circuit of multiple heater wires in one substrate to change the heat generation characteristics, or to arrange heater wires and sensor wires on one substrate so that the substrate has the functions of both a heater and a sensor. On the other hand, when one or more heater wires and one sensor wire are arranged in an overlapping manner, the thickness of this part increases, which may cause discomfort to the user during steering operations and the like. There is also a risk of applying a large force to this overlapping part and causing disconnection. Therefore, due to space limitations, it is difficult to arrange multiple heater wires and one sensor wire only on one surface of the substrate. To solve this problem, it can be envisaged to utilize both surfaces of the substrate so that the pattern of the heater wires on one surface is different from the pattern of the other heater wires on the other surface, or to arrange heater wires on one surface and sensor wires on the other surface.

[0018] The heater units disclosed in Patent Documents 1 to 4 are configured such that heater wires are arranged on a substrate in a predetermined pattern shape and are bonded and fixed. The manufacturing method is as follows. First, a hot press jig provided with a mechanism including a plurality of locking members that can move up and down is used to arrange the heater wires in a predetermined pattern shape while hooking the heater wires on the plurality of locking members. Next, the substrate is arranged on the heater wires. The hot press plate is lowered so that the heater wires and the substrate are subjected to heat and pressure, thereby bonding and fixing the heater wires to the substrate. With such a configuration, the thickness of the position where the heater wires are arranged in the substrate is thin so as to follow the shape of the heater wires, thereby forming a flat shape. With such a configuration, it is difficult to arrange heater wires on both surfaces of the substrate. This is because, since the substrate has already been compressed at the stage of arranging the heater wires on one surface, there is almost no space for substrate compression even if an attempt is made to arrange heater wires, and the heater unit will not be flat.

[0019] The heater units disclosed in Patent Documents 6 to 8 solve the above problems and provide a heater unit by bonding substrates on which heater wires are arranged, thereby arranging heater wires on both surfaces. However, in this case, another process for bonding the substrates is required, and the cost increases because two substrates are needed. In addition, the adhesiveness between the substrates also needs to be considered.

[0020] On the other hand, the heater unit disclosed in Patent Document 5 relates to using a machine such as a sewing machine for sewing to sew heater wires to a substrate using a sewing thread made of a top thread and a bobbin thread. In such a heater unit, the heater wires are fixed to the substrate only by the sewing thread. In order to fix the heater wires to both surfaces of the substrate by this method, after sewing the heater wires to one surface, another heater wire is sewn to the other surface. In such a case, when sewing the heater wires in a subsequent process, the sewing needle may hit the heater wires that have already been fixed, which may cause the heater wires to break. This problem becomes more obvious when the pattern shape is made finer to improve the heater performance.

[0021] As shown in Patent Documents 9 and 10, similar problems also exist in a planar sensor unit in which linear sensor wires are arranged on a substrate.

[0022] The present invention has been made to solve such problems in the related art, and an object of the present invention is to provide a planar unit that can prevent a user from feeling discomfort during a turning operation and the like, and that can include various functions.

[0023] To achieve the above object, a planar unit according to the present invention includes a substrate, a first linear body disposed on one surface of the substrate, and a second linear body disposed on the other surface of the substrate. The first linear body is one of a heater wire, a sensor wire, or a shield wire, and the second linear body is one of a heater wire, a sensor wire, or a shield wire. Wherein the substrate and the first linear body are coupled to each other by a suture, and a heat fusion portion is formed on the outermost layer of the second linear body, and the substrate and the second linear body are heat fused together.

[0024] In addition, a heat fusion portion may be formed on the outermost layer of the first linear body, and the suture may be inserted into the heat fusion portion of the first linear body.

[0025] In addition, the thickness of the positions where the first linear body and the second linear body are disposed in the substrate may be thinner to follow the shapes of the first linear body and the second linear body, and the suture may be inserted into the heat fusion portion of the first linear body and has a substantially flat shape.

[0026] In addition, a heat fusion portion may be formed on the outermost layer of the first linear body. The planar unit may include a suture trace generated by melting the suture that couples the first linear body and the substrate to each other, and the heat fusion portion of the first linear body and the suture trace may be flattened.

[0027] In addition, the thickness of the positions where the first linear body and the second linear body are disposed in the substrate may be thinner to follow the shapes of the first linear body and the second linear body, and the heat fusion portion of the first linear body and the suture trace may be flattened and has a substantially flat shape.

[0028] Furthermore, a steering wheel according to the present invention includes the above planar unit, a wheel core material, and a covering material, wherein the planar unit is mounted between the wheel core material and the covering material.

[0029] In a method of manufacturing a planar unit according to the present invention, the first linear body is one of a heater wire, a sensor wire, or a shield wire, and the second linear body is one of a heater wire, a sensor wire, or a shield wire, and the method includes: fixing the first linear body to one surface of a substrate by a suture; disposing the second linear body including the outermost layer on the other surface of the substrate in a predetermined pattern shape, a heat fusion portion being formed on the outermost layer of the second linear body; and applying heat and pressure to the substrate, the first linear body, and the second linear body such that the thickness of the positions where the first linear body and the second linear body are disposed in the substrate follows the shapes of the first linear body and the second linear body and using the heat fusion portion to fix the substrate and the second linear body to each other.

[0030] In addition, the first linear body may include an outermost layer, a heat-sealing portion is formed on the outermost layer of the first linear body, and the above method may include: when heat and pressure are applied to the first linear body and the second linear body, inserting the suture into the heat-sealing portion of the first linear body, so that the suture assumes a substantially flat shape; and using the heat-sealing portion to fix the base material and the second linear body to each other.

[0031] In addition, the first linear body may include an outermost layer, a heat-sealing portion is formed on the outermost layer of the first linear body, and the above method may include: when heat and pressure are applied to the first linear body and the second linear body, melting the suture and the heat-sealing portion; flattening the suture trace generated by melting the suture and the heat-sealing portion, so that the suture trace and the heat-sealing portion assume a substantially flat shape; and using the heat-sealing portion to fix the base material and the first linear body to each other.

[0032] According to the present invention, by combining sewing with the application of heat and pressure when arranging the linear body in the base material, a flat unit that remains flat even after the linear body is arranged on two corresponding surfaces of the base material can be obtained. Therefore, a flat unit can be provided that can prevent a user from feeling discomfort during turning operations and the like, and can include various functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a plan view showing the configuration of one surface of the flat unit according to the present invention;

[0034] Figure 2 is a plan view showing the configuration of another surface of the flat unit according to the present invention;

[0035] Figure 3 is a cross-sectional view schematically showing an enlarged view of a main part of the flat unit according to the first embodiment of the present invention;

[0036] Figure 4 is a cross-sectional view schematically and enlargedly showing a main part of an intermediate stage of manufacturing the flat unit according to an embodiment of the present invention;

[0037] Figure 5 is a schematic view showing an embodiment of the present invention, which is a schematic view showing the configuration of a hot press heater manufacturing apparatus;

[0038] Figure 6 is a partial perspective view showing a case where the linear bodies are arranged in a predetermined pattern shape in the heater unit according to the present invention;

[0039] Figure 7 is a cross-sectional photograph of a main part of the flat unit according to the first embodiment of the present invention;

[0040] Figure 8 is a cross-sectional photograph of a main part of a planar unit according to a second embodiment of the present invention;

[0041] Figure 9 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0042] Figure 10 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0043] Figure 11 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0044] Figure 12 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0045] Figure 13 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0046] Figure 14 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0047] Figure 15 is a partially cut-away side view showing an example of a heater wire used in the present invention;

[0048] Figure 16 is a partially cut-away side view showing an example of a sensor wire used in the present invention;

[0049] Figure 17 is a partially cut-away side view showing an example of a sensor wire used in the present invention;

[0050] Figure 18 is a partially cut-away perspective view showing a state where a planar unit according to the present invention is embedded in a vehicle steering wheel; and

[0051] Figure 19 is a partially cut-away perspective view showing a state where a planar unit according to the present invention is embedded in a vehicle seat. Detailed Description of the Invention

[0052] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments represent examples where a heater wire is used as the first linear body, a sensor wire is used as the second linear body, and a planar unit according to the present invention is applied to a vehicle steering heater.

[0053] First, reference will be made to Figures 1 to 3Describe the first embodiment. Now, the configuration of the first linear body (i.e., the heater wire 11) according to the first embodiment will be described. The heater wire 11 according to the first embodiment is configured as shown in Figure 9 and Figure 10 . First, the core wire 13 is formed of an aromatic polyamide fiber bundle with an outer diameter of approximately 0.2 mm. Five parallel conductor strands 15a made of a copper alloy wire with a strand diameter of 0.08 mm and containing hard tin are spirally wound around the outer periphery of the core wire 13 at an approximate pitch of 1.0 mm. As shown in Figure 9 and Figure 10 , an insulating film 15b is formed around the conductor strands 15a. The insulating film 15b is formed of an inner layer 15c made of a polyurethane resin and an outer layer 15d made of a polyamideimide resin. The inner layer 15c of the insulating film 15b is formed into a layer with a thickness of 4 μm by applying a polyurethane varnish around the conductor strands 15a and drying the polyurethane varnish. Next, the outer layer 15d is formed into a layer with a thickness of 4 μm by applying a polyamideimide varnish on the outer periphery of the inner layer 15c and drying the polyamideimide varnish. The outer periphery of the core wire 13 around which the conductor strands 15a are wound is coated with an insulating film. The insulating film is formed by extrusion coating such that a polyethylene resin mixed with a flame retardant exhibits a thickness of 0.2 mm. In this embodiment, the polyethylene resin of the insulating film functions as the heat fusion joint 19. The final outer diameter of the heater wire 11 configured as described above is 0.8 mm. The core wire 13 is effective in enhancing flexibility and tensile strength. It is also possible to arrange or strangle a plurality of conductor strands in parallel without using the core wire 13.

[0054] Next, the configuration of the second linear body (i.e., the sensor wire 21) according to the first embodiment will be described. The heater wire 21 according to the first embodiment is configured as shown in Figure 16 and Figure 17 . First, the core wire 23 is formed of an aromatic polyamide fiber bundle with an outer diameter of approximately 0.2 mm. Two parallel conductor strands 25a made of a copper alloy wire with a strand diameter of 0.08 mm and containing hard tin are spirally wound around the outer periphery of the core wire 23 at an approximate pitch of 1.0 mm. As shown in Figure 16 and Figure 17As shown, an insulating film 25b is formed around the conductor strand 25a. The insulating film 25b is formed of an inner layer 25c made of a polyurethane resin and an outer layer 25d made of a polyamideimide resin. The inner layer 25c of the insulating film 25b is formed into a layer with a thickness of 4 μm by applying a polyurethane varnish around the conductor strand 25a and drying the polyurethane varnish. Next, the outer layer 25d is formed into a layer with a thickness of 4 μm by applying a polyamideimide varnish to the outer periphery of the inner layer 25c and drying the polyamideimide varnish. The outer periphery of the core wire 23 surrounded by the wound conductor strand 25a is coated with an insulating film. The insulating film is formed by extrusion coating so that the polyethylene resin mixed with a flame retardant has a thickness of 0.2 mm. In this embodiment, the polyethylene resin of the insulating film functions as the heat fusion joint 29. The final outer diameter of the sensor wire 21 configured as described above is 0.8 mm. The sensor wire 21 detects the capacitance value between the two conductor strands 25a.

[0055] Next, the configuration of the base material 31 in which the heater wire 11 and the sensor wire 21 configured as described above are arranged will be described. The base material 31 according to the first embodiment is made of a foamed polyurethane resin, and the apparent density of the foamed polyurethane resin is 40 kg / m 3 (in compliance with JIS K7222), the hardness is 220 N (in compliance with JIS K 6400), and the thickness is 8 mm. The base material 31 can be formed into a desired shape by a known method (such as die cutting).

[0056] Next, the configuration in which the above-mentioned heater wire 11 is arranged on one surface of the base material 31 in a predetermined pattern shape will be described. The base material 31 is arranged on a movable table, and the heater wire 11 is arranged on a heater wire supply machine installed together with a sewing machine for sewing. The heater wire 11 is supplied to the front of the needle bar unit of the sewing machine for sewing, and the movable table moves synchronously with the heater wire in a predetermined mode. At the same time, the heater wire 11 is sewn to the base material 31 by the sewing machine for sewing. In this way, the heater wire 11 is arranged on the base material 31 in a serpentine shape. Figure 4 is a cross-sectional view showing a main part of the planar unit 1 in an enlarged manner in a state where the heater wire 11 has been sewn to the surface of the base material 31. The sewing thread is composed of the upper thread 33 and the bobbin thread 35. The upper thread 33 wraps around the entire circumference of the heater wire 11 approximately and winds together with the bobbin thread 35 and is sewn to the base material 31 on the rear side. The upper thread 33 is a polyester filament yarn of 165 dtex, and the bobbin thread 35 is a polyester filament yarn of 165 dtex. The sewing pitch is set to 2 mm in the linear part of the serpentine shape and 1 mm in the curved part of the serpentine shape.

[0057] Next, the configuration in which the above-mentioned heater wire 21 is arranged on the other surface of the base material 31 in a predetermined pattern shape will be described.Figure 5 This is a schematic diagram showing the configuration of a hot press heater manufacturing apparatus 43 for joining and fixing a sensor wire 21 to a base material 31. First, the hot press jig 45 will be described. A plurality of locking mechanisms 47 are arranged on the upper surface of the hot press jig 45. As Figure 6 shown, each of the above-mentioned locking mechanisms 47 includes a pin 49, and the pin 49 is inserted into a hole drilled in the hot press jig 45 from the bottom of the hole toward the top of the hole. A locking member 53 is attached to the upper surface of the pin 49 such that the locking member 53 can move in the axial direction of the pin 49, and the locking member 53 is constantly biased upward by a helical spring 55. Additionally, as Figure 6 shown by the dashed line in, when the sensor wire 21 is joined to the locking members 53 on the upper surfaces of a plurality of corresponding locking mechanisms 47, the sensor wire 21 is arranged in a predetermined pattern shape corresponding to the positions of the locking members 53.

[0058] Referring again to Figure 5 , a hot press plate 57 is arranged above the above-mentioned plurality of locking mechanisms 47 such that the hot press plate 57 can move up and down. First, the sensor wire 21 is arranged to draw a predetermined pattern shape while being hooked by the locking members 53 of the plurality of locking mechanisms 47. Next, the base material 31 is placed on the sensor wire 21 such that the surface of the base material 31 on which the heater wire 11 is not arranged faces the sensor wire 21. In this state, the hot press plate 57 descends and presses the base material 31 against the sensor wire 21. At this time, for example, the hot press plate 57 applies heat and pressure of 230 °C / 5 seconds to the base material 31 and the sensor wire 21. Then, the heat fusion joint 19 of the heater wire 11 and the heat fusion fibers of the base material 31 are fused to each other by heat and pressure, and the heat fusion joint 29 of the sensor wire 21 and the heat fusion fibers of the base material 31 are also fused to each other by heat and pressure. Thus, the heater wire 11, the sensor wire 21, and the base material 31 are joined and fixed to each other. In the process of doing so, the hot press jig 45 can also be heated.

[0059] By performing the above operations, a planar unit 1 similar to the Figures 1 to 3 shown planar unit can be obtained. Note that Figure 2 is a plan view showing the surface opposite to the Figure 1 shown surface, Figure 3 is a view showing Figure 1Cross-sectional view of an enlarged view of the main part. Since the base material 31 is to be compressed by the hot press plate 57, the positions where the heater wires 11 and the sensor wires 21 are arranged will be subjected to higher pressure. Therefore, the positions in the base material 31 where the heater wires 11 and the sensor wires 21 are arranged are given a higher density than other positions and become thinner, while presenting a shape that follows the shapes of the heater wires 11 and the sensor wires 21. Therefore, the surfaces of the planar unit 1 where the heater wires 11 and the sensor wires 21 are arranged each present a flat shape without irregularities, even in the positions where the heater wires 11 and the sensor wires 21 are arranged. In addition, since the base material 31 in the planar unit 1 obtained in this way is compressed and has a high density, the mechanical strength can be improved.

[0060] In addition, due to the heat and pressure applied by the hot press plate 57, the surface thread 33 is inserted into the heat fusion joint 19 of the heater wire 11. Therefore, the protrusion caused by the sewing thread (surface thread 33) disappears, and the surface of the planar unit 1 where the heater wire 11 is arranged presents a flat shape. Figure 7 A cross-sectional photograph of the planar unit 1 according to the first embodiment is shown. As Figure 7 shown, it can be confirmed that the surface thread 33 is inserted into the heat fusion joint 19 of the heater wire 11.

[0061] Furthermore, since the base material 31 and the heater wire 11 are fixed by heat fusion bonding after the heater wire 11 is fastened and fixed to the base material 31 by the sewing threads (surface thread 33 and bottom thread 35), the flatness of the planar unit 1 can be further improved.

[0062] The thickness of the planar unit 1 obtained according to the first embodiment is 2.0 mm, the thickness of the base material 31 at the position where the heater wire 11 is arranged is 1.4 mm, the thickness of the base material 31 at the position where the sensor wire 21 is arranged is 1.4 mm, the thickness of the base material 31 at the position where the heater wire 11 and the sensor wire 21 are arranged is 0.8 mm, and the thickness of the base material 31 at the position where the heater wire 11 and the sensor wire 21 are not arranged is 2.0 mm. In addition, the apparent density of the base material 31 in the position where the heater wire 11 or the sensor wire 21 is not arranged is 160 kg / m 3 (conforming to JIS K7222), and the hardness is ASKER C 15 (conforming to JIS K 7312).

[0063] The heat fusion parts 19 in the outer periphery of the heater wire 11 and the heat fusion parts 29 in the outer periphery of the sensor wire 21 are deformed and flow due to the applied heat and pressure, and a part of these heat fusion parts penetrates into the voids (pores) of the base material 31. In addition, there are no irregularities in the positions where the heater wire 11 and the sensor wire 21 are arranged, and it is substantially flat even when compared with the outer peripheral thickness. In this case, a thickness change within the range of about ±10% can be described as substantially flat, and it represents a substantially approximately constant thickness. In addition, a thickness change within or near the range where irregularities are not felt visually and tactilely by the user can be described as substantially flat.

[0064] In the planar unit 1 obtained as described above, both ends of the heater wire 11 are led out and connected to the lead wire 37, and the lead wire 37 connects the heater wire 11, the temperature control device 39, and a connector (not shown). The temperature control device 39 is arranged on the heater wire 11, and temperature control of the planar unit is performed due to the heat generated by the heater wire 11. In addition, both ends of the sensor wire 21 are also led out and connected to another lead wire 37, and a connector (not shown) is connected to this lead wire. In addition, connection can be made to the electrical system (not shown) of the vehicle via the above-mentioned connector.

[0065] The planar unit 1 configured as described above is installed in the steering wheel 71 in the state as Figure 18 shown. The steering wheel 71 is composed of a wheel portion 72, a spoke portion 73, and a hub portion 74, and the planar unit 1 is installed between the wheel core material 77 and the covering material 78 of the wheel portion 72.

[0066] An adhesive layer (not shown) for bonding the planar unit 1 and the covering material 78 of the steering wheel to each other, or for bonding the planar unit 1 and the wheel core material 77 of the steering wheel to each other, is formed in the base material 31. This adhesive layer is preferably formed by previously forming an adhesive layer composed only of an adhesive on a release sheet and transferring the adhesive layer to the surface of the base material 31 from the release sheet. Thereby, penetration of the adhesive into the base material 31 is prevented, and the adhesive layer is formed only on the surface of the base material 31.

[0067] When installing the planar unit 1 into the steering wheel, any one of the first manufacturing process to the fourth manufacturing process described below is used.

[0068] (First manufacturing process)

[0069] In the first manufacturing process, the planar unit 1 and the covering material 78 are bonded to each other, and in the process, the surface on the side where the heater wire 11 is arranged is bonded to the covering material 78. Subsequently, the wheel core material 77 is covered with the covering material 78 to which the planar unit 1 has been bonded.

[0070] (Second manufacturing process)

[0071] In the second manufacturing process, the planar unit 1 and the covering material 78 are joined to each other, and in the process, the surface on the side where the heater wire 11 is not arranged is joined to the covering material 78. Subsequently, the wheel core material 77 is covered with the covering material 78 to which the planar unit 1 has been joined.

[0072] (Third manufacturing process)

[0073] In the third manufacturing process, the planar unit 1 and the wheel core material 77 are joined to each other, and in the process, the surface on the side where the heater wire 11 is arranged is joined to the wheel core material 77. Subsequently, the wheel core material 77 to which the planar unit 1 has been joined is covered with the covering material 78.

[0074] (Fourth manufacturing process)

[0075] In the fourth manufacturing process, the planar unit 1 and the wheel core material 77 are joined to each other, and in the process, the surface on the side where the heater wire 11 is not arranged is joined to the wheel core material 77. Subsequently, the wheel core material 77 to which the planar unit 1 has been joined is covered with the covering material 78.

[0076] (Second embodiment)

[0077] The planar unit 1 is obtained by using polylactic acid fiber with an outer diameter of 0.165 mm as the surface thread 33 and 110 dtex low-melting-point polyethylene yarn as the bottom thread 35 as the suture thread in the above first embodiment, but under other conditions similar to those in the first embodiment.

[0078] In the second embodiment, the surface thread and the bottom thread are melted by the heat and pressure applied by the thermal compression heater manufacturing device 43, and suture marks are formed near the heater wire of the planar unit. Since the suture marks are also flattened by the applied heat and pressure, the surface on which the heater wire 11 is arranged in the planar unit 1 has a flat shape. Figure 8 A cross-sectional photograph of the planar unit 1 according to the second embodiment is shown. As Figure 8 shown, it can be confirmed that the heat fusion part of the heater wire and the suture marks have been flattened.

[0079] By using the methods described in the first to fourth manufacturing processes, each of the planar units 1 according to the first and second embodiments obtained as described above is installed in the steering wheel 71 (as Figure 18The steering wheel 71 was put into actual use in this state, and it was checked whether there was any discomfort with the steering wheel. The inspection was performed by having 10 users hold the steering wheel and perform 10 left steering operations and 10 right steering operations, asking the users whether they felt irregularity, and studying the number of subjects who experienced discomfort.

[0080] With regard to the planar units according to the first to third embodiments, no users said that they experienced a sense of discomfort, regardless of the manufacturing process for mounting the planar units in the steering wheel.

[0081] In particular, with respect to the planar unit 1 according to the above-described first and second embodiments, not only irregularities due to the linear bodies (e.g., the heater wire 11 and the sensor wire 21) but also irregularities due to the sewing lines (e.g., the surface line 33 and the bottom line 35) do not occur, and the planar unit 1 has a flat shape. Therefore, even if the planar unit 1 is assembled to the steering wheel using various methods, irregularities due to the linear bodies do not occur, and the user can be prevented from feeling a sense of discomfort during the steering operation. In addition, since the base material 31 is fixed to the linear bodies by heat fusion after the linear bodies (e.g., the heater wire 11 and the sensor wire 21) are fastened and fixed to the base material 31 by the sewing lines, the flatness of the planar unit 1 can be further improved.

[0082] Note that the present invention is not limited to the embodiments described above. The first linear body may be used as the sensor line 21 and the second linear body may be used as the heater line, or both the first linear body and the second linear body may be used as the heater line 11, or both the first linear body and the second linear body may be used as the sensor line 21. The planar unit 1 is made into a heater unit using the heater line 11, and the planar unit 1 is made into a sensor unit using the sensor line 21. The sensor line 21 may be used as a sensor other than a capacitive sensor, such as a temperature sensor. As a temperature sensor, an abnormal temperature sensing unit may be manufactured using a solder wire as a linear body. In terms of sensing radio waves, an antenna unit may be manufactured using an antenna wire as a linear body. In addition, a linear body may be used that includes both a conductor that provides a heater function and a conductor that provides a sensor function.

[0083] In addition, it is contemplated that a shielded wire may be used as one of the first linear body or the second linear body. The shielded wire is used to prevent electromagnetic waves from the heater wire 11 from affecting the outside, or to prevent electromagnetic waves from affecting the sensor wire 21 from affecting the outside. Usually, one or both ends of the shielded wire are grounded.

[0084] Various conventionally known rope-shaped heaters may be used as the heater wire 11 , and for example, the following configuration may be employed.

[0085] 1. As described in the above embodiments and Figure 9 as shown, the heater wire 11 is formed by first twisting or arranging in parallel a plurality of conductor strands 15a coated with the insulating film 15b, winding the conductor strands 15a around the core wire 13, and then coating the outer periphery of the conductor strands 15a with the heat fusion part 19.

[0086] 2. As Figure 11 shown, the heater wire 11 is formed by twisting a plurality of conductor strands 15a coated with the insulating film 15b.

[0087] 3. As Figure 12 shown, the heater wire 11 is formed by arranging in parallel a plurality of conductor strands 15a coated with the insulating film 15b.

[0088] 4. As Figure 13 shown, the heater wire 11 is formed by alternately arranging the conductor strands 15a coated with the insulating film 15b and the conductor strands 15a not coated with the insulating film 15b.

[0089] 5. As Figure 14 shown, the heater wire 11 is formed by arranging in parallel the conductor strands 15a coated with the insulating film 15b and arranging them in such a state that: compared with the conductor strands 15a Figure 13 shown, the number of the conductor strands 15a coated with the insulating film 15b is increased.

[0090] 6. As Figure 15 shown, the heater wire 11 in which the insulating film 17 is separated from the heat fusion part 19 is formed.

[0091] It is conceivable that the heater wire 11 has various configurations other than the above configurations. In addition, the heater wire 11 can also be formed by twisting the core wire 13 and the conductor strands 15a. Unless otherwise specified, any component applicable to the heater wire 11 can also be applied to the sensor wire 21 and the shield wire.

[0092] Examples of the core wire 13 include fibers configured such that their core material is a monofilament, multifilament, spun yarn, their fiber material, or an organic polymer material constituting an inorganic fiber (e.g., glass fiber) or an organic fiber (e.g., polyethylene terephthalate and other polyester fibers, aliphatic polyamide fibers, aromatic polyamide fibers, or wholly aromatic polyester fibers), and the periphery of the core material is coated with a thermoplastic organic polymer material. In the case of using the core wire 13 having heat shrinkability and heat fusibility, when the conductor strand 15a is disconnected and abnormal heating occurs, the core wire 13 melts, disconnects, and shrinks. When the core wire 13 shrinks, since the conductor strand 15a wound around the core wire 13 follows the movement of the core wire 13, the ends of the disconnected conductor strand 15a are separated from each other. Therefore, the situation where the corresponding ends of the disconnected conductor strand 15a contact or separate from each other is not repeated. In addition, the situation where the corresponding ends of the disconnected conductor strand 15a contact each other with a small contact area (e.g., point contact) does not occur. As a result, abnormal heating can be prevented. Further, when the conductor strand 15a is insulated by the insulating film 15b, the core wire 13 does not necessarily need to be formed of an insulating material. For example, a stainless steel wire or a titanium alloy wire can be used as the core wire 13. However, since there is a possibility that the conductor strand 15a can be disconnected, it is advantageous for the core wire 13 to be formed of an insulating material.

[0093] As the conductor strand 15a, conventionally known conductor strands such as copper wire, copper alloy wire, nickel wire, iron wire, aluminum wire, nichrome wire, and ferrochrome wire can be used. Examples of the copper alloy wire include tin-copper alloy wire, copper-nickel alloy wire, and silver-containing copper alloy wire, and the silver-containing copper alloy wire contains a copper solid solution and fibrous copper-silver eutectic. Among these wires, from the viewpoint of the balance between cost and characteristics, preferably, copper wire or copper alloy wire is used. Although the copper wire or copper alloy wire includes soft copper wire or copper alloy wire and hard copper wire or copper alloy wire, from the viewpoint of bending resistance, the hard wire is particularly preferred compared to the soft wire. Note that the hard copper wire or hard copper alloy wire refers to a wire in which each metal particle is stretched in the processing direction by a cold working process (drawing process) and becomes a fibrous structure. When this hard copper wire or hard copper alloy wire is heated to the recrystallization temperature or higher than the recrystallization temperature, the processing strain generated inside the metal particle is eliminated, and crystal nuclei, which are the nuclei of new metal particles, start to appear. The following recrystallization occurs: in this recrystallization, the crystal nuclei grow and successively replace the old crystal nuclei; and a state in which the grains further grow is formed. The soft copper wire or soft copper alloy wire is a wire in a state in which such grains have grown. Although the soft copper wire or soft copper alloy wire has a higher elongation rate and resistance value than the hard copper wire or hard copper alloy wire, it has a lower tensile strength, and the bending resistance of the soft copper wire or soft copper alloy wire is lower than that of the hard copper wire or hard copper alloy wire. In this way, since the hard copper wire or hard copper alloy wire becomes a soft copper wire or soft copper alloy wire with low bending resistance due to heat treatment, it is preferable to perform processing with as little heat history as possible. Note that the hard copper wire is also defined in JIS-C 3101 (1994) and the soft copper wire is also defined in JIS-C 3102 (1984), and the following copper wires are regarded as soft copper wires: when the outer diameter ranges from 0.10 mm to 0.26 mm, the elongation rate is 15% or more; when the outer diameter ranges from 0.29 mm to 0.70 mm, the elongation rate is 20% or more; when the outer diameter ranges from 0.80 mm to 1.8 mm, the elongation rate is 25% or more; and when the outer diameter ranges from 2.0 mm to 7.0 mm, the elongation rate is 30% or more. In addition, the copper wire includes tinned copper wire. The tinned hard copper wire is defined in JIS-C 3151 (1994) and the tinned soft copper conductor is defined in JIS-C 3152 (1984). Furthermore, the conductor strand 15a having various cross-sectional shapes can be used, and in addition to the conductor strand with a generally used circular cross-section, so-called rectangular wire can also be used.

[0094] When the sensor wire for temperature detection is used as a linear body, the conductor strand 25a is preferably made of a material whose resistance value changes significantly with temperature. Examples include various metal wires such as copper wire, copper alloy wire, nickel wire, iron wire, aluminum wire, nichrome wire, constantan wire, and ferrochrome alloy wire; carbon fiber wire and conductive resin wire. Among these wires, wires with a positive temperature coefficient are preferred. Nickel wire and platinum wire with a particularly large coefficient can be preferably used. When the wire has a positive temperature coefficient, since the resistance value increases with the increase in temperature, a control method of determining temperature abnormality and stopping power supply when the resistance value increases will be adopted. Therefore, in the case where the conductor strand 25a is disconnected, since the resistance value reaches an infinite value, the power supply is stopped in the same manner as when an abnormal temperature occurs. This is an extremely reliable method when used as a safety device.

[0095] When the conductor strand 15a is wound around the core wire 13, among the materials of the above-mentioned conductor strand 15a, a material with a small amount of springback when winding the conductor strand 15a is advantageous. For example, for a silver-containing copper alloy wire containing a copper solid solution and fibrous copper-silver eutectic, although high tensile strength characteristics and excellent tensile strength and bending strength are achieved, the possibility of springback during winding is very high. Therefore, such a material is not preferred because when the conductor strand 15a is wound around the core wire 13, floating of the conductor strand 15a or breakage of the conductor strand 15a may occur due to excessive winding tension, and habitual twisting may occur after processing. In particular, when the mode in which the conductor strand 15a is coated with the insulating film 15b is adopted, the restoring force generated by the insulating film 15b is additionally applied. Therefore, it is important to select a material with a low recovery rate as the conductor strand 15a to compensate for the restoring force generated by the insulating film 15b.

[0096] The insulating film 15b covering the conductor strand 15a can be formed of two layers, an inner layer 15c and an outer layer 15d, as in the above embodiment, or can be formed of three or more layers, or can be formed of a single layer. When multiple layers are adopted, the pyrolysis temperature of the material constituting the inner layer is preferably lower than the lower of the melting point and the pyrolysis temperature of the material constituting the outer layer. In this case, the inner layer is the layer formed on the conductor strand 15a. In addition, since the outer layer only needs to be located outside the inner layer, another outer layer can be further formed outside the outer layer, or another intermediate layer can be formed between the inner layer and the outer layer.

[0097] Examples of the material of the insulating film 15b include various materials such as polyurethane resin, polyamide resin, polyimide resin, polyamideimide resin, polyesterimide resin, nylon resin, polyester nylon resin, polyethylene resin, polystyrene resin, polypropylene resin, polyester resin, polybenzimidazole resin, vinyl chloride resin, fluororesin, and silicone resin. A plurality of these materials may be used in combination, or these materials may be mixed with various known additives such as flame retardants or antioxidants. When combining the materials of these resins, the pyrolysis temperature of the material constituting the inner layer is set to be lower than the lower of the melting point and the pyrolysis temperature of the material constituting the outer layer. As the material of the inner layer, polyurethane resin, vinyl chloride resin, polyacetal resin, polystyrene resin, polypropylene resin, polymethyl methacrylate, polyester resins such as polyethylene terephthalate, and polyvinyl alcohol can be selected. In particular, preferably, the material of the inner layer is a thermosetting resin, and the material constituting the outer layer is a thermosetting resin. In this case, the thermosetting resin includes a crosslinkable material. From the viewpoint of the heat generation characteristics of the heater wire and the workability of the terminal (such as welding), preferably, the material of the inner layer is polyurethane resin or polyester resin, and the material of the outer layer is any one of polyimide resin, polyamideimide resin, and silicone resin. In particular, preferably, the material of the inner layer is polyurethane resin, and the material of the outer layer is polyamideimide resin. The polyurethane resin can be modified or mixed in various ways, such as in the case of imide-containing polyurethane and the like.

[0098] In addition, the thickness of the insulating film 15b is preferably 3% to 30% of the diameter of the conductor strand 15a. When it is less than 3%, it may not be possible to obtain sufficient withstand voltage characteristics, and coating the conductor strand 15a alone becomes meaningless. If it exceeds 30%, it becomes difficult to remove the insulating film 15b when crimping the connection terminal, and the heater wire ultimately becomes unnecessarily thick.

[0099] When arranging the above-mentioned conductor strands 15a in parallel or twisting them and winding the conductor strands 15a around the core wire 13, parallel arrangement is more preferable than twisting. This is because parallel arrangement makes the diameter of the heater wire smaller and also enables a smooth surface. In addition to parallel arrangement or twisting, it is conceivable to braid the conductor strands 15a around the core wire 13.

[0100] As the heater wire 11 according to the present invention, it is also conceivable to have a heater wire in which an insulating film 17 is formed on the outer periphery of the conductor strand 15a (for example, refer to Figure 15)。Due to the insulating film 17, when the conductor strand 15a is disconnected, the power supply to other components is insulated, and even when a spark occurs, the heat generation at high temperature is thermally insulated. When forming the insulating film 17, the insulating film 17 can be formed by extrusion molding or the like, or the insulating film 17 preformed into a tubular shape can be covered, and the forming method is not particularly limited. When forming the insulating film 17 by extrusion molding, since the position of the conductor strand 15a becomes fixed and the friction and bending of the conductor strand 15a due to displacement can be prevented, the bending resistance is increased and thus it is preferred. The material constituting the insulating film 17 can also be appropriately designed according to the usage mode or usage environment of the heater wire, and examples of the material constituting the insulating film 17 include various materials such as polyolefin-based resins, polyester-based resins, polyurethane-based resins, aromatic polyamide-based resins, aliphatic polyamide-based resins, vinyl chloride resins, modified Noryl resins (polyphenylene ether resins), nylon resins, polystyrene resins, fluororesins, synthetic rubbers, fluororubbers, vinyl thermoplastic elastomers, urethane-based thermoplastic elastomers, styrene-based thermoplastic elastomers, and polyester-based thermoplastic elastomers. In particular, a flame-retardant polymer composition is preferably used. The flame-retardant polymer composition described herein refers to a polymer composition having an oxygen index of 21 or higher according to the measurement of combustion behavior specified in JIS-K7201 (1999). A polymer composition having an oxygen index of 26 or higher is particularly preferred. In order to obtain such flame retardancy, the material constituting the above insulating film 17 can be appropriately mixed with a flame retardant or the like. Examples of the flame retardant include: metal hydroxides (such as magnesium hydroxide, aluminum hydroxide), antimony oxide, melamine compounds, phosphorus-based compounds, chlorine-based flame retardants, and bromine-based flame retardants. These flame retardants can be appropriately surface-treated using known methods.

[0101] By forming a heat fusion joint portion 19 on the outer periphery of the heater wire 11, the heater wire 11 can be heat-fused to the base material 31 by applying heat and pressure. When forming the insulating film 17, the heat fusion joint portion 19 is formed on the outer periphery of the insulating film 17. As the material constituting the heat fusion joint portion 19, a material similar to the material constituting the above-mentioned insulating film 17 can be used. Among these materials, an olefin-based resin having excellent adhesiveness to the base material is preferred. Examples of the olefin-based resin include: high-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, polypropylene, polybutene, ethylene-α-olefin copolymer, and ethylene-unsaturated ester copolymer. Among these examples, ethylene-unsaturated ester copolymer is particularly preferred. Since the ethylene-unsaturated ester copolymer has a molecular structure containing oxygen in the molecule, compared with a resin whose molecular structure is composed only of carbon and hydrogen (such as polyethylene), the heat of combustion is reduced, thereby suppressing combustion. In addition, due to its high inherent adhesiveness, it has good adhesiveness to the base material, and since the decrease in adhesiveness when mixing inorganic powder and the like is minimal, various flame retardants can be appropriately mixed. Examples of the ethylene-unsaturated ester copolymer include ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, and ethylene-butyl (meth)acrylate copolymer, which can be used alone, or a mixture of two or more of these copolymers can be used. In this case, "(meth)acrylate" represents both acrylic acid and methacrylic acid. Although the material can be arbitrarily selected from these materials, preferably, the selected material melts at a temperature equal to or lower than the starting temperature, or melts at a temperature equal to or lower than the melting point of the material constituting the above-mentioned insulating film 15b. In addition, an example of a material having excellent adhesiveness to the base material 31 is a polyester-based thermoplastic elastomer. Although the polyester-based thermoplastic elastomer includes polyester-polyester type and polyester-polyether type, the polyester-polyether type has higher adhesiveness and is therefore preferred. Note that when heat-fusing the heater wire 11 and the base material 31 to each other, the adhesive strength between the heater wire 11 and the base material 31 is particularly important. When the adhesive strength is insufficient, due to repeated use, the heater wire 11 detaches from the base material 31, thereby applying an unexpected bend to the heater wire 11, and thus there is a possibility that the conductor strand 15a breaks. When the conductor strand 15a breaks, not only does the conductor strand 15a no longer function as a heater, but there is also a risk of generating sparks due to vibration.

[0102] When forming the insulating film 17, the melting point of the insulating film 17 needs to be higher than that of the heat fusion bonding portion 19. Therefore, the shape deformation of the insulating film 17 is almost completely avoided, and sufficient insulating performance can be maintained even when the heat fusion bonding portion 19 is fused by applying heat and pressure or the like. The melting point of the insulating film 17 is preferably in the range of 215°C to 250°C, and the melting point of the heat fusion bonding portion 19 is preferably in the range of 100°C to 185°C. In addition, when forming the insulating film 15b on the conductor strand 15a, the melting point of the insulating film 17 is preferably lower than that of the insulating film 15b.

[0103] In addition, the material constituting the insulating film 17 and the material constituting the heat fusion bonding portion 19 are preferably the same type of polymer material. In such a case, the same type of polymer material is a polymer material sharing a common main chain structure respectively, a polymer material sharing a common functional group respectively, a polymer material having only different molecular weights from each other, a copolymer sharing a common monomer unit respectively, a mixture mixed with a common polymer material, etc. By adopting such materials, since the insulating film 17 and the heat fusion bonding portion 19 are sufficiently joined to each other, the heater wire can be prevented from detaching from the substrate.

[0104] Layers other than the two layers of the insulating film 17 and the heat fusion bonding portion 19 can be appropriately formed on the outer periphery of the conductor strand 15a. In addition, the insulating film 17 and the heat fusion bonding portion 19 are not limited to being continuously formed in the length direction, and linear shapes or spiral shapes, dot patterns, intermittent formations, etc. can be conceived, for example, in the length direction of the heater wire 11. However, from the perspective of adhesive strength, it is preferable to continuously form the insulating film 17 and the heat fusion bonding portion 19 in the length direction.

[0105] In addition, for the heater wire 11 obtained as described above, in a flexibility test of performing a 90-degree bend with a curvature radius six times its own diameter, the number of bending attempts until at least one conductor strand breaks is preferably 20,000 times or more.

[0106] The base material 31 is not limited to the foamed polyurethane resin, and various polymer foams (for example, foamed resin sheets, foamed rubber sheets, etc. made of other materials) can also be conceived. In particular, polymer foams including voids and having excellent stretchability are preferred, and preferably, the hardness thereof is adjusted so that the irregularities of the heater wire do not appear on the surface. In addition, the method of adjusting the hardness includes adjusting the foaming rate, changing the bubble state to closed cells or open cells, and using materials having hardness according to the purpose. The materials can be selected from various resins, rubbers, thermoplastic elastomers, etc., such as polyurethane resin, chloroprene rubber, silicone resin, silicone rubber, neoprene, diene rubber, nitrile rubber, natural rubber, polyethylene resin, polypropylene resin, vinyl chloride resin, and ethylene-vinyl acetate copolymer. As the base material 31, in addition to the above, various materials such as non-woven fabrics, woven fabrics, paper, aluminum foil, mica plates, resin sheets, and stretched porous materials can also be used. The base material 31 is preferably flame-retardant, and an appropriate mixture of flame-retardant fibers and flame retardants is preferably used. In addition, a plurality of base materials 31 can be laminated and used. In such a case, different materials or the same materials with different porosities, etc. can be used as each base material 31.

[0107] As sutures, various known thread materials can be used. Examples include fibers configured so that their core materials are monofilaments, multifilaments, spun yarns, fiber materials thereof, or organic polymer materials constituting fiber materials of inorganic fibers (e.g., glass fibers) or organic fibers (polyethylene terephthalate and other polyester fibers, aliphatic polyamide fibers, aromatic polyamide fibers, fully aromatic polyester fibers, etc., polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, polylactic acid fibers, and fluororesin fibers), and the core material is coated with a thermoplastic organic polymer material around it. When the linear body is welded by applying heat and pressure, the suture may also melt and form a suture mark, or the suture may not melt and remain. When the suture melts, it can be expected that the linear body will be welded to the substrate due to the suture mark; when the suture remains, it can be expected that the linear body will be fixed to the substrate by the suture. In addition, there is no particular limitation on the suture method. When sutures are performed using a suture machine for sewing, different materials can be used as the surface thread 33 and the bottom thread 35, or the same material can be used. For example, it is conceivable that only the upper thread 33 may be melted during the welding of the linear body by applying heat and pressure. In such a case, although the lower thread 35 will remain, since the upper thread 33 has been melted, the lower thread 35 may also be removed. Since the welding step by applying heat and pressure is performed after the sewing step, and the sewing only needs to provide a fixation with the same strength as the temporary fixation, there is no particular restriction on the sewing spacing of the sewing thread. Although the fixing strength increases with the decrease in the sewing spacing, since a smaller sewing spacing also reduces the production speed, it is only necessary to sew with the minimum sewing spacing that allows the pattern shape of the linear body to be maintained. In addition, the sewing spacing can be changed according to the position. When the linear body is to be arranged in a pattern shape such as a serpentine shape, it is conceivable to adopt a smaller sewing spacing only in the curved portion of the serpentine to ensure that the serpentine shape remains intact.

[0108] In addition, when the heater wire 11 is disposed on the base material 31, in addition to the aspect of joining and fixing the heater wire 11 to the base material 31 by welding through application of heat and pressure, the heater wire 11 can also be fixed to the base material 31 by other aspects. For example, conceivable aspects include the following: energizing and heating the heater wire 11 to make the heater wire reach a temperature higher than the temperature during normal use, and using this heat to melt the heat fusion portion 19 so as to join and fix the heat fusion portion 19 to the base material 31; heating the conductor strand 15a by induction heating and using this heat to melt the heat fusion portion 19 to join and fix the heat fusion portion 19 to the base material 31; melting the heat fusion portion 19 made of a heat fusion material by hot air to join and fix the heat fusion portion 19; and clamping and fixing with a pair of base materials 31 while applying heat. In addition, when heat and pressure are applied to the base material 31, not only the pressure heating plate 57 is heated, but the hot press jig 45 can also be heated. In the process of doing so, assuming that the temperature of the pressure heating plate 57 and the temperature of the hot press jig 45 are different from each other, the compression ratio (in other words, the porosity) of the base material 31 can be changed.

[0109] In addition, the positional relationship between the first linear body and the second linear body when they are disposed can be selected in various ways according to the purpose. When both the first linear body and the second linear body are heater wires, for example, the first linear body can be disposed in a pattern that provides excellent instantaneous heating characteristics when starting up, and the second linear body can be disposed in a pattern that provides excellent thermal uniformity in a temperature equilibrium state. In such a case, it is preferable to minimize the overlapping area between the first linear body and the second linear body as much as possible. This is because, due to the diameters of the two linear bodies, the thickness of this overlapping area becomes larger, and since the two heater wires are very close to each other, this overlapping area may cause overheating. On the other hand, when the first linear body is a heater wire and the second linear body is a sensor wire for temperature detection, preferably the first linear body and the second linear body are arranged so that they overlap in the same pattern. This is because, since the position of the detection strand for detecting temperature is closest to the heating strand, temperature detection can be performed more directly. However, if there is a portion where the first linear body and the second linear body overlap each other, there is a possibility that the first linear body and the second linear body may be short-circuited in the above portion due to an external force. Therefore, it is preferable that the pattern of the first linear body and the pattern of the second linear body do not overlap each other.

[0110] In addition, as the adhesive layer, for example, various adhesive layers can be used, such as an adhesive layer made of a polymer acrylic pressure-sensitive adhesive and not using a tape substrate, an adhesive layer made by forming adhesives on both sides of a polypropylene film, or an adhesive layer made by forming adhesive layers on both sides of a nonwoven fabric or a woven fabric. An adhesive layer having sufficient flame retardancy to pass FMVSS No. 302 (flammability of interior materials) can improve the flame retardancy of the planar unit and is thus preferred. In addition, an adhesive layer made only of a pressure-sensitive adhesive is preferred so as not to impair the stretchability of the planar unit.

[0111] In the planar unit according to the present invention, another planar unit can be arranged so that they overlap each other. For example, the following planar unit can be produced: in this planar unit, the first linear body is a heater wire, and the second linear body is a shield wire, and another planar unit having only sensor wires arranged on the second linear body side of the planar unit. With this configuration, since a shield wire is provided between the heater wire and the sensor wire, electromagnetic waves from the heater wire are blocked by the shield wire, preventing the sensor wire from being affected.

[0112] As an application of the planar unit 1 according to the present invention, in addition to the steering wheel as described above Figure 18 shown, the planar unit 1 can also be used for various applications. For example, it can be envisaged that the planar unit 1 configured as described above is embedded and arranged in a vehicle seat 81 in the state as Figure 19 shown. Figure 19 The planar unit 1 in [] is attached to the skin cover 83 or the seat cushion 85 and arranged between the skin cover 83 and the seat cushion 85. In such a case, the planar unit 1 is a heater unit in which the linear body is a heater wire and will be used as a heater device for the seat. In addition, it can be envisaged that a sensor unit in which the linear body is a capacitance sensor wire can be used to detect the seat occupancy state.

[0113] Industrial Applicability

[0114] As described in detail above, the present invention can prevent a user from feeling discomfort during a steering operation. Such a planar unit can be suitably used, for example, as a heater unit for heating a steering wheel portion or a seat, as a temperature sensor unit for detecting the temperature of the steering wheel or the seat, or as a capacitance sensor unit for detecting the gripping state of the steering wheel or the occupancy state of the seat, in a steering wheel or a seat used in an automobile, a ship, various transportation vehicles, various agricultural vehicles, and various civil engineering and construction vehicles. In addition, taking advantage of the fact that the planar unit according to the present invention has no irregularities and is flat in the linear body portion, the planar unit can be used for purposes other than the steering wheel and the seat. For example, it is conceivable to apply the planar unit to an electric blanket, an electric heating carpet, a heated toilet seat, a heater for an anti-fog mirror, a cooking appliance, a heater for floor heating, a heater for clothing, various planar temperature detectors, capacitance sensors, and the like.

[0115] This application is based on and claims the priority benefit of a Japanese patent application with application number 2022-208899, filed on December 26, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0116] List of Reference Numerals

[0117] 1 Planar unit

[0118] 11 Heater wire (first linear body)

[0119] 13 Core wire

[0120] 15a Conductor strand

[0121] 15b Insulating film

[0122] 19 Heat fusion joint

[0123] 21 Sensor wire (second linear body)

[0124] 23 Core wire

[0125] 25a Conductor strand

[0126] 25b Insulating film

[0127] 29 Heat fusion joint

[0128] 31 Base material

[0129] 33 Surface thread (suture)

[0130] 35 Bottom thread (suture)

[0131] 71 Steering wheel

[0132] 77 Wheel core material

[0133] 78 Cover material

[0134] 81 Vehicle seat

[0135] 83 Skin cover

[0136] 85 Seat cushion

Claims

1. A planar unit, the planar unit comprising a base material, a first linear body disposed on one surface of the base material, and a second linear body disposed on the other surface of the base material, the first linear body being one of a heater wire, a sensor wire, or a shielding wire, and the second linear body being one of a heater wire, a sensor wire, or a shielding wire, wherein the base material and the first linear body are coupled to each other by a suture; a heat-sealing portion is formed on the outermost layer of the second linear body, and the base material and the second linear body are heat-sealed together.

2. The planar unit according to claim 1, wherein a heat-sealing portion is formed on the outermost layer of the first linear body, and the suture is inserted into the heat-sealing portion of the first linear body.

3. The planar unit according to claim 2, wherein, The thickness of the positions where the first linear body and the second linear body are disposed in the base material is thinner so as to follow the shapes of the first linear body and the second linear body, and the suture is inserted into the heat-sealing portion of the first linear body and has a substantially flat shape.

4. The planar unit according to claim 1, wherein a heat-sealing portion is formed on the outermost layer of the first linear body, the planar unit includes a suture trace generated by melting the suture that couples the first linear body and the base material to each other, and the heat-sealing portion of the first linear body and the suture trace are flattened.

5. The planar unit according to claim 4, wherein, The thickness of the positions where the first linear body and the second linear body are disposed in the base material is thinner so as to follow the shapes of the first linear body and the second linear body, and the heat-sealing portion of the first linear body and the suture trace are flattened and have a substantially flat shape.

6. A steering wheel, the steering wheel comprising a planar unit according to any one of claims 1 to 5, a wheel core material, and a covering material, wherein, The planar unit is installed between the wheel core material and the covering material.

7. A method for manufacturing a planar unit, Among them, the first linear body is one of a heater wire, a sensor wire, or a shielding wire, and the second linear body is one of a heater wire, a sensor wire, or a shielding wire, the method comprising: fixing the first linear body to one surface of a base material by a suture; disposing the second linear body including the outermost layer on the other surface of the base material in a predetermined pattern shape, a heat-sealing portion being formed on the outermost layer of the second linear body; and applying heat and pressure to the base material, the first linear body, and the second linear body such that the thickness of the positions where the first linear body and the second linear body are disposed in the base material follows the shapes of the first linear body and the second linear body and the base material and the second linear body are fixed to each other using the heat-sealing portion.

8. The method for manufacturing a planar unit according to claim 7, Among them, the first linear body includes an outermost layer, a heat-sealing portion being formed on the outermost layer of the first linear body, the method comprising: when applying heat and pressure to the first linear body and the second linear body, inserting the suture into the heat-sealing portion of the first linear body to make the suture have a substantially flat shape; and fixing the base material and the second linear body to each other using the heat-sealing portion.

9. The method for manufacturing a planar unit according to claim 7, Among them, wherein the first linear body includes an outermost layer, and a heat-sealing portion is formed on the outermost layer of the first linear body, the method comprising: when heat and pressure are applied to the first linear body and the second linear body, melting the suture and the heat-sealing portion; flattening the suture mark generated by melting the suture and the heat-sealing portion so that the suture mark and the heat-sealing portion have a substantially flat shape; and fixing the substrate and the first linear body to each other using the heat-sealing portion.

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