Planar unit with linear body and its application

Abstract

To provide a planar unit and a steering wheel that do not make a user feel uncomfortable during steering operation, etc., and have excellent productivity.SOLUTION: A planar unit includes a base material and a linear body disposed on the base material, the linear body is either a heater wire or a sensor wire, or both, a heat-fused portion is formed on the outermost layer of the linear body, the planar unit includes a sewing thread that connects the linear body and the base material, the sewing thread has bitten into the heat-fused portion of the linear body, or there is a sewing thread trace formed by melting the sewing thread connecting the linear body and the base material, and the heat-fused portion of the linear body and the sewing thread trace are flattened. There is provided a steering wheel in which the planar unit is installed between a wheel core material and a covering material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a planar unit including a heater unit for warming the wheel portion of a steering wheel used in, for example, an automobile or a ship, and a sensor unit for detecting the temperature and grip of the steering wheel, and in particular to a unit that does not cause a user to feel uncomfortable when operating the steering wheel, etc., and that is highly productive. [Background technology]

[0002] It has been proposed to install a heater unit on the wheel portion of a steering wheel to warm the driver's hands in cold weather. A steering wheel consists of a wheel portion, spokes, and a boss portion. The wheel portion is formed from a wheel core material made of a metal core covered with urethane resin or the like and a covering material made of synthetic resin, textile products, leather, or the like. The heater unit is installed between the wheel core material and the covering material and is connected to lead wires that pass through the spokes and boss portion to receive power.

[0003] Known heater units installed in steering wheels include those in which a heater wire is arranged in a predetermined pattern on a substrate, as shown in Patent Documents 1 to 4. Various types of foamed resin sheets, foamed rubber sheets, rubber sheets, nonwoven fabrics, woven fabrics, etc. are disclosed as substrates. Related art is also disclosed in Patent Document 5, for example.

[0004] Examples of sensor units include those that function as capacitance sensors or temperature sensors. Capacitance sensors are used in touch panels, seat occupancy detectors, and the like. In particular, so-called two-electrode capacitance sensors are widely used in a variety of applications due to their excellent detection sensitivity. When a human body approaches two insulated electrodes in close proximity, the capacitance value between the two electrodes changes, and this change in capacitance is detected. This technology is being studied, for example, for detecting grip on a steering wheel. Examples of sensor units using linear capacitance sensors include Patent Document 6. Temperature sensors are known to be used as temperature detection means for heating appliances such as electric carpets and electric blankets. These sensors have a structure in which a sensor wire is wound around a central core wire and the outer periphery is covered with a sheath. Temperature detection is performed by detecting changes in the resistance value of the sensor wire due to temperature. This sensor wire is used, for example, near a heat source such as a heater wire to detect the temperature of the heater wire, or in a serpentine shape to detect temperature as a surface. An example of a sensor unit using a linear temperature sensor is disclosed in Patent Document 7. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4202071: Kurabe [Patent Document 2] International Publication WO2014 / 104000: Toyoda Gosei, Kurabe [Patent Document 3] Patent No. 6468701: Kurabe [Patent Document 4] Patent No. 6760941: Kurabe [Patent Document 5] Patent No. 3991750: Matsushita Electric Industrial Co., Ltd. [Patent Document 6] Patent No. 6851730: Kurabe [Patent Document 7] Patent No. 5562678: Kurabe DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] For example, in the heater units described in Patent Documents 2 to 4, the thickness of the substrate at the location where the heater wire is disposed is thinned to conform to the shape of the heater wire, resulting in a flat shape. When such a heater unit is installed in a steering wheel, the heater wire usually causes no irregularities, and the user does not feel any discomfort when steering. However, in recent years, when installing a heater unit in a steering wheel, the heater unit has been strongly stretched during installation to prevent wrinkles. Furthermore, to improve the heating efficiency of the heater unit, it is also required to place the surface on which the heater wire is disposed on the covering material side of the steering wheel. Furthermore, heater units can be installed in steering wheels using various manufacturing methods, such as attaching the heater unit to the covering material side beforehand and then assembling the heater unit and the covering material together with the wheel core material, or attaching the heater unit to the wheel core material beforehand and then covering it with the covering material. The appearance of unevenness varies depending on the method of assembling such a heater unit, and no matter what method is used, it is necessary to have a system that does not cause unevenness due to the heater wire and does not cause the user to feel uncomfortable when steering.

[0007] Furthermore, the heater units described in Patent Documents 1 to 4 are configured such that the heater wire 1 is arranged in a predetermined pattern on a substrate and bonded and fixed thereto. The manufacturing method is as follows: First, a hot press jig equipped with a mechanism having multiple vertically movable locking members is used. The heater wire 1 is hooked onto these locking members and arranged in a predetermined pattern. Next, the substrate is placed on the heater wire. Then, a press hot plate is lowered to apply heat and pressure to the heater wire and substrate, thereby bonding and fixing them. With this manufacturing method, the number of locking members required increases significantly as the pattern shape becomes finer. For example, a pattern shape requiring high density and high output, such as a heater unit for a steering wheel, requires more than 1,000 locking members. Every time a design change is made, such as a change to the outer shape of the substrate or the pattern shape of the heater wire, the position and arrangement of these more than 1,000 locking members must be redesigned, and there has been a demand for a method to eliminate this labor.

[0008] On the other hand, the heater unit described in Patent Document 5 uses a sewing machine or other machine to sew a heater wire to a substrate with a sewing thread consisting of an upper thread and a lower thread. In this heater unit, the heater wire is fixed to the substrate only with the sewing thread. Therefore, repeated loads during use can gradually cause the thread to fray or break, resulting in the heater wire moving. If the heater wire moves, not only will the seat not be heated uniformly, but there is also the risk of localized abnormal heating. There is also the problem of the heater wire slipping out of the sewing thread. In this case, the heater wire may bend at an acute angle at the slipped portion, potentially causing a break. Furthermore, the overlapping portion of the sewing thread adds thickness. As described above, heater units used in steering wheels are strongly required to have a smooth surface without any irregularities, and the feel of the sewing thread has been a problem.

[0009] The above-mentioned problems also occur in planar sensor units in which linear sensor wires are disposed on a substrate, as shown in Patent Documents 6 and 7.

[0010] The present invention has been made to solve the problems of the prior art, and its purpose is to provide a surface unit that does not cause the user to feel uncomfortable when operating the steering wheel, etc., and that is highly productive. [Means for solving the problem]

[0011] In order to achieve the above object, a planar unit according to the present invention comprises a base material and a linear body disposed on the base material, Condition The planar unit has a body made of either a heater wire or a sensor wire, or both, and has a heat-sealed portion formed on the outermost layer of the linear body, a sewing thread connecting the linear body and the base material, and the sewing thread is embedded in the heat-sealed portion of the linear body. In addition, it is thought that the thickness of the base material at the location where the linear body is arranged is thin to conform to the shape of the linear body, and that the sewing thread penetrates into the heat-sealed portion of the linear body, resulting in a generally flat shape. A planar unit according to another aspect of the present invention comprises a base material and a linear body disposed on the base material, Condition a planar unit in which the linear body is either a heater wire or a sensor wire, or both, and a heat-sealed portion is formed on the outermost layer of the linear body; The linear body has a sewing thread mark formed by melting the sewing thread connecting the linear body and the base material, and the heat-fused portion of the linear body and the sewing thread mark are flattened. In addition, it is thought that the thickness of the portion of the base material where the linear body is arranged is thin to conform to the shape of the linear body, and the heat-sealed portion of the linear body and the sewing marks are flattened, resulting in a generally flat shape. The steering wheel according to the present invention comprises the above-mentioned planar unit, a wheel core material, and a covering material, with the planar unit being disposed between the wheel core material and the covering material. A method for manufacturing a planar unit according to the present invention includes the steps of: fixing a linear body having a heat-sealed portion formed on the outermost layer to a base material with a sewing thread; and applying heat and pressure to the base material and the linear body to thin the thickness of the portion of the base material where the linear body is disposed so as to conform to the shape of the linear body, causing the sewing thread to bite into the heat-sealed portion of the linear body, thereby forming a generally flat shape, and fixing the base material and the linear body with the heat-sealed portion. Condition The body may be either a heater wire or a sensor wire, or both. A method of manufacturing a sheet unit according to another aspect of the present invention includes the steps of: fixing a linear body having a heat-sealed portion formed on the outermost layer to a base material with a sewing thread; and applying heat and pressure to the base material and the linear body to thin the thickness of the portion of the base material where the linear body is disposed so as to conform to the shape of the linear body, fusing the sewing thread and the heat-sealed portion, flattening the sewing thread mark formed by the melting of the sewing thread and the heat-sealed portion to form a generally flat shape, and fixing the base material and the linear body with the heat-sealed portion. Condition The body may be either a heater wire or a sensor wire, or both. [Effects of the Invention]

[0012] According to the present invention, not only are there no irregularities caused by linear objects such as heater wires, but there are also no irregularities caused by sewing threads, and the planar unit has a flat shape. Therefore, even if the planar unit is assembled to the steering wheel by various methods, no irregularities caused by linear objects are visible, and the user does not feel any discomfort when steering. Furthermore, since the manufacturing method can be such that the linear body is placed on the base material while being sewn together using a sewing machine or other machine, a large number of fastening members are not required, which significantly reduces the effort required for design changes and improves productivity. Furthermore, since the linear body is fastened and fixed to the base material by the sewing thread, and then the base material and the linear body are fixed by thermal fusion, the flatness of the planar unit can be further improved. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a plan view showing the configuration of a planar unit according to the present invention. [Figure 2] 1 is an enlarged cross-sectional view schematically illustrating a main part of a planar unit according to a first embodiment of the present invention. [Figure 3] 3A and 3B are enlarged cross-sectional views schematically showing a main part of a planar unit according to an embodiment of the present invention during manufacturing. [Figure 4] 1 is a diagram showing an embodiment of the present invention, illustrating the configuration of a hot press heater manufacturing apparatus. FIG. [Figure 5] 3 is a cross-sectional photograph of a main part of the planar unit according to the first embodiment of the present invention. [Figure 6] 10 is a cross-sectional photograph of a main part of a planar unit according to a second embodiment of the present invention. [Figure 7] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 8] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 9] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 10] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 11] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 12] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 13] FIG. 2 is a partially cutaway side view showing an example of a heater wire used in the present invention. [Figure 14] FIG. 2 is a partially cutaway side view showing an example of a sensor wire used in the present invention. [Figure 15] FIG. 2 is a partially cutaway side view showing an example of a sensor wire used in the present invention. [Figure 16] 1 is a partially cutaway perspective view showing a state in which a planar unit according to the present invention is embedded in a steering wheel. [Figure 17] 1 is a partially cutaway perspective view showing a state in which a planar unit according to the present invention is embedded in a vehicle seat. BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. These embodiments show examples in which a heater wire is used as the linear body and the planar unit of the present invention is applied to a steering heater for a vehicle.

[0015] First, a first embodiment will be described with reference to FIGS. 1 and 2. The configuration of a heater wire 1 in this first embodiment will be described. The heater wire 1 in this first embodiment has a configuration as shown in FIGS. 7 and 8. First, the core wire 3 is formed of an aromatic polyamide fiber bundle having an outer diameter of approximately 0.2 mm. Five conductor wires 5a, which are hard tin-containing copper alloy wires having an element diameter of 0.08 mm, are wound helically around the core wire 3 at a pitch of approximately 1.0 mm. As shown in FIGS. 7 and 8, an insulating coating 5b is formed around the conductor wires 5a. The insulating coating 5b is formed of an inner layer 5c made of polyurethane resin and an outer layer 5d made of polyamide-imide resin. The inner layer 5c of the insulating coating 5b is formed by applying polyurethane varnish around the conductor wires 5a and drying it to form a layer with a thickness of 4 μm. Next, the outer layer 5d is formed by applying polyamide-imide varnish around the inner layer 5c and drying it to form a layer with a thickness of 4 μm. The core wire 3 around which the conductor wire 5a is wound is covered with an insulating layer. The insulating layer is formed by extrusion coating polyethylene resin containing a flame retardant to a thickness of 0.2 mm. In this embodiment, the polyethylene resin of the insulating layer functions as the heat-sealed portion 9. The heater wire 1 has a finished outer diameter of 0.8 mm. The core wire 3 is effective in terms of increasing flexibility and tensile strength. It is also possible to align or twist multiple conductor wires without using the core wire 3.

[0016] Next, the structure of the substrate 11 to which the cord-shaped heater 1 having the above-mentioned structure is adhered and fixed will be described. The substrate 11 in the first embodiment has an apparent density of 40 kg / m 3 The base material 11 is made of a foamed polyurethane resin having a hardness of 220N (JIS K6400) and a thickness of 8 mm (JIS K7222 compliant). Such a base material 11 is cut into a desired shape by a known method such as die cutting.

[0017] Next, a configuration for disposing the heater wire 1 in a predetermined pattern on the substrate 11 will be described. The substrate 11 is placed on a movable table, and the heater wire 1 is placed on a heater wire supplying machine attached to a sewing machine. The heater wire 1 is supplied immediately in front of the needle bar unit of the sewing machine, and in synchronization with this, the movable table moves in a predetermined pattern, and at the same time, the heater wire 1 is sewn to the substrate 11 by the sewing machine. In this way, the heater wire 1 is disposed in a serpentine shape on the substrate 11. FIG. 3 is an enlarged cross-sectional view showing a main part of the planar unit 21 in a state in which the heater wire 1 has been sewn to the surface of the substrate 11. The sewing thread consists of an upper thread 23 and a lower thread 25. The upper thread 23 wraps around almost the entire circumference of the heater wire 1 and is entangled with the lower thread 25 on the back side to be sewn to the substrate 11. The upper thread 23 is a polyester filament thread of 165 dtex, and the lower thread 25 is a polyester filament thread of 165 dtex. The stitching pitch is 2 mm in the straight portion of the serpentine shape and 1 mm in the curved portion of the serpentine shape.

[0018] Next, a configuration for arranging the heater wire 1 in a predetermined pattern on the substrate 11 and bonding and fixing it thereto will be described. FIG. 4 shows the configuration of a hot-press heater manufacturing apparatus 13 for bonding and fixing the cord-shaped heater 10 to the substrate 11. First, the substrate 11 to which the heater wire 1 is sewn is placed in a hot-press jig 15. In this state, a press hot plate 17 descends to press the substrate 11 against the cord-shaped heater 10. At this time, the press hot plate 17 applies heat and pressure to the substrate 11 and the cord-shaped heater 10 at 230°C for 5 seconds, for example. As a result, the heat-sealable portion 9 of the cord-shaped heater 10 and the heat-sealable fiber of the substrate 11 are both heated and pressurized and fused to each other. As a result, the cord-shaped heater 10 and the substrate 11 are bonded and fixed together. At this time, the hot-press jig 15 may also be heated.

[0019] By performing the above steps, a planar unit 21 as shown in FIGS. 1 and 2 can be obtained. Note that FIG. 2 is an enlarged cross-sectional view of a main portion of FIG. 1. Because the base material 11 is compressed by the press hot plate 17, stronger pressure is applied to the portion of the base material 11 where the heater wire 1 is to be disposed. As a result, the portion of the base material 11 where the heater wire 1 is to be disposed is denser and thinner than other portions, conforming to the shape of the heater wire 1. As a result, the surface of the planar unit 21 where the heater wire 1 is to be disposed is flat, with no irregularities, even in the portion where the heater wire 1 is to be disposed. Furthermore, the planar unit 21 obtained in this manner can have improved mechanical strength because the base material 11 is compressed and dense.

[0020] Furthermore, the upper thread 23 bites into the heat-sealed portion 9 of the heater wire 1 due to the heating and pressurizing of the press hot plate 17. As a result, the protrusion caused by the sewing thread (upper thread 23) disappears, and the surface of the planar unit 21 on which the heater wire 1 is disposed becomes flat. Fig. 5 shows a cross-sectional photograph of the planar unit 21 according to the first embodiment. As shown in Fig. 5, it can be seen that the upper thread 23 bites into the heat-sealed portion 9 of the heater wire 1.

[0021] Furthermore, the heater wire 1 is fastened and fixed to the base material 11 with the sewing threads (upper thread 23 and lower thread 25), and then the base material 11 and the heater wire 1 are fixed by thermal fusion, which further increases the flatness of the planar unit 21.

[0022] The thickness of the planar unit 21 obtained in the first embodiment was 2.0 mm, the thickness of the substrate 11 in the area where the heater wire 1 was disposed was 1.4 mm, and the thickness of the substrate 11 in the area where the heater wire 1 was not disposed was 2.0 mm. The apparent density of the substrate 11 in the area where the heater wire 1 was not disposed was 160 kg / m 3 (JIS K7222 compliant), and hardness ASKER C 15 (JIS K7312 compliant).

[0023] The heat-sealed portion 9 on the periphery of the heater wire 1 was deformed and flowed by the application of heat and pressure, and some of it penetrated into the gaps (pores) in the substrate 11. The area where the heater wire 1 was disposed was generally flat, with no irregularities compared to the surrounding thickness. A thickness variation within a range of about ±10% can be considered generally flat, meaning that the thickness is essentially almost constant. A thickness variation within a range in which the user does not perceive irregularities visually or tactilely can also be considered generally flat.

[0024] In the planar unit 21 obtained as described above, both ends of the heater wire 1 are drawn out and connected to lead wires 27, and the heater wire 1, temperature control device 29, and connector (not shown) are connected by these lead wires 27. The temperature control device is disposed on the heater wire 1, and controls the temperature of the planar unit by the heat generated by the heater wire 1. The temperature control device is then connected to the vehicle's electrical system (not shown) via the connector.

[0025] The planar unit 21 having the above-described configuration is installed on a steering wheel 71 in the state shown in Fig. 16. This steering wheel 71 is made up of a wheel portion 72, spoke portions 73, and a boss portion 74, and the planar unit 21 is installed between a wheel core material 77 and a covering material 78 of the wheel portion 72.

[0026] An adhesive layer (not shown) is formed on the substrate 11 to bond the planar unit 21 to the covering material 78 of the steering wheel or to bond the planar unit 21 to the wheel core material 77 of the steering wheel. The adhesive layer is preferably formed by first forming an adhesive layer consisting only of an adhesive on a release sheet, and then transferring the adhesive layer from the release sheet to the surface of the substrate 11. This prevents the adhesive from penetrating into the interior of the substrate 11, and results in an adhesive layer being formed only on the surface of the substrate 11.

[0027] When installing the planar unit 21 on the steering wheel, one of the following manufacturing methods 1 to 4 was used. (Method 1) In manufacturing method 1, the planar unit 21 and the covering material 78 are bonded together, and at that time, the surface side on which the heater wire 1 is disposed is bonded to the covering material 78. Thereafter, the covering material 78 to which the planar unit 21 is bonded is used to cover the wheel core material 77. (Method 2) In manufacturing method 2, the planar unit 21 and the covering material 78 are bonded together, and at that time, the surface side on which the heater wire 1 is not disposed is bonded to the covering material 78. Thereafter, the covering material 78 to which the planar unit 21 is bonded is used to cover the wheel core material 77. (Method 3) In manufacturing method 3, the planar unit 21 and the wheel core material 77 are bonded together, with the surface side on which the heater wire 1 is disposed being bonded to the wheel core material 77. Thereafter, the wheel core material 77 to which the planar unit 21 is bonded is covered with a covering material 78. (Method 4) In manufacturing method 4, the planar unit 21 and the wheel core material 77 are bonded together, with the surface side on which the heater wire 1 is not disposed being bonded to the wheel core material 77. Thereafter, the wheel core material 77 to which the planar unit 21 is bonded is covered with a covering material 78.

[0028] (Embodiment 2) In the above-described embodiment 1, the sewing threads were polylactic acid fiber with an outer diameter of 0.165 mm for the upper thread 23 and low-melting-point polyethylene thread of 110 dtex for the lower thread 25, and the other conditions were the same as those of embodiment 1 to obtain the planar unit 21.

[0029] In the second embodiment, the upper and lower threads are melted by the application of heat and pressure by the hot press heater manufacturing apparatus 13, and sewing marks are formed near the heater wire of the planar unit. These sewing marks are also flattened by the application of heat and pressure, so the surface of the planar unit 21 on which the heater wire 1 is disposed has a flat shape. Figure 6 shows a cross-sectional photograph of the planar unit 21 according to the second embodiment. As can be seen in Figure 6, the thermally fused portion of the heater wire and the sewing marks have been flattened.

[0030] (Embodiment 3) In the first embodiment described above, a sensor wire was used as the linear body, and the other conditions were the same as in the first embodiment to obtain a sheet unit 21. The sensor wire 31 in the third embodiment has a configuration as shown in FIGS. 14 and 15. First, the core wire 33 is formed of an aromatic polyamide fiber bundle having an outer diameter of approximately 0.2 mm. Two conductor wires 35a, which are hard tin-containing copper alloy wires having an element diameter of 0.08 mm, are wound around the core wire 33 in a spiral shape with a pitch of approximately 1.0 mm. As shown in FIGS. 14 and 15, an insulating coating 35b is formed around the conductor wires 35a. The insulating coating 35b is formed of an inner layer 35c made of polyurethane resin and an outer layer 35d made of polyamideimide resin. The inner layer 35c of the insulating coating 35b is formed by applying polyurethane varnish around the conductor wires 35a and drying it to form a layer with a thickness of 4 μm. Next, the outer layer 35d is formed by applying polyamideimide varnish to the outer periphery of the inner layer 35c and drying it to form a layer with a thickness of 4 μm. The outer periphery of the core wire 33 around which the conductor wire 35a is wound is covered with an insulating layer. The insulating layer is formed by extrusion coating polyethylene resin containing a flame retardant to a thickness of 0.2 mm. In this embodiment, the polyethylene resin of the insulating layer functions as the heat-sealed portion 39. The finished outer diameter of the heater wire 31 described above is 0.8 mm. This sensor wire 31 detects the electrostatic capacitance value between two conductor wires 35a.

[0031] The planar units 21 according to the first to third embodiments obtained as described above were installed on steering wheels 71 as shown in Fig. 16 using the methods shown in manufacturing methods 1 to 4. In this state, the steering wheels were put into actual use and checked for any discomfort. To check, 10 users gripped the steering wheel and performed steering operations on the left and right 10 times each, and were asked whether they felt any unevenness, and the number of people who answered that they felt any discomfort was surveyed.

[0032] With regard to the planar units of the first to third embodiments, no user responded that they felt uncomfortable when they were attached to the steering wheel by any of the manufacturing methods.

[0033] The present invention is not limited to the above embodiment. The linear body may be a heater wire 1 or a sensor wire 31. If the heater wire 1 is used, the linear body may be a heater wire 1 or a sensor wire 31. Condition The body unit 31 becomes a heater unit, and if a sensor wire 31 is used, the wire Condition The body unit 31 is a sensor unit. The sensor wire 31 can be used as a capacitance sensor or other sensors such as a temperature sensor. As a type of temperature sensor, the linear body can be made of solder wire and used as an abnormal temperature detection unit. In terms of detecting radio waves, the linear body can also be used as an antenna wire and used as an antenna unit.

[0034] As the heater wire 1, various conventionally known cord-shaped heaters can be used, and for example, the following configurations can be used. 1. As in the above embodiment shown in FIG. 7, first, a plurality of conductor wires 5a covered with an insulating coating 5b are twisted or pulled together and wound around a core wire 3, and then the outer periphery of the conductor wires 5a is covered with a heat-sealing portion 9 to form the heater wire 1. 2. As shown in FIG. 9, the heater wire 1 is formed by twisting together a plurality of conductor wires 5a covered with an insulating coating 5b. 3. As shown in FIG. 10, a heater wire 1 is formed by arranging a plurality of conductor wires 5a covered with an insulating coating 5b. 4. As shown in FIG. 11, the heater wire 1 is formed by alternately arranging conductor wires 5a covered with an insulating coating 5b and conductor wires 5a not covered with an insulating coating 5b. 5. As shown in FIG. 12, the heater wire 1 is formed by arranging the conductor wires 5a coated with the insulating coating 5b in a parallel arrangement with the number of the conductor wires 5a coated with the insulating coating 5b increased compared to that shown in FIG. 11. 6. As shown in FIG. 13, a heater wire 1 having an insulating layer 7 formed separately from the heat-sealed portion 9. Various other configurations are possible for the heater wire 1. The heater wire 1 can also be formed by twisting together the core wire 3 and the conductor wires 5a. The same applies when a sensor wire 31 is used instead of the heater wire 1.

[0035] Examples of the core wire 3 include monofilaments, multifilaments, and spun organic fibers such as inorganic fibers like glass fibers, polyester fibers like polyethylene terephthalate, aliphatic polyamide fibers, aromatic polyamide fibers, and wholly aromatic polyester fibers, or fibers having a core made of these fiber materials or an organic polymer material constituting these fiber materials and a thermoplastic organic polymer material covering the periphery. Furthermore, when a heat-shrinkable and heat-fusible core wire 3 is used, if a conductor wire 5a breaks and abnormal heating occurs, the core wire 3 melts and is cut, and also shrinks. When the core wire 3 shrinks, the conductor wires 5a wound around the core wire 3 follow the movement of the core wire 3, causing the ends of the broken conductor wire 5a to separate. This prevents the ends of the broken conductor wire 5a from repeatedly coming into contact and separating. Furthermore, the ends of the broken conductor wire 5a do not come into contact with each other over a small area, such as a point contact. This prevents abnormal heat generation. Furthermore, if the conductor wires 5a are insulated by the insulating coating 5b, the core wire 3 does not need to be made of an insulating material. For example, a stainless steel wire or a titanium alloy wire can be used as the core wire 3. However, since there is a possibility that the conductor wires 5a may break, it is preferable that the core wire 3 be made of an insulating material.

[0036] The conductor wires 5a may be conventionally known, such as copper wire, copper alloy wire, nickel wire, iron wire, aluminum wire, nickel-chromium alloy wire, and iron-chromium alloy wire. Examples of copper alloy wires include tin-copper alloy wire, copper-nickel alloy wire, and silver-bearing copper alloy wire in which a copper solid solution and a copper-silver eutectic are fibrous. Among these, copper wire or copper alloy wire is preferred from the viewpoint of cost-performance balance. These copper wires and copper alloy wires are available in both soft and hard varieties. From the viewpoint of flex resistance, hard wires are particularly preferred over soft wires. Hard copper wires and hard copper alloy wires are formed by elongating individual metal crystal grains in the processing direction through cold processing such as wiredrawing, resulting in a fibrous structure. When such hard copper wires or hard copper alloy wires are heated above their recrystallization temperature, the processing strain generated within the metal crystals is eliminated, and crystal nuclei that serve as starting points for new metal crystals begin to appear. These crystal nuclei develop, and recrystallization occurs, successively replacing the old crystal grains, leading to further growth of the crystal grains. A soft copper wire or soft copper alloy wire is a wire in this state of crystal grain growth. Although these soft copper wires or soft copper alloy wires have higher elongation and electrical resistance than hard copper wires or hard copper alloy wires, they have lower tensile strength, and therefore lower bending resistance than hard copper wires or hard copper alloy wires. As such, hard copper wires or hard copper alloy wires become soft copper wires or soft copper alloy wires with low bending resistance through heat treatment, so it is preferable to carry out processing with as little thermal history as possible. Hard copper wires are defined in JIS-C3101 (1994), and soft copper wires are defined in JIS-C3102 (1984). Soft copper wires are defined as those with an elongation of 15% or more for an outer diameter of 0.10 to 0.26 mm, 20% or more for an outer diameter of 0.29 to 0.70 mm, 25% or more for an outer diameter of 0.80 to 1.8 mm, and 30% or more for an outer diameter of 2.0 to 7.0 mm. Tin-plated copper wires are also included. Tin-plated hard copper wires are defined in JIS-C3151 (1994), and tin-plated soft copper wires are defined in JIS-C3152 (1984). Various cross-sectional shapes can be used for the conductor wires 5a, and they are not limited to the commonly used circular cross-sections; so-called rectangular wires may also be used.

[0037] When the linear body is used as a temperature sensor wire, the conductor wire 35a 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, nickel-chromium alloy wire, copper-nickel alloy, and iron-chromium alloy wire, as well as carbon fiber wire and conductive resin wire. Among these, materials with a positive characteristic temperature coefficient are preferred. Nickel wire and platinum wire, which have particularly large coefficients, are preferred. Materials with a positive characteristic temperature coefficient increase in resistance as the temperature rises. Therefore, an increase in resistance is deemed to be an abnormal temperature, and the control method stops the flow of current. Therefore, if the conductor wire 35a breaks, the resistance value becomes infinite, and the flow of current is stopped, just as if an abnormal temperature occurred. This is an extremely reliable method when viewed as a safety device.

[0038] When winding the conductor wires 5a around the core wire 3, among the above-mentioned materials for the conductor wires 5a, those with a small amount of springback when wound are preferred. For example, a silver-copper alloy wire, in which a copper solid solution and a copper-silver eutectic are fibrous, has excellent tensile strength and bending strength, but is prone to springback when wound. Therefore, when winding the conductor wires 5a around the core wire 3, the conductor wires 5a are likely to lift or break due to excessive winding tension. Furthermore, they are prone to twisting after processing, making them undesirable. In particular, when the conductor wires 5a are coated with an insulating coating 5b, the insulating coating 5b also exerts a restoring force. Therefore, it is important to select a conductor wire 5a with a small restoring rate to compensate for the restoring force of the insulating coating 5b.

[0039] The insulating coating 5b covering the conductor wires 5a may be formed of two layers, an inner layer 5c and an outer layer 5d, as in the above embodiment, or may be formed of three or more layers, or may be a single layer. When a multi-layer structure is used, the thermal decomposition temperature of the material constituting the inner layer is preferably lower than the lower of the melting point and thermal decomposition temperature of the material constituting the outer layer. Here, the inner layer refers to a layer formed on the conductor wires 5a. The outer layer may be any layer located outside the inner layer, and therefore, it is possible to form another outer layer outside the outer layer or another intermediate layer between the inner and outer layers.

[0040] Examples of materials for the insulating coating 5b include polyurethane resin, polyamide resin, polyimide resin, polyamideimide resin, polyesterimide resin, nylon resin, polyesternylon resin, polyethylene resin, polystyrene resin, polypropylene resin, polyester resin, polybenzimidazole resin, vinyl chloride resin, fluororesin, and silicone resin. These materials may be used in combination, or may contain various known additives such as flame retardants and antioxidants. By combining these resins, the thermal decomposition temperature of the material constituting the inner layer is lower than the lower of the melting point and thermal decomposition temperature of the material constituting the outer layer. Materials for the inner layer may include polyurethane resin, vinyl chloride resin, polyacetal resin, polystyrene resin, polypropylene resin, polyester resins such as polymethyl methacrylate and polyethylene terephthalate, and polyvinyl alcohol. It is particularly preferable that the material for the inner layer be a thermosetting resin and the material for the outer layer be a thermosetting resin. Here, thermosetting resins also include crosslinkable materials. From the viewpoints of heat generation characteristics as a cord-shaped heater and ease of terminal processing such as soldering, it is preferable that the material of the inner layer is polyurethane resin or polyester resin, and the material of the outer layer is either polyimide resin, polyamide-imide resin, or silicone resin. It is particularly preferable that the material of the inner layer is polyurethane resin and the material of the outer layer is polyamide-imide resin. This polyurethane resin may be variously modified or compounded, such as imide-containing polyurethane.

[0041] The thickness of the insulating coating 5b is preferably 3 to 30% of the diameter of the conductor wires 5a. If the thickness is less than 3%, sufficient voltage resistance characteristics cannot be obtained, which may result in the omission of individually coating the conductor wires 5a. If the thickness is more than 30%, it becomes difficult to remove the insulating coating 5b when crimping a connection terminal, and the heater wire becomes unnecessarily thick.

[0042] When the conductor wires 5a are wound around the core material 3 by being paralleled or twisted, it is preferable to wind them parallel rather than twisted. This is because the diameter of the heater wire becomes smaller and the surface becomes smoother. In addition to being paralleled or twisted, it is also possible to braid the conductor wires 5a around the core material 3.

[0043] The heater wire 1 according to the present invention may also have an insulating coating 7 formed around the outer periphery of the conductor wire 5a (see, for example, Figure Z). This insulating coating 7 insulates other components from electrical current even if the conductor wire 5a breaks, and also insulates against high-temperature heat generation in the event of a spark. The insulating coating 7 may be formed by extrusion molding or the like, or a tubular insulating coating 7 may be applied in advance; there is no particular limitation on the method of formation. Forming the insulating coating 7 by extrusion molding is preferable because it fixes the position of the conductor wire 5a, preventing friction and bending of the conductor wire 5a due to misalignment, thereby improving bending resistance. The material constituting the insulating coating 7 may be appropriately selected depending on the manner of use and environment of the heater wire. Examples of suitable materials include polyolefin resins, polyester resins, polyurethane resins, aromatic polyamide resins, aliphatic polyamide resins, vinyl chloride resins, modified Noryl resins (polyphenylene oxide resins), nylon resins, polystyrene resins, fluororesins, synthetic rubber, fluororubber, ethylene-based thermoplastic elastomers, urethane-based thermoplastic elastomers, styrene-based thermoplastic elastomers, and polyester-based thermoplastic elastomers. In particular, flame-retardant polymer compositions are preferably used. Here, a flame-retardant polymer composition refers to a polymer composition having an oxygen index of 21 or higher in the flammability test according to JIS-K7201 (1999). A polymer composition having an oxygen index of 26 or higher is particularly preferred. To achieve such flame retardancy, a flame retardant or the like may be blended into the material constituting the insulating coating 7. Examples of the flame retardant include metal hydrates such as magnesium hydroxide and aluminum hydroxide, antimony oxide, melamine compounds, phosphorus compounds, chlorine-based flame retardants, bromine-based flame retardants, etc. These flame retardants may be subjected to appropriate surface treatment by known methods.

[0044] By forming a heat-sealing portion 9 on the outer periphery of the heater wire 1, the heater wire 1 can be heat-sealed to the substrate 11 by applying heat and pressure. When an insulating coating 7 is formed, the heat-sealing portion 9 is formed on the outer periphery of the insulating coating 7. The same materials as those used to form the insulating coating 7 can be used as materials for forming the heat-sealing portion 9. Among these, olefin-based resins, which have excellent adhesion to substrates, are preferred. Examples of olefin-based resins 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, ethylene-unsaturated ester copolymers are particularly preferred. Because ethylene-unsaturated ester copolymers have a molecular structure containing oxygen within the molecule, they generate less heat of combustion than resins such as polyethylene, which have a molecular structure consisting only of carbon and hydrogen, thereby suppressing combustion. Furthermore, due to their inherently high adhesiveness, they also have good adhesion to substrates. Furthermore, they are suitable for incorporating various flame retardants because their adhesiveness is not significantly reduced when inorganic powders or the like are incorporated. Examples of ethylene-unsaturated ester copolymers include ethylene-vinyl acetate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, and ethylene-butyl (meth)acrylate copolymer, and these may be used alone or in combination. Here, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. While any of these may be selected, it is preferable to use a material that melts at a temperature below the decomposition onset temperature or melting point of the material constituting the insulating coating 5b. Furthermore, polyester-based thermoplastic elastomers are examples of materials that have excellent adhesion to the substrate 11. Polyester-based thermoplastic elastomers include polyester-polyester and polyester-polyether types, with polyester-polyether types being preferred due to their higher adhesiveness. When heat-sealing the heater wire 1 to the substrate 11, the adhesive strength between the heater wire 1 and the substrate 11 is extremely important.If the adhesive strength is insufficient, the heater wire 11 will come off the substrate 11 during use, which will cause the heater wire 11 to bend unexpectedly, increasing the possibility of the conductor wires 5a breaking. If the conductor wires 5a break, not only will they no longer function as a heater, but there is also a risk of sparks due to chattering.

[0045] When forming the insulating coating 7, it is required that the melting point of the insulating coating 7 is higher than that of the heat-sealing portion 9. This prevents the shape of the insulating coating 7 from being substantially distorted when the heat-sealing portion 9 is fused by heating and pressurizing or the like, and allows sufficient insulating performance to be maintained. The melting point of the insulating coating 7 is preferably 215°C to 250°C, and the melting point of the heat-sealing portion 9 is preferably 100°C to 185°C. Furthermore, when forming the insulating coating 5b on the conductor wires 5a, it is preferable that the melting point of the insulating coating 7 is lower than that of the insulating coating 5b.

[0046] Furthermore, it is preferable that the material constituting the insulating coating 7 and the material constituting the heat-sealing portion 9 are the same polymer material. Here, the same polymer material refers to polymer materials having a common main chain structure, polymer materials having a common functional group, polymer materials differing only in molecular weight, copolymers having a common monomer unit, mixtures of common polymer materials, etc. Such materials ensure sufficient adhesion between the insulating coating 7 and the heat-sealing portion 9, preventing the heater wire from detaching from the substrate.

[0047] Other layers may be appropriately formed around the conductor wires 5a in addition to the two layers of the insulating coating 7 and the heat-sealed portion 9. The insulating coating 7 and the heat-sealed portion 9 are not limited to being formed continuously in the longitudinal direction, and may be formed in a linear or spiral pattern along the longitudinal direction of the heater wire 1, in a dotted pattern, or intermittently. However, from the viewpoint of adhesive strength, it is preferable that the insulating coating 7 and the heat-sealed portion 9 be formed continuously in the longitudinal direction.

[0048] Furthermore, the heater wire 1 obtained as described above is preferably bent 20,000 times or more until at least one of the conductor wires breaks in a bending test in which the heater wire 1 is bent by 90 degrees at a curvature radius six times its own diameter.

[0049] The substrate 11 is not limited to foamed polyurethane resin; various polymer foams, such as foamed resin sheets or foamed rubber sheets made of other materials, are also possible. A porous, highly elastic foam is particularly preferred, and one with adjusted hardness is preferred to prevent the heater wire from appearing on the surface. Methods for adjusting hardness include adjusting the foaming rate, forming closed or open cells, or using a material with a suitable hardness. Materials may be selected from a variety of resins, rubbers, and thermoplastic elastomers, including polyurethane resin, chloroprene rubber, silicone resin, neoprene rubber, diene rubber, nitrile rubber, natural rubber, polyethylene resin, polypropylene resin, vinyl chloride resin, and ethylene-vinyl acetate copolymer. Other materials that can be used for the substrate 11 include nonwoven fabric, woven fabric, paper, aluminum foil, mica plate, resin sheet, and expanded porous material. Flame-retardant substrates are preferred, and flame-retardant fibers and flame retardants are preferably mixed into the substrate 11. Furthermore, a plurality of base materials 11 may be stacked, and in this case, the respective base materials 11 may be made of different materials or have different porosities.

[0050] Various known thread materials can be used for the sewing thread. Examples include monofilaments, multifilaments, and spun organic fibers such as inorganic fibers like glass fiber, polyester fibers like polyethylene terephthalate, aliphatic polyamide fibers, aromatic polyamide fibers, wholly aromatic polyester fibers, polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, polylactic acid fibers, and fluororesin fibers, as well as these fiber materials, or fibers having a core made of an organic polymer material constituting these fiber materials and a thermoplastic organic polymer material covering the periphery. When fusing the linear body by heat and pressure, the sewing thread may melt along with the base material, leaving a sewing mark, or it may remain unmelted. If the sewing thread melts, fusing between the linear body and the substrate is expected through the sewing mark, while if the sewing thread remains, it is expected to fix the linear body and the substrate. There are also no particular limitations on the sewing method. When sewing with a sewing machine, the upper thread 23 and bobbin thread 25 may be made of different materials or the same material. For example, it is conceivable to melt only the upper thread 23 when fusing the linear body by heat and pressure. In this case, the lower thread 25 remains, but since the upper thread 23 is melted, it is possible to remove the lower thread 25. The stitching pitch of the sewing thread is not particularly limited, as it is sufficient to secure the linear body with a temporary fixation strength, since the fusing process by heat and pressure is performed after the sewing process. The smaller the stitching pitch, the stronger the fixation, but on the other hand, the slower the production speed. Therefore, it is sufficient to sew the linear body with the minimum stitching pitch that maintains the pattern shape. Furthermore, the stitching pitch may be varied from place to place. When arranging the linear body in a pattern shape such as a meandering shape, it is conceivable to use a small stitching pitch only in the curved portion of the meandering shape to prevent the meandering shape from shifting.

[0051] Furthermore, when the heater wire 1 is disposed on the substrate 11, the heater wire 1 may be fixed to the substrate 11 in a manner other than by bonding and fixing by fusion through heat and pressure. For example, the heater wire 1 may be heated by passing electricity through the heater wire 1 to a temperature higher than that in normal use, and the resulting heat melts the heat-sealed portion 9 to bond and fix it to the substrate 11; the conductor wires 5 may be heated by induction heating, and the resulting heat melts the heat-sealed portion 9 to bond and fix it to the substrate 11; the heat-sealed portion 9 made of a heat-sealing material may be melted by hot air to bond and fix it; or the substrate 11 may be sandwiched and fixed between a pair of substrates 11 while being heated. Furthermore, when heating and pressurizing the substrate 11, not only the press hot plates 17 but also the hot press jig 15 may be heated. In this case, it is also possible to change the compressibility of the substrate 11, i.e., the porosity, by setting the temperatures of the press hot plates 17 and the hot press jig 15 to different values.

[0052] The adhesive layer can be made of a variety of materials, including a polymeric acrylic adhesive that does not use a tape substrate, or a polypropylene film with an adhesive applied to both sides. If the adhesive layer alone has flame retardancy sufficient to pass the FMVSS No. 302 automotive interior materials combustion test, this is preferred, as it improves the flame retardancy of the sheet unit. Furthermore, an adhesive layer made solely of an adhesive is preferred to avoid impairing the stretchability of the sheet unit.

[0053] The surface unit 21 according to the present invention can be used for various purposes other than the steering wheel shown in FIG. Condition The body unit 21 may be embedded in a vehicle seat 81 as shown in Fig. 17. The planar unit 21 in Fig. 17 is attached to a seat cover 83 or a seat pad 85, and is disposed between the seat cover 83 and the seat pad 85. Here, the planar unit 21 is a heater unit with a heater wire as the linear body, and is used as a seat heating device. It may also be possible to use a sensor unit with a capacitance sensor wire as the linear body to detect the seating state. [Industrial Applicability]

[0054] As described above, the present invention can prevent a user from feeling any discomfort when steering. Such a planar unit can be used in steering wheels and seats of automobiles, ships, various transport vehicles, various agricultural vehicles, and various heavy machinery for civil engineering and construction, and can be suitably used as a heater unit for heating the steering wheel or seat, a temperature sensor unit for detecting the temperature of the steering wheel or seat, or a capacitance sensor unit for detecting the temperature of the steering wheel or the seat occupancy. Furthermore, by taking advantage of the fact that the linear body portion is flat and without any irregularities, the planar unit of the present invention can be used for purposes other than steering wheels and seats. For example, it can be applied to electric blankets, electric carpets, heated toilet seats, heaters for anti-fog mirrors, heating appliances, heaters for floor heating, heaters for clothing, various planar temperature detectors, capacitance detectors, etc. [Explanation of symbols]

[0055] 1 Heater wire (wire) 3 Core material 5a Conductor wire 5b Insulation coating 9 Heat-sealed part 11 Base material 21 Planar unit 23 Needle thread (sewing thread) 25 Lower thread (sewing thread) 31 Heater wire (wire) 33 Core material 35a Conductor wire 35b Insulation coating 39 Heat-sealed part 71 Steering wheel 77 Wheel core material 78 Covering material 81 Vehicle seats 83 Skin cover 85 Seat Pad

Claims

1. A planar unit comprising a substrate and a linear body disposed on the substrate, the linear body being either a heater wire or a sensor wire, or both, a heat-sealed portion is formed on the outermost layer of the linear body, a sewing thread connecting the linear body and the base material; The planar unit has the sewing thread biting into the heat-sealed portion of the linear body.

2. A surface unit as described in claim 1, wherein the thickness of the base material at the portion where the linear body is arranged is thin to conform to the shape of the linear body, and the sewing thread is inserted into the heat-sealed portion of the linear body, resulting in a generally flat shape.

3. A planar unit comprising a substrate and a linear body disposed on the substrate, the linear body being either a heater wire or a sensor wire, or both, a heat-sealed portion is formed on the outermost layer of the linear body, a sewing thread mark formed by melting a sewing thread connecting the linear body and the base material; A planar unit in which the heat-sealed portion of the linear body and the sewing marks are flattened.

4. The surface unit of claim 3, wherein the thickness of the base material at the location where the linear body is arranged is thin to conform to the shape of the linear body, and the heat-sealed portion of the linear body and the sewing marks are flattened, resulting in a generally flat shape.

5. A steering wheel comprising the planar unit according to any one of claims 1 to 4, a wheel core material, and a covering material, wherein the planar unit is disposed between the wheel core material and the covering material.

6. A method for manufacturing a planar unit, the method comprising the steps of: fixing a linear body having a heat-sealed portion formed on the outermost layer to a base material with a sewing thread; and heating and pressurizing the base material and the linear body to thin the thickness of the portion of the base material where the linear body is arranged to conform to the shape of the linear body, causing the sewing thread to bite into the heat-sealed portion of the linear body to give it a generally flat shape, and fixing the base material and the linear body with the heat-sealed portion, wherein the linear body is either a heater wire or a sensor wire, or both.

7. A method for manufacturing a planar unit, the method comprising the steps of: fixing a linear body having a heat-sealed portion formed on the outermost layer to a base material with a sewing thread; heating and pressurizing the base material and the linear body to thin the thickness of the portion of the base material where the linear body is arranged so as to conform to the shape of the linear body, fusing the sewing thread and the heat-sealed portion, flattening the sewing thread mark formed by the melting of the sewing thread and the heat-sealed portion to form a generally flat shape, and fixing the base material and the linear body with the heat-sealed portion, wherein the linear body is either a heater wire or a sensor wire, or both.

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