Seat heater, seat heater unit, and seat

Abstract

A seat heater 4A comprises a flexible base material 5 and a conductive conductor part 6 that is formed on the base material 5. The base material 5 includes first portions 52a, 52b and second portions 53a, 53b that are connected to the first portions 52a, 52b and are positioned at a position that corresponds to a suspension groove in a sitting surface part. The conductor part 6 includes heat generation parts 63a–63f that are positioned at the first portions 52a, 52b and generate heat by electrical resistance and wide parts 64a, 64b that are positioned at the second portions 53a, 53b, are connected to the heat generation parts 63a–63f, and are wider than the heat generation parts 63a–63f.

Description

Seat heater, seat heater unit, and seat 【0001】 The present invention relates to a seat heater, a seat heater unit, and a seat. In designated countries where incorporation by reference is permitted, the contents described in Japanese Patent Application No. 2024-209744, filed in Japan on December 2, 2024, are incorporated herein by reference and constitute part of this specification. 【0002】 A heater unit is known that consists of a base material and a heater element disposed on the base material (see, for example, Patent Document 1). This heater unit includes a plurality of heating sections and a connecting section that connects the plurality of heating sections, and the cord-shaped heater as the heater element is arranged in the heating sections and the connecting section. 【0003】 When this heater unit is installed in a vehicle seat, the connecting portion of the heater unit is placed in a folded state in the suspension portion of the vehicle seat (see, for example, Patent Document 1 (paragraphs

[0018] ,

[0019] ,

[0025] , Figures 7 and 9)). 【0004】 Japanese Patent Publication No. 2023-15829 【0005】 In the heater unit described in Patent Document 1 above, the cord-type heater in the connecting section generates heat in the same way as the cord-type heater in the heating section. However, since the connecting section is housed in the suspension section and is not close to the occupants, the heat generated by the cord-type heater in the connecting section cannot efficiently warm the occupants. In other words, there is a problem that the electricity consumed to generate heat in the cord-type heater in the connecting section is wasted. 【0006】 The problem that this invention aims to solve is to provide a sheet heater, a sheet heater unit, and a sheet that can improve the efficiency of the power consumed for heat generation. 【0007】[1] One aspect of the present invention is a sheet heater to be attached to a sheet, the sheet heater comprising a flexible base material and a conductive conductor formed on the base material, the base material including a first portion and a second portion connected to the first portion and positioned corresponding to a suspension groove formed on the surface of the sheet, the conductor portion including a heating portion disposed in the first portion and generating heat due to electrical resistance and a wide portion disposed in the second portion, connected to the heating portion and having a width wider than the width of the heating portion. 【0008】 [2] Embodiment 2 of the present invention is a sheet heater according to Embodiment 1, wherein the base material includes a plurality of first parts, and the second part is a sheet heater that connects the plurality of first parts. 【0009】 [3] Embodiment 3 of the present invention is a seat heater according to Embodiment 2, wherein the second portion has a width wider than the width of the first portion. 【0010】 [4] Embodiment 4 of the present invention is a seat heater according to Embodiment 2 or 3, wherein the second portion comprises a connecting portion that connects the plurality of first portions, and a protruding portion that is connected to the connecting portion and protrudes from the connecting portion in the width direction of the connecting portion, and the wide portion comprises a first wide portion disposed on the connecting portion and a second wide portion that is connected to the first wide portion and disposed on the protruding portion. 【0011】 [5] Embodiment 5 of the present invention is a seat heater in which the second portion is bent so that the connecting portion and the protruding portion overlap in a plan view, and the first wide portion and the second wide portion overlap in a plan view. 【0012】 [6] Embodiment 6 of the present invention is a seat heater according to Embodiment 5, wherein the seat heater further comprises a joining member that maintains the second portion in a folded state. 【0013】[7] Embodiment 7 of the present invention is a sheet heater according to Embodiment 6, wherein the sheet heater further comprises a base material holding portion that is attached to the base material and holds the base material, the base material holding portion includes a third portion attached to the connecting portion and a fourth portion attached to the protruding portion, and the joining member is a sheet heater that joins the third portion and the fourth portion with the second portion bent. 【0014】 [8] Embodiment 8 of the present invention is a seat heater according to any of embodiments 1 to 7, wherein the first portion includes a meandering extension. 【0015】 [9] Embodiment 9 of the present invention is a heat sheeter unit comprising a sheet heater according to any of embodiments 1 to 8 and a power supply unit that supplies power to the conductor portion. 【0016】

[10] Embodiment 10 of the present invention comprises a sheet body having a suspension groove formed on its surface and a sheet heater according to any of embodiments 1 to 8, wherein the second portion is a sheet housed in the suspension groove in a curved state. 【0017】 According to the present invention, the base material includes a first portion and a second portion positioned corresponding to the suspension groove, and the conductor portion includes a heat-generating portion positioned in the first portion that generates heat due to electrical resistance, and a wide portion positioned in the second portion that has a width wider than the width of the heat-generating portion. Since the electrical resistance value of the wide portion is smaller than that of the heat-generating portion, the amount of heat generated by the wide portion is smaller than that of the heat-generating portion. In other words, the present invention makes it possible to reduce the amount of heat generated in the portion corresponding to the suspension groove, thereby improving the efficiency of power consumed for heat generation. 【0018】Figure 1 is a plan view showing a sheet in an embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a plan view showing a sheet heater unit in an embodiment of the present invention, and is a plan view showing the sheet heater unit before the second portion is folded. Figure 4 is a plan view showing a sheet heater unit in an embodiment of the present invention, and is a plan view showing the sheet heater unit after the second portion is folded. Figure 5 is a plan view showing a substrate in an embodiment of the present invention. Figure 6 is a cross-sectional view taken along line VI-VI in Figure 1. Figure 7(a) is a cross-sectional view for illustrating the redundancy of the sheet heater in an embodiment of the present invention, and Figure 7(b) is a plan view for illustrating the redundancy of the sheet heater in an embodiment of the present invention. Figure 8 is an enlarged plan view showing a first modified example of the sheet heater in an embodiment of the present invention, and is an enlarged plan view showing the first modified example of the sheet heater before the second portion is folded. Figure 9 is an enlarged plan view showing a first modified example of the sheet heater in an embodiment of the present invention, and is an enlarged plan view showing the first modified example of the sheet heater after the second portion is folded. Figure 10 is a plan view showing a second modified example of the seat heater according to an embodiment of the present invention, and is a plan view showing the seat heater before the second portion is folded. Figure 11 is a plan view showing a second modified example of the seat heater according to an embodiment of the present invention, and is a plan view showing the seat heater after the second portion has been folded. 【0019】 Embodiments of the present invention will be described below with reference to the drawings. 【0020】 Figure 1 is a plan view showing the sheet 1 in this embodiment. Figure 2 is a cross-sectional view along the line II-II in Figure 1. Figure 3 is a plan view showing the sheet heater unit 3A in this embodiment, and is a plan view showing the sheet heater unit 3A before the second portions 53a and 53b are folded. Figure 4 is a plan view showing the sheet heater unit 3A in this embodiment, and is a plan view showing the sheet heater unit 3A after the second portions 53a and 53b have been folded. 【0021】As shown in FIG. 1, the seat 1 in the present embodiment is a seat installed in the passenger compartment of a vehicle, although it is not particularly limited. A passenger of the vehicle sits on this seat 1. In the following embodiments, the seat 1 for a vehicle is exemplified, but this seat 1 may be a seat other than for a vehicle. 【0022】 The seat 1 in the present embodiment includes a seat body 2 and a seat heater 4A. This seat body 2 includes a seating surface portion (cushion pad) 21. The seat body 2 also includes a backrest (not shown), a headrest (not shown), and the like. Further, the seat body 2 also includes a trim cover (not shown) that covers the seat heater 4A. 【0023】 This seating surface portion 21 includes a seating portion 22 on which a passenger sits and a placement portion 23 on which a backrest (not shown) is placed. The seating portion 22 is disposed at a position corresponding to the buttocks and thighs of the passenger and is located in front of the placement portion 23. 【0024】 This seating portion 22 includes a first hanging groove 211 on its upper surface. As shown in FIGS. 1 and 2, the first hanging groove 211 in the present embodiment is a groove that extends along the left - right direction and is recessed downward. Inside this first hanging groove 211, the seating surface portion 22 and the seat heater 4A are fixed to each other by a fixing jig (not shown). The extending direction of the first hanging groove 211 may be a direction other than the left - right direction. 【0025】 More specifically, the seat heater 4A is valley - folded along the straight line L １ , L ２ as shown in FIG. 3, whereby, as shown in FIG. 4, a pair of overlapping portions 4a, 4b are formed on the seat heater 4A. As shown in FIG. 2, these overlapping portions 4a, 4b are accommodated in the first hanging groove 211 in a state of being curved downward. Then, the overlapping portions 4a, 4b are fixed to the seating portion 22 by the above - mentioned fixing jig (not shown). 【0026】As shown in Figure 1, the mounting section 23 is not positioned to correspond to the occupant, but rather to the backrest (not shown). The mounting section 23 includes a second suspension groove 212 on its upper surface. This second suspension groove 212, like the first suspension groove 212, extends along the left-right direction and is recessed downwards. Within this second suspension groove 212, the mounting section 23 and the seat heater 4A are fixed to each other by a fixing jig (not shown). Note that the direction of extension of the second suspension groove 212 may be in a direction other than the left-right direction. 【0027】 The rear portion 51 (described later) of the base material 5 of the sheet heater 4A, the first external connection portion 61 (described later) of the conductor portion 6, and the second external connection portion 62 (described later) of the conductor portion 6 are housed in a downwardly curved state in the second suspension groove 212. These portions are then fixed to the mounting portion 23 by a fixing jig (not shown). 【0028】 As shown in Figure 3, the seat heater unit 3A comprises a power supply unit 100 and the aforementioned seat heater 4A. The power supply unit 100 in this embodiment is not particularly limited, but is located outside the seat 1. The power supply unit 100 supplies power to the seat heater 4A, thereby causing the seat heater 4A to generate heat. The power supply unit 100 is not particularly limited, but includes a power source (not shown), such as an auxiliary battery, and a control circuit (not shown) that controls the power supplied from the auxiliary battery to be appropriate for the operation of the seat heater 4A. 【0029】 The sheet heater 4A comprises a base material 5, a conductor portion 6, a base material holding portion 7, and a pair of joining members 8. The base material 5 is a resin film having flexibility and electrical insulation properties. Examples of resin materials constituting this resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), liquid crystal polymer (LCP), polyetherimide (PEI), polyetheretherketone (PEEK), and aramid. 【0030】Figure 5 is a plan view showing the base material 5 in this embodiment. As shown in Figure 5, the base material 5 comprises a rear portion 51, a plurality (two in this example) of first portions 52a, 52b, and a plurality (two in this example) of second portions 53a, 53b. A base material 5 of this shape can be manufactured, for example, by punching out a resin sheet. 【0031】 The rear portion 51 constitutes the rear of the base material 5. In this embodiment, the rear portion 51 is not particularly limited, but is located below the backrest (not shown). That is, the rear portion 51 is positioned on the mounting portion 23 of the seat body 2. This rear portion 51 has a substantially rectangular outer shape. This rear portion 51 includes a left portion 511 and a right portion 512. The left portion 511 is located on the left side of the vehicle, while the right portion 512 is located on the right side of the vehicle. 【0032】 The first portion 52a is positioned on the seating portion 22 of the seat body 2. This first portion 52a is located in front of the rear portion 51 and is connected to the rear portion 51. The first portion 52a includes a plurality (four in this example) of first extensions 521a, 521b, 521c, and 521d. The first extensions 521a to 521d are spaced apart from each other and arranged along the left-right direction in the figure. 【0033】 The first extending portions 521a and 521b are interposed between the left side portion 511 and the second portion 53a. The first extending portions 521a and 521b extend along the longitudinal direction of the vehicle, while repeatedly meandering in the lateral direction of the vehicle. 【0034】 Furthermore, the first extended portions 521c and 521d are interposed between the right side portion 512 and the second portion 53b. The first extended portions 521c and 521d extend along the longitudinal direction of the vehicle, repeatedly meandering in the left-right direction of the vehicle. In this embodiment, the first extended portion 521c has a shape symmetrical to the first extended portion 521b. Similarly, the first extended portion 521d has a shape symmetrical to the first extended portion 521a. 【0035】As described above, the first extended portions 521a to 521d are arranged in the left-right direction in the figure with a gap between them, so that the first extended portions 521a to 521d can easily expand and contract along the left-right direction of the vehicle. Therefore, when a load is applied to the seat heater 4A by an occupant or the like, the first portion 52a can expand and contract in the left-right direction, thus suppressing the occurrence of tearing of the first portion 52a due to the load. 【0036】 Furthermore, because the first extended portions 521a to 521d have a meandering shape that repeatedly meanders in the left-right direction of the vehicle, the first extended portions 521a to 521d are more likely to expand and contract along the front-rear direction of the vehicle. Therefore, when a load is applied to the seat heater 4A by an occupant or the like, the first portion 52a expands and contracts in the front-rear direction, thereby suppressing the occurrence of tearing of the first portion 52a. 【0037】 The second portion 53a has a rectangular planar shape and is wider than the width of the first portions 52a and 52b. The second portion 53a is also positioned on the seating portion 22 of the seat body 2. This second portion 53a is located in front of the first extensions 521a and 521b and is connected to the first extensions 521a and 521b. Furthermore, the second portion 53a is located behind the second extensions 522a and 522b of the first portion 52b and is connected to the left end of the second extensions 522a and 522b. In this way, the second portion 53a interposes itself between the first extensions 521a and 521b and the second extensions 522a and 522b, thereby connecting the first extensions 521a and 521b and the second extensions 522a and 522b. 【0038】 This second portion 53a includes a connecting portion 531a and a protruding portion 532a. The connecting portion 531a is directly connected to the first extending portions 521a, 521b and the second extending portions 522a, 522b. 【0039】A projection 532a extends from this connecting portion 531a toward the right of the vehicle. The projection 532a is not particularly limited, but it is not directly connected to the first extensions 521a, 521b and the second extensions 522a, 522b. As will be described in detail later, the second portion 53a is a straight line L １ By being bent, the protruding portion 532a is positioned above the connecting portion 531a. １ This is a hypothetical straight line extending along the boundary between the connecting portion 531a and the protruding portion 532a. 【0040】 The second portion 53b has a rectangular planar shape that is symmetrical to the second portion 53b, and has a width greater than the width of the first portions 52c and 52d. The second portion 53b is also positioned on the seating portion 22 of the seat body 2. This second portion 53b is located in front of the first extensions 521c and 521d and is connected to the first extensions 521c and 521d. The second portion 53a is located behind the second extensions 522a and 522b of the first portion 52b and is connected to the right end of the second extensions 522a and 522b. In this way, the second portion 53b is interposed between the first extended portions 521a, 521b and the second extended portions 522a, 522b, thereby connecting the first extended portions 521a, 521b and the second extended portions 522a, 522b. 【0041】 This second portion 53b includes a connecting portion 531b and a protruding portion 532b. The connecting portion 531b is located in front of the first extending portions 521c, 521d and is directly connected to the first extending portions 521c, 521d and the second extending portions 522a, 522b. 【0042】 A projection 532b extends from this connecting portion 531b toward the left of the vehicle. This projection 532b is not particularly limited, but is not directly connected to the first extending portions 521a, 521b and the second extending portions 522a, 522b. Furthermore, as will be described in detail later, the second portion 53b is a straight line L ２ By being bent, the protruding portion 532b is positioned above the connecting portion 531b. ２This is a hypothetical straight line extending along the boundary between the connecting portion 531b and the protruding portion 532b. 【0043】 The first portion 52b is connected to the second portions 53a and 53b. The first portion 52b is also positioned on the seating portion 22 of the seat body 2. The first portion 52b includes a plurality (two in this example) of second extensions 522a and 522b. The second extensions 522a and 522b are spaced apart from each other, and the second extension 522b is positioned inside the second extension 522a. 【0044】 The second extension 522a extends in a roughly U-shape, meandering repeatedly. The left end of this second extension 522a is connected to the second portion 53a, and the right end of the second extension 522a is connected to the second portion 53b. 【0045】 A second extending portion 522b is positioned inside the second extending portion 522a. The second extending portion 522b, like the second extending portion 522a, extends in a roughly U-shape while repeatedly meandering. The left end of the second extending portion 522a is connected to the second portion 53a, and the right end of the second extending portion 522a is connected to the second portion 53b. The second extending portion 522a extends in a roughly U-shape while repeatedly meandering. 【0046】 As shown in Figure 3, a conductive portion 6 is formed on the upper surface of the substrate 5. The material constituting the conductive portion 6 in this embodiment is not particularly limited, but metals can be exemplified. Examples of such metals, though not particularly limited, include aluminum, copper, copper alloys, silver, silver alloys, or stainless steel. 【0047】 Such a conductive portion 6 is not particularly limited, but for example, it can be formed by patterning the aluminum foil of an aluminum foil / PET composite film by etching or the like. This aluminum foil / PET composite film is a composite material in which aluminum foil is bonded to a polyester film via an adhesive layer. Specific examples of such aluminum foil / PET composite films are not particularly limited, but Alpet (registered trademark) manufactured by Panac Co., Ltd. can be cited. 【0048】Alternatively, the conductive portion 6 may be formed by printing a conductive paste onto the substrate 5 and allowing it to solidify (harden), although this is not particularly limited. Examples of methods for printing the conductive paste include screen printing, gravure offset printing, flexographic printing, and inkjet printing. The conductive paste is composed of conductive particles and a binder resin mixed with water or a solvent and various additives. 【0049】 Specific examples of conductive particles include silver, copper, nickel, tin, bismuth, zinc, indium, palladium, and their alloys, metal salts, carbon, conductive polymers such as PEDOT / PSS, etc. Specific examples of binder resins include acrylic resin, polyester resin, epoxy resin, vinyl resin, urethane resin, phenolic resin, polyimide resin, silicone resin, fluororesin, etc. Furthermore, examples of solvents included in the conductive paste include α-terpineol, butyl carbitol acetate, butyl carbitol, 1-decanol, butyl cellsolve, diethylene glycol monoethyl ether acetate, tetradecane, etc. The binder resin may be omitted from the above conductive paste. Alternatively, conductive ink may be used instead of the above conductive paste. 【0050】 As shown in Figure 3, the conductor portion 6 includes a first external connection portion 61, a second external connection portion 62, a plurality of (six in this example) heat-generating portions 63a to 63f, and a plurality of (two in this example) wide portions 64a and 64b. 【0051】The first external connection portion 61 is formed on the left side portion 511 of the rear portion 51 of the base material 5. This first external connection portion 61 is electrically connected to the power supply unit 100. On the other hand, the second external connection portion 62 is formed on the right side portion 512 and is spaced apart from the first external connection portion 61. This second external connection portion 62 is also electrically connected to the power supply unit 100. The first and second external connection portions 61 and 62 have a width greater than the width of the heat-generating portions 63a to 63f, which will be described later, and have a low resistance value, so they generate almost no heat. Thus, the first and second external connection portions 61 and 62 are parts used for electrical connection with the power supply unit 100 and generate almost no heat, so they are positioned in a location corresponding to the mounting portion 23. 【0052】 The first and second external connection parts 61 and 62 are not particularly limited, but are composed of a solid pattern (planar pattern). In this embodiment, the first external connection part 61 is connected to the positive terminal of the power supply unit 100 and the second external connection part 62 is connected to the negative terminal of the power supply unit 100, but this relationship may be reversed. 【0053】 Figure 6 is a cross-sectional view along the line VI-VI in Figure 1. As shown in Figures 3 and 6, the heating elements 63a to 63e are each thin lines formed on the first parts 52a and 52b. The width of the heating elements 63a to 63e is set to be thinner than that of the wider parts 64a and 64b, so the resistance of heating element 63a is high. For this reason, heating elements 63a to 63e generate heat resistively due to the current supplied by the power supply unit 100. Since heating elements 63a to 63e are the parts that generate heat to warm the occupants, they are positioned in a location corresponding to the seating area 22. 【0054】The heating elements 63a and 63b are interposed between the first external connection element 61 and the wide element 64a. The heating elements 63a and 63b are formed on the first extended elements 521a and 521b, respectively. Although not particularly limited, the heating elements 63a and 63b are densely packed together by being curved multiple times on the first extended elements 521a and 521b. More specifically, the heating elements 63a and 63b include a plurality of first fine wires extending along the meandering direction of the first extended elements 521a and 521b, and arc-shaped second fine wires connecting the plurality of first fine wires. 【0055】 The heating element 63c is a thin wire formed on the first extended portion 521c. This heating element 63c has a shape that is symmetrical with respect to the heating element 63b. Similarly, the heating element 63d is a thin wire formed on the first extended portion 521d of the first portion 52a. This heating element 63d has a shape that is symmetrical with respect to the heating element 63a. 【0056】 The heat-generating portion 63e is formed on the second extension portion 522a of the first portion 52b. The heat-generating portion 63e extends in a generally U-shape, following the planar shape of the second extension portion 522a. This heat-generating portion 63e is also densely packed due to being curved multiple times on the second extension portion 522a. 【0057】 The heat-generating portion 63f is formed on the second extension portion 522b of the first portion 52b and is located inside the heat-generating portion 63e. The heat-generating portion 63f extends in a roughly U-shape overall, following the planar shape of the second extension portion 522b. This heat-generating portion 63f is also densely packed due to being curved multiple times on the second extension portion 522b. 【0058】The wide portion 64a is formed on the second portion 53a. The wide portion 64a is interposed between the heating portion 63a and heating portion 63e, and also between the heating portion 63b and heating portion 63f. Therefore, the wide portion 64a is positioned in a location corresponding to the seat portion 22. This wide portion 64a is composed of a substantially rectangular solid pattern (surface pattern) having a width wider than the width of the heating portions 63a to 63f. Therefore, the electrical resistance value of the wide portion 64a is lower than the electrical resistance value of the heating portions 63a to 63e. Also, when the power supply unit 100 supplies current to the conductor portion 6, the wide portion 64a hardly generates any heat. This wide portion 64a is a connecting portion that allows the current supplied from the heating portions 63a and 63b to flow to the heating portions 63e and 63f. 【0059】 The wide portion 64a includes a first wide portion 641a and a second wide portion 642a. The first wide portion 641a is formed on the connecting portion 531a of the second portion 53a. The first wide portion 641a is directly connected to the heating portions 63a, 63b and the left ends of the heating portions 63e, 63f. 【0060】 The second wide portion 642a is formed on the protruding portion 532a of the second portion 53a and protrudes from the first wide portion 641a toward the right of the vehicle. This second wide portion 642a is not directly connected to the heating portions 63a, 63b and the heating portions 63e, 63f. 【0061】 This wide portion 64a, together with the second portion 53a of the base material 5 and the base material holding portion 7, forms a straight line L １ It is then folded in a valley fold. At this time, as shown in Figure 2, the first wide portion 641a and the second wide portion 642a are joined via the joining member 8, and an overlapping portion 4a is formed. As shown in Figures 1 and 2, this overlapping portion 4a is a part that is curved downward and accommodated in the suspension groove 211. By forming such an overlapping portion 4a, the sheet heater 4A can be made redundant, as will be explained below with reference to Figure 7. 【0062】FIG. 7(a) is a cross-sectional view for explaining the redundancy of the seat heater 4A in the present embodiment. FIG. 7(a) shows a state in which a load F is applied to the vicinity of the hanging groove 211. In FIG. 7(a), for convenience of explanation, the illustration of the base material holding portion 7 is omitted. FIG. 7(b) is a plan view for explaining the redundancy of the seat heater 4A in the present embodiment. FIG. 7(b) shows a state in which the overlapping portion 4a of the seat heater 4A is unfolded to explain the path F of the current flowing through the wide portion 64a. Ｉ To explain, it shows a state in which the overlapping portion 4a of the seat heater 4A is unfolded. 【0063】 As shown in FIG. 7(a), when a load F is applied to the vicinity of the hanging groove 211, the inner wall of the hanging groove 211 inclines inward, and the internal space of the hanging groove 211 is compressed. Along with this, the amount of deflection at the four curved portions BP １ , BP ２ , BP ３ , BP ４ in the overlapping portion 4a increases, and the bending stress at the curved portions BP １ , BP ２ , BP ３ , BP ４ increases. Therefore, breakage is likely to occur in the wide portion 64a at the curved portions BP １ , BP ２ , BP ３ , BP ４ . 【0064】 However, in the overlapping portion 4a in the present embodiment, by being affected by the thickness of each member constituting the overlapping portion 4a, the radius of curvature of the first wide portion 641a and the radius of curvature of the second wide portion 642a can be made different from each other at the curved portions BP １ , BP ２ , BP ３ , BP ４ . For example, at the curved portion BP １ , the radius of curvature of the second wide portion 642a is larger than the radius of curvature of the first wide portion 641a. That is, at the curved portion BP １In this case, the second wide portion 642a is curved more gently than the first wide portion 641a, and the bending stress generated in the second wide portion 642a is smaller than the bending stress generated in the first wide portion 641a. Therefore, the curved portion BP １ In this configuration, the second wide portion 642a is less prone to breakage than the first wide portion 641a. 【0065】 Furthermore, the curved section BP in this example ２ , BP ３ Therefore, the radius of curvature of the first wide section 641a is larger than the radius of curvature of the second wide section 642a. Thus, the curved section BP ２ , BP ３ In this example, the first wide portion 641a is less likely to break than the second wide portion 642a. ４ Now, the curved section BP １ Similarly, the radius of curvature of the second wide portion 642a is larger than the radius of curvature of the first wide portion 641a. Therefore, the curved portion BP ４ In this configuration, the second wide portion 642a is less prone to breakage than the first wide portion 641a. 【0066】 Thus, each curved section BP １ ~BP ４ In this case, because the wide portion 64a has a mixture of portions with different radii of curvature, even if cracks occur in the portions with smaller radii of curvature, the portions with larger radii of curvature can function as bypasses, thereby suppressing electrical disconnection in the wide portion 64a. For example, in this example, as shown in Figure 7(b), the curved portion BP １ , BP ４ In this case, even if a crack occurs in the first wide section 641a with a small radius of curvature, the second wide section 642a with a large radius of curvature functions as a bypass. Similarly, the curved section BP ２ , BP ３ In this case, even if a crack occurs in the second wide section 642a with a small radius of curvature, the first wide section 641a with a large radius of curvature functions as a bypass. Therefore, in the wide section 64a, the current path F passes through the portion with a large radius of curvature. ＩThis ensures redundancy for the seat heater 4A. 【0067】 As shown in Figure 3, the wide portion 64b is formed on the second portion 53b. The wide portion 64b is interposed between the heating portions 63c and 63d and the right ends of the heating portions 63e and 63f. For this reason, the wide portion 64a is positioned in a location corresponding to the seating portion 22. This wide portion 64b has a planar shape that is symmetrical to the wide portion 64a. The resistance of the wide portion 64b is also low, similar to the wide portion 64a, and the wide portion 64b hardly generates any heat when the power supply unit 100 supplies current to the conductor portion 6. This wide portion 64b is a connecting portion that allows the current supplied from the heating portions 63e and 63f to flow to the heating portions 63c and 63d. 【0068】 The wide portion 64b includes a first wide portion 641b and a second wide portion 642b. The first wide portion 641b is formed on the connecting portion 531b of the second portion 53b. The first wide portion 641b is directly connected to the heating portions 63c, 63d and the right ends of the heating portions 63e, 63f. 【0069】 The second wide portion 642b is formed on the protruding portion 532b of the second portion 53b and protrudes from the first wide portion 641b toward the left of the vehicle. This second wide portion 642b is not directly connected to the heating portions 63c, 63d and 63e, 63f. 【0070】 This wide portion 64b, like the wide portion 64a, is a straight line L ２ The sheet is folded in a valley fold, forming an overlapping section 4b as shown in Figure 4. As shown in Figure 1, the overlapping section 4b is also fixed to the suspension groove 211 in a state that is curved downwards. Since this wide section 64b has basically the same structure as the wide section 64a described above, the overlapping section 4b can have a mix of sections with a large radius of curvature and sections with a small radius of curvature, thereby ensuring redundancy for the sheet heater 4A. 【0071】The base material holding portion 7 is provided on the lower surface of the base material 5. The base material 5 is not particularly limited, but is attached to the base material holding portion 7 by an adhesive (not shown) or the like, and the base material holding portion 7 holds the base material 5. Examples of the base material holding portion 7 include nonwoven fabric and thin sheets of foamed resin. Examples of nonwoven fabrics include polyester and felt, and examples of thin sheets of foamed resin include thin sheets of foamed urethane foam. In particular, thin sheets of foamed resin are flexible, which can improve the flexibility of the sheet heater 4A. 【0072】 This base material holding portion 7 includes a third portion 71 attached to the connecting portions 531a and 531b of the base material 5, and a fourth portion 72 attached to the protruding portions 532a and 532b. The third and fourth portions 71 and 72 constitute a part of the overlapping portions 4a and 4b described above. 【0073】 In this embodiment, the joining member 8 (see Figure 2) joins the first wide portion 641a and the second wide portion 642a at the overlapping portion 4a, and joins the first wide portion 641b and the second wide portion 642b at the overlapping portion 4b. The joining member 8 is not particularly limited, but examples include adhesives such as double-sided tape, adhesives, or hot melts. 【0074】 In this embodiment, the wide portions 64a and 64b of the conductor portion 6 are housed in the suspension groove 211 and are not in close proximity to the occupants. On the other hand, the heat-generating portions 63a to 63f of the conductor portion are located in areas other than the suspension groove 211 and are in close proximity to the occupants. Therefore, it is possible to suppress the heat generation of the wide portions 64a and 64b in the suspension groove 211, which do not contribute much to heating the occupants, while generating heat in the heat-generating portions 63a to 63f in areas other than the suspension groove 211, which do contribute to heating the occupants. Accordingly, this embodiment makes it possible to improve the efficiency of the power consumed for heat generation. 【0075】The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. 【0076】 For example, in the above embodiment, the first wide portion 641a and the second wide portion 642a are joined by the joining member 8, and the first wide portion 641b and the second wide portion 642b are joined at the overlapping portion 4b, but the embodiment is not limited to this. As in the first modified example described below, the base material holding portions 7 may be joined together. 【0077】 Figure 8 is an enlarged plan view showing a first modified example of the seat heater 4A in this embodiment, and is an enlarged plan view showing a first modified example of the seat heater 4B before the second portions 53a and 53b are folded. Figure 9 is an enlarged plan view showing a first modified example of the seat heater 4A in this embodiment, and is an enlarged plan view showing a first modified example of the seat heater 4B after the second portions 53a and 53b have been folded. 【0078】 As shown in Figure 8, in the modified seat heater 4B, the second portion 53a of the base material 5 includes a first notch 533a and a second notch 534a. The first notch 533a is formed at the left end of the connecting portion 531a and is recessed toward the right side of the vehicle. On the other hand, the second notch 534a is formed at the right end of the protruding portion 532a and is recessed toward the left side of the vehicle. 【0079】 The wide portion 64a of the conductor portion 6 includes a third notch 643a and a fourth notch 644a. The third notch 643a overlaps with the first notch 533a in a plan view. This third notch 643a is formed at the left end of the first wide portion 641a and is recessed toward the right side of the vehicle. 【0080】In this modified example, a portion of the third portion 71 of the base material holding portion 7 is exposed through the first notch 533a and the third notch 643a. On the other hand, inside the second notch 534 and the fourth notch 644a, a portion of the third portion 72 is exposed from the protruding portion 532a and the second wide portion 642a, and the joining member 8 is provided on this exposed portion of the third portion 72. 【0081】 As shown in Figure 9, the seat heater 4B is aligned in a straight line L １ When folded along the valley fold, the third portion 71 and the fourth portion 72 of the base material holding portion 7 are joined by the joining member 8 at the overlapping portion 4a. This makes the thickness of the overlapping portion 4a in this modified example thinner than the thickness of the overlapping portion 4a when the joining member 8 is placed between the first wide portion 641a and the second wide portion 642a. Therefore, the increase in bending stress due to the increase in the thickness of the overlapping portion 4a can be suppressed, and thus the fracture of the wide portion 64a can be suppressed. 【0082】 As shown in Figure 8, the second portion 53b in this modified example has a planar shape symmetrical to the second portion 53a and includes a first notch 533b and a second notch 534b. Similarly, the wide portion 64b has a planar shape symmetrical to the wide portion 64a and includes a third notch 643b and a fourth notch 644b. 【0083】 Therefore, as shown in Figure 9, in the overlapping portion 4b, similar to the overlapping portion 4a, the increase in the thickness of the overlapping portion 4b can be suppressed. Thus, the fracture of the wide portion 64b can be suppressed. 【0084】In this modified example, the base material holding portion 7 is exposed by a notch, but this is not the only way to do so. Instead of a notch, an opening or the like may be used to expose the base material holding portion 7. Also, in this modified example, the base material holding portions 7 are joined together by the bonding or adhesive of the joining member 8, but this is not the only way to do so. For example, the base material holding portions 7 may be sewn together with thread. Alternatively, if the base material holding portions 7 are made of a material that melts when heated, the base material holding portions 7 may be heat-welded together. Furthermore, in the overlapping portions 4a and 4b, the joining member 8 may be omitted, and the first wide portions 641a and 641b and the second wide portions 642a and 642b may not be joined together. 【0085】 Furthermore, in the above embodiment, one wide portion 64a is provided in the second portion 53a and one wide portion 64b is provided in the second portion 53b, but the embodiment is not limited to this. As shown in the second modified example described below, multiple wide portions may be provided in each of the second portions 53a and 53b. 【0086】 Figure 10 is a plan view showing a second modified example of the seat heater 4A in this embodiment, and is a plan view showing the seat heater 4C before the second portions 53c and 53d are folded. Figure 11 is a plan view showing a second modified example of the seat heater 4A in this embodiment, and is a plan view showing the seat heater 4C after the second portions 53c and 53d have been folded. 【0087】 The second portion 53c of the seat heater 4C shown in the second modified example includes a pair of protrusions 532c and 535c that project from the connecting portion 531c to the left and right. Similarly, the second portion 53d also includes a pair of protrusions 532d and 535d that project from the connecting portion 531d to the left and right. 【0088】A pair of widely spaced wide sections 64c and 64d are formed on the second section 53c. The wide section 64c includes a first wide section 641c and a second wide section 642c. The first wide section 641c is formed on the connecting section 531c and is directly connected to the heating sections 63a and 63e. The second wide section 642c protrudes from the first wide section 641c toward the left of the vehicle, and this second wide section 642c is formed on the protruding section 535c. 【0089】 The wide section 64d is provided to the right of the wide section 64c. This wide section 64d includes a first wide section 641d and a second wide section 642d. The first wide section 641d is formed on the connecting section 531c so as to be separated from the first wide section 641c and is directly connected to the heating sections 63b and 63f. The second wide section 642d protrudes from this first wide section 641d toward the right of the vehicle, and this second wide section 642d is formed on the protruding section 532c. 【0090】 A pair of widely spaced wide sections 64e and 64f are also formed on the second section 53d. The wide section 64e has substantially the same shape as the wide section 64c described above. This wide section 64e includes a first wide section 641e and a second wide section 642e. The first wide section 641e is formed on the connecting section 531d and is directly connected to the heating sections 63c and 63f. The second wide section 642e protrudes from this first wide section 641e toward the left of the vehicle, and this second wide section 642e is formed on the protruding section 532d. 【0091】 The wide section 64f is provided to the right of the wide section 64e. This wide section 64f includes a first wide section 641f and a second wide section 642f. The first wide section 641f is formed on the connecting section 531d so as to be separated from the first wide section 641e and is directly connected to the heating sections 63d and 63e. The second wide section 642f protrudes from this first wide section 641f toward the right of the vehicle, and this second wide section 642f is formed on the protruding section 535d. 【0092】As shown in Figure 11, the sheet heater 4C in this modified example is a straight line L １ ~L ４ It is folded along the valley fold, thereby forming four overlapping sections 4c to 4d. These overlapping sections 4c to 4d are then housed in the suspension grooves 211 (see Figure 2) of the seat surface 21. 【0093】 Furthermore, although the conductive portion 6 is exposed in the above embodiment, the conductive portion 6 may be covered with a protective layer made of a resist material or the like. 【0094】 Furthermore, the bending radius may be reduced by attaching a protective member to one or both sides of the overlapping portions 4a and 4b in the above embodiment. Examples of this protective member include foam material, elastomer, or nonwoven fabric. The protective member may also be placed between the first wide portions 641a and 641b and the second wide portions 642a and 642b in the overlapping portions 4a and 4b. 【0095】 Furthermore, although the above embodiment illustrates the case in which the seat heaters 4A to 4C are attached to the seat portion 21, the invention is not limited to this. The seat heaters 4A to 4C may also be attached to a backrest (not shown), in which case a suspension groove is formed in the backrest, and the overlapping portions 4a to 4d of the seat heaters 4A to 4C are housed and fixed in the suspension groove. 【0096】1...Seat 2...Seat body 21...Seat surface (cushion pad) 22...Seating area 211...First suspension groove 23...Mounting area 3A...Seat heater unit 4A-4C...Seat heater 4a-4f...Overlapping area 5...Base material 51...Rear part 511...Left side part 512...Right side part 52a-52f...First part 521a-521d...First extension part 522a, 522b...Second extension part 53a-53d...Second part 531a, 531b...Connecting part 532a-532d, 535c, 535d...Protruding part 533a, 533b...First notch part 534a, 534b...Second notch part 6...Conductor part 61...First external connection part 62...Second external connection part 63a-63f...Heating part 64a-64f...Wide part 641a, 641b...First wide part 642a, 642b...Second wide part 643a, 643b...Third notch part 644a, 644b...Fourth notch part 7...Base material holding part 71...Third part 72...Fourth part 8...Joining member 100...Power supply part

Claims

1. A sheet heater that can be attached to a sheet, the sheet heater comprising: a flexible base material; and a conductive portion formed on the base material, wherein the base material includes a first portion and a second portion connected to the first portion and positioned to correspond to a suspension groove formed on the surface of the sheet, and the conductive portion includes a heating portion located on the first portion that generates heat due to electrical resistance, and a wide portion located on the second portion that is connected to the heating portion and has a width wider than the width of the heating portion.

2. A sheet heater according to claim 1, wherein the base material includes a plurality of first parts, and the second part connects the plurality of first parts.

3. A seat heater according to claim 2, wherein the second portion has a width wider than the width of the first portion.

4. A seat heater according to claim 2 or 3, wherein the second portion comprises a connecting portion connecting the plurality of first portions, and a protruding portion connected to the connecting portion and projecting from the connecting portion in the width direction of the connecting portion, and the wide portion comprises a first wide portion disposed on the connecting portion and a second wide portion connected to the first wide portion and disposed on the protruding portion.

5. A seat heater according to claim 4, wherein the second portion is bent so that the connecting portion and the protruding portion overlap in a plan view, and the first wide portion and the second wide portion overlap in a plan view.

6. A seat heater according to claim 5, wherein the seat heater further comprises a joining member that maintains the second portion in a folded state.

7. A sheet heater according to claim 6, wherein the sheet heater further comprises a base material holding portion that is attached to the base material and holds the base material, the base material holding portion includes a third portion attached to the connecting portion and a fourth portion attached to the protruding portion, and the joining member joins the third portion and the fourth portion with the second portion bent.

8. A seat heater according to any one of claims 1 to 7, wherein the first portion includes a meandering extension.

9. A seat heater unit comprising a seat heater according to any one of claims 1 to 8, and a power supply unit for supplying power to the conductor portion.

10. A sheet comprising a sheet body having a suspension groove formed on its surface, and a sheet heater according to any one of claims 1 to 8, wherein the second portion of the sheet is housed in the suspension groove in a curved state.

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