Planar heating element

Abstract

To provide a planar heating element that can be easily installed on structures. [Solution] The planar heating element 10 comprises a first electric wire 21, a second electric wire 22 which is arranged such that at least a portion of it runs along the first electric wire 21, a plurality of heating elements 23 connected to the first electric wire 21 and the second electric wire 22, and a planar sheet 40 on which the first electric wire 21, the second electric wire 22, and the plurality of heating elements 23 are arranged. The first electric wire 21 in the sheet 40 includes a first portion 21C extending in a first direction X and a second portion 21D extending in a second direction Y different from the first direction X.

Description

Technical Field

[0005] ,

[0001] The present disclosure relates to a planar heating element.

Background Art

[0002] Linear heaters installed on structures are known for purposes such as snow melting. The linear heater of Patent Document 1 has two electric wires and a heating element provided between the two electric wires. The linear heater of Patent Document 1 heats a structure, for example, by being wound around a columnar structure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the linear heater of Patent Document 1 is used for a structure having a planar portion, in order to efficiently align the linear heater along the surface to be heated, when a plurality of linear heaters are arranged side by side on the surface, it is necessary to connect each linear heater. For this reason, the number of parts increases and the installation work becomes complicated. Also, a single linear heater may be bent at multiple locations. When bending the linear heater, the more abrupt the bending angle, the more likely it is that torsion occurs in the bent portion, reducing the contact area with the portion to be heated and thus possibly deteriorating the heat efficiency. Therefore, a temporary fixing operation using an aluminum tape or the like is required, making the installation work of the linear heater complicated.

Means for Solving the Problems

[0005] (1) A planar heating element that solves the above problems is a planar heating element comprising: a first electric wire; a second electric wire, at least a portion of which is arranged along the first electric wire; a plurality of heating elements connected to the first electric wire and the second electric wire, respectively; and a planar sheet on which the first electric wire, the second electric wire, and the plurality of heating elements are arranged, wherein the first electric wire includes a first portion extending in a first direction and a second portion extending in a second direction different from the first direction in the sheet. With this configuration, in the planar sheet, the first electric wire to which the heating elements are connected extends in both the first and second directions, so that the area that can be heated by the planar heating element can be increased. Therefore, by installing the planar heating element on a structure, the planar portion of the structure can be suitably heated, and the installation work of the planar heating element can be simplified.

[0006] (2) In the planar heating element described in (1) above, two adjacent heating elements are arranged at a predetermined distance apart, and the predetermined distance in the part corresponding to the first part is different from the predetermined distance in the part corresponding to the second part. With this configuration, heating elements can be installed at different predetermined distances in the first part and the second part.

[0007] (3) In the planar heating element of (1) or (2) above, the second direction includes the curvature direction, and the length of the first wire in the second portion is substantially equal to the length of the second wire corresponding to the second portion. With this configuration, the difference between the length of the first wire and the length of the second wire can be reduced.

[0008] (4) In any one of the planar heating elements described in (1) to (3) above, the sheet includes an insulating portion. With this configuration, the first wire, the second wire, and the multiple heating elements can be insulated by the sheet.

[0009] (5) In the planar heating element described in (4) above, the sheet further includes a heat transfer section disposed between the insulating section and the plurality of heating elements. With this configuration, the heat generated by the heating elements can be suitably transferred by the heat transfer section.

[0010] (6) In the planar heating element described in (5) above, a grounding wire is connected to the heat transfer section. With this configuration, the heat transfer section can be grounded by the grounding wire connected to it, so the planar heating element can be used suitably.

[0011] (7) In any one of the planar heating elements described in (1) to (6) above, an insulating protective portion is further provided between the sheet and the first wire, the second wire, and the plurality of heating elements. With this configuration, the protective portion can insulate the sheet from the first wire, the second wire, and the plurality of heating elements.

[0012] (8) In any one of the planar heating elements described in (1) to (7) above, the sheet includes a first sheet and a second sheet positioned on the opposite side of the first sheet, sandwiching the first wire, the second wire, and the plurality of heating elements. With this configuration, the first wire, the second wire, and the plurality of heating elements are sandwiched between the first sheet and the second sheet, thus providing suitable protection for the first wire, the second wire, and the plurality of heating elements.

[0013] (9) The planar heating element described in (8) above is configured to be able to dissipate heat from both the first sheet and the second sheet. With this configuration, both the outer surface of the first sheet and the outer surface of the second sheet can be used as heat dissipation surfaces.

[0014] (10) In the planar heating element described in (8) or (9) above, both ends of the first wire and the second wire are exposed from the portion sandwiched between the first sheet and the second sheet. With this configuration, both ends of the first wire and the second wire can be easily connected to a power source or another planar heating element.

[0015] (11) In any one of the planar heating elements described in (1) to (10) above, the sheet is flexible. With this configuration, the planar heating element can be deformed to conform to the shape of the structure, so that the planar heating element can make suitable contact with the structure. [Effects of the Invention]

[0016] The planar heating element of the present disclosure can simplify the installation work on a structure.

Brief Description of the Drawings

[0017] [Figure 1] It is a plan view of the planar heating element of the embodiment. [Figure 2] It is a cross-sectional view taken along line D2-D2 of FIG. 1. [Figure 3] It is a perspective view showing a part of the heating main body with the covering part of FIG. 1 removed. [Figure 4] It is a perspective view showing a part of the heating main body of FIG. 1. [Figure 5] It is a plan view showing a part of the heating main body with the covering part of FIG. 1 removed. [Figure 6] It is a cross-sectional view of the planar heating element of the first modification example. [Figure 7] It is a cross-sectional view of the planar heating element of the second modification example. [Figure 8] It is a plan view of a part of the heating main body with the covering part of the third modification example removed. [Figure 9] It is a cross-sectional view of the planar heating element of the fourth modification example.

Mode for Carrying Out the Invention

[0018] <Embodiment> Referring to FIGS. 1 to 5, the planar heating element 10 will be described. The planar heating element 10 is used, for example, for snow melting. The planar heating element 10 may be used for other purposes than snow melting. The planar heating element 10 of the present embodiment is attached to a structure having a planar portion, for example.

[0019] <Planar heating element>[[ID= / / 49]] As shown in Figures 1 and 2, the planar heating element 10 is formed in the shape of a plate. The planar heating element 10 is preferably flexible. The planar heating element 10 comprises a heating body portion 20 that generates heat and a planar sheet 40 on which the heating body portion 20 is arranged. The sheet 40 has a rectangular shape in a plan view, for example, when viewed from the thickness direction of the sheet 40. The sheet 40 may be square or rectangular in a plan view. The sheet 40 has a first edge portion 40A, a second edge portion 40B, a third edge portion 40C, and a fourth edge portion 40D, each constituting the four sides of the rectangle. The first edge portion 40A is parallel to the second edge portion 40B. The third edge portion 40C is parallel to the fourth edge portion 40D. The lengths of the first edge 40A, second edge 40B, third edge 40C, and fourth edge 40D in a plan view are 50% or more and 200% or less of the length of the continuous edge among the first edge 40A, second edge 40B, third edge 40C, and fourth edge 40D. The sheet 40 is formed in a planar shape, not linear. For example, the lengths of the first edge 40A, second edge 40B, third edge 40C, and fourth edge 40D in a plan view are, for example, 80% or more and 150% or less of the length of the continuous edge among the first edge 40A, second edge 40B, third edge 40C, and fourth edge 40D. The lengths of each edge portion 40A, 40B, 40C, and 40D of the sheet 40 in a plan view are, for example, 100 mm or more and 500 mm or less. The shape of the sheet 40 is not limited to a rectangular shape. For example, it may be elliptical. The shape and dimensions of the sheet 40 can be changed as appropriate. The maximum thickness of the portion of the planar heating element 10 on which the sheet 40 is provided is, for example, slightly greater than the maximum thickness of the heating body portion 20.

[0020] In this embodiment, the planar heating element 10 has a heating body 20 sandwiched between two sheets 40. The heat generated from the heating body 20 is transferred via the sheets 40 to the structure to which the planar heating element 10 is attached.

[0021] <Heating unit> As shown in Figure 1, the heating body 20 comprises a first wire 21, a second wire 22, and a plurality of heating elements 23 connected to the first wire 21 and the second wire 22, respectively. The ends 21A and 21B of the first wire 21 are exposed from the sheet 40. The ends 22A and 22B of the second wire 22 are exposed from the sheet 40. None of the plurality of heating elements 23 are entirely exposed from the sheet 40. The second wire 22 is positioned such that at least a portion of it runs parallel to the first wire 21. In a plan view, the lengths of the sides of the first edge 40A, the second edge 40B, the third edge 40C, and the fourth edge 40D are at least twice and no more than 100 times the distance from the first wire 21 to the second wire 22 in the portion where the first wire 21 and the second wire 22 run parallel. In a plan view, the lengths of the first edge 40A, the second edge 40B, the third edge 40C, and the fourth edge 40D are at least 5 times and no more than 30 times the distance from the first wire 21 to the second wire 22 in the portion where the first wire 21 and the second wire 22 are parallel.

[0022] The heating element 23 shown in Figure 3 contains ceramics made of barium titanate with additives. Multiple heating elements 23 all have similar dimensions. The heating body 20 further includes connecting members 24 that connect the heating elements 23 to the first wire 21 and the second wire 22. The connecting members 24 electrically connect the first wire 21 and the second wire 22 to the heating body 20. The heating elements 23 generate heat when current is supplied to them via the first wire 21 and the second wire 22.

[0023] As shown in Figures 2 and 4, the heating body 20 further comprises a covering portion 30 that covers the first wire 21, the second wire 22, the heating element 23, and the connecting member 24. The covering portion 30 in this embodiment corresponds to an insulating protective portion positioned between the sheet 40 and the first wire 21, the second wire 22, and the heating element 23. The covering portion 30 has electrical insulating properties. The covering portion 30 is, for example, flexible. The covering portion 30 is formed of a thermoplastic resin such as a soft polyvinyl chloride resin, a polypropylene resin, and a crosslinked polyethylene resin. The covering portion 30 may not be provided on at least a portion of the ends 21A, 21B of the first wire 21 and at least a portion of the ends 22A, 22B of the second wire 22. The covering portion 30 is not provided, for example, on the portion between two adjacent heating elements 23. In a state where the heating body 20 is not placed on the sheet 40, and the first wire 21, the second wire 22, the heating element 23, and the connecting member 24 are covered with the covering portion 30, the portions of the first wire 21 and the second wire 22 to which the connecting member 24 is not attached are relatively movable.

[0024] As shown in Figure 1, the first electric wire 21 includes a first portion 21C extending in a first direction X and a second portion 21D extending in a second direction Y different from the first direction X. The first direction X is a linear direction. The second direction Y includes a curved direction Y1. The first electric wire 21 extends from one side of the first direction X to the other, then folds back at the second portion 21D, and extends from the other side of the first direction X to the other. The first electric wire 21 includes, for example, a plurality of first portions 21C and one or more second portions 21D. By including a plurality of first portions 21C in the first electric wire 21, heat can be suitably dissipated from the entire planar sheet 40. By including a plurality of first portions 21C in the first electric wire 21, the area of ​​the sheet 40 can be increased, making it easier to form the sheet 40 in a planar shape. The planar heating element 10 includes, for example, a first portion 21C of N and a second portion 21D of N-1. N represents a natural number greater than or equal to 2. The planar heating element 10 in Figure 1 includes five first parts 21C and four second parts 21D. The number of first parts 21C is odd, and the number of second parts 21D is even. Because the number of first parts 21C is odd and the number of second parts 21D is even, one end 21A and the other end 21B of the first wire 21 are exposed from different edges 40A, 40B, 40C, and 40D of the sheet 40, respectively. In Figure 1, one end 21A of the first wire 21 is exposed from the first edge 40A, and the other end 21B is exposed from the second edge 40B. The number of first parts 21C may be even, and the number of second parts 21D may be odd.

[0025] The second wire 22 includes a third portion 22C extending in a third direction and a fourth portion 22D extending in a fourth direction different from the third direction. The third direction is a linear direction. The third direction is equal to the first direction X. The second wire 22 extends from one end of the third direction to the other, then folds back at the third portion 22C, and extends from the other end of the third direction to the first. The second wire 22 includes, for example, multiple third portions 22C and one or more fourth portions 22D. The planar heating element 10 in Figure 1 includes five third portions 22C and four fourth portions 22D. The number of fourth portions 22D is even. Because the number of fourth portions 22D is even, one end 22A and the other end 22B of the second wire 22 are exposed from different edges 40A, 40B, 40C, and 40D of the sheet 40, respectively. In Figure 1, one end 22A of the second electric wire 22 is exposed from the first edge 40A, and the other end 22B is exposed from the second edge 40B.

[0026] The second portion 21D of the first wire 21 includes, for example, a portion extending in a first curvature direction Y11, a portion extending in a straight direction Y2, and a portion extending in a second curvature direction Y12, in the portion where the first wire 21 is outside the second wire 22. The portion extending in the straight direction Y2 may be omitted. The straight direction Y2 is a direction inclined with respect to the first direction X. The portion extending in the first curvature direction Y11 is curved by 90 degrees. The straight direction Y2 is a direction perpendicular to the first direction X. The portion extending in the second curvature direction Y12 is curved by 90 degrees. The second portion 21D of the first wire 21 includes a portion extending in a third curvature direction Y13, a portion extending in a fourth curvature direction Y14, and a portion extending in a fifth curvature direction Y15, in the portion where the first wire 21 is inside the second wire 22. The portion extending in the third curvature direction Y13 curves 180 degrees. The portion extending in the fourth curvature direction Y14 curves 180 degrees. The portion extending in the fifth curvature direction Y15 curves 180 degrees.

[0027] The fourth portion 22D of the second wire 22 has the same shape as the second portion 21D of the first wire 21 in the portion where the first wire 21 is located outside the second wire 22, for example, in the portion where the first wire 21 is located inside the second wire 22. The fourth portion 22D of the second wire 22 has the same shape as the second portion 21D of the first wire 21 in the portion where the first wire 21 is located inside the second wire 22, for example, in the portion where the first wire 21 is located outside the second wire 22.

[0028] When the planar heating element 10 is attached to the flat surface of the structure, the first wire 21 is arranged such that its first portion 21C and second portion 21D are aligned on the same plane. When the planar heating element 10 is attached to the flat surface of the structure, the second wire 22 is arranged such that its third portion 22C and fourth portion 22D are aligned on the same plane. When the planar heating element 10 is attached to the flat surface of the structure, the first wire 21 placed on the sheet 40 is arranged so that it is aligned on the same plane. When the planar heating element 10 is attached to the flat surface of the structure, the second wire 22 placed on the sheet 40 is arranged so that it is aligned on the same plane. When the planar heating element 10 is attached to the flat surface of the structure, the first wire 21 and the second wire 22 placed on the sheet 40 are arranged so that they are aligned on the same plane.

[0029] As shown in Figure 5, the length of the second portion 21D of the first wire 21 is substantially equal to the length of the fourth portion 22D of the second wire 22. The length of the portion of the first wire 21 that is placed on the sheet 40 is equal to the length of the portion of the second wire 22 that is placed on the sheet 40. The length of the first wire 21 is equal to the length of the second wire 22. The length of the second portion 21D of the first wire 21 and the length of the fourth portion 22D of the second wire 22 are set so that the length of the portion of the first wire 21 that is placed on the sheet 40 is equal to the length of the portion of the second wire 22 that is placed on the sheet 40. Substantially equal means that the function obtained from the configuration is within a feasible range. A substantially equal dimensional difference is, for example, within 0.5%. In Figure 5, the length of the second portion 21D of the first wire 21 in the portion where the first wire 21 is outside the second wire 22 is slightly longer than the length of the fourth portion 22D of the second wire 22. The length of the second portion 21D of the first wire 21 may be equal to the length of the fourth portion 22D of the second wire 22.

[0030] Two adjacent heating elements 23 are arranged at a predetermined interval. The predetermined interval is defined as the distance from the center of one heating element 23 to the center of another adjacent heating element 23 in the direction in which the first wire 21 extends, when the heating elements are arranged to extend linearly from the first end 21A to the second end 21B of the first wire 21. Two adjacent elements refer to those adjacent in the direction in which the first wire 21 extends. The first predetermined interval L11 in the part corresponding to the first part 21C is different from the second predetermined interval L12 in the part corresponding to the second part 21D. Each of the multiple heating elements 23 is connected to the first wire 21 and the second wire 22 in the part where the first wire 21 and the second wire 22 run parallel to each other. None of the multiple heating elements 23 are provided in the parts corresponding to the second part 21D and the fourth part 22D. The second predetermined interval L12 between the two heating elements 23 closest to each end of the second section 21D and the fourth section 22D is longer than the length of the second section 21D and the length of the fourth section 22D. The second predetermined interval L12 is an integer multiple of the first predetermined interval L11. The second predetermined interval L12 is three times the length of the first predetermined interval L11. The second predetermined interval L12 may be an even or odd multiple of the first predetermined interval L11. The second predetermined interval L12 may be twice or four times the length of the first predetermined interval L11.

[0031] <Sheet> As shown in Figure 2, the sheet 40 includes a first sheet 50 and a second sheet 60 positioned on the opposite side of the heating element 20 from the first sheet 50. The maximum thickness of the first sheet 50 is thinner than the maximum thickness of the heating element 20. The maximum thickness of the second sheet 60 is thinner than the maximum thickness of the heating element 20.

[0032] The sheet 40 is flexible. The sheet 40 includes an insulating portion 41. The insulating portion 41 has electrical insulating properties. The insulating portion 41 is flexible. The insulating portion 41 includes, for example, a thermoplastic resin such as a soft polyvinyl chloride resin, a crosslinked polyethylene resin, and a fluororesin. The fluororesin includes, for example, PTFE (polytetrafluoroethylene) and FEP (Perfluoroethylene propylene copolymer, Tetrafluoroethylene hexafluoropropylene copolymer). The insulating portion 41 includes a first insulating portion 51 provided on the first sheet 50 and a second insulating portion 61 provided on the second sheet 60. The first insulating portion 51 and the second insulating portion 61 each constitute the outer surface of the planar heating element 10. At least one of the outer surfaces of the first sheet 50 and the second sheet 60 has a flattened shape. In this embodiment, the outer surface of the first sheet 50 has a flattened shape. Both the outer surface of the first sheet 50 and the outer surface of the second sheet 60 may have a flattened shape.

[0033] The sheet 40 further includes a heat transfer section 43 positioned between the insulating section 41 and the multiple heating elements 23. The heat transfer section 43 has a higher thermal conductivity than the insulating section 41. The heat transfer section 43 is, for example, a metal foil with excellent thermal conductivity, such as aluminum foil or copper foil. The heat transfer section 43 may be made of a material other than metal foil, as long as it has a higher thermal conductivity than the insulating section 41. The heat transfer section 43 is provided on only one of the first sheet 50 and the second sheet 60, for example. In Figure 2, the heat transfer section 43 is provided on the first sheet 50. The first sheet 50 on the side on which the heat transfer section 43 is provided is attached to the structure so as to be in contact with the structure. The heat transfer section 43 shown in Figure 1 has a shape that substantially corresponds to the entire sheet 40 in a planar view of the planar heating element 10. The heat transfer section 43 may have a shape that corresponds to the heating body section 20.

[0034] The sheet 40 further comprises an inner insulating portion 42. The inner insulating portion 42 has electrical insulating properties. The inner insulating portion 42 is flexible. The inner insulating portion 42 includes, for example, thermoplastic resins such as soft polyvinyl chloride resin, polypropylene resin, and crosslinked polyethylene resin. The inner insulating portion 42 includes a first inner insulating portion 52 provided on the first sheet 50 and a second inner insulating portion 62 provided on the second sheet 60.

[0035] The first sheet 50 includes at least one layer. The second sheet 60 includes at least one layer. The sum of the number of layers in the first sheet 50 and the second sheet 60 is 5 or more. The sum of the number of layers in the first sheet 50 and the second sheet 60 may be less than 5 or 6 or more. In the first sheet 50, a heat transfer section 43 is sandwiched between the first insulating section 51 and the first inner insulating section 52. The first sheet 50 is composed of a three-layer structure in which the first inner insulating section 52, the heat transfer section 43, and the first insulating section 51 are arranged in that order from the inside to the outside of the planar heating element 10. The second sheet 60 is composed of a two-layer structure in which the second inner insulating section 62 and the second insulating section 61 are arranged in that order from the inside to the outside of the planar heating element 10.

[0036] The planar heating element 10 is configured to dissipate heat from both the first sheet 50 and the second sheet 60. In this embodiment, since the first sheet 50 includes the heat transfer section 43, the amount of heat dissipated from the first sheet 50 is greater than the amount of heat dissipated from the second sheet 60. The second sheet 60 does not include the heat transfer section 43, but since the second sheet 60 does not contain any insulating material, heat can also be dissipated from the second sheet 60.

[0037] <Electrical Wiring> The first end 21A of the first wire 21 shown in Figure 1 is configured to be connectable to a power source, the first wire 21 of another planar heating element 10, the second wire 22 of another planar heating element 10, or the first end 22A of the second wire 22. The first end 22A of the second wire 22 is configured to be connectable to a power source, the first wire 21 of another planar heating element 10, the second wire 22 of another planar heating element 10, or the first end 21A of the first wire 21. The second end 21B of the first wire 21 is configured to be connectable to a power source, the first wire 21 of another planar heating element 10, the second wire 22 of another planar heating element 10, or the second end 22B of the second wire 22. The second end 22B of the second wire 22 is configured to be connectable to a power source, the first wire 21 of another planar heating element 10, the second wire 22 of another planar heating element 10, or the second end 21B of the first wire 21.

[0038] The first end 21A of the first wire 21 and the first end 22A of the second wire 22 may be connected to a single connector. The second end 21B of the first wire 21 and the second end 22B of the second wire 22 may be connected to a single connector.

[0039] A grounding wire 70 is connected to the heat transfer section 43. At least a portion of the grounding wire 70 is exposed from the sheet 40. The grounding wire 70 may be configured to be exposed from the sheet 40 bundled with at least one of the ends 21A, 21B, 22A, 22B. The grounding wire 70 may be connected to a single connector to which the first end 21A of the first wire 21 and the first end 22A of the second wire 22, or the second end 21B of the first wire 21 and the second end 22B of the second wire 22 are connected.

[0040] The planar heating element 10 can be used by connecting it to other planar heating elements 10. The heating body 20 is formed point-symmetrically with respect to the center point of the sheet 40 in a planar view, for example. When multiple planar heating elements 10 are connected to each other and attached to a structure, for example, the first sheet 50 of the first planar heating element 10 is positioned to contact the structure, and the second sheet 60 of the second planar heating element 10 is positioned to contact the structure. The second end 21B of the first wire 21 of the first planar heating element 10 is connected to the first end 22A of the second wire 22 of the second planar heating element 10. The second end 22B of the second wire 22 of the first planar heating element 10 is connected to the first end 21A of the first wire 21 of the second planar heating element 10.

[0041] The operation of this embodiment will now be explained. Conventional linear heaters, when attached to structures with planar sections, required bending the linear heater and temporarily fixing it with aluminum tape or the like while arranging it in a planar manner. The first wire 21 of the planar heating element 10 in this embodiment includes a first portion 21C extending in a first direction X and a second portion 21D extending in a second direction Y different from the first direction X in the sheet 40. Because the first wire 21 extends in multiple directions in the sheet 40, a wide area of ​​the structure can be heated by attaching one planar heating element 10 to a structure with a planar section.

[0042] The effects of this embodiment will now be explained. (1) The planar heating element 10 includes a first wire 21 in the sheet 40, which has a first portion 21C extending in a first direction X and a second portion 21D extending in a second direction Y different from the first direction X. This allows the area that can be heated by the planar heating element 10 to be increased. Therefore, by installing the planar heating element 10 on a structure, the planar portion of the structure can be heated appropriately, making the installation of the planar heating element 10 easier. In addition, with conventional linear heaters, when temporarily fixed with aluminum tape or the like, the fixing is not done properly, and the load on the wire of the linear heater increases. On the other hand, since the planar heating element 10 is placed on the sheet 40 with the first wire 21 including portions extending in the first direction X and the second direction Y, the sheet 40 can be attached to a structure including a planar portion without bending the sheet 40 as much as with a linear heater. Therefore, the load on the first wire 21 can be reduced, thus preventing a shortened lifespan for the planar heating element 10. In addition, in conventional linear heaters, the distance between the two wires is fixed, so when linear heaters are arranged in a planar manner in a meandering manner, if the spacing between the meandering parts of the linear heaters is narrowed, the bending angle of the bent parts of the linear heaters becomes larger. In the planar heating element 10, the first wire 21 and the second wire 22 are arranged on a flat sheet 40 in a bent state, so the spacing between adjacent first parts 21C can be narrower than in the case of linear heaters, while the bending angle of the bent parts of the first wire 21 and the second wire 22 is smaller. Therefore, the planar heating element 10 can have a larger number of heating elements 23 per unit area.

[0043] (2) Two adjacent heating elements 23 are arranged at a predetermined distance from each other, and the first predetermined distance L11 in the part corresponding to the first part 21C is different from the second predetermined distance L12 in the part corresponding to the second part 21D. With this configuration, the heating elements 23 can be installed at different predetermined distances in the first part 21C and the second part 21D.

[0044] (3) The second direction Y includes the curvature direction Y1. The length of the first wire 21 in the second portion 21D is substantially equal to the length of the second wire 22 corresponding to the second portion 21D. This configuration makes it possible to reduce the difference in length between the first wire 21 and the second wire 22. With this configuration, for example, a planar heating element 10 can be manufactured by arranging a heating element body 20 on the sheet 40 such that the length of the first wire 21 is the same as the length of the second wire 22. When the length of the first wire 21 is the same as the length of the second wire 22, the mounting position of the heating element 23 on the first wire 21 and the second wire 22 can be easily set. Therefore, the manufacturing of the heating element body 20 becomes easier.

[0045] (4) The sheet 40 includes an insulating portion 41. With this configuration, the first wire 21, the second wire 22, and the multiple heating elements 23 can be insulated from the outside of the sheet 40 by including the insulating portion 41 in the sheet 40.

[0046] (5) The sheet 40 further includes a heat transfer section 43 positioned between the insulating section 41 and the multiple heat-generating elements 23. With this configuration, the heat transfer section 43 can suitably transfer the heat generated by the multiple heat-generating elements 23 by transmission. In addition, since the sheet 40 has multiple layers, the strength of the sheet 40 can be improved.

[0047] (6) A grounding wire 70 is connected to the heat transfer section 43. With this configuration, the heat transfer section 43 can be grounded by the grounding wire 70 connected to the heat transfer section 43, so the planar heating element 10 can be used suitably.

[0048] (7) The sheet 40 may further be provided with an insulating covering portion 30 that is placed between the sheet 40 and the first wire 21, the second wire 22, and the multiple heating elements 23. With this configuration, the covering portion 30 can insulate the sheet 40 from the first wire 21, the second wire 22, and the multiple heating elements 23. In addition, since the covering portion 30 covers the entire first wire 21, the second wire 22, and the heating elements 23, the first wire 21, the second wire 22, and the heating elements 23 can be suitably insulated.

[0049] (8) The sheet 40 includes a first sheet 50 and a second sheet 60 positioned on the opposite side of the first sheet 50, sandwiching the first wire 21, the second wire 22, and the multiple heating elements 23. With this configuration, the first wire 21, the second wire 22, and the multiple heating elements 23 are sandwiched between the first sheet 50 and the second sheet 60, so that the first wire 21, the second wire 22, and the multiple heating elements 23 are suitably protected.

[0050] (9) The planar heating element 10 is configured to dissipate heat from both the first sheet 50 and the second sheet 60. With this configuration, both the outer surface on the first sheet 50 side and the outer surface on the second sheet 60 side can be used as heat dissipation surfaces.

[0051] (10) The ends 21A, 21B, 22A, and 22B of the first wire 21 and the second wire 22 are exposed from the portion sandwiched between the first sheet 50 and the second sheet 60. With this configuration, the ends 21A, 21B, 22A, and 22B of the first wire 21 and the second wire 22 can be connected to a power source, another planar heating element 10, or an electrical device different from the planar heating element 10.

[0052] (11) The sheet 40 is flexible. With this configuration, the planar heating element 10 can be deformed to conform to the shape of the structure. Therefore, the planar heating element 10 can make suitable contact with the structure.

[0053] (12) The sum of the number of layers in the first sheet 50 and the number of layers in the second sheet 60 is 5 or more. This configuration allows for suitable protection of the heat-generating body 20. The first sheet 50 has a first insulating portion 51 and a first inner insulating portion 52 which constitute two insulating layers. The second sheet 60 has a second insulating portion 61 and a second inner insulating portion 62 which constitute two insulating layers. This configuration allows for more suitable insulation of the heat-generating body 20.

[0054] <Example of changes> In addition to the embodiments described above, the planar heating element 10 of this disclosure may also be in the form of the following modifications and a combination of at least two mutually non-inconsistent modifications.

[0055] The heating element 23 may include materials other than ceramics that generate heat electrically. For example, the heating element 23 may include a resin composition having conductive powder such as carbon black in place of or in addition to ceramics.

[0056] As shown in Figure 6, in addition to the first sheet 50, the second sheet 60 may also have a heat transfer section 43. By arranging the heat transfer section 43 on both the first sheet 50 and the second sheet 60, both the first sheet 50 and the second sheet 60 can dissipate heat effectively. When the heat transfer section 43 is arranged on both the first sheet 50 and the second sheet 60, heat can be efficiently transferred to the structure regardless of which of the first sheet 50 or the second sheet 60 is in contact with the structure. Therefore, the user can use any desired side of the planar heating element 10 as the contact surface with the structure. The second sheet 60 in Figure 6 is composed of a three-layer structure in which the second inner insulating section 62, the heat transfer section 43, and the second insulating section 61 are arranged in that order from the inside to the outside of the planar heating element 10.

[0057] The sheet 40 does not have to have a heat transfer section 43. The planar heating element 10 does not have to have a covering section 30. In the planar heating element 10 shown in Figure 7, both the first sheet 50 and the second sheet 60 do not have a heat transfer section 43. If the sheet 40 does not have a heat transfer section 43, the grounding wire 70 may be omitted. The planar heating element 10 shown in Figure 7 does not have a covering section 30.

[0058] The sheet 40 does not necessarily have to include the insulating portion 41. For example, at least one of the first insulating portion 51 of the first sheet 50 and the second insulating portion 61 of the second sheet 60 does not include the insulating portion 41. In this modified example as well, the first wire 21 and the second wire 22 can be insulated by the covering portion 30 and the inner insulating portion 42.

[0059] The sheet 40 does not necessarily have to include the inner insulating portion 42. For example, at least one of the first inner insulating portion 52 of the first sheet 50 and the second inner insulating portion 62 of the second sheet 60 does not include the inner insulating portion 42. In this modified example as well, the first wire 21 and the second wire 22 can be insulated by the covering portion 30 and the insulating portion 41.

[0060] The arrangement of the first wire 21 and the second wire 22 can be changed as appropriate. Multiple first parts 21C do not have to be parallel to each other. In the heating body 20 shown in Figure 8, two adjacent first parts 21C are inclined toward each other with the second part 21D in between. The second part 21D includes one curved section that curves at an angle of 10 degrees or more and 90 degrees or less. In Figure 8 as well, the length of the second part 21D of the first wire 21 is substantially equal to the length of the part of the second wire 22 that corresponds to the second part 21D.

[0061] The second direction Y may include only the linear direction Y2. For example, the second portion 21D of the first wire 21 includes only the portion extending in the linear direction Y2 in the portion where the first wire 21 is outside the second wire 22, and does not include the portion extending in the first curvature direction Y11 or the portion extending in the second curvature direction Y12. In this modified example, for example, both ends of the portion extending in the linear direction Y2 are continuous with the first portion 21C.

[0062] As shown in Figure 9, both the outer surface on the first sheet 50 side and the outer surface on the second sheet 60 side may be formed with an uneven shape. Both the outer surface on the first sheet 50 side and the outer surface on the second sheet 60 side have an uneven shape that follows the unevenness of the heat-generating body 20, for example. In this modified example, for example, the heat-generating body 20 may be positioned inside the sheet 40 such that the distance between the heat-generating body 20 and the outer surface on the first sheet 50 side and the distance between the heat-generating body 20 and the outer surface on the second sheet 60 side are substantially equal.

[0063] The planar heating element 10 may comprise a plurality of heating body sections 20. If the planar heating element 10 comprises a plurality of heating body sections 20, the plurality of heating body sections 20 may or may not be electrically connected to each other.

[0064] • Sheet 40 may include only one of the first sheet 50 and the second sheet 60. In this modified example, when the planar heating element 10 is attached to a structure, the side on which the heating body portion 20 is exposed may be covered with an insulating material.

[0065] The first predetermined interval L11 and the second predetermined interval L12 may be the same. The first predetermined interval L11 may be longer than the second predetermined interval L12. The first predetermined interval L11 may be different for each part of the first part 21C.

[0066] The planar heating element 10 may be configured to dissipate heat from only one of the first sheet 50 and the second sheet 60. In this modified example, for example, the other of the first sheet 50 and the second sheet 60 includes an insulating portion.

[0067] At least one of the ends 21A, 21B, 22A, and 22B of the first wire 21 and the second wire 22 may be configured so as not to be exposed from the portion sandwiched between the first sheet 50 and the second sheet 60. In this modified example, a connector may be placed in the portion sandwiched between the first sheet 50 and the second sheet 60 to which at least one of the first wire 21 and the second wire 22 is connected.

[0068] • Sheet 40 does not need to be flexible. In this modified example, only one of the first sheet 50 and the second sheet 60 may be configured not to be flexible. The planar heating element 10 may include a non-flexible support member for supporting the flexible sheet 40.

[0069] <Note> The technical concepts that can be understood from the above embodiments and their respective modifications are described below. The symbols are shown as examples to aid understanding, and the components described in each symbol should not be limited to those indicated by the symbols.

[0070] [Note 1] A planar heating element 10, First electric wire 21 and, The second electric wire 22, Multiple heating elements 23 connected to the first wire 21 and the second wire 22, The device comprises the first electric wire 21, the second electric wire 22, and a planar sheet 40 on which the plurality of heating elements 23 are arranged. The sheet 40 includes a first sheet 50 and a second sheet 60 positioned on the opposite side of the first sheet 50, with the first wire 21, the second wire 22, and the plurality of heating elements 23 in between. The first sheet 50 includes at least one layer, The second sheet 60 includes at least one layer, The sum of the number of layers in the first sheet 50 and the number of layers in the second sheet 60 is 5 or more. Planar heating element 10.

[0071] [Note 2] The first sheet 50 is composed of a three-layer structure arranged in the order of a first inner insulating layer 52, a heat transfer layer 43, and a first insulating layer 51 from the inside to the outside of the planar heating element 10. The second sheet 60 is composed of a two-layer structure in which a second inner insulating portion 62 and a second insulating portion 61 are arranged in that order from the inside to the outside of the planar heating element 10. The planar heating element 10 as described in Appendix 1.

[0072] [Note 3] The first sheet 50 is composed of a three-layer structure arranged in the order of a first inner insulating layer 52, a heat transfer layer 43, and a first insulating layer 51 from the inside to the outside of the planar heating element 10. The second sheet 60 is composed of a three-layer structure in which the second inner insulating portion 62, the heat transfer portion 43, and the second insulating portion 61 are arranged in that order from the inside to the outside of the planar heating element 10. The planar heating element 10 as described in Appendix 1. [Explanation of Symbols]

[0073] 10... Planar heating element, 21... First wire, 21C... First part, 21D... Second part, 22... Second wire, 23... Heating element, 30... Covering part, 40... Sheet, 41... Insulation part, 43... Heat transfer part, 50... First sheet, 60... Second sheet, 70... Grounding wire, X... First direction, Y... Second direction, Y1... Curving direction, L11... First predetermined interval, L12... Second predetermined interval.

Claims

1. A planar heating element, First power line and, A second electric wire is arranged such that at least a portion of it runs along the first electric wire, Multiple heating elements connected to the first and second electric wires, The device comprises the first electric wire, the second electric wire, and a planar sheet on which the plurality of heating elements are arranged, The first electric wire includes, in the sheet, a first portion extending in a first direction and a second portion extending in a second direction different from the first direction. Planar heating element.

2. Two of the aforementioned heating elements are arranged so as to be separated by a predetermined distance. The predetermined interval in the part corresponding to the first part and the predetermined interval in the part corresponding to the second part are different, The planar heating element according to claim 1.

3. The aforementioned second direction includes the curvature direction, The length of the first wire in the second part and the length of the second wire corresponding to the second part are substantially equal. The planar heating element according to claim 1.

4. The aforementioned sheet includes an insulating portion, The planar heating element according to claim 1.

5. The sheet further includes a heat transfer portion disposed between the insulating portion and the plurality of heating elements. The planar heating element according to claim 4.

6. A grounding wire is connected to the heat transfer section. The planar heating element according to claim 5.

7. The system further comprises an insulating protective section disposed between the sheet, the first wire, the second wire, and the plurality of heating elements. The planar heating element according to claim 1.

8. The sheet includes a first sheet, a first wire, a second wire, and a second sheet positioned on the opposite side of the first sheet, sandwiching the plurality of heating elements. The planar heating element according to claim 1.

9. The first sheet and the second sheet are configured to dissipate heat from both sides. The planar heating element according to claim 8.

10. Both ends of the first and second electric wires are exposed from the portion sandwiched between the first and second sheets. The planar heating element according to claim 8.

11. The aforementioned sheet is flexible, The planar heating element according to claim 1.

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