Heating device

Abstract

A heating device having a large-area expanded carrier, two connection contacts, and at least one heating electrical conductor assembly on the carrier connected to the two connection contacts for electrical connection, wherein the heating electrical conductor assembly has a plurality of heating electrical conductors, the heating electrical conductors are connected to each other at connection points, the heating electrical conductors are wired as a whole to form parallel and series circuits between the two connection contacts, each set of at least three heating electrical conductors forms a closed mesh, the at least three heating electrical conductors are connected to each other at the connection points, and the heating electrical conductor assembly is applied on the carrier in a film configuration by a film method.

Description

[Technical Field]

[0001] The present invention relates to a heating device having a carrier, connecting contacts, and at least one heating electrical conductor assembly on the carrier having a plurality of heating electrical conductors. [Background technology]

[0002] EP 3145273 A1 discloses a heating device having a carrier on the outside of which a heating electrical conductor is attached. The carrier can be flat or tubular in shape. The heating electrical conductor runs in a serpentine pattern or in a loop with parallel tracks. The individual tracks acting as heating electrical conductors are connected in series (i.e., arranged in series) and connected to connecting contacts. The configuration options are limited by the purely serial connection of the heating electrical conductors. 65-80% of the surface area of ​​the carrier is covered by the heating electrical conductor, which allows for an extremely high surface density for high power output.

[0003] DE 102016225462 A1 discloses a heating device in which a grid or network of heating electrical conductors runs freely between connecting contacts that hold the heating electrical conductor assemblies. As a result, heat dissipation, particularly into the ambient air, is highly possible. The drawback is that using a carrier, for example in the form of a container wall or pipe wall, to heat water placed therein can provide poor or inefficient heating. Summary of the Invention

[0004] The object of the present invention is to provide a heating device as mentioned at the beginning, by which the problems of the prior art can be solved, in particular by which a heating device having a large-area carrier and at least one heating electrical conductor assembly thereon can be designed in a simple and essentially variable manner and it is possible to influence both the area output, on the one hand, in terms of the most uniform area output, and on the other hand, in terms of areas of high or low area output.

[0005] This object is achieved by a heating device having the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of additional claims and are explained in more detail below, the terms of which form part of the content of this description by express reference.

[0006] The heating device must have a large-area extended carrier. On the one hand, this can be flat and planar, on the other hand, it can be curved or designed as a groove, trough or tube. The heating device has at least two connection contacts and at least one heating electrical conductor assembly, each of which is arranged on the carrier. The heating electrical conductor assembly is connected to at least two connection contacts for electrical connection. The entire heating device can also have more than two connection contacts, for example, due to division or distribution of subgroups of heating electrical conductors. As a result, it is possible to achieve a heating that varies in terms of surface area or power in the heating device.

[0007] At least one heating electrical conductor assembly has a plurality of heating electrical conductors, for example, more than 50 or even several hundred. These heating electrical conductors are connected to each other at connection points so that they meet at said connection points. They are electrically connected to the connection points and thus electrically connected to each other. The heating electrical conductors are wired as a whole to form parallel and series circuits between the connection contacts. Advantageously, the heating electrical conductors form a network, particularly with connection contacts that act as nodes where they branch and reunite multiple times, so that precise subdivision or distinction between parallel and series connections is not possible. The heating electrical conductor assembly has a plurality of meshes, which are formed by at least three heating electrical conductors, so that the meshes, or at least the majority of them, are closed. The at least three heating electrical conductors are connected to each other or meet at connection points contained by this mesh. The heating electrical conductor assembly is advantageously applied to a carrier in a film configuration by a film method. Thick film methods are suitable for this, but also thin film methods, plasma spraying, or CVD and PVD methods. The heating and electrical conductors of the entire heating and electrical conductor assembly are preferably manufactured together, i.e., as part of a film construction, either in one step or in several steps.

[0008] The design of the heating electrical conductor assembly, which has a plurality of individual heating electrical conductors connected to one another in a network or grid-like fashion so that current flows through all of them, allows the individual heating electrical conductors to be arranged in a well-distributed manner relative to the area. Less than 60%, preferably less than 50% or even less than 40% of the surface area of ​​the carrier in the area of ​​the heating device can be directly covered, while at the same time the surface area of ​​the carrier in this area can be almost uniformly covered with heating electrical conductors. This makes it possible to heat the carrier in a very uniform manner or with a uniform areal output across the surface area, but with a lower overall power output than in the prior art. Therefore, the areal output is preferably related to the surface area of ​​the heating electrical conductor assembly or to the surface area continuously covered by the heating electrical conductors or heating electrical conductor assembly.

[0009] In an embodiment of the invention, one direction of the heating electrical conductor can be at an angle to the longitudinal extent of the connecting contacts, this angle being in the range of 2 to 85°. Thus, the heating electrical conductor can run neither parallel nor perpendicular to one of the connecting contacts, but at an angle between them or to it. The angle can advantageously be 35 to 60°, particularly advantageously about 45°. This makes it possible to achieve a uniform structure of the heating electrical conductor assembly.

[0010] It is advantageous for each heating electrical conductor to run straight, and in particular for all heating electrical conductors in a heating electrical conductor assembly to run straight. In this way, problems such as current crowding that can occur with curved heating electrical conductors are prevented in the first place. There are exactly two or exactly three directions in which the heating electrical conductors can run, and each heating electrical conductor can run along one of these directions.

[0011] In one embodiment of the present invention, at least 80% of the connection points, particularly preferably at least 95% of the connection points, can have the same number of heating electrical conductors connected to them. This means that there will be some exceptions in the amount of heating electrical conductors on the edge region of the heating electrical conductor assembly or on the carrier, where fewer or more heating electrical conductors will be provided or meet at the connection points. In the edge region of the heating electrical conductor assembly, this will be difficult to avoid. In general, fewer heating electrical conductors will be provided at the connection points. In this case, there will no longer be heating electrical conductors running in the free area adjacent to the edge region.

[0012] In further embodiments of the invention, exactly three heating electrical conductors or exactly four heating electrical conductors can meet at 95% or the majority of the connection points. A more uniform configuration of the heating electrical conductor assembly is also possible in this way. If three heating electrical conductors meet at the connection points, the associated mesh can be hexagonal or advantageously triangular, in particular equilateral. If four heating electrical conductors meet at the connection points, the associated mesh can advantageously be rectangular or square.

[0013] Advantageously, the mesh can be approximately hexagonal or honeycomb-shaped, preferably precisely hexagonal. In this case, four longitudinal sides of the hexagon can each be formed by a single heating and electrical conductor, and two opposite longitudinal sides of the hexagon can each be formed by a long connection point. The connection points are then of the long connection area type, and the heating and electrical conductors are preferably longer than the long connection points, in particular 50 to 300% longer.

[0014] In an advantageous development of the invention, most, in particular at least 80% or even at least 95%, of the heating electrical conductors run in a straight line. The straight design of most or all of the heating electrical conductors avoids the above-mentioned problems related to uneven current conduction along curved tracks, which can lead to undesirable uneven heat power distribution or damage to the heating electrical conductors and / or carriers.

[0015] In an alternative development of the invention, most of the heating electrical conductors are curved, in particular at least 80% of the heating electrical conductors. Advantageously, the heating electrical conductors are curved twice in opposite directions, in particular in an S-shape. The two arcs running in opposite directions are particularly advantageously curved uniformly. Such a design can be point-symmetrical with respect to a midpoint along the heating electrical conductor. As a result, the length of a curved heating electrical conductor between its end connection points, in particular a curved conductor that is curved once, twice or more times, is at least 5% greater than the straight length between these connection points. The length is preferably even greater, in particular at least 10% greater, for example at least 20% greater.

[0016] Curved heating electrical conductors, on the one hand, allow for higher resistance values ​​to be achieved for the heating conductor material with advantageous thickness and width of the electrical conductor due to the increased length for a given resistance. On the other hand, a good distribution of the area of ​​the heating electrical conductors, and therefore their generated heat output or heating, can occur over the entire surface area covered by the heating electrical conductor assembly. The heating electrical conductors can always run in a curved manner or not run straight in any area. Alternatively, they can run straight in one area, for example in the central area, where a change in curvature occurs.

[0017] In an advantageous development of the invention, a plurality of the heating electrical conductors, in particular at least 80% of the heating electrical conductors, have the same length. Advantageously, at least 95% of the heating electrical conductors have the same length, so that in practice only a small number of the heating electrical conductors have different lengths, since they are optionally arranged in the edge region or adjacent to the free surface region of the heating electrical conductors, as will be explained in more detail below.

[0018] Preferably, the majority of the heating electrical conductors have the same shape. This can be at least 80% of the heating electrical conductors, particularly advantageously at least 95% of the heating electrical conductors. They are therefore identical in terms of length, width, longitudinal extent, and thickness. If a uniform power supply is ensured by a suitable configuration of the heating electrical conductor assembly, there will also be a uniform heat output.

[0019] In one embodiment of the present invention, the angular region between two adjacent heating electrical conductors that meet or connect to each other at a connection point is not angular or sharp, but rather rounded. The rounding of this angular region can be such that it is rounded with a radius of at least 2% of the maximum width of one of the heating electrical conductors. In particular, this radius can be 5 to 100% or even 200%, preferably 20 to 50%, of the maximum width of the heating electrical conductor. This means that there is no discontinuous non-uniformity in the current distribution in this angular region. Due to the rounding, the cross section of the electrical conductor is slightly increased due to the larger width, which leads to a decrease in heat output. However, this can be limited by designing the radius so that it does not have an interference effect. In certain conditions, such rounding can also simplify the production of the heating electrical conductor assembly, for example, by screen printing.

[0020] At least 80% or at least 95% of the connection points can be rounded in the angled region, preferably in all angled regions of the connection points. The rounding can also be designed identically to ensure in each case the same design and the same behavior, especially during heating operations.

[0021] In a first embodiment of the invention, the connection point can be formed by two heating electrical conductors, each having the same width, crossing each other, in particular two heating electrical conductors, each of which can have the same width. The area covered by the longitudinal extents of the two heating electrical conductors then forms the connection point. The connection point can also be made in the same shape if not four, but only three heating electrical conductors are connected to it. These then do not need to extend beyond the connection point.

[0022] In the second embodiment of the present invention, the connection point can be a larger area than the simple intersection area corresponding to the first embodiment of the present invention, as described above. This can ensure that the same current density prevails in the area of ​​the connection point as in the heating electrical conductor itself, and therefore the heat output generation at the connection point is the same as or at least not greater than that of the heating electrical conductor itself. This can also possibly be achieved by increasing the film thickness rather than the area of ​​the connection point.

[0023] In a further embodiment of the invention, the heating electrical conductors can have different widths, preferably with a maximum width variation of 40%. The width variation of the heating electrical conductors should advantageously be a maximum of 25%. If the heating electrical conductors all have the same film thickness, the heat output can be generated locally or in specific areas in a varied manner. If the heating electrical conductors have the same length, a narrow heating electrical conductor will generate more heat output than a wide heating electrical conductor. In this way, the heat output or heating can be varied locally or in specific areas by the heating device.

[0024] Advantageously, the heating electrical conductor has a constant width over the area between the two connection points at its ends or over its length, so that at least in this heating electrical conductor the power generation is uniformly distributed over its length.

[0025] Alternatively, the heating electrical conductor may have a width that varies over its length or over the range between two connection points at its ends. The variation should be within the above-mentioned range of maximum 40% or even maximum 25%. Otherwise, the difference in heat output generation would be too great and there would be a risk of damage to the heating electrical conductor or heating device due to excessively high temperatures with uneven temperature distribution.

[0026] The width of the heating electrical conductor can preferably increase monotonically from one connection point to the other, or it can decrease monotonically. The width particularly preferably increases or decreases strictly monotonically.

[0027] In a further development of the invention, the thickness of the film of the heating electrical conductor assembly or the heating electrical conductor itself can be varied by a maximum of 20% or 10% so that it does not vary significantly. Advantageously, it can vary by a maximum of 2% or is the same everywhere, and is produced by a manufacturing method with at least the same nominal thickness. The heating electrical conductor assembly can be produced in a film configuration, for example, by a thin-film method, in which all materials for the heating electrical conductor can always be applied simultaneously in one step or in multiple steps in the same amount or with the same film thickness. This allows for a simple and practical manufacturing method.

[0028] In a further embodiment of the invention, the plurality of connection points may have only two heating electrical conductors in at least one region of the heating electrical conductor assembly, or only two heating electrical conductors may meet there. These heating electrical conductors preferably do not extend in a straight line but rather have an angle (e.g., in the range of 35 to 60°) relative to one another. However, in principle, these heating electrical conductors are advantageously equivalent to other heating electrical conductors in terms of width and / or length, or advantageously also in terms of thickness. It is particularly advantageous for these connection points with only two heating electrical conductors to be located in the edge region of the heating electrical conductor assembly or adjacent to a free surface area within the heating electrical conductor assembly. In this way, it can be achieved, on the one hand, that the heating electrical conductor assembly is the same everywhere or is the same over a large portion of the region of the heating electrical conductor assembly, and is formed in a particularly regular manner. The free surface area of ​​the heating electrical conductor assembly can be surrounded by heating electrical conductors and can be used to provide electrical connections or sensors (e.g., temperature sensors) through non-heated regions (areas without heating electrical conductors). Advantageously, they should not be heated too much or exposed too much to the heating effect of the heating electrical conductor. The edge area can be advantageously located towards such a free surface area. The free surface area can generally vary in size, but it has an area advantageously between 4 and 100 times, particularly advantageously between 10 and 40 times, the area of ​​the mesh. Advantageously, the free surface area is defined or completely bounded by the heating electrical conductor or by the heating electrical conductor assembly.

[0029] In a further embodiment of the invention, recesses can be provided in the edge region, so to speak, on the sides, of the heating electrical conductor assembly. Such recesses can be designed in the form of a depression, in which two or three heating electrical conductors are connected to each other in the region of this depression at adjacent or external connection points. Here, it is advantageous to connect exactly one heating electrical conductor or exactly two heating electrical conductors to each other less at the majority of the remaining connection points of the heating electrical conductor assembly. Thus, no heating electrical conductors run or protrude into the region of the depression.

[0030] The specified free surface area within the heating electrical conductor assembly is preferably designed so that it does not contain any heating electrical conductors or connection points. In this case, the free surface area should be bounded by heating electrical conductors that correspond to other regular assemblies of heating electrical conductors in the majority of the area of ​​the heating electrical conductor assembly. Depending on the design of the assembly or mesh of heating electrical conductors that meet at the connection points, the free surface area can be bounded by heating electrical conductors in linear ranges or directions relative to each other. Two or three (preferably three) heating electrical conductors can also be connected to each other at multiple connection points adjacent to the free surface area.

[0031] In an advantageous embodiment of the present invention, the surface heat output can vary by up to 25% within the surface of the heating electrical conductor assembly, particularly only where the heating electrical conductors run, i.e., without the above-mentioned free surface area. In particular, the surface heat output can vary by only up to 10%. It can be advantageous to use a heating device to generate as uniform a heat output as possible. Alternatively, variations in the surface heat output can also be used within the heating electrical conductor assembly to provide high heat output in specific areas. Due to the above-mentioned variations in the width of the heating electrical conductors, this is also particularly possible within a single heating electrical conductor assembly, particularly with continuous variations in the surface heat output. As a result, excessive variations in the heat output, which could possibly lead to damage, can be avoided.

[0032] In a further embodiment of the present invention, secondary connection contacts can be provided, connected to each of the connection contacts. Such secondary connection contacts can be located opposite each other in pairs in a direction perpendicular to the longitudinal extent of the connection contacts. If provided linearly, they can run parallel to the connection contacts. Each secondary connection contact is connected to a connection contact directly or via another secondary connection contact. They can be electrically connected to the connection contacts by a bridging contact. The secondary connection contacts are advantageously made from the same material as the connection contacts, particularly advantageously having the same width and thickness as the connection contacts. Thus, they can be manufactured together, for example. The bridging contacts should be designed slightly differently or from a different material so that they can be easily cut by laser or mechanical scribing. In this way, the heating electrical conductor assembly can be electrically adjusted after manufacturing to match precise values. Certain regions of the heating electrical conductor assembly (i.e., some heating electrical conductors) can possibly be completely or at least partially isolated from the power supply. This depends on whether the heating electrical conductors connected to the secondary connection contacts are electrically contacted only by them or whether they are also connected to other heating electrical conductors.

[0033] Large-area contacts can be applied to the heating electrical conductor assembly, designed in the form of strips and covering at least part of the width of the heating electrical conductor assembly transversely to its longitudinal extent, to create electrical contact. These large-area contacts are advantageously made of a material with good electrical conductivity, for example, similar to the material of the connecting contacts described above. The large-area contacts can be partially covered with a highly electrically conductive material for electrical adjustment to the desired value of electrical resistance, which then overlaps and contacts adjacent connecting contacts, secondary connecting contacts, or adjacent heating electrical conductor assemblies. This creates a kind of short circuit, thus shorting the heating electrical conductor assembly and resulting in a low electrical resistance. Advantageously, at least two such large-area contacts can be applied adjacent to each other at a small distance to adjust to different values ​​of resistance.

[0034] The width of such a large-area contact can increase in the direction of an adjacent connecting contact, secondary connecting contact, or adjacent heating electrical conductor assembly, especially at the end in this direction. The large-area contact can be at least 50% wider. In this way, it can be easily and well covered with a highly electrically conductive material for contact purposes, but it does not need to be the same width along its entire length. This saves material and minimizes the restriction of the heating function of the heating electrical conductor covered by it. Nevertheless, the large-area contact can be easily reached and therefore contacted. In general, the large-area contact can have a width that varies along its length. In particular, it can be wider from one narrow free end to the other, regardless of what it is adjacent to. The shape of the large-area contact can be a long, narrow triangle.

[0035] In an advantageous embodiment of the present invention, the heating device can have at least one additional heating electrical conductor assembly, which has two additional connection contacts and a single large-area additional heating electrical conductor running between them. This large-area additional heating electrical conductor is advantageously provided with a closed surface (i.e., uninterrupted). The surface of the additional heating electrical conductor is preferably rectangular. The additional heating electrical conductor can extend between the two additional connection contacts and run perpendicular to these additional connection contacts. Therefore, it should be longer than it is wide in the direction of current flow. It is advantageously at least 10 times longer than it is wide, and particularly advantageously at least 20 times longer. This can also be achieved with a heating electrical conductor assembly having a mesh of heating electrical conductors, each of which is in the form of a strip.

[0036] The width of the additional heating electrical conductor can be smaller than the width of the heating electrical conductor assembly with distributed heating electrical conductors. Its width can preferably be less than 50% of the width of the heating electrical conductor assembly so that its outer extent is significantly narrower. The area covered by the heating electrical conductor material can have the same dimensions, but it is also advantageously smaller.

[0037] The length of the additional heating electrical conductors can be 90 to 150% of the length of the heating electrical conductor assembly, and it is particularly advantageous for them to have the same length, so that the additional heating electrical conductors can have a length of 100 to 120% of the length of the heating electrical conductor assembly.

[0038] Overall, the heating device can have at least one or two heating electrical conductor assemblies according to the invention and at least two additional heating electrical conductors as described above. The area output can be different in each case: in particular, the heating electrical conductor assemblies according to the invention can have a varied area heat output. This is advantageously not possible with additional heating electrical conductors due to their continuous large-area design. In each case, the one or two heating electrical conductor assemblies and the two additional heating electrical conductors can run parallel to each other, the additional heating electrical conductors having a heating electrical conductor assembly according to the invention between them. However, multiple additional heating electrical conductors can also be provided in parallel with a single heating electrical conductor assembly according to the invention, the additional heating electrical conductors advantageously having a heating electrical conductor assembly between them.

[0039] In an embodiment of the present invention, an insulating and / or dielectric layer can be provided under the heating electrical conductor or between the heating electrical conductor and the carrier. This layer is at least as wide as the heating electrical conductor and at most 10 mm wider than the heating electrical conductor on both sides. Therefore, it protrudes under the heating electrical conductor by at most 10 mm, particularly at most 5 mm or 2 mm, and preferably at least 0.1 mm, on both sides. The extent of the insulating or dielectric layer can correspond to the extent of the heating electrical conductor or heating electrical conductor assembly, at least in the largest area of ​​the heating electrical conductor assembly. Within the mesh, the insulating or dielectric layer can have free spaces where no insulating or dielectric layer is provided or present. The metal surface of the carrier is exposed here.

[0040] In a further embodiment of the invention, a cover layer can be applied above or directly above the heating electrical conductor, and it can be at least as wide as the heating electrical conductor and at most 10 mm wider on both sides than the heating electrical conductor, thus exceeding the heating electrical conductor by at most 10 mm, particularly at most 5 mm or 2 mm. Advantageously, it protrudes beyond the heating electrical conductor by at least 0.1 mm on both sides. In this case, the width of the cover layer can be narrower overall than the insulating or dielectric layer, and therefore does not directly overlap the surface of the carrier. It is particularly advantageous for the extent of the cover layer to correspond to the extent of the heating electrical conductor or heating electrical conductor assembly, at least in the largest area of ​​the heating electrical conductor assembly. The cover layer can also have free spaces within its mesh where no insulating or dielectric layer is applied or present, again leaving the metal surface of the carrier exposed.

[0041] While full-area insulation is usually applied to a carrier and a full-area cover layer to the heating electrical conductor structure for the heating element using thin-film technology to ensure functional basic insulation and actual covering, the present invention allows, on the one hand, to save material itself, and, on the other hand, due to the reduced amount of material used for the insulation and cover layers and their behavior during cooling, especially due to their different thermal expansion coefficients, deformation of the materials used is reduced regardless of their shape. This is supported by the grid shape in addition to the use of less material: layers with a smaller surface area exert less deformation forces on the material.

[0042] The leakage current in this structure, especially in the insulating or dielectric layer, is also low.The printed area having the lattice or network structure or network shape is small compared to the total surface area.

[0043] In a further development, at least one connection contact can be designed as a lattice structure, preferably all connection contacts connected to the heating electrical conductor assembly or the heating electrical conductor. The lattice structure of at least one connection contact has a mesh with free spaces therein. In this way, the amount of contact material required can be reduced.

[0044] In one embodiment of the present invention, the heating electrical conductor assembly or its heating electrical conductors can be cut along free cutting sections, with the individual free cutting sections, which are connected and together form the free cut, preferably starting at the outer edge region of the heating electrical conductor assembly. They can cut the closed surface of the heating electrical conductor assembly so that the closed surface is electrically separated and electrically insulated from the rest of the heating electrical conductor assembly, thereby cutting the individual heating electrical conductors. The free-standing sections can cut the heating electrical conductors at an angle of 45 to 90 degrees, preferably greater than 55 degrees.

[0045] In a further embodiment of the present invention, additional linear tracks of heating electrical conductor material can be provided transverse to the general direction of current flow through the grid-shaped heating electrical conductor assembly between the two connecting contacts, advantageously running parallel to the connecting contacts. These linear heating electrical conductor tracks made of a heating electrical conductor material can advantageously run through the connecting points of the heating electrical conductors or mesh. They are intended to increase safety when operating the heating device in case local overheating occurs due to warm areas or so-called hot spots, which can lead to the combustion or destruction of one or more heating electrical conductors. Increased current concentrations of the current flow between the two connecting contacts then occur along these linear heating electrical conductor tracks, initiating local overheating in point-like areas, which can result in the combustion or destruction of the heating electrical conductors. These current concentrations then lead to the combustion of the heating electrical conductors, which can continue on one side or advantageously on both sides along the linear heating electrical conductor tracks, i.e., parallel to the connecting contacts, until the entire heating electrical conductor assembly between the two connecting contacts is severed. There is then no longer any current flow between the connection contacts or through the heating electrical conductor assembly, which is irreversibly damaged or destroyed, but at the same time it is ensured that operation with the defective heating electrical conductor assembly is no longer possible, and the heating device must then be replaced or repaired, but the safety against faulty operation is extremely high.

[0046] These and other features from the description and drawings, as well as the claims, may be realized in one embodiment and in another area of ​​the invention, either alone or in groups in the form of subcombinations, and may constitute advantageous embodiments entitled to the protection for which protection is sought here. The subdivision of the application into individual sections and subheadings does not limit the general validity of the text made under these headings. [Brief explanation of the drawings]

[0047] [Figure 1] FIG. 1 shows a plan view of a heating device according to the invention having a heating electrical conductor assembly on a carrier in a first embodiment of the invention. [Figure 2] FIG. 2 shows a heating device similar to that of FIG. 1 on a tubular carrier in a second embodiment. [Figure 3] FIG. 3 shows an enlarged view of the heating device of FIG. 1 showing the individual heating electrical conductors meeting at junctions to form a mesh in a third embodiment. [Figure 4] FIG. 4 shows a variant of a heating device similar to that of FIG. [Figure 5] FIG. 5 shows, in a fourth embodiment, a further heating device similar to that of FIG. 4 with a wide heating electrical conductor. [Figure 6] FIG. 6 shows, in a fifth embodiment, a further heating device having two identical heating electrical conductor assemblies connected in series. [Figure 7] FIG. 7 shows, in a sixth embodiment, a further heating device similar to the two heating devices of FIG. 6 connected in series. [Figure 8] FIG. 8 shows a seventh embodiment of a further heating device similar to that of FIG. 7, in which the first and fourth heating electrical conductor assemblies in series are designed to be different from the second and third heating electrical conductor assemblies. [Figure 9] FIG. 9 shows, in an eighth embodiment, a modification of the heating apparatus of FIG. 8 in which the first and fourth heating electrical conductor assemblies are replaced by large area heating electrical conductors. [Figure 10] FIG. 10 shows, in a ninth embodiment, a variation of the heating device of FIG. 9 having very narrow first and fourth heating electrical conductor assemblies and second and third heating electrical conductor assemblies therebetween having a very large mesh. [Figure 11] FIG. 11 shows a greatly enlarged view of a heating and electrical conductor assembly similar to that of FIGS. 1 and 3 with variations in the width of the heating and electrical conductors. [Figure 12] FIG. 12 shows a view of a recess in the edge region of a heating and electrical conductor assembly similar to that of FIG. 3, in which an electrically conductive track with connections for a temperature sensor protrudes laterally into this recess. [Figure 13]FIG. 13 shows an enlarged heating and electrical conductor assembly with a free surface area completely surrounded by the heating and electrical conductor, with holes provided in this free surface area. [Figure 14] FIG. 14 shows a heating and electrical conductor assembly similar to that of FIG. 3 with a C-shaped free cut that separates a region of the heating and electrical conductor from the remainder of the heating and electrical conductor assembly. [Figure 15] Figure 15 shows a further possible variant of a heating device similar to that of Figure 1, having secondary connection contacts parallel to the connection contacts, which are electrically connected to them by bridge contacts that can be disconnected. [Figure 16] FIG. 16 shows a variation of the heating device of FIG. 7 having intermediate junctions provided within the second and third heating electrical conductor assemblies. [Figure 17] FIG. 17 shows, in a tenth embodiment, a variant of a heating device similar to that of FIG. 9 with two intermediate contacts according to FIG. [Figure 18] FIG. 18 shows a variation of the heating device of FIG. 16 having large area contacts disposed on the second and third heating electrical conductor assemblies. [Figure 19] FIG. 19 shows a variation of the heating device of FIG. 18 having very narrow large area contacts disposed on the second and third heating electrical conductor assemblies. [Figure 20] FIG. 20 shows a close-up of the mesh of the heating and electrical conductor with rounded corners. [Figure 21] FIG. 21 shows a variation of the heating device of FIG. 3 with a fine quasi-hexagonal mesh. [Figure 22] FIG. 22 shows a variation of the heating device of FIG. 3 with individual heating electrical conductors bent into an S-shape. [Figure 23] FIG. 23 shows a variation of a heating device similar to that of FIG. 3, with individual heating electrical conductors bent into alternating S-shapes. [Figure 24] FIG. 24 shows a variation of the heating device of FIG. 22 having an insulating layer below the heating electrical conductor and a cover layer above the heating electrical conductor, both layers in the form of a lattice structure. [Figure 25-26] 25 and 26 show greatly enlarged views of a heating device according to FIG. 4 with connecting contacts having a lattice structure. [Figure 27] FIG. 27 shows a modification of the heating device of FIG. 9 having thin strip-shaped heating electrical conductors with parallel connections of grid-shaped heating electrical conductor assemblies therebetween. [Figure 28] FIG. 28 shows a variation of the heating device of FIG. 14 having a C-shaped free cut that runs in a zigzag pattern in the vertical region. [Figure 29] FIG. 29 shows a modification of the heating device of FIG. 1, in which additional heating electrical conductor tracks run parallel to the connecting contacts. [Figure 30] FIG. 30 shows a variation of the heating device of FIG. 19 with a differently configured large area contact. DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1 shows a first embodiment of a heating device 11 according to the present invention. The heating device 11 has a large-area, rectangular, elongated carrier 12, which has a flat design. The carrier 12 can be, for example, an electrically insulating ceramic, micanite, or metal substrate with an electrically insulating surface. The heating device 11 has a grid-shaped heating electrical conductor assembly 14 covering an elongated rectangular area. In this case, the heating electrical conductor assembly 14 overlaps two elongated, parallel connection contacts 16a and 16b made of a suitable contact material. Alternatively, the connection contacts 16a and 16b can overlap, i.e., be applied continuously, on the heating electrical conductor assembly 14 as shown here. On the left side, each of the connection contacts 16a and 16b terminates with a contact pad 18a and 18b for electrical connection, for example, by soldering or welding. The heating electrical conductor assembly 14 is advantageously manufactured by a thin-film method, in particular by screen printing in a known manner. This also advantageously applies to the connection contacts 16 and the contact pads 18 .

[0049] The heating device 111 according to the second embodiment of Fig. 2 can also be applied to a tubular carrier 112 rather than to a flat carrier 12. The tubular carrier 112 advantageously consists of a steel substrate with an electrically insulating surface, which can be formed, for example, by applying an insulating layer to the steel substrate. A heating electrical conductor assembly 114 corresponding to that of Fig. 1 can also be applied thereto, advantageously by a screen printing method. In this case, what is shown in Fig. 1 would be the unwound heating electrical conductor assembly of the heating device 111 of Fig. 2.

[0050] The connecting contacts 16a and 16b run parallel to each other. As can be seen from the enlarged view in Figure 3, the heating electrical conductor assembly 14 consists of a first plurality of heating electrical conductors 20a extending from the lower left to the upper right at a 45° angle to the connecting contacts 16a and 16b. It also consists of a second plurality of heating electrical conductors 20b extending from the lower right to the upper left, which is perpendicular to the direction in which the heating electrical conductors 20a run and thus at a 45° angle to the longitudinal direction of the connecting contacts 16a and 16b. The heating electrical conductors 20a and 20b meet at connection points 22, one of which is represented by a dotted circle. Therefore, the heating electrical conductors 20a and 20b are the short rectangular areas between the connection points 22. At these connection points 22, the film thickness is the same as that of the individual heating electrical conductors 20a and 20b. Therefore, the heating electrical conductors 20a and 20b are advantageously applied in a single printing process or thin film method, advantageously as a grid pattern by screen printing, rather than being applied one after the other or separately from each other with the connection points 22. Each of the plurality of heating electrical conductors 20a and 20b runs along a line that is only interrupted by the connection points 22. Due to the uniform design of the heating electrical conductor assembly 14, in which not only are the heating electrical conductors 20a and 20b identically designed within their same-directional grouping, but also all of the heating electrical conductors 20a and 20b are identically designed away from the edge regions 26, the same current density, and therefore the same area output, occurs on the surface of the heating electrical conductor assembly 14 during operation.

[0051] In each case, it can be seen that four heating electrical conductors 20, namely two parallel heating electrical conductors 20a and two parallel heating electrical conductors 20b, form a mesh 24. The mesh 24 is rectangular or square, except for the edge regions 26, which will be explained in more detail later. In particular, all meshes 24 are identical, except for the edge regions 26 and near the connection contacts 16.

[0052] 3, it can be seen that even in the connection point 22, the current density is not higher or is only insignificantly higher than in the heating electrical conductors 20a and 20b. This also applies to the heat output and temperature. Finally, the current flowing through one heating electrical conductor 20a and one heating electrical conductor 20b must flow through exactly one such connection point 22 and back into one heating electrical conductor 20a and one heating electrical conductor 20b.

[0053] FIG. 4 shows a third embodiment of a heating device 211 according to the present invention. The carrier 212 is not shown here with edge definitions. Similarly, for simplicity, the contact pads at the ends of the connecting contacts 216a and 216b are not shown. However, they are very easy to imagine. The heating electrical conductor assembly 214 is provided between two elongated, parallel connecting contacts 216a and 216b. In the central region, this corresponds to the heating electrical conductor assembly of FIG. 1 in terms of its lattice shape. Only in the edge region 226 can one see how the heating electrical conductors 220a and 220b are formed very long before they meet at the connection points with the heating electrical conductors in the other direction. Because each path of the electrical current between the connecting contacts 216a and 216b is the same length as in the central region of the heating electrical conductor assembly 214, except for non-uniformities within the connection points that affect the current, the same or very similar heat output can be achieved here. It goes without saying that the edge region 226 may still be slightly worn on a small scale, but generally run straight as in FIG.

[0054] Figure 5 shows a fourth embodiment of a heating device 311 according to the invention, which essentially corresponds to that of Figure 4, particularly in the edge region 326 of the heating electrical conductor assembly 314. The mesh area is similar to that of Figure 4, which means that fewer heating electrical conductors are provided overall than in Figure 4, due to the almost double width of the heating electrical conductors 320a and 320b of the heating electrical conductor assembly 314. The distance between adjacent heating electrical conductors in the same direction can approximately correspond to their width, and is therefore about half that of the heating device 211 of Figure 4.

[0055] A fifth embodiment of a heating device 411 according to the present invention is shown in FIG. 6. The heating device 411 comprises two heating electrical conductor assemblies 414a and 414b, which are apparently identical. Each heating electrical conductor assembly 414a and 414b covers an area in the shape of an elongated rectangular strip. However, here, the current flows longitudinally rather than transversely across the length of the heating electrical conductor assembly 414, as in the previous embodiment. Two connecting contacts 416a and 416b are provided on the left side, and one connecting contact 416c is provided on the right side, connecting the two heating electrical conductor assemblies 414a and 414b in series. This must be taken into account when determining the resistivity of the material of the heating electrical conductors 420a and 420b, as well as the supply voltage. The current path in the series circuit between the connecting contacts 416a and 416b is many times longer than in the heating device of FIG. 11, for example. Again, a mixture of series and parallel connections of individual heating electrical conductors 420 is seen.

[0056] FIG. 7 shows a sixth embodiment of a heating device 511 according to the present invention, in which two connecting contacts 516a and 516b are provided on the outside, between which four heating electrical conductor assemblies 514a-514d are provided in series connection. Further connecting contacts 516c, 516d, and 516e complete the series connection. Therefore, there is a much longer length of the current path between connecting contacts 516a and 516b to the outside. This must be taken into account when dimensioning, especially when selecting the resistivity of heating electrical conductors 520a and 520b. Furthermore, it can be noted that in the heating device 511 of FIG. 7, there are two or at most three meshes in the width direction of the heating electrical conductor assembly 514, whereas in the heating device 411 of FIG. 6, there are four meshes, and in the heating device of FIG. 3, there are eight complete meshes. At the same time, unlike in the heating device 411 of FIG. 6, the meshes are closed toward the edge regions (i.e., the current flows completely through them, thus contributing to the heating effect).

[0057] FIG. 8 shows a seventh embodiment of a heating device 611 according to the present invention. It is designed similarly to the heating device 511 of FIG. 7, but here a different type of heating electrical conductor assembly is provided on the carrier 612. Heating electrical conductor assembly 614a, which is very long relative to its width, is connected to connecting contact 616a. It is designed similarly to heating electrical conductor assembly 514a of FIG. 7, only with a slightly smaller mesh. Connecting contact 616c is provided at the right end, which connects it in series with a second heating electrical conductor assembly 614b. Second heating electrical conductor assembly 614b is almost identical to a third heating electrical conductor assembly 614c, which runs parallel to it and is only slightly shorter. The two are connected via connecting contact 616d. Heating electrical conductor assemblies 614b and 614c also have three adjacent meshes across their widths, like heating electrical conductor assembly 614a. Also, the width of the heating electrical conductors 614b and 614c is the same as that of the heating electrical conductor assembly 614a. However, the mesh has a larger or significantly larger area. They are all closed at the edge regions.

[0058] The fourth heating electrical conductor assembly 614d is connected to heating electrical conductor assembly 614c by connecting contact 616e and has connecting contact 616b on its left outer side. In principle, heating electrical conductor assembly 614d has the same design as heating electrical conductor assembly 614a, but is slightly shorter. Thus, heating device 611 can have multiple heating electrical conductor assemblies 614a-614d, which can generate different areal power densities. While the four heating electrical conductor assemblies 614a-614d are connected in series here, this does not have to be the case. They can also all be electrically connected to each other in parallel or a combination of parallel and series connections.

[0059] FIG. 9 shows an eighth embodiment of a heating device 711 according to the present invention. It is designed similarly to the heating device 611 of FIG. 8. However, the first and fourth heating electrical conductor assemblies 714a and 714d, which are the first-mentioned additional heating electrical conductor assemblies and have connecting contacts 716a and 716b, respectively, are designed as elongated strip-shaped heating electrical conductors corresponding to the first-mentioned heating electrical conductor assemblies over their entire area. The second and third heating electrical conductor assemblies 714b and 714c, which have the same pattern but slightly different lengths, are designed in the form of a grid with a maximum width of four meshes. Connecting contacts 716c, 716d, and 716e are provided for electrical interconnection.

[0060] Having such a heating device 711 on a carrier 712 allows for different distributions of different area powers to be achieved compared to FIG. 8. In this way, the first heating electrical conductor assembly 714a and the fourth heating electrical conductor assembly 714d can generate very high area powers, which are desired in the areas they cover. In the strip-shaped area between which heating electrical conductor assemblies 714b and 714c run, the area power can be somewhat lower, but it can still be very uniformly distributed. Heating electrical conductor assembly 714a is formed by a single wide heating electrical conductor 721a. Correspondingly, heating electrical conductor assembly 714c is formed by a single wide heating electrical conductor 721d.

[0061] A ninth embodiment of a heating device 811 according to the present invention is shown in FIG. 10 and is designed similarly to the heating device 711 of FIG. 9. Two heating electrical conductor assemblies 814a and 814d are formed on a carrier 812, which can be electrically contacted from the outside by two connecting contacts 816a and 816b. The heating electrical conductor assemblies 814a and 814d or the heating electrical conductors 821a and 821d are formed over the entire area but are significantly narrower than those shown in FIG. 9. They are connected in series with the second heating electrical conductor assembly 814b and the third heating electrical conductor assembly 814c by connecting contacts 816c, 816d, and 816e. The heating electrical conductor assemblies 814b and 814c are lattice-shaped, but with significantly larger meshes and heating electrical conductor widths corresponding to those shown in FIG. 9. The two mesh maxima are here given in the width direction of the heating electrical conductor assemblies 814b and 814c. However, it has a significantly lower area output than the heating device 711 of FIG.

[0062] Heating electrical conductor assembly 814a is formed by a single heating electrical conductor 821a, and heating electrical conductor assembly 814d is formed by a single heating electrical conductor 821d. Again, similar to heating device 711 of Fig. 9, a relatively high areal power can be generated in the strip-shaped area. In the area between heating electrical conductor assemblies 814b and 814c, where heating electrical conductor assemblies 814b and 814c run, the areal power is advantageously significantly lower, for example, by a factor of 2 to 4.

[0063] FIG. 11 shows an enlarged view of the heating electrical conductor assembly 14' to once again clearly show how the heating electrical conductors 20a' running from lower left to upper right and the heating electrical conductors 20b' running perpendicularly to the heating electrical conductors 20a' form a mesh 24'. Thus, each mesh 24 is surrounded by four heating electrical conductors 20' and four connection points 22'. In particular, it can be seen here how the widths of the heating electrical conductors 20a' and 20b' can vary. In the lower region, the heating electrical conductors 20a' and 20b' have a width B1. Width B1 can be, for example, 0.4 mm. The bottom row of the fully illustrated mesh 24' is precisely square.

[0064] In the second row of the mesh 24', shown fully below, the width of the heating electrical conductors 20a' and 20b' increases to width B2, which can be 0.5 mm, e.g., 25% greater than width B1. This increase in width is strictly monotonic, but not precisely continuous or uniform. For example, at a short distance from each connection point 22', approximately corresponding to the respective widths of the heating electrical conductors 20a' and 20b', these heating electrical conductors have a constant width before their width begins to increase. Thus, the second and third rows of the mesh 24' starting from below are not precisely square; only the top fourth row of the mesh 24', shown fully, is again precisely square. The distance between the longitudinal central axes of the heating electrical conductors 20a' and 20b' remains unchanged, but only by the width of the heating electrical conductors, i.e., the area of ​​the mesh 24' in the top row is somewhat smaller than the area of ​​the mesh 24' in the bottom row. However, varying the width of the heating electrical conductors 20a' and 20b' mainly affects their electrical resistance and therefore the heat power they generate, which means that if the current remains the same (which must be the case in this case), there will be a higher areal power in the lower region than in the upper region with wider heating electrical conductors.

[0065] 11, it is easy to imagine how the width of the heating electrical conductors can also vary by several times or even more, for example, and can be reduced again to width B1 or a different or smaller width. It is also easy to imagine that only the heating electrical conductors in one direction have a varying width, while the heating electrical conductors in the other direction have a constant width.

[0066] 11, it is easy to see that the variation of the electrical resistance of the heating electrical conductors can be achieved very easily by varying their width, especially easier than varying their length, which is extremely difficult to achieve within a regular grid. Also, varying the film thickness in thin film processes is extremely difficult and technically not easy to achieve consistently. In contrast, the shown variation of the width of the heating electrical conductors is relatively easy to achieve.

[0067] In FIG. 12, an enlarged view similar to FIG. 3 shows the edge region 26 of the heating device 11′. The heating electrical conductor assembly 14 now includes heating electrical conductors 20a and 20b, which form a closed mesh 24. A recess 28 is provided in the lower region, where some heating electrical conductors or some meshes (i.e., five meshes) are missing. The recess 28 is then bounded on the right side by the heating electrical conductors or closed meshes. From the left side, an assembly of two heating electrical conductor tracks 29 protrudes into or toward the recess 28, leading to a temperature sensor 31, shown here as a soldered SMD component. The temperature sensor 31 can be used to determine the temperature in this region on the carrier 12, for example, when the carrier 12 is in direct contact with water on the side facing away from the heating electrical conductor assembly 14 to heat the water. Because the recess 28 slightly increases the distance between the heating electrical conductor 20 and the temperature sensor 31, the temperature signal is not distorted by the direct heat output of the heating electrical conductors 20a and 20b. At the same time, the temperature sensor 31 does not need to be placed too far away from them, and as a result, it would not measure the correct temperature of the water, etc., being heated by the heating electrical conductor assembly 14. Furthermore, in FIG. 12, such a recess 28 in a conventional heating electrical conductor assembly 14 can be used to achieve an area with reduced area output or heat power generation.

[0068] Another possible development of the present invention is shown in FIG. 13 for a heating device 11 having a heating electrical conductor assembly 14. Within the regular heating electrical conductor assembly 14, the heating electrical conductors 20a and 20b run in different directions and form a mesh 24 between them. A so-called free surface area 33 is formed here. This was described above. The free surface area 33 does not include the heating electrical conductors 20a and 20b or their mesh 24. Here, there are no 16 meshes or heating electrical conductors forming them. Holes 35 are provided in the free surface area 33, into which, for example, bolts can be fastened or medium passages can be created. Instead of such holes 35 running through the carrier 12 of the heating device 11, fastening points for bolts or the like can be welded or electrical contacts can be provided. Due to the distance between the heating electrical conductors 20a and 20b and the holes 35, the temperature in this area can be adjusted according to the heat output. In particular, the temperature can be slightly reduced.

[0069] FIG. 14 shows how electrical adjustment of the resistance can be performed on the heating electrical conductor assembly 14 described with reference to FIGS. 1 and 3, as a similar embodiment of the heating electrical conductor assembly 14. In the right region, a free cut section with free cut sections 37a-37c is shown adjacent to the right edge region 26. The free cut section starts a short distance from the upper connection contact 16a in the right edge region 26 and runs parallel to it to the left as free cut section 37a. It cuts through 15 heating electrical conductors 20, or extends horizontally across eight meshes. It then turns downward at a right angle and cuts through 16 heating electrical conductors 20 as free cut section 37b. It runs until just before the lower connection contact 16b and then turns right at a right angle as free cut section 37c, i.e., parallel to the connection contact 16b but at a short distance, as described above. As a result, the area of ​​heating electrical conductor 20 and mesh 24 is electrically isolated from the remainder of heating electrical conductor assembly 14. The electrical resistance of heating electrical conductor assembly 14 or heating device 11 between connecting contacts 16a and 16b is thus increased, resulting in a reduction in overall heat output.

[0070] It is easy to see that this free cut does not necessarily have to have the three free cut sections 37a-c described above. It would also be equally effective if only two free cut sections 37a and 37c were provided parallel to the connecting contacts 16a and 16b. Some of the heating electrical conductors 20 separated by the vertical free cut section 37b would still be electrically connected. However, due to the long current path, significantly less or no current would flow through them, and therefore they would not exhibit a significant heating effect. Such a simplified free cut can save a certain amount of effort. The same would apply if only the central vertical free cut section and one of the other two free cut sections were cut free. Indeed, the complete free cut section 37 shown in FIG. 14 can affect the heating electrical conductor assembly 14 in a precisely predictable manner.

[0071] Further possibilities for influencing the electrical resistance in the heating device 11 are shown in the variant of FIG. 15. The heating electrical conductor assembly 14 itself is formed between the connecting contacts 16a and 16b as described above. In the right region, or toward the right edge region 26, three elongated secondary connecting contacts 39a are provided parallel to the upper connecting contact 16a at a small distance. They can be made of, for example, the same material. Their distance from the connecting contact 16a can be small and approximately correspond to its width. The electrical connection between the connecting contacts 16a and the secondary connecting contacts 39a is established in each case by a bridge contact 41a. This is advantageously made of a different material from the connecting contacts 16a and 39a, which should have similar electrical conductivity but inferior mechanical resistance. Therefore, it can be easily cut by friction or laser, and thus the bridge contact 41a can also be cut or removed relatively easily.

[0072] Correspondingly, three parallel secondary connection contacts 39b are provided near the lower connection contact 16b, each electrically connected to the connection contact 16b by a bridge contact 41b. The length of the current path between the secondary connection contacts 39a and 39b is approximately seven complete meshes 24, slightly less than that between the connection contacts 16a and 16b. By disconnecting the bridge contacts 41a and / or 41b, advantageously starting at the right toward the edge region 26 and then toward the left, certain sections or regions of the heating electrical conductor assembly 14 can be isolated in a manner similar to that shown in FIG. 14 and free cuts. Thus, the heat output generated at the connection contacts 16a and 16b can be adjusted at a fixed, predetermined voltage. As an alternative to disconnecting the bridge contacts 41a and 41b, the connection contacts 16a and 16b can also be interrupted longitudinally, with this interruption being closed by providing a corresponding extra bridge contact and electrically bridging it. When these bridge contacts are then disconnected, a reduction or minimization of the heating electrical conductor assembly 14 and an increase in electrical resistance are also possible.

[0073] Alternatively, it may not be possible to provide such bridge contacts from the start, but after measuring the electrical resistance, bridge contacts may be provided exactly where they are needed so that the desired electrical resistance can be achieved, thus saving unnecessary material costs.

[0074] FIG. 16 shows a variation of the heating device 511 corresponding to FIG. 7. Here, an intermediate contact 517 is provided transversely to the longitudinal direction of the central heating electrical conductor assemblies 514b and 514c, which acts as if the connecting contact 516d were shifted to the right. Like the connecting contact 516, the intermediate contact 517 should be made of a material with good electrical conductivity. Thus, the regions to the left of the heating electrical conductor assemblies 514b and 514c are not electrically activated or no longer have current flowing through them. As a result, the length of the heating electrical conductor assemblies 514b and 514c is shortened, and thus the electrical resistance between the connecting contacts 516c and 516e and the connecting contacts 516c and 516e is reduced. This can also be a form of electrical adjustment or variation of the heat output. Such an intermediate contact 517 can be applied to the heating electrical conductor assemblies 514b and 514c, for example, by subsequent printing or gluing. In this way, the overall heating resistance can be adjusted.

[0075] A tenth embodiment of a heating device 911 according to the present invention is shown in FIG. 17 and is designed in principle similarly to the heating device of FIG. 9 or 10. Two full-area heating electrical conductor assemblies 914a and 914b are provided in parallel and spaced apart from each other on a carrier 912 as heating electrical conductors 921a and 921d. Several connecting contacts 916a-916e are provided, which form series connections with heating electrical conductor assemblies 914b and 914c and are arranged between heating electrical conductors 921a and 921d, each having a grid shape and a width of three meshes 924. As in FIG. 16, an intermediate contact 917 is provided slightly to the right of connecting contact 916d, which establishes a direct electrical connection. Thus, the areas of heating electrical conductor assemblies 914b and 914c are separated to the left of this. Similarly, an intermediate contact 917′ is provided between heating electrical conductor 921a and heating electrical conductor assembly 914b. This intermediate contact 917' acts like the connecting contact 916c shifted to the left, i.e., it also acts as a shortening of each heating electrical conductor assembly. Therefore, such shortening by the intermediate contact can be provided not only between the grid-shaped heating electrical conductor assemblies, but also between the grid-shaped heating electrical conductor assembly 914b and the wide, full-area heating electrical conductor 921a.

[0076] As a further variant of the heating device 511 similar to that of FIG. 7, FIG. 18 shows how multiple large-area contacts 543 can be provided by exactly one heating electrical conductor assembly 514b or 514c in each case. The large-area contacts 543 can be made of the material of the connecting contact 516, or alternatively, a material with very good electrical conductivity, which can also be easily or well contacted on its surface. In this case, pairs of these large-area contacts 543 are provided in the range of the two heating electrical conductor assemblies 514b and 514c, respectively. They are used so that an intermediate contact 517 can be provided to such pairs, similar to FIGS. 16 and 17. Electrical contact with these large-area contacts 543 is much better possible than electrical contact with the heating electrical conductor assembly 514 itself. The length of the two heating electrical conductor assemblies 514b and 514d can be varied at one of four points, possibly by short-circuiting, for relatively precisely graded, predetermined electrical adjustments. Therefore, the large area contact 543 serves to simplify or improve the application of the intermediate contact 517 .

[0077] In general, it is considered important for the present invention that the grid shape of the heating electrical conductor assembly of the heating device according to the present invention can be created by the intersection or overlap of linear heating electrical conductors. However, the film thickness of the entire heating electrical conductor assembly should be as uniform as possible, especially in the areas of the heating electrical conductors themselves and in the areas of such connection points. This makes it easier to create and provide a heat output that is generated as uniformly as possible.

[0078] Special thin film pastes, which may contain graphite, can be used as materials for the production of heating electrical conductors, especially for production using the thin film method. Alternatively, other materials with good electrical conductivity can be used, which can be advantageously used for the production of heating electrical conductors.

[0079] As a further variation of the heating device of FIG. 18, FIG. 19 shows how large-area contacts 543′ are designed to be extremely narrow in a heating device 511′ according to the present invention. As in FIG. 18, these large-area contacts 543′ cross the entire width of heating electrical conductor assembly 514b′, which is basically designed similarly to that of FIG. 18. It can be clearly seen that these large-area contacts 543′ are designed to be significantly narrower than in FIG. 18. They can also be made of the material of connecting contact 516c′, or a material with very good electrical conductivity, which can then be easily or well contacted to its surface. A narrow full-area heating electrical conductor 521a′ runs parallel to heating electrical conductor assembly 514b′, for example, as in FIG. 17.

[0080] To achieve the electrical contact described above for electrical adjustment, one of two narrow large-area contacts 543' can be provided by a specially printed intermediate contact, shown to the left of intermediate contact 517' in dotted lines, which acts as a type of bridge contact. Thus, heating electrical conductor 521a' and heating electrical conductor assembly 514b' can be shortened for electrical resistance adjustment, as described above. Due to the narrow configuration of large-area contact 543', less material is required for them while at the same time providing sufficiently good electrical conductivity. Furthermore, the current and heating behavior in heating electrical conductor assembly 514b' are impaired as little as possible. In the upper region, large-area contact 543' has a wide portion 544', which conforms in shape to those of the two adjacent heating electrical conductors 520', i.e., maximizes the use of the available surface area. As a result of this wide portion and the increased area available at wide portion 544', intermediate contact 517', shown in dotted lines, can overlap more widely, resulting in better electrical contact. It is also easy to apply the large area contact 543' to the intermediate contact 517'.

[0081] FIG. 20 shows an enlarged view of the heating electrical conductor assembly 14, including the heating electrical conductors 20a and 20b, forming a mesh 24 between the heating electrical conductors 20a and 20b. As a special feature, the mesh 24 has rounded corners or corners with a radius r, which is shown as an example. The rounding or chamfering is uniform throughout the mesh 24 and throughout all of the meshes 24. The radius r is approximately 70% of the width of the heating electrical conductors 20a and 20b, all of which have the same width. The rounding at the radius r, on the other hand, allows for simplified or improved manufacturing. For example, as can be seen from the enlarged view of FIG. 11, perfectly sharp corners are not easily produced for the aforementioned small width structures of the heating electrical conductors 20 in the range of less than 1 mm (e.g., 0.4 mm or 0.5 mm) using the screen printing method, a proven thin-film process. This can be improved by rounding.

[0082] Furthermore, the area of ​​the connection point 22 can be increased by this rounding, so that current constrictions with increased current concentrations that could lead to damage do not occur at the corners. Furthermore, the generation of heat power can be reduced in the area of ​​the connection point 22. The temperature increase in the area of ​​the corners that occurs without rounding is estimated to be 4°C or even higher. This can be reduced or prevented by rounding. The excessive increase in temperature in the area of ​​the connection point 22 can also be reduced to less than 4°C, so that it no longer has a harmful effect or is barely noticeable.

[0083] FIG. 21 shows a variation of the heating electrical conductor assembly 1014, which can be seen as a grid pattern or lattice similar to the heating electrical conductor assembly 14 of FIG. 3. However, the mesh 1024 formed by the heating electrical conductors 1020a and 1020b is approximately hexagonal or honeycomb-shaped. Alternatively, they can also be considered diamond-shaped. This results from the fact that the individual heating electrical conductors 1020a and 1020b run parallel to each other, but each starts from a connection point 1022 and is slightly offset from each other, specifically by their respective widths. As a result, the connection point 1022 also has a larger surface area than the area of ​​the two intersecting heating electrical conductors 1020a and 1020b, for example, according to FIG. 6. In FIG. 21, it can be seen that the heating electrical conductors 1020a are at an angle of approximately 120° to each other, which is assumed to be given a regular pattern.

[0084] Another alternative variation of the heating electrical conductor assembly 1114 is shown in FIG. 22. This corresponds to the further aspect of the invention described above, in which the heating electrical conductors 1020a or 1020b do not run in a straight line between the individual connection points 1122, but rather are curved or double-curved, i.e., approximately S-shaped. As a result of this multiple or double bends in opposite directions, the heating electrical conductors 1020a and 1020b can be longer between the connection points 1122 than if they ran directly. The increase in length here can be 5% to 20%. This makes it possible to achieve a slightly higher resistance value due to the increased length for a given resistance value for the heating electrical conductor 1120 material with the acceptable thickness and width of the electrical conductor. Furthermore, the extent of the heating electrical conductor 1120 can be better distributed over the entire area covered by the heating electrical conductor assembly 1114. Here, it can be clearly seen that the heating electrical conductor 1120 is curved twice in opposite directions and always runs in a curved manner or does not run straight in any section. Of course, this can also be varied in that straight sections can be provided along the way where the change in curvature occurs. However, by avoiding such straight sections, the length of the heating electrical conductor 1120 can be made a little longer. Furthermore, the distribution over the entire area of ​​the heating electrical conductor assembly 1114 can be made better for more uniform heating. The connection points 1122 are formed here by slightly overlapping the heating electrical conductors with each other.

[0085] From the view of the heating and electrical conductor assembly 1114 according to Fig. 22, it can be seen that its longitudinal extent is from left to right as in Fig. 21. The individual heating and electrical conductors 1120 can also be seen as a kind of continuous wavy curves or wavy lines, each of which is arranged in mirror image of the other and is positioned relative to one another in a direction transverse to the left-to-right longitudinal extent. However, this basically corresponds to a rounding of the lattice structure of Fig. 3, which then gives exactly straight heating and electrical conductors, which are always positioned within one another.

[0086] Figure 23 shows yet another heating electrical conductor assembly 1214 having heating electrical conductors 1220a and 1220b that are curved twice in opposite directions, similar to Figure 22. It is also easy to imagine that the pattern of heating electrical conductor assembly 1214 in Figure 23 could be formed by flipping the pattern of heating electrical conductor assembly 1114 in Figure 22 from left to right. Additionally, heating electrical conductor 1220 is slightly wider in Figure 23.

[0087] In Figure 23, it can be seen that the length of heating electrical conductors 1220a and 1220b between connection points 1222 is 10-20% longer than in the case of straight heating electrical conductors arranged as ranges of one another according to Figure 3. The resulting grid pattern is regular, but it differs in the longitudinal direction of heating electrical conductor assembly 1214 from left to right, as opposed to the transverse direction, i.e., longitudinal compression. In Figure 22, heating electrical conductor assembly 1114 is compressed laterally. In the case of the heating electrical conductor assembly of Figure 3, this is the same in both directions.

[0088] FIG. 24 shows a heating device 1311, a variant of the heating device from FIG. 3. The heating device 1311 has an electrically conductive carrier 1312, for example, made of a steel substrate. An insulating layer 1346 in a lattice structure is applied to the upper side of the carrier 1312. It is metallic and therefore electrically conductive, which makes it unsuitable for the heating and electrical conductor assembly. It is advantageously formed by a dielectric glass film, which is electrically insulating even at the nominal operating temperatures for such a heating device 1311, e.g., 200-500°C. It can be applied by the method mentioned above, by which the heating and electrical conductor assembly is also applied, advantageously using a thin film method by screen printing. The lattice structure of the insulating layer 1346 leaves free spaces 1350 in the mesh 1324, where the normal surface of the carrier 1312, i.e., the steel surface, is exposed. In FIG. 24, the amount of material consumed for the insulating layer 1346 can be reduced by about 20-30% compared to covering the entire carrier 1312 with the insulating layer 1346 over the entire required area.

[0089] The heating electrical conductor assembly 1314 with the heating electrical conductors 1320 runs along the insulating layer 1346, particularly through its center, following the grid structure of the insulating layer 1346. These are applied to the insulating layer 1346 in the manner described at the beginning, again advantageously by a thin-film method using a screen printing process, and then fired in a known manner. The heating electrical conductors 1320 also form the mesh 1324 described above. On the left and right, the heating electrical conductors 1320 are in contact with elongated connecting contacts 1316, which are also applied to the insulating layer 1346 before or after the heating electrical conductors 1320, advantageously by screen printing in a thin-film method. Thus, again, electrical contact is made to the heating electrical conductor assembly 1314, as in the case of FIG. 1 or 3 described above.

[0090] The cover layer 1348 is applied over the heating electrical conductor assembly 1314, while electrically insulating the connecting contacts 1316, which can have, for example, dielectric properties. On the other hand, it is resistant to environmental influences, in particular it protects the heating electrical conductors 1320 and the connecting contacts 1316 against corrosion or permanent contact with oxygen. The cover layer 1348, in particular like the insulating layer 1346, can also be glass-like or designed as a cover glass and can be applied by a thin-film method, in particular screen printing, and then fired.

[0091] In FIG. 24, it can be clearly seen that the heating electrical conductor 1320 runs in the center of the web or across both the insulating layer 1346 with a lattice structure and the cover layer 1348 with a lattice structure. The width of the heating electrical conductor 1320 is approximately 1 mm, as described above for FIG. 11, and can be constant or slightly variable. Even if the width of the heating electrical conductor 1320 varies, it should run in the center, particularly between the insulating layer 1346 and the cover layer 1348, or these two should protrude beyond the heating electrical conductor 1320 by the same distance on both sides. In this case, the insulating layer 1346 can overhang or protrude below the heating electrical conductor 1320 by approximately 2 mm on both sides. The cover layer 1348 should protrude above the heating electrical conductor 1320 by approximately 1 mm or overlap the insulating layer 1346 on both sides. Thus, a sufficiently good insulation against leakage currents and in particular a high level of protection of the heating electrical conductor 1320 against environmental influences can now be achieved.

[0092] 1, the connection contacts 1316 should be guided to contact pads (not shown here). To do this, the contact pads must also run on the insulating layer and not be covered by the cover layer.

[0093] Holes 1335 through the carrier 1312 can be provided in the mesh 1324 or in the free space 1350 according to Figure 13. Alternatively, bolts, pins etc., especially for electrical contacts, can be attached or welded.

[0094] While we have discussed above how much material can be saved for the insulating layer 1346, it can be seen that an even narrower strip of the cover layer 1348 on the heating electrical conductor 1320 can also significantly reduce the material consumption for this cover layer 1348. A savings of approximately 40-50% can be achieved compared to the full-area design. Therefore, the strips of the insulating layer 1346 are approximately 5 mm wide; they should be a maximum of 10 mm wide. The strips of the cover layer 1348 are approximately 3 mm wide, and the heating electrical conductor 1320 itself is approximately 1 mm wide. The free space 1350 within the mesh is approximately 6 mm x 6 mm.

[0095] 25 and 26 show yet another heating device 1411 with a carrier 1412 as a steel substrate. The heating electrical conductors 1420 of a grid-shaped heating electrical conductor assembly 1414, similar to that of FIG. 24, run centrally on an insulating layer 1446 in a grid structure according to FIG. 24. The geometric dimensions, material, and application method also correspond to those of FIG. 24. Instead of the strip-shaped connecting contacts of FIG. 24, here there are connecting contacts 1416 in the form of a grid or as a grid structure, as mentioned at the beginning. The grid-shaped connecting contacts 1416 are applied to the heating electrical conductors 1420 and are advantageously printed on the connecting areas 1420' pointing to the left. In this way, it can be achieved that not only the insulating layer 1446 and the cover layer 1448 but also the connecting contacts 1416 are implemented on the heating electrical conductors 1420 in a grid structure, thus saving material. Generally, this can be advantageous in the case of heating electrical conductors 1420 with low current densities in the contact area, where the minimum electrical conductor track width is limited or restricted by manufacturing errors, for example, by screen printing. The material consumption for the connecting contacts 1416 can be adapted to the actual required electrical conductor cross-section, as well as the actual current density. Furthermore, when the current density is reduced by changing the mesh size of the lattice structure of the connecting contacts 1416, the electrical conductor track width, and possibly the film thickness of the connecting contacts 1416, and the electrical conductor cross-section can be adapted to such reduced current density. For such individual electrical conductors of the lattice-shaped connecting contacts 1416, their width can be, for example, 0.1 to 0.3 mm, but thin-film pastes with a very high silver content or resistive materials with a correspondingly high silver content can be used, and their electrical resistance is very low. However, because the consumption is very low, an overall cost advantage can be achieved.

[0096] 24, it can be seen that a cover layer 1448 is applied over the heating electrical conductor 1420 and over the connecting contacts 1416. It covers the connecting contacts 1416 except for the contact pads, which are not shown, and thus protects them from external influences, in particular corrosion. Here again, the heating electrical conductor 1420 runs centrally or is centered within the lattice structure of the insulating layer 1446 and the cover layer 1448.

[0097] FIG. 26 shows the upper left corner area of ​​the heating device 1411 based on FIG. 24, and FIG. 25a shows the lower left corner area. The lattice structures of the two connection contacts 1416 and 1416' in FIG. 26 are different. While the width of the individual electrical conductors of the connection contact is the same, in FIG. 25, four individual electrical conductors extend in a zigzag manner along the length of the connection contact 1416. In FIG. 26, three electrical conductors extend in a zigzag shape corresponding to the longitudinal extent of the connection contact 1416'. In this way, an embodiment corresponding to, for example, FIG. 11 can be achieved with different widths of the heating electrical conductors 1420 and their respective current densities. The mesh 1424 or free space 1450 here is square, not just quadrangular or rectangular.

[0098] Figure 27 shows a heating device 1511 as a variant of the heating device 711 of Figure 9, which comprises a carrier 1512 having an insulating layer 1546 on its surface according to Figure 24, onto which a heating electrical conductor assembly 1514 is then applied. Elongated connecting contacts 1516 are provided on the left and right between two connecting contacts 1516. Four parallel narrow heating electrical conductors 1521 run at the top between the two connecting contacts 1516, and four parallel narrow heating electrical conductors 1521 also run at the bottom. Between these two assemblies of parallel heating electrical conductors 1521, a lattice-shaped arrangement of heating electrical conductors 1520 according to Figure 24 extends as heating electrical conductor assembly 1514. All heating electrical conductors 1520 and 1521 and connecting contacts 1516 are covered with a cover layer 1548 as explained above, leaving free space 1550 in the area of ​​the heating electrical conductors 1520. Therefore, the heating device 1511 of Fig. 27 is a parallel circuit, which may allow for a possibly more uniform temperature distribution of the heating device 1511.

[0099] FIG. 28 shows a heating device 1611, a variation of the heating device 11 of FIG. 14, having a carrier 1612 with an insulating layer (not shown) on top of which extend two parallel, horizontally extending connection contacts 1616 and heating electrical conductor assembly 1614. The individual heating electrical conductors 1620 of the heating electrical conductor assembly 1614 do not form a square mesh as in FIG. 14, but rather form a diamond-shaped mesh 1624, similar to that of FIG. 23. Here, it is important that the heating electrical conductors 1620 of the individual mesh 1624 are cut by the free cut 1637 approximately in the middle of the heating electrical conductor 1620 between the connection points 1622, at least along the vertical extent of the free cut area 1637b. The horizontal free cut areas 1637a and 1637c are implemented in straight lines; otherwise, incorrect operation of the heating electrical conductor assembly 1614 may occur. The angle at which the individual heating electrical conductors 1620 are cut along the vertical free cutting section 1637b should be as close to a right angle as possible, advantageously at least 45° or at least 55°. This angle is here about 60°. This results in the zigzag path of the free cutting section 1637b shown here.

[0100] In the case of the heating device 1711 of FIG. 29, two parallel connection contacts 1716 are arranged on a carrier 1712, on which an insulating layer 1746 is provided. A grid-like heating electrical conductor assembly 1714 with individual heating electrical conductors 1720 forming a square mesh 1724 extends between them. As a special feature, three transversely running heating electrical conductor tracks 1723 are provided here, which are made of the same material as the heating electrical conductors 1720 and are advantageously applied in the same process. They run through the connection points 1722 of the heating electrical conductors 1720 and the mesh 1724. They increase safety when operating the heating device 1711, as hot spots and therefore local overheating could occur, for example by burning one side of the medium, which could lead to the combustion or destruction of one of the heating electrical conductors 1720. Starting from local overheating, there is an increased current concentration between the two connection contacts around this burned and destroyed heating electrical conductor 1720, essentially as a small or point-like area. These current concentrations then lead to the burning of further heating electrical conductors. This burning or destruction can continue on one or both sides along one of the linear heating electrical conductor tracks 1723, particularly approximately parallel to the connection contact 1716, until the entire heating electrical conductor assembly 1714 between them is severed. At that point, no current can flow through the heating electrical conductor assembly 1714, which is irreversibly destroyed.

[0101] Due to the course of the heating electrical conductor track 1723 transverse to the main direction of current flow between the connecting contacts 1716, the heating electrical conductor track 1723 has no effect when the heating electrical conductor assembly 1714 is operating properly and is therefore destructive.

[0102] Yet another heating device 1811 is shown in FIG. 30 , in which the heating electrical conductors 1820 of the heating electrical conductor assembly 1814 are designed as meshes having a shape corresponding to that of FIG. 23 , but are narrower or more compressed horizontally. In a variation of the large-area contacts 543 of the heating device 511 of FIG. 18 or the large-area contacts 543′ of the heating device 511′ of FIG. 19 , the large-area contacts 1843 are now designed so that a wide or rectangular region 1825 of heating electrical conductor material is provided between two sections of the heating electrical conductor 1820. Similar to the connecting contacts described above, large-area contacts 1843 made of a much stronger electrically conductive contact material are applied above or below it. These large-area contacts 1843 are designed in a narrow wedge shape, starting at one end point and extending to a wide section 1844. Better adjustment of the heating device 1811 is partly possible as a result.

[0103] Figure 30 also shows that in addition to the large-area contacts 1843, the connecting contacts 1816 of the two parallel strip-shaped heating electrical conductor assemblies 1814 are similarly designed with a central wide section that narrows towards the two ends, as can be seen, for example, in Figure 18. In this way, contact material can be saved, since less current is expected at the ends of the connecting contacts 1816 than in the wide central region.

Claims

1. A heating device having a large-area expanded carrier, two connection contacts, and at least one heating electrical conductor assembly on the carrier connected to the two connection contacts for electrical connection, the heating electrical conductor assembly has a plurality of heating electrical conductors; the heating electrical conductors are connected to each other at connection points; the heating electrical conductors are wired together to form parallel and series circuits between the two connection contacts; each set of at least three heating electrical conductors forms a closed mesh, and the at least three heating electrical conductors are connected to each other at a single connection point; the heating and electrical conductor assembly is applied on the carrier in a film configuration by a film method; the heating device has at least one additional heating electrical conductor assembly having two additional connection contacts and a single large-area additional heating electrical conductor disposed therebetween; the additional heating electrical conductor has a closed surface; an additional heating electrical conductor extending between the two additional connection contacts; A heating device, wherein the length of the additional heating electrical conductor is at least 10 times greater than its width.

2. 2. The heating device of claim 1, wherein at least 80% of the connection points have an equal number of heating electrical conductors connected to them.

3. 3. Heating device according to claim 1 or 2, characterized in that exactly three heating electrical conductors or exactly four heating electrical conductors are connected to each other at a single connection point.

4. 4. The heating device according to claim 1, wherein at least 80% of the heating electrical conductors extend linearly.

5. 4. The heating device according to claim 1, wherein at least 80% of the heating electrical conductor is curved.

6. 6. Heating device according to claim 1, characterized in that at least 80% of the heating electrical conductors have the same length.

7. 7. A heating device according to claim 1, wherein the angular region between two adjacent heating electrical conductors at the connection point is rounded with a radius of at least 2% of the maximum width of the heating electrical conductor.

8. 8. Heating device according to claim 1, characterized in that the heating electrical conductors are provided with different widths with a maximum variation of 40% of the width.

9. 9. The heating device of claim 8, wherein the width of the heating electrical conductor varies so as to have a constant width over the range between the two connection points at its ends.

10. 9. The heating device of claim 8, wherein the heating electrical conductor has a width that varies over the range between two connection points at its ends.

11. 11. Heating device according to any one of claims 1 to 10, characterized in that the film thickness of the heating electrical conductor or heating electrical conductor assembly varies by up to 10%.

12. 12. Heating device according to any one of claims 1 to 11, characterized in that in the edge region of the heating electrical conductor assembly recesses are provided in the edge region in the form of depressions.

13. 13. Heating device according to any one of the preceding claims, characterized in that the free surface area within the heating and electrical conductor assembly is free of heating and electrical conductors and connection points.

14. 14. Heating device according to any one of the preceding claims, characterized in that the surface heat output within the surface of the heating electrical conductor assembly varies by up to 25%.

15. A heating device as described in any one of claims 1 to 14, characterized in that the secondary connection contacts are connected to each of the connection contacts arranged in pairs facing each other in a direction perpendicular to the longitudinal extent of the connection contacts, and the secondary connection contacts each connected to the connection contacts are separated from each other and each are electrically connected to the connection contacts by a bridge contact.

16. 16. A heating device according to any one of claims 1 to 15, characterized in that a large-area contact is applied to the heating electrical conductor assembly, the large-area contact being designed in a strip and covering at least a part of the width of the heating electrical conductor assembly in a direction transverse to its longitudinal extent and making electrical contact.

17. 17. The heating device according to claim 1, wherein the width of the additional heating electrical conductor is smaller than the width of the heating electrical conductor.

18. 18. The heating device according to claim 1, wherein the length of the additional heating electrical conductor is 90 to 150% of the length of the heating electrical conductor.

19. 19. A heating device according to any one of claims 1 to 18, characterized in that at least two heating electrical conductor assemblies and at least two additional heating electrical conductor assemblies are arranged on a carrier, and two heating electrical conductor assemblies run between the two additional heating electrical conductor assemblies.

20. 20. A heating device according to any one of claims 1 to 19, characterized in that the mesh is designed approximately hexagonally or in the form of a honeycomb, in which in particular each of four longitudinal sides of the hexagon is formed by a single heating electrical conductor and two longitudinal sides of the hexagon are formed by one long connection point.

21. 21. The heating device according to claim 1, wherein an insulating and / or dielectric layer is provided between the heating electrical conductor and the carrier, the insulating and / or dielectric layer being at least as wide as the heating electrical conductor, being at most 10 mm wider than the heating electrical conductor on both sides thereof and projecting at most 10 mm below the heating electrical conductor on both sides, and the insulating and / or dielectric layer leaving free spaces within the mesh where there is no insulating and / or dielectric layer.

22. 22. A heating device according to any one of the preceding claims, characterized in that a cover layer is provided directly on or above the heating electrical conductor, the cover layer being at least as wide as the heating electrical conductor, being at most 10 mm wider than the heating electrical conductor on both sides and projecting at most 10 mm beyond the heating electrical conductor on both sides, and the cover layer leaving free space within the mesh where there is no cover layer.

23. 23. Heating device according to claim 1, characterized in that at least one connecting contact is designed as a grid structure.

24. 24. A heating device according to any one of claims 1 to 23, characterized in that the heating electrical conductor assembly or its heating electrical conductors are cut along free cutting areas, which separate the closing surfaces of the heating electrical conductor assembly, thereby cutting individual heating electrical conductors such that the closing surfaces are electrically separated and electrically insulated from the remainder of the heating electrical conductor assembly.

25. 25. A heating device according to any one of the preceding claims, characterized in that linear tracks of heating electrical conductor material are provided on the carrier below the grid-shaped heating electrical conductor assembly between the two connection contacts or directly above or above the grid-shaped heating electrical conductor assembly between the two connection contacts, transverse to the general direction of current flow.

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