EP3261409A1 - Method of manufacturing a heating device and heating device - Google Patents

Abstract

In a method for producing a heating device (11) with a planar heating conductor (17a, 17b), which is applied in a layered construction on a support (13), the electrical resistance of the heating conductor between terminal contacts (for electrical adjustment of the heating conductor to a predetermined value ( 21, 22) as power terminals for the heating conductor reduced by applying additional electrically conductive material. This can either be contact material (29) with which additional additional heating conductor surfaces (19a, 19b, 19b ') are connected in parallel to the heating conductor. Thereby, the electrical resistance can be reduced.

Description

The invention relates to a method for producing a heating device, in particular also for calibrating a heating device, and to a corresponding heating device.

Heating devices, in particular for household appliances and / or kitchen appliances or cooking appliances, are nowadays often realized with laminar heating elements in layered construction, in particular so-called thick-film heating elements or thick-film heating conductors. This enables good areal heating as well as the integration into modern, mass-produced and precise mass production processes. Frequently, the heating conductors are applied using areal application methods such as screen printing or inkjet. Precise heating power generation and controllability requirements, and compensation for manufacturing tolerances due to the deposition process, typically require balancing of the heating element or heating conductor to set it to an exact resistance value. For this purpose, a removal of heating conductor material can take place, in particular by connecting bridges, for example, by means of laser or areas of the heating conductor are cut and thus virtually deactivated. The disadvantage here is that the surface of the heating element or of the heating element, which should ultimately produce heating power, is reduced.

TASK AND SOLUTION

The invention has for its object to provide an aforementioned method and a heating device mentioned above, with which problems of the prior art can be solved and it is in particular possible to produce a heater or a heat conductor of this heater or equalize that no reduction of the heated and thus quasi-active surface of the heating element takes place.

This object is achieved by a method having the features of claim 1 and by a heating device with the features of claim 14. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features are described only for the process or only for the heater. However, they should apply independently and independently of each other for both the process and the heating device can. The wording of the claims is incorporated herein by express reference.

It is provided that the heating device has at least one planar heating conductor, which is applied in a layered construction on a support. In this case, the heating conductor is electrically connected to two connection contacts and, so to speak, mechanically, advantageously in that they overlap it and lie flat on it. These connection contacts form electrical power connections for the heating conductor. Advantageously, they are elongated.

To compensate for the resistance or for electrical adjustment of the resistance of the heating element to a predetermined value of its electrical resistance between the terminals as a power connection, this resistance is reduced by additionally electrically conductive material is applied. Unlike the above-mentioned known methods of the prior art alone can be achieved by just that no areas of the heat conductor are separated, deactivated or removed, but an addition occurs.

In a first basic embodiment of the invention, the heating conductor has a main heating conductor with a main heating conductor surface and at least one, advantageously two to five or even to eight additional heating conductor surfaces as additional heating conductor, which are each applied to the carrier. Advantageously, they are applied as separate surfaces and in a single or joint step. The at least one additional Heizleiterfläche is between 1% and 25% of the main Heizleiterfläche. Furthermore, the main heating conductor surface and the at least one additional heating conductor surface are advantageously connected to one another only at a single aforementioned first common electrical connection contact. By applying additional contact material, the additional Heizleiterfläche can be electrically connected or connected to this as a parallel connection to the main Heizleiterfläche. This increases thereby the electrically active and operable in heating surface of the heating element. This means that prior to the application of the additional contact material, the other opposite end of the additional heating conductor surface or the additional heating conductor surface per se is not electrically contacted or connected.

Simplified one can imagine an embodiment of the invention in this embodiment so that the at least one additional Heizleiterfläche in the initial state of the heater directly after the first step of the production or before a resistance balance while connected to the common terminal contact with the main Heizleiterfläche and at these is electrically connected, but is electrically or in respect of a heating effect is inactive because it is not connected to the second end. By additional contact material that forms either a total of a second terminal contact for the additional Heizleiterfläche or connects an existing second terminal contact with the second terminal contact of the main Heizleiterfläche, the additional Heizleiterfläche is also electrically connected. In this case, it is connected in particular parallel to the main heating conductor surface. Thus, an adjustment of the electrical resistance of the heater is possible by the electrical resistance is reduced by an additional parallel circuit, namely with the additional Heizleiterfläche. At the same time, however, the heated area increases by just the additional connected additional Heizleiterfläche. If the heater is operated at mains voltage, which is often so provided, so also increases the total generated heat output of the heater.

It should therefore be provided here that the application method or production method for the heating conductor with main conductor surface and additional heating conductor surface or several additional heating conductor surfaces is designed so that the electrical resistance is rather too large. In the case of the above-described adjustment, it can then, as it were, be gradually reduced by the proportionate resistance amounts of the additional heating conductor surfaces until the desired value is reached.

The additional electrically conductive material as contact material is advantageously used as a connection contact or as a power connection for further Heizleiterflächen, which have already been applied as additional Heizleiterflächen together with a main main Heizleiterfläche on a support, preferably in the same process step and in the same way and Wise. Electrically connected by means of connection contacts as power connections, however, only this main heating conductor surface is connected to one of the connection contacts and the at least one additional heating conductor surface is connected. But as long as it is not electrically connected at its other end via a further corresponding terminal contact as a power connection, it is not electrically effective, and this further connection is made precisely by the additionally applied contact material. Thus, at least one or even a plurality of additional heating conductor surfaces are connected to a main heating conductor surface in parallel, whereby the total electrical resistance of the heating device is reduced when the resistance value is adjusted.

It can be provided that at the end to be connected to the additional Heizleiterfläche already a connection contact is provided, to which the additional Heizleiterfläche is contacted by resting or overlapping. Then it may be sufficient if contact material with a length of a few millimeters is connected as a contact bridge of this existing terminal contact to an advantageously running in the vicinity of the terminal contact of the main Heizleiterfläche. Thus, a very good electrical contact between the terminal contact and additional heating conductor surface is achieved and the amount of contact conductor material to be applied can be very small.

Alternatively, it can be provided that the additionally applied contact conductor material first creates such a connection contact to at least one additional auxiliary heating conductor surface, wherein such a connection contact then extends directly from the additional heating conductor surface directly to a connection contact of the main heating conductor surface, as described above is.

The specific electrical resistance of the contact material may advantageously be much lower than that of the heating conductor material. It may be between 0.01% and 25% of the electrical resistance of the heating conductor material, preferably between 0.05% and 5%.

In an advantageous embodiment of the invention, it is possible that a plurality of additional Heizleiterflächen per main Heizleiterfläche are provided and they are of different sizes. Advantageously, all additional heating conductor surfaces are each of different size or no two additional heating conductor surfaces have the same size and thus the same electrical resistance. Thus, depending on the electrical resistance, which is to be added in the parallel parallel to the main Heizleiterfläche, from the several additional Heizleiterflächen exactly that single additional Heizleiterfläche or combination of additional Heizleiterflächen be selected, which then as well as possible in parallel gives the desired resistance value.

In a further advantageous embodiment of the invention can be provided that a length of the main Heizleiterfläche and the additional Heizleiterflächen is the same. Thus, the same application methods with the same resulting layer thickness, a uniform resistance distribution and thus also heating power generation can be achieved.

In principle, it is provided in the invention that, for the production of a heating device and in particular for a resistance adjustment of the heating device, the laminar heating conductor is applied in layered construction to the carrier. This is advantageous in itself a conventional thick-film process with a thick film paste commonly used for heating conductors. These can be applied in an advantageous and known manner, particularly advantageous by screen printing. On a support for the heating conductor connection contacts may be previously applied as power connections, but they are advantageous only subsequently applied to the finished heating element. For this purpose, an electrically conductive material is used as the contact material, as it is usually used for such terminals or power terminals or printed conductors on a support or a printed circuit board. It may be copper in a simple design with a prior application method according to a conventional printed circuit board method. Alternatively, the material can be subsequently printed in paste form, this paste then particularly advantageously contains a significant proportion of metal particles, in particular copper and / or silver.

In an advantageous embodiment of the invention it can be provided that additional heating conductor surfaces have a current flow direction which runs largely or completely at a right angle to the current flow direction of the main heating conductor surface. This is advantageous for all additional Heizleiterflächen.

On the one hand, while it is possible that additional Heizleiterflächen are distributed for a main Heizleiterfläche, so to speak some in an outer region or end portion of the main Heizleiterfläche and some in another outer region of the main Heizleiterfläche. As a result, it can be achieved that the additional heating conductor surfaces are more distributed and, in particular, when no additional heating conductor surface is connected or electrically activated in the case of resistance compensation, the non-heating surface regions which are then formed are better distributed. On the other hand, it can be provided that all additional heating conductor surfaces which serve to balance the resistance of a main heating conductor surface are grouped together or adjacent.

It is advantageously provided that the or each additional heating conductor surface at each end already has a connection contact as a power connection, advantageously a common connection contact connecting all of them. This connection contact is advantageously connected to a connection contact of the main heating conductor surface. Particularly advantageously, the individual additional Heizleiterflächen are already provided at its other end with connection contacts, which are not connected to each other and are not connected to a terminal contact of the main Heizleiterfläche or with the main Heizleiterfläche itself.

In an embodiment of the invention can be provided that the non-interconnected terminal contacts of the additional Heizleiterflächen at a small distance, advantageously 0.5 mm to 3 mm, have a past and parallel connection terminal, which already electrically connected to the terminal contact of the main Heizleiterfläche connected is. In order then in each case to connect an additional heating conductor surface in the resistance compensation parallel to the main heating conductor surface, it is sufficient to connect the short free connection contact of the desired additional heating conductor surface with the passing connection contact with applied electrically conductive material, in particular contact material. So any electrical connection of individual desired additional Heizleiterflächen can be achieved. Furthermore, in this second or subsequent method of applying contact material, not so much contact material has to be applied, which increases process reliability.

In a second basic embodiment of the invention, the additionally applied electrically conductive material can be heat conductor material, as has already been used for the production of the main heat conductor. It can silver, graphite or the like. as a conductive material. The application method is advantageously also a thick-film process or an inkjet process. This Heizleitermaterial is applied to the existing heating element and thus increases at least partially its thickness. Advantageously, it is provided that the additional application of Heizleiterermaterial takes place with an area on the already existing heating element, which is considerably less than the entire Heizleiterfläche, wherein it is advantageously only 5% to 20%. Particularly advantageously, the additional Heizleitermaterial is applied even with a single severed heating conductor as a single contiguous area and not in the form of several, separate areas. An application of the additional Heizleitermaterials is preferably carried out in strip form or as a strip per heat conductor.

The contact material can be advantageously separated by an insulating gap from the other terminal contact of the main Heizleiterfläche or other additional Heizleiterflächen, in particular an insulating gap between 0.1 mm and 5 mm wide, more preferably between 0.5 mm and 2 mm. By a small insulating gap can be done a denser occupancy of the carrier.

Similarly, an insulating gap between the contact material and the additional heating conductor surfaces may be provided, which is in particular between 0.1 mm and 5 mm or between 0.5 mm and 2 mm wide.

Finally, it is also possible to provide insulation gaps between the main heating conductor surface and additional heating conductor surface. These insulation gaps can be in the range between 0.1 mm and 5 mm wide, advantageously between 0.5 mm and 2 mm.

The additional Heizleitermaterial can be applied with always the same thickness, but with different large area expansion on the existing heating element or its Heizleiterfläche. By varying the area, the reduction of the total electrical resistance during adjustment can then be set to a predetermined value. For this purpose, the surface, which is advantageously a rectangular surface or a strip, can be varied in length and / or width. Such an additional heating conductor material particularly advantageously extends on the heating conductor surface over an entire extent of the heating conductor surface in one direction, advantageously in a direction transverse to the direction of current flow between the connection contacts or power terminals of the heating conductor. Thus, the behavior of the current flow between the two terminals is always the same. To vary a surface of the additionally applied Heizleitermaterials then only one change in one dimension, that is to say the width or along the current flow, made, but this is considered sufficient.

Alternatively, the thickness can vary with an always identical and predetermined area or surface geometry of the additionally applied heating conductor material. In this case, a thickness of the applied Heizleitermaterials should always be about the same, but can be varied overall, which of course the entire electrical resistance of the heating element can be changed and, depending on the thickness, can be reduced.

These and other features will become apparent from the claims and from the description and drawings, wherein the individual features in each case alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections and intermediate headings does not limit the statements made thereunder in their generality.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine Draufsicht auf eine erste Ausgestaltung einer Heizeinrichtung gemäß einem ersten grundsätzlichen Aspekt der Erfindung mit zu Haupt-Heizleitern durch Brücken parallel anschließbaren Zusatz-Heizleitern,

Fig. 2

eine Vergrößerung eines Ausschnitts der Heizeinrichtung der Fig. 1,

Fig. 3

eine Draufsicht auf eine zweite Ausgestaltung einer Heizeinrichtung ähnlich derjenigen aus Fig. 1 mit einem etwas anders ausgebildeten elektrischen Anschluss an die Zusatz-Heizleiter,

Fig. 4

eine Vergrößerung eines Ausschnitts der Heizeinrichtung der Fig. 3,

Fig. 5

eine Draufsicht auf eine dritte Ausgestaltung einer Heizeinrichtung mit anders ausgerichteten und ausgebildeten Zusatz-Heizleitern,

Fig. 6

eine Vergrößerung auf einen Teil der Heizeinrichtung der Fig. 5 mit durch eine Brücke angeschlossenem Zusatz-Heizleiter,

Fig. 7

eine Vergrößerung ähnlich Fig. 6 mit einem größeren durch eine Brücke angeschlossenen Zusatz-Heizleiter,

Fig. 8

eine Draufsicht auf eine vierte Ausgestaltung einer Heizeinrichtung ähnlich derjenigen der Fig. 5 mit voneinander getrennten Zusatz-Heizleitern,

Fig. 9

eine Draufsicht auf eine weitere Heizeinrichtung gemäß einem zweiten grundsätzlichen Aspekt der Erfindung mit zusätzlich auf die Heizleiter aufgebrachtem Heizleitermaterial in Streifenform und

Fig. 10

einen Schnitt durch die Heizeinrichtung der Fig. 9.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

Fig. 1

a plan view of a first embodiment of a heater according to a first basic aspect of the invention with parallel to main heat conductors by bridges parallel additional heating conductors,

Fig. 2

an enlargement of a section of the heater of Fig. 1 .

Fig. 3

a plan view of a second embodiment of a heater similar to that of Fig. 1 with a slightly different electrical connection to the additional heating conductors,

Fig. 4

an enlargement of a section of the heater of Fig. 3 .

Fig. 5

a top view of a third embodiment of a heater with differently oriented and trained additional heating conductors,

Fig. 6

an enlargement to a part of the heater Fig. 5 with additional heating conductor connected by a bridge,

Fig. 7

similar to a magnification Fig. 6 with a larger additional heating conductor connected by a bridge,

Fig. 8

a plan view of a fourth embodiment of a heater similar to that of Fig. 5 with separate additional heating conductors,

Fig. 9

a plan view of a further heating device according to a second basic aspect of the invention with additionally applied to the heat conductor Heizleiterermaterial in strip form and

Fig. 10

a section through the heater of Fig. 9 ,

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the Fig. 1 is a plan view of a heater 11 is shown, which is basically similar to that in the German patent application DE 102016209012.7 filing date of 24 May 2016 with the same applicant. In this respect, reference is also made to this patent application for further explanations and with regard to feasibility.

The heating device 11 has a flat elongate support 13. This can consist of a flat substrate made of ceramic or partially insulated metal. Alternatively, it could also be a rolled-up representation of a short tube piece with the circumference corresponding to the length of the carrier 13 and a length corresponding to the height of the carrier 13th

Links to the heater 11, a connection pad 15 is provided, as is customary per se and does not need to be explained in detail. Mainly, the heater 11 and the carrier 13, a left heat conductor 17a and a right heat conductor 17b, respectively, the main heat conductor surfaces form. They consist of a corresponding Heizleitermaterial, as has been previously mentioned, which has been applied as a thick-film heating conductor in a conventional thick-film process on the carrier 13 or on an insulating layer. Advantageously, here is a screen printing process, but also inkjet process or other application methods are possible. After application, a conventional thermal after-treatment is carried out as a so-called baking of the heating conductors 17a and 17b.

In addition to the heating conductors 17a and 17b and advantageously in the same process step and thus also with the same thickness and the same physical and electrical specific properties, three narrow additional heating conductors 19a, 19b and 19b 'are applied with the same length. The distance between the heating conductors and the additional heating conductors can essentially correspond to that of the aforementioned insulating gaps. They have also been branded. The width of the additional heating conductors 19a, 19b and 19b 'is here in each case different in order to illustrate different possibilities. In practice, they should be the same for both heating conductors or both main heating conductor surfaces 17.

At the top of the heating conductors 17a and 17b and the additional heating conductors 19a, 19b and 19b 'runs a common straight terminal contact 21. This is made of a previously mentioned contact material, for example, printed in principle the same way, but here on the corresponding Heating conductor or on the finished Heizleiterermaterial. In a subsequent firing of the terminal 21, a good electrical connection is made. This is generally known from thick film processes.

At the bottom, a connection contact 22a is applied to the heating conductor 17a, and a connection contact 22b is applied to the heating conductor 17b. These connection contacts 22a and 22b are guided by means of conductor tracks 25 to the connection pad 15.

At the bottom of the additional heating conductor 19a, an additional connection contact 23a is printed thereon in a corresponding manner with a gap 27a as the aforementioned insulating gap to the connection contact 22a. In a corresponding form, additional connection contacts 23b and 23b 'are printed on the lower side of the additional heating conductors 19b and 19b', which likewise have gaps 27b and 27b 'as insulation gaps. Thus, the heating conductors and the respective terminal contacts in their own process sections, but then all together and applied in the same manner. The electrical connection can be seen, the heating conductors 17a and 17b are connected in series. The auxiliary heating conductor 19a can be connected in parallel to the heating conductor 17a as the main heating conductor surface by bridging the gap 27a. Similarly, the auxiliary heating conductors 19b and 19b 'may be connected in parallel with the heating conductor 17b as the main heating conductor surface by bridging the gaps 27b and 27b'.

To bridge the gap 27b, as shown in the Fig. 2 for the auxiliary heating conductor 19b of the heating conductor 17b, a bridge 29b of contact material may be applied across the gap 27b. This is advantageously carried out in a state of the heating device 11, if usually a resistance compensation for the heating conductor 17b or this main heating conductor surface is made. This means that both the heating conductor material and the contact material for the connection contacts 21 and 22 are baked. By measuring the electrical resistance of the heating conductor 17b whose deviation can be detected by a desired value, which, as has been explained above, the resistance tends to be made too large and can be reduced by connecting additional heating conductors or additional Heizleiterflächen. If it is considered sufficient to switch only the additional heating conductor 19b parallel to the heating conductor 17b, the application of the bridge 29b over the gap 27b is sufficient. The resistance values of the additional heating conductors 19b and 19b 'are known, but may alternatively still be detected prior to performing the resistance adjustment.

Under certain circumstances, the deviation from the desired value is still so great that even the additional heating conductor 19b 'must be connected in parallel as a further additional heating conductor surface. Then in the same method step, in addition to the bridge 29b, another bridge over the gap 27b is advantageously applied or dispensed over the gap 27b '. This is not shown here, but is very easy to imagine. Advantageously, the bridges 29 are applied with a similar width and thickness as the terminal contacts and additional connection contacts. After applying one or more bridges, in turn, a firing of the respective applied additional contact material is performed.

Even if the heating conductors 17a and 17b have been applied as main heating conductor surfaces in the same method step and usually with the same thickness, their electrical resistances may deviate from one another so that they advantageously have to be adjusted individually or differently.

In the Fig. 3 For example, a heater 111 is similar to that of FIG Fig. 1 represented with a carrier 113 and a connection pad 115, on which in turn two heating conductors 117a and 117b are applied as main heating conductor surfaces. The left heat conductor 117 a is as large as in the Fig. 1 , the right heat conductor 117b slightly smaller. In practice, they should and should be the same size and, above all, identical. However, it should be shown here how a plurality of, namely three, additional heating conductors 119b, 119b 'and 119b "can be provided as additional heating conductor surfaces for resistance compensation for a heating conductor as the main heating conductor surface.

At the top of the heating conductors 117a and 117b again runs a common connection contact 121. Down at the heating conductor 117b extends another terminal contact 122b, which is pulled in the right end with an end portion 122b 'something down. Thus, it can run past lower additional connection contacts 123b, 123b 'and 123b "of the additional heating conductor at a small distance, for example 1 mm to 3 mm of the Fig. 4 to see. After measuring the electrical resistance of the heating conductor 117b as the main heating conductor surface, the electrical resistance to be switched in parallel can be determined in order to achieve the desired value. Then the one or those are selected from the three differently wide additional heat conductors 119b, 119b 'and 119b ", which then, after parallel connection, yield the desired resistance value as a final value." For this bridges 129b, 129b' and / or 129b ", as shown in dashed lines are applied as needed for an electrical connection. The special configuration of the connection contact 122b with the end region 122b 'thus makes it possible, deviating from the illustration of FIG Fig. 1 and 2 in that it is not compulsory to first always switch that additional heating conductor surface parallel to the main heating conductor surface which is closest thereto, but one or more arbitrary ones. The widths of the additional heating conductors 119b, 119b 'and 119b "should be selected so that they allow the greatest possible variability of the connection of different combinations.

In the Fig. 5 In plan view, a heating device 211 is shown with a carrier 213, which has only a single heating conductor 217 as the main heating conductor surface. Connection fields or the like are not shown here for simplicity. As with the other heaters 11 and 111 Here, the direction of the current flow through the heating conductor 217 from bottom to top, ie perpendicular to an upper terminal contact 221 and a lower terminal contact 222. For a resistance adjustment of the heating element 217 is in a right area of the upper terminal contact 221 pulled to the right and then it bends at right angles down from. Here, a substantially square field is applied as additional heating conductor 219, which overlaps in its right end region of the terminal contact 221 and is thus electrically contacted.

Four additional connection contacts 223, 223 ', 223 "and 223'" are provided, which are all the same length, but this is not necessarily so. They have been applied from contact material to the auxiliary heating conductor 219, similar to that described for the other embodiments. They are separated by gaps 227 ', 227 "and 227'", respectively. It should be noted, however, that the surface of the additional heating conductor 219 nevertheless passes through. The lower connection contact 222 is electrically separated by a gap 227 from the additional heating conductor 219 and the lowest additional connection contact 223, respectively.

So if, as in Fig. 6 is shown in the magnification, it is recognized in the resistance balance that at least by means of a bridge 229 the lowest additional terminal contact 223 must be connected, so must be connected in parallel to the heating element 217, so there is a current flow, although substantially perpendicular to that in the Heating conductor 217 is. This is indicated by the arrows. The dashed area with the dashed curve shows, however, that the current flow between the left of the additional terminal contact 223 and right the terminal contact 221 is not limited to a constant width, but the current flow to the right, so to speak expands in terms of area, which is easy to imagine. Consequently, the direction of the current flow varies on the one hand, and of course the surface heating power also varies on the other hand, it becomes smaller to the right due to the increased width of the energized region and thus of the corresponding cross section.

Another option is according to Fig. 7 shown, as in the resistance adjustment and the bottom two additional terminal contacts 223 and 223 'are electrically connected by means of a longer bridge 229 and connected to the terminal contact 222, when a greater reduction is required than at Fig. 6 , Again, then, as described above, represented by the dashed curve shown an additional electrically traversed additional Heizleiterfläche 219 with varying or increasing to the right width. Again, the current flow is indicated by arrows and fans out, so to speak.

In order to achieve a defined current flow in the additional heating conductor surfaces, in particular with a constant surface heating power, a heating device 311 according to FIG Fig. 8 be educated. To the right of a heating conductor 317 as the main heating conductor surface with an upper connection contact 321 and a lower connection contact 322, four strip-like additional heating conductors 319, 319 ', 319 "and 319'" are shown. They are all the same width and all the same length, in particular, they are just as long as the heat conductor 317 between the terminals 321 and 322nd So is the respective Flächenheizleistung the same for parallel connection.

On the right all additional heating conductors are overlapped by the connection contact 321. On the left, they each have an auxiliary terminal contact 323, 323 ', 323 "and 323' '', which are formed and manufactured as described above By bridging one or more of the gaps 327, 327 ', 327" and 327' " An electrical connection can take place or the additional heating conductors can be gradually additionally connected in parallel to the heating conductor 317 as the main heating conductor surface.

Here is also easy a modification of the heater Fig. 8 according to those from the 3 and 4 conceivable with an end portion of the terminal contact 322, which is pulled in the area to the right of the heating element 317 at a distance from this and the additional heating conductors 319 upwards, wherein it also runs past the additional connection contacts 323 at a small distance. The additional heating conductor surfaces have different widths. Then, by means of corresponding short bridges, those additional heating conductors 319 as additional heating conductor surfaces can be electrically connected, which together give the exactly desired reduction of the resistance of the heating conductor 317 during the adjustment, so that a total of a predetermined value of the electrical resistance for the heating conductor 317 is achieved becomes.

In the Fig. 9 Although another second embodiment of the invention is shown in principle, in which a resistance balance is indeed carried out by the application of additional electrically conductive material. Unlike in the embodiments before but no contact material is applied to electrically connect additional Heizleiterflächen as additional heating conductor and thus to activate, so that they reduce the resistance and support the heating operation. Instead, heating conductor material is additionally applied here to a heat conductor surface and only in regions. A heater 411 is formed substantially similar to that in FIG Fig. 1 shown with a support 413 and a connection pad 415, on which two heating conductors 417a and 417b are applied. These are here different lengths between the terminals 421 on the one hand and 422a and 422b on the other. But this does not have to be so, they could also according to the Fig. 1 be the same length through a slightly different terminal contact 422b. The heating conductors 417a and 417b and the connection contacts are applied as described above. The order could also be different here, so that first the connection contacts are applied to the carrier 413 and then the heating conductors 417. This does not matter here.

After completing the heating conductors 417a and 417b, their electrical resistance is measured and compared with a desired value. Here, the application method for the heating conductor 417 is also designed here so that the electrical resistance is always rather too large or is never too small. In order to then reduce the resistance value, heating conductor material can be applied to the heating conductors 417a and 417b in the respectively required degree. This is done, as exemplified here, in strip form as a strip-shaped additional Heizleitermaterial 431 a and 431 b. As seen from the sectional view of Fig. 10 it can be seen, the additional Heizleitermaterial 431 b on the heating conductor 417b and here forms, so to speak, a local parallel circuit or thickening. Thus, the electrical resistance is lower in this area and thus the total electrical resistance lower. Depending on the desired value and actual value for the heating conductor 417b, the lateral extent of the additional heating conductor material 431 b in Fig. 10 be adapted, ie the length of the additional Heizleiterermaterials in the current flow direction according to Fig. 9 between the connection contacts. A thickness of the additional Heizleitermaterials should always remain the same, so that it is possible to apply the additional Heizleitermaterial for the two heating conductors 417a and 417b in the same process, just with each possibly another area.

Like from the FIGS. 9 and 10 is easy to see, the additional Heizleitermaterial 431 should be located approximately in the middle, advantageously exactly in the middle, between the terminal contacts 421 and 422a and 422b, respectively, to achieve an approximately uniform distribution of the surface heating power. In fact, it can easily be seen that in the area of the additional heating conductor material 431b the surface heating power drops correspondingly.

Alternatively, in principle, the area with which the additional heating conductor material 431 is applied to the heating conductors 417 could also be the same in each case and vary in thickness, in order in each case to carry out an exact resistance compensation. Then it could be provided, in particular in a screen printing method with application of the additional Heizleitermaterials in several passes, for example, three to ten passes to vary the thickness by specifying the number of passes. Thus, in a screen printing process could always the same mask may be used for a consistent area of the additional heater material, only the number of passes for application would then vary. It could also be different in particular with two adjacent heating conductors 417.

While with the heaters the Fig. 1 to 8 additional Heizleiterfläche has been added to the resistance balance, which is already present in the manufacture of the heater before the adjustment, it remains in the second basic embodiment of the invention according to the FIGS. 9 and 10 equal. Here, however, it can already be selected to a maximum, so that the carrier 413 is, so to speak, maximally occupied, except for a connecting field 415 or the like. The heated area thus does not depend on the result of the resistance compensation. If, in the first basic embodiment of the invention, no resistance compensation may be necessary, then all additional heating conductors are not electrically active and, as it were, part of the surface of the carrier is not used for heating purposes, which would be possible in itself.

Claims (14)

Method for producing a heating device (11, 111, 211, 311, 411) with a planar heating conductor (17, 117, 217, 317, 417), which is applied in a layered construction to a carrier (13, 113, 213, 313, 413) is and the terminal contacts (21, 22, 121, 122, 221, 222, 321, 322, 421, 422) as power terminals for the heating conductor, characterized by the step that for electrical adjustment of the heating conductor to a predetermined value of the electrical resistance of the heat conductor between the terminal contacts (21, 22, 121, 122, 221, 222, 321, 322, 421, 422) is reduced by applying additional electrically conductive material (29, 129, 431). A method according to claim 1, characterized in that the additional electrically conductive material is contact material (29, 129, 229), as it is for connection contacts, conductor tracks or the like. on the support (13, 113, 213, 313) is used, wherein two connection contacts (21, 22, 121, 122, 221, 222, 321, 322) as electrical power connections for the heating conductor (17, 117, 217, 317) are provided, wherein the heating conductor with a main Heizleiterfläche and at least one additional Heizleiterfläche (19, 119, 219, 319) is applied to the carrier, wherein the main Heizleiterfläche and the additional Heizleiterfläche only at a first common terminal contact (21 , 121, 221, 321) are electrically connected to each other, wherein by applying additional contact material (29, 129, 229) the additional Heizleiterfläche is electrically connected to the other terminal contact as a parallel connection to the main Heizleiterfläche with enlargement of the electrically active and heating operation operable total area of the heating conductor. A method according to claim 2, characterized in that the at least one additional heating conductor surface (19, 119, 219, 319) between 1% and 25%, preferably between 3% and 15%, of the surface of the main heating conductor surface (17, 117, 217, 317). A method according to claim 2 or 3, characterized in that the at least one additional Heizleiterfläche (19, 119) has a current flow direction which is parallel to the current flow direction of the main Heizleiterfläche (17, 117), preferably all additional Heizleiterflächen to a Heating conductor, in particular the entire heating device (11, 111), have the same direction of current flow. A method according to claim 2 or 3, characterized in that the at least one additional Heizleiterfläche (219, 319) has a current flow direction which is perpendicular to the current flow direction of the main Heizleiterfläche (217, 317), preferably all additional Heizleiterflächen to a Heating conductor, in particular the entire heating device (211, 311), the same direction of current flow. Method according to one of claims 2 to 5, characterized in that between one and eight additional Heizleiterflächen (19, 119, 219, 319) per main Heizleiterfläche (17, 117, 217, 317) are provided. Method according to one of claims 2 to 6, characterized in that at least two additional Heizleiterflächen (19, 119, 219, 319) are provided and they have a different width, preferably all additional Heizleiterflächen, parallel to a main Heizleiterfläche (17, 117, 217, 317) are connected, have the same length between the connection contacts (21, 22, 121, 122, 221, 222, 321, 322), in particular all additional heating conductor surfaces of a heating device (11, 111, 211, 311) , Method according to one of claims 2 to 7, characterized in that on an end portion of the additional heating conductor surface (119) opposite the common terminal contact (121) with the main heating conductor surface (117) contact material (123) over at least part of the width of Endbereich the additional Heizleiterfläche is applied, preferably over the entire width of the end portion, said contact material (123) by an insulating gap from the further terminal contact (122, 122 ') of the main Heizleiterfläche (117) or other additional Heizleiterflächen is separated in particular, the insulating gap between 0.1 mm and 5 mm wide. A method according to claim 8, characterized in that the further connection contact (122) of the main Heizleiterfläche with a connection region (122 ') separated by an insulating gap on the contact material (123) of the additional Heizleiterflächen (119) passes, in particular the Isolierlücke between 0.1 mm and 5 mm wide, wherein preferably the further connection contact (122) of the main heating conductor surface with the connection region (122 ') runs past all additional heating conductor surfaces (119) which can be connected in parallel with it. Method according to one of the preceding claims, characterized in that first heating conductor material for the heating conductor (17, 117, 217, 317, 417) on the carrier (13, 113, 213, 313, 41) is applied, and then contact material for the connection contacts (21, 22, 121, 122, 221, 222, 321, 322, 421, 422) is applied as electrical power terminals at least partially on the heating conductor. Method according to one of the preceding claims, characterized in that Heizleitermaterial, as it has been used for the production of the heating conductor (417) is applied as an additional electrically conductive material (431) on a Heizleiterfläche (417), wherein preferably the Heizleitermaterial as additional electric conductive material is applied in a direction transverse to the direction of current flow strip-like on the Heizleiterfläche. A method according to claim 11, characterized in that the Heizleitermaterial (431) is applied with a length corresponding to the dimension of the heating conductor (417) in the measuring direction parallel between the terminal contacts (421, 422) or in the measuring direction transverse to the current flow direction. Method according to one of the preceding claims, characterized in that the electrical resistivity of the contact material (21, 22, 29, 121, 122, 129, 221, 222, 229, 321, 322, 421, 422) is between 0.01% and 25% of the electrical resistance of the Heizleitermaterials, preferably between 0.05% and 5%. Heating device produced by a method according to one of the preceding claims, characterized in that the heating device (11, 111, 211, 311, 411) has a carrier (13, 113, 213, 313, 413) and at least one heating conductor (17, 117 , 217, 317, 417) with connection contacts (21, 22, 121, 122, 221, 222, 321, 322, 421, 422) as power connections for the heating conductor.

Images