EP4398680A1 - Translucent flat heating element - Google Patents

Abstract

The invention relates to a surface heating element (1) with a transparent or translucent substrate (10), which forms a front side of the surface heating element (1) and which defines a flat, curved or multi-dimensionally shaped heating surface (11), and at least one sensor (21), wherein at least one heating element (12) is arranged in or on the substrate (10), which has at least one conductor track as a heating track (13) for electrically heating the substrate (10), wherein the at least one sensor (21) is arranged outside the heating surface (11) and is designed to determine the temperature and/or the functionality of the at least one heating element (12) and/or the heating surface (11).

Description

The invention relates to a surface heating element with a transparent or translucent substrate on which a heating surface is defined, and at least one sensor, wherein the sensor is arranged outside the heating surface.

Since the waste heat generated by the combustion engines is eliminated, especially in electric vehicles, and can therefore no longer be used to heat the interior, the use of electric surface heating elements is often provided for in such vehicles - but also in other applications.

From the state of the art and, for example, from the documents DE 203 19 024 U1 , EN 10 2007 055 015 A1 , EP 1 653 780 A1 and WO 2005/055660 A2 Various surface heating elements are known, each of which is provided with an opaque heating surface. The arrangement of the heating elements for heating the respective heating surface and the sensors for monitoring their function is essentially irrelevant as long as the desired function is fulfilled, since neither the heating element nor the sensors are visible to an observer from the intended viewing or front side of the respective surface heating element.

Especially in modern electric vehicles, such surface heating elements are also intended to be used as functional and/or design carriers, which accordingly provide additional functions in addition to heating the vehicle interior.

If, for example, a surface heating element is to be combined with a display surface or with lighting, the problem is that the heating element and/or the sensor may be visible and thus disturb the aesthetic sensibility of the viewer.

In this regard, Scripture suggests WO 2012/066112 A1 a surface heating element in which transparent heating current paths or heating tracks and transparent measuring current paths, which together with a measuring device form a sensor for temperature monitoring, are applied to a transparent substrate so that the substrate can be illuminated by a light source. The problem here is that the heating current paths and measuring current paths can themselves be transparent, but this does not make them invisible and can still be visible. Furthermore, the existing measuring current paths lead to a fragmentation of the heating surface heated by the heating current paths, so that homogeneous heating is no longer possible.

The invention is therefore based on the object of overcoming the aforementioned disadvantages and of providing a surface heating element that is as evenly translucent as possible with largely "invisible" functional elements which simultaneously enables homogeneous heating and function or temperature monitoring.

This object is achieved by the combination of features according to patent claim 1.

According to the invention, a surface heating element with a transparent or translucent substrate is therefore proposed. The substrate forms a front side of the surface heating element and defines a flat, curved or multi-dimensionally shaped heating surface on the front side, which is also transparent or translucent due to the transparency or translucency of the substrate. The front side can also be understood as a side of the surface heating element facing an interior. If the front side remains free of additional layers, the front side of the surface heating element is immediately visible to an observer and can be referred to as the visible side. The heating surface does not have to correspond to the entire front surface or surface of the substrate. The surface heating element also has a sensor for determining or detecting the temperature and/or functionality. In the substrate or preferably on the back, i.e. on the back of the substrate facing away from the front side, at least one heating element is also arranged, which has at least one conductor track as a heating track for electrically heating the substrate. It is essential that the at least one sensor is arranged outside the heating surface and is designed to determine the temperature and/or the functionality of the at least one heating element and/or the heating surface.

Because the sensor itself is not located in the heating surface or in an area of the substrate behind the heating surface, the latter is not dissected by the sensor, so that the heating tracks do not touch the heating surface. can be heated homogeneously. At the same time, the sensor is not visible through the substrate in the area of the heating surface.

Although known to the person skilled in the art, it should be additionally pointed out that translucency is understood to mean partial light transmission (of the substrate), whereas transparency is understood to mean image or visual transmission (of the substrate), so that, for example, a light source arranged behind the substrate illuminates the substrate in both cases, but a design surface with applied patterns is (clearly) recognizable and visible through the substrate, particularly in the case of a transparent substrate.

In summary, one of the core ideas of the invention is to increase the transparency or translucency of the substrate in the area of the heating surface by reducing the degree of coverage of the substrate of the heating surface, which is achieved by no longer arranging the necessary sensors for function or temperature monitoring in the area of the heating surface, but outside it.

The arrangement of at least one sensor outside the heating surface leads to several advantageous effects. The basic principle here is that the heating surface or its heating is no longer interrupted or broken up by the sensors or the supply lines required for the sensors, so that both the heating by the heating tracks and the translucency or transparency/translucency of the substrate in the area of the heating surface become more homogeneous or are less disturbed.

A sensor can basically consist of a measuring sensor and an evaluation unit. If several sensors are provided, these can also be formed by a measuring sensor and a common evaluation unit.

It is preferably provided that the at least one sensor, viewed from the front, is arranged adjacent to the heating surface and/or the substrate.

Furthermore, the transparency or translucency and generally the translucency of the substrate and in particular of a composite formed from the substrate, the at least one heating element and the at least one sensor can be improved in the region of the heating surface by reducing the degree of coverage or overlap of the substrate by the at least one heating element or the at least one heating track as much as possible.

This can be achieved on the one hand by the fact that the at least one heating element and the at least one heating track formed by it cover the substrate and/or the heating surface determined by the substrate by 1% to 30%, in particular by 10% to 20%, according to an advantageous further development.

Furthermore, it can be provided that the at least one heating track is as thin as possible and in particular 0.1 to 0.4 mm, further in particular 0.2 to 0.3 mm wide.

In addition, according to an advantageous development, the at least one heating track can cover the heating surface homogeneously, i.e. evenly. For this purpose, the at least one heating track can extend over the heating surface, for example, at regular intervals and/or in a meandering shape.

It can also be provided, for example, that in a (random) partial area of the heating surface of, for example, 10% of the heating surface, a deviation of the degree of coverage from any other (equal-sized) partial area of the heating surface of less than 10%, in particular 5%, further in particular 2% is provided.

The at least one heating track can, for example, consist of an electrically conductive material such as graphite, carbon, silver, copper, gold, aluminum or molybdenum as well as electrically conductive metal alloys. However, a variant in which the at least one heating track is made of an electrically conductive and at the same time transparent and/or translucent or non-transparent material is particularly advantageous. Transparent, conductive oxides (TCO), for example, can be considered for this.

Furthermore, the heating element can also have two supply lines for supplying power to the at least one heating track in particular. The supply lines can also be made of an electrically conductive material, such as silver, copper, gold, aluminum or molybdenum, as well as electrically conductive metal alloys. In a variant with such supply lines, it is provided that the supply lines are spaced apart from one another and, viewed from the front, are arranged on or in an edge region that surrounds the substrate and/or the heating surface in a frame-like manner, i.e. on (or in) the substrate but outside the heating surface or adjacent to the substrate but still outside the heating surface. Furthermore, the at least one heating track connects the two supply lines in an electrically conductive manner, so that a heating current flows or can flow between the supply lines via the at least one heating track.

Since the supply lines themselves are located outside the heating surface, the supply lines, which are preferably wider than the at least one heating track, can be formed from an opaque electrically conductive material.

The heating element and/or its at least one heating track and/or the supply lines are preferably applied to the substrate by printing.

In order to provide additional, inexpensive and effective function and/or temperature monitoring In order to enable this, a likewise advantageous variant provides that the at least one sensor is thermally and preferably not electrically contacted with the at least one heating element and in particular with its at least one heating track and is designed to determine the functionality and/or the temperature via the thermal contact.

The thermal contact or thermal connection between the sensor and the heating element or its heating track can be established via a thermally conductive material applied to the substrate or via the substrate itself.

Furthermore, the sensor can also be electrically contacted with the at least one heating element and designed to determine the functionality via a power consumption of the heating element measured by the sensor.

Furthermore, the temperature can be determined by the sensor via the voltage applied to the heating element or its at least one heating track, which is connected to the at least one heating element so as to allow a corresponding voltage tap or voltage detection.

If the sensor detects the temperature, the functionality can be determined from the temperature.

It can also be provided that the functionality is determined, for example, by comparing a temperature distribution on the heating surface recorded by the at least one sensor with a reference temperature distribution, whereby the reference temperature distribution for different operating states can be stored in the sensor or simulated by the sensor. Furthermore, the The reference temperature distribution may also correspond to the temperature distribution on a real surface heating element, for example one adjacent to an arrangement of several surface heating elements, which thus represents a reference surface heating element.

The temperature distribution or reference temperature distribution can be understood as, for example, the temperatures at several sensors, whereby the arrangement of the respective sensor in relation to the heating surface is known, whereby the temperatures of the heating surface or at the heating surface are known or at least determinable.

Since the at least one sensor is arranged outside the heating surface, it is no longer necessary for it to be arranged directly on the substrate. For example, it can be provided that the surface heating element also has a sensor carrier on, at or in which the at least one sensor is arranged. The sensor carrier runs around the substrate at least in sections in the form of a frame. Accordingly, the sensor carrier is provided on at least one side of the substrate or on two opposite sides of the substrate, for example, when viewed from the front, but can also enclose it on all four sides. Furthermore, the sensor carrier does not have to be transparent or translucent like the substrate, but can be non-transparent.

Furthermore, the sensor carrier and the substrate can be formed integrally with each other or can be integrally and in particular integrally connected to each other.

Furthermore, the substrate and/or the sensor carrier can be made of a flexible material and/or connected to one another via a flexible connector. This means that at least the sensor carrier can be moved or turned over from a plane with the substrate.

If a surface heating element with a sensor carrier is integrated into a decorative element, for example, the surface heating element can be applied to the front side of a design carrier, which may be backlit by a light source, and the sensor carrier can be folded over to the back of the design carrier so that the substrate is arranged on the front side and the sensor carrier on the back side of the design carrier.

The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

Fig. 1

eine erste Variante eines Flächenheizelements;

Fig. 2

eine zweite Variante eines Flächenheizelements.

Other advantageous developments of the invention are characterized in the subclaims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. They show:

Fig.1

a first variant of a surface heating element;

Fig.2

a second variant of a surface heating element.

The figures are exemplary schematics and show two similar but not identical variants of a surface heating element 1 from a visible or front view. The same reference numerals in the figures indicate the same functional and/or structural features.

Both for the surface heating element 1 of the Figure 1 as well as for the surface heating element 1 of the Figure 2 It applies that they have a transparent substrate 10, which is therefore clear and transparent, so that a design carrier arranged behind it, if applicable, with its design surface is visible and the substrate can be illuminated by a light source, if applicable.

The visibility of such a design surface and/or the translucence of a light source on the surface heating element 1 maximized or a disturbance/deterioration of the visibility on such a design surface or the translucency minimized and at the same time a heating in particular of a vehicle interior can be enabled or a heating of the heating surface 11 can be homogenized.

For this purpose, it is provided that a heating surface 11 is determined by the substrate 10 of the respective surface heating element 1, wherein only one or more heating elements 12 are provided in the area of the heating surface 11 and sensors 21 for temperature or function monitoring are arranged outside the heating surface 11.

In this case, the surface heating elements 1 of the Figures 1 and 2 each have a heating element 12 with two supply lines 14 and a plurality of conductor tracks as heating tracks 13. The heating tracks 13 are in Figure 2 not shown, but present. However, in Figure 2 the current flow S between the supply lines 14 via the heating tracks 13, which are not shown for the sake of clarity.

The supply lines 14 serve to supply power to the heating tracks 13 and are arranged outside the heating surface 11.

The heating tracks 13 cover the heating surface 11 homogeneously. In Figure 1 The heating tracks 13 run in a meandering manner between the supply lines 14.

Since only the heating tracks 13 and not the sensors 21 or the supply lines 14 are arranged in the area of the heating surface 11, neither the heating by means of the heating tracks 13 nor the transparency or translucency of the substrate is disturbed by them. The heating tracks 13 also do not have to run around or leave out the sensors 21 or the sensor supply lines 22 required for them, so that only a homogeneous, i.e. even, distribution of the heating tracks 13 over the entire heating surface 11 is possible.

However, since the functionality of the surface heating element 1 or its heating element 12 and preferably also the temperature(s) of the heating element 12 or of the entire heating surface 11 are to be monitored, at least one sensor 21 cannot be dispensed with.

In Figure 1 Therefore, a sensor carrier 20 is provided on each of two opposite sides of the substrate 10, which can also be considered as a single sensor carrier 20. Two sensors 21 are provided on each (part of the) sensor carrier(s) to determine the temperature in the area of the heating surface 11 or the heating element 12 adjacent to the respective sensor 21. For example, the functionality of the heating element 12 can be monitored by evaluating a measured actual temperature against a target temperature specified for a respective operating state.

The parts of the sensor carrier 20 or the sensor carriers 20 can be flexibly connected to the substrate 10. If a design carrier (not shown) is arranged on a rear side of the substrate 10 facing away from the front, the parts of the sensor carrier 20 or the sensor carriers 20 can be folded over the design carrier so that the temperatures can be determined by means of the sensors either through the design carrier or via a thermally conductive material which extends from the sensors to the heating element 12.

In Figure 2 the sensor carrier 20 is formed outside the heating surface 11 directly by the substrate 10 or is applied to it. For example, three sensors 21 are provided which have a common evaluation unit 23.

The invention is not limited in its implementation to the preferred embodiments given above. Rather, a number of variants are conceivable which make use of the solution presented even in fundamentally different embodiments.

Claims (10)

Surface heating element (1) with a transparent or translucent substrate (10) which forms a front side of the surface heating element (1) and which defines a flat, curved or multi-dimensionally shaped heating surface (11), and at least one sensor (21), wherein in or on the substrate (10) at least one heating element (12) is arranged, which has at least one conductor track as a heating track (13) for electrically heating the substrate (10), wherein the at least one sensor (21) is arranged outside the heating surface (11) and is designed to determine the temperature and/or the functionality of the at least one heating element (12) and/or the heating surface (11). Surface heating element according to claim 1,
wherein the at least one sensor (21) is arranged adjacent to the heating surface (11) and/or the substrate (10) as seen from the front. Surface heating element according to claim 1 or 2,
wherein the at least one heating element (12) and the at least one heating track (13) formed thereby cover the substrate (10) and/or the heating surface (11) determined by the substrate (10) by 1% to 30%. Surface heating element according to one of the preceding claims,
wherein the at least one heating track (13) is 0.1 to 0.4 mm wide. Surface heating element according to one of the preceding claims,
wherein the at least one heating track (13) the heating surface (11) covers homogeneously. Surface heating element according to one of the preceding claims,
wherein the at least one heating track (13) is formed from a transparent and/or translucent or non-transparent, electrically conductive material. Surface heating element according to one of the preceding claims, wherein the heating element (12) further comprises two supply lines (14) for power supply, which are spaced apart from one another and, as seen from the front side, are arranged on or in an edge region surrounding the substrate (10) and/or the heating surface (11) in a frame-like manner, wherein the at least one heating track (13) connects the two supply lines (14) in an electrically conductive manner. Surface heating element according to one of the preceding claims,
wherein the at least one sensor (21) is thermally contacted with the at least one heating element (12) and is designed to determine the functionality and/or the temperature via the thermal contact. Surface heating element according to one of the preceding claims, further comprising a sensor carrier (20) on, at, or in which the at least one sensor (21) is arranged, wherein the sensor carrier (20) surrounds the substrate (10) in a frame-like manner at least in sections. Surface heating element according to the preceding claim,
wherein the sensor carrier (20) and the substrate (10) are integrally formed with one another or are integrally connected to one another.

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