EP2856842B1 - Thin film heater with pyramid-shaped laser cutting pattern - Google Patents

Description

The present invention relates to a laser cut pattern for thin film heaters.

Transparent thin-film heaters are already being used in a wide variety of applications, for example as a windshield in motor vehicles, as heatable mirrors or as radiators in living spaces. In motor vehicles thin-film heaters in the form of heated windscreens or rear windows can be used to keep the vehicle windows ice-free and fogging-free. As energy costs increase, homes are getting better and better insulated. Especially low-energy and passive houses need only low heat outputs due to their good insulation, but they should always be available flexibly. Radiators with low heat dissipation, such as glass thin-film radiators, are also well suited in this area of responsibility. Such electrically operated thin-film heaters have only a short heating phase and are able to deliver their radiant heat quickly, which makes them particularly interesting for use in passive houses. Thin-film heaters can be installed without much effort and require only one power supply, which eliminates the costly installation of a complete heating system and associated piping systems. Furthermore, thin-film heaters are not only suitable for wall mounting, but can also be installed freely in the room. Transparent thin-film heaters can also be used as decorative elements by their visually appealing shape. In this case, a diverse design of the glass surface is possible, for example by screen printing. However, the design freedom of the design of thin-film heaters is limited since the required power is not high enough for all radiator formats. The previously known thin-film heaters are available only in standard formats, long narrow radiators are not yet feasible.

DE 10 2008 029 986 A1 discloses a windshield with electrically heatable transparent coating. On the two vertically opposite sides of the disc, two electrodes of the same polarity are mounted. In the middle of the disc is parallel attached to these two electrodes another electrode which has the opposite polarity. The heating current flows in each case between an outer electrode and the inner electrode, so that the disk is divided into two heating fields. Viewed individually, these two heating fields have a lower electrical resistance than a large heating field that occupies the entire width of the pane.

DE 36 44 297 A1 discloses a windshield having a conductive transparent coating having a plurality of slots in this coating. In the area of the slots, the coating is removed, whereby no current flows in these areas. This structuring results in current paths in the coating. Upon application of a voltage, the coating heats up, wherein the current density in the individual regions can be controlled in a controlled manner by the choice of the slot pattern. Thus, certain areas of the disc can be primarily freed from ice.

EP 0 250 386 discloses a transparent glass radiation heating, which is preferably used as a heated window glazing. The radiator consists of several parallel mounted glass plates of which at least one glass plate contains a metal coating on its surface. The metal coating is extremely thin and thus has no undesirable effects on the transparency of the glass heater. Due to its small thickness, this metal coating acts as a resistor when it is connected to a circuit and heats up due to the so-called Joule effect. Between the heated metal coating and the adjacent arrangement, a further metal layer is introduced, which reflects the radiant heat. Thus, the entire generated radiant heat is emitted in one direction. The two metal layers are separated by an electrically insulating air chamber.

DE 102 59 110 B3 discloses a plate element with a layer heater. The plate member includes a glass sheet provided with an electrically conductive coating. This coating is divided into rungs via dividing lines. On the coating two closely adjacent electrodes are applied. By applying a voltage, the current flows through the current paths from one electrode to the other. The coating acts as a resistor and is thereby heated. The current paths are arranged parallel to each other and interlaced, whereby the Electricity should be distributed as evenly as possible over the entire surface of the coating. Between these active regions of the coating connected to the electrodes there are passive regions in which no current flows. These passive areas are located between the active areas of the coating and serve for homogeneous temperature distribution. By delivering heat to the unheated passive areas of the coating, the heated active areas can intercept and smooth peak temperature distribution. The passive areas act as heat sinks.

Thin-film radiators generally comprise two glass plates laminated together, between which an electrically conductive layer is applied to one of the two glass surfaces. The electrically conductive layer is patterned by means of a laser, so that in the electrically conductive layer, a cutting pattern of a plurality of Heizstrompfaden is formed along which the current flows. The resulting heating field should allow the most homogeneous possible heating of the electrically conductive coating. For this purpose, all Heizstrompfade have a similar resistance and thus have a similar length. Especially with large narrow radiators, the outside heating path is too long according to the previously known patterns. As a result, the resistance of this heating path is too high compared to the heating paths located further inside, and the outer heating path is hardly traversed by current. As a result, the heater does not radiate its heat homogeneously. Thus radiators are limited with the previously known patterns in their geometry, since such patterns are not suitable for large narrow radiator. Furthermore, only radiators with comparatively low power can be produced with the previously known patterns. The previously known radiators are expensive to manufacture because the patterns used extend over the entire surface of the conductive coating. For this reason, the time required and thus the costs for the laser process are enormously high.

The object of the invention is to provide a thin-film heater which is inexpensive to produce and delivers high and homogeneous heating even with long narrow heater geometries.

The object of the present invention is achieved by a thin-film heater with pyramidal laser pattern and its use according to the independent claims 1, 15 and 16 solved. Preferred embodiments of the invention will become apparent from the dependent claims.

The thin-film heating element according to the invention comprises at least one pane composite consisting of two panes and a laminating film, wherein at least one of the panes on the inside has an electrically conductive coating and at least two connection electrodes for contacting the conductive coating. The thin-film heater has two long sides and two short sides, and preferably has a narrow, tall shape where the long side is at least twice as long as the short side. On the short side of the thin-film heater are at least two terminal electrodes that contact the conductive coating. At least one cutting pattern is introduced into the conductive coating, the conductive coating being removed in the region of the cutting pattern. As a result, in the conductive coating, heating current paths which connect the connection electrodes and through which current flows when a voltage is applied to the connection electrodes are formed. The conductive coating has an exceptional pyramidal pattern, in which large parts of the coating need not be patterned.

The pattern is composed of long cut lines that run parallel to the long side of the thin-film heater, and short cut lines that are parallel to the short side of the thin-film heater together. The long cut lines are not necessarily longer than the short cut lines, but only defined as such due to their parallelism to the long side edge. The same applies to the short cutting lines.

On the conductive coating is a heating field, which is divided by the short cutting lines into several sections n, where n is an integer> 1. The number of sections is not fixed and can be variably adjusted to the desired radiator geometry. Preferably, patterns with five to six sections are used. A section n comprises a short cutting line and the long cutting lines between this and the subsequent vertical cutting line and ends before the subsequent perpendicular cutting line. The following vertical section line is generally the short section line of the following section n + 1. In the last section, the following vertical cut line corresponds however, the final cut line. The number of long cut lines per section n + 1 increases as compared to the previous section n, while its length decreases. A heater panel contains at least two sections, a first section and a last section. Between these two sections are optionally further sections, which are referred to as the middle sections. The first and the last section of the heating field, in contrast to the middle sections a slightly modified structure. The middle sections are the same in their general construction.

In all sections n, from each short cut line, there are several outer long cut lines that terminate before the short cut line of the subsequent section n + 1 or the final cut line. In each of the spaces between these outer long cut lines in the section n, at least one further inner long cut line runs, which meets the short cut line of the subsequent section n + 1 or the final cut line of the last section.

The first section differs from the subsequent sections in that it does not begin with a short cut line. In the first section, a first outer long cutting line and a second outer long cutting line each begin at the inner edges of the terminal electrodes and terminate before the first short cutting line of the subsequent section. Between the two outer long cut lines originate one or more inner long cut lines. These inner long cutting lines meet the first short cutting line of the following section.

In the last section, the pattern ends with a short cut line, on which the inner long cut lines of this section hit. However, no further long cut lines go beyond the final cut line.

As a result of this structuring of the conductive coating, from the terminal electrodes to the final cutting line, a pattern of patterns having a pyramidal structure is obtained, the long cutting lines of which are toothed in a comb-like manner. The current must thus pass through several turns of the heating current paths on the way from one connection electrode to the other. The comb-like pattern is constructed so that the path lengths and thus the resistances of the individual Heating current paths are identical. In this way, a very homogeneous heating of the heating field is possible, whereby the performance of the thin-film heater is improved. Surprisingly, the areas of the conductive coating adjacent to the outer long cutting lines need not be patterned. In the other sections of the heating field also remain the surface areas away from the pyramidal basic shape unprocessed. In comparison with the labyrinthine patterns known from the prior art, substantially fewer laser cuts are required for structuring the conductive coating in the case of the thin-film heater according to the invention. Thus, the thin-film heater according to the invention in the production is much cheaper than the known in the prior art radiators, since the laser time can be significantly reduced. Furthermore, the thin-film heater according to the invention enables higher heat outputs and new radiator geometries.

The number of long cut lines per section n in section n + 1 increases in comparison to the previous section n and the length of the long cut lines decreases in section n + 1. In a preferred embodiment, the number of long cut lines per section n in the section n + 1 increases by two long cut lines compared to the previous section n, and the length of the long cut lines is halved in the section n + 1.

The conductive coating is preferably mounted on the inside of one of the two panes, but may also be applied to the insides of both panes, resulting in two opposing heating fields.

An edge region of the conductive coating is separated from the heating field by a peripheral parting line. The circumferential parting line is located at a small distance from the edge of the pane, so that a narrow edge area results, which preferably has a width of 0.5 cm to 2 cm. As a result, this edge region is electrically insulated. In this way, corrosion of the conductive coating is prevented in the heating field, as a beginning of the outer edge corrosion can not continue beyond the circumferential parting line.

Since the number of long cut lines per section n in each section n + 1 increases, while the distance between adjacent long section lines remains the same, the length of the short cut lines with increasing distance from the terminal electrodes also increase.

The pattern of the thin-film heater is preferably mirror-symmetrical over its longer centerline. As a longer center line while the center line is referred to, which is parallel to the long side of the thin-film heater. This symmetry ensures that the heating current paths have a constant area. This achieves a constant current density along the entire coating. At the same time, the number of laser cuts needed to create the pattern is minimized. However, pyramidal patterns are also conceivable which have no mirror symmetry along the center line.

In the case of very large thin-film heaters with a single cutting pattern, the heating current path running on the outside becomes too long, as a result of which the heating power in this area drops sharply. This is the case especially with wide and high radiators. In order to avoid such a loss of heating power, a plurality of cutting patterns can be introduced in the conductive coating. Preferably, two patterns are used whose long cutting lines are parallel to each other and to the long side of the thin-film heater. This results in two mirror-symmetric small heating fields on the thin-film heater whose outer Heizstrompfade each have an adequate length, so that a good heating performance is guaranteed. However, it is also conceivable a mirror-symmetrical arrangement of three or more patterns.

For thin-layer radiators with multiple patterns, adjacent patterns have a common terminal electrode of the same polarity located between the patterns on the short side of the thin-film heater. The terminal electrodes of the opposite polarity are also located above and below the cutting pattern also on the short side of the thin-film heating element.

The final cutting line in the last section of the heating field can also optionally coincide with the circulating dividing line. Such a pattern is chosen especially for large heaters with multiple patterns. This is how the outside is going Heating path lengthened, whereby a uniform heating is possible even with multiple patterns per thin-film heater.

The Heizstrompfade between the terminal electrodes with opposite polarity have the same path length and thus also the same resistance in all sections of the thin-film heater according to the invention. As a result, current flows through the outside of the heating current paths to the same extent as the internal heating current paths. In this way, a uniform heating of all coating areas and thus a higher performance of the thin-film heater can be ensured.

The first and the second pane of the thin-film heating element contain soda-lime glass, quartz glass and / or borosilicate glass. Float glass is preferably used. The glass sheets are preferably thermally biased.

The first and the second disc of the thin-film heater have a thickness of from 1 mm to 20 mm. Preferably, slices of thickness 2 mm to 8 mm are used.

The laminating film comprises polyvinyl butyral, ethylene vinyl acetate, polyurethane and / or mixtures and / or copolymers thereof. Preferably, polyvinyl butyral is used.

The laminating film has a thickness of from 0.1 mm to 0.8 mm, preferably from 0.3 mm to 0.5 mm.

The conductive coating of the thin-film heating element can be both silver, gold, copper, indium, tin, zinc and / or mixtures and / or oxides and / or alloys thereof, as well as TCO ( transparent conductive oxide ) layers such as indium tin oxide ( ITO). Silver coatings of several individual layers of silver are preferably used. In order to ensure a high transparency of the thin-film heating element, an antireflection coating of the silver layer can be effected by means of silicon nitride. The conductive coating is thermally highly resilient and can thus be applied to the surface before tempering the glass sheets. The conductive coating is preferably applied by vapor deposition techniques, for example chemical vapor deposition (CVD) or physical vapor deposition (PVD). Particular preference is given to using sputtering processes, for example magnetron sputtering. By means of these methods, the metal layer can be applied very evenly to the surface of the glass sheet.

The conductive coating has a thickness of from 1 nm to 500 nm, preferably from 50 nm to 250 nm.

The conductive coating has a sheet resistance of 0.5 Ω to 15 Ω per square, preferably 1 Ω to 10 Ω per square, more preferably 2 Ω to 7 Ω per square. The surface resistance of the coating must be adjusted so that the thin-film heater reaches a maximum temperature of 80 ° C to 90 ° C during operation, as required by DIN EN 60335. This temperature limitation prevents persons from getting burned when they touch the thin-film radiator. The greater the thickness or the conductor cross-section of the conductive coating, the lower the sheet resistance. With low surface resistances higher current intensities occur at the same voltage, whereby larger powers are achieved. Higher currents, however, also cause a higher temperature of the thin-film heater. The maximum possible outputs are therefore limited by the temperature limitation of 80 ° C to 90 ° C. Since the current levels depend on both the resistance and the applied voltage, thin-film heaters with different surface resistances, which are adapted to the local grid voltages, are provided worldwide. For the American market with mains voltages of 110 V, thin-film heaters with lower surface resistances are therefore produced than for the European market with mains voltages of usually 230 V.

The pattern in the conductive coating is produced by means of lasers, etching and / or ablation. Preference is given to using laser processes for removing the coating. The lasing takes place with a wavelength of 300 nm to 1300 nm. The wavelength used depends on the type of coating. Pulsed solid-state lasers are preferably used as the laser source.

In the area of the cut lines, at least 80 percent by weight, preferably at least 90 percent by weight of the metal coating is removed from the glass surface.

In contrast to the point or circular connection electrodes known from the prior art, the thin-layer heating element according to the invention has two or more connection electrodes with an elongate shape. These are located on the short side of the thin-film heater and are aligned parallel to this short side.

The connection electrodes can be applied to the pane either before or after the deposition of the conductive coating. The connection electrodes are preferably applied after deposition of the conductive coating. For this purpose, an electrically conductive metal paste is applied to the inner side of the disk and then baked. The terminal electrodes are located on the same side of the disc as the electrically conductive coating, whereby a permanent electrical contact between terminal electrode and conductive coating is ensured by burning the metal paste. The metal paste preferably contains silver, gold, platinum, palladium, copper, nickel, manganese, iron and / or mixtures or alloys thereof, particularly preferably silver. The connection electrodes are connected to the power source via an electrical conductor.

Furthermore, the invention comprises a method for producing a thin-film heating element with a pyramidal laser pattern. In a first step, a conductive coating is applied to a first pane. The conductive coating is preferably applied to the pane by means of a PVD process. In the conductive coating, a pyramidal pattern is then introduced by means of lasers, the long cutting lines are meshed with each other like a comb. On the short side of the first disc, two or more terminal electrodes are applied by baking an electrically conductive metal paste. The terminal electrodes are applied as elongated strips parallel to the short side of the first disc and contact the conductive coating. On the inside of the first pane, which carries the conductive coating and the connection electrodes, a laminating film is placed in the next step and a second pane is placed on the laminating film. This arrangement of first disc with conductive coating and terminal electrodes, laminating film and second disc is first pre-evacuated and finally in the autoclave for 2.5 hours at 80 ° C to 135 ° C and 7 bar to 13 bar laminated.

Furthermore, the invention comprises the use of a thin-film heating element as a functional and / or decorative single piece and / or as a built-in part in furniture, appliances, buildings and vehicles. The thin-film radiator according to the invention is preferably used as a freestanding or wall-mounted radiator in living spaces, as heatable facade glazing or as a heatable vehicle window, ship window or aircraft windscreen.

Special embodiments of the thin-film heater according to the invention with a pyramidal laser pattern include thin-film heaters with rounded corners up to ellipsoidal thin-film heaters. As a long side of the thin-film heater, to which the long cutting lines are parallel, thereby defining the voltage applied to the long side radiator tangent is defined. Other embodiments of the thin film heater according to the invention with a pyramidal laser pattern include a breakage sensor in the edge strip of the thin film heater. The edge strip is divided into different areas. In one of these areas a weak voltage is applied. Damage to the radiator can thus be detected by a drop in the voltage in this area. Other embodiments of the thin film heater with pyramidal laser pattern include thin film heater with Messstrompfaden for temperature measurement at different points of the radiator. In a further embodiment of the thin-film heating element according to the invention, the connection electrodes are combined to form a busbar. This design is particularly advantageous for very wide thin-film radiators with more than 3 terminal electrodes.

In the following the invention will be explained in more detail with reference to a drawing. The drawing does not limit the invention in any way.

• Figur 1a eine schematische Ansicht des erfindungsgemäßen Dünnschichtheizkörpers mit pyramidenförmigem Laserschnittmuster.
• Figur 1b einen vergrößerten Ausschnitt des pyramidenförmigen Laserschnittmusters des erfindungsgemäßen Dünnschichtheizkörpers.
• Figur 2 eine schematische Ansicht des erfindungsgemäßen Dünnschichtheizkörpers mit beispielhaft dargestellten Heizstrompfaden.
• Figur 3 eine schematische Ansicht des erfindungsgemäßen Dünnschichtheizkörpers mit zwei pyramidenförmigen Laserschnittmustern.
• Figur 4 einen schematischen Querschnitt des erfindungsgemäßen Dünnschichtheizkörpers.
• Figur 5 ein Fließschema des Verfahrens zur Herstellung des erfindungsgemäßen Dünnschichtheizkörpers.
• Figur 6 zwei schematische Darstellungen der Thermographien eines Dünnschichtheizkörpers nach dem Stand der Technik.
• Figur 7 eine schematische Darstellung einer Thermographie des erfindungsgemäßen Dünnschichtheizkörpers.

Show it:

• FIG. 1a a schematic view of the thin film heater according to the invention with pyramidal laser pattern.
• FIG. 1b an enlarged section of the pyramidal laser cut pattern of the thin-film heater according to the invention.
• FIG. 2 a schematic view of the thin-film heater according to the invention with Heizstrompfaden shown by way of example.
• FIG. 3 a schematic view of the thin film heater according to the invention with two pyramidal laser cut patterns.
• FIG. 4 a schematic cross section of the thin-film heater according to the invention.
• FIG. 5 a flow diagram of the method for producing the thin-film heater according to the invention.
• FIG. 6 two schematic representations of the thermographies of a thin film heater according to the prior art.
• FIG. 7 a schematic representation of a thermography of the thin film heater according to the invention.

FIG. 1a shows a schematic view of the thin-film heater (1) according to the invention with a pyramidal laser pattern. The thin-film heating element (1) comprises a first pane (2.1) on which a conductive coating (3) and two connection electrodes (4.1, 4.2) are applied, a laminating film (17) and a second pane (2.2). The thin-film heater (1) has two long sides (8) and two short sides (7), which are perpendicular to each other. The two terminal electrodes (4.1, 4.2) have an elongated shape and are arranged on a short side (7) of the thin-film heating element (1). The terminal electrodes contact the conductive coating (3) so that a voltage applied to the terminal electrodes (4.1, 4.2) is also applied to the coating. In the conductive coating (3) has a cutting pattern (13) is introduced. In these areas is the conductive coating (3) from the surface of the first disc (2.2) removed, whereby these areas are electrically isolated. This structuring produces heating current paths (12.n) in the conductive coating (3). These heating current paths (12.n) are supplied with current when a voltage is applied to the connection electrodes (4.1, 4.2). The cutting pattern (13) of the conductive coating (3) is divided into long cutting lines (5) and short cutting lines (6), wherein the long cutting lines (5) differentiate between outer long cutting lines (5.1) and inner long cutting lines (5.2) , All long cutting lines (5) are parallel to the long side (8) of the thin-film heater (1), while the short cutting lines (6) are arranged parallel to the short side. The long cutting lines (5) and the short cutting lines are perpendicular to each other. The heating field (10) resulting from the structuring is subdivided into a plurality of sections (11.n) which are delimited by the short cutting lines (6). In this case, at least a first section (11.1) and a last section (19) are necessary, between which optionally a plurality of middle sections (11.2) are located. In the present embodiment, three middle sections (11.2a, 11.2b, 11.2c) are present. In the first section (11.1), a first outer long cutting line (5.1a) and a second outer long cutting line (5.1b) bear against the inner edges of the connecting electrodes (4.1, 4.2). Between these two outer long cutting lines (5.1a, 5.2b) runs a first inner long cutting line (5.2a). The total number of long cutting lines (5) of the first section (11.1) thus amounts to three. In each subsequent section (11.n), the number of long cut lines (5) per section (11.n) is increased by two while the length of the long cut lines (5) is halved. The length of the short cutting lines (6) increases from the first section (11.1) to the last section (19). The first outer long section line (5.1a) and the second outer long section line (5.1b) terminate before the first short section line (6.1) of the second section (11.2a), while the first inner long section line (5.2a) terminates at the first short section Cutting line (6.1) hits. In the second section (11.2a) arise on the first short cutting line (6.1) three outer long cutting lines (5), which ends before the short cutting line (6) of the subsequent section. In the interstices of these outer long cutting lines (5) in each case an inner long cutting line (5), which meets the short cutting line (6) of the subsequent section. The two subsequent middle sections (11.2b, 11.2c) are constructed analogously to the first middle section (11.2a). The last section (19) is delimited by a final cutting line (9) on which the long cutting lines (5) running in this section meet. By such an arrangement of the individual cutting lines (5, 6) the long cut lines (5) of the pyramidal pattern (13) are meshed with each other like a comb. Surprisingly, this unusual pattern (13) results in very homogeneous heating powers while at the same time reducing the number of laser cuts. The pattern (13) preferably has a mirror symmetry over the longer centerline (16). At the edge of the thin-film heating element (1), a narrow edge region (14) is separated from the heating field (10) by a peripheral parting line (15). This edge region (14) is thereby electrically insulated.

FIG. 1b shows an enlarged section of the pyramidal laser cut pattern of the thin-film heater according to the invention. This in FIG. 1a described cutting pattern comprises a plurality of cutting lines, which can be largely assigned to the two groups of the short cutting lines (6) and the long cutting lines (5). The long cutting lines (5) are in turn divided into outer long cutting lines (5.1) and inner long cutting lines (5.2). The short cutting lines (6) run parallel to the short side (7) of the thin-film heating element (1), while the long cutting lines are arranged parallel to the long side (8). From each short cutting line (6) go out several outer long cutting lines (5.1), wherein in the spaces between two outer long cutting lines (5.1) each have an inner long cutting line (5.2).

FIG. 2 shows a schematic view of the thin-film heater (1) according to the invention with Heizstrompfaden shown by way of example. The thin-film heating element (1) comprising a first pane (2.1), laminating film (17), second pane (2.2), long sides (8) and short sides (7) has a surface-applied conductive coating (3) and two connection electrodes (4.1, 4.2) on the short side (7). On the conductive coating (3) is a pattern (13) analogous to that in FIG. 1 applied, wherein the long cutting lines (5) parallel to the long side (8) of the thin-film heater (1) and the short cutting lines (6) and the final cutting line (9) perpendicular thereto. As a result, a heating field (10) is formed on the conductive coating (3). A narrow edge region (14) is separated from the heating field (10) by a circumferential dividing line (15) and is electrically insulated. In the heating field (10), different heating current paths (12.n) are formed by the structuring of the conductive coating (3), of which a first heating current path (12.1), one of the middle heating current paths (12.2) and one last heating current path (12.3) are shown by way of example. The other heating current paths (12.n) are for the sake of clarity not shown. The current always flows through the heating current paths (12.n) from one of the negative connection electrodes (4.2) to the positive connection electrodes (4.1). The heating current paths (12.n) all have the same length and thus also the same resistance, so that all the heating current paths (12.n) are equally heated and the thin-layer heating element (1) has a very homogeneous heating power.

FIG. 3 shows a schematic view of the thin-film heater (1) according to the invention with two pyramidal laser cut patterns. The thin-film heating element (1) comprises a first pane (2.1), a laminating film (17) and a second pane (2.2) and a long side (8) and a short side (7). The electrically conductive coating (3) applied to the first pane (2.1) is subdivided by a first pattern (13.1) and a second pattern (13.2) into heating current paths (12.n). The first pattern (13.1) and the second pattern (13.2) are mirror-symmetrical to each other over the longer center line (16). On a short side (7) of the thin-film electrodes (1) is located between the two patterns (13.1, 13.2), a common negative terminal electrode (4.2). Above and below the cutting patterns (13.1, 13.2), a first positive connection electrode (4.1) and a second positive connection electrode (4.3) are likewise arranged on the short side (7) of the thin-layer heating element (1). The two cutting patterns (13.1, 13.2) comprise long cutting lines (5) and short cutting lines (6), which are analogous to those in FIG FIG. 1 placed patterns are placed. All long cut lines (5) are parallel to the long side (8), while the short cut lines (6) perpendicular to this. An edge region (14) of the thin-film heating element (1) is separated from the heating field (10) by a peripheral parting line (15), the peripheral parting line (15) simultaneously functioning as the final parting line of the two cutting patterns (13.1, 13.2).

FIG. 4 shows a schematic cross section of the thin-film heater (1) according to the invention. On a first disc (2.1), a conductive coating (3) is applied flat. In direct contact with the conductive coating (3) at least two connection electrodes (4.1, 4.2) are mounted. The connection electrodes (4.1, 4.2) are connected to the power source via electrical connections (18). On the conductive coating (3) a laminating film (17) is placed. The arrangement is covered by a second disc (2.2).

FIG. 5 shows a flow chart of the method for producing the thin-film heater (1) according to the invention. In a first step, a conductive coating (3) is applied to a first pane (2.1). Then, by means of lasers, a pyramid-shaped cutting pattern (13) is introduced into the conductive coating (3), wherein the long cutting lines (5) are meshed with one another like a comb. On the short side (7) of the first pane (2.1), two or more connection electrodes (4.1, 4.2, 4.3) are applied by burning in an electrically conductive metal paste such that the connection electrodes (4.1, 4.2, 4.3) cover the conductive coating (3). to contact. On the first disc (2.1) a laminating film (17) and on the laminating film (17) a second disc (2.2) is placed. The laminating film (17) is placed on the side of the first disk (2.1) which carries the conductive coating (3) and the connection electrodes (4.1, 4.2, 4.3). The arrangement of first pane (2.1) with conductive coating (3) and connection electrodes (4.1, 4.2, 4.3), laminating film (17) and second pane (2.2) is laminated in an autoclave.

FIG. 6 shows the schematic representation of two thermographies of a known in the prior art thin-film heater. The thermographs show a temperature drop from the inner area of the thin-film heater to the outer edge. In the inner area several partly extended Hot Spots (I) are recognizable. These so-called hot spots (I) are areas with a significantly higher temperature compared to the average temperature. Adjacent to the hot spots is a medium temperature zone (II) with a relatively homogeneous temperature distribution. The edge of the radiator is also visible as a colder area (III), in which the temperature is below the average temperature. Some of these colder areas (III) are also visible inside the radiator. The lack of homogeneity of the known in the art thin film heater is clearly visible.

FIG. 7 shows the schematic representation of a thermography of the thin-film heater according to the invention. Inside the thin-film radiator are some spatially very limited hot spots (I), in which the temperature is above the average temperature. Inside the thin-film radiator also some colder areas (III) are recognizable. To the edge of the radiator down the temperature drops, the Surprisingly, thin film heater according to the invention has only a very narrow colder region (III) in the edge region.

The thin-film heater according to the invention has, as a comparison of the thermographies in FIG. 6 and FIG. 7 shows a much higher homogeneity than the known prior art models.

The invention will be explained in more detail below with reference to the thermographs of the thin-film heating element according to the invention and of a thin-layer heating element according to the prior art, the maximum powers and the production times of both thin-layer heating elements.

In two test series, the maximum power, the production time and the homogeneity of the thin-film heater according to the invention were compared with a thin-film heater according to the prior art. In both test series, a thin-film heating element comprising a first pane (2.1) with a conductive coating (3), a laminating film (17) and a second pane (2.2) was used. The two longer side edges of the thin-film heating element (1) were defined as long sides (8) and the two short side edges as short sides (7). Float glass with a thickness of 6 mm was used as the first pane (2.1) and the second pane (2.2). The laminating film used was a PVB film having a thickness of 0.38 mm. The conductive coating (3) was applied by means of magnetron sputtering on the first disc (2.1). The connection electrodes (4.1, 4.2) were produced by applying and burning in a silver paste. The structuring of the conductive coating (3) took place by means of laser treatment. On the first disc (2.1) with processed conductive coating (3) and terminal electrodes (4.1, 4.2), a laminating film (17) was placed and the laminating film (17) covered with a second disc (2.2). This arrangement was laminated for 2.5 hours at 80 ° C to 135 ° C and 7 bar to 13 bar. The homogeneity of the thin-film radiators was investigated by measuring the colder edge areas visible in the thermographs in different radiator sections and placing them in relation to the total width of the radiator. The corresponding measurements were carried out in the lengths ⅛, ¼, ½, and ¾ based on the total length of the long side (8) and starting at the lower short side (7) of the thin-film heater. The values given for the thin-film radiator according to the prior art correspond to the average values of the two in FIG. 6 schematically illustrated thermographies.

The thin film heaters were connected to a power supply and after reaching a constant temperature (about 20 minutes) at maximum power was using an infrared camera a thermography (schematic representations in FIG. 6 and 7 ) of the thin-film heaters. To ensure a sufficient detail of the infrared images, the images were taken in several sections. The individual pictures were then combined to form a complete picture.

a) Example 1: Maximum power, production time and homogeneity of the thin-film heater according to the invention

The thin-film heating element (1) according to the invention with a size of 400 mm × 1800 mm has two elongate connection electrodes (4.1, 4.2) on the short side (7) of the thin-layer heating element (1). In the conductive coating (3) of the thin-film heating element (1), a pyramid-shaped cutting pattern (13) is introduced whose long cutting lines (5) are meshed with each other like a comb. For recording the thermography ( FIG. 6 ), the electrical connections (18) located at the connection electrodes (4.1, 4.2) were connected to a power supply. A voltage of 230 V was applied to the heating field (10).

b) Comparative Example 2: Maximum performance, production time and homogeneity of a thin film heater according to the prior art

The Thermovit Elegance (Saint-Gobain Glass Solutions) thin-film heater, which is known in the art, has a size of 400mm x 1800mm and has two small round terminal electrodes. The cut lines extending from one connection electrode to the other extend in a labyrinth-like manner over the entire conductive coating analogously to the sectional patterns described in the prior art (for example DE 102 59 110 B3 and WO 2012/066112 ). To record the thermography, the electrical connections were connected to a power source and a voltage of 230 V applied.

Table 1 shows the maximum performance of the thin-film heater according to the invention and of a thin-film heater known from the prior art and the savings in production time achieved in the laser process in comparison. <b> Table 1 </ b> Max. power Time saving laser process example 1 720W 50% Comparative Example 2 540 W = 0%

Table 2 shows the percentages of cold edge areas on the total cross-section in different lengths of the thin-film heaters. <b> Table 2 </ b> Percentage of cold edge areas longitudinal section example 1 Comparative Example 2 ⅛ 9.6% 34.3% ¼ 9.6% 24.8% ½ 9.3% 24.4% ¾ 9.6% 22.6%

In the production of the thin-film heating element according to the invention, the time required for the laser process can be halved in comparison with a thin-film heating element according to the prior art (see Table 1). The total length of all laser cuts in the thin-film heater according to the invention by about 50% less than usual in the prior art. The reduction of the laser cuts thus also leads to a corresponding time savings. As the laser process is the slowest step in a series of production steps, the entire manufacturing process is enormously accelerated. The time required for this step is also crucial for the cost of the production process, since the laser machining is lengthy and therefore expensive. An acceleration of this step thus allows a significant cost savings. In addition to these economic advantages, the thin-film heater according to the invention also offers a significantly higher heating power (see Table 1). The pyramid-shaped pattern with comb-toothed long cut lines is particularly suitable for narrow high radiators. In such forms, the thin-film heaters known from the prior art only provide insufficient heating power, since the heating current path running on the outside has too high a resistance. Thus, not all heating current paths are equally flowed through by electricity and the maximum power is reduced. For this reason, inhomogeneities occur in the heating power, as in the thermographs (see schematic diagrams FIG. 6 and FIG. 7 ) clearly recognizable. The thermographs show a temperature drop from the inner area to the outer edge of the thin-film heater. In the inner region of the radiator, so-called hot spots (I) appear in both thin-layer radiators, which, however, have a greater extent in the thin-layer radiator known from the prior art. The hot spots (I) inside the radiator are followed by an area of medium temperature (II) with a relatively homogeneous temperature distribution. In the edge area of the radiator a colder area (III) can be seen in all thermographies. A comparison of the thermographs of the thin-film heater according to the invention and the thin-film heater according to the prior art reveals the substantially higher homogeneity of the thin-film heater according to the invention even at first glance. A more precise evaluation of the proportion of cold edge areas on the total cross-section clearly confirms this (Table 2). The thin-film radiator according to the invention has over the entire length of the radiator a very small constant edge portion of less than 10%. The thin-film heater according to the prior art has especially in the lower area (Length ⅛, Table 2) over a very high margin of about 34% which decreases towards the top, but does not fall below 20%. The problem of lack of homogeneity occurs especially in long narrow radiators, since the outboard Heizstrompfad has thin film heaters according to the prior art, too high a resistance. Despite this particularly narrow high shape of the thin-film heater according to the invention, surprisingly, an exceptionally high homogeneity can be achieved.

The fact that a novel cutting pattern, despite a reduction of the laser cuts, provides a more homogeneous heat output and a higher maximum output was surprising and unexpected to the person skilled in the art. The enormous reduction of the laser cuts of the thin-film heater according to the invention is of decisive advantage with regard to a cost reduction of the production process.

LIST OF REFERENCE NUMBERS

1

thin film heater

2

slices

2.1

first disc

2.2

second disc

3

conductive coating

4

terminal electrodes

4.1

first positive connection electrode

4.2

negative connection electrode

4.3

second positive connection electrode

5

long cutting lines

5.1

outer long cut lines

5.1a

first outer long cut line

5.1b

second outer long cutting line

5.2

inner long cut lines

5.2a

first inner long cut line

6

short cutting lines

6.1

first short cutting line

7

short page

8th

long page

9

final cut line

10

heating field

11

sections

11.1

first section

11.2

middle sections

11.2a

second part

11.2b

third section

11.2c

fourth section

12.n

Heizstrompfade

12.1

first heating current path

12.2

medium heating current paths

12.3

last heating current path

13

patterns

13.1

first pattern

13.2

second pattern

14

border area

15

circumferential dividing line

16

longer centerline

17

laminating

18

electrical connections

19

last section

I

hot spots

II

Areas of medium temperature

III

colder areas

Claims (16)

1. Thin layer heating element (1) comprising at least a laminated pane consisting of a first pane (2.1), a laminating film (17), a second pane (2.2), two long sides (8), two short sides (7), a laminar electrically conductive coating (3) applied at least on the inside of the first pane (2.1), at least two connection electrodes (4.1, 4.2, 4.3) on the short side (7) of the thin layer heating element (1) for contacting the conductive coating (3), at least one electrical connection (18), and at least one cut pattern (13) having heat current pathways (12. n), which connect the connection electrodes (4.1, 4.2, 4.3), wherein

   a) the cut pattern (13) has long cut lines (5.1, 5.2), including outer long cut lines (5.1) and inner long cut lines (5.2), which run parallel to the long side (8) of the thin layer heating element (1), and short cut lines (6), which run parallel to the short side (7) of the thin layer heating element (1), ,

   b) on the conductive coating (3), there is a heating field (10), which is divided by the short cut lines (6) into a plurality of sections (11.n), where n is an integer > 1,

   c) the number of long cut lines (5.1, 5.2) per section (11.n) increases in the section (11.n+1) compared to the section (11.n) and the length of the long cut lines (5.1, 5.2) decreases in the section (11.n+1),

   d) from each short cut line (6) of the section (11.n), a plurality of outer long cut lines (5.1) branch out, which end before the short cut line (6) of the section (11.n+1) or a final cut line (9),

   e) in all intermediate spaces between two outer long cut lines (5.1) in the section (11.n), in each case at least one inner long cut line (5.2) runs and strikes the cut line (6) of the section (1 I.n+1) or the final cut line (9), and

   f) in the first section (11.1), a first outer long cut line (5.1 a) and a second outer long cut line (5.1 b) begin in each case on the inner edge of the connection electrodes (4.1, 4.2) and end before a first short cut line (6.1)

   such that the conductive coating (3) has a pyramid-shaped cut pattern (13) from the connection electrodes (4.1, 4.2) all the way to the final cut line (9), whose long cut lines (5) are meshed with each other in a comb-like manner.
2. Thin layer heating element according to claim 1, wherein the number of the long cut lines (5.1, 5.2) per section (II.n) increases in the section (11.n+1) compared to the section (11.n) by two long cut lines (II.n) and the length of the long cut lines (5.1, 5.2) is halved in the section (11.n+1).
3. Thin layer heating element according to claim 1 or 2, wherein the conductive coating (3) is applied on the first pane (2.1) and the second pane (2.2).
4. Thin layer heating element (1) according to one of claims 1 through 3, wherein an edge region (14) is separated from and is electrically isolated from the heating field (10) by a surrounding separation line (15).
5. Thin layer heating element (1) according to one of claims 1 through 4, wherein the length of the short cut lines (6) increases with the increasing distance of the associated section (11) from the connection electrodes (4.1, 4.2).
6. Thin layer heating element (1) according to one of claims 1 through 5, wherein the cut pattern (13) is mirror symmetrical over its longer center line (16).
7. Thin layer heating element (1) according to one of claims 1 through 6, wherein a plurality of cut patterns (13) is applied on at least one of the two panes (2) such that the long cut lines (5) of the two cut patterns (13) are parallel to each other and to the long side (8) of the thin layer heating element (1) and the arrangement is mirror symmetrical over the longer center line (16) of the thin layer heating element (1).
8. Thin layer heating element (1) according to claim 7, wherein adjacent cut patterns (13) have a common connection electrode (4.1, 4.2, 4.3) of the same polarity.
9. Thin layer heating element (1) according to one of claims 1 through 8, wherein the final cut line (9) coincides with the surrounding separation line (15).
10. Thin layer heating element (1) according to one of claims 1 through 9, wherein the resistance and the path length of the heating current paths (12.n) between connection electrodes (4.1, 4.2, 4.3) with opposite polarity are the same in all sections (11).
11. Thin layer heating element (1) according to one of claims 1 through 10, wherein the conductive coating (3) contains silver, gold, copper, indium, tin, zinc, indium tin oxide, and/or mixtures and/or oxides and/or alloys thereof, preferably silver.
12. Thin layer heating element (1) according to one of claims 1 through 11, wherein the cut pattern (13) is generated by removal of the conductive coating by means of lasering, etching, and/or ablation, preferably lasering.
13. Thin layer heating element (1) according to one of claims 1 through 12, wherein the connection electrodes (4.1, 4.2, 4.3) have an elongated shape and are arranged parallel to the short side (7) of the thin layer heating element (1).
14. Thin layer heating element (1) according to one of claims 1 through 13, wherein the connection electrodes (4.1, 4.2, 4.3) are produced before or after deposition of the conductive coating (3) by application and baking of an electrically conductive metal paste onto the same pane surface as the conductive coating (3).
15. Method for producing a thin layer heating element (1) according to claims 1 through 14, wherein

    m) a cut pattern (13) is introduced into the conductive coating (3) by lasering,

    n) two or more connection electrodes (4.1, 4.2, 4.3) are applied on one of the short sides (7) of the first pane (2.1) by baking of an electrically conductive metal paste,

    o) a laminating film (17) is placed on the surface of the first pane (2.1) which carries the conductive coating (3) and the connection electrodes (4.1, 4.2, 4.3), and at least one second pane (2.2) is placed on the laminating film (17), and

    p) the arrangement is autoclaved.
16. Use of a thin layer heating element (1) according to one of claims 1 through 15 as a functional and/or decorative individual item and/or as a built-in component in furniture, appliances, buildings, and vehicles, preferably as a freestanding or wall-mounted heater in living areas, as a heatable façade glazing or as a heatable vehicle window pane, watercraft window pane, or aircraft window pane.

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