DK2856842T3

DK2856842T3 - Thin film heater with pyramid shaped laser cut pattern

Info

Publication number: DK2856842T3
Application number: DK13700306.7T
Authority: DK
Inventors: Walter Schreiber; Sabine Velden; Dang Cuong Phan
Original assignee: Saint Gobain
Priority date: 2012-06-01
Filing date: 2013-01-16
Publication date: 2016-07-25
Also published as: WO2013178369A1; EP2856842A1; EP2856842B1

Description

THIN FILM HEATER WITH PYRAMID-SHAPED LASER CUTTING PATTERN

The present invention refers to a laser cutting pattern for a thin film heater.

Transparent thin film heaters are known per se to be used within most different fields of application, e.g. as vehicle window panes, as heated mirrors or as heating element in living areas. In vehicles thin film heater elements can be used in form of heated windshields or backlights to keep the vehicle windows ice free and misty free. During the course of rising energy costs dwelling-houses are better and better insulated. Already low energy and passive houses utilize due to their good insulation only a small heating energy, which always has to be disposed in a flexible manner. In this problem area also heaters with lower heat supply are well suited, like thin film heaters of glass. Such electrical driven thin film heaters make use of only a short heating phase and are capable to supply their radiation heat in a fast way, making them especially interesting for use in passive elements. Thin film heaters can be installed without great complication and need a power source only, thus the complicated installation of a complete heat arrangement and tube systems therefore are disposed of. Furthermore thin film heaters are suitable not only for wall applications but can be arranged as free items in the room as well. Transparent thin film heaters can also due to their optical pleasant form be used as decorative elements. Then many kinds of configuration of the glass surfaces are possible, for instance by screen-printing. The freedom of configuration with reference to the design of the thin film heaters is however restricted, since the power used is not high enough in all heater forms. Hitherto known thin film heaters are found in standard forms only, long narrow heaters are not realized up to now. DE-A1 -10 2008 029 986 describes a vehicle window pane with electrical heated transparent coating. On the two sides vertically opposite each other of the pane there are two electrodes of similar polarity. In the center of the pane in parallel with the two electrodes there is a further electrode arranged having the opposite polarity. The heat current flows between an external electrode and the inside electrode such that the pane is divided in two heating fields. These two heating fields, viewed each individually, have a smaller electrical resistance as a large heating field including the whole width of the pane. DE-A1-36 44 297 describes a vehicle window pane with a conductive transparent coating, which has several recesses in the coating. Within the area of the recesses the coating is removed, thus no current flows in these areas. By this structure current pathways are obtained in the coating. By supplying a voltage the coating is heated, whereby the current density in the separate areas can be controlled in a target orientated manner by the selection of the recess design.

Thus in first hand determined areas of the pane can be relieved from ice. EP 0 250 386 describes a transparent glass radiation heating which preferably is used as heated window pane. The heater consists of several glass panels arranged in parallel and from which at least one glass panel includes a metal coating on the top surface thereof. The metal coating is extreme thin and has no undesired influence on the transparency of the glass heater. Due to the small thickness this metal coating acts as a resistance when it is connected to a current circuit and is heated by the so called Joule effect. Between the two metal coatings and the adjacent device a further metal layer is introduced, which reflects the radiation heat. Thus all the radiation heat generated will be delivered in one direction. The two metal layers are separated from each other by an electric isolating air chamber. DE-B3-102 59 110 describes a disc element with a film heater. The disc element includes a glass pane being provided with an electric conductive coating. This coating is separated in current pathways by separation lines. Onto the coating there are two tight beside each other laying electrodes applied. By supply of a voltage the current flows through the current pathways from one electrode to the other. The coating acts as a resistance and thus it is heated. The current pathways are parallel to each other and intertwined with each other, such that the current is to be distributed as equal as possible over the whole area of the coating. Between those with the electrodes connected active areas of the coating there are passive areas where no current flows. The passive areas are to be found between the active areas of the coating and serve for the homogenous temperature distribution. In that the heated active areas deliver heat to the unheated passive areas of the coating top heat can be took care of by the temperature distribution and is smoothed. Thus the passive areas act as heat sinks.

Thin film heaters comprise in general two with each other laminated glass panes between which an electric conducting layer is applied onto one of the two glass surfaces. The electric conductive layer is structured with a laser such that in the electric conductive layer there is formed a cut pattern of several heat current pathways along which the current flows. Thereby the resulting heat field should make a heating possible being as homogenous as possible of the electric conducting layer. For that all the heat current pathways have to have a similar resistance and thus a similar length. Especially at large narrow heaters the outer existing heater pathway is too long in cut patterns known up to now. Thus the resistance of this heater pathway is too high compared with the heater pathways further inside thereof and almost no current will flow through the outer heater pathway. Accordingly the heater does not radiate its heat in a homogenous manner. Thus heaters with cut patterns of the geometry known per se are restricted as such cut patterns are not suitable for large narrow heaters. Furthermore with the cut patterns known up to now only heaters with comparatively low power can be manufactured. The heaters known have a complicated manufacturing as the cut pattern used is covering the whole area of the conductive layer. Of this reason the time used and consequently the costs for the laser process are tremendously high.

The purpose of the invention is to obtain a thin film heater which is cost effective to produce and by long narrow heater geometries also delivers high as well as homogenous heat effects.

The purpose of the present invention is solved with a thin layer heating element having a pyramid-shaped laser cut pattern and the use thereof according to the independent claims 1,15 and 16. Preferred developments of the invention are to be found in the dependent claims.

The inventive thin layer heating element comprises at least a laminated pane consisting of two panes and a laminating film, whereby at least one of the panes on its inner side has an electric conducting coating and at least two connection electrodes for contacting the conductive coating. The thin layer heating element comprises two long sides and two short sides and preferably has a narrow high form, where the long side is at least twice as long as the short side. At the short sides of the thin layer heating element there are at least two connection electrodes, which are contacting the conductive coating. In the conductive coating there is at least one cut pattern introduced, whereby the conductive coating is removed within the area of the cut pattern. Thereby heat current pathways are obtained in the conductive coating which connect the connection electrodes and by supply of a voltage to the connection electrodes current flows through them.

The conducive coating has an unusual pyramid-shaped cut pattern by which large parts of the coating do not need to be structured.

The cut pattern is formed by long cut lines being parallel to the long sides of the thin layer heating element and by short cut lines being parallel to the short sides of the thin layer heating element. The long cut lines are not necessarily longer than the short lines, but only named as such due to the fact that they are parallel to the long side edges. Corresponding apply to the short cut lines.

On the conductive coating there is a heating field which by the short cut lines is separated into several sections n, where n is an integer > 1. The number of sections is not determined and can be variably adapted to the heating element geometry wanted. Preferably cut patterns with five or six sections are introduced. A section n comprises a short cut line and those between the one mentioned and the following perpendicular cut line located long cut lines and is ended before next following cut line perpendicular thereto. By the following perpendicular cut line is generally about the short cut lines of the following section n+1. In the final section the following perpendicular cut line however corresponds to the final cut line. The number of long cut lines per section n+1 increases compared to the preceding section n while its length decreases. A heating field comprises at least two sections, a first section and a final section. Between these two sections there is optionally a further section, indicated as a center section. The first and the final section of the heating field have in contrast to the center sections a somewhat modified construction. The center sections are similar with respect to their common construction.

In all the sections n a plurality of outer long cut lines branch out from each short cut line and end before the short cut line of the next section n+1 or the final cut line. Within all the intermediate spaces between the long cut lines in the section n, in each case at least a further inner long cut line runs and strikes the short cut line of the next section n+1 or the final cut line of the final section.

The first section is different from the following sections in that it does not start with a short cut line. In the first section a first outer long cut line and a second outer long cut line begin on the inner edge of the connection electrodes and end before a first short cut line of the following section. Between the two outer long cut lines one or more inner long cut lines emanate. The inner long cut lines hit the first short cut line of the following section.

In the final section the cut pattern is ended with a short cut line being hit by the inner long cut lines of this section. However from the final cut line there is no further long cut line.

By this structuring of the conductive coating it is obtained, from connection electrodes up to the final cut line, a cut pattern with a pyramid-shaped construction, having long cut lines meshed with each other in a comb-like manner. Thus the current has to follow the pathway from one connection electrode to the other several windings of the heating pathways. The comb-like cut pattern is constructed in such a way that the pathway lengths and thus also the resistance of the separate heating pathways are identical. In such a way a quite homogenous heating of the heating fields is possible, whereby also the power of the thin layer conductive element is improved. Unexpected is that the areas of the conductive coating, which adjoin the outer long cut lines, do not need to be structured. Also in the other sections of the heating field the surface areas beyond the pyramidshaped basic design are unprepared. Compared with the labyrinth-like cut patterns of prior known art considerable fewer laser cuttings are necessary for structuring of the conductive coating of the inventive thin layer heating element. Thus the thin layer heating element of the invention is considerably more cost effective than the heating element known from the prior art, as the laser time can be considerably reduced. Furthermore the inventive thin layer heating element makes higher heat power possible and new heating element geometries as well.

The number of the long cut lines per section n increases in the section n+1 compared to the preceding section n and the length of the long cut lines is decreased in the section n+1. In a preferred embodiment the number of the long cut lines per section n increases in the section n+1 compared to the preceding section n with two long cut lines and the length of the long cut lines is halved in the section n+1.

The conductive coating is preferably applied on the inner side of one of the two panes, but can also be applied to the inner side of both the panes such that two opposite each other laying heating fields are obtained.

An edge region of the conductive coating is separated from the heating field by a surrounding separation line. The surrounding separation line is in a small distance to the pane edge, such that a small edge region is obtained, which preferably has a width of from 0.5 cm to 2 cm. Thus the edge region is electrically isolated. In this way a corrosion of the conductive coating in the heating field is prevented, as a corrosion starting at the outer edge cannot continue past the surrounding line.

As the number of the long cut lines per section n is increased in every section n+1, while the distance of adjacent long cut lines are the same, also the length of the short cut lines has to be increased with increasing distance from the connection electrodes.

The cut pattern of the thin layer heating element is preferably mirror symmetrical over its longer center line. As a longer center line is that center line indicated which is parallel to the long side of the thin layer heating element. By this symmetry it is made safe that the heating pathways have a constant area. Thus a constant current density is obtained along the whole coating. At the same time the number of laser cuts will be minimized too, which is necessary for production of the cut pattern. However also a pyramid-shaped cut pattern is conceivable which has no mirror symmetry along the center line.

With very large thin layer heating elements having only one cut pattern the outer heating pathway will be too long, and the heating power will drop in this region. Particularly with broad and high heating elements this is the case. To be able to avoid such a loss of heating power several cut patterns can be introduced in the conductive coating. Preferred is to introduce two cut patterns whose long cut lines are parallel to each other and to the long side of the thin layer heating element. In such a way two mirror symmetrical small heating fields are obtained on the thin layer heating element, the outer heating pathway of which has an adequate length such that a good heating power is secured. However, also a mirror symmetrical arrangement with three or more cut patterns is conceivable.

With thin layer heating elements having a plurality of cut patterns, adjacent cut patterns have a common connection electrode of the same polarity which is situated between the cut patterns at the short side of the thin layer heating element. The connection electrodes of opposite polarity are situated above or below the cut pattern also at the short side of the thin layer heating element.

The final cut line in the final section of the heating field may as well coincide with the surrounding separation line. Such a cut pattern is selected above all in large heating areas with a plurality of cut patterns. Thus the outer heating pathway is prolonged whereby it is possible to have a regular heating also with a plurality of cut patterns per thin layer heating element.

The heating pathways between the connection electrodes with opposite polarity have in all the sections of the inventive thin layer heating element the same way length and thus the same resistance. Thereby also the outer heating pathways are passed of the same value of current as the inner heating pathways. In such a case an equivalent heating can be obtained in all conductive areas and thus a higher power of the thin layer heating element is secured.

The first and second panes of the thin layer heating element include lime-sodium-glass, quartz glass and/or boron-silica glass. Preferred is the use of float glass. The glass panes are with advantage thermally prestressed.

The first and second panes of the thin layer heating element have a thickness of from 1 mm to 20 mm. Preferably panes having a thickness of 2 through 8 mm are used.

The laminating film comprises polyvinyl-butyral, ethylene-vinyl acetate, polyurethane, and/or mixtures and/or copolymers thereof. Preferred is the use of polyvinyl-butyral.

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 layer heating element may include silver, gold, copper, indium, tin, zinc and/or mixtures and/or oxides and/or alloys thereof, as well as TCO layers (transparent conductive oxide) such as for instance indium tin oxide (ITO). Preferred is the use of silver coatings of several separate layers of silver. For securing a high transparency of the thin layer heating element a mirroring of the silver layer can be made by silicon nitride. The conductive coating is thermally high loadable and thus it can be attached to the surface even before the pre-stressing of the glass panes. The conductive coating is preferably attached by the method of vapor phase deposition, for instance by chemical vapor phase deposition (CVD, chemical vapor deposition) or physical vapor phase deposition (PVD, physical vapor deposition). Especially preferred is the method of sputtering, such as for instance magnetron sputtering. By this method the metal layer can be very smoothly deposited onto the surfaced of the glass pane.

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

The conductive coating has to its disposal a surface resistance of from 0.5 Ω to 15 Ω per square, preferably 1 Ω to 10 Ω per square, more preferred 2 Ω to 7 Ω per square. The surface resistance of the coating has to be regulated such that the thin layer heating element when working got a maximum temperature of from 80 °C to 90 °C, as is determined in DIN EN 60335. By this temperature restriction it is excluded that persons will be burned when being in touch with the thin layer heating element. The larger thickness and conduction cross section respective of the conductive coating the smaller is the surface resistance. With smaller surface resistances higher current values will appear at the same voltage, whereby higher powers are obtained. However, higher current values bring about a higher temperature of the thin layer heating element. The maximum possible powers are however restricted by the temperature restriction of from 80 °C to 90 °C. Since the current value is dependent of the resistance and of the introduced voltage as well thin layer heating elements with different surface resistance are produced around the world, which are adapted to the local line voltages. For the US market with line voltages of 110 V thin layer heating elements with smaller surface resistances are produced than for the European market with line voltages of generally 230 V.

The cut pattern of the conductive coating is produced by lasering, etching and/or ablation. The lasering is obtained with a wave length of from 300 mm to 1300 mm. The wave length used depends on the type of coating. As a laser source a pulsed semiconductor laser is preferred to be used.

Within the region of the cut lines at least 80 weight%, preferably at least 90 weight% of the metal coating is removed from the glass surface.

Contrary to the point or circle shaped connection electrodes known from the prior art the inventive thin layer heating element has two or more connection electrodes with an elongated shape. They are to be found at the short side of the thin layer heating element and have a direction parallel to that short side.

The connection electrodes can be introduced on the pane before as well as after the removal of the conductive coating. Preferably the connection electrodes are introduced after the removal of the conductive coating. It is made by an electrically conductive metal paste on the inner pane side and is baked in connection therewith. The connection electrodes are then to be found on the same pane side as the electrically conductive coating, and by baking of the metal paste a permanent electrical contacting is secured between the connection electrodes and the conductive coating. The metal paste preferably includes silver, gold, platinum, palladium, copper, nickel, manganese, iron and/or mixtures or alloys thereof, especially preferred is silver. The connection electrodes are connected to a power source through electrical cables.

Furthermore the invention comprises a method for producing of a thin layer heating element with pyramid-shaped laser cut pattern. In a first step a conductive coating is applied on a first pane. Preferably the conductive coating is applied on the pane by a PVD method. In the conductive coating is then a pyramid-shaped cut pattern introduced by lasering, the long cut lines thereof are comb-like meshed with each other. On the short side of the first pane there are two or more connection electrodes applied by baking of an electrically conductive metal paste. The connection electrodes are applied as elongated strips in parallel to the short side of the first pane and make contact with the conductive coating.

On the inner side of the first pane, carrying the conductive coating and the connection electrodes, a lamination film and on the lamination film a second pane are applied in the next step. This arrangement of the first pane with conductive coating and connection electrodes, lamination film and the second pane are at first pre-evacuated and finally laminated in the autoclave for 2.5 hours at 80 °C to 135 °C and 7 bar to 13 bar.

Furthermore the invention comprise the use of a thin layer heating element as a functional and/or decorative individual item and/or as a built-in component in furniture, appliances, buildings and vehicles. Preferably the inventive thin layer heating element is introduced as a freestanding or wall mounted heater in living areas, as a heatable fagade glacing or as a heatable vehicle window pane, watercraft window pane or aircraft window pane.

Specific embodiments of the inventive thin layer heating element with pyramid-shaped laser cut pattern comprise a thin layer heating element with rounded corners up to elliptic shaped thin layer heating elements. As the long side of the thin layer heating element, to which the long cut lines are parallel, is then the tangent defined which lies close to the long heating element side. Other embodiments of the inventive thin layer heating element with pyramid-shaped laser cut pattern involve a break sensor at the edge strips of the thin layer heating element. In that case the edge strip is separated in different regions. In one of the regions a slight voltage is applied. Thus a defect of the heater element can be detected through the lapse of the voltage in this region. Other embodiments of the thin layer heating element with pyramid-shaped laser cut pattern comprise thin layer heating elements with measuring current sections for temperature measuring at different parts of the heater element. In a further embodiment of the inventive thin layer heating element the connection electrodes are brought together to a bus bar. This embodiment is in first hand advantageous by very broad thin layer heating elements having more than 3 connection electrodes.

The invention will be further explained below in connection with the drawings. The drawings do not restrict the invention in any way, and

Fig. 1 a shows a schematic view of the inventive thin layer heating element with a pyramid-shaped laser cut pattern,

Fig. 1 b shows an enlarged section of the pyramid-shaped laser cut pattern of the inventive thin layer heating element,

Fig. 2 shows a schematic view of the inventive thin layer heating element with exemplifying depicted heater current pathways,

Fig. 3 shows a schematic view of the inventive thin layer heating element with two pyramid-shaped laser cut patterns,

Fig. 4 shows a schematic cross section of the inventive thin layer heating element,

Fig. 5 shows a flow chart for production of the inventive thin layer heating element,

Fig. 6 shows two schematic views of the thermographs of a thin layer heating element according to prior known art and

Fig. 7 shows a schematic view of a thermograph of the inventive thin layer heating element.

Fig. 1 a shows a schematic view of the inventive thin layer heating element 1 with pyramid-shaped laser cut pattern. The thin layer heating element 1 comprises a first pane 2.1 onto 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 layer heating element 1 has two long sides 8 and two short sides 7 being perpendicular to each other. The two connection electrodes 4.1,4.2 have a lengthy shape and are arranged at a short side 7 of the thin layer heating element I. The connection electrodes make contact with the conductive coating 3 such that a voltage, supplied to the connection electrodes 4.1,4.2, also is to be found in the coating. A cut pattern 13 is introduced in the conductive coating 3. In these regions the conductive coating 3 is removed from the surface of the first pane 2.2, such that these regions are electric isolated. By this structuring heat current pathways 12.n are obtained in the conductive coating 3. These heat current pathways 12.n will be passed by a current when a voltage is applied to the connection electrodes 4.1,4.2. The cut pattern 13 of the conductive coating 3 is separated in long cut lines 5 and short cut lines 6, whereby by the long cut lines 5 it is distinguished between outer long cut lines 5.1 and inner long cut lines 5.2. All the long cut lines 5 are parallel to the long side 8 of the thin layer heating element 1, while the short cut lines 6 are arranged in parallel to the short side. Thus the long cut lines 5 and the short cut lines are perpendicular to each other. The heating field 10 obtained by the structuring is separated in several sections 11 .n, which are defined by the short cut lines 6. At least a first section 11.1 and a final section 19 are necessary and optional there can be several center sections 11.2 between them. In the present embodiment there are three center sections 11.2a, 11.2b, 11.2c. In the first section 11.1 there are a first outer long cut line 5.1 a and a second outer long cut line 5.1 b at the inner edges of the connection electrodes 4.1,4.2. Between these two outer long cut lines 5.1a, 5.2b there is a first inner long cut line 5.2a. Thus the total number of long cut lines 5 of the first section 11.1 amount to three.

In each one of the following sections 11 .n the number of long cut lines 5 per section 11 .n is increased with two, while the length of the long cut lines 5 is halved. The length of the short cut lines 6 is increased from the first section 11.1 up to the final section 19. The first outer long cut line 5.1 a and the second outer long cut line 5.1 b end in front of the first short cut line 6.1 of the second section II, 2a, while the first inner long cut line 5.2a hits the first short cut line 6.1. In the second section 11.2a at the first short cut line 6.1 three outer long cut lines 5 are established, which end in front of the short cut line 6 of the next following section.

In the interspaces of the outer long cut lines 5 there is a further inner long cut line 5, which hits the short cut line 6 of the following section. The two following center sections 11.2b, 11.2c are constructed by analogy with the first center section 11,2a. The final section 19 is defined of a final cut line 9 hit by those in this section going long cut lines 5. By such an arrangement of the separate cut lines 5, 6 the long cut lines 5 of the pyramid-shaped cut pattern 13 are meshed with each other in a comb-like manner. This unusual cut pattern 13 results in surprising very homogenous heat power with at the same time reduced number of laser cut lines. Preferably the cut pattern 13 has a mirror symmetry along the longer center line 16. At the edge of the thin layer heating element 1 there is a smaller edge region 14 separated from the heating field 10 by a surrounding separation line 15. Thereby the edge region 14 is electrically isolated.

Fig. 1 b shows an enlarged section of the pyramid-shaped laser cut pattern of the inventive thin layer heating element. The cut pattern described in Fig. 1a comprises a number of cut lines which mainly can be inserted in the two groups of short cut lines 6 and the long cut lines 5. The long cut lines 5 are in turn separated in outer long cut lines 5.1 and inner long cut lines 5.2. The short cut lines 6 proceed in parallel to the short side 7 of the thin layer heating element 1, while the long cut lines are arranged in parallel to the long sides 8. Most long cut lines 5.1 originate from each one of the short cut lines 6, whereby an inner long cut line 5.2 proceeds in the spaces between two outer long cut lines 5.1.

Fig. 2 shows a schematic view of the inventive thin layer heating element 1 with exemplified shown heat current pathways. The thin layer heating element 1, having a first pane 2.1, a lamination film 17, a second pane 2.2, long sides 8 and short sides 7, comprises a conductive coating 3 applied to the surface as well as two connection electrodes 4.1,4.2 at the short side 7. On the conductive coating 3 there is a cut pattern 13 applied in analogy with the cut pattern described in Fig. 1, whereby the long cut lines 5 proceed in parallel to the long side 8 of the thin layer heating element 1 and the short cut lines 6 as well as the final cut line 9 proceed perpendicular thereto. In such a way a heating field 10 is obtained on the conductive coating 3. A smaller edge region 14 is separated and electrical isolated from the heating field 10 by a surrounding separation line 15. In the heating field 10 different heat current pathways 12.n are obtained by the structuring of the conductive coating 3, from which a first heat current pathway 12.1, a center heat current pathway 12.2 and a final current pathway 12.3 are shown as examples. The rest of the heat current pathways 12.n are not shown due to the clearness. The current flows through the heat current pathways 12.n always from a negative connection electrode 4.2 to a positive connection electrode 4.1. All of the heat current pathways 12.n have the same length and thus the same resistance, such that all of the heat current pathways 12.n are equally heated and the thin layer heating element 1 has a very homogenous heat effect.

Fig. 3 shows a schematic view of the inventive thin layer heating element 1 with two pyramid-shaped laser cut patterns. The thin layer heating element 1 comprises a first pane 2.1, a laminating film 17 and a second pane 2.2 as well as a long side 8 and a short side 7. The electrical conductive coating 3 applied to the first pane 2.1 is separated in heat current pathways 12.n by a first cut pattern 13.1 and a second cut pattern 13.2. The first cut pattern 13.1 and the second cut pattern 13.2 are mirror symmetrical to each other over the longer center line 16.

On a short side 7 of the thin layer heating element 1 there is a common negative connection electrode 4.2 applied between the two cut patterns 13.1, 13.2. Above and below the cut patterns 13.1, 13.2 there are a first positive connection electrode 4.1 and a second positive connection electrode 4.3 also arranged at the short side 7 of the thin layer heating element 1. The two cut patterns 13.1, 13.2 comprise long cut lines 5 and short cut lines 6, which are placed in a way analogues with the pattern described in Fig. 1. Thus all the long cut lines 5 are in parallel to the long side 8, while the short cut lines 6 proceed perpendicularly thereto. An edge region 14 of the thin layer heating element 1 is separated from the heating field 10 by a surrounding separation line 15, whereby the surrounding separation line 15 acts as a final separation line of the two cut patterns 13.1,13.2.

Fig. 4 shows a schematic cross section of the inventive thin layer heating element 1. On the first pane 2.1 there is a conductive coating 3 applied. In a direct contact with the conductive coating 3 there are at least two connection electrodes 4.1,4.2 attached. The connection electrodes 4.1,4.2 are connected to the current source by electrical connections 18. A laminating film 17 is applied on the conductive coating 3. The arrangement is covered by a second pane 2.2.

Fig. 5 shows a flow chart for the method of production of the inventive thin layer heating element 1. In a first step a conductive coating 3 is introduced on the first pane 2.1. Thereafter a pyramid-shaped cut pattern 13 is introduced with a laser in the conductive coating 3, whereby the long cut lines 5 are meshed with each other in a comb-like manner. On the short side 7 of the first pane 2.1 there are two or more connection electrodes 4.1,4.2, 4.3 applied by baking of an electrically conductive metal paste in such a way that the conductive electrodes 4.1,4.2, 4.3 are in contact with the conductive coating 3. A laminating film 17 is introduced on the first side of the first pane 2.1 which carries the conductive coating 3 and the connection electrodes 4.1,4.2, 4.3 and a second pane 2.2 is placed on the laminating film 17. The arrangement of the 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 the autoclave.

Fig. 6 shows a schematic view of two thermographs of a thin layer heating element according to the prior known art. The thermographs show a temperature decrease from the inner region of the thin layer heating element out to the outer edge. In the inner region there are several extended hot spots I. These so called hot spots I are regions with clearly increased temperature compared to the average temperature. Next to the hot spots there is a region of middle temperature II with a relatively homogenous temperature distribution. The edge of the heating element is a colder region III, in which the temperature is below the average temperature. Some such colder regions III are also to be observed in the inner of the heating element. The absent homogeneity of the known thin layer heating element is quite obvious.

Fig. 7 shows a schematic view of a thermograph of the inventive thin layer heating element. In the inner of the thin layer heating element there are some very restricted hot spots I, in which the temperature is above the average temperature. In the inner of the thin layer heating element there are some colder regions III as well. The temperature is decreasing in the direction of the edge of the heating element, whereby the inventive thin layer heating element surprisingly has only a small colder region III at the edge region.

The inventive thin layer heating element has, as shown by a comparison of the thermographs in Fig. 6 and Fig. 7, a much more high homogeneity than the models known per se.

Below the invention be explained in more detail in connection with the thermographs of the inventive thin layer heating element and a thin layer heating element according to prior known art, the maximum effects and the production times of the two thin layer heating elements.

In two experiment series the maximum effect, the production time and the homogeneity of the inventive thin layer heating element were compared with a thin layer heating element according to prior known art. By both the experiment series a thin layer heating element comprising a first pane 2.1 with conductive coating 3, a laminating film 17 and a second pane 2.2 was used. The two longer side edges of the thin layer heating element 1 were defined as long sides 8 and the two shorter side edges as short sides 7. As a first pane 2.1 and as a second pane 2.2 float glass was used each one having a thickness of 6 mm. As a laminating film a PVB film with a thickness of 0.38 mm was used. The conductive coating 3 was applied on the first pane 2.1 through magnetron sputtering. The connection electrodes 4.1,4.2 were obtained by introduction and baking of a silver paste. The structuring of the conductive coating 3 was made by laser treatment. On the first pane 2.1 having treated conductive coating 3 and connection electrodes 4.1,4.2 a laminating film 17 was applied and the lamination film 17 was covered by a second pane 2.2. The arrangement was laminated during 2.5 hours at 80 °C to 135 °C and 7 bar to 13 bar. The homogeneity of the thin layer heating element was examined in that the colder edge regions in different heating element sections viewed in the thermographs were measured and put in relation to the total width of the heating element. The corresponding measurements were made in the length parts 1/8, 1/4,1/2 , and 3/4 with reference to the total length of the long side 8 and started at the lower short side 7 of the thin layer heating element. The values mentioned for the thin layer heating element according to prior known art correspond to the average values of the two in Fig. 6 schematically shown thermographs.

The thin layer heating element was connected to a current source and after having reached a constant temperature (about 20 minutes) at maximum power a thermograph (schematic views in Figs. 6 and 7) was taken of the thin layer heating element by an infrared camera. To secure sufficient detail fidelity of the infrared pictures the recordings were made at a plurality of sections. The separate pictures were then put together to a total picture, a) Example 1: Maximum power, production time and homogeneity of the inventive thin layer heating element

The inventive thin layer heating element 1 having a size of 400 mm x 1800 mm had two elongated connection electrodes 4.1,4.2 at the short side 7 of the thin layer heating element 1. In the conductive coating 3 of the thin layer heating element 1 a pyramid-shaped cut pattern 13 was applied, the long cut lines 5 of which were meshed with each other in a comb-like manner. For taken of the thermograph (Fig. 6) the electrical connections 18 arranged on the connection electrodes 4.1,4.2 were connected to a current source. In such a way a voltage of 230 V was applied to the heating field 10. b) Comparative example 2: Maximum power, production time and homogeneity of the thin layer heating element according to prior known art The thin layer heating element according to prior known art was of Model Thermovit Elegance (Saint-Gobain Glass Solutions) having a size of 400 mm χ 1800 mm and had two rounded connection electrodes. The cut lines which extend from one connection electrode to other ones, extended labyrinth-like over the whole conductive coating by analogy with the described prior known art cut patterns (e.g. DE-B3-102 59 110 and WO 2012/066 112). For taken of the thermograph the electrical connections were connected to a current source and a voltage of 230 V was applied.

Table 1 shows comparably the maximum power of the inventive thin layer heating element and of the thin layer heating element known per se as well as the saving of production time of the laser process.

Table 2 shows the percentage parts of cold edge regions on the total cross section in different length sections of the thin layer heating element.

By the production of the inventive thin layer heating element the time used for the laser process can be halved compared to a thin layer heating element according to the prior known art (see Table 1). The total length of all the laser cuts is by the inventive thin layer heating element about 50% shorter than up to now according to prior known art. Thus the shortening of the laser cuts results also to a corresponding time saving. Since the laser process is the slowest step of a series of production steps therefore the whole production process is accelerated. The time consumption of the step is also decisive for the costs of the production process as the working by laser is long and consequently expensive. Therefore an acceleration of the step involve a substantial cost saving. In addition to these economical advantages the inventive thin layer heating element also offer an essentially higher heating power (see Table 1). The pyramid-shaped cut pattern with long cut lines being meshed with each other in a comb-like manner is especially suited for narrow high heating elements. By such forms the thin layer heating element known per se gives only an insufficient heating power, since the outer heating current pathway has a too high resistance. Thus all the heating current pathways will not be passed by an equal current and the maximum power is reduced. Of that reason there are in-homogeneities in the heating power as is clearly shown in the thermographs (schematic views, see Fig. 6 and Fig. 7). The thermographs show a drop in temperature from the inner region out to the outer edge of the thin layer heating element. In the inner region of the heating element both the two thin layer heating elements have so called hot spots I, which by the known thin layer heating element has a further extension. After the hot spots I in the inner of the heating element follow a region of middle temperature II with a relative homogenous temperature distribution. In the edge region of the heating element there is a colder region III in all of the thermographs. A comparison of the thermographs of the inventive thin layer heating element and the prior known thin layer heating element it will already at the first glance be obvious that the inventive thin layer heating element has a higher homogeneity. A more careful evaluation of the part of the cold edge regions on the total cross section confirms this unequivocally (Table 2). The inventive thin layer heating element has over the whole length of its heating element a very small remaining edge part of below 10%. The thin layer heating element of prior known art has, especially in the lower region (length section 1/8, Table 2) a very high edge part of about 34%, which certainly decreases upwards but does not drop below 20%. The complex of problems with failing homogeneity appears especially by long narrow heating elements, since the outer heat current pathway has a too high resistance by the thin layer heating elements according to prior known art. Nevertheless by this particularly narrow high form of the inventive thin layer heating element a surprisingly exceptional high homogeneity can be obtained.

The fact is that a new cut pattern, in spite of reducing the laser cutting provides a homogenous heat power and a maximum power was surprising and unexpected for the expert in the field. The enormous reduction of laser cuts by the inventive thin layer heating element is with respect to a cost reduction of the production process a crucial advantage.

List of reference numbers 1 thin layer heating element 2 panes 2.1 first pane 2.2 second pane 3 conductive coating 4 connection electrodes 4.1 first positive connection electrode 4.2 negative connection electrode 4.3 second positive connection electrode 5 long cut lines 5.1 outer long cut lines 5.1 a first outer long cut line 5.1b second outer long cut line 5.2 inner long cut lines 5.2a first inner long cut line 6 short cut lines 6.1 first short cut lines 7 short side 8 long side 9 final cut line 10 heating field 11 sections 11.1 first section 11.2 center section 11.2a second section 11.2b third section 11.2c fourth section 12.n heat current pathways 12.1 first current pathway 12.2 center current pathway 12.3 final current pathway 13 cut pattern 13.1 first cut pattern 13.2 second cut pattern 14 edge area 15 surrounding separation line 16 longer center line 17 laminating film 18 electrical connections 19 final section I hot spots II areas of middle temperature III colder areas

Claims

A thin film heater (1) comprising at least one disk composite of at least one first disk (2.1), a laminating foil (17), a second disk (2.2), two long sides (8), two short sides (7), one in at least on the inside of the first disc (2.1), flat, electrically conductive coating (3), at least two connecting electrodes (4.1, 4.2, 4.3) on the short side (7) of the thin film heater (1) for contacting the conductive coating ( 3), at least one electrical connection (18) and at least one sectional pattern (13) with heat flow paths (12.n) connecting the connection electrodes (4.1, 4.2, 4.3), wherein a) the sectional pattern (13) comprises long section lines (5.1, 5.2 ) containing outer long section lines (5.1) and inner long section lines (5.2) extending parallel to the long side (8) of the thin film heater (1) and short section lines (6) extending parallel to the short side (7) of the thin film heater (1), (b) there is a heating field (10) formed on the conductive coating (3), it lines (6) are divided into several sections (11.n), where n is an integer> 1, (c) the number of long section lines (5.1, 5.2) per section (11.n) increases in the section (11n) +1) in comparison with the section (11.n) and the length of the long section lines (5.1, 5.2) decreases in the section (ll.n + 1), d) from each short section line (6) of the section (11. (n) a plurality of outer long section lines (5.1) ending before the short section line (6) of the section (ll.n + 1) or a final section line (9) is deleted; (e) at all intervals between two outer long section lines (5.1) ) in the section (11.n), at least one respective inner long section line (5.2) extends and hits the short section line (6) of the section (ll.n + 1) or the final section line (9), and f) in the first section (11.1), respectively, a first outer long section line (5.1a) and a second outer long section line (5.1b) begin at the inner edge of the connecting electrodes (4.1, 4.2) and end before a first short section line (6.1), so that the conductive coating (3) from connection the electrodes (4.1, 4.2) until the final cut line (9) comprise a pyramid shaped cut pattern (13) whose long cut lines (5) are tooth-like with one another.

The thin film heater according to claim 1, wherein the number of long section lines (5.1, 5.2) per section (11.n) of the section (11n + 1) in comparison with the section (11.n) increases with two long section lines (11. n) and halve the length of the long section lines (5.1, 5.2) in the section (ll.n + 1).

Thin film heater according to claim 1 or 2, wherein the conductive coating (3) is arranged on the first disk (2.1) and the second disk (2.2).

Thin film heater (1) according to one of claims 1 to 3, wherein a peripheral region (14) is separated and electrically insulated from the heating field (10) by means of a dividing line (15).

The thin film heater (1) according to any one of claims 1 to 4, wherein the length of the short section lines (6) increases with increasing distance of the associated section (11) from the connecting electrodes (4.1, 4.2).

The thin film heater (1) according to one of claims 1 to 5, wherein the sectional pattern (13) is mirror-symmetrical about its longer centerline (16).

Thin film heater (1) according to one of claims 1 to 6, wherein several cut patterns (13) are arranged on at least one of the two discs (2) such that the long cut lines (5) of both cut patterns (13) are parallel to each other and with the long side (8) of the thin film heater (1) and the arrangement is mirror symmetrical about the longer center line (16) of the thin film heater (1).

The thin film heater (1) of claim 7, wherein adjacent cut patterns (13) comprise a common connection electrode (4.1, 4.2, 4.3) of the same polarity.

Thin film heater (1) according to one of claims 1 to 8, wherein the final cut line (9) corresponds to the circumferential dividing line (15).

Thin film heater (1) according to one of claims 1 to 9, wherein the resistance and path length of the heat flow paths (12.n) between connecting electrodes (4.1, 4.2, 4.3) with opposite polarity are the same in all sections (11).

Thin film heater (1) according to any one of claims 1 to 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.

The thin film heater (1) according to any one of claims 1 to 11, wherein the cut pattern (13) is obtained by removing the conductive coating by means of lasers, etching and / or removal, preferably lasers.

The thin film heater (1) according to one of claims 1 to 12, wherein the connecting electrodes (4.1, 4.2, 4.3) have an elongated shape and are arranged parallel to the short side (7) of the thin film heater (1).

Thin film heater (1) according to one of claims 1 to 13, wherein the connecting electrodes (4.1, 4.2, 4.3) are made before or after depositing the conductive coating (3) by removal and burning of an electrically conductive metal paste on the same disc surface, such as the conductive coating (3).

A method of producing a thin film heater (1) according to claims 1 to 14, wherein m) a cut pattern (13) is introduced into the conductive coating (3) by lasers, n) two or more connecting electrodes (4.1, 4.2, 4.3 ) is applied to one of the short sides (7) of the first disc (2.1) by the burning of an electrically conductive metal paste, o) a laminating foil (17), and to at least one second disc (2.2) on the laminating foil (17); is laid on the surface of the first disc (2.1) which carries the conductive coating (3) and the connecting electrodes (4.1, 4.2, 4.3), and p) the device is autoclaved.

Use of a thin film heater (1) according to one of claims 1 to 15 as a functional and / or decorative single piece and / or as an integral part of furniture, utensils, buildings and vehicles, preferably as freestanding or wall-mounted heaters in living rooms, as a facade glass element which can be heated, or as a vehicle window, ship window or heated air window.