Heating element comprising films

[0027] The invention relates to a heating element comprising at least one substrate equipped with a thin layer stack comprising layers suitable for heating. The layer suitable for heating has an electrical sheet resistance of between 20 and 200 ohms per square unit. A layer suitable for heating allows the glazing to be defogged/deiced or the room to be heated. The stack also includes two non-metallic dielectric layers on either side of the layer suitable for heating. These non-metallic dielectric layers have an anti-reflection function. The heating element also includes two conductive current collectors adapted to receive an electrical voltage, to which the layer adapted to be heated is electrically connected to be heated. The layer suitable for heating is intact, ie it has not been processed by etching. Consequently, no areas are removed from this layer, and no geometrical features are etched in the layer suitable for heating, which would increase the effective resistance of the glazing.

[0028] Thus, the layer suitable for heating has an electrical sheet resistance between 20 and 200 ohms per square unit and does not need to be etched. This simplifies the manufacture of the heating element. Furthermore, the power dissipated is now controlled and compatible with conventional electrical systems. The invention thus makes it easy to install a heating element according to the invention in an electric vehicle or to connect it to the mains.

[0029] figure 1 A cross-sectional view of a heating element according to one embodiment of the invention is shown.

[0030] The heating element comprises a substrate 1 on which is deposited a thin layer stack comprising a layer 3 suitable for heating. The thin layer stack is deposited, for example, by sputtering, in particular by means of a magnetic field (magnetron sputtering).

[0031] The substrate 1 is made, for example, of organic or inorganic glass. It is, for example, transparent, especially when it is used in applications that require seeing through, such as in automotive or architectural glazing. The substrate 1 is preferably but not limited to a glass plate.

[0032] The layer 3 suitable for heating is made of a metal such as niobium, molybdenum, nickel, chromium, tin, zinc, tantalum, hafnium, titanium, tungsten, aluminum or copper or an alloy of one of them.

[0033] The thin layer stack also includes two non-metallic dielectric layers 4 , 5 . A layer 3 suitable for heating is located between two non-metallic dielectric layers 4 , 5 . These non-metallic dielectric layers 4, 5 are made of Si 3 N 4 , SnZnO, SnO 2 Or made of ZnO. These layers 4, 5 have an anti-reflection function, which improves the visibility through the heating element equipped with the layer 3 suitable for heating, especially when the substrate is made of glass. The non-metallic dielectric layers 4 , 5 are deposited, for example, by sputtering, in particular by means of a magnetic field.

[0034] The stack of thin layers optionally comprises at least one barrier layer (not shown) between the layer 3 suitable for heating and at least one of the non-metallic dielectric layers 4 , 5 . The barrier layer may thus be a lower layer of the layer 3 suitable for heating, thus being located between the substrate and the layer 3 suitable for heating, and/or an upper layer of the layer 3 suitable for heating. The one or more barrier layers are very thin. If necessary, they protect the layer suitable for heating 3 from possible degradation during the deposition of the non-metallic medium layer 5 on top of the layer suitable for heating 3 . They also protect the layer 3 suitable for heating during high-temperature heat treatments, such as during bending and/or tempering, for example in order to prevent oxidation of said layer 3 . The one or more barrier layers are made, for example, of NiCr, titanium or aluminum. The one or more barrier layers are deposited, for example, by sputtering, in particular by means of a magnetic field.

[0035] The layer 3 suitable for heating has a thickness between 2 and 30 nm. This thickness range is technically easy to manufacture and allows to obtain a layer with controlled thickness over the entire area of ​​the glass pane. When the heating element is used in glazing applications with the restriction that the light transmission must be at least 70% and even at least 75%, i.e. especially for windshields and front side windows, the thickness of the layer 3 suitable for heating is between 2 and 8 nm between.

[0036] In order to obtain a light transmittance of at least 75%, niobium and molybdenum are perfectly suitable materials for the layer 3 suitable for heating, so that a layer 3 with a thickness between 2 and 8 nm has a resistance between 20 and 200 ohms per square unit Electrical sheet resistance for layers suitable for heating.

[0037] In the group consisting of niobium, molybdenum, nickel, chromium, tin, zinc, tantalum, hafnium, titanium, tungsten, aluminum, copper and their alloys when the heating element is not used in an application with light transmittance limitations The material is suitable for the layer 3 suitable for heating such that a layer having a thickness between 2 and 30 nm has an electrical sheet resistance for the layer suitable for heating of between 20 and 200 ohms per square unit.

[0038] The heating element also includes two conductive current collectors (not shown) positioned near two opposing edges of the heating element. The layer 3 suitable for heating is electrically connected to these conductive current collectors. The conductive current collector is the terminal for supplying voltage to the layer 3 suitable for heating. In the case of a heated windshield, electrically conductive current collectors are placed, for example, on the top and bottom of the windshield.

[0039] In a first variant, the heating element preferably comprises a second substrate 2 and an intermediate layer 6 placed between the two substrates 1 , 2 so as to form a stack. In this configuration, the layer 3 suitable for heating and the non-metallic dielectric layers 4, 5 are preferably deposited on the side of the substrate 1 facing the intermediate layer 6 and not oriented towards the outside of the heating element, in order to protect the thin layer stack from subject to external damage. The intermediate layer is for example made of standard PVB (polyvinyl butyral) or any material suitable for acoustic damping. This material, suitable for acoustic damping, is then preferably placed between two standard PVB layers.

[0040] In this first variant, the second substrate 2 is made, for example, of organic or inorganic glass. It is, for example, transparent, especially when it is used in applications that require seeing through, such as in automotive or architectural glazing. The substrate 2 is preferably but not limited to a glass plate.

[0041]The heating element according to this first variant can be used as a glazing for motor vehicles, especially electric vehicles. When the glazing is a windshield or front side windows, it faces visibility limitations. In fact, the light transmittance must be at least 70%, or even at least 75%, to meet the mandatory standards. This light transmittance is achieved by a heated glazing as defined above. On the contrary, when the glass window is a rear side window, a rear window or a sunroof, it is not subject to any light transmittance limitation.

[0042] The heating element according to this first variant can also be used as a building glazing, for example as a partition wall between two rooms, or for an external curtain wall of a building, in combination with a third glass window separated from the heating element by a gas sheet. substrate. The third substrate is made, for example, of organic or inorganic glass. The third substrate is, for example, transparent.

[0043] The heating element according to this first variant can also be used as an electric heater for buildings.

[0044] In a second variant, the heating element comprises at least the second substrate 2 . The substrates 1, 2 are separated in pairs by gas lamellae in order to form thermally insulating multiple glazing. The layer 3 suitable for heating is preferably placed facing the gas sheet and not oriented towards the outside of the heating element in order to protect the stack of sheets from external damage.

[0045] The heating element according to this second variant can also be used as building glazing.

[0046] The invention thus also relates to glazing for electric vehicles, in particular windshields or front side windows, which must have a light transmission of at least 70% or even at least 75%, or even rear side windows, rear windows or even sunroofs, which Not subject to any light transmittance restrictions. The invention also relates to an electric vehicle having such a glazing. The invention also relates to building glazing or electric heating for buildings.

[0047] In the case of glazing for vehicles or buildings, or in the case of electric heating for buildings, the electrically conductive current collectors are connected in a known manner to the electrical system and receive voltage from this electrical system. The layer suitable for heating is heated when a voltage is applied to it. With the present invention, conventional electrical systems can be used.

[0048] In the case of automotive or building glazing, the purpose of the layer suitable for heating is to defog and/or deice the glazing.

[0049] In the case of heating, the purpose of the layer suitable for heating is essentially domestic heating, but it can also be used for demisting purposes, especially when it is used in bathrooms.

[0050] The heating element according to the invention comprises the following layers:

[0051] Glass/Si 3 N4/Nb/Si 3 N 4 /PVB/glass

[0052] and have the following thicknesses in order:

[0053] Material Glass Si 3 N 4 Nb Si 3 N 4 PVB Glass thickness 2 mm 45 nm 3 nm 65 nm 0.76 mm 2 mm

[0054] Has an electrical sheet resistance of 150 ohms per square unit. In this example, the layer suitable for heating is made of niobium and has no barrier layer. A 75 cm high heating element, supplied with 220V, emits 575 W/m 2 power per unit area and has a light transmittance of 70%. Such heating elements can be used as windshields or front side windows of electric vehicles.

[0055] Likewise, the heating element according to the invention comprises the following layers:

[0056] Glass / Si 3 N 4 /Al/Cu/Al/Si 3 N 4 /PVB /glass

[0057] and have the following thicknesses in order:

[0058] Material Glass Si 3 N 4 Al Cu Al Si 3 N 4 PVB Glass thickness 2 mm 33 nm 1.3 nm 5.6 nm 1.3 nm 33 nm 0.76 mm 2 mm

[0059] Has an electrical sheet resistance of 40 ohms per square unit. In this example, the layer suitable for heating is a copper layer and the aluminum layer is a barrier layer. A 75 cm high heating element, supplied with 220V, emits 2150 W/m 2 power per unit area and has a light transmittance of 70%. Such heating elements can be used as windshields or front side windows of electric vehicles.

[0060] Likewise, the heating element according to the invention comprises the following layers:

[0061] Glass / Si 3 N 4 /Ti/Nb/Ti/Si 3 N 4 /PVB/glass

[0062] and have the following thicknesses in order:

[0063] Material Glass Si 3 N 4 Ti Nb Ti Si 3 N 4 PVB Glass thickness 2 mm 42 nm 0.5 nm 15 nm 0.5 nm 54 nm 0.76 mm 2 mm

[0064] Has an electrical sheet resistance of 23 ohms per square unit. In this example, the layer suitable for heating is a niobium layer and the titanium layer is a barrier layer. A 1 m high heating element, supplied with 220V, emits 2100 W/m 2 The power per unit area and has a light transmittance of 27%. Such heating elements can be used as rear side windows, sunroofs or rear windows of electric vehicles, or even as building glazing, or as electric heaters for buildings.

[0065] Likewise, the heating element according to the invention comprises the following layers:

[0066] Glass / Si 3 N 4 /NiCr/Al/NiCr/Si 3 N 4 /PVB /glass

[0067] and have the following thicknesses in order:

[0068] Material Glass Si 3 N 4 NiCr Al NiCr Si 3 N 4 PVB Glass thickness 2 mm 50 nm 1nm 5.5 nm 1nm 50 nm 0.76 mm 2 mm

[0069] Has an electrical sheet resistance of 80 ohms per square unit. In this example, the layer suitable for heating is an aluminum layer and the NiCr layer is a barrier layer. A 1 m high heating element, supplied with 220V, emits 605 W/m 2 power per unit area and has a light transmittance of 50%. Such heating elements can be used as rear side windows, sunroofs or rear windows of electric vehicles, or even as building glazing, or as electric heaters for buildings.