RU2776075C1 - Multilayer glazing, including a transparent base with a heating layer containing variable-width current lines - Google Patents

Abstract

FIELD: technical glassware.

SUBSTANCE: invention relates to multilayer glazing consisting of several rigid transparent bases glued together in pairs by means of an intermediate adhesive layer. At least one of these bases is covered with an electrically conductive layer. The zone of this transparent base has four opposite edges in pairs. The first and second conductive busbars are located along two opposite edges. The electrically conductive layer has current lines to conduct electric current between the busbars. All current lines have a variable width. The invention also relates to a method for manufacturing such glazing and its application, in particular, in aviation.

EFFECT: group of inventions provides uniform heating of the glazing.

15 cl, 2 dwg, 3 tbl

Description

[0001] Vehicle window panes (such as aircraft, trains, helicopters, ships, motor vehicles, etc.) and, in some cases, building glazing may be provided with heating features built into the glazing to prevent or eliminate, depending on depending on the situation, fogging on the inside or icing on the outside.

[0002] Heating is characterized by a specific power (W/m ² ), which is adapted to the specific needs of each application.

[0003] The heating system consists, for example, of filaments screen-printed on single-layer glazing, or inserted into the intermediate adhesive layer of laminated glazing, or formed of transparent conductive layers (doped oxides: tin-doped indium oxide (ITO) from the English Indium Tin Oxide ), AZO (from the English Aluminum Zinc Oxide, zinc oxide doped with aluminum), SnO ₂ :F, or from metals such as silver, or possibly from a multilayer package with the same or different layers), which allows heating due to Joule effect. In both cases, the heating system is powered by voltage powered electrodes available on the vehicle or in the building.

[0004] Glasses with heating layers are obtained by cutting and possibly molding glass already containing such a layer, or by later (after cutting) depositing a layer on shaped glass. By "glass" is meant here preferably any mineral glass, as well as a rigid transparent base made of a polymeric material, a typical example of which is polymethyl methacrylate (PMMA).

Since a non-rectangular shape cannot be heated uniformly, in the case of a layer having a uniform electrical conductivity, two strategies are implemented:

- the gradient of electrical conductivity, usually due to the gradient of the thickness of the electrically conductive layer, such as a conductive metal oxide (usually ITO); significant changes in the layer thickness make it possible to limit the current density in some parts of the heating surface; the more complex the shape, the more pronounced the thickness gradient and the more difficult it is to implement from an industrial point of view;

- lines of ablation in the electrically conductive layer, called lines of flow separation or, more commonly, current lines, as described in patent EP1897412-B1, which direct the flow of electric current; this solution gives good results in terms of homogeneity only if the current leads are parallel and have the same length (minor deviations are allowed).

[0005] These two strategies can be used in combination.

[0006] The means used to create a gradient in the thickness of the electrically conductive layer can be difficult to control, and the electrical impedance of the layer across the entire area of the glazing can vary considerably. For all window glass at a constant electric current voltage U between the current leads (tires), the rated total power is equal to U ² /R, where R means the impedance of the electrically conductive layer; if the impedance R is too low, it can lead to too high power (too much energy consumed by the heating system) and in the extreme case the product will be rejected because it no longer meets the required tolerances.

[0007] In addition, when the heated glazing has a complex shape and when current lines are created on the electrically conductive layer to guide the electric current and to some extent equalize the local heating power density, power density inhomogeneities may still be maintained over the entire area of the glazing; in particular, in the region of sharp corners of the glazing surface, the heating power density is lower and not high enough. With a constant electric current i on the entire conductive strip between two current lines, the power P dissipated locally is equal to R⋅i ² , and the power density Ps is equal to P/S (for example, in W/dm ² ), where S is the area between two current lines.

[0008] Thus, the invention is directed to the development of heated glazing, in which the rated power does not exceed a certain maximum value, and the power density of which is controlled equalized over the entire area of the glazing, and in particular where the power densities are minimal, for example, in some corner zones, they rise.

[0009] This object has been achieved by the present invention, which thus relates to a laminated glazing consisting of several rigid transparent bases connected to each other in pairs by means of an intermediate adhesive layer, at least one of these bases is covered with an electrically conductive layer, wherein one zone of this transparent base has four pairwise opposite edges, and the first and second conductive busbars are located along two opposite edges, the electrically conductive layer has streamlines for conducting electric current between the busbars, and the glazing is characterized in that all streamlines have a variable width.

[0010] Creating current lines of variable width allows better control of the ohmic resistance of the layer and better control of the power consumed by the layer.

[0011] The use of a laser with a scanner makes it possible, for example, to change the width of the streamlines obtained by ablation.

[0012] The measurement of the ohmic resistance of the heating layer allows, when it is below the nominal value, to better select the width of the current lines in order to obtain the proper resistance close to the nominal value.

[0013] In glazing areas where the power density is too low, increasing the width of the current lines correspondingly reduces the width of the electrically conductive strips, resulting in an increase in their resistance R and at the same time a decrease in their area S, which are two sources of local increase in power density R⋅i ² / S. EFFECT: invention makes it possible to significantly reduce the number of cold spots even in the absence of a heating layer thickness gradient.

[0014] Multiple electrically conductive layers may be simultaneously present at different thickness levels of the laminated glazing.

[0015] According to specific embodiments:

[0016] - the electrically conductive layer is based on a metal oxide, such as indium oxide doped with tin (ITO), and/or tin oxide doped with fluorine SnO ₂ :F, and/or zinc oxide doped with aluminum (AZO), and/ or is based on a metal, such as gold Au and/or silver Ag, optionally in the form of a multilayer package, in particular containing at least one layer of silver;

[0017] - the electrically conductive layer has a thickness of 2 to 1600 nm;

[0018] - the electrically conductive layer has a thickness gradient, that is, a change in its thickness, which is not constant;

[0019] - streamlines have a width of 5 to 1000 microns;

[0020] - the distance between two adjacent current lines is greater than or equal to 8 mm, does not exceed 40 mm and is in ascending order of preference 30, 25 and 20 mm;

[0021] - the electrically conductive layer has phase separation lines consisting of ablation lines with a width of 500 to 2000 microns; in the case of three-phase current, these phase separation lines delimit three zones of different phases;

[0022] - Said rigid transparent bases are made of glass such as soda-lime, aluminosilicate, borosilicate glass, optionally chemically strengthened, thermally semi-tempered or tempered, or of a polymeric material such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET) or polyurethane (PU);

[0023] - the electrically conductive layer is located on the side facing the inside of the laminated glazing of at least one of the two rigid transparent bases from which the two outer surfaces of the laminated glazing are formed;

[0024] - the intermediate adhesive layer is selected from polyvinyl butyral (PVB), polyurethane (PU), polyethylene vinyl acetate (EVA), ionomers used alone or in a mixture of a dozen of them;

[0025] - at least one streamline (92; 93) has a locally increased width to locally increase the electrical resistance, locally reduce the area of the conductive zone and locally increase the heating power density to eliminate the formation of cold spots; this takes place, in particular, in a corner zone of a complex shape deviating from a right angle, where the heating power density is insufficient.

[0026] The subject of the invention is also a method of manufacturing the above-described laminated glazing, including the formation on the electrically conductive layer of streamlines of controlled variable width by ablation using a pulsed laser in combination with a laser spot displacement scanner, and/or by localized chemical etching of the electrically conductive layer, and /or by depositing a first coating, e.g. paint in a pattern corresponding to streamlines, depositing an electrically conductive layer as a second coating, and then removing, e.g. by dissolving, said first coating and part of the electrically conductive layer covering it. This last operation is known by the English term "lift-off" (reverse lithography).

[0027] Another object of the invention relates to the use of the above-described laminated glazing as heated glazing in an air, ground, in particular railway, water, in particular maritime, armored vehicle.

[0028] According to the first embodiment of the present application, the sides of said rigid transparent bases are numbered starting from the side designated as side 1 in contact with the outside atmosphere, and the electrically conductive layer covers the n side of the laminated glazing, where n is greater than or equal to 2, preferably equals 2 for de-icing/anti-icing glazing applications.

[0029] According to a second embodiment of the present application, the sides of said rigid transparent bases are numbered as defined above, and the electrically conductive layer covers the n side of the laminated glazing, where n is greater than or equal to 3, preferably the side of the rigid transparent base that contacts the interior of the laminated glazing. volume of the vehicle, for use as a glazing that eliminates/prevents fogging.

[0030] The invention is illustrated in the accompanying drawings, in which:

[0031] FIG. 1 shows a rigid transparent base (substrate) coated with an anti-icing heating layer provided as part of an intricately shaped laminated glazing in an aircraft cockpit; front view.

[0032] FIG. 2 is a partial schematic front view of an anti-icing heating layer, such as the layer of FIG. 1, containing streamlines according to the invention.

[0033] Referring to FIG. 1, a transparent aluminosilicate glass substrate (substrate) is coated with an electrically conductive tin-doped indium oxide (ITO) layer 2 of substantially uniform thickness, zone 1 of which has four pairwise opposite edges (3, 5), (4, 6), and while the first and second tires 7, 8 are located along two opposite edges 3,5.

[0034] The ablation lines of the electrically conductive layer 2 form streamlines 9 for conducting electrical current between the busbars 7, 8.

[0035] If these streamlines 9 are of constant width, the corner area circled in FIG. 1 is an area with a lower heating power density than the central zones of the anti-icing heating layer 2. In this corner zone, the power density is insufficient.

[0036] To correct this, the streamlines 9 have, according to the invention, a variable width, as shown in Fig.2. For example, streamline 91 has a constant width of 200 µm, streamline 92 has a constant width of 600 µm, and streamline 93 has a width varying from 200 to 600 µm. Thus, expanding the current lines 92, 93 locally increases the electrical resistance, while the area of the conductive zone is reduced, and the heating power density is locally increased in order to eliminate the appearance of cold spots even in the absence of a thickness gradient of the heating layer 2.

[0037] The following tables 1, 2 and 3 give examples of increasing the resistance (impedance) Ra between the leads (busbars) of a 200 nm thick ITO electrically conductive layer provided with 60 equidistant current paths between the current leads spaced 100 mm apart, depending on the width heating layer and current line width.

Table 1

layer resistivity 2∙10 ^-6 Ohm∙m layer width 1000 mm distance between leads 100 mm line width 100 micron number of lines 60 layer thickness 200 nm Ra without lines one Ohm Ra with lines 1.01 Ohm ∆R 0.60 %

table 2

layer resistivity 2∙10 ^-6 Ohm∙m layer width 1000 mm distance between leads 100 mm line width 600 micron number of lines 60 layer thickness 200 nm Ra without lines one Ohm Ra with lines 1.04 Ohm ∆R 3.73 %

Table 3

layer resistivity 2∙10 ^-6 Ohm∙m layer width 800 mm distance between leads 100 mm line width 600 micron number of lines 60 layer thickness 200 nm Ra without lines 1.25 Ohm Ra with lines 1.31 Ohm ∆R 4.71 %

[0038] From a comparison of Table 1 and Table 2, it follows that with a heating layer width of 1000 mm, an increase in the width of the current lines from 100 to 600 μm leads to an increase in the resistance between current leads Ra by 3.73% instead of 0.60% in the absence of current lines .

[0039] From Table 3, it can be seen that with a width of the electrically conductive layer of 800 mm, current lines 600 µm wide result in a 4.71% increase in resistance compared to no current lines.

Claims (15)

1. Multilayer glazing, consisting of a plurality of rigid transparent bases, connected to each other in pairs by means of an intermediate adhesive layer, and at least one of these transparent bases is covered with an electrically conductive layer (2), while the zone (1) of this transparent base has four pairs opposite edges (3, 5), (4, 6) and the first and second tires (7, 8) are located along two opposite edges (3,5), the electrically conductive layer (2) has streamlines (9; 91; 92; 93 ) for conducting electric current between the tires (7, 8), characterized in that the set of current lines (9; 91; 92; 93) has a variable width. 2. Laminated glazing according to claim 1, characterized in that the electrically conductive layer (2) is based on a doped metal oxide such as tin doped indium oxide (ITO) and/or fluorine doped tin oxide SnO ₂ :F, and /or zinc oxide doped with aluminum (AZO) and/or a metal such as gold Au and/or silver Ag, optionally in the form of a multilayer package, in particular containing at least one layer of silver. 3. Laminated glazing according to claim 1 or 2, characterized in that the electrically conductive layer (2) has a thickness of 2 to 1600 nm. 4. Laminated glazing according to one of the preceding claims, characterized in that the electrically conductive layer (2) has a thickness gradient. 5. Laminated glazing according to one of the previous paragraphs, characterized in that the width of the streamlines (9; 91; 92; 93) is from 5 to 1000 microns. 6. Laminated glazing according to one of the preceding claims, characterized in that the distance between two adjacent streamlines is at least 8 mm, at most 40 mm, and in increasing order of preference 30, 25 and 20 mm. 7. Laminated glazing according to one of the preceding claims, characterized in that the electrically conductive layer (2) has phase separation lines consisting of ablation lines with a width of 500 to 2000 µm. 8. Laminated glazing according to one of the preceding claims, characterized in that said rigid transparent bases are made of glass, such as soda-lime, aluminosilicate, borosilicate glass, optionally chemically strengthened, thermally semi-tempered or tempered, or of a polymeric material, such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET) or polyurethane (PU). 9. Laminated glazing according to one of the preceding claims, characterized in that the electrically conductive layer (2) is located on the side facing the interior of the laminated glazing of at least one of the two rigid transparent bases that form the two outer surfaces of the laminated glazing. 10. Laminated glazing according to one of the preceding claims, characterized in that the intermediate adhesive layer is selected from polyvinyl butyral (PVB), polyurethane (PU), polyethylene vinyl acetate (EVA), ionomers used alone or in a mixture of a plurality of them. 11. Laminated glazing according to one of the preceding claims, characterized in that the streamline (92; 93) has at least a locally increased width in order to locally increase the electrical resistance, locally reduce the area of the conductive zone and locally increase the heating power density in order to eliminate the formation cold spots. 12. A method for manufacturing multi-layer glazing according to one of the previous claims, including the formation on the electrically conductive layer (2) of streamlines (9; 91; 92; 93) of controlled variable width by ablation using a pulsed laser in combination with a scanner for shifting the laser spot, by localized chemical etching of the electrically conductive layer (2) and/or by depositing a first coating, such as paint in a pattern corresponding to the streamlines (9; 91; 92; 93), depositing the electrically conductive layer (2) as a second coating, and then removing, such as a dissolution of said first coating and part of the electrically conductive layer (2) covering it. 13. The use of laminated glazing according to one of paragraphs. 1-11 as a heated glazing in an air, land, in particular railway, water, in particular sea, armored vehicle. 14. Use according to claim 13, wherein the sides of said rigid transparent substrates are numbered starting from the side in contact with the outside atmosphere and designated as side 1, and the electrically conductive layer (2) covers the n side of the laminated glazing, where n is greater than or equal to 2 is preferably equal to 2 for de-icing/anti-icing glazing applications. 15. Use according to claim 13, wherein the sides of said rigid transparent substrates are numbered starting from the side in contact with the outside atmosphere and designated as side 1, and the electrically conductive layer (2) covers the n side of the laminated glazing, where n is greater than or equal to 3, said side is preferably oriented towards the inside of a rigid transparent base laminated glazing in contact with the interior of a vehicle for use as an anti-fogging/anti-fogging glazing.

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