LAMINATED GLAZING COMPRISING A TRANSPARENT SUBSTRATE WITH A HEATING LAYER HAVING FLOW LINES WHICH ALTOGETHER ARE OF VARIABLE WIDTH

Abstract

A laminated glazing is formed of several rigid transparent substrates adhesively bonded in pairs by an interlayer adhesive layer, at least one of these transparent substrates being coated with an electrically conductive layer, a zone of this transparent substrate exhibiting four opposite edges in pairs, a first and a second busbar being positioned along two opposite edges, the electrically conductive layer exhibiting flow lines for guiding the electric current between the busbars, the set of flow lines being of variable width.

Claims

1. A laminated glazing formed of several rigid transparent substrates adhesively bonded to one another in pairs via an interlayer adhesive layer, at least one transparent substrate of the several rigid transparent substrates being coated with an electrically conductive layer, a zone of the transparent substrate exhibiting four opposite edges in pairs, a first and a second busbar being positioned along two opposite edges, the electrically conductive layer exhibiting a set of flow lines for guiding an electric current between the first and second busbars, wherein the set of the flow lines is of variable width.

2. The laminated glazing as claimed in claim 1, wherein the electrically conductive layer is based on doped metal oxide, optionally in the form of a multilayer stack.

3. The laminated glazing as claimed in claim 1, wherein the electrically conductive layer has a thickness of between 2 and 1600 nm.

4. The laminated glazing as claimed in claim 1, wherein the electrically conductive layer exhibits a thickness gradient.

5. The laminated glazing as claimed in claim 1, wherein the flow lines have a width of between 5 and 1000 μm.

6. The laminated glazing as claimed in claim 1, wherein a distance between two neighboring flow lines is at least equal to 8 and at most to 40 mm.

7. The laminated glazing as claimed in claim 1, wherein the electrically conductive layer exhibits phase separation lines consisting of ablation lines with a width of between 500 and 2000 μm.

8. The laminated glazing as claimed in claim 1, wherein said rigid transparent substrates are made of glass, which is optionally chemically reinforced, heat tempered or semi-tempered, or of polymer material.

9. The laminated glazing as claimed in claim 1, wherein the electrically conductive layer is on a face oriented toward an inside of the laminated glazing of at least one of two rigid transparent substrates constituting two exterior surfaces of the laminated glazing.

10. The laminated glazing as claimed in claim 1, wherein the interlayer adhesive layer is chosen from polyvinyl butyral (PVB), polyurethane (PU), poly(ethylene/vinyl acetate) (EVA), ionomer, alone or as a mixture of several of them.

11. The laminated glazing as claimed in claim 1, wherein one flow line at least has a locally increased width, in order to locally increase an electrical resistance, locally decrease a surface area of the conductive zone and locally increase a heating power density, so as to eliminate a cold point.

12. A process for the manufacture of a laminated glazing as claimed in claim 1, comprising forming, on an electrically conductive layer, flow lines of controlled variable width by ablation by a pulsed laser combined with a scanner in order to move a laser spot, by localized chemical stripping of the electrically conductive layer and/or by deposition of a first coating according to a pattern corresponding to the flow lines, depositing a second coating of the electrically conductive layer, then eliminating said first coating and a fraction of the electrically conductive layer covering it.

13. A method comprising manufacturing a heated glazing for an aerial, ground or water vehicle which is armored with the laminated glazing as claimed in claim 1.

14. The method as claimed in claim 13, in which the faces of said rigid transparent substrates are numbered starting from that in contact with an external atmosphere, defined as face 1, and the electrically conductive layer coats a face n of the laminated glazing, with n greater than or equal to 2, for an application as deicing/anti-icing glazing.

15. The method as claimed in claim 13, in which the faces of said rigid transparent substrates are numbered starting from that in contact with the external atmosphere, defined as face 1, and the electrically conductive layer coats a face n of the laminated glazing, with n greater than or equal to 3.

16. The laminated glazing as claimed in claim 2, wherein the doped metal oxide is indium oxide doped with tin (ITO) and/or tin oxide doped with fluorine SnO.sub.2:F and/or zinc oxide doped with aluminum (AZO), and the metal is gold Au and/or silver Ag.

17. The laminated glazing as claimed in claim 1, wherein the multilayer stack comprises at least one silver layer.

18. The laminated glazing as claimed in claim 6, wherein the distance between two neighboring flow lines is 20 mm.

19. The laminated glazing as claimed in claim 8, wherein said glass is a soda-lime, aluminosilicate or borosilicate glass, and the polymer material is poly(methyl methacrylate) (PMMA), polycarbonate (PC), poly(ethylene terephthalate) (PET) or polyurethane (PU).

20. The method as claimed in claim 15, wherein the electrically conductive layer coats the face oriented toward the inside of the laminated glazing of the rigid transparent substrate in contact with the interior volume of the vehicle, as demisting/antimisting glazing.

Description

THE APPENDED DRAWINGS ILLUSTRATE THE INVENTION

[0033] FIG. 1 represents a rigid transparent substrate coated with an anti-icing heating layer, and intended to form part of an aircraft cockpit laminated glazing of complex shape; front view.

[0034] FIG. 2 is a partial diagrammatic front view of an anti-icing heating layer such as that of FIG. 1 comprising flow lines in accordance with the invention.

[0035] With reference to FIG. 1, a transparent substrate made of alum inosilicate glass is coated with an electrically conductive layer 2 made of indium oxide doped with tin (ITO) with a substantially uniform thickness, a zone 1 of which exhibits four opposite edges in pairs (3, 5), (4, 6), a first and a second busbar 7, 8 being positioned along two opposite edges 3, 5.

[0036] Ablation lines of the electrically conductive layer 2 constitute flow lines 9 to guide the electric current between the busbars 7, 8.

[0037] If these flow lines 9 are of constant width, the rounded corner zone in FIG. 1 is a zone with a lower heating power density than that of the central zones of the anti-icing heating layer 2. In this corner zone, the power density is insufficient.

[0038] In order to remedy this, the flow lines 9 are of variable width according to the invention, as represented in FIG. 2. For example, the flow line 91 is of constant width 200 μm, the flow line 92 is of constant width 600 μm and the flow line 93 has a width varying from 200 to 600 μm. By thus widening the flow lines 92, 93, the electrical resistance is locally increased, the surface area of the conductive zone is reduced and the heating power density is locally increased, so as to eliminate the cold point, even in the absence of a thickness gradient of the heating layer 2.

[0039] The following tables 1, 2 and 3 give examples of gain in resistance between leads (busbars) (total resistance) Ra of an electrically conductive layer made of ITO with a thickness of 200 nm, provided with 60 equidistant flow lines, between leads 100 mm apart, as a function of the width of the heating layer and of the width of the flow lines.

TABLE-US-00001 TABLE 1 Layer resistivity 2.10.sup.−6 ohm .Math. m Layer width 1000 mm Distance between leads 100 mm Width of lines 100 μm Number of lines 60 Layer thickness 200 nm Ra without lines 1 ohm Ra with lines 1.01 ohm Delta R 0.60 %

TABLE-US-00002 TABLE 2 Layer resistivity 2.10.sup.−6 ohm .Math. m Layer width 1000 mm Distance between leads 100 mm Width of lines 600 μm Number of lines 60 Layer thickness 200 nm Ra without lines 1 ohm Ra with lines 1.04 ohm Delta R 3.73 %

TABLE-US-00003 TABLE 3 Layer resistivity 2.10.sup.−6 ohm .Math. m Layer width 800 mm Distance between leads 100 mm Width of lines 600 μm Number of lines 60 Layer thickness 200 nm Ra without lines 1.25 ohm Ra with lines 1.31 ohm Delta R 4.71 %

[0040] On comparing table 1 and table 2, for a heating layer width of 1000 mm, widening the flow lines from 100 to 600 μm increases the resistance between leads Ra by 3.73% instead of 0.60%, compared with an absence of flow lines.

[0041] In table 3, it is seen that, for an electrically conductive layer width of 800 mm, flow lines with a width of 600 μm cause the resistance to increase by 4.71%, still compared with an absence of flow lines.