LAMINATED GLAZING COMPRISING A TRANSPARENT SUBSTRATE WITH A HEATING LAYER HAVING ABLATION LINES EACH CLOSING ON ITSELF

Abstract

A laminated glazing has a plurality of rigid transparent substrates that are bonded to one another pairwise via an intercalary adhesive layer, at least one of these transparent substrates being coated with an electrically conductive layer that is substantially uniform in nature and thickness, a zone of which has four edges opposing one another in pairs, first and second busbars being arranged along two opposite edges, ablation lines of the electrically conductive layer closing in on themselves while forming non-conductive strips, each occupying a major portion of the distance between the busbars, the shape of the non-conductive strips being capable of providing a temperature of heating by the electrically conductive layer that is virtually constant over the entire area of the zone.

Claims

1. A laminated glazing consisting of a plurality of rigid transparent substrates that are bonded to one another pairwise via an intercalary adhesive layer, at least one of the plurality of rigid transparent substrates being coated with an electrically conductive layer that is substantially uniform in nature and thickness, a zone of said least one rigid transparent substrate having four edges opposing one another in pairs, first and second busbars being arranged along two opposite edges, wherein ablation lines of the electrically conductive layer close in on themselves while forming non-conductive strips, each occupying a major portion of a distance between the first and second busbars, a shape of the non-conductive strips being capable of providing a temperature of heating by the electrically conductive layer that is virtually constant over the entire area of the zone.

2. The laminated glazing as claimed in claim 1, wherein the distance between the first and second busbars varies along the opposite edges, and wherein a width of the conductive strips increases with the distance between the first and second busbars.

3. The laminated glazing as claimed in claim 1, wherein the first busbar is longer than the second busbar, and wherein the width of each conductive strip increases from the first busbar to the second.

4. The laminated glazing as claimed in claim 1, wherein the electrically conductive layer is based on doped metal oxide, or on a silver multilayer stack.

5. The laminated glazing as claimed in claim 1, wherein the surface conductivity or sheet resistance of the conductive layer is between 0.5 and 100 /.

6. The laminated glazing as claimed in claim 1, wherein the width of the ablation lines ranges from 5 to 200 m.

7. The laminated glazing as claimed in claim 1, wherein the width of the conductive strips is at least equal to 50 m, and at most equal to 5 mm.

8. The laminated glazing as claimed in claim 1, wherein a pitch of the pattern of the conductive strips and of the non-conductive strips is at least equal to 0.5 mm, and at most equal to 10 4 mm.

9. The laminated glazing as claimed in claim 1, wherein the transparent substrate that is coated with the electrically conductive layer is made of glass, or made of polymer material.

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

11. The laminated glazing as claimed in claim 1, wherein the intercalary adhesive layer is chosen from polyvinyl butyral, polyurethane and ethylene/vinyl acetate, alone or in a blend of a number thereof.

12. A method comprising utilizing a laminated glazing as claimed in claim 1 as a defrosting/anti-frost glazing, wherein the transparent substrate coated with the electrically conductive layer makes contact with the outside atmosphere.

13. A method comprising utilizing a laminated glazing as claimed in claim 1 as a defogging/anti-fog glazing, wherein the transparent substrate coated with the electrically conductive layer makes contact with the interior space of a vehicle or of a building.

14. The laminated glazing as claimed in claim 4, wherein the electrically conductive layer is a layer of tin-doped indium oxide (ITO) or SnO.sub.2:F.

15. The laminated glazing as claimed in claim 7, wherein the width of the conductive strips is at least equal to 200 m, and at most equal to 3 mm.

16. The laminated glazing as claimed in claim 8, wherein a pitch of the pattern of the conductive strips and of the non-conductive strips is at least equal to 1 mm, and at most equal to 4 mm.

17. The laminated glazing as claimed in claim 9, wherein the glass is a soda-lime, aluminosilicate or borosilicate glass, and the polymer material is a poly(methyl methacrylate) (PMMA), polycarbonate (PC) or polyurethane (PU).

Description

[0039] The invention will be better understood in the light of the following description of the appended FIGS. 1 and 2, which are schematic representations of two main embodiments of a transparent substrate that is characteristic of the laminated glazing of the invention.

[0040] With reference to FIGS. 1 and 2, a transparent substrate made of aluminosilicate glass is coated with an electrically conductive layer (2) made of tin-doped indium oxide (ITO) that is substantially uniform in thickness, a zone (1) of which has four edges opposing one another in pairs (3, 5), (4, 6), first and second busbars (7, 8) being arranged along two opposite edges (3, 5).

[0041] Ablation lines (9) of the electrically conductive layer (2) close in on themselves while forming non-conductive strips (11), each occupying a major portion of the distance between the busbars (7, 8). The area that is complementary to the non-conductive strips (11) in the zone (1) defines conductive strips (10).

Exemplary Embodiment Shown in FIG. 1:

[0042] Specific power: Ps=7000 W/m.sup.2

[0043] Surface resistivity: R squared=0.9 /

[0044] Supply voltage: U=40 V

[0045] Width: L=0.4 m

[0046] Maximum height H1=0.4 m

[0047] Minimum height H2=0.2 m

[0048] An abscissa x that goes from 0 at the maximum height H1 to 0.4 m at the minimum height H2 is defined. The height H at an abscissa x is

H(x)=H1+x/L.Math.(H2H1)

[0049] The width or pitch of the pattern is defined as the width of one conductive strip (10) and one non-conductive strip (11) that are adjacent to one another; the value of it here is e0=600 m, i.e. 667 patterns.

[0050] The width of the conductive strip (10) depends on the position:

[00002]$e=e.Math.0.Math.\frac{\mathrm{Rsquared}.Math.\mathrm{Ps}.Math.H^2\left(x\right)}{U^2}$

[0051] This gives the following numerical application: [0052] The conductive width on the side of the shortest distance between busbars (H2) is e1=95 m [0053] The conductive width on the side of the longest distance between busbars (H1) is e2=378 m

Exemplary Embodiment Shown in FIG. 2:

[0054] busbar with L1=1 m and L2=1.5 m

[0055] distance between busbars H=1 m

[0056] specific power Ps=1000 W/m.sup.2 at U=100 V

[0057] layer with R squared=5 /

[0058] n=31 conductive strips:

[0059] The width of the pattern as defined above is dependent on the position h between the two busbars x0(h)=(L1+h/H(L2L1))/n

[0060] The center of each conductive strip defines a straight line segment that forms an angle relative to the normal to the busbars.

[0061] The value of the width of the conductive strip is:

[00003]$x=\frac{R.Math.s.Math.q.Math.u.Math.a.Math.r.Math.e.Math.d}{x_0.Math..Math.{\cos }^2.Math..Math.}.Math.{\left(\frac{\left(L.Math.1+L.Math.2\right).Math.H}{2.Math.U}\right)}^2.Math.\frac{P.Math.s}{n^2}$

[0062] In this specific case, the width of the central conductive strip is 2.52 mm on the side of the short busbar (8) and 1.68 mm on the side of the long busbar (7).

[0063] The invention is thus particularly advantageous for vehicle heated glazing for which the electrical power supply is set, since it allows a desired specific power of heating to be established uniformly over the entire heating surface.