GLAZING, METHOD OF MANUFACTURING SAID GLAZING AND USE OF SAID GLAZING

Abstract

A glazing comprises first and second busbars for connection to an electrical supply; a third busbar between the first and second busbars; plural conductors electrically connected to the first busbar; wherein a first group of the conductors extends from the first busbar to the third busbar to form a first resistor; a second group of the conductors extends from a side of the third busbar facing the second busbar and is electrically connected to the second busbar to form a second resistor; fewer conductors extend from the side of the third busbar facing the second busbar than extend from a side of the third busbar facing the first busbar; at least one gap on one side of the third busbar opposite a conductor on the other side and an information acquisition area between the third busbar and the second busbar, the at least one gap being outside the information acquisition area.

Claims

1. A glazing comprising: first and second busbars for connection to an electrical supply; a third busbar positioned between the first and second busbars; a plurality of conductors electrically connected to the first busbar; wherein: the plurality of conductors includes a first group of conductors extending from the first busbar to the third busbar to form a first resistor; the plurality of conductors includes a second group of conductors extending from a side of the third busbar facing the second busbar and electrically connected to the second busbar to form a second resistor; wherein fewer conductors extend from the side of the third busbar facing the second busbar than extend from a side of the third busbar facing the first busbar; at least one gap on one side of the third busbar opposite a conductor on the other side; an information acquisition area arranged between the third busbar and the second busbar; wherein the at least one gap is positioned outside the information acquisition area.

2. A glazing according to claim 1, comprising a fourth busbar positioned between the third busbar and the second busbar wherein: the second group of conductors extends to the fourth busbar to form the second resistor; a third group of conductors extends from the fourth busbar to the second busbar to form a third resistor.

3. A glazing according to claim 2, wherein more conductors extend from a side of the fourth busbar facing the second busbar than extend from a side of the fourth busbar facing the third busbar.

4. A glazing according to claim 1, wherein the information acquisition area is arranged between the third busbar and the fourth busbar.

5. A glazing according to claim 1, wherein fewer conductors extend from a side of the third busbar facing the second busbar than extend from a side of the third busbar facing the first busbar outside the information acquisition area.

6. A glazing according to claim 1, wherein the conductors are heating wires.

7. A glazing according to claim 1, wherein a group of conductors extends from the first busbar to: the second busbar to form a parallel resistor, or a split busbar to form a split busbar parallel resistor and a distance between the first busbar and the split busbar selected to be different from a distance between the first busbar and the second busbar.

8. A glazing according to claim 1, wherein a power density in a region of the second resistor is greater than a power density of the first resistor or the parallel resistor or the split busbar parallel resistor, or any combination thereof.

9. A glazing according to claim 1, comprising outer and inner plies of glazing material and a ply of interlayer material therebetween to form a laminated glass wherein first and second resistors are between the ply of interlayer material and the inner ply of glazing material.

10. A method of manufacturing a glazing, comprising: providing first and second busbars for connecting to an electrical supply; positioning a third busbar between the first and second busbars; electrically connecting a plurality of conductors to the first busbar; extending a first group of the plurality of conductors from the first busbar to the third busbar to form a first resistor; extending a second group of the plurality of conductors from a side of the third busbar facing the second busbar and electrically connecting said second group of conductors to the second busbar to form a second resistor; wherein fewer conductors extend from the side of the third busbar facing the second busbar than extend from a side of the third busbar facing the first busbar; removing at least a part of at least one conductor on one side of the third busbar to form at least one gap on one side of the third busbar opposite a conductor on the other side; arranging an information acquisition area between the third busbar and the second busbar; and positioning the at least one gap outside the information acquisition area.

11. Use of a glazing according to claim 1, in a motor vehicle as a windshield, a rear window, side window or roof window, or as a window in an aircraft, in a train or in a building.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a glazing according to the invention having three busbars.

[0034] FIG. 2 is a glazing according to the invention having a split busbar.

[0035] FIG. 3 is a glazing according to the invention having four busbars and one gap.

[0036] FIG. 4 is a glazing according to the invention having two gaps.

[0037] FIG. 5 is a glazing according to the invention having three gaps.

[0038] FIG. 6 is a glazing according to the invention having four gaps.

[0039] FIG. 7 is a glazing according to the invention having four gaps and a split busbar.

[0040] FIG. 8 is an equivalent circuit of the glazing of FIG. 7.

[0041] FIG. 9 is a cross-section of a laminated glass according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0042] The following is a description with reference to the drawings, wherein reference numerals have the same meaning throughout.

[0043] FIG. 1 is a plan view of a glazing 10 according to the invention having conductors 5 for electrically heating the glazing. The glazing 10 is generally trapezoidal in shape, suitable for a vehicle windshield.

[0044] First busbar 1 and second busbar 2 are provided, shown adjacent upper and lower edges of the glazing 1 for connection to an external electrical supply (not shown). A third busbar 3 is positioned between first and second busbars, shown as parallel to and closer to first busbar 1. Conductors 5 are electrically connected to the first busbar 1.

[0045] A first group of conductors extends from the first busbar 1 to the third busbar 3 to form a first resistor R1. A second group of conductors extends from a side of the third busbar 3 facing the second busbar 2 and is electrically connected to the second busbar 2 to form a second resistor R2. First resistor 1 and second resistor 2 are electrically in series forming a series combination so the same current flows through resistor 1 and resistor 2.

[0046] Fewer conductors extend from a side of the third busbar 3 facing the second busbar 2 than extend from a side of the third busbar 3 facing the first busbar 1. One of the conductors of the second resistor R2 has been removed to form a gap 6.

[0047] A parallel resistor R is arranged to one side of first and second resistors R1, R2 and is electrically in parallel with them so that the same voltage is applied to parallel resistor R and the series combination of first and second resistors R1, R2. Parallel resistor R is connected to first and second busbars 1, 2, in the same way as the series combination of first and second resistors R1, R2.

[0048] FIG. 2 is a plan view of another glazing 10 according to the invention. It differs from FIG. 1 in that a split busbar 8 is provided so that a split busbar parallel resistor R8 can have a different distance between busbars than the series combination of first and second resistors R1, R2. Split busbar parallel resistor R8 can optionally be electrically connected to second busbar 2, so that it is electrically in parallel with the series combination of first and second resistors R1, R2.

[0049] FIG. 3 is a plan view of a glazing 10 according to the invention. It differs from FIG. 1 by having a fourth busbar 4 positioned between the third busbar 3 and the second busbar 2. The second group of conductors extends to the fourth busbar 4 to form the second resistor R2. A third group of conductors extends from the fourth busbar to the second busbar to form a third resistor R3. An information acquisition area 7 is positioned in second resistor R2. A gap 6 is positioned in second resistor R2 outside the information acquisition area 7.

[0050] FIG. 4 is a plan view of a glazing 10 according to the invention. It differs from FIG. 3 by having two gaps 6 in second resistor R2 outside the information acquisition area 7, on one side thereof. The two gaps 6 are separated by one conductor 5.

[0051] FIG. 5 is a plan view of a glazing 10 according to the invention. It differs from FIG. 4 by having three gaps 6 in second resistor R2 outside the information acquisition area 7, one on one side thereof and two on the other side, separated by two conductors 5.

[0052] FIG. 6 is a plan view of a glazing 10 according to the invention. It differs from FIG. 5 by having four gaps 6 in second resistor R2 outside the information acquisition area 7, two on one side thereof, separated by one conductor 5, and two on the other side, separated by two conductors 5. Only a small number of conductors 5 are shown for clarity. Not all conductors 5 are shown. Combinations of number of gaps 6 and number of conductors 5 between the gaps 6 are not limited. Notwithstanding, removing too many conductors 5 such that a wide gap 6 is formed resulting in an unheated cold spot outside the information acquisition area 7 would be undesirable if, for example, wipers are unable to clear a windshield.

[0053] FIG. 7 is a plan view of a glazing 10 according to the invention. It differs from FIG. 6 by having a split busbar 8 and split busbar parallel resistor R8 like FIG. 2.

[0054] FIG. 8 is a circuit diagram of a glazing 10 according to the invention corresponding to FIG. 7. An optional switch is for an optional electrical connection (not shown in FIG. 7) so that split busbar parallel resistor R8 can be electrically in parallel with the series combination of first and second resistors R1, R2.

[0055] FIG. 9 is a cross-section of a glazing 10 according to the invention corresponding to FIG. 3 to FIG. 7. Outer ply of glazing material 11 and inner ply of glazing material 12 have a ply of interlayer material 13 between.

EXAMPLES

[0056] The following is a description of non-limiting examples of the present invention.

[0057] Table 1 shows results of a first simulation of a glazing generally as FIG. 1 to FIG. 9 of nominal power density 600 W/m.sup.2. Power density in a required region can be increased to 1,228 W/m.sup.2 by having up to twelve fewer conductors in an adjacent region of width 30 mm outside the required region but still in the second resistor R2. Number of conductors inside the required region is 23, so total number of conductors in the first resistor R1 is 35. Alternatively, removing two conductors, one each to the left and right of the required region, increases power density to 665 W/m.sup.2.

[0058] Table 1 discloses increased power density for a comparative example having no conductors removed (gaps) and four examples having between two and twelve fewer conductors in the second resistor R2 than in the first resistor R1.

TABLE-US-00001 TABLE 1 Comparative Example Example Example Example example 1 2 3 4 Number of conductors 0 2 4 8 12 fewer (gaps) outside information acquisition area Conductors remaining 12 10 8 4 0 outside information acquisition area Power density above/below 600 595 590 578 563 information acquisition area Power density in 600 665 741 939 1,228 information acquisition area

[0059] Table 2 shows results of a second simulation of a glazing generally as FIG. 3 to FIG. 6 having nominal power density 600 W/m.sup.2. Power density can be increased in a required region to 742 W/m.sup.2 by having four fewer conductors in an adjacent region of width 10 mm outside the required region but still in the second resistor R2. Number of conductors inside the required region is 32, so total number of conductors in the first resistor R1, and in the third resistor R3, is 36.

[0060] Table 2 discloses increased power density for the example having four conductors removed (gaps) in an information acquisition area and having a distance from the second resistor to the first busbar different from a distance from the second resistor to the second busbar.

TABLE-US-00002 TABLE 2 Parallel First Second Third Series resistor resistor resistor resistor combination R R1 R2 R3 R1 + R2 + R3 Distance between busbars (mm) 886 56 59 771 886 Width (mm) 522 93 93 93 93 Number of conductors fewer 0 0 4 0 N/A Conductors remaining 201 36 32 36 N/A Resistance (ohms) 0.548 0.194 0.229 2.675 3.098 Power density (W/m.sup.2) 600 591 742 591 N/A

[0061] Table 2 shows that power density above/below the second resistor R2 is 591 W/m.sup.2. To achieve the nominal power density across the glazing the split busbar 8 of FIG. 2 or FIG. 7 is required, so that the distance between busbars for the split busbar parallel resistor and the series combination R1, R2, R3 can be different.

[0062] Table 3 discloses results of a third simulation of a glazing generally as FIG. 7 having nominal power density 600 W/m.sup.2. Power density can be increased in a required region to 753 W/m.sup.2 by having four fewer conductors in an adjacent region of width 10 mm outside the required region but still in the second resistor R2. Number of conductors inside the required region is 32, so total number of conductors in the first resistor R1, and in the third resistor R3, is 36. Differences compared with Table 2 are underlined.

TABLE-US-00003 TABLE 3 Parallel First Second Third Series resistor resistor resistor resistor combination R R1 R2 R3 R1 + R2 + R3 Distance between busbars (mm) 886 56 59 764  879 Width (mm) 522 93 93 93  93 Number of conductors fewer 0  0  4  0 N/A Conductors remaining 201 36 32 36 N/A Resistance (ohms) 0.548    0.194    0.229    2.651     3.074 Power density (W/m.sup.2) 600 600  753  600  N/A

[0063] Difference in distance between busbars is 886−879=7 mm. Reducing the distance between busbars in the series combination R1, R2, R3 compared with the distance between busbars in the parallel resistor restores nominal power density to first and third resistors to compensate for the increased resistance of the second resistor due to the fewer conductors therein.

[0064] In all simulations the applied voltage is 12.33 volts. Conductor spacing is 2.6 mm. Conductors are simulated as wires of resistivity 116 ohms/m and having increased path length due to crimped shape of 107%.

[0065] The present invention may have any number of required regions having fewer conductors extending from the side of an additional busbar facing the second busbar than extend from a side of the additional busbar facing the first busbar. Two or more regions may be spaced across the width of the glazing, for example left and right for stereo cameras. Two or more regions may be spaced along the height of the glazing, for example a series combination of first, second, third, fourth and fifth resistors having third, fourth, fifth and sixth busbars between them. Second and fourth resistors have fewer conductors, providing higher power density in two regions, for example at top and bottom of the glazing.

[0066] First and second groups of conductors may be partly formed by a plurality of continuous wires which are partly overlapped by at least first, second and third busbars.

[0067] The method of manufacturing may comprise a step of embedding a plurality of conductors in the form of continuous wires in a ply of interlayer material. Preferably, sections of selected continuous wires between the third busbar and the second busbar or the fourth busbar are cut and removed.

[0068] First, second and third examples according to the invention and one comparative example were made. The examples were as FIG. 5 but had two, four and five wires removed in each respective second group of conductors. Gaps due to wire removal were positioned outside the information acquisition area. Gaps were left and right, two left and two right, two left and three right, respectively. The comparative example had no wires removed.

[0069] In a standard defrost test known in the art, time required for the information acquisition area to reach the temperature 0° was measured for each example relative to the time required for the comparative example. The first example was 30 seconds faster, the second example was 60 seconds faster and the third example was 80 seconds faster.

REFERENCE NUMERALS IN THE DRAWINGS

[0070] 1, 2, 3, 4: First, second, third, fourth busbar

[0071] 5: Conductors

[0072] 6: Gap

[0073] 7: Information acquisition area

[0074] 8: Split busbar

[0075] 10: Glazing

[0076] 11: Outer ply of glazing material

[0077] 12: Inner ply of glazing material

[0078] 13: Ply of interlayer material

[0079] R: Parallel resistor

[0080] R1, R2, R3: First, second, third resistor

[0081] R8: Split busbar parallel resistor