LAMINATED GLASS, ELECTRICAL ISOLATION MEASUREMENT SYSTEM HAVING THE SAME, METHOD OF MANUFACTURING THE SAME, AND USE OF THE SAME

Abstract

The present invention concerns a laminated glass, comprising first and second glass sheets and a ply of interlayer material therebetween; a heating element arranged on a surface of the second glass sheet adjacent the ply of interlayer material; a circumference of the heating element spaced from an edge of the second glass sheet forming a circumferential region between the circumference and the edge of the second glass sheet where conductive material of the heating element has been at least partly removed; a conductive ring configured in the circumferential region spaced from the circumference and spaced from the edge of the second glass sheet and electrically isolated from the heating element wherein conductive materials of the heating element and the conductive ring are different.

Claims

1.-15. (canceled)

16. A laminated glass, comprising: first and second glass sheets and a ply of interlayer material therebetween; a heating element arranged on a surface of the second glass sheet adjacent the ply of interlayer material; a circumference of the heating element spaced from an edge of the second glass sheet forming a circumferential region between the circumference and the edge of the second glass sheet where conductive material of the heating element has been at least partly removed; and a conductive ring configured in the circumferential region spaced from the circumference and spaced from the edge of the second glass sheet and electrically isolated from the heating element wherein conductive materials of the heating element and the conductive ring are different.

17. The laminated glass according to claim 16, wherein the conductive ring comprises first and second ends and a gap therebetween.

18. The laminated glass according to claim 17, further comprising first and second connection points at first and second ends of the conductive ring.

19. The laminated glass according to claim 16, further comprising first and second busbars to supply electrical power to the heating element.

20. The laminated glass according to claim 19, wherein first and second busbars are arranged on the circumference of the heating element.

21. The laminated glass according to claim 19, further comprising first and second extensions electrically connected to first and second busbars respectively and further comprising first and second terminals respectively arranged between the circumference and the conductive ring.

22. The laminated glass according to claim 21, further comprising a junction box arranged to cover first and second terminals.

23. The laminated glass according to claim 16, wherein the heating element is a conductive coating comprising a transparent conductive oxide or an array of wires comprising tungsten or copper.

24. The laminated glass according to claim 16, wherein the conductive ring comprises copper and is shaped as wire, strip or braid embedded in the ply of interlayer material or wherein the conductive ring is printed in the circumferential region using a conductive ink comprising silver powder, silver spheres, graphite powder, graphite rods, carbon nanotubes or glass flakes having a conductive coating, or sprayed particles.

25. The laminated glass according to claim 16, wherein the conductive ring is bonded to the circumferential region by a conductive adhesive comprising silver powder, silver spheres, graphite powder, graphite rods, carbon nanotubes or glass flakes having a conductive coating.

26. An electrical isolation measurement system comprising a laminated glass according to claim 16 and an electronic device electrically connected via cables to the heating element and to the conductive ring to measure resistance or leakage current.

27. A method for manufacturing a laminated glass, comprising: bonding first and second glass sheets with a ply of interlayer material therebetween; arranging a heating element at a surface of the second glass sheet adjacent the ply of interlayer material; spacing a circumference of the heating element from an edge of the second glass sheet by forming a circumferential region between the circumference and the edge of the second glass sheet where conductive material of the heating element has been at least partly removed; and configuring a conductive ring in the circumferential region spaced from the circumference and spaced from the edge of the second glass sheet and electrically isolated from the heating element wherein conductive materials of the heating element and the conductive ring are different.

28. The method for manufacturing a laminated glass according to claim 27, wherein the conductive ring is printed by silk-screen printing or inkjet printing or by spraying particles, or is a copper strip or a wire braid, embedded in the ply of interlayer material.

29. The method for manufacturing a laminated glass according to claim 27, further comprising a step of measuring electrical isolation between the heating element and the conductive ring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is an embodiment of the invention having a conductive ring without a gap.

[0033] FIG. 2 is the embodiment of FIG. 1 in cross-section.

[0034] FIG. 3 is an embodiment of the invention having busbars, extensions and a gap.

[0035] FIG. 4 is the embodiment of FIG. 3 in cross-section.

[0036] FIG. 5 is an embodiment of the invention having wires as a heating element.

[0037] FIG. 6 is the embodiment of FIG. 5 in cross-section.

[0038] FIG. 7 is an embodiment of the invention having a coating as heating element.

[0039] FIG. 8 is the embodiment of FIG. 7 in cross-section.

[0040] FIG. 9 is an embodiment of an electrical isolation measurement system.

[0041] FIG. 10 is another embodiment of an electrical isolation measurement system.

DETAILED DESCRIPTION OF THE INVENTION

[0042] FIG. 1 discloses a laminated glass (10) according to the invention comprising a first glass sheet (1) and a second glass sheet (2) bonded together by a ply of interlayer material (3).

[0043] A surface of the first glass sheet (1) not facing the ply of interlayer material (3) is surface 1 (S1). A surface of the first glass sheet (1) facing the ply of interlayer material (3) is surface 2 (S2). A surface of the second glass sheet (2) facing the ply of interlayer material (3) is surface 3 (S3). A surface of the second glass sheet (2) not facing the ply of interlayer material (3) is surface 4 (S4).

[0044] For example, the laminated glass (10) is a window wherein the first glass sheet (1) is an outer glass sheet and the second glass sheet (2) is an inner glass sheet and the surfaces (S1, S2, S3, S4) are numbered in sequence from the outside.

[0045] A heating element (4) is disposed on the ply of interlayer material (3) or on the second glass sheet (2). The heating element (4) may comprise a transparent conductive coating, for example a transparent conductive oxide such as tin oxide or fluorine-doped tin oxide deposited on the second glass sheet (2) during the glass manufacturing.

[0046] A circumference (5) of the heating element (4) is spaced from the edge of the second glass sheet (2) by a circumferential region (6) between the circumference (5) and the edge of the second glass sheet (2). Conductive material of the heating element (4) has been at least partly removed in the circumferential region. Advantageously, the conductive material is completely removed.

[0047] Removal of conductive material in the form of a coating may be by laser deletion, mechanical abrasion or other methods known in the art. If the coating is applied by sputtering, removal may include masking the second glass sheet (2) during sputtering so that little or no coating is deposited in the circumferential region (6).

[0048] A conductive ring (7) is configured in the circumferential region (6) spaced from the circumference (5) and spaced from the edge of the second glass sheet (2) and electrically isolated from the heating element (4). Conductive materials of the heating element (4) and the conductive ring (7) are different. The conductive ring (7) may by formed by screen printing a conductive ink comprising silver powder, silver spheres, graphite powder, graphite rods, carbon nanotubes or glass flakes having a conductive coating. Alternatively, the conductive ring (7) comprises copper and is shaped as wire, strip or braid embedded in the ply of interlayer material. Optionally, the conductive ring (7) is bonded to the circumferential region (6) by a conductive adhesive comprising silver powder, silver spheres, graphite powder, graphite rods, carbon nanotubes or glass flakes having a conductive coating.

[0049] FIG. 2 discloses the embodiment of FIG. 1 in cross-section on the line A-A. Thickness of the heating element (4) and the conductive ring (7) are exaggerated for clarity. In practice, thickness of the heating element (4) is typically 0.1 to 1 μm, and thickness of the conductive ring (7) is 1 to 100 μm.

[0050] FIG. 3 discloses a laminated glass (10) according to the invention like the embodiment of FIG. 1 but further comprising a gap (8) between first and second ends of the conductive ring (7); first and second connection points (9a, 9b) at first and second ends of the conductive ring (7); first and second extensions (13, 14) electrically connected to first and second busbars (11, 12) respectively, electrically connected to first and second terminals (15, 16) respectively; and a junction box (18) positioned over first and second terminals (15, 16).

[0051] FIG. 4 discloses the embodiment of FIG. 3 in cross-section on the line A-A through the second terminal (16). A portion of the second extension (14) passes through hole (17) in the second glass sheet (2) and connects with the second terminal (16) on a surface (S4) of the second glass sheet (2).

[0052] A junction box (18) is bonded to the second glass sheet (2) to electrically insulate first and second terminals (15, 16) and terminate a cable (not shown) from an external power supply. The junction box (18) may also cover a thermostat, for example an automatic reset bimetallic disc thermostat, in series with the second terminal (16) to interrupt current from the external power supply in case of excessive temperature of the second glass sheet (2).

[0053] FIG. 5 discloses a laminated glass (10) according to the invention like the embodiment of FIG. 1 wherein the heating element (4) is an array of heating wires.

[0054] FIG. 6 discloses the embodiment of FIG. 5 in cross-section on the line A-A through the gap (8). The heating wires are optionally mounted on another ply of interlayer material to form the heating element (4).

[0055] FIG. 7 discloses a laminated glass (10) according to the invention like the embodiment of FIG. 1 wherein first and second glass sheets (1, 2) are shaped to be suitable for a window of a motor vehicle, for example a trapezoidal windshield.

[0056] FIG. 8 discloses the embodiment of FIG. 7 in cross-section on the line A-A through the first extension (13). The ply of interlayer material (3) may comprise first and second plies of interlayer material (31, 32), which may be different from each other and may be a polymer, such as polyvinyl butyral (PVB) of thickness 0.76 mm, or partly opaque, such as lace or carbon fibre sheet, or a printed layer or image, for example on a surface (S2) of the first glass sheet (1). First and second glass sheets (1, 2) may be soda-lime glass.

[0057] FIG. 9 discloses an electrical isolation measurement system (20) comprising a laminated glass (10) like FIG. 1 and an electronic device (21) electrically connected via cables (22) to the heating element (4) and to the conductive ring (7) to measure resistance or leakage current.

[0058] FIG. 10 discloses an electrical isolation measurement system (20) comprising a laminated glass (10) like FIG. 5 and an electronic device (21) electrically connected via cables (22) to the heating element (4) and to the conductive ring (7) via second terminal (16) and second connection point (9b) respectively, to measure resistance or current.

Examples and Comparative Example

[0059] The invention may be used as an electrical heater for a building, for example, mounted on a wall. The invention may also be used for heated windows of vehicles for land, sea and air, for example as a windshield of a motor vehicle.

[0060] A comparative example is the transparency of U.S. Pat. No. 4,939,348A (Criss), having a voltage sensor lead around a perimeter of the transparency, connected at one end to a busbar extension strip on the transparency. This busbar extension strip is connected as a reference voltage to a comparator circuit. The other end of the voltage sensor lead has a terminal connected to the comparator circuit to sense a voltage difference.

[0061] The transparency of the comparative example has a voltage sensor lead connected to a busbar extension strip, rather than having an isolated conductive ring (7) according to the invention. So, the comparative example has a permanent low resistance connection to an electroconductive coating via the busbar extension strip and thus is not suitable for measuring electrical isolation from the coating. The comparative example is set up as a discontinuity detection system sensing voltage difference, in contrast to the invention which measures electrical isolation by measuring resistance or leakage current.

[0062] In an example according to the invention, as shown in FIG. 1 to FIG. 10, the conductive ring (7) is isolated from the heating element (4), suitable for measuring electrical isolation between the heating element (4) and the conductive ring (7). An electronic device (21) connected between the heating element (4) and the conductive ring (7) will reliably detect residual conductive material by, for example, applying a test voltage and measuring current flow through the electronic device (21). In this example, the electronic device (21) is a resistance meter.

[0063] In another example according to the invention, a voltage is applied to first and second busbars and the conductive ring (7) is connected to electrical ground (earth). A residual current device (RCD) connected in series with the heating element (4) serves as the electronic device (21). The RCD measures residual current, i.e. any imbalance between the current flowing from the first busbar and the current returning to the second busbar. Residual current is due to a leakage to earth via the conductive ring (7). If residual current exceeds a threshold, the RCD switches off electrical supply to the heating element (4), indicated by a circuit trip indicator (23).

[0064] In another example according to the invention, water ingress to the laminated glass (10) carrying conductive salts causes corrosion and forms a conductive path in the circumferential region (6). An electronic device (21), for example a digital ohmmeter having an indicator (23) for displaying a resistance measurement, is connected via cables (22) between the heating element (4) and the conductive ring (7). Corrosion is detected if the resistance is measurable.

KEY TO THE DRAWINGS

[0065] References in the drawings are as follows: [0066] 1, 2—First and second glass sheets [0067] 3—Ply of interlayer material [0068] 4—Heating element [0069] 5—Circumference [0070] 6—Circumferential region [0071] 7—Conductive ring [0072] 8—Gap [0073] 9a, 9b—First and second connection points [0074] 10—Laminated glass [0075] 11, 12—First and second busbars [0076] 13, 14—First and second extensions [0077] 15, 16—First and second terminals [0078] 17—Hole [0079] 18—Junction box [0080] 20—Electrical isolation measurement system [0081] 21—Electronic device [0082] 22—Cables [0083] 23—Indicator [0084] 31, 32—First, second ply of interlayer material