Vehicle glazing

Abstract

A vehicle glazing comprising a glass substrate having an electrically conductive coating deposited on at least a portion of at least one surface thereof, wherein the electrically conductive coating comprises a pyrolytically deposited transparent conductive oxide layer, wherein a peripheral obscuration band printed on at least a portion of the electrically conductive coating, a cured electrically conductive ink printed on the peripheral obscuration band, and an electrically conductive element in electrical contact with both the electrically conductive coating and the cured electrically conductive ink. Also disclosed are a method of manufacturing a vehicle glazing and a vehicle comprising said vehicle glazing.

Claims

1. A vehicle glazing comprising: a glass substrate having an electrically conductive coating deposited on at least a portion of at least one surface thereof, wherein the electrically conductive coating comprises a pyrolytically deposited transparent conductive oxide layer, a peripheral obscuration band printed on at least a portion of the electrically conductive coating, a cured electrically conductive ink printed on the peripheral obscuration band, and an electrically conductive element in electrical contact with both the electrically conductive coating and the cured electrically conductive ink, wherein the electrically conductive element comprises at least one aperture in the peripheral obscuration band to allow electrical contact between the cured electrically conductive ink and the electrically conductive coating.

2. A vehicle glazing as claimed in claim 1, wherein substantially all of the cured electrically conductive ink is printed on the peripheral obscuration band.

3. A vehicle glazing as claimed in either claim 1, wherein the electrically conductive element comprises an electrically conductive part of the peripheral obscuration band.

4. A vehicle glazing as claimed in claim 1, wherein the electrically conductive element comprises an electrically conductive fillet disposed in at least one aperture in the peripheral obscuration band.

5. A vehicle glazing as claimed in claim 1, wherein the electrically conductive ink comprises silver.

6. A vehicle glazing as claimed in claim 5, wherein the electrically conductive ink comprises an average of 40 wt % to 90 wt % silver in the ink composition before curing.

7. A vehicle glazing as claimed in claim 1, wherein the cured electrically conductive ink comprises an electrically conductive ink comprising pigment.

8. A vehicle glazing as claimed in claim 7, wherein the electrically conductive element comprises an electrically conductive fillet formed of dark electrically conductive ink disposed in at least one aperture in the peripheral obscuration band.

9. A vehicle glazing as claimed in claim 8, further comprising a second electrically conductive ink disposed so as to be in electrical contact with the first electrically conductive ink.

10. A vehicle glazing as claimed in claim 1, wherein the electrically conductive ink is thermally cured and/or is UV cured.

11. A vehicle glazing as claimed in claim 1, wherein the cured electrically conductive ink has a sheet resistance in the range 0.01 Ω/square to 1 Ω/square.

12. A vehicle glazing as claimed in claim 1, wherein the pyrolytically deposited transparent conductive oxide comprises doped tin oxide, doped zinc oxide, a stannate or a mixture of two or more of these oxides.

13. A vehicle glazing as claimed in claim 12, wherein the pyrolytically deposited transparent conductive oxide comprises tin oxide.

14. A vehicle glazing as claimed in claim 1, wherein the thickness of the pyrolytically deposited layer is in the range 50 nm to 500 nm.

15. A vehicle glazing as claimed in claim 1, wherein the electrically conductive coating has a sheet resistance in the range 5 Ω/square to 100 Ω/square.

16. A vehicle glazing as claimed in claim 1, wherein the pyrolytically deposited transparent conductive oxide layer is the outermost layer of the electrically conductive coating.

17. A vehicle glazing as claimed in claim 1, wherein the cured electrically conductive ink forms a first busbar to electrically connect the electrically conductive coating to a power supply.

18. A vehicle glazing comprising, a glass substrate having an electrically conductive coating comprising a pyrolytically deposited transparent conductive oxide layer, the coating being deposited on at least a portion of at least one surface of the glass substrate, a peripheral obscuration band printed on at least a portion of the electrically conductive coating, at least a first busbar comprising cured electrically conductive ink, the busbar being printed on the peripheral obscuration band, and an electrically conductive element in electrical contact with both the electrically conductive coating and first busbar, wherein the electrically conductive element comprises at least one aperture in the peripheral obscuration band to allow electrical contact between the cured electrically conductive ink and the electrically conductive coating.

19. A vehicle glazing as claimed in claim 17, further comprising at least a second busbar comprising cured electrically conductive ink, the second busbar being printed on a second portion of the glazing so that it is in electrical contact with at least a second portion of the electrically conductive coating.

20. A method of manufacturing a vehicle glazing, the method comprising a) providing a first glass ply coated with an electrically conductive coating comprising a pyrolytically deposited transparent conductive oxide layer, the coating being deposited on at least a portion of at least one surface of the glass substrate, b) printing a peripheral obscuration band containing at least one aperture on a peripheral portion of substrate, c) printing at least one busbar on the peripheral obscuration band using an electrically conductive ink so that it covers the aperture thereby providing electrical contact between the busbar and the electrically conductive coating, and d) curing the electrically conductive ink.

21. A vehicle having a power supply at 10 V to 250 V and comprising a vehicle glazing as claimed in claim 1.

Description

(1) The present invention will now be described by way of example only, and with reference to, the accompanying drawings, in which:

(2) FIG. 1 is a schematic plan view of the inner surface of a vehicle glazing according to the invention having a printed peripheral obscuration band.

(3) FIG. 2 is a schematic cross sectional view through the vehicle glazing of FIG. 1 on B-B.

(4) FIG. 3 is a schematic cross sectional view through a lower portion of the edge of a second vehicle glazing.

(5) FIG. 4 is a schematic cross sectional view through a lower portion of the edge of a third vehicle glazing.

(6) FIG. 5 is a schematic cross sectional view through a lower portion of the edge of a fourth vehicle glazing.

(7) FIG. 6 is a schematic plan view of the outer surface of a fifth vehicle glazing.

(8) FIG. 7 is a schematic plan view of the outer surface of a sixth vehicle glazing.

(9) FIG. 8 is a schematic plan view of the outer surface of a seventh vehicle glazing.

(10) FIG. 1 and FIG. 2 show respectively a plan view and a cross-sectional view of a vehicle glazing 2 suitable for use as a vehicle rear window. FIG. 1 is the plan view of the surface of the vehicle glazing 2 that would be inside the vehicle when installed and in use. The vehicle glazing 2 comprises float glass substrate 4 having pyrolytically deposited electrically conductive coating 6 comprising a layer of F:SnO.sub.2 on the air side surface thereof. An electrically conductive peripheral obscuration band 21 is screen printed using an ink (Chimet 3900) comprising silver (70 to 78 wt %) and carbon black in a frit on the electrically conductive coating 6 around the periphery of the glazing 2, framing the viewable area 3 of the glazing. In the lower peripheral part 8 of the vehicle glazing 2 there is a lower busbar 10 screen printed on the electrically conductive peripheral obscuration band 21. The lower busbar 10 is printed using an ink containing 70 to 78 wt % silver particles in a glass frit and subsequently thermally cured. An upper busbar 12 in the upper peripheral part 14 of the vehicle glazing 2 is screen printed in the same way. The electrically conductive coating 6 prevents the usual colour change and the lower busbar 10 and upper busbar 12 are therefore a metallic colour. The peripheral obscuration band 21 serves to obscure the upper busbar 12 and lower busbar 10 from view outside the vehicle when the glazing 2 is installed. Because the peripheral obscuration band 21 is electrically conductive, the electrically conductive coating 6 and upper busbar 12 and lower busbar 10 are in electrical contact.

(11) The peripheral obscuration band may comprise a plurality of apertures (e.g. defined portions of the peripheral obscuration band 21 that are not printed). This would be particularly advantageous if, as an alternative to the embodiment of FIGS. 1 and 2, the peripheral obscuration band was not electrically conductive (e.g. by printing using an ink comprising carbon black in a frit but with little or no silver) because it would still allow electrical contact between the busbars 10, 12 and the electrically conductive coating 6.

(12) FIG. 3 shows a schematic cross section of a portion of the edge of the lower portion of a vehicle glazing according to the invention. The vehicle glazing is generally similar to the embodiment illustrated in FIGS. 1 and 2 with a peripheral obscuration band 121. Thus, the vehicle glazing comprises a float glass substrate 4 having pyrolytically deposited electrically conductive coating 6 comprising a layer of F:SnO.sub.2. There is a lower busbar 131 screen printed on the peripheral obscuration band 121 itself screen printed using an ink comprising carbon black in a frit on the electrically conductive coating 6. The material of the peripheral obscuration band 121 is not electrically conductive but there are one or more apertures 122 so that the ink forming the busbar 131 flows into the aperture 122 forming an electrically conductive fillet 123 that makes electrical contact with the electrically conductive coating 6. Busbar 131 is printed using an ink containing 50 to 78 wt % silver particles in a glass frit. The ink of the busbar 131 is subsequently thermally cured. The electrically conductive coating 6 prevents the usual colour change and the busbar 131 is therefore a metallic colour. The peripheral obscuration band 121 serves to obscure much of the busbar 131, but the fillet 123 in the aperture 122 would be visible from outside the vehicle as a metallic shape when the glazing is installed.

(13) FIG. 4 shows a schematic cross section of a lower portion of the edge of a third vehicle glazing according to the invention. The vehicle glazing is generally similar to the embodiment illustrated in FIG. 3, but in this case busbar 131 is printed using an ink containing 50 to 78 wt % silver particles and carbon black pigment in a glass frit. The ink of the busbar 131 is subsequently thermally cured. The ink forming the busbar 131 flows into the aperture 122 during printing forming a conductive fillet 123 that makes electrical contact with the electrically conductive coating 6. Although, the electrically conductive coating 6 prevents the usual colour change, the busbar 131 is dark in colour so that the fillet 123 in the aperture 122 is less visible (and may closely match in colour the peripheral obscuration band 121) from outside the vehicle when the glazing is installed.

(14) FIG. 5 shows a schematic cross section of a lower portion of the edge of a fourth vehicle rear window according to the invention. The vehicle rear window is generally similar to the embodiment illustrated in FIG. 3, with a peripheral obscuration band 121 having one or more apertures 122. The busbar 231 is formed of a first conductive ink 233 which is printed first and flows into the apertures 122 forming a conductive fillet 223 and making electrical contact with the electrically conductive coating 6. A second conductive ink 232 is overprinted on the first conductive ink 233. The first conductive ink 233 contains 50 to 78 wt % silver particles in a glass frit with carbon black pigment. The second conductive ink forming 232 comprises 50 to 78 wt % silver particles in a glass frit. The inks of the busbar 231 are subsequently thermally cured. The peripheral obscuration band 121 serves to obscure much of the busbar 231, the conductive fillet 223 in the aperture 122 formed from dark first conductive ink 233 would be less or not visible from outside the vehicle as a dark colour against the dark peripheral obscuration band 121 when the glazing is installed.

(15) FIG. 6 is a schematic plan view of the outer surface (i.e. the surface that would be visible from outside the vehicle when the window is installed in a vehicle) of a fifth vehicle glazing 301 suitable for use as a rear vehicle window. The lower part of the vehicle glazing 301 in cross section is generally as shown in FIG. 3 and the parts of the glazing 301 illustrated there will not be described in detail. The peripheral obscuration band 121 has an upper aperture 324 and lower aperture 323 each in the form of a thin line. The upper and lower busbars are printed using an ink containing 50 to 78 wt % silver particles in a glass frit. After printing, the ink of the busbar is thermally cured. The electrically conductive coating (see FIG. 3) prevents the usual colour change and the upper and lower busbars are therefore a metallic colour. The peripheral obscuration band 121 serves to obscure most of each busbar, but the fillets making electrical connection to the electrically conductive coating are visible through the upper aperture 324 and lower aperture 323 as thin metallic appearing lines on the outside surface.

(16) FIG. 7 is a schematic plan view of the outer surface (i.e. the surface that would be visible from outside the vehicle when the window is installed in a vehicle) of a sixth vehicle glazing 302 suitable for use as a rear vehicle window. The vehicle glazing 302 is generally similar is that illustrated in FIG. 6, but the lower apertures are in the form of lines 323a and indicia 323b and so the fillets making electrical connection to the electrically conductive coating are visible through the lower apertures as lines (323a) and indicia (323b). In FIG. 7, the indicia apertures 323b are letters, but in other embodiments the indicia apertures 323b may be shaped to indicate logos, designs, names, product identifiers or similar indicators.

(17) FIG. 8 is a schematic plan view of the outer surface (i.e. the surface that would be visible from outside the vehicle when the window is installed in a vehicle) of a seventh vehicle glazing 402 suitable for use as a rear vehicle window. The vehicle glazing 402 is generally similar is that illustrated in FIGS. 6 and 7, but the lower apertures are in the form of circular apertures 323 and so the fillets making electrical connection to the electrically conductive coating are visible through the lower apertures 323 as circles. In FIG. 8, the lower apertures 323 are circles, but in other embodiments the upper 324 and/or lower apertures 323 may be generally any suitable shape (e.g. square, rectangle, oval, star, triangle, diamond, pentagon, hexagon, etc).

(18) The present invention will now be further illustrated by the Examples in which samples of vehicle glazings consisting of a glass substrate coated with an electrically conductive layers of fluorine doped tin oxide were printed with silver containing conductive ink and cured.

EXAMPLES

(19) Electrical Properties

(20) The sheet resistance of the Examples was determined using a surface resistivity meter with a 4-point probe (Guardian Model SRM 232). Measurements were taken at the same thickness for each sample, and the mean of three measurements was taken.

(21) Substrates

(22) In the Examples, the coated glass plies were of float glass coated with fluorine doped tin oxide (as the outer layer).

(23) The coated glass plies were of the form glass/undoped SnO.sub.2/SiO.sub.2/F doped SnO.sub.2 with the doped tin oxide layer to product a coated glass ply having a sheet resistance of 15 Ω/square. By varying the thickness of the doped tin oxide coating the sheet resistance may also be varied.

(24) The fluorine-doped tin dioxide layer was deposited using on-line CVD coating. This is done during the float glass production process with the temperature of the glass substrate at 600 to 650° C. A tin-containing precursor, in the form of dimethyltin dichloride (DMT), is heated to 177° C. and a stream of carrier gas, in the form of helium, is passed through the DMT. Gaseous oxygen is subsequently added to the DMT/helium gas stream. At the same time, a fluorine-containing precursor, in the form of anhydrous hydrogen fluoride (HF), is heated to 204° C. Additional water is added to create a mixture of gaseous HF and water. The two gas streams are mixed and delivered to the hot glass surface at a rate of around 395 litres/minute. The ratio of DMT to oxygen to HF is 3.6:61.3:1. The thickness of the resulting fluorine-doped tin oxide layer is approximately 320 nm and it has a nominal sheet resistance of about 15 Ω/square, measured as 12 to 13 Ω/square.

EXAMPLES

(25) Washed pyrolytically coated glasses as described above (of measured sheet resistance 12 to 13 Ω/square) were used as the substrate. Silver busbars were screen printed (using Chimet AG 3900 ink having a nominal silver content of 80 wt %) on the upper and lower peripheral portions of the rear window on the pyrolytic electrically conductive coating.

(26) After firing/curing at 680° C., cycle time 100 seconds, the printed busbars were metallic silver in colour. Busbars printed in the same way on glass substrates without the pyrolytic coating were orange after firing/curing.

(27) On the inventive samples, the metallic silver remained the same after firing and over time (more than 12 months).

(28) Samples were also produced applying printed silver busbars to the pyrolytic electrically conductive coated surface. Over 6 months, silver print remained metallic in colour. Samples were also produced by printing the substrates (using standard black ink obtained from Johnson Matthey) with obscuration bands having apertures in the form of lines. Silver busbars were screen printed (using Chimet AG 3900 ink having a nominal silver content of 80 wt %) on the peripheral obscuration bands. After firing/curing at 680° C. cycle time 100 seconds, the printed busbars were metallic silver in colour and parts of the metallic busbars were visible through the apertures in the obscuration bands.

REFERENCE NUMERALS

(29) 2 Vehicle glazing 3 Viewable area 4 Float glass substrate 6 Electrically conductive coating 8 Lower peripheral part 10 Lower busbar 12 Upper busbar 14 Upper peripheral part 21 Electrically conductive peripheral obscuration band 121 Peripheral obscuration band 122 Aperture 123 Electrically conductive fillet 131 Lower busbar 223 Electrically conductive fillet 231 Lower busbar 232 Second conductive ink 233 First conductive ink 301 Vehicle glazing 302 Vehicle glazing 323 Lower Aperture 323a Lower line aperture 323b Lower indicia aperture 324 Upper aperture 402 Vehicle glazing