WO2007077466A2

WO2007077466A2 - Glazing

Info

Publication number: WO2007077466A2
Application number: PCT/GB2007/050007
Authority: WO
Inventors: Martin Derda; Michael Lyon; Ashley Torr; Michael Greenall
Original assignee: Pilkington Automotive Deutschland GmbH; Pilkington Group Ltd; Pilkington Automotive Ltd
Current assignee: Pilkington Automotive Deutschland GmbH; Pilkington Group Ltd; Pilkington Automotive Ltd
Priority date: 2006-01-06
Filing date: 2007-01-05
Publication date: 2007-07-12
Anticipated expiration: 2008-07-06
Also published as: WO2007077466A3

Abstract

An automotive glazing comprising an interlayer laminated between first and second plies of a glazing material is disclosed. The glazing is operably associated with at least one light emitting diode. The interlayer comprises a laser-treated region of increased light transmittance to the light from the light emitting diode, relative to the light transmittance to the light from the light emitting diode o f at least part of the remainder of the interlayer. The laser-treated region results from irradiat ion with light emitted by a laser. The light emitting diode is arranged so that light from the light emitting diode can pass through the region of increased light transmittance when the light emitting diode is in use.

Description

GLAZING

The present invention relates to a glazing and, in particular, to a glazing that is suitable for use with a light emitting device, such as a light emitting diode.

Light emitting diode (LEDs) are generally used in automotive vehicles to provide displays, for example, warning lights on a dashboard. However, it is also known to use LEDs within a laminated glazing to increase the functionality of the glazing, as described in WO2004/009349, which discloses the lamination of LEDs mounted on flexible circuit boards into a glazing comprising two plies of glass having a polyvinyl butyral (PVB) interlayer laminated therebetween. Such LEDs are useful for providing an alarm or warning light display, where the LED is positioned within the glazing behind a printed indicium, and turned on and off to indicate an alarm or warning.

Such light emitting devices are generally used with clear (non-tinted) glazings. This is disadvantageous for certain glazings as the circuitry used to provide electrical current to the LED within the glazing is visible to a passenger within the vehicle containing the glazing. One solution to this problem is to use a generally opaque interlayer, for example, a coloured or tinted interlayer, within the laminated glazing in which the LEDs are laminated, to hide the circuitry. However, the generally opaque nature of the interlayer prevents effective transmission of the light emitted by the LED. This is a particular problem in using LEDs in glazings that are required to be coloured or tinted, for example, a rooflight. Although the circuitry of the LED is not visible, the low level of light transmitted through the generally opaque interlayer is insufficient to act as internal lighting for a passenger compartment in the vehicle the glazing is fitted in.

The present invention allows an alternative approach to be taken.

The present invention aims to address these problems by providing an automotive glazing comprising an interlayer laminated between first and second plies of a glazing material, the glazing being operably associated with at least one light emitting diode, the interlayer comprising a laser-treated region of increased light transmittance to the light from the light emitting diode, relative to the light transmittance to the light from the light emitting diode of at least part of the remainder of the interlayer, the laser-treated region having been irradiated with light emitted by a laser, wherein the light emitting diode is arranged so that light from the light emitting diode can pass through the region of increased light transmittance when the light emitting diode is in use.

The advantage of the glazing having a region of increased light transmittance is that the glazing can provide a lighting function, whilst the circuitry that provides current to the light source can be hidden from view by the opacity of the remainder of the glazing. Such a glazing therefore combines practicality and aesthetic appeal. By altering the light transmittance of the glazing, in particular the interlayer of a laminated glazing, it is possible to use such devices as LEDs in opaque glazings, rather than in clear glazings.

Preferably, the glazing is a rooflight, a backlight, a windscreen, a side window, a door window or an internal vehicle component.

The light emitting diodes may be bonded to the inner surface of the second ply of glazing material. In this situation, the light emitting diodes may be bonded to the inner surface of the second ply of glazing material using an electrically conductive adhesive. The second ply of glazing material may have an electrically conductive coating on its inner surface. The light emitting diodes may be bonded to tracks formed in the electrically conductive coating on the inner surface of the second ply of glazing material.

Alternatively, the light emitting diodes are housed within a conductive interlayer structure. In this case, the conductive interlayer structure preferably lies between the second ply of glazing material and the interlayer. The conductive interlayer structure may comprise a conductive substrate. The light emitting diodes may be mounted on the conductive substrate. The conductive interlayer structure may further comprise a non-conductive layer overlaying the light emitting diodes.

The glazing may comprise a solar control, heat reflective or low emissivity coating on the inner surface of the second ply of glazing material. A low emissivity coating may be included on the outer surface of the first ply of glazing material.

Preferably, the light emitting diode emits visible light. Preferably, the glazing material is annealed, semi toughened or semi tempered glass.

Preferably the interlayer is polyvinyl butyral.

The invention will now be described by way of example only, with reference to the accompanying drawings, wherein:

Figure 1 is a schematic, cross-sectional view of a first laminated glazing, comprising a plurality of light emitting devices;

Figure 2 is a schematic, cross-sectional view of a second laminated glazing, comprising a plurality of light emitting devices;

Figure 3 is a schematic, cross-sectional view of a third laminated glazing, comprising a plurality of light emitting devices and a composite interlayer;

Figure 4 is a schematic cross-sectional view of a fourth laminated glazing, comprising a plurality of light emitting devices; and

Figure 5 is a schematic cross-section illustrating where coatings may be applied to the plies forming the laminated glazings of Figures 1 to 3.

As discussed above, when using a generally opaque interlayer, for example, a coloured or tinted interlayer, within a laminated glazing in which light sources are laminated, as internal lighting for a vehicle, the low level of light transmitted through the generally opaque interlayer is insufficient to act as internal lighting for a passenger compartment in the vehicle in which the glazing is fitted. In other words, this is the situation where the interlayer has an opacity to the light emitted by the LED, such that the light transmittance of the glazing to the wavelength of light emitted by the LED is limited. One solution to this problem is to provide regions within the interlayer which have a reduced opacity to the light emitted by the LED, and therefore an increased transmittance to the light emitted by the LED. This enables the light to be seen through the generally opaque interlayer. In accordance with the present invention, this is done by using a laser to decolourise selected, discrete regions of the interlayer sufficiently that the light emitted by the LED provides satisfactory lighting for the passenger compartment of the vehicle.

In order to decolourise regions of the interlayer, a suitable laser wavelength needs to be chosen. PVB interlayers are often tinted using a liquid dye or a solid pigment. A spectrophotmeter may be used to select a wavelength of laser light that may be absorbed by the pigment or dye used to tint the interlayer. Once a preferred wavelength has been selected, the laser parameters necessary to optimise the intensity and/or duration of laser treatment can be optimised. This should be done bearing in mind the point that the laser treatment should not cause any substantial damage that outweigh the benefits obtained by treatment. Thus, for example, it is preferred that the treatment does not cause substantial delamination (i.e. delamination that would seriously impair the function of the laminated glazing). Delamination can be detected by inspecting a laminated glazing sample following laser treatment (e.g. by eye or with a microscope). If substantial delamination is observed then the duration and/or intensity of laser treatment can be reduced. It is also preferred that the laser treatment does not result in the formation of visible bubbles in the interlayer, especially for applications where aesthetic appearance is important. The laser pulse width, pulse frequency, power and spot size should be adjusted to ensure the intensity and duration of treatment are suitable for the material being treated.

The actual duration of treatment will largely depend upon the area, nature and depth of material to be treated.

The following examples illustrate the use of laser treatment to decolourise an interlayer in a laminated glazing, such as a rooflight for an automotive vehicle.

Figure 1 shows a cross-section of a laminated glazing 100 comprising a first ply 110 and a second ply 120 of glass, having a generally opaque PVB (polyvinyl butyral) interlayer 130 laminated therebetween. A plurality of light emitting devices 140 (LEDs) are positioned on the inner surface of the second ply of glass 120. The LEDs 140 are bonded to the inner surface of the second ply 120 using a conductive adhesive. Laser etched conductive tracks (not shown) are provided on the inner surface of the second ply of glass 120 to supply an electrical connection to the LEDs 140. Alternatively, the LEDs 140 may be soldered onto the conductive tracks. The conductive tracks may be formed from a coating already present on the surface of the glass ply 120, which itself has additional properties, for example, a silver- based reflective coating. Alternatively, the electrically conductive tracks may be printed on the inner surface of the second ply of glass 120.

In the region of each LED 140, the generally opaque interlayer 130 has been treated with a laser to provide a region 150 that is substantially clear, and therefore the light transmittance to the light emitted by the LED compared with that of the remainder of the interlayer. Each region 150 enables the light emitted by the LEDs 140 to be transmitted through the interlayer 130, creating a series of visible point light sources within the glazing 100, when the interlayer 130 is placed over the LEDs 140. The generally opaque interlayer has a LT, measured using CIE Illuminant A in the range 10% - 40%. The substantially clear region preferably has a LT approaching that of clear glass (88% for 2.1mm thick glass measured using CIE Illuminant A). Preferably, the increase in light transmittance (LT) achieved by the laser treatment is at least 10%, preferably 40%.

Figure 2 shows an alternative embodiment, where the laminated glazing 200 comprises a first 210 and a second 220 ply of glass, having a generally opaque PVB interlayer 230 laminated therebetween. A plurality of light emitting devices 240 are formed within a conductive interlayer structure 250, comprising a PET (polyethylene terephthalate) carrier substrate to which the LEDs are attached, for example, by bonding with adhesive and/or soldering, and a cover layer. Power is provided to the LEDs by either conductive tracks formed on the substrate, for example, by printing, or by laser etching tracks in a conductive coating on the substrate surface.

Again, in the regions of the LEDs 240, the generally opaque PVB interlayer 130 has been treated with a laser to provide a region 260 that is substantially clear. Each region 260 enables the light emitted by the LEDs 240 to be transmitted through the interlayer 230, creating a series of visible point light sources within the glazing 200, when the interlayer 230 is placed over the LEDs 240.

Figure 3 shows a further alternative embodiment, where the laminated glazing 300 comprises a first ply of glass 310 and a second ply of glass 320. A trilayer interlayer structure 330 is laminated between the first 310 and second 320 glass plies. The trilayer interlayer structure 330 comprises a first, clear, PVB interlayer 331, a PET interlayer 332 and a second, generally opaque, PVB interlayer 333. LEDs 340 are mounted on the PET interlayer 332, which acts as a substrate, for example, by bonding with adhesive or soldering. Power is provided to the LEDs by either conductive tracks formed on the substrate, for example, by printing, or by laser etching tracks in a conductive coating on the substrate surface. The generally opaque interlayer 333 has been treated with a laser to provide a region 350 that is substantially clear. Each region 350 enables the light emitted by the LEDs 340 to be transmitted through the generally opaque inter layer 333, creating a series of visible point light sources within the glazing 300, when the generally opaque interlayer 333 is placed over the LEDs 340. The PET interlayer on which the LEDs are mounted may also comprise a cover layer over the LEDs, as shown in Figure 2.

Such glazings are particularly useful as rooflights in automotive vehicles, such as cars, as LEDs which emit light in the visible region of the electromagnetic spectrum can be used as point sources of light for interior lighting. The generally opaque interlayer is typically a dark- coloured or tinted PVB interlayer. Unless laser treated, this reduces the amount of light entering the passenger compartment of the vehicle. However, the use of a dark PVB obscures the electrical connections and conductive tracks used to connect the LEDs. Such glazings may also be used as windscreens, backlights, side windows, door windows and internal vehicle components, such as dashboards. In some cases, such as windscreen and backlights, only a portion of the interlayer may be generally opaque, for example, a shadeband and the remainder of the interlayer clear. This allows LEDs to be positioned in the shadeband while maintaining sufficient visible area to satisfy light transmission standards.

Preferably, the PVB used is a single layer PVB having a thickness of 0.76 mm. However, alternative thicknesses of PVB may be used, as long as the rooflight maintains the impact resistance and structural integrity required by international standards. In the case of the embodiment shown in Figure 3, the first, clear PVB interlayer is preferably 0.38mm in thickness, although any other suitable thickness of PVB may be used. As an alternative to clear PVB, a generally opaque PVB (such as a coloured or tinted PVB) may be used instead.

Other suitable polyvinyl aldehydes can also be used in place of or as well as the PVB interlayers described above. Although PET is preferred for the substrate on which the LEDs are mounted, any other suitable, flexible plastics material may be used. The substrate itself may be conductive and have other useful properties. For example, the substrate may be a Siglasol™ interlayer, which comprises a PET substrate having an electrically conductive coating, which also provides solar control. Typically such an interlayer is laminated between two plies of a PVB interlayer, which may both have a thickness of 0.38 mm. If a triple glazed structure is required, the PET substrate may be replaced with a glass ply. Suitable tinted or coloured interlayers are available from manufacturers such as DuPont, Solutia and Sekisui Chemical Co.. For example, a PVB interlayer giving the same optical and thermal properties as Galaxsee™ glass may be used.

The interlayer itself may comprise several individual interlayers selected to give particular qualities or characteristics to the glazings. Figure 4 comprising a plurality of light emitting devices, and having a composite interlayer, which has been treated by a method of the present invention. The laminated glazing 400 comprises a first ply of glass 410 and a second ply of glass 420. Three interlayers 430, 440 and 450 are laminated between the first and second plies of glass 410 420. The first interlayer 430 is a coloured or tinted interlayer. The second interlayer 440 is a clear interlayer, but acts to absorb infra-red radiation (such as that available from Sekisui Chemical Co. Ltd). The third interlayer 450 is a clear interlayer. A coating 460 is provided on the inner surface of the second ply of glass 420, and has conductive tracks 462 provided, as well as a bus bar 464, for connection to a series of LEDs 470. Bleached or decolourised areas 480 of the first interlayer 430 are aligned with individual LEDs to enable light to be transmitted through the tinted or coloured PVB interlayer material.

In an alternative construction, the second, infra red reflective, interlayer 440 may be replaced with an interlayer that acts to diffuse the light emitted by the LEDs, for example, a semi- opaque interlayer.

The interlayer may be treated with the laser prior to lamination, subsequently aligned with the LEDs, and laminated. Alternatively, the glazing may be treated with the laser after lamination.

The glass plies 120 220 320 used to form the glazing may be formed of clear glass, with the plies being typically annealed, semi-toughened or semi-tempered. Alternatively, at least one ply of glass may be of a coloured or tinted glass. If coloured or tinted glass is used to form the plies, the PVB used in the glazing may be colour matched to it. For example, if the first ply of glass is coloured, the second ply of glass may be clear, with an optional coating, and the interlayer may be clear or coloured to match the first ply of glass. The glass used to form the glazing may also be bent before the LEDs are applied. Alternative glazing materials, such as sheets of polycarbonate, may be used in place of plies of glass. Suitable thicknesses for the glass plies are in the range 1 mm to 5 mm. Typical rooflight constructions use two plies of 2.1 mm thick glass, or two plies of 3.15 mm glass. The glass plies do not need to be of the same thickness if an asymmetric construction is required, for example, one ply of glass may have a thickness of 2.1 mm and the other 1.6 mm.

Various coatings may be provided on the inner surface of the outer ply of glass as shown in Figure 5. Figure 5 shows a schematic cross-section of a laminated glazing 500, of the same basic construction as glazings 100, 200, 300, 400. First 510 and second 520 plies of glass are laminated together with an interlayer 530 in between. A first coating 540 is provided on the inner surface of the second ply of glass. A second coating 550 may be provided on the outer surface of the first ply of glass. In most cases, a coating is provided only on the inner surface of the second ply of glass. LEDs (not shown) are provided on the surface of the first coating 540, with areas of the interlayer 530 being declourised to allow light transmission from the LEDs.

Suitable coatings include low-emissivity coatings, conductive coatings and solar control coatings. A low emissivity coating is a coating which when applied to clear, 3mm thick float glass, results in the coated glass having an emissivity in the range of 0.05 to 0.45, the actual value being measured in accordance with EN 12898 (a published standard of the European Association of Flat Glass Manufacturers). Hard coatings generally have emissivities between 0.15 and 0.2, whereas off-line coatings generally have emissivities of 0.05 to 0.1. As a comparison, uncoated 3mm thick float glass has an emissivity of 0.89.

A hard (or pyrolytic) low emissivity coating may comprise a single layer of a metal oxide, preferably a transparent, electrically conductive oxide. Oxides of metals such as tin, zinc, indium, tungsten and molybdenum may be present in the metal oxide layer. Typically, the coating comprises a further dopant, such as fluorine, chlorine, antimony, tin, aluminium, tantalum, niobium, indium or gallium, for example, fluorine-doped tin oxide or tin-doped indium oxide may be used. Such coatings are generally provided with an underlayer, such as silicon or silicon oxynitride. The underlayer acts as a barrier to control migration of alkali metal ions from the glass and/or to suppress iridescent reflection colours caused by variations in thickness of the low emissivity layer.

Off-line (typically sputtered) low emissivity coatings typically comprise a multilayer coating stack, normally including at least one metal layer or electrically conductive metal compound layer, and a dielectric layer. Silver, gold, copper, nickel or chromium may be used as the metal layer, whereas indium oxide, antimony oxide or the like may be used as the electrically conductive compound. Typical multilayer stacks comprise one or two layers of silver deposited between layers of a dielectric such as an oxide of silicon, aluminium, titanium, vanadium, tin, or zinc. Individual layers of such coatings are typically tens of nanometres in thickness.

Typical solar control coatings comprise layers of silver or tin oxide, and control the amount of heat absorbed through the coated glass. Solar control and low emissivity coatings may also be electrically conductive, and so not only provide functionality to the glass in terms of emissivity and heat transmission, but can form an electrically conductive substrate for mounting the LEDs. Such electrically conductive coatings may be etched using a laser to provide conductive tracks for providing electric current to the LEDs.

Heat reflective coatings, which have an element of solar control, for example, a two-layer silver coating, may also be used. Typically, the heat reflected by such coatings is greater than 23%. Metallic heat reflective coatings may also be electrically conductive, and are particularly useful if the outer ply of glass is of clear glass.

Low emissivity coatings may also be provided on the outer surface 550 of the first ply of glass. This surface will form the inside of the glazing when fitted in a vehicle, and is often known as "surface 4". This is particularly advantageous if the glass used to form the glazing is to be shaped using an advanced press bending process, where it is desirable to press two symmetric plies of glass. An additional low emissivity coating, for example, prevents re- radiation of heat within the vehicle, when the glass laminate absorbs heat from the sun.

Additional functional devices can also be included within the glazing, and may require additional decolourised regions within the generally opaque interlayer in order to transmit or receive a signal. For example, devices that act as rain, light and humidity sensors, solar devices such as solar cells, other types (non-light emitting) diodes, cameras and night vision detectors may be used. Furthermore, although the above examples use LEDs emitting light in the visible region of the electromagnetic spectrum (wavelengths in the range 38Onm to 780nm), LEDs which emit in other regions of the electromagnetic spectrum, for example, infra red or ultra violet, may be used for other applications involving signal transmission. Laser decolourisation may be used to treat glazings, in particularly interlayers, to provide transmission windows for IR and UV LEDs and light sources in the same way as for visible light. The LED or light source may be contained within another device, such as a rain sensor.

Although the above technique is described in relation to bleaching or decolourising areas of tinted or coloured PVB, it may also be used to bleach or declourise areas of tinted or coloured glass, enabling LEDs to be used in glazing constructions where an interlayer of clear PVB is laminated between two plies of coloured or tinted glass.

Claims

1. An automotive glazing comprising an interlayer laminated between first and second plies of a glazing material, the glazing being operably associated with at least one light emitting diode, the interlayer comprising a laser-treated region of increased light transmittance to the light from the light emitting diode, relative to the light transmittance to the light from the light emitting diode of at least part of the remainder of the interlayer, the laser-treated region having been irradiated with light emitted by a laser, wherein the light emitting diode is arranged so that light from the light emitting diode can pass through the region of increased light transmittance when the light emitting diode is in use.

2. A glazing according to claim 1, wherein the glazing is a rooflight, a backlight, a windscreen, a side window, a door window or an internal vehicle component.

3. A glazing according to claim 1 or 2, wherein the light emitting diodes are bonded to the inner surface of the second ply of glazing material.

4. A glazing according to claim 3, wherein the light emitting diodes are bonded to the inner surface of the second ply of glazing material using an electrically conductive adhesive.

5. A glazing according to claim 3 or 14, wherein the second ply of glazing material has an electrically conductive coating on its inner surface.

6. A glazing according to claim 5, wherein the light emitting diodes are bonded to tracks formed in the electrically conductive coating on the inner surface of the second ply of glazing material.

7. A glazing according to any of claims 1 to 6, wherein the light emitting diodes are housed within a conductive interlayer structure.

8. A glazing according to claim 7, wherein the conductive interlayer structure lies between the second ply of glazing material and the interlayer.

9. A glazing according to claim 7 or 8, wherein the conductive interlayer structure comprises a conductive substrate.

10. A glazing according to claim 9, wherein the light emitting diodes are mounted on the conductive substrate.

11. A glazing according to claim 9 or 10 wherein the conductive interlayer structure further comprises a non-conductive layer overlaying the light emitting diodes.

12. A glazing according to any of claims 1 to 11, wherein the glazing comprises a solar control, heat reflective or low emissivity coating on the inner surface of the second ply of glazing material.

13. A glazing according to claim 12, comprising a low emissivity coating on the outer surface of the first ply of glazing material.

16. A glazing according to claim 1, where in the light emitting diode emits visible light.

17. A glazing according to any of claims 1 to 16, wherein the glazing material is annealed, semi toughened or semi tempered glass.

18. A glazing according to any of claims 1 to 17, wherein the interlayer material is polyvinyl butyral.