GB2445841A

GB2445841A - Vehicle sunroof

Info

Publication number: GB2445841A
Application number: GB0800013A
Authority: GB
Inventors: Ashley Carl Torr
Original assignee: Pilkington Automotive Ltd
Current assignee: Pilkington Automotive Ltd
Priority date: 2007-01-16
Filing date: 2008-01-02
Publication date: 2008-07-23
Also published as: GB0700803D0; GB0800013D0

Abstract

A vehicle glazing assembly, e.g. a sunroof, comprising a glazing panel 11 with a variable transmission layer, e.g. a liquid crystal film (see Figure 2), the optical transparency of which is temperature dependent such that the layer is optically transparent above a switching temperature. A covering 13 moves relative to the glazing panel 11 between a first position in which at least a portion of the glazing panel 11 is exposed, and a second position in which a smaller portion is exposed or the glazing panel is covered. A sensor 14, in electrical communication with the covering 13, senses when a temperature below or equal to the switching temperature has been reached and subsequently provides a signal to either: a) initiate automatic movement of the covering 13 from the first position to the second position, or b) prevent manual movement of the covering 13 from the second position. Also disclosed is a glazing panel, preferably a laminate, comprising a variable transmission layer, e.g. a liquid crystal film, for use in such an assembly.

Description

VEHICLE GLAZING ASSEMBLY & GLAZING PM4EL FOR USE THEREIN The present

invention relates to a vehicle glazing assembly comprising a glazing panel capable of variable transmission, and to a glazing panel comprising a variable transmission layer for use in such an assembly.

In the field of automotive glazings, it is known to provide a glazing which comprises a variable transmission layer, such as a liquid crystal layer, a layer comprising a suspended particle device, an electrochromic layer, to name but a few. For example, WO 02/072408 discloses a liquid crystal film in an automotive rooflight (roof window glazing) which is used to control the amount of light passing through the glazing when it is switched to its non-transparent state.

Unfortunately, certain types of variable transmission materials considered for use to make such layers appear to exhibit temperature dependent optical transparency, which may or may not be reversible. This means that for these materials, once a particular temperature is reached, hereinafter referred to as a switching temperature (which is material-specific), the material will be optically transparent, regardless of whether or not an external influence (such as an electrical current), which would otherwise alter the transmissivity of the material, is applied. By "optical transparency" (and related phrases), it is meant that the material loses its ability to switch to a darker or opaque state when an electric field is applied and remains transparent to visible light.

For a vehicle installed with one or more glazings which comprise a reversible, temperature dependent variable transmission layer, if the ambient temperature of the environment surrounding the vehicle is such that the temperature of the layer is often likely to reach and exceed the switching temperature, the layer will become and remain transparent until its temperature drops below the switching temperature. Obviously frequent occurrences of such behaviour are not acceptable, and even on an infrequent basis, this behaviour is highly undesirable. This is because with each occurrence of forced transparency, the desired facility to vary the transmission of the glazing is temporarily lost.

Despite such a significant drawback, it would however still be desirable to provide a vehicle glazing which comprises a variable transmission layer.

Accordingly in a first aspect the present invention provides a vehicle glazing assembly comprising a glazing panel including a variable transmission layer, the optical transparency of said layer being temperature dependent such that the layer is optically transparent above a switching temperature, a covering adapted to move relative to the glazing panel between a first position in which at least a portion of the glazing panel is exposed, and a second position in which a smaller portion is exposed or the glazing panel is covered, and a sensor, in electrical communication with the covering, capable of sensing when a temperature below or equal to the switching temperature has been reached and subsequently providing a signal to either: a) initiate automatic movement of the covering from the first position to the second position, or b) prevent manual movement of the covering from the second position.

Provision of a vehicle glazing assembly as described above means that a vehicle may be equipped with one or more variable transmission glazings, despite the fact that the variable transmission material used in the glazing may exhibit reversible optical transparency. Having such a variable transmission glazing in an assembly as described means that when the variable transmission layer is at a temperature below its switching temperature, the variable transmission facility can be utilised. I lowever when the variable transmission layer is at a temperature above its switching temperature, the covering is automatically moved to cover most or all of the glazing panel, or if the covering is already "closed" over the glazing panel, it cannot be moved and "opened".

The covering may be in the form of a blind, which may itself be non-transparent, of the type currently to be found in a vehicle for covering over a "sun-roof". Ordinarily, the covering may be mounted in a frame, to which the glazing panel may be secured (the glazing panel itself may nonetheless be open-able relative to the frame). The frame may be the bodywork of the vehicle into which the assembly is fitted.

In the first position, the glazing panel may be entirely exposed, e.g. the covering may be completely retracted, or only a part of it may be exposed, e.g. if the variable transmission layer only partially extends over the glazing, only that part may be exposed.

Correspondingly, in the second position a smaller portion of the glazing panel may be exposed, meaning that an optically transparent area of the glazing panel may be exposed, or the covering may be fully extended to completely cover the glazing panel.

The function of the sensor is to detect when the temperature of the variable transmission layer has reached or exceeded its switching temperature, and to provide a signal to activate a responsive action (though this may occur at a predetermined temperature below, preferably just below, e.g. 2 to 3 degrees Centigrade below, the switching temperature). Depending on the location of the covering relative to the glazing panel, this action may be as per (a) above, e.g. automatic closure of the covering over the glazing panel, or (b) above, e.g. prevention of manual opening of the covering from its closed position over the glazing panel.

The sensor may be in electrical communication with the covering via a mechanical mechanism, which is able to control movement of the covering. In case (a) the mechanism may be activated to move the covering and in case (b) it may be activated as a barrier or brake to prevent movement of the covering. Typically the covering may undergo lateral, sliding movement relative to the glazing panel.

Preferably the variable transmission layer comprises a liquid crystal film. A liquid crystal film may diffuse visible light passing through it as well as attenuating it. The liquid crystal film may be electrically switchable between a clear state (resulting from a voltage being applied to the film) and an opaque state (having no voltage applied). The degree to which visible light passing through a liquid crystal film is attenuated and diffused may be controlled by regulation of the voltage applied to the film.

Advantageously, the liquid crystal film may be divided into zones, and each zone may be independently switchable. Any known liquid crystal film material may be used, provided that it is suitable for inclusion in a vehicle glazing.

Preferably the switching temperature is greater than 65 C. Further preferably the switching temperature is around 70 C to 75 C. However, the switching temperature may be as high as around 90 C. Thus it may only be in hotter climates that the temperature dependent reversible optical transparency is observed and troublesome.

Preferably the sensor is a temperature sensor. Advantageously the sensor is additionally capable of sensing when the temperature of the variable transmission layer has dropped from or above, to below, the switching temperature and subsequently providing a signal to either: a) initiate automatic movement of the covering from the second position to the first position, or b) allow manuai movement of the covering from the second position.

This additional function of the sensor means that it is capable of activating a second responsive action, which may effectively reverse the result of the first responsive action discussed earlier. Depending on the location of the covering relative to the glazing panel, this second action may be as per (a) directly above, e.g. automatic opening of the covering to expose the glazing panel, or (b) directly above, e.g. allowance of manual opening of the covering from its closed position over the glazing paneL When installed in a vehicle, a vehicle glazing assembly as herein described may have the glazing panel located on the exterior of the vehicle and the covering located on the interior of the vehicle. This configuration may be especially useful when the covering is in the form of a blind, as discussed earlier.

A vehicle glazing assembly according to the present invention may be used to glaze any opening in the bodywork of a vehicle. It may especially be used to glaze a roof window opening in a vehicle.

In a second aspect, the present invention provides a glazing panel, for use in a vehicle glazing assembly as herein described, comprising at least one pane of glazing material, and a variable transmission layer associated with it, the optical transparency of said layer being temperature dependent such that the layer is optically transparent above a switching temperature.

The variable transmission layer may comprise a liquid crystal film.

Preferably the sensor is capable of sensing when a temperature (just) below or equal to the switching temperature has been reached. The switching temperature may typically be greater than 65 C, preferably around 70 C to 75 C, and possibly around C. The sensor itself may be a temperature sensor. Furthermore the sensor may be additionally capable of sensing when the temperature of the variable transmission layer has dropped from or above, to below, the switching temperature and subsequently providing a signal to either: a) initiate automatic movement of the covering from the second position to the first position, or b) allow manual movement of the covering from the second position.

The glazing panel is preferably a laminate comprising two panes of glazing material having a ply of laminating interlayer material between them, and the variable transmission layer may be positioned within the laminate. The variable transmission layer may be provided as the ply of laminating mterlaycr material or it may be interleaved between two plies of laminating interlayer material to form a composite interlayer. The laminating interlayer material may be any material known in the art that is suitable for forming a laminate. It may be polyvinyl butyral ("PVB"), polyvinyl chloride ("PVC"), polyurethane ("PU") or an ethyl vinyl acetate ("EVA"). It is typically provided in a thickness of between 0.38 and 1.1 mm, but most commonly 0.76 mm. The interlayer material may bc clear, body-tinted or it may be infrared absorbing or reflecting (thereby contributing to the solar control function of the glazing).

Preferably the panes of glazing material are body-tinted, which may be in addition to or instead of the ply of laminating interlayer material being body-tinted. At least one of the panes of glazing material may be body-tinted glass, the composition of which includes one or more of the following colourants: iron oxide, cobalt oxide, selenium, chromium oxide, titanium oxide, manganese oxide, copper oxide, vanadium oxide, nickel oxide. The tint may be such that the glass absorbs an amount of infrared radiation, providing further solar control.

Both panes of glazing material may be panes of glass, and if only one pane is body-tinted, the other pane may be clear. It is also possible that both panes may be clear glass, or both panes may be body-tinted. One or both panes may be toughened or semi-toughened glass. Rather than being a pane of glass, a pane of glazing material may be made from a plastics material, for example polycarbonate. The panes of glazing material may be flat or they may be curved. Each pane may be between 0.5 and 25 mm in thickness, preferably between I and 5 mm. The overall thickness of the glazing may therefore be between 1.5 and 100 mm, preferably between 2 and 50 mm, and further preferably between 2.5 and 20 mm.

One or more of the panes of glazing material may further have an infrared reflecting coating applied to one or more of its surfaces, preferably on surface 2 and/or surface 3 (the inner surface of the outer pane ("outer" with respect to a vehicle into which the glazing panel may be installed) and the inner surface of the inner pane respectively).

Furthermore a low emissivity coating may be provided on surface 4 (the innermost surface of the glazing panel). Any infrared reflecting coating and any low emissivity coating known in the art may be used. Moreover, the glazing panel may also include one or more infrared absorbing films; again any such film known in the art may be used.

When the variable transmission layer is transparent (e.g. as a result of having a voltage applied, or because of its temperature dependency), the glazing may have a visible light transmission (measured with CIE Illuminant A) of greater than 70 % and further preferably greater than 75 % when the panes of glazing material are substantially clear, e.g. when they are panes of clear glass having a total iron oxide content of ca. 0.1 % by weight). If the glazing overall has a tint (because either at least one pane of glazing material is body-tinted or the interlayer material is tinted), it preferably has a visible light transmission (measured with CIE Illuminant A) of less than 40 %, further preferably less than 30 % and most preferably less than 25 %, and a total energy transmission (Parry Moon; Air Mass 1.5) of less than 30 %, further preferably less than 25 % and most preferably less than 20 %.

For a better understanding the present invention will now be more particularly described by way of non-limiting example with reference to, and as shown in, the accompanying schematic drawings wherein: Figure 1 is a perspective view of a vehicle glazing assembly according to the invention; and Figure 2 is a cross section of the glazing panel in Figure 1 as viewed along line A-A.

Figure 1 shows a vehicle glazing assembly 10 comprising a glazing panel 11 secured in a frame 12, a covering 13 mounted below glazing panel 11, and a temperature sensor 14. Glazing panel II is a laminated glazing, the construction of which is shown in more detail in Figure 2.

Figure 2 shows that glazing panel 11 comprises an outer pane of glazing material 21, in the form of a pane of glass, an inner pane of glazing material 22, also in the form of a pane of glass, and composite interlayer 23 between panes of glazing material 21,22.

Composite interlayer 23 comprises a variable transmission layer 24, in the form of a liquid crystal film having reversible, temperature dependent optical transparency (its switching temperature being approximately 75 C), which is bordered by a ply of laminating interlayer material 25 in a "picture frame" design and also interleaved between two further plies of laminating interlayer material 25, each being in the form of a ply of PVB. By "outer pane" is meant the pane which contacts the environment external to a vehicle into which vehicle glazing assembly 10 may be fitted; similarly, by "inner pane" is meant the pane which contacts the interior environment of said vehicle.

A pane of soda lime silica glass may be clear glass and have a composition in the range (by weight): Si02 68 -75 %; Al2O 0 -5 %; Na20 10 -18 %; K20 0 -5 %; MgO o -10 %; CaO 5 -15 %; SO3 0 -2 %. The glass may also contain other additives, for example, refining aids, which would normally be present in an amount of up to 2 %. One or more of the panes may be tinted glass (thereby contributing to the solar control function of glazing panel 11) having, for example, the following composition: -base glass (by weight): 72.1 % Si02, 1.1 % Al203, 13.5 % Na20, 0.6 % 1(O, 8.5 % CaO, 3.9% MgO and 0.2 % SO3, and -colourant portion (by weight): 1.45 % total iron (calculated as Fe203), 0.30 % ferrous oxide (calculated as FeO), 230 ppm Co304, 210 ppm NiO and 19 ppm Se.

Such a glass is currently available as GALAXSEE'M from Pilkington Group Limited, Prescot Road, St Helens, Merseyside WAI 0 3TT, United Kingdom (www.pilkington.com).

Glazing panel 11 is secured within frame 12 -in this example, frame 12 is the bodywork of the vehicle into which assembly 10 is installed, and in particular, frame 12 is formed from the roof portion of the bodywork. Although glazing panel 11 is secured within frame 12, it may nonetheless be open-able (e.g. by sliding open, or tilting open), as is known in the art for conventional vehicle "sun-roof' windows.

Covering 13 is in the form of a roof blind, of a type currently to be found in vehicles fitted with "sun-roof' windows, and as such is non-transparent. Covering 13 is mounted below glazing panel 11 and inside frame 12, and is slidable relative to both in the directions shown by the double-headed arrow in Figure 1. Covering 13 is shown in a first position in which a portion of glazing panel 11 is exposed. Lateral movement to the left by covering 13 would take it to a second position in which a smaller portion of glazing panel 11 would be exposed or glazing panel 11 would be completely covered.

Movement of covering 13 may be achieved automatically in response to an initiating signal sent from temperature sensor 14 once it has sensed that the switching temperature of variable transmission layer 24 (or a temperature just a few degrees Centigrade below the switching temperature) has been reached or exceeded.

Temperature sensor 14 is shown as being located on frame 12, specifically on its outer surface. It could however be located elsewhere on the vehicle, provided it is able to accurately sense when a temperature equal to the switching temperature of layer 24 (or a temperature just a few degrees Centigrade below) has been reached (and subsequently when the temperature drops back below the switching temperature). Sensor 14 is in electrical communication with covering 13 via a mechanical mechanism (not shown) which controls movement of covering 13 in response to the appropriate signal from sensor 14.

In the case where glazing panel 11 is constructed from two panes of 3 mm thickness clear glass 21,22 having a composite interlayer 23 laminating the two together (composite interlayer 23 comprising a 0.4 mm thickness liquid crystal film 24, bordered by a 0.38 mm thickness ply of PVB 25 and interleaved between two further plies of PVB 25, each of 0.76 mm thickness), it has in its active area (that covered by liquid crystal film 24) a visible light transmission of 76 % (CIE Illuminant A) and a total energy transmission (Parry Moon; Air Mass 1.5) of 64 % when liquid crystal film 24 is electrically switched on, and a visible light transmission of 48 % (CIE Illuminant A) and a total energy transmission (Parry Moon; Air Mass 1.5) of 44 % when liquid crystal film 24 is not electrically powered (it is effectively opaque). Such a liquid crystal film 24 may be obtained from NSG UMU Products Co. Ltd., 1-7 2-chome, Kaigan, Minato-ku, Tokyo, Japan (www.nsg.co.jp/uniu).

Once installed as part of assembly 10 in a vehicle, when a temperature 2 to 3 degrees Centigrade below the switching temperature of liquid crystal film 24 (around C) is reached, temperature sensor 14 will sense this event and subsequently provide a signal to initiate automatic movement of covering 13 from its position shown in Figure 1 to a more closed or altogether closed position, thereby ensuring the comfort of passengers within the vehicle.

Claims

Claims: I. A vehicle glazing assembly comprising a glazing panel

including a variable transmission layer, the optical transparency of said layer being temperature dependent such that the layer is optically transparent above a switching temperature, a covering adapted to move relative to the glazing panel between a first position in which at least a portion of the glazing panel is exposed, and a second position in which a smaller portion is exposed or the glazing panel is covered, and a sensor, in electrical communication with the covering, capable of sensing when a temperature below or equal to the switching temperature has been reached and subsequently providing a signal to either: a) initiate automatic movement of the covering from the first position to the second position, or b) prevent manual movement of the covering from the second position.
2. A vehicle glazing assembly as claimed in claim 1 wherein the variable transmission layer comprises a liquid crystal film.
3. A vehicle glazing assembly as claimed in claim I or claim 2 wherein the predetermined temperature is greater than 65 C.
4. A vehicle glazing assembly as claimed in claim 3 wherein the predetermined temperature is around 70 to 75 C.
5. A vehicle glazing assembly as claimed in any preceding claim wherein the sensor is a temperature sensor.
6. A vehicle glazing assembly as claimed in any preceding claim wherein the sensor is additionally capable of sensing when the temperature of the variable transmission layer has dropped from or above, to below, the switching temperature and subsequently providing a signal to either: a) initiate automatic movement of the covering from the second position to the first position, or b) allow manual movement of the covering from the second position.
7. A vehicle glazing assembly as claimed in any preceding claim in which, when installed in a vehicle, the glazing panel is located on the exterior of the vehicle and the covering is located on the interior of the vehicle.
8. Use of a vehicle glazing assembly as claimed in any preceding claim to glaze a roof window opening in a vehicle.
9. A glazing panel, for use in a vehicle glazing assembly as claimed in claim 1, comprising at least one pane of glazing material, and a variable transmission layer associated with it, the optical transparency of said layer being temperature dependent such that the layer is optically transparent above a switching temperature.
10. A glazing panel as claimed in claim 9 further comprising a sensor capable of sensing when a temperature below or equal to the switching temperature has been reached.
11. A glazing panel as claimed in claim 9 or claim 10 wherein the glazing panel is a laminate comprising two panes of glazing material having a ply of laminating interlayer material between them, and the variable transmission layer is positioned within the laminate.
12. A glazing panel as claimed in claim I I wherein the panes of glazing material are body-tinted and/or the ply of laminating interlayer material is body-tinted.
13. A vehicle glazing assembly substantially as hercinbefore described with reference to, and as illustrated in, Figure 1 of the accompanying drawings.

II
14. A glazing panel substantially as hereinbefore described with reference to, and as illusfrated in, Figures 1 and 2 of the accompanying drawings.