Lighting vehicle glazing

Abstract

The present invention relates to a lighting vehicle glazing (1) comprising an external glass pane having an outer surface (P1) and an inner surface (P2) and an internal glass pane having an inner surface (P3) and an outer surface (P4) and having at least one edge, acting as a light guide layer, and the external and the internal glass panes being laminated together via at least an interlayer, the external and the internal glass panes being curved and having a radius of curvature (r), a light source provided in the vicinity of the edge of the outer surface (P4) of the internal glass pane, at least one coupling element provided in the vicinity of the light source, and optically bonded to the internal glass pane on its outer surface (P4), that couples the light emitted from the light source into the internal glass pane, the coupling element having a width parallel to the edge of the internal glass pane.

Description

LIGHTING VEHICLE GLAZINGFIELD OF THE INVENTION

[0001] The present invention relates to a lighting glazing unit for vehicles, particularly a lighting glazing forming part of the roof of a vehicle. More particularly a light source provided therein illuminates the vehicle laminated glazing. Such a vehicle window is known from practice and can be used in particular in the field of a vehicle roof.BACKGROUND OF THE INVENTION

[0002] It is known from prior art that in lighting vehicle glazings, the glass pane acts as a light guide layer. It is also known that the light from a glazed roof provided with a light source can be coupled to a light guide layer. For safety of passengers of the vehicle, the glazing is a laminated glazing provided with an external and an internal glass pane. It is well known that a coupling element is provided on an edge of the internal glass pane acting as a light guide layer. The internal glass pane is thus generally smaller than the outer glass pane in order to have sufficient space to fix the coupling element against the lateral edge of the internal glass pane. Thus, light emitted by the light source can be coupled through the edge of the light guide layer.

[0003] It is also known that the coupling element is provided onto the internal glass pane from the bottom so that the light is enabled to couple the internal glass pane. In such configuration, the lighting unit comprising the light source and the coupling element occupy a nonnegligible space under the internal glass pane and usage of such configuration limits the usable area of the glazing, i.e. , the available area that can be illuminated by the lighting unit.

[0004] It is also known that the coupling element can be various shapes and materials, one of the materials used for the coupling element is glass since the glass has the same refractive index as the internal glass pane so that the light passes through without loss or minimum loss. The coupling element is fixed onto the bottom of the internal glass pane by adhesives like optically clear adhesives which also have similar refractive indices like glass.

[0005] Although there are many advantages of the coupling element being glass, since the vehicle glazings are mostly curved, the coupling element needs to be bend.For the light coupling efficiency, the coupling element needs to have a minimum thickness which is most of the case higher than the thickness of the individual glass sheets of the glazing. Such thickness makes it harder bending of the coupling element by cold bending process in the range of the curvature of the glazing, thus hot bending process is needed. Additionally, the coupling element cannot be bent together with the glazing, it has to be bended separately. Therefore, even in the most controlled bending process, there are still some differences between the curvature values of the coupling element and the glass sheets due to tolerances in the production and such minor differences affects the coupling efficiency disruptively.

[0006] Even the coupling element is bent accordingly to the curvature of the glazing, external factors such as integration of roller blind to the glazing or else may create stress on the coupling element that the coupling element may break after installation. Furthermore, there may still be a gap between the coupling element and the glazing due to the 3D curvature of the glazing. The said gap reduces the coupling efficiency, i.e., less light from the light source is coupled to glazing. Besides, some light is diverged / escaped from the gap that causes non-uniform lighting which disturbs users.

[0007] Moreover, the coupling element may have at least one coating on one of its surface in order to increase the coupling efficiency. However, the coupling element cannot be bended after coating applied to its surface since such coatings absorbs or reflects heat that the bending process became uncontrollable. Additionally, some coatings are not compatible with high temperatures, i.e., may not resist to high temperatures. Applying a coating over a curved surface increases the cost of production.

[0008] Furthermore, fixing of the coupling element to the glazing is achieved by the adhesives. The issues mentioned above also causes problems on the glueing process and more control of the glueing needed because the excess glue needs to be cleaned when the glue flow out in between the coupling element and the glazing. Otherwise, the excess glue causes a tremendous reduction of the coupling efficiency.

[0009] It is also known from EP3463869, a lighting glazing comprising a glazing with holes and into which the light source is provided, although the coupling of light is improved with the collimation optics, such configuration with holes in the glazing makes the glazing difficult to produce.

[0010] It is also known from WO2021198262 to use a plastic coupling on the outer face (P4) of the roof. The coupling element described in WO’262 has a trapezoidal shape. Plastic material is often used for coupling element because it is easy to shape in the required shape and more particularly in complex shape in order to play the role of light guide. However, the coefficient of thermal expansion and the refractive index of plastic is different from the coefficient of thermal expansion and refractive index of the glass leading to reduced reliability of the assembly and a loss of light emitted by the light source through the glazing. Another issue with the plastic coupling is that the aging of the plastic material is beyond / faster than the glass, this one may lead to a decrease in the brightness or a color shift and eventually the plastic coupling element needs to be replaced.

[0011] It is also known from WO2023198638 to use a glass coupling element provided with a base surface and a light coupling region opposite to the base surface, and the coupling element is optically connected to the internal glass pane via its base surface, a top LED light source positioned onto the light coupling region to transmit light into the coupling element. Although a glass coupling element is disclosed, some embodiments requires plastic coupling element, since such a glass coupling element cannot be manufactured.

[0012] Additionally, more coupling elements are proposed by W02022030544, WO20231 60942 and WO2023198479 that the coupling element is trapezoid or wedge shaped or having tapered edge.

[0013] It is also known from WO2024017968 that the coupling element being glass and produced from the same float glass as the glazing, moreover the coupling element is shaped as strips in order to fit better onto the curved glazing. Moreover, said patent application discloses how light coupled into the internal glass pane, defines the total internal reflection condition, light coupling efficiency, how the coupling element is optically fixed onto the internal glass pane. The present invention provides an improved version of the said patent application.

[0014] Although there are many solutions in the prior art, there is still a need for such a coupling element that maximizes the amount of light coupled to internal glass pane, i.e., maximizes the coupling efficiency and yet minimizes the cost of production of such lighting glazing area by reducing number of required processes. Moreover, even thoseconditions satisfied, such a solution also needs to be less prone to alignment tolerances and provide ease of production.

[0015] None of the prior art above suggest a solution to the aforementioned issues of the glazing.SUMMARY OF THE INVENTION

[0016] It is an object of the present invention to provide a lighting laminated glazing and more particularly a laminated glazed roof more simple to produce and with good aesthetic to eliminate the aforementioned problems.

[0017] According to the invention, this object is achieved by a lighting vehicle glazing comprising (a) an external glass pane, (b) an internal glass pane acting as a light guide layer, (c) the first and the second glass panes being laminated together via at least a first interlayer, (d) a glass coupling element optically connected to the outer face of the internal glass pane and (e) a light source being positioned on the outer face of the internal glass pane facing the coupling element.

[0018] According to the present invention, the coupling element comprises a width defined proportionally with the radius of curvature of the glazing. Such configuration allows positioning the coupling element without a bending requirement and also with a minimized distance to the internal glass sheet, i.e., the gap is minimized, thereby enabling a higher coupling efficiency. A vehicle glazing is thus proposed in which the light emitted by the light source can be coupled into the light guide layer over a large area, specifically by means of the coupling element arranged on the outer surface of the glazing which facing the interior of the vehicle. Moreover the coupling element being flat enables the positioning / alignment of the coupling element less prone to tolerances.

[0019] In another aspect of the present invention, the lighting glazing may require less light source for the same lighting effect since the coupling element proposed by the present invention enables a higher light coupling efficiency. Moreover, the energy consumption of the lighting glazing may reduce since more light can be injected into the internal glass pane by the same light source. Furthermore, the coupling element of the present invention enables a more homogeneous / uniform lighting for the glazing.

[0020] In another aspect of the present invention, the glazing may be utilized moreefficiently, meaning that more usable space and more visible area for the passengers. Moreover, the coupling element of the present invention enables integration of other functional elements like roller blind and etc. and yet the visible area for passengers is not compromised. In addition, the coupling element of the present invention may enable more head room for the passengers, especially for the tall passengers.

[0021] In another aspect of the present invention, the coupling element of the present invention may enable ease of production. Moreover, the coupling element of the present invention enables less malfunctioning for the lighting glazing. In addition, the coupling element of the present invention enables affordable lighting glazing since the production times reduce significantly by eliminating bending of the coupling element.

[0022] In another aspect of the present invention, fixing the coupling element to the internal glass sheet by gluing process is facilitated by enabling more controlled process and also consumption of glue is significantly reduced. Moreover, with enabling more control of the gluing process, cleaning of the excess glue is also reduced.

[0023] According to one embodiment of the present invention, the coupling element is enabled to be coated with an anti-reflective coating or any relevant coating with a reduced cost since the coating can be applied over flat coupling element as the coupling element is not required to be bent.

[0024] According to another embodiment of the present invention, the distance between adjacent coupling elements are filled with an adhesive that the diverged light from the light source is enabled to be captured / coupled to coupling element such that the multiple flat narrow coupling elements acts as a longer coupling element conformed with the curvature of the glazing.

[0025] With the coupling element proposed by the present invention, glazings with lighting units / systems can be realized with a reduced cost by eliminating bending of the coupling element and further enabling the coating of the coupling element in its flat form and also the coupling element provides maximum light coupling efficiency possible.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The invention will now be described further, byway of examples, with reference to the accompanying drawings, wherein like reference numerals refer to like elementsin the various figures. These examples are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples. A better understanding of the present invention will be added upon reference to the following description in conjunction with the accompanying drawings.

[0027] Fig.1 is a view of a vehicle with glazing.

[0028] Fig.2 is a schematic top view of the lighting glazing according to one embodiment of the present invention.

[0029] Fig.3 is a schematic side view of the lighting glazing according to one embodiment of the present invention.

[0030] Fig.4 is an schematic top view of the lighting glazing according to one embodiment of the present invention and for illustration purposes the light source and the coupling element presented next to each other although they are positioned on top of each other.

[0031] The elements illustrated in the figures are numbered as follows:1 . Glazing11 . External glass pane12. Internal glass pane121. Edge13. Interlayer2. Lighting unit21 . Light source22. Coupling element w. width p. pitch d. distanceV. VehicleDETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0033] While some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0034] As used herein, spatial or directional terms, such as "inner", "outer", "above", "below", "top", "bottom", and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.

[0035] Moreover, all ranges disclosed herein are to be understood to be inclusive of the beginning and ending range values and to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1 , and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Further, as used herein, the terms "deposited over" or "provided over" mean deposited or provided on but not necessarily in surface contact with. For example, a coating "deposited over" a substrate does not preclude the presence of one or more other coating films of the same or different composition located between the deposited coating and the substrate.

[0036] Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated. In this document, "configured to (or set to)" may be interchangeably used in hardware and software with, for example, "appropriate to", "having a capability to", "changed to", "made to", "capableof", or "designed to" according to a situation. In any situation, an expression "device configured to do" may mean that the device "can do" together with another device or component.

[0037] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. When it is described that a constituent element (e.g., a first constituent element) is "(functionally or communicatively) coupled to" or is "connected to" another constituent element (e.g., a second constituent element), it should be understood that the constituent element may be directly connected to the another constituent element or may be connected to the another constituent element through another constituent element (e.g., a third constituent element).

[0038] In the following description, unless otherwise specified, expression “substantially” or “around” or “proximity” or “close to” preferably mean to within 10%, preferably to within 5% i.e. , in this context the terms should be understood as in the range of ± 10%, even more ± 5%. Tolerance may be selected depending on the nature of the intended applications.

[0039] In the following description, unless otherwise specified, expression “liquid adhesive”, “optical coupling material”, “optical resin”, “optical coupling adhesive”, “optical clear adhesive” and “liquid resin” are used interchangeably, further expression “functional film”, “film”, “electrically powered functional film” and “electrical functional film” are used interchangeably, further expression “flow”, “fluidic flow”, “liquid flow” and “liquid adhesive flow” are used interchangeably, further expression “external glass pane”, “first glass sheet” are used interchangeably, further expression “internal glass pane”, “second glass sheet” are used interchangeably, further expression “interlayer”, “bonding agent”, “PVB”, “PVB layer”, “plastic interlayer”, “thermoplastic interlayer” are used interchangeably, further expression “light source”, “LED” are used interchangeably, further expression “lighting vehicle glazing” and “lighting glazing” and “glazing” are used interchangeably, further expression “light”, “light beam”, “light ray(s)” are used interchangeably.

[0040] A lighting vehicle glazing (1 ) comprising an external glass pane (11 ) having an outer surface (P1 ) and an inner surface (P2) and an internal glass pane (12) having an inner surface (P3) and an outer surface (P4) and having at least one edge (121 ), the internal glass pane (12) acting as a light guide layer, and the external and the internal glass panes (11 , 12) being laminated together via at least an interlayer (13), the external and the internal glass panes (11 , 12) being curved and having a radius of curvature (r), a light source (21 ) provided in the vicinity of the edge (121 ) of the outer surface (P4) of the internal glass pane (12), at least one coupling element (22) provided in the vicinity of the light source (21 ), and optically bonded to the internal glass pane (12) on its outer surface (P4), that couples the light emitted from the light source (21 ) into the internal glass pane (12), the coupling element (22) having a width (w) parallel to the edge (121 ) of the internal glass pane (12). The light source (21 ) is provided under the coupling element (22) in the vertical direction, so the order follows as the light source (21 ), the coupling element (22), the internal glass pane (12), the interlayer (13) and the external glass pane (11 ) on top.

[0041] For simplicity, the numbering of the glass panes (11 , 12) in the continuation of the description refers to the numbering nomenclature conventionally used for glazing (1 ). Thus, the face of the laminated glass which is in contact with the environment external to the vehicle is known as being the face 1 (P1 ) and the surface in contact with the internal medium, that is to say the passenger compartment of the vehicle, is known as face 4 (P4).

[0042] In order to avoid any doubt, the terms “external” and “internal” refer to the orientation of the glazing during the installation as glazing in a vehicle. Anyhow, in the description below, these terms are used interchangeably, i.e. , the first glass sheet (11 ) may have face 1 and face 2 or face 3 and face 4 of the glazing, in the meantime the second glass sheet may (12) have face 3 and face 4 or face 1 and face 2, respectively which means first glass sheet (11 ) may be used as external side of the glazing (1 ) or the internal side of the glazing (1 ). Before going into the details of the coupling element (22), definitions for glazing (1 ), structure of the proposed glazing (1 ) will be explained herein.

[0043] According to the invention, the glass sheets (11 , 12) may be a glass of soda- lime-silica, aluminosilicate or borosilicate type, and the like, the composition of the glazing (1 ) is not crucial for the purpose of the present invention.

[0044] According to one example of the present invention, the Fig.2 shows a laminated automotive roof; the roof is intended to be fixed on the vehicle’s body. It is understood that the invention is not limited to a roof and in another preferred embodiment of the present invention, the laminated glazing (1 ) can be used in any glazing for a vehicle (V) and in another preferred embodiment of the present invention, the laminated glazing (1 ) can be used in outside or inside of automotive industry, i.e., anywhere where a laminated glazing (1 ) is needed.

[0045] The glazing (1 ) as shown in Fig.3 as an embodiment of the present invention comprises an external sheet of glass (11 ) having an external surface (P1 ) and an inner surface (P2), and an internal sheet of glass (12) having an inner surface (P3) and an outer surface (P4). Such glazing (1 ) is laminated. The first sheet of glass (11 ) of the glazing (1 ) is that sheet in contact with the exterior of the vehicle. The second sheet of glass (12) is that sheet in contact with the inner space of the vehicle. However, as explained above, the ordering can be changed and also the glazing (1 ) can be a triple glazing or any kind of glazing with at least two glass sheets (11 ,12).

[0046] For avoidance of doubt, the present invention is applicable for all means of transport such as automotive vehicle, vans, lorries, motorbikes, buses, trams, trains, airplanes, helicopters and the like... According to an embodiment of the present invention, the glazing may be a glazed roof, a sidelite, a backlite or a part of windshield of an automotive vehicle as shown in Fig.1 .

[0047] According to one embodiment of the present invention, the first and / or the second sheet of glass (11 , 12) are bent in a previous step before providing a coupling element (22) over at least one surface of the first or the second sheet of glass (11 , 12), i.e., before or after the lamination process and having a curvature radius (r). In a version of this embodiment, the curvature values of the first glass sheet (11 ) and the second glass sheet (12) are in line with each other, it has to be understood that the curvature values might not be the same. In another version of this embodiment, the external glass sheet (11 ) has a low curvature and the internal glass (12) is flat, this type of glazing (1 ) can also be counted as a curved glazing. The glass sheets (11 , 12) before the lamination may be totally or partially curved to reach the requested curvature of the final glazing (1 ) to correctly fit with the particular design of the glass support, as the shape required for the application. In another embodiment, the sizes of the two glass sheets (11 , 12) may differ from each other, in common practice, thefirst glass sheet (11 ) with P1 and P2 surfaces is bigger than the second glass sheet (12) with P3 and P4 surfaces. In any embodiment where the glazing (1 ) having a curvature which can be in one direction or in two directions. However, the sizes of the glazing (1 ) is not crucial for the present invention. For the sake of present invention, the curvature radius (r) of the internal glass sheet (12) means the curvature radius (r) of the glazing (1 ) after lamination process.

[0048] According to the present invention, the term “curved” is defined by the following criteria: “the curved laminated glazing has at least 50% of its total surface area having a minimum radius of curvature (R min) comprised between 50 and 15000 mm”. Thus, considering as example, a standard automotive laminated glazing, there are four main glass surfaces which are usually numbered 1 (outer surface) to 4 (inner surface) also called P1 , P2, P3 and P4 (from outer to inner of the vehicle). These glass surfaces have preferably before assembly very similar shapes. In the scope of the present invention, the outer surface P1 of the first glass sheet and the inner surface P4 of the second glass sheet have at least 50% of its surface area having a minimum radius of curvature comprised between 50 and 15000 mm after assembly. As reminder, at each point of a surface, an infinity of curvature radii can be evaluated (one for each direction). Among those radii, a minimum value “Rmin” and a maximum value “Rmax” value can be identified (as well as their associated directions). Of course, from one point to another on the surface, “Rmin” and “Rmax” (and their associated directions) will change. The minimum value “Rmin” should be understood as the curvature radius (r) in the context of the present invention. Measurement of the curvature radius of the glazing is a common practice in the field.

[0049] According the invention, the term "laminating" refers to a step of providing a layered structure in which one or more glass sheets (11 , 12) are separated by an interlayer (13) acting as a bonding agent extending across substantially the entire interface between the glass sheets (11 , 12). The glazing (1 ) is comprising at least one interlayer (13) as bonding layer for the substrate sheets (11 , 12). The interlayer (13) may be one of the conventional interlayers used in lamination processes, examples of the interlayer (13) are EVA, TPO, POE, PVB, TPU, Ionomers, optical clear adhesives (OCA) in liquid form or solid and etc. which are widely known and used in both automotive and architecture industry. The interlayer (13) can be clear or transparent or colored. For the sake of the invention, the material or other properties of theinterlayer (13) is not utmost important.

[0050] The light source (21 ) is provided in the vicinity of the outer surface (P4) of the internal glass pane (12), more specifically the light source (21 ) is being positioned on the outer face (P4) of the internal glass pane (12) facing the coupling element (22), such positioning of the light source (21 ) is illustrated in the figures 3 and 4, in other words, the light source (21 ) is provided under the coupling element (22) in the vertical direction that the lighting glazing (1 ) of the present invention is considered bottom-lit lighting glazing. The light source (21 ) can be designed in particular as a high- performance LED module, is an LED bar or an LED strip with a large number of LEDs, which emit their light directly into the coupling element (22) or a lightguide that can emit light from its sides at predetermined intervals. In another embodiment, the light source (21 ) is optical fibers to transmit light, a waveguide combined with LEDs or laser diodes. The light source (21 ) may also comprise a lens (not shown) to collimate and / or focus the light emitted onto the coupling element (22), in the preferred version the light beam hitting on the coupling element (22) is collimated. For the sake of the invention, the properties of the light source (21 ) is not utmost important.

[0051] The coupling element (22) is provided in the vicinity of the light source (21 ), and optically bonded to the internal glass pane (12) on its outer surface (P4), that couples the light emitted from the light source (21 ) into the internal glass pane (12). The coupling element (22) having a width (w) parallel to the edge (121 ) of the internal glass sheet (12) and optically connected to the outer face (P4) of the internal glass pane (12) and is made of glass.

[0052] According to the present invention, the coupling element (22) may be arranged onto the outer face (P4) of the internal glass pane (12) in case of glazing is a laminated glazing or onto the inner face (P2) of the glazing in case of the glazing is a toughened safety glass and tempered safety glass, therefore the present invention is not limited to laminated glazings.

[0053] According to the present invention, the coupling element (22) can be attached directly to the outer face (P4) of the internal glass pane (12) via an optical adhesive, such optical adhesives are widely known and the term adhesive should be understood in its broadest scope that the adhesive may be in liquid or solid form. The coupling element (22) is preferably coupled to the light source (21 ). Thus, the coupling element(22) is provided in the vicinity of the light source (21 ) and is preferably in contact with it (direct contact or not) to be able to couple the light coming out from the light source (21 ) to the coupling element (22). Moreover, the light source (21 ) and the coupling element (22) form a lighting unit (2), the lighting unit (2) may comprise other elements such as the optical adhesive.

[0054] As shown in figures 2 to 4, the axis are defined as follows. Z-axis is the vertical axis that at any given point on the surface of the glazing (1 ), the z-axis is perpendicular to the glazing surface. X-axis is defined as the parallel axis to the edge (121 ) of the glazing (1 ) where the lighting unit (2) extends. Y-axis is defined as the perpendicular axis to the x-axis and z-axis. Therefore, the width (w) of the coupling element (22) should be understood as the length of the coupling element (22) in the x-axis, and the pitch (p) of the light source (21 ) should be understood as the distance inbetween two adjacent light source (21 ) in the x-axis and the distance (d) inbetween two adjacent coupling element (22) are also defined in the x-axis.

[0055] According to the present invention, the light emitted by the light source (21 ) is pointing towards the coupling element (22) and the light propagates into the coupling element (22) as the incident angle is almost zero degree, i.e., light beam is substantially perpendicular to the edge of the coupling element (22), the incident angle is defined as the angle between the incoming light ray and the normal of the surface light ray directed. Since the coupling element (22) is made of glass, the light directed towards the internal glass pane (12) propagates into the internal glass pane (12) almost without changing its direction. Then the light reflects from the inner surface (P3) of the internal glass pane (12) satisfying total internal reflection condition thanks to the structural design of the coupling element (22). Afterwards, the light coupled into the internal glass pane (12) illuminates the interior of the vehicle, in some embodiments the internal glass pane (12) may have a pattern (not shown) on its P4 or P3 surface that the users perceive an illuminated pattern, in other embodiments, the illumination can be achieved with a film layer laminated inside the glass panes, especially film layer facing the P3 surface of the internal glass pane. How the illumination of the glazing (1 ) works is very well known and the present invention is about the improvements related to the coupling element (22).

[0056] The lighting vehicle glazing (1 ) of the present invention comprises the coupling element (22) having a width (w) parallel to the edge (121 ) of the internal glass pane(12) and the width (w) of the coupling element (22) is proportional to the radius of the curvature (r) of the internal glass sheet (12). The light source (21 ) is provided along the edge (121 ) of the internal glass sheet (12). The coupling element (22) is also aligned with the light source (21 ), i.e., provided along the edge (121 ) of the internal glass sheet (12). The radius of the curvature (r) should be understood as in the same axis / direction with the width (w) of the coupling element (22), namely the x-axis in the figures, as the curvature radius may also be defined in other directions since the most vehicle glazings have 3D shapes. The width (w) of the coupling element (22) is defined proportional to the radius of curvature (r) of the internal glass sheet (12), therefore such arrangement allows the use of flat coupling elements (22) thus the coupling element (22) need not to be bent and multiple flat coupling elements (22) are provided along the edge of the edge (121 ) of the internal glass sheet (12) inline with the light source (21 ). As described in the introduction, there is a gap between the coupling element (22) and the internal glass sheet (12) and the said gap still exists even the coupling element (22) is bent and the distance between the coupling element (22) and the internal glass sheet (12) is exponentially proportional with the width (w) of the coupling element (22). The gap should be understood as the maximum distance value inbetween the coupling element (22) and the internal glass sheet (12) in the z-axis, namely the distance between a point substantially in the middle of the coupling element (22) in the x-axis and the internal glass sheet (12) as the cross-section of the internal glass sheet (12) defines an arc and the coupling element (22) defines a line. Defining the width of the coupling element (22) proportional to the radius of curvature (r), therefore allows the said gap distance to be minimized. Furthermore, with the present invention, light escaping before coupling to the internal glass sheet (12) is prevented and light coupling efficiency is improved. Moreover, since the requirement for bending of the coupling element (22) is now deceased, production of the glazing (1 ) is simplified and the cost of production is tremendously reduced due to removal of process steps and shortening the time of production.

[0057] The width (w) of the coupling element (22) being proportional to the radius of the curvature (r) of the internal glass sheet (12) is explained with some examples. In the case of the glazing (1 ) does not have a curvature, i.e., being flat, then the width (w) of the coupling element (22) may be chosen as long as the edge (121 ) of the internal glass sheet (12). As the curvature of the glazing (1 ) increases, i.e., the radiusof the curvature (r) of the glazing (1 ) decreases, then the width (w) of the coupling element decreases in order to keep the gap minimized. In the case of a highly curved glazing (1 ), narrower coupling elements (22) may be deployed and thanks to the invention, the coupling elements (22) need not to be bent. The proportionality of the said values can be a linear correlation or an exponential correlation. In one of the preferred embodiments of the present invention, the width (w) of the coupling element (22) is in the range of 0.5 to 50 cm, and preferably 0.5 to 20 cm, and more preferably 0.5 to 5 cm for a glazing (1 ) having a radius of curvature (r) in the range of 50 to 15000 mm.

[0058] In one of the preferred embodiments of the present invention, the proportionality of the width (w) of the coupling element (22) and the radius of the curvature (r) of the glazing can be seen from the following example. For a given radius of curvature (r) value of 5000 mm, a coupling element (22) with a width (w) of 6 cm will result a maximum gap of 0.09 mm inbetween the coupling element (22) and the glazing (1 ) and in another example, for a given radius of curvature (r) value of 2800 mm, a coupling element (22) with a width (w) of 4 cm will result a maximum gap of 0.07 mm inbetween the coupling element (22) and the glazing (1 ). The inventors of the present invention aims to keep the maximum gap value below 0.1 mm in order to achieve the maximum possible light coupling, thus the proportionality in the preferred embodiment may also be understood as to keeping the maximum gap value below 0.1 mm, i.e. , the width (w) of the coupling element (22) may be determined proportional with the radius of curvature (r) that the maximum gap is kept below 0.1 mm or even a lower value. The given values should be understood within the measurement tolerances.

[0059] In one embodiment of the present invention, the lighting vehicle glazing (1 ) comprises the light source (21 ) having multiple individual LEDs positioned parallel to the edge (121 ) of the internal glass sheet (12) and having a distance of pitch (p) in between adjacent LEDs, and the minimum width (221 ) of the coupling element (22) is the distance of pitch (p). As defined previously, the light source (21 ) may be in different forms, in this embodiment, the light source (21 ) has multiple individual LEDs arranged next to each other along the edge (121 ) of the internal glass sheet (12). The minimum width (w) of the coupling element (22) being the pitch distance (p) of the light source (21 ) enables each coupling element (22) to serve at least one LED. Therefore, defining the minimum width (w) as such allows light coupling efficiency not to decrease from athreshold value although a narrower coupling element (22) may allow minimization of the gap between the coupling element (22) and the internal glass sheet (12).

[0060] In another embodiment of the present invention, the coupling element (22) is centered with one of the LEDs, namely, the center of the coupling element in the x- axis and the center of the individual LED in the x-axis are aligned. As the light from the light source (21 ) diverges, aligning the coupling element (22) centered with one of the LEDs allows diverged light to be able couple to coupling element (22) and therefore the internal glass sheet (12). Especially in the case of the light source (21 ) having odd numbered individual LEDs, the center of the coupling element (22) is aligned with the center of the LED in the middle.

[0061] In another embodiment of the present invention, the width (221 ) of the coupling element (22) is multiples of the distance of pitch (p). Similarly to the above embodiment, in the case of the light source (21 ) having multiple individual LEDs, providing the width (w) of the coupling element (22) as multiples of pitch (p) of LEDs allows centering of the coupling element (22) with at least one of the LEDs. As the width (w) of the coupling element (22) defined inline with the pitch distance of the light source (21 ), the coupling efficiency is enabled to be satisfied a predetermined threshold value.

[0062] In another embodiment of the present invention, there is a distance (d) between the adjacent coupling elements (22) and the said distance (d) is inversely proportional with the radius of curvature (r) of the internal glass sheet (12). As the glazing has a radius of curvature (r) and the coupling element (22) is provided as flat shaped, there has to be a distance between the adjacent coupling elements (22) in order for the multiple coupling elements (22) to follow the curvature of the glazing (1 ) and such distance is defined inversely proportional with the radius of curvature (r) of the glazing (1 ), i.e. , the more flatter the glazing, the less distance in-between the adjacent coupling elements (22).

[0063] In another embodiment of the present invention, the minimum distance (d) between adjacent coupling elements (22) is at least 0.1 mm, preferably at least 0.3 mm, and more preferably 0.5 mm. The minimum distance is correlated with the thickness of the coupling element (22). In order to conform the curvature of the glazing, the adjacent coupling elements (22) are provided with a distance of at least 0.1 mmthat the edges of adjacent coupling elements (22) will not touch each other.

[0064] In another embodiment of the present invention, the distance (d) between adjacent coupling elements (22) is filled with an adhesive. Providing adhesives to the side edges of the coupling element (22) improves the stability and the fixation of the coupling elements (22). The adhesive may be in liquid or in solid form.

[0065] In another embodiment of the present invention, the adhesive having an index of refraction substantially same with the index of refraction of the coupling element (22). Therefore, the diverged light is enabled to couple to the next coupling element (22) and continuity of the coupling elements (22) are achieved therefore the coupling efficiency is improved. One example for such an adhesive is the optical clear adhesives (OCA) with an index of refraction similar with the glass.

[0066] In another embodiment of the present invention, the surface of the coupling element (22) facing the light source (21 ) is coated with an anti-reflective coating. As the coupling element (22) of the present invention does not need to be bent and enabled to be flat shaped, any coating can be applied over the surfaces of the coupling element (22) by the conventional coating processes for flat glass sheets.

[0067] In another embodiment of the present invention, the lighting vehicle glazing (1 ) of the present invention is a vehicle roof glazing.

[0068] In another embodiment of the present invention, the lighting glazing (1 ) may comprise a black enamel layer (not shown) provided on the periphery of the glazing (1 ). Such black enamel layer is also known as black band in the automotive industry and it is very well known.

[0069] In another embodiment of the present invention, the lighting glazing (1 ) may comprise a coating (not shown) for thermal management, preferably a low emissivity coating provided on P4 surface of the glazing (1 ) or a metallic coating provided on different surfaces (P1 , P2, P3, P4) of the glazing (1 ), provided the area where the coupling element (22) is fixed onto glazing (1 ) surface free of coating. Such thermal management coatings are effective to keep the internal heat inside the vehicle and / or keeping the outside heat away from the vehicle.

[0070] In another embodiment of the present invention, the lighting glazing (1 ) also comprises photovoltaic solar cells (not shown) laminated inbetween the external (11 ) and internal glass panes (12). The photovoltaic solar cells are producing electricityfrom the sun.

[0071] In another embodiment of the present invention, the lighting glazing (1 ) also comprises a functional film (not shown) laminated inbetween the external (11 ) and internal glass panes (12). The functional film may comprise liquid crystals and perform dimming function or else.

[0072] With this invention, the lighting glazings (1 ) can be realized more affordably and providing more room for the passengers and also the manufacturer to integrate elements like roller blind without compromising the aesthetics of the vehicle since the lighting glazing (1 ) is already a bottom-lit lighting glazing occupying narrow space and also the coupling element (22) of the present invention enables it to be less prone to stress. Moreover with the coupling element (22) of the present invention, the production costs for the lighting glazing (1 ) are reduced significantly that allows a lighting glazing for affordable vehicles and furthermore, the running costs for the lighting glazing (1 ) are reduced significantly since more light can be coupled into the internal glass pane (12) than prior art examples.

[0073] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. The invention is not limited to the disclosed embodiments.

Claims

Claims1 . A lighting vehicle glazing (1 ) comprising an external glass pane (11 ) having an outer surface (P1 ) and an inner surface (P2) and an internal glass pane (12) having an inner surface (P3) and an outer surface (P4) and having at least one edge (121 ), acting as a light guide layer, and the external and the internal glass panes (11 , 12) being laminated together via at least an interlayer (13), the external and the internal glass panes (11 , 12) being curved and having a radius of curvature (r), a light source (21 ) provided in the vicinity of the edge (121 ) of the outer surface (P4) of the internal glass pane (12), at least one coupling element (22) provided in the vicinity of the light source (21 ), and optically bonded to the internal glass pane (12) on its outer surface (P4), that couples the light emitted from the light source (21 ) into the internal glass pane (12), the coupling element (22) having a width (w) parallel to the edge (121 ) of the internal glass pane (12); characterized in that the width (w) of the coupling element (22) is proportional to the radius of the curvature (r) of the internal glass sheet (12).

2. A lighting vehicle glazing (1 ) according to claim 1 , characterized in that the light source (21 ) having multiple individual LEDs positioned parallel to the edge (121 ) of the internal glass sheet (12) and having a distance of pitch (p) in between adjacent LEDs, and the minimum width (221 ) of the coupling element (22) is the distance of pitch (p).

3. A lighting vehicle glazing (1 ) according to claim 2, characterized in that the coupling element (22) is centered with one of the LEDs.

4. A lighting vehicle glazing (1 ) according to claim 2 or 3, characterized in that the width (221 ) of the coupling element (22) is multiples of the distance of pitch (P).

5. A lighting vehicle glazing (1 ) according to anyone of preceding claims, characterized in that the distance (d) between adjacent coupling elements (22) is inversely proportional with the radius of curvature (r) of the internal glass sheet (12).

6. A lighting vehicle glazing (1) according to anyone of preceding claims, characterized in that the minimum distance (d) between adjacent coupling elements (22) is at least 0.1 mm.

7. A lighting vehicle glazing (1) according to anyone of preceding claims, characterized in that the distance between adjacent coupling elements (22) is filled with an adhesive.

8. A lighting vehicle glazing (1 ) according to claim 7, characterized in that the adhesive having an index of refraction substantially same with the index of refraction of the coupling element (22).

9. A lighting vehicle glazing (1) according to anyone of preceding claims, characterized in that the surface of the coupling element (22) facing the light source (21 ) is coated with an anti-reflective coating.

10. A vehicle roof glazing comprising the lighting vehicle glazing (1 ) according to any of the preceding claims.

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