Vehicle surface light guide

Abstract

The invention relates to a surface light guide for a vehicle comprising light injection elements (10) and a light guide mat (11), said light injection elements (10) being configured to be coupled with at least one light source (20). According to the invention, the light injection elements (10) comprise first ends (10.1) and second ends (10.2) and are grouped at their first ends (10.1) into a beam so as to form a light mixing zone (13) intended to be positioned opposite said at least one light source (20). Figure for the abstract: Figure 1

Description

Title of the invention: Surface light guide for vehicle

[0001] The present invention relates to a surface light guide for a vehicle. It finds a particular but not limited application in motor vehicles.

[0002] A surface light guide known to those skilled in the art comprises light injection elements and a light guide sheet, said light injection elements being configured to be coupled with at least one light source. The light injection elements are folded to form a stack. The stack has an input surface configured to receive light rays emitted by the light source.

[0003] A disadvantage of this state of the art is that there is an inhomogeneous distribution of light in the different light injection elements. In particular, given that the light source arranged in front of the stack emits light in a cone, also called a light distribution cone, the light injection elements located at the upper and lower ends of the stack receive less light than those located in the middle of the stack. Consequently, the light is transmitted outwards by the light guide sheet (which is adjacent to the light injection elements) in an inhomogeneous manner.

[0004] In this context, the present invention aims to propose a light guide which makes it possible to solve the mentioned drawback.

[0005] For this purpose, the invention proposes a surface light guide for a vehicle comprising light injection elements and a light guide sheet, said light injection elements being configured to be coupled with at least one light source. According to the invention, said light injection elements comprise first ends and second ends and are grouped at their first ends in a bundle so as to form a light mixing zone intended to be arranged opposite said at least one light source.

[0006] Thus, as will be seen in detail later, the grouping of the first ends of the injection elements in the form of a beam allows all of the first ends of the injection elements to be well positioned opposite the light source and allows each light injection element to thus receive substantially the same quantity of light from the mixing zone. In other words, the mixing zone makes it possible to obtain homogeneous light which is injected by the light injection elements up to the light guide sheet.

[0007] According to non-limiting embodiments, said light guide may further comprise one or more additional characteristics taken alone or in all the technically possible combinations, among the following.

[0008] According to a non-limiting embodiment, said first ends of said light injection elements are embedded in a resin. In this exemplary embodiment, the first ends of the light injection elements are distributed randomly in the resin. This is a simple solution to implement.

[0009] According to a non-limiting embodiment, said first ends of said light injection elements are grouped by fusion. This makes it possible to have a good filling factor.

[0010] According to a non-limiting embodiment, said light injection elements have a width of between 0.1 mm (millimeters) and 5 mm. This makes it possible to obtain a light mixing zone which has reduced dimensions.

[0011] According to a non-limiting embodiment, said light mixing zone has a cylindrical or rectangular or hexagonal section. The cylindrical section is advantageous for having good coupling efficiency. The hexagonal section is advantageous when a multi-source RGB diode is used which comprises three R, G and B emitters. The positioning of these three emitters is facilitated by the hexagonal shape and allows good mixing of the different R, G and B lights to obtain white light. The rectangular section is an easy shape to shape, in particular by melting.

[0012] According to a non-limiting embodiment, said light guide sheet extends along a first direction and along a second direction and said light injection elements are adjacent to said light guide sheet by their second ends and extend along the first direction.

[0013] According to a non-limiting embodiment, said light injection elements are of rectangular section. They are easily cut from a large sheet.

[0014] According to a non-limiting embodiment, said at least one light source is a semiconductor light source.

[0015] According to a non-limiting embodiment, said semiconductor light source is a light-emitting diode or a laser diode.

[0016] According to a non-limiting embodiment, said light guide sheet comprises at least one light emission zone comprising all or part of a light pattern.

[0017] According to a non-limiting embodiment, the light injection elements and the light guide sheet are manufactured from a large sheet which is sheared on one end to separate the different light injection elements in a first direction y and thus form the different light injection elements 10 and the light guide sheet.

[0018] Also provided is a vehicle lighting device, said device light comprising at least one light guide according to any one of the preceding characteristics and at least one light source arranged opposite said light mixing zone.

[0019] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures:

[0020] [Fig-1] is a schematic illustration of a surface light guide according to a first non-limiting embodiment of the invention, the light guide comprising a light guide sheet and light injection elements comprising first and second ends which are grouped at their first ends so as to form a light mixing zone, the first ends being embedded in a resin,

[0021] [Fig.2] is an enlarged view of a section of the light mixing area of ​​[Fig.2],

[0022] [Fig.3] is a schematic illustration of a surface light guide according to a second non-limiting embodiment of the invention, the light guide comprising a light guide sheet and light injection elements comprising first and second ends which are grouped at their first ends so as to form a light mixing zone, the first ends being merged,

[0023] [Fig.4] is an enlarged view of a section of the light mixing area of ​​[Fig.3],

[0024] [Fig.5] is a schematic illustration of the light guide of [Fig.l] or [Fig.3] in which the first ends of the light injection elements are not grouped.

[0025] Elements that are identical, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references.

[0026] The light guide 1 according to the invention is described with reference to Figures 1 to 5. In a non-limiting embodiment, the light guide 1 is a light guide for a vehicle. In a non-limiting embodiment, the vehicle (not shown) is a motor vehicle. By motor vehicle is meant any type of motorized vehicle. This embodiment is taken as a non-limiting example in the remainder of the description. In the remainder of the description, the vehicle is thus otherwise called a motor vehicle. In a non-limiting variant embodiment, the vehicle is a thermal vehicle or an electric vehicle.

[0027] The light guide 1 is surface-mounted. Thus, it can be adapted to any type of flat or curved surface. A surface-mounted light guide is understood to mean an optical guiding element one of whose dimensions is much smaller than the other two dimensions in space, for example smaller by one or more orders of magnitude. Here, the thickness of the light guide 1 is much less than its length L and its width La (illustrated in [Fig.5]). In a non-limiting embodiment, the light guide 1 has a thickness of between 10 and 1000 μm (micrometers). In a non-limiting alternative embodiment, the thickness is between 50 and 1000 μm. In a non-limiting example, the thickness is 50 μm. The light guide 1 is thus very thin.

[0028] In a non-limiting embodiment, said light guide 1 is flexible. By flexible, it is understood that the light guide 1 is adapted to be curved without being damaged or breaking. It can thus be arranged in a lighting device 2 and follow curves linked to a particular style of said lighting device 2. The lighting device 2 may comprise a mask. In non-limiting embodiments, the lighting device 2 is a lighting and / or signaling device, or all or part of a front face or a rear face of the motor vehicle. A part of the front face may be the grille or the bumper in non-limiting examples. In non-limiting embodiments, the lighting and / or signaling device is a headlight or a rear light.

[0029] Thanks to the fact that it is surface-mounted and flexible, the light guide 1 is configured to be placed on the front face of the motor vehicle or in a headlight or rear light of the motor vehicle, for example behind an outlet window of the headlight or rear light or in front of a mask of the headlight or rear light. In a non-limiting embodiment, the light guide 1 is made of polycarbonate (PC), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU), or polyethylene terephthalate (PET). Such materials make it possible to produce a flexible light guide 1.

[0030] The light guide 1 comprises: - a plurality of light injection elements 10, and - a light guide sheet 11.

[0031] The light injection elements 10 are configured to be coupled with at least one light source 20. Said at least one light source 20 is part of the lighting device 2. It is arranged opposite the light mixing zone 13 described later.

[0032] In a non-limiting embodiment, a single light source 20 is used. This non-limiting embodiment is taken as a non-limiting example in the remainder of the description. In a non-limiting embodiment, the light source 20 is a semiconductor light source. In a non-limiting embodiment, the semiconductor light source is part of a light-emitting diode or a laser diode. By light-emitting diode, we mean any type of light-emitting diode, whether in non-limiting examples LEDs (Light Emitting Diodes), OLEDs (Organic LEDs), AMOLEDs ("Active-Matrix-Organic LED" in English), or FOLED ("Flexible OLED" in English). In a non-limiting embodiment, the light source 20 is composed of several distinct emitters. In a non-limiting example, the light-emitting diode is an RGB diode. The RGB light source is said to be multi-source with three RG and B emitters which have different sizes and with different geometric arrangements.

[0033] The light source 20 is configured to emit light rays R (illustrated in [Fig.l] and 3) which will propagate by total reflection in the light injection elements 10 so as to bring light to the light guide sheet 11 which is adjacent to the light injection elements 10 and which will thus illuminate the light emission zone(s) 110 (described later) of the light guide sheet 11.

[0034] A light injection element 10 is configured to receive the light rays R emitted by the light source 20 which propagate and are reflected in their entirety in said light injection element 10. The light injection element 10 has a rectangular or square cross-section. The set of light injection elements 10 can be compared to an optical fiber in terms of the geometric shape.

[0035] [Fig. 5] illustrates the light injection elements 10 when they are not yet grouped. The light injection elements 10 have a length Lg', a width La' and a thickness (not illustrated). Their thickness is that of the thickness of the light guide 1. The sum of the widths La' of the light injection elements 10 is equal to the width La of the light guide 1. In a non-limiting embodiment, the light injection elements 10 have a width La' of between 0.1 and 5 mm. In a non-limiting alternative embodiment, the width La' is between 0.5 and 2 mm. In a non-limiting alternative embodiment, the width La' is between 1 mm and 2 mm. It will be noted that the smaller their width La', the easier it will be to group the light injection elements 10 in the light mixing zone 13 described later.However, if the width La' is too small, it will be difficult to cut the light injection elements 10 cleanly and not damage them. In a non-limiting embodiment, the light injection elements 10 have a thickness of approximately 50 μm. In a non-limiting embodiment, the light injection elements 10 have a length Lg' of between 200 and 500 millimeters (mm).

[0036] The light injection elements 10 comprise a first end 10.1 and a second end 10.2, one of which 10.2 is directly adjacent and attached to the light guide sheet 11 and the other 10.1 is configured to face the light source 20. The light injection elements 10 are thus adjacent to said light guide sheet 11 by their second ends 10.2.

[0037] The light rays R emitted by the light source 20 thus enter through the first end 10.1 of the light injection elements 10 and are transmitted to their second ends 10.2 then to the light guide sheet 11. It will be noted that during the manufacturing process of the light guide 1, the light injection elements 10 and the light guide sheet 11 are manufactured from a large sheet which is sheared on one end to separate the different light injection elements 10 in a first direction y and thus form the different light injection elements 10 and the light guide sheet 11. The light injection elements 10 are thus obtained by shearing the large sheet. Thus, the light injection elements 10 remain attached to the light guide sheet 11 on one of their ends, here the second end 10.2.Such light injection elements 10 being known to those skilled in the art, they are not described in further detail.

[0038] As illustrated in Figures 1, 3 and 5, in a non-limiting embodiment, the light guide sheet 11 extends in its length Lg along a first direction y and in its width La along a second direction z substantially perpendicular to the first direction y and to a third direction x. It will be noted that the width La and the length Lg may be equal. The width La is that of the light guide 1. It will be noted that the third direction x is substantially perpendicular to the front face or the rear face of the vehicle when the light guide 1 is mounted on the front face or the rear face of the vehicle. Specifically, the third direction x is perpendicular to the surface on which the light guide 1 is mounted. In a non-limiting embodiment, said surface is part of the front face or the rear face of the vehicle.In a configuration where this surface is curved, the third direction x is perpendicular to the tangent of the curvature of this surface.

[0039] The light guide sheet 11 comprises at least one light emission zone 110 comprising all or part of a light pattern 111. In a non-limiting embodiment, the light guide sheet 11 comprises a plurality of light emission zones 110. The light emission zone(s) 110 comprise a light pattern 111 visible to an external observer. The light pattern 111 is formed by a plurality of microstructures for decoupling the light from the light guide 1. In a non-limiting example, the light pattern 111 may be a logo. Thus, in this case, an illuminated logo can be obtained. In the non-limiting example illustrated in Figures 1 and 3, the light pattern 111 is arranged in a single light emission zone 110 and has a rectangular shape.

[0040] The light guide 1 being surface-mounted, flexible and transparent, the light guide sheet 11 is consequently surface-mounted, flexible and transparent. The guide sheet light guide sheet 11 being flexible, it can be flat or curved depending on the position in which it is placed and the mechanical constraints applied to it. In particular, it adapts to the front face or to the exit window or to a mask of a headlight or a rear light of the motor vehicle or of a body panel.

[0041] The light guide sheet 11 further comprises at least one light mixing region 112. The light which emerges from the light injection elements 10 will be mixed in the light mixing region 112.

[0042] A light emission zone 110 is a zone through which the light generated by the light rays R of the light source 20 emerges from the light guide sheet 11. In particular, it emerges in a light emission direction which is substantially parallel to the third direction x. In the non-limiting examples of the front face or the exit window or the mask of the headlight or the rear light or a body panel, it emerges at least in part towards the outside of the motor vehicle.

[0043] The light injection elements 10 extend mainly along the first direction y, in a non-limiting embodiment. The dimension measured along this first direction y is thus considered to be the length Lg' (illustrated in [Fig.5]) of the light injection element 10.

[0044] As illustrated in [Fig.5], the length L of the light guide 1 is the sum of the length Lg of the light guide sheet 11 and the length Lg' of the light injection elements 10.

[0045] As illustrated in Figures 1 and 3, the light injection elements 10 are grouped at their first ends 10.1 in a bundle so as to form a light mixing zone 13 intended to be arranged opposite said light source 20. The light rays R emitted by said at least one light source 2 mix in the light mixing zone 13. The light injection elements 10 are grouped so as to form an integral assembly, also called a bundle of light injection elements.

[0046] In non-limiting embodiments, the light mixing zone 13 has a cylindrical or rectangular or hexagonal section. In the non-limiting example illustrated in Figures 2 and 4, the light mixing zone 13 has a cylindrical section. In a non-limiting example, the cylindrical section has a diameter of between 1 and 10 mm. This dimension depends on the number of light injection elements 10 and the dimension of the light source 20. As can be seen, the light mixing zone 13 has a diameter significantly smaller than the width La of the light guide 1 which is also the sum of the widths La' of all the light injection elements 10 placed side by side as illustrated in [Fig.5].

[0047] As can be seen in Figures 1 and 3, the light mixing zone 13 is in the form of a beam. This shape is a compact shape. The light rays R emitted by the light source 20 enter through this beam. The grouping of the first ends 10.1 of the light injection elements 10 into a beam makes it possible to have an entry surface for the light which is reduced compared to the prior art. The entry surface is thus adapted to the dimensions of the light source 20. The light rays R emitted by the light source 20 will enter through this reduced entry surface before mixing in the mixing zone 13. At the exit from the light mixing zone 13, all the light injection elements 10 will receive substantially the same quantity of light.

[0048] In a first non-limiting embodiment illustrated in Figures 1 and 2, the first ends 10.1 of the light injection elements 10 are embedded in the resin C. The first ends 10.1 are distributed randomly in the resin C.

[0049] In [Fig.2] in section, we can see the different first ends 10.1 of the different light injection elements 10 of the light guide 1 which form the light mixing zone 13 and which are thus embedded in the resin C. The resin C makes it possible to mechanically fix the first ends 10.1 and makes it possible to pass the light from one first end 10.1 to another first end 10.1. The light will mix in the light mixing zone 13 formed by these first ends 10.1 thanks to the resin C.

[0050] As illustrated in the sectional view of [Fig.2], the first ends 10.1 of the light injection elements 10 which are grouped to form the light mixing zone 13 will take position naturally in the resin C so as to maximize the filling in the mixing zone 13. Thanks to this compact configuration, the light mixing zone 13 has a filling factor called in English "fill factor" which is not 100%. The filling factor is a filling rate of the useful surface on the total surface. It will be noted that the lower the filling factor, the more light escapes at the exit of the light mixing zone 13 when the light injection elements 10 regain their independence, the exit of the light mixing zone 13 being the end of the mixing zone 13 opposite the other end which is the light entry zone.Conversely, the closer the fill factor is to 100%, the less light loss there is.

[0051] In a second non-limiting embodiment illustrated in Figures 3 and 4, the first ends 10.1 of the light injection elements 10 are grouped by fusion. Thus, they are fused together. As illustrated in [Fig.4] in section, as the first ends 10.1 have been fused to form the area of light mixing zone 13, they are no longer distinguished from each other. They now form only a single first end 10.1, called the first global end 10.1. All the light injection elements 10 will thus have the same first global end 10.1 and will thus receive the same quantity of light. The light will mix in the light mixing zone 13 formed by this first global end 10.1 which is the fusion of all the first ends 10.1 of the light injection elements 10. In a non-limiting embodiment, the fusion is carried out by heating or by ultrasound. After fusion, it is possible to shape the light mixing zone 13 with a cylindrical, hexagonal or rectangular section, or any other desired shape. The fusion makes it possible to have a filling factor of 100% of the light mixing zone 13. Thus, good efficiency is obtained. There is no longer any loss of light.In a non-limiting embodiment, the light mixing zone 13 is surrounded by a holding element C' as illustrated in [Fig.4]. The holding element C' is a holding sheath or a metal ferrule.

[0052] Of course, the description of the invention is not limited to the embodiments described above and to the field described above.

[0053] Thus, in the vehicle field, in another non-limiting embodiment, it can be applied to an interior element of the vehicle such as the dashboard for lighting a light pattern. The pattern is then seen by an observer who is located inside the vehicle in this case.

[0054] Thus, the invention can be applied to any application other than the vehicle application, such as an application in the field of aviation, railways, for example for lighting a pattern in a cockpit of an airplane or a cabin of a train. It can also be applied to applications in the field of advertising on billboards or on storefronts or in buildings. It can also be applied to applications in the field of toys, decoration, or multimedia.

[0055] Thus, the light device 2 can comprise more than one light source 20. It can comprise three RGB light sources which are each arranged opposite the light mixing zone 13, so as to form white light when the light rays R emitted by the three RGB light sources mix in the light mixing zone 13.

[0056] Thus, the invention described presents in particular the following advantages: - it allows for a homogeneous distribution of light in the light injection elements 10 of the light guide 1, - grouping part of the ends of the light injection elements into a beam makes it possible to modify the shape of the light entry surface in order to adapt to the light source 20 and allows any geometry of light source 20 to be used. Thus, it is not necessary to have a light source 20 of the same dimension as the light input surface.

Claims

Claims

1. Surface light guide (1) for a vehicle comprising light injection elements (10) and a light guide sheet (11), said light injection elements (10) being configured to be coupled with at least one light source (20), characterized in that said light injection elements (10) comprise first ends (10.1) and second ends (10.2), and are grouped at their first ends (10.1) in a bundle so as to form a light mixing zone (13) intended to be arranged opposite said at least one light source (20).

2. A light guide (1) according to claim 1, wherein said first ends (10.1) of said light injection members (10) are embedded in a resin (C).

3. A light guide (1) according to claim 1, wherein said first ends (10.1) of said light injecting elements (10) are fused together.

4. A light guide (1) according to any preceding claim, wherein said light injecting elements (10) have a width of between 0.1 and 5mm.

5. Light guide (1) according to any one of the preceding claims, wherein said light mixing zone (13) has a cylindrical or rectangular or hexagonal section.

6. A light guide (1) according to any preceding claim, wherein said light guide sheet (11) extends along a first direction (y) and along a second direction (z) and said light injection elements (10) are adjacent to said light guide sheet (11) by their second ends (10.2) and extend along the first direction (y).

7. A lighting device (2) for a vehicle, said lighting device (2) comprising at least one light guide (1) according to any one of the preceding claims and at least one light source (20) arranged opposite said light mixing zone (13).

8. Luminous device (2) according to the preceding claim, according to which said at least one light source (20) is composed of several distinct emitters.

Images