FR3142791A1 - Flexible surface light guide for vehicle - Google Patents

Abstract

The invention relates to a surface and flexible light guide (1) for a vehicle (3) comprising: - a plurality of groups (10) of light injection elements (100) and a light guide sheet (11) , each group (10) being coupled with at least one light source (20), characterized in that: - the light guide sheet (11) comprises a plurality of regions (110), at least one emission zone light (111) being integrated in at least one region (110), said light guide sheet (11) being adjacent to said light injection elements (100), each group (10) being configured to illuminate a region ( 110) in said light guide sheet (11), and in that the light injection elements (100) of a group (10) illuminating a region (110) have a length (Lg') different from that light injection elements (100) of the other groups (10) illuminating another region (110). Figure for abstract: figure 2

Description

Flexible surface light guide for vehicle

The present invention relates to a light guide for a vehicle. It finds a particular but non-limiting application in motor vehicles.

An example known to those skilled in the art of a light guide is illustrated in the and is referenced 5. This light guide 5 is used for example in decorative objects to illuminate them, and it includes:
- a plurality of groups 50 of light injection elements 500, each group 50 being coupled with at least one light source 60,
- a light guide sheet 51 comprising a plurality of regions 510 and a light emitting area 511 integrated in a region 510, said light guide sheet 51 being adjacent to said light injection elements 500, each group 50 being configured to illuminate the region 510 in said light guide sheet 51.

Each group 50 is designed in the same way: the light injection elements 500 of a group 50 are adjacent to each other and have different and increasing lengths as one moves away from the light sources 60. Furthermore, each light injection element 500 of a group 50 has the same length as another light injection element 500 of another group 50. The light injection elements 500 of a group 50 are folded and superimposed so as to form a stack with one end. Each light injection element 500 therefore comprises a fold. Said at least one light source 60 coupled to said group 50 is configured to emit light rays which enter through the end of the stack and can thus be propagated in said light injection elements 500 up to the light guide sheet 51. As illustrated in the , said at least one light source 60 coupled to each group 500 is arranged on an electronic support 61. Thus, there are as many electronic supports 61 as there are groups 50 of light injection elements 500. As illustrated in the , there are three groups 50 of light injection elements 500 and therefore three electronic supports 61. Two electronic supports 61 are located between two groups 50. Each light source 60 has a luminous power of approximately 80 lumens.

A disadvantage of this state of the art is that the light sources 60 used are of too low power for a motor vehicle application and that there is no space between the groups 50 of light injection elements 500 to have the light sources of greater power and which are consequently of larger size with suitable electronic supports and suitable heat sinks (also of larger size) to dissipate the heat produced by these light sources of greater power.

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

For this purpose, the invention proposes a flexible surface light guide for a vehicle comprising:
- a plurality of groups of light injection elements and a light guide sheet, each group being coupled with at least one light source, characterized in that:
- the light guide sheet comprises a plurality of regions, at least one light emitting area being integrated in at least one region, said light guide sheet being adjacent to said light injection elements, each group being configured to illuminate a region in said light guide sheet,
and in that the light injection elements of one group illuminating one region have a different length than the light injection elements of the other groups illuminating another region.

Thus, as will be seen in detail later, thanks to the different length of each light injection element from one group to another, the light sources that are coupled to the light injection elements can be offset far from the light guide sheet, which allows them to be placed in a less confined space and thus to overcome space limitations. It is thus possible to have an electronic support large enough to accommodate all the light sources as well as a heat sink of suitable size to cool the light sources.

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

According to a non-limiting embodiment, in each group of light injection elements, said light injection elements are folded so as to form a stack with a thickness adapted to an emission surface of a light source, the stack having an entry surface configured to receive light emitted by the light source.

According to a non-limiting embodiment, said light guide is transparent.

According to a non-limiting embodiment, said at least one light-emitting zone forms at least one pattern.

According to a non-limiting embodiment, said plurality of groups of light injection elements is arranged on the same side of said light guide sheet and thus forms a first set of light injection elements.

According to a non-limiting embodiment, the plurality of groups of light injection elements is arranged on a first side of said light guide sheet and thus forms a first set of light injection elements and according to which the light guide comprises a second set identical to the first set, said second set being arranged on a second side of said light guide sheet opposite the first side symmetrically with the first set relative to said light guide sheet.

According to a non-limiting embodiment, said light sources are coupled with at least one light collimator. This makes it possible to reduce light losses from the light sources and thus to increase the efficiency of light propagation.

According to a non-limiting embodiment, a set of light sources coupled with a group is supplied with a different current from the other sets of light sources coupled with the other groups. This makes it possible to create animations.

According to a non-limiting embodiment, the light sources are semiconductor light sources.

According to a non-limiting embodiment, said light sources can be activated independently of one another. This makes it possible to create animations.

There is further provided a lighting device for a vehicle characterized in that it comprises at least one light guide according to any one of the preceding characteristics, a plurality of light sources and at least one heat sink.

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

According to a non-limiting embodiment, the light sources are arranged on the same electronic support.

According to a non-limiting embodiment, the light sources are arranged on the same plane of said same electronic support.

According to a non-limiting embodiment, each light source is arranged on a different plane of said same electronic support from the other light sources.

According to a non-limiting embodiment, said light device comprises at least two superimposed light guides oriented in opposite directions.

According to a non-limiting embodiment of the light device,
- in each group of light injection elements, the light injection elements are folded so as to form a stack with a thickness adapted to an emission surface of a light source, the stack having an input surface receiving light emitted by the corresponding light source,
- the light injection elements are dimensioned so that the input surfaces are at the same level when the light injection elements of each of the groups are folded.

The invention and its various applications will be better understood by reading the description which follows and by examining the figures which accompany it:

is a schematic illustration of a light guide according to the prior art, said light guide comprising groups of light injection elements coupled to light sources and a light guide sheet,

is a schematic illustration of a light guide of a vehicle, said light guide comprising three groups of light injection elements coupled to light sources and a light guide sheet comprising regions and at least one light emission zone, the three groups of injection elements being arranged on the same side of the light guide sheet according to a first variant embodiment of a non-limiting embodiment of the invention,

is a schematic illustration of a light guide of a vehicle, said light guide comprising six groups of light injection elements coupled to light sources and a light guide sheet comprising regions and at least one light emission zone, the six groups of injection elements being arranged on the same side of the light guide sheet according to a first variant embodiment of a non-limiting embodiment of the invention,

is a schematic illustration of a light guide of a vehicle, said light guide comprising six groups of light injection elements coupled to light sources and a light guide sheet comprising regions and at least one light emission zone, the six groups of injection elements being arranged on both sides of the light guide sheet according to a second variant embodiment of a non-limiting embodiment of the invention,

is an enlarged view of a portion of light injection elements of a light guide according to Figures 2, 3, 4, or 5,

is a view of one face of a stack of light injection elements within a single group of light injection elements of a light guide according to Figures 2, 3, 4, or 5,

illustrates said light guide of the with said light injection elements which are unfolded according to a non-limiting embodiment,

is an enlarged perspective view of certain light injection elements of a group of a light guide according to figures 2, 3, 4 or 5, according to a non-limiting embodiment,

is a schematic illustration of the light guide of the , said light guide sheet comprising three regions with three light emitting zones forming a pattern, according to a first non-limiting embodiment of the pattern,

is a schematic illustration of the light guide of the , said light guide sheet comprising three regions with three light emitting zones forming three patterns, according to a second non-limiting embodiment of the pattern,

is a schematic illustration of a lighting device of a vehicle, said lighting device comprising said light guide of the , light sources, an electronic support, and a heat sink, the light sources being arranged on said electronic support according to a first variant embodiment of a first non-limiting embodiment of the lighting device,

is a schematic representation of the lighting device of the , said light device further comprising a light collimator, according to a non-limiting embodiment,

is a schematic illustration of a lighting device of a vehicle, said lighting device comprising said light guide of the , light sources, an electronic support, and a heat sink, the light sources being arranged on said electronic support according to a second variant embodiment of a first non-limiting embodiment of the lighting device,

is a schematic illustration of a lighting device of a vehicle, said lighting device comprising said light guide of the comprising two sets of groups of light injection elements arranged on either side of said light guide sheet, light sources, two electronic supports, and two heat sinks, according to a second non-limiting embodiment of the light device,

is a schematic illustration of a lighting device of a vehicle, said lighting device comprising two light guides of the superimposed, light sources, four electronic supports, and four heat sinks, according to a third non-limiting embodiment of the lighting device.

Identical elements, by structure or function, appearing in different figures retain, unless otherwise specified, the same references.

The light guide 1 according to the invention is described with reference to FIGS. 2 to 15. The light guide 1 is a light guide for a vehicle 3. In a non-limiting embodiment, the vehicle 3 is a motor vehicle. By motor vehicle, we mean 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 3 is thus otherwise called a motor vehicle 3. In a non-limiting variant embodiment, the vehicle 3 is a thermal vehicle or an electric vehicle.

The light guide 1 is surface and flexible. Thus, it can adapt to any type of flat or curved surface. A surface light guide is understood to mean an optical guiding element one of the dimensions of which is much smaller than the other two dimensions in space, for example smaller by one or more orders of magnitude. Here, the thickness e of the light guide 1 is much smaller than its length Lg and its width La. In a non-limiting embodiment, the light guide 1 has a thickness e (illustrated in the ) between 10 and 1000 micrometers. In a non-limiting variant embodiment, the thickness e is between 50 and 1000 micrometers. In a non-limiting example, the thickness e is 50 micrometers. The light guide 1 is thus very thin.

In a non-limiting embodiment, the light guide 1 is transparent. The light guide 1 is thus otherwise called transparent film 1. The fact that it is transparent allows light to pass through. The fact that the light guide 1 is transparent also allows a pattern (called a manufacturer pattern) integrated into the front face or the headlight or the rear light of the motor vehicle 3 to be seen through said light guide 1, if the latter integrate one, when the light guide 1 is off, namely when it does not emit light. This also allows the color of the bodywork of the motor vehicle 3 to be kept when the light guide 1 is off. At night, to illuminate the manufacturer pattern, the light guide 1 comprises a pattern 111 (described below) which may be identical to the manufacturer pattern and which thus allows the manufacturer pattern to be illuminated.

Due to the fact that it is surface-mounted and flexible and transparent, the light guide 1 is configured to be placed on the front face of the motor vehicle 3 (as illustrated in the ) or on a projector (as illustrated in the ) or a rear light of the motor vehicle 3 (as illustrated in the ). In a first non-limiting embodiment, the light guide 1 is glued. In a first non-limiting variant embodiment, the surface (such as an outer glass of the front face, the headlight, the rear light) on which the light guide 1 is placed comprises an adhesive surface for gluing the light guide 1. In a second non-limiting variant embodiment, it is the rear face of the light guide 1 which comprises an adhesive surface and which is glued behind a decorative piece. In a third non-limiting variant embodiment, the two faces of the light guide 1 are adhesive. In a second non-limiting embodiment, the light guide 1 is not glued, it is taken between the outer glass and the decorative piece.

In a non-limiting embodiment, the light guide 1 is made of polycarbonate (PC), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TUP), or polyethylene terephthalate (PET). Such materials make it possible to produce a flexible and transparent light guide 1.

As illustrated in Figures 2, 3 and 4, in a non-limiting embodiment, the light guide 1 extends in its width La along a z axis and in its length Lg along a y axis substantially perpendicular to the x axis. It will be noted that the width La and the length Lg can be equal.

As illustrated in Figures 2, 3 and 4, the light guide 1 comprises:
- a plurality of groups 10 of light injection elements 100, and
- a light guiding sheet 11 comprising a plurality of regions 110.

The light guide sheet 11 extends in a first direction y and in a second direction z. In the unfolded state, the light injection elements 100 extend mainly in the first direction y in a non-limiting embodiment. The dimension measured in this first direction y is thus considered to be the length Lg' of the light injection element 100 as illustrated in the .

It will be noted that during the manufacturing process of the light guide 11, the light injection elements 100 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 100 along the y axis illustrated in the and thus form the different light injection elements 100 and the light guide sheet 11. Thus, the light injection elements 100 remain attached to the light guide sheet 11 on one of their ends 100.1.

The large sheet from which the light guide sheet 11 and the light injection elements 100 are formed comprises a flexible film and shell layers arranged on either side of the flexible film. A layer of glue or adhesive is located between the flexible film and the shell layers. The layer of glue or adhesive has a refractive index different from that of the flexible film so as to propagate the light rays in the flexible film by total internal reflection, hence the use of the name “light guide” to designate the entire guide sheet and the light injection elements.

The groups 10 and the light injection elements 100 are described below.

In a non-limiting embodiment, the number of groups 10 is between two and twenty.

It will be noted that in the examples illustrated in Figures 7 to 13 and 15, only eight light injection elements 100 per group 10 have been shown compared to Figures 2, 4 and 14 which illustrate ten.

Each group 10 is configured to illuminate a region 110 (described later) in the light guide sheet 11.

A group 10 may comprise one or more light injection elements 100. In a non-limiting embodiment, it comprises between three and ten light injection elements 100. In a non-limiting variant embodiment, it comprises ten light injection elements 100. In the non-limiting example of FIGS. 2 and 4, the light guide 1 comprises three groups 10 and each group comprises ten light injection elements 100. In the non-limiting example of FIGS. , the light guide comprises six groups 10 and each group comprises five light injection elements 100. Compared to the example of FIGS. 2 and 4, the number of groups 10 has been doubled and the number of light injection elements 100 has consequently been divided per group 10. For the sake of clarity, only one light injection element 100 has been referenced.

Each group 10 is coupled with at least one light source 20. Said at least one light source 20 is configured to emit light rays R (illustrated in FIGS. 6 and 8) which will propagate by total reflection in the light injection elements 100 of the group 10 so as to bring light to the light guide sheet 11 which is adjacent to the light injection elements 100 and which will thus illuminate the regions 110 of the light guide sheet 11. In a non-limiting embodiment, each group 10 is coupled with a plurality of light sources 20. In another non-limiting embodiment, each group 10 is coupled with a single light source 20. This latter non-limiting embodiment is taken as a non-limiting example in the remainder of the description and in the non-limiting examples of FIGS. 2, 3 and 4.

As illustrated in the , a light injection element 100, otherwise called a coupling bar 100, or light bar 100, or simply bar 100, is configured to receive the light rays R emitted by the light source 20 which propagate and are entirely reflected in said light injection element 100. The light injection element 100 is of rectangular or square section. The light injection element 100 comprises a length Lg', a width La' (illustrated in the ) and a thickness e (illustrated on the ). Its thickness e is that of the thickness e of the light guide 1. The light injection element 100 comprises two ends 100.1, one of which is directly adjacent and attached to the light guide sheet 11 and the other is configured to face said light source 20. The light rays R emitted by the light source 20 enter through one end 100.1 and are transmitted to the other end 100.1 then to the light guide sheet 11. For the sake of clarity, only the ends 100.1 of the light injection element 100 ₈ of a group 10 have been referenced.

There illustrates three groups 10 of eight light injection elements referenced 100 ₁ to 100 ₈ . As illustrated in the , a light injection element 100 of a group 10 is adjacent to at least one other light injection element 100 of said group 10. The light injection elements 100 at the ends of the group 10 (namely 100 ₁ and 100 ₈ ) are adjacent with a single light injection element 100 of said group 100 while the so-called intermediate light injection elements 100 which are not arranged at the ends of said group 100 (namely 100 ₂ to 100 ₇ ) are adjacent with two other light injection elements 100 of said group 10.

As illustrated in the , the light injection elements 100 of the same group 10 extend along the y axis when they are unfolded and have different positions pj j=1 to N, with N being an integer in the +z direction. The further a light injection element 100 is from the light sources 20, the greater its position pj. Thus, as illustrated in the non-limiting example of the , the light injection element 100₈ at position p8 while the light injection element 100₁ at position p1.

When the light guide 1 is arranged on the front face of the motor vehicle 2 for example, the surface of the light injection elements 100 is perpendicular to the x axis. It will be noted that the x axis corresponds to the vehicle axis Ox.

As illustrated in the , the light injection elements 100 are composed of:
- a main part 100.2 which extends along the y axis, namely in the first direction of the light guide sheet 11 described later, and
- an end portion 100.3 which extends along the z-axis, namely in the second direction of the light guide sheet 11 described later. The end portion 100.3 is connected to the light guide sheet 11. The two portions 100.2 and 100.3 are separated by a fold 100.4. The end portion 100.3 extends after the fold 100.4. In a non-limiting embodiment, the fold 100.4 is a right-angled fold. The length Lg' of a light injection element 100 is the sum of the dimension of the main portion 100.2 and the end portion 100.3.

There illustrates the end portions 100.3, the main portions 100.2 of light injection elements 100 of a group 10 and the fold 100.4 which separates them. illustrates the end portions 100.3 of ten light injection elements 100 of a group 10 and a light source 20 coupled to said group 110.

The light injection elements 100 of the same group 10 have different lengths Lg’. For reasons of clarity, only the length Lg’ of the light injection elements 100₈ has been referenced on the . Thus, a light injection element 100 of a group 10 has a length Lg' different from the other light injection elements 100 of the same group 10. This allows them to be folded so that their end portions 100.3 form a stack 103 with a flat entry surface 103.1 as illustrated in the . The end portion 100.3 of a light injection element 100 extends after the fold 100.4. In a non-limiting embodiment, the fold 100.4 is a right-angle fold.

Each light injection element 100 thus comprises a fold 100.4. The entry surface 103.1 of the stack 103 is formed by one of the ends 100.1 of each of the light injection elements 100 of the group 10 which are the ends of their terminal part 100.3.

As illustrated in the , in each group 10, the light injection elements 100 are folded so that their end portions 100.3 form the stack 103 with a thickness E adapted to an emission surface of the light source 20. The thickness E is the sum of the thicknesses e of each light injection element 100 whose end portions 100.3 form the stack 103. The stack 103 has an entry surface 103.1 formed by the ends of the end portions 100.3 of each of the light injection elements 100 of the group 110, and configured to receive the light emitted by the light source 20.

As illustrated in the and 8, in a non-limiting embodiment, the light source 20 coupled to the group 10 is arranged opposite the entry surface 103.1 of the stack 103. The light rays R from the light source 20 enter via this entry surface 103.1 and thus propagate in the light injection elements 100. The light rays R are totally reflected inside the light injection elements 100 and redirected via the folds 100.4 towards the light guide sheet 11.

It will be noted that the further away from the light source 20 of a group 10, the greater the length Lg' of the light injection elements 100. Thus, the furthest light injection element 100 ₈ has the greatest length Lg' while the closest light injection element 100 ₁ has the smallest length Lg'. This makes it possible to obtain an input surface 103.1 for the stack 103 which is planar.

The light injection elements 100 of the same group 10 have the same width La’

When there are several groups 110, the light injection elements 100 are arranged in the same way for all the groups 10, namely:
- they are adjacent to each other and are folded with a fold 100.4 so as to form the stack 103 with its flat entry surface 103.1,
- the further away from the light source 20 of a group 10, the greater the length Lg' of the light injection elements 100. Thus, the length Lg' of the light injection elements 100 increases progressively in the direction of distance from the light source 20. Thus, the light injection element 100 furthest from the light source 20 has the greatest length Lg' while the closest light injection element 100 has the smallest length Lg'. This makes it possible to obtain an input surface 103.1 for the stack 103 which is planar. Thus, the light injection elements 100 of the same group 10 have different lengths Lg'.

The light injection elements 100 of a group 10 illuminating a region 110 have a length Lg’ different from that of the light injection elements 100 of the other groups 10 illuminating another region 110.

In particular, a light injection element 100 at a position pj in a group 10 illuminating a region 110 has a length Lg' different from a light injection element 100 of another group illuminating another region 110 at the same respective position pj. This makes it possible to offset the light sources 20 coupled with each group 10 far from the light guide 1 so as to be able to bring them back to a single given location and so as to be able to arrange them on a single electronic support 21 as illustrated in FIG. . Having only one electronic support 21 makes it possible to reduce the number of connectors since a single connector is sufficient. By reducing the number of connectors, the number of electrical connection harnesses associated with a single electrical connection harness is reduced. In a non-limiting embodiment, the electronic support 21 is a PCBA (“Printed Circuit Board Assembly”) card. In a non-limiting example, the light sources 20 which are thus offset are arranged between 10 and 50 centimeters from the light guide 10.

At the level of the motor vehicle application 3, this makes it possible to relocate the light sources 20 with the electronic support 21 to a location behind the front face where there is space or behind the headlight or the rear light where there is space. Thus, it is possible to use light sources 20 of high luminous power adapted to the motor vehicle application 3 and which are consequently larger than those of the prior art. It is thus possible to use a heat sink 22 (illustrated in the ) adapted to dissipate the heat emitted by the high-power light sources 20 without being limited in space. In a non-limiting embodiment, the light sources 20 have a luminous flux of 400 lumens per light source 20. It is also possible, in a non-limiting embodiment, to use in addition to the heat sink 22 a fan (not shown) for cooling the light sources 20.

It will be noted that the fact of being able to use light sources 20 of higher luminous power makes it possible to have a large surface area for the light guide sheet 11 (described later) with a plurality of regions 110 and thus to be able to effectively illuminate the different regions 110. Thus, the light guide 1 can be used for example for the front face, the headlight or the rear light of the motor vehicle 3 which extend over a large surface area.

It will be noted that having the light injection elements 100 of a group 10 illuminating a region 110 which have a length Lg' different from that of the light injection elements 100 of the other groups 10 illuminating other regions 110 also allows, when these light injection elements 100 are folded, their respective end portion 100.3 to arrive at different locations along the y axis (if they are projected onto the y axis) from those of the other groups 10, unlike the prior art, they arrive at the same position along the y axis (if they are projected onto the y axis) for all the groups. In the prior art, the input surfaces of the stacks are aligned along the z axis, whereas in the case of the light guide 1 described, the input surfaces 103.1 of the stacks 103 are not aligned along the z axis.

In the non-limiting example of the in which the light guide 1 comprises three groups 10, in a non-limiting embodiment, the group 10 furthest away (otherwise called third group 10) from the light sources 20 and which illuminates a region 110 comprises light injection elements 100 of length Lg' different from that of the light injection elements 100 respectively at the same position pj of the group 10 closest to the light sources 20 (otherwise called first group 10) which illuminates another region 110. In particular, as illustrated in the , bar 100₁ of the third group 10 which is at position p1 includes a length Lg’ greater than that of the bar 100₁ from the first group 10 which is at the same position p1, and the bar 100₈ of the third group 10 which is at position p8 includes a length Lg’ greater than that of the bar 100₈ of the first group 10 which is at the same position p8. It is the same with the intermediate bars 100₂to 100₇ respective to the respective positions p2 to p7. This makes it possible to be sure that the entry surfaces 103.1 of the stacks 103 of the two groups 10 arrive at different locations along the y axis.

The intermediate group 10 (otherwise called second group 10) located between the two other groups 10 and which illuminates a region 110 different from the two other groups 10 comprises light injection elements 100 of length Lg' different from that of the light injection elements 100 respectively at the same position pj of the closest group 10. In particular, the bar 100₁ of the second group 10 which is at position p1 comprises a length greater than that of the bar 100₁ from the first group 10 which is at the same position p1, and the bar 100₈ from the second group 10 to position p8 includes a length Lg’ greater than that of the bar 100₈ from the first group 10 to the same position p8. The same is true with the intermediate bars 100₂to 100₇ respective to the respective positions p2 to p7. This makes it possible to be sure that the entry surfaces 103.1 of the stacks 103 arrive at different locations of the two groups 10 along the y axis.

In a non-limiting embodiment, the light injection elements 100 have a thickness e of approximately 50 µm (micrometers). In a non-limiting embodiment, the light injection elements 100 have a width La’ between 1 and 20 millimeters. In a non-limiting embodiment, the light injection elements 100 have a length Lg’ between 100 and 500 millimeters.

In a non-limiting embodiment, the light injection elements 100 of a group 10 have a width La’ different from the light injection elements 100 of the other groups 10. This makes it possible to illuminate different surfaces of regions 110 per group 10 and therefore to have a number of different and/or different sized light sources 20.

The light guide sheet 11 is now described below.

As illustrated in Figures 2, 3, and 4, the light guide sheet 11 comprises:
- a plurality of regions 110,
- at least one light emitting zone 111 integrated in at least one region 110.

The light guide 1 being a transparent flexible surface, the guide sheet 11 is consequently a surface, flexible and transparent. The 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 the headlight or the rear light of the motor vehicle 3.

The light guide sheet 11 is adjacent and attached to the light injection elements 100. Each region 110 is configured to be illuminated by a different group 10 of light injection elements 100. The different regions 110 are illuminated by groups 10 of light injection elements 100 of different sizes due in particular to their different length Lg’.

The light guide sheet 11 further comprises at least one light mixing region 112. The light which emerges from the same group 10 of light injection elements 100 will be mixed in the light mixing region 112, which allows homogeneous illumination of the light emission zone 111 of the corresponding region 110.

A region 110 comprises said at least one light emitting area 111.

A light-emitting zone 111 is a zone through which the light generated by the light rays R of the light source 20 of the group 10 emerges from the light guide sheet 11. In particular, it emerges in the +x direction, namely substantially parallel to the vehicle axis Ox, towards the outside of the front face of the motor vehicle 2 in a non-limiting example taken.

In a non-limiting embodiment, said at least one light-emitting zone 111 forms at least one pattern, otherwise called pattern 111. In a non-limiting example, the pattern 111 has a size of 30 x 30 centimeters. In a non-limiting example, the pattern 111 is a logo or part of a logo. Thus, in this case, an illuminated logo is obtained. In a non-limiting embodiment, the pattern is formed of microstructures. Such microstructures may have a general shape of a bump or hollow in non-limiting examples, on which the light rays R are reflected. The microstructures are nanometric structures. In a non-limiting embodiment, the pattern 111 is identical to the manufacturer pattern seen previously. In this case, the pattern 111 covers the manufacturer pattern when the light guide 1 is placed on the front face. Thus, this highlights the manufacturer pattern when the light source(s) 20 are activated.

In the non-limiting examples of FIGS. 9 and 10, the light guide sheet 11 comprises three regions 110 and light emitting zones 111 integrated respectively in the three regions 110.

There illustrates a first non-limiting example of an illuminated pattern which is a logo. A first light-emitting zone 111 here forms an L of the logo, a second light-emitting zone 111 here forms an O and a G of the logo, and a third light-emitting zone 111 here forms an O of the logo.

There illustrates a second non-limiting example of an illuminated pattern that includes diamonds, circles, and squares. A first light emitting area 111 forms the diamonds, a second light emitting area 111 forms the circles, and a third light emitting area 111 forms the squares.

The assembly comprising light guide 1, light sources 20, electronic support 21 and heat sink 22 form a lighting device 2 illustrated in FIGS. 11 to 15.

The lighting device 2 thus comprises:
- at least one light guide 1 described above,
- a plurality of light sources 20 arranged on at least one electronic support 21, and
- at least one heat sink 22.

A group 10 of the light guide 1 is coupled with one or more light sources 20. The assembly of a group 10 of injection elements 100 and one or more associated light sources 20 is otherwise called an input coupler 13. There is thus an input coupler 13 associated with each region 110 of the light guide sheet 11. For reasons of clarity, only one input coupler 13 has been referenced in FIGS. 11 to 13.

In a non-limiting embodiment, the light sources 20 are semiconductor light sources. In a non-limiting embodiment, the semiconductor light sources are 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” in English), OLEDs (“Organic LEDs” in English), AMOLEDs (“Active-Matrix-Organic LEDs” in English), or FOLEDs (“Flexible OLEDs” in English).

In a non-limiting embodiment, the light sources 20 can be activated independently of one another. This makes it possible to illuminate each region 110 of the light guide sheet 10 independently of one another and thus to create animations. Thus, in the example of the , we can make an animated illuminated logo. So, in the example of the , we can alternately illuminate the diamonds, circles, and squares to create an animation.

According to an exemplary embodiment, the number of light sources 20 is adapted according to the size (length Lg', width La', thickness e) of the light injection elements 100 of a group 10. Thus, it is possible to have the same number of light sources 20 per group 10 or different numbers of light sources 20 per group 10. Similarly, it is possible to have different sizes of light sources 20 per group 10 or light sources 20 of the same size for all the groups 10. In the non-limiting examples of the figures, there is the same number of light sources 20 per group 10, namely here only one, and the light sources 20 are of the same size. In a non-limiting example, the emission surface of a light source 20 is 1 mm ² . According to another exemplary embodiment, the number of light element injection elements 100 is adapted to the number of light sources 20 used to meet the need for the luminance to be achieved.

Figures 11, 12 and 13 illustrate a first embodiment of the lighting device 1 in which:
- said light device 1 comprises a single light guide 1,
- the groups 10 of light injection elements 100 of this light guide 1 are arranged on the same side of the light guide sheet 11 and thus form a first set of light injection elements 100,
- the light sources 20 of all the groups 10 are arranged on the same electronic support 21.

Since the light injection groups 100 are all arranged on the same side of the light guide sheet 11, the corresponding light sources 20 are all arranged on the same side and can therefore be placed on the same electronic support 21. Only one electronic support 21 is therefore necessary. Consequently, only one heat sink 22 is used. Thus, in this first non-limiting embodiment, the lighting device 2 comprises only one heat sink 22. Of course, it would be possible to have a plurality of electronic supports.

In the non-limiting example illustrated in FIGS. 11 and 12, there are three groups 10 and three light sources 20 respectively coupled to the three groups 10, and the three groups 10 are arranged on the same side 11.1 of the light guide sheet 11. In the non-limiting example, the light guide sheet 11 comprises three regions 110. Each group 10 illuminates a different region 110.

In a first non-limiting variant embodiment of this first non-limiting embodiment illustrated in the , the light sources 20 are arranged on the same plane of said same electronic support 21. Thus, each light source 20 is located at the same distance d from the three input surfaces 103.1 of the three stacks 103 formed by the light injection elements 100 of the three respective groups 10.

Since there are groups 10 of light injection elements 100 with different lengths Lg', there is a possible risk of inhomogeneity between the groups 10. Indeed, the path traveled by the light generated by the light rays R is shorter in the group 10 closest to the light sources 20 than for the two other groups 10 further away. For the most distant group 10, whose light injection elements 100 are longer, there may therefore be a loss of efficiency in the propagation of the light. In order to maintain the efficiency of the propagation of light, in a non-limiting embodiment of this first variant, a set of light sources 20 coupled to a group 10 is supplied with a current different from the other sets of light sources 20 coupled with the other groups 10. It is recalled that a set can comprise one or more light sources 20, in the present case, it comprises only one light source 20. Thus, in the non-limiting example illustrated in the , the light source 20 of a group 10 is supplied by a different current from the light source 20 of the other groups 10. This amounts to having a specific current, here referenced i, i', i'', per region 110 of the light guide sheet. The further a group 10 is from the light sources 20, the stronger the associated current i will be to maintain the efficiency of the propagation of the light. The current i'' is thus the strongest and the current i is thus the weakest. In a non-limiting example, the current i'' is 260 mA for the furthest group 10, the current i' is 255 mA for the intermediate group and the current i is 250 mA for the closest group 10. This guarantees the uniformity of overall illumination over all the regions 11 of the light guide sheet 11.

In a non-limiting embodiment of the first non-limiting embodiment variant illustrated in the , the light device 2 further comprises at least one light collimator 23 coupled with the light sources 20. Said at least one light collimator 23 is arranged between the light sources 20 and the stacks 103 described above. In particular, it is arranged opposite the entry surface 103.1 of a stack 103. In a non-limiting embodiment, the light collimator 23 is an optical lens. As illustrated in the , the light device 2 comprises three light collimators 23 coupled respectively to the light source 20 of the three groups 10 of light injection elements 100. Each light collimator 23 is arranged opposite a stack 103, in particular its entry surface 103.1. The light collimators 23 make it possible to reduce the light losses of the light sources 20 and thus to increase the efficiency of the propagation of the light when the light injection elements 100 have a small thickness e (between 1 and 5 mm). Furthermore, the light collimators 23 serve as intermediate parts between the light sources 20 and the entry surfaces 103.1 of the stacks 103. This makes it possible to prevent the light sources 20 from being too close to the entry surfaces 103.1 which would risk burning them. Since the light sources 20 are offset from the light guide sheet 11, there is space to add such light collimators 23.

In a second non-limiting variant embodiment of this first non-limiting embodiment illustrated in the , each light source 20 is arranged on a different plane of said same electronic support 21 from the other light sources 20 and is supplied by the same current i. The electronic support 21 thus comprises bearings and each light source 20 is on a different bearing. Thus, each light source 20 is at different distances, here d, d', d'', from the three input surfaces 103.1 of the three stacks 103 described above. This makes it possible to maintain the efficiency of the propagation of the light. The light source 20 coupled to the group 10 which is furthest from the light sources 20 is the one which is arranged at the smallest distance d''. The light source 20 coupled to the group 10 which is closest to the light sources 20 is the one which is arranged at the greatest distance d. In the non-limiting case of the three light sources 20, in a non-limiting example, the light source 20 of the most distant group 10 is arranged at a distance d'' of 0.4mm (millimeters) from the input surface 103.1 of its corresponding stack 103. The light source 20 of the closest group 10 is arranged at a distance d of 0.5mm from the input surface 103.1 of its corresponding stack 103. Finally, the light source 20 of the intermediate group 10 is at a distance d' of 0.45mm from the input surface 103.1 of its corresponding stack 103. The distance d, d', d'' of the light sources relative to the input surface 103.1 of the corresponding stack 103 is thus adjusted according to the length Lg' of the light injection elements 100 so as to drive the light sources 20 with the same current i.

There illustrates a second embodiment of the lighting device 1 in which:
- said light device 1 comprises a single light guide 1,
- the plurality of groups 10 of light injection elements 100 is arranged on a first side 11.1 of said light guide sheet 11 and thus forms a first set of light injection elements 100 and a second set identical to the first set is arranged on a second side 11.2 of said light guide sheet 11 opposite the first side 11.1 symmetrically with the first set relative to the light guide sheet 11,
- the light sources 20 coupled to the first set are arranged on the same first electronic support 21, and the light sources 20 coupled to the second set are arranged on the same second electronic support 21 different from the first electronic support 21.

Thus, in the non-limiting example of the , there are two sets of three groups 10 including a first set of three groups 10 located on one side 11.1 of the light guide sheet 11 and a second set of three other groups 10 located on the other side 11.2 opposite the side 11.1. The light guide sheet 11 comprises two light mixing regions 112 opposite each of the two sets of three groups 10. In the non-limiting example, the light guide sheet 11 comprises three regions 110. Each group 10 of a set illuminates a different region 110 of another group 10 of the same set. A group 10 of the first set illuminates the same region of another group 10 of the second set.

This second non-limiting embodiment makes it possible to increase the illumination of the regions 110 since there is illumination coming from two sides of the light guide sheet 11 instead of just one in the case of the first non-limiting embodiment. This also makes it possible to reduce the light power of the light sources 20 so as to have two smaller and less bulky heat sinks 21 than in the case of the first non-limiting embodiment where there is only one heat sink 21 in a non-limiting embodiment. In the illustrated non-limiting example, there are twice as many light sources 20 as in the first non-limiting embodiment since there are twice as many groups 10. The first non-limiting variant embodiment (light sources 20 on the same plane) of the first non-limiting embodiment and the second non-limiting variant embodiment (light sources 20 on different planes) of the first non-limiting embodiment can be applied to the second non-limiting embodiment, taken in isolation or in combination.

There illustrates a third embodiment of the light device 1 in which said light device 1 comprises at least two light guides 1 superimposed and oriented in opposite directions. In the non-limiting example of the , the light device 1 comprises two light guides 1 as described in the second embodiment of the , namely which each comprises two sets of groups 10 of light injection elements 100, each set being arranged on one side 11.1 and the other opposite side 11.2 of the light guide sheet 11. The two light guides 1 are oriented oppositely in that the entry surfaces 103.1 of their stacks 103 are respectively arranged along the other two opposite sides 11.3 and 11.4. Thus, on the , it can be seen that the two input surfaces 101.3 of the two stacks 103 of the first light guide 1 are arranged along a third side 11.3 of the light guide sheet 11, and the two input surfaces 101.3 of the two stacks 103 of the second light guide 1 are arranged along a fourth side 11.4 of the light guide sheet 11, said fourth side 11.4 being opposite the third side 11.3. In the illustrated non-limiting example, there are twice as many light sources 20 as in the second non-limiting embodiment, thus there are four electronic supports 21 and four heat sinks 22. The light guide sheet 11 comprises four light mixing regions 112 opposite each of the two sets of the three groups 10 of each light guide 1. For reasons of clarity of the figure, only one light source 20 per electronic support 21 has been referenced and only four input surfaces 101.3 have been referenced. In the non-limiting example, the light guide sheet 11 comprises three regions 110. Each region 110 is illuminated by four groups 10. In particular, each region 110 is illuminated by a group 10 of a first set and by a group 10 of a second set of each light guide 11.

This third non-limiting embodiment makes it possible to create an animation with two superimposed patterns for example. Thus, in a non-limiting example, the two light guides 1 are arranged on a rear light of the motor vehicle 3 such as a rear position light. In this case, the first light guide 1 may comprise a first light-emitting zone 111 forming a first pattern and the second light guide 1 may comprise a second light-emitting zone 111 forming a second pattern superimposed on the first pattern. When the position light is on, then the light sources 20 associated with the first light guide 1 are activated and the first pattern is thus illuminated, while the light sources 20 associated with the second light guide 1 are deactivated; the second pattern is thus not illuminated. When the driver brakes, then the light sources 2 associated with the second light guide 1 are activated and the second pattern can thus also be illuminated and thus overlight the first pattern if the two patterns are identical. When the driver brakes, the light sources 2 associated with the second light guide 1 are activated and the second pattern can thus also be illuminated and added in addition to the first pattern.

Of course, the description of the invention is not limited to the embodiments described above and to the field described above. Thus, the invention can be applied to any application other than the vehicle application, requiring a large light emission surface. Thus, in a third variant embodiment of the first non-limiting embodiment, instead of having light sources on different planes with steps on the electronic support 21 or different currents to supply the light sources 20 which are on the same plane, it is possible to have light sources 20 arranged on the same plane of the electronic support 21 and input surfaces 103.1 offset from each other relative to the x axis. They would no longer be aligned on the x axis. Thus, the input surface 103.1 of the stack 103 of the group 10 furthest from the light sources 20 would be closer than the other two and the input surface 103.1 of the stack 103 of the group 10 closest to the light sources 20 would be furthest from the other two along the x axis.

Thus, the invention described presents in particular the following advantages:
- it allows to have a flexible 1 surface light guide suitable for vehicle applications with large surfaces to be illuminated,
- it makes it possible to have a light device 2 with light sources 20 which have sufficient light power to illuminate the light guide sheet 11 of a light guide 1,
- it makes it possible to reduce the number of electronic supports compared to the prior art to arrive at only one electronic support 21 when all the light sources 20 are located on the same side of the light guide sheet 11, which makes it possible to reduce the size, weight, and cost of the lighting device 2,
- by reducing the number of electronic supports, it makes it possible to reduce the number of associated connectors as well as the number of associated electrical connection harnesses, which makes it possible to reduce the size, weight, and cost of the lighting device 2,
- by moving the light sources 20 away from the light guide sheet 11, it makes it possible to place the light sources 20 in an unconfined space where there is space and thus it makes it possible to use light sources 20 of higher luminous power than those of the prior art if desired; it also makes it possible to place in an unconfined space one or more heat sinks 21 adapted to the size and luminous power of the light sources 20; it is thus possible to increase the size of the heat sink(s) compared to the prior art;
- it makes it possible to obtain more efficient and more significant lighting for the light guide sheet 11 and its regions 110,
- it makes it possible to increase the light emission surface, namely the total surface of the regions 110 of the light guide sheet 11 which are illuminated without reducing the efficiency of the lighting,
- it allows you to have an illuminated logo, and animated if necessary.

Claims (11)

Flexible surface light guide (1) for vehicle (3) comprising:
- a plurality of groups (10) of light injection elements (100) and a light guide sheet (11), each group (10) being coupled with at least one light source (20), characterized in that:
- the light guide sheet (11) comprises a plurality of regions (110), at least one light emitting area (111) being integrated in at least one region (110), said light guide sheet (11) being adjacent to said light injection elements (100), each group (10) being configured to illuminate a region (110) in said light guide sheet (11),
and in that the light injection elements (100) of a group (10) illuminating a region (110) have a length (Lg') different from that of the light injection elements (100) of the other groups (10) illuminating another region (110). Light guide (1) according to claim 1, wherein in each group (10) of light injection elements (100), said light injection elements (100) are folded so as to form a stack (103) with a thickness (e) adapted to an emission surface (s1) of a light source (20), the stack (103) having an entry surface (103.1) configured to receive light emitted by the light source (20). Light guide (1) according to any one of the preceding claims, wherein said light guide (1) is transparent. Light guide (1) according to any one of the preceding claims, wherein said at least one light emitting zone (111) forms at least one pattern. Light guide (1) according to any one of the preceding claims 1 to 4, according to which said plurality of groups (10) of light injection elements (100) is arranged on the same side (11.1) of said light guide sheet (11) and thus forms a first set of light injection elements (100). Light guide (1) according to any one of the preceding claims 1 to 4, wherein the plurality of groups (10) of light injection elements (100) are arranged on a first side (11.1) of said light guide sheet (11) and thus form a first set of light injection elements (100) and wherein the light guide (1) comprises a second set identical to the first set, said second set being arranged on a second side (11.2) of said light guide sheet (11) opposite the first side (11.1) symmetrically with the first set with respect to said light guide sheet (11). Luminous device (2) for vehicle (3) characterized in that it comprises at least one light guide (1) according to any one of the preceding claims, a plurality of light sources (20) and at least one heat sink (22). Luminous device (2) according to claim 7, according to which the light sources are arranged on the same electronic support (21). Luminous device (2) according to claim 8, according to which the light sources (20) are arranged on the same plane of said same electronic support (21). Luminous device (2) according to claim 8, according to which each light source (20) is arranged on a different plane of said same electronic support (21) from the other light sources (20). Luminous device (2) according to any one of claims 7 to 10, according to which said luminous device (2) comprises at least two light guides (1) superimposed and oriented in opposite directions.