FR3148077A1 - Flexible light guide light module for segmented display - Google Patents

Abstract

The present invention relates to a light module (100) comprising a transparent and flexible light guide (110) and comprising guide strips (120.1-120.6). First parts of the guide strips of a light guide are arranged next to each other and second parts of the guide strips are bent in a direction substantially normal to the first parts such that the second parts of the guide strips at least partially overlap. Each second part comprises a first sub-part (211.1-211.6) and a second sub-part (212.1-212.6). The second sub-part is adapted to extract light according to a predefined pattern. The light module further comprises a light source (130.1-130.6) associated with each guide strip and adapted to inject light rays into the first part of the guide strip. Fig. 3

Description

Flexible light guide light module for segmented display

The present invention relates to the field of light guide light modules, in particular light modules with a flexible light guide, for displaying a light pattern, in particular for displaying a segmented dynamic light pattern.

It is now common to implement lighting functions in all types of equipment, particularly in equipment for motor vehicles, particularly for information signalling purposes, for aesthetic purposes of personalisation or to create an atmosphere.

A light module can enable a segmented display with a light source dedicated to each segment of the module, the light module comprising several aligned light sources. The successive activation of the sources then allows the creation of a gradual dynamic pattern, by dynamic activation of some of the segments of the light module.

For this purpose, it may be planned to align LED sources, for “Light Emitting Diode” in English. Each LED corresponds to a segment, and the light module includes as many LEDs as segments. Several dozen LEDs can thus be used in such a light module.

Dedicated optical elements, including optical lenses in particular, are also arranged opposite the LEDs in order to improve the rendering of the light module, in particular so that the LEDs are not seen by an external observer as point sources but rather as a uniformly illuminated surface.

The use of a large number of LEDs and dedicated optical elements results in a significant bulkiness and also leads to the production of a heavy light module, which can weigh several kilograms.

Such drawbacks make it impossible to integrate these light modules into equipment in a constrained environment, as is the case in particular in automotive equipment.

Thus, there is a need for a light module capable of producing a segmented display of a light pattern, the light module being light, compact, if possible flexible and allowing good homogeneity of the light pattern displayed.

The present invention improves the situation.

A first aspect of the invention relates to a light module comprising at least one light guide of an at least partially transparent and flexible material, said light guide comprising at least two guide strips, each guide strip comprising a first part and a second part. The first parts of the guide strips of a light guide are arranged next to each other. The second parts of the guide strips of a light guide are bent in a direction substantially normal to the first parts such that the second parts of the guide strips at least partially overlap. Each second guide strip part of a light guide comprises a first sub-part and a second sub-part, the first sub-part is capable of guiding light rays from the first part of the guide strip to the second sub-part, and the second sub-part is capable of extracting light according to a predefined pattern. The light module further comprises a light source associated with each guide strip of a light guide, each light source associated with a guide strip being capable of injecting light rays into the first part of the guide strip.

Thus, the invention makes it possible to use a flexible light guide with several guide strips, the second parts of which are superimposed. It is thus possible to produce a segmented display in the second sub-parts of the guide strips. The integration of such a light module is easier than in the prior art, because the light sources are offset, and because the light guide is flexible, and can therefore be mounted on a non-planar support, such as a curved support. In addition, the light module according to the invention does not require optical elements as in the prior art, which considerably reduces the size and weight of the light module. In addition, the use of a light guide allows a surface display with good homogeneity.

According to embodiments, each light guide may have a thickness of between 12 and 1000 micrometers, in particular between 25 and 1000 micrometers, in particular between 50 and 500 micrometers, in particular between 50 and 125 micrometers.

Such thicknesses make it possible to obtain a light guide with high flexibility, facilitating its integration into any type of equipment, in particular on a non-flat support, for example curved, of such equipment. In addition, the light module according to the invention is all the lighter and more compact as the light guide is thin.

Additionally, each light source may be of the MicroLED or MiniLED type, with at least one dimension of the light source less than 1000 micrometers, in particular less than 500 micrometers, in particular less than 125 micrometers.

Thus, the light sources are of similar dimensions to the thickness of the guide strips, which allows light injection with little light loss, and therefore improves the luminous efficiency of the light module.

According to embodiments, the second sub-portions may have different lengths from each other.

Additionally, the second sub-portion of the guide strip having the longest first sub-portion may be shorter than the second sub-portion of the guide strip having the shortest first sub-portion.

Thus, the differences in length of the second sub-parts can compensate for the differences in length of the first sub-parts, which are unavoidable due to the folding of the second parts. Such compensation makes it possible to facilitate the manufacture of the light module, in particular when the light guide is obtained by a roll-to-roll manufacturing process, the guide strips being cut from a given portion of a roll of material capable of guiding the light in its thickness, by total internal reflection. Indeed, the light guide of the light module according to the invention can then be cut from a first rectangular portion of material, which allows mass production by a roll-to-roll process with a minimization of material losses.

Additionally or alternatively, according to a first embodiment, the second outermost sub-part of the light guide may be the second shortest sub-part of a light guide.

Thus, at least some of the second sub-portions may comprise an area which does not face any other second sub-portion of the light guide, thereby improving the light output of the light module.

Note that the second outermost sub-part is equivalently the second furthest sub-part from a support on which the light module is arranged.

Alternatively, according to a second embodiment, the second outermost sub-portion of the light guide may be the second longest sub-portion.

This allows a uniform visual rendering of the light module for an observer outside the light module, when no light source is activated.

According to embodiments, each second sub-part of a guide strip is capable of extracting light homogeneously across the entire second sub-part.

The second sub-parts having different sizes, it is then possible to have a gradual dynamic display by successive activation of the different light sources.

Alternatively, each second sub-part is capable of extracting light in a given area of the second sub-part, and the given areas of the second sub-parts of a light guide do not overlap.

Thus, each guide strip is dedicated to illuminating a given area of the light module, and combinations of light sources can be activated to achieve a dynamic display, including a gradual dynamic display.

According to a third embodiment, the light module may comprise a first light guide and a second light guide, a first set of light sources and a second set of light sources. The first light guide comprises at least two first guide strips and the second light guide comprises at least two second guide strips. The second portions of the first guide strips of the first light guide are bent in a direction substantially normal to the first portions, in a first sense, such that the second portions of the first guide strips at least partially overlap. The second portions of the second guide strips of the second light guide are bent in a direction substantially normal to the first portions, in a second sense opposite the first sense, such that the second portions of the second guide strips at least partially overlap. The first light guide and the second light guide are arranged such that a slice of the second longest sub-portion of the first guide strips faces a slice of the second longest sub-portion of the second guide strips.

It is thus possible to increase the surface dimension of the displayed pattern, in particular when the light module displays a dynamic pattern, in particular a gradual and/or symmetrical dynamic pattern.

According to embodiments, each light guide comprises a polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, polyethylene terephthalate, PET, or silicone film.

Such materials allow good conduction of light rays by total internal reflection, with good flexibility and a high degree of transparency.

• positionnement d’un rouleau de matériau sur un tapis entraîné par un dispositif d’entraînement, ledit matériau étant apte à guider la lumière par réflexion totale interne;
• translation dudit rouleau de manière de manière à traiter une première portion du rouleau de matériau;
• formation de microstructures dans la première portion du rouleau de matériau, de manière à former des zones d’extraction lumineuses réparties selon des motifs prédéterminés dans des bandes de positions de la première portion;
• découpe de la première portion de manière à séparer la première portion du reste du rouleau de matériau;
• découpe de la première portion en plusieurs bandes de guidage correspondant aux bandes de position de la première portion, les bandes de guidage comprenant une première partie et une deuxième partie s’étendant longitudinalement, la découpe des bandes de guidage séparant au moins les deuxièmes parties des bandes de guidage;
• pliage des deuxièmes parties des bandes de guidage dans une direction normale aux premières parties, de manière à ce que les deuxièmes parties des bandes de guidage se superposent au moins partiellement;
• agencement de sources de lumière de manière à ce que chaque source de lumière soit apte à injecter de la lumière dans la première partie de chaque bande de guidage.

A second aspect of the invention relates to a method of manufacturing a light module according to the first aspect of the invention, comprising the following steps:

• positioning a roll of material on a belt driven by a drive device, said material being capable of guiding light by total internal reflection;
• translating said roller so as to process a first portion of the roll of material;
• forming microstructures in the first portion of the roll of material, so as to form light extraction zones distributed according to predetermined patterns in position bands of the first portion;
• cutting the first portion so as to separate the first portion from the remainder of the roll of material;
• cutting the first portion into a plurality of guide strips corresponding to the position strips of the first portion, the guide strips comprising a first portion and a second portion extending longitudinally, the cutting of the guide strips separating at least the second portions of the guide strips;
• bending the second parts of the guide strips in a direction normal to the first parts, such that the second parts of the guide strips at least partially overlap;
• arrangement of light sources such that each light source is capable of injecting light into the first part of each guide strip.

Each second guide strip portion comprises a first sub-portion and a second sub-portion, the first sub-portion being capable of guiding light rays from the first guide strip portion to the second sub-portion, and wherein the microstructures are formed in the second sub-portion so as to extract light into the second sub-portion according to one of the predetermined patterns.

Following the formation of microstructures, the method may further comprise adding at least one layer of glue to at least a portion of the first portion, and preferably two layers of glue, one above and one below the portion of the first portion.

The part in which the glue layer is added can advantageously correspond to the second part of the guide strips described later.

Advantageously, an at least partially transparent protective layer, which may be made of PC or another material, can be added to each layer of glue, by lamination.

Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawings in which:

illustrates a cross-sectional view of elements of a light module according to embodiments of the invention;

illustrates a front view of a guide sheet of a light module according to embodiments of the invention;

illustrates a front view of a light module according to a first embodiment;

illustrates a front view of a light module according to a second embodiment;

illustrates a front view of a light module according to a third embodiment;

illustrates a side view of a system for manufacturing a light guide of a light module according to embodiments of the invention;

is a diagram illustrating the steps of a method of manufacturing a light module according to embodiments of the invention.

The description focuses on the characteristics that distinguish the light module and the signaling device from those known in the state of the art.

There presents elements of a light module 100 according to embodiments of the invention.

The light module 100 comprises at least one light guide 110, forming a guide sheet, which can be flexible and capable of receiving light rays via at least one light injection edge 114 and of returning the light rays in a direction Z substantially normal to a surface of the light guide 110 which thus extends in an XY plane on the . A light guide sheet is a light guide of which one of the dimensions is much smaller than the other two dimensions in space, for example one or more orders of magnitude smaller. As illustrated in the , we consider here a light guide 110 whose thickness along the Z axis is at least two orders of magnitude less than its dimensions along the XY plane in which the light guide 110 extends.

The light guide 110 may comprise a film 111 at its core, which may be flexible, comprising the light injection edge 114, being capable of guiding the light rays in a global direction X, and comprising a set of microstructures 113 capable of returning the light rays guided in the film 111 outside the flexible light guide 110, in particular in one or more directions substantially along the Z axis.

The film 111 may be a substrate film made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, polyethylene terephthalate, PET, silicone, or even glass. The film 111 may have a thickness e, i.e. a dimension along the Z axis, of between 12 and 1000 micrometers. More precisely, the thickness of the film 111 may be between 25 and 1000 micrometers, in particular between 50 and 500 micrometers, and preferably between 50 and 125 micrometers. Alternatively, it is the guide sheet 110 which has a thickness of between 12 and 1000, in particular between 25 and 1000 micrometers, in particular between 50 and 500 micrometers, and preferably between 50 and 125 micrometers.

The aforementioned materials, associated with a low thickness e as described above, make it possible to obtain a flexible and transparent film 111. Other materials may be provided for the composition of the film 111. However, it is preferable according to the invention to provide deformable and transparent materials.

A thin coating of microstructures 113 may be created on one of the faces of the film 111, or in the film 111. The microstructures are formed on the surface of the film, or in the film, in a distribution making it possible to produce a light pattern. According to the invention, several light patterns are produced, with a light pattern for each guide strip, as will be better understood in light of the description of the following figures. Each light pattern is obtained from light extraction zones which are zones of the film 111 comprising microstructures 113. The light pattern may also comprise dark zones, which are zones of the film 111 not comprising microstructures 113. The respective arrangements, as well as the respective shapes, of the light extraction zones and the dark zones together form the light pattern of a light guide 110.

Microstructures 113 are structures, or irregularities, of the flexible film, at least one of the dimensions of which is less than a few micrometers. For example, the microstructures 113 may be of the order of 50 micrometers in diameter and 1 or 2 micrometers in height. The microstructures thus also cover nanometric structures. Such sizes of microstructures 113 make it possible to ensure high transparency of the flexible film 111. In particular, a transparency of the order of 97% can be obtained in practice by the use of microstructures 113. Alternatively, the guide sheet may be semi-transparent or partially transparent.

The microstructures are capable of redirecting the light injected into the light guide in one or more directions different from the injection direction along the X axis. In particular, at least some of the redirected light rays are redirected in a direction substantially parallel to the Z axis, in particular in a direction directed towards the outside of the light module 100. In practice, such microstructures are capable of redirecting the guided light rays in all directions in space, in a Lambertian manner.

There is no restriction on how the microstructures 113 are formed on the face of the film 111. The microstructures 113 can be obtained by adding or removing material from the flexible film.

For example, the microstructures can be obtained by embossing by applying a roller having irregularities to mechanically print microstructures on the surface of the film 111. Alternatively, the microstructures 113 can be obtained by irradiation, for example by UV rays, by baking a polymer in contact with a mold, a roller or any other surface comprising irregularities capable of forming the microstructures 113 by shape complementarity.

Alternatively, the microstructures 113 are formed at locations where a coating of the flexible film made of a material having a low refractive index is removed from the flexible film, so as to form microstructures by material removal. In this case, the microstructures are holes or gaps. Optionally and additionally, surface or volumetric, prismatic, reflective, diffracting or diffusing additional elements may be added in the holes or gaps to form the microstructures 113.

The microstructures 113 can be obtained by treating the surface of the film 111, in which case they are of the same material as the film 111 or correspond to an absence of material of the film 111. Such treatment can be by mechanical or laser tracing, by laser ablation, by sandblasting, by exposure to radiation, by chemical treatment or by any other treatment making it possible to obtain irregularities in a controlled manner on the face of the film 111.

Alternatively or in a complementary manner, the microstructures 113 are elements exogenous to the film added to the face of the film 111.

The microstructure coating 113 may in particular have a thickness along the Z axis of less than 20 micrometers.

The density of the microstructures 113 may vary in the light extraction zones depending on their distance from the light injection edge 114.

“Pattern” means any predefined spatial distribution or distribution of the light intensity emitted by the light module. In particular, reference is made here to a two-dimensional or one-dimensional pattern. A pattern may thus comprise a homogeneous distribution of light over the entirety of a given area of the light guide, in particular in the second sub-parts of guide strips which will be described in the following. The pattern may also be a two-dimensional shape or symbol obtained by contrast between the light extraction areas and the dark areas of the light guide 110. The pattern may also comprise several shapes or symbols. Alternatively, a pattern covers a predefined spatial distribution of the light intensity not showing a general shape, such as a distribution inducing a cloud of light points.

As will be better understood from reading what follows, the patterns displayed according to the invention are preferably symbols making it possible to indicate signaling information for the motor vehicle.

The flexible guide sheet 110 may further comprise one or two optional protective layers 112.1 and 112.2, which make it possible to mechanically protect the film 111. In addition, at least one of the protective layers 112.1 and 112.2 may comprise an anti-UV treatment, preferably the protective layer 112.1 through which the light rays returned by the microstructures 113 are emitted, making it possible to protect the film against UV rays, once the microstructures 113 have been created. Without such UV protection, the pattern projected by the guide sheet 110 is likely to degrade over time, in particular when exposed to sunlight.

The film 111 and the protective layers 112.1 and 112.2 are shown spaced apart on the , for illustrative purposes only. It will be understood, however, that the protective layers 112.1 and 112.2 may be attached to the film 111, in particular by lamination.

The propagation of light rays in the 111 film is done by total internal reflection thanks to the difference between the refractive index of the 111 film and that of a layer of glue or adhesive applied to at least one face of the flexible film.

The assembly of the film 111 with the protective layers 112.1 and 112.2 can be done by gluing. Specifically, a layer of glue is located between the film 111 and each protective layer 112.1 and 112.2, and this on both sides of the film to adhere the protective layers to the film 111.

The selected glue is transparent and has a refractive index different from, in particular lower than, that of the film so as to allow total internal reflection in the film 111. For example, the glue may comprise silicone or acrylic. In other words, due to the difference in refractive indices, the light rays propagating in the film 111 undergo total reflection when they encounter the interface between the film 111 and the glue layer with an angle of incidence lower than the normal incidence. Thus, the guide sheet is capable of guiding light by total internal reflection of this light, for example from an entry zone, here the injection edge 114, to an exit zone.

The guide sheet 110 may be flexible, it is not necessarily included in a plane but can be curved, depending on the position in which it is placed and the mechanical constraints applied to it.

There presents a top view, in an XY plane of a light guide 110 making it possible to obtain a light module 100 according to embodiments of the invention.

According to the invention, the light guide 110 is cut into at least two guide strips. In particular, in the example of the , given for illustrative purposes only, the light guide 110 is at least partially cut into six guide strips 120.1 to 120.6. A manufacturing method for obtaining a light module 100 according to the invention will be described in the following.

A guide strip is called a guide sheet, that is to say a guide with a dimension several orders smaller than the other two dimensions, called principal dimensions, one of the principal dimensions of which is at least five times smaller, and preferably at least ten times smaller, than the other principal dimension.

In the XYZ reference frame of the , each of the guide strips 120.1 to 120.6 has a width W along the Y axis which is at least five times, and preferably at least ten times, less than a length L extending, on the , along the X axis.

On the , the guide strips 120.1 to 120.6 all have the same length L, which facilitates their manufacture since they can be obtained from a roll-to-roll process, from a roll of film 111, and with cutting along the Y axis facilitated and with minimal losses, to obtain a light guide, followed by at least partial separation of the guide strips 120.1 to 120.6 by cuts along the X axis.

The guide strips 120.1 to 120.6 according to the invention comprise two parts, namely a first part 200 and a second part 210.

The guide strips 120.1 to 120.6 are separated at least in the second part 210, so as to be able to be folded between the first and second parts 200 and 210 and so that the second parts 210 of the guide strips 120.1 to 120.6 overlap, as will be better understood in light of the description of the .

In the first part 200 of the guide strips 120.1 to 120.6, the guide strips 120.1 to 120.6 can be joined, or can be partially cut. Each guide strip 120.1 to 120.6 is however capable of guiding light rays which are injected into the injection edge 114 in a Y-position interval specific to the guide strip.

Thus, even if the guide strips 120.1 to 120.6 are joined or partially joined in the first part 210, a light ray entering a given guide strip cannot reach another guide strip which is consecutive to the given guide strip.

According to the invention, the first parts 200 of the guide strips 120.1 to 120.6 do not comprise a light extraction zone, that is to say that the first parts 200 do not have any pattern 113 allowing the light rays to be deflected towards the outside of the light guide 110, in particular in directions substantially along the Z axis, in the direction of the positive Zs and/or in the direction of the negative Zs. Thus, all the light rays injected into the first part 200 of a guide strip 120.1 to 120.6 are guided towards the second part 210.

The second portions 210 of the guide strips 120.1 to 120.6 comprise a first sub-portion 211.1-211.6 and a second sub-portion 212.1-212.6, the first sub-portion 211.1-211.6 being comprised between the first portion 210 and the second sub-portion 212.1-212.6.

The first sub-part 211.1-211.6 of each guide strip 120.1 to 120.6 is capable of guiding the light rays received from the first part 210 to the second sub-part 212.1-212.6. The first sub-part 211.1-211.6 does not include any light extraction zone, i.e. no microstructure 113 capable of returning the light outside the guide sheet 110.

The second sub-part 212.1-212.6 of each guide strip 120.1 to 120.6 comprises at least one light extraction zone, i.e. a set of microstructures 113 distributed according to a given pattern between a set of X positions of the second sub-part 212.1-212.6.

The first subpart 211.1-211.6 of a given guide strip 120.1-120.6 has a different length from the first subpart 211.1-211.6 of another guide strip. Furthermore, when the guide strips 120.1 to 120.6 have the same length L, the second subpart 212.1-212.6 of a given guide strip has a different length from the second subpart 212.1-212.6 of another guide strip.

On the , the first subpart 211.1-211.6 and the second subpart 212.1-212.6 shown are the first subparts of the first guide strip 120.1 and the sixth guide strip 120.6. However, the first subparts of the other guide strips 120.2-120.5 are shorter than the first subpart 211.1 and longer than the first subpart 211.6. Similarly, when the guide strips 120.1 to 120.6 have the same length L, the second subparts of the other guide strips 120.2-120.6 are longer than the second subpart 212.1 of the first guide strip 120.1 and shorter than the second subpart 212.6 of the sixth guide strip 120.6.

As a variant of the light guide 110 shown in the , the guide strips 120.1 to 120.6 may be cut so as to have different respective lengths Li. In particular, the length Li of each strip of index length i may be greater than the length Li-1 of the strip of index length i-1.

There illustrates a light module 100 according to a first embodiment of the invention.

According to the invention, the guide sheet 110 from which the guide strips 120.1 to 120.6 are cut has a thickness e and is made of one of the aforementioned materials, so that the guide strips 120.1 to 120.6 are flexible. The invention then provides for folding the second part 210 of each guide strip 120.1 to 120.6 along the Y axis, so that the second parts 210 of the guide strips 120.1 to 120.6 overlap, at least partially. In particular, the first sub-parts 211.1-211.6 overlap completely, while the second sub-parts 212.1-212.6 overlap at least partially. In the example of the figures, the guide strips 120.1-120.6 have the same length L and the second sub-parts 212.1-212.6 only partially overlap.

• La deuxième sous-partie 212.1 de la première bande de guidage 120.1 est complètement superposée avec toutes les deuxièmes sous-parties des autres bandes de guidage 120.2 à 120.6, c’est-à-dire que toutes les deuxièmes sous-parties des autres bandes de guidage 120.2 à 120.6 comprennent l’ensemble des positions en X et Y de la deuxième sous-partie 212.1. Dans le premier mode de réalisation, la deuxième sous-partie 212.1 est au-dessus des deuxièmes sous-parties des autres bandes de guidage 120.2 à 120.6, c’est-à-dire à une position en Z supérieure aux deuxièmes sous-parties des autres bandes de guidage 120.2 à 120.6. Comme il sera décrit ultérieurement, le module lumineux 100 selon le premier mode de réalisation est apte à émettre des rayons lumineux au moins dans le sens des Z positifs. Autrement dit, dans le premier mode de réalisation, la deuxième sous-partie 212.1 est la plus externe des deuxièmes sous-parties;
• La deuxième sous-partie 212.2 de la deuxième bande de guidage 120.2 est complètement superposée avec toutes les deuxièmes sous-parties des bandes de guidage 120.3 à 120.6, c’est-à-dire que toutes les deuxièmes sous-parties des bandes de guidage 120.3 à 120.6 comprennent l’ensemble des positions en X et Y de la deuxième sous-partie 212.2. La deuxième sous-partie 212.2 est au-dessus, selon l’axe Z, des deuxièmes sous-parties des bandes de guidage 120.3 à 120.6;
• La deuxième sous-partie 212.3 de la troisième bande de guidage 120.3 est complètement superposée avec toutes les deuxièmes sous-parties des bandes de guidage 120.4 à 120.6, c’est-à-dire que toutes les deuxièmes sous-parties des bandes de guidage 120.4 à 120.6 comprennent l’ensemble des positions en X et Y de la deuxième sous-partie 212.3. La deuxième sous-partie 212.3 est au-dessus, selon l’axe Z, des deuxièmes sous-parties des bandes de guidage 120.4 à 120.6;
• La deuxième sous-partie 212.4 de la quatrième bande de guidage 120.4 est complètement superposée avec toutes les deuxièmes sous-parties des bandes de guidage 120.5 et 120.6, c’est-à-dire que toutes les deuxièmes sous-parties des bandes de guidage 120.5 et 120.6 comprennent l’ensemble des positions en X et Y de la deuxième sous-partie 212.4. La deuxième sous-partie 212.4 est au-dessus, selon l’axe Z, des deuxièmes sous-parties des bandes de guidage 120.5 et 120.6; et
• La deuxième sous-partie 212.5 de la cinquième bande de guidage 120.5 est complètement superposée avec la deuxième sous-partie 212.6 de la bande de guidage 120.6, c’est-à-dire que la deuxième sous-partie 212.6 de la bande de guidage 120.6 comprend l’ensemble des positions en X et Y de la deuxième sous-partie 212.5. La deuxième sous-partie 212.5 est au-dessus, selon l’axe Z, de la deuxième sous-partie 212.6 de la bande de guidage 120.6.

In particular, in the first embodiment of the :

• The second sub-portion 212.1 of the first guide strip 120.1 is completely superimposed with all the second sub-portions of the other guide strips 120.2 to 120.6, i.e. all the second sub-portions of the other guide strips 120.2 to 120.6 comprise all the X and Y positions of the second sub-portion 212.1. In the first embodiment, the second sub-portion 212.1 is above the second sub-portions of the other guide strips 120.2 to 120.6, i.e. at a Z position higher than the second sub-portions of the other guide strips 120.2 to 120.6. As will be described later, the light module 100 according to the first embodiment is capable of emitting light rays at least in the positive Z direction. In other words, in the first embodiment, the second subpart 212.1 is the outermost of the second subparts;
• The second sub-part 212.2 of the second guide strip 120.2 is completely superimposed with all the second sub-parts of the guide strips 120.3 to 120.6, that is, all the second sub-parts of the guide strips 120.3 to 120.6 comprise all the X and Y positions of the second sub-part 212.2. The second sub-part 212.2 is above, along the Z axis, the second sub-parts of the guide strips 120.3 to 120.6;
• The second sub-part 212.3 of the third guide strip 120.3 is completely superimposed with all the second sub-parts of the guide strips 120.4 to 120.6, that is, all the second sub-parts of the guide strips 120.4 to 120.6 comprise all the X and Y positions of the second sub-part 212.3. The second sub-part 212.3 is above, along the Z axis, the second sub-parts of the guide strips 120.4 to 120.6;
• The second sub-portion 212.4 of the fourth guide strip 120.4 is completely superimposed with all the second sub-portions of the guide strips 120.5 and 120.6, i.e. all the second sub-portions of the guide strips 120.5 and 120.6 comprise all the X and Y positions of the second sub-portion 212.4. The second sub-portion 212.4 is above, along the Z axis, the second sub-portions of the guide strips 120.5 and 120.6; and
• The second sub-portion 212.5 of the fifth guide strip 120.5 is completely superimposed with the second sub-portion 212.6 of the guide strip 120.6, i.e. the second sub-portion 212.6 of the guide strip 120.6 comprises all of the X and Y positions of the second sub-portion 212.5. The second sub-portion 212.5 is above, along the Z axis, the second sub-portion 212.6 of the guide strip 120.6.

In other words, more generally, that is to say whatever the number N of guide strips, N being greater than or equal to 2, each guide strip completely overlaps with the guide strip which is directly below. Preferably, and as shown in the , each second sub-portion of a given guide strip is shorter than the second sub-portion of the guide strip located below the given guide strip.

Note that the guide strips are not necessarily in an XY plane since they are flexible. In particular, they can be arranged on a non-planar curved support, not shown in the figure. .

According to the invention, each second guide strip sub-part 120.1-120.6 is capable of returning light according to a different pattern in other second sub-parts. The light patterns produced by the second guide strip sub-parts 120.1-120.6 may differ in their size, their light intensity, their position and/or their shape. The light patterns may be produced by creating the microstructures 113 at given positions, forming said light pattern, of the second sub-parts 212.1 to 212.6. The second sub-parts 212.1 to 212.6 are capable of extracting light and emitting light rays in the half-space of the positive Zs, in particular in a main direction along the Z axis or along a direction forming an angle of less than 15° with the Z axis.

According to a first example, each of the second sub-parts 212.1 to 212.6 is capable of extracting light rays according to a homogeneous light pattern over the entirety of the second sub-part.

Thus, according to the first example, the second sub-parts 212.2 to 212.6 other than the second sub-part 212.1 positioned furthest to the outside of the light module 100, emit partially through the second sub-parts below which they are located. For example, for the second sub-part 212.2, the light rays extracted in the zone 220.2 can exit directly from the light module 100 while the light rays extracted in the complementary zone of the zone 220.2, that is to say the zone of the second sub-part 212.2 which is located below the second sub-part 212.1, pass through the second sub-part 212.1. The same applies to the second sub-parts 212.3 to 212.6.

It is thus preferable to have guide strips 120.1-120.6 that are at least partially transparent so that the light extracted by the second sub-parts 212.2 to 212.6 can pass through the sub-part(s) located above without causing too much loss of light intensity.

For this purpose, the material of the guide strips 120.1 to 120.6 and their thickness may be chosen so as to have a high level of transparency, in particular greater than 90% and preferably greater than 95%, for example equal to 97%.

• La deuxième sous-partie 212.1 est apte à extraire des rayons lumineux de manière homogène sur l’ensemble de la deuxième sous-partie 212.1;
• La deuxième sous-partie 212.2 est apte à extraire des rayons lumineux de manière homogène uniquement dans la zone 220.2 de la deuxième sous-partie 212.2 qui n’est pas superposée avec la deuxième sous-partie 212.1 située directement au-dessus;
• La deuxième sous-partie 212.3 est apte à extraire des rayons lumineux de manière homogène uniquement dans la zone 220.3 de la deuxième sous-partie 212.3 qui n’est pas superposée avec la deuxième sous-partie 212.2 située directement au-dessus;
• La deuxième sous-partie 212.4 est apte à extraire des rayons lumineux de manière homogène uniquement dans la zone 220.4 de la deuxième sous-partie 212.4 qui n’est pas superposée avec la deuxième sous-partie 212.3 située directement au dessus;
• La deuxième sous-partie 212.5 est apte à extraire des rayons lumineux de manière homogène uniquement dans la zone 220.5 de la deuxième sous-partie 212.5 qui n’est pas superposée avec la deuxième sous-partie 212.4 située directement au-dessus;
• La deuxième sous-partie 212.6 est apte à extraire des rayons lumineux de manière homogène uniquement dans la zone 220.6 de la deuxième sous-partie 212.6 qui n’est pas superposée avec la deuxième sous-partie 212.5 située directement au-dessus.

According to a second example:

• The second subpart 212.1 is capable of extracting light rays homogeneously across the entire second subpart 212.1;
• The second subpart 212.2 is capable of extracting light rays homogeneously only in the area 220.2 of the second subpart 212.2 which is not superimposed with the second subpart 212.1 located directly above;
• The second subpart 212.3 is capable of extracting light rays homogeneously only in the area 220.3 of the second subpart 212.3 which is not superimposed with the second subpart 212.2 located directly above;
• The second subpart 212.4 is capable of extracting light rays homogeneously only in the area 220.4 of the second subpart 212.4 which is not superimposed with the second subpart 212.3 located directly above;
• The second subpart 212.5 is capable of extracting light rays homogeneously only in the area 220.5 of the second subpart 212.5 which is not superimposed with the second subpart 212.4 located directly above;
• The second subpart 212.6 is capable of extracting light rays homogeneously only in the area 220.6 of the second subpart 212.6 which is not superimposed with the second subpart 212.5 located directly above.

In other words, more generally according to the second example, each second sub-part comprises a zone above which no other second sub-part of another guide strip is superimposed, the second sub-part being able to extract light rays according to a homogeneous pattern in said zone. The relative term “above” is expressed relative to a support on which the light module 100 is placed. The second sub-part 212.6 in contact with the support is that which is located the lowest of the stack of second sub-parts 212.1-212.6.

Areas 220.2 to 220.6 have a square format of W by W, when all guide strips 120.1 to 120.6 have the same length L, as shown in the . However, when the length Li of each strip of index length i is greater than the length Li-1 of the strip of index length i-1, the areas may be rectangular in shape.

In other words, in the second example, the light patterns are exclusive and complementary to each other, and are formed at X-Y positions that are disjoint, whereas in the first example, the light patterns partially overlap.

The light module 100 according to the first embodiment further comprises a set of light sources 130.1 to 130.6 respectively capable of injecting light into the injection edge 114 of the guide strips 120.1 to 120.6.

Thus, each light source is opposite the injection slice 114 of a given guide strip.

The light sources 130.1 to 130.6 are preferably electroluminescent sources, of the LED type, for “Light Emitting Device”. In particular, in order to minimize light losses, and thus maximize the light output corresponding to the ratio between the luminous intensity of the emitted rays, and the luminous intensity of the light rays injected into the guide strip which is associated with the light source, each light source has at least one dimension of the same order of magnitude as the thickness e of each guide strip. In particular, each light source may have dimensions of less than 150 micrometers, in particular less than 100 micrometers. Light sources of the miniLED or microLED type make it possible to achieve such dimensions, and the light sources 130.1 to 130.6 are thus preferably miniLEDs or microLEDs.

The light sources 130.1 to 130.6 can be arranged on the same support 140, which can be a printed circuit, also called PCB for “Printed Circuit Board” in English.

The control module 150 may further comprise a control unit 150 capable of individually controlling each of the light sources 130.1 to 130.6. In particular, the control unit 150 may control the light sources 130.1 to 130.6 via the printed circuit 140.

Optionally, the light module 100 may further comprise collimation optical elements 131.1 to 131.6, each collimation optical element being arranged opposite one of the light sources 130.1 to 130.6 so as to collimate the light rays emitted from the light source towards the injection edge of the guide strip associated with the light source. The light output of the light module 100 is thus improved.

The light module 100 is thus capable, by selective control of the light sources 130.1 to 130.6, of producing a dynamic light pattern by gradual display.

In the first example detailed above, a gradual display can be achieved by successively activating each of the light sources 130.1 to 130.6, that is to say that when one light source is activated, the other light sources are deactivated.

Thus, in the first example, the control unit 100 can determine the light source to be activated based on a received control signal, the other light sources being deactivated.

In the second example detailed above, a gradual display can be realized by cumulatively activating the light sources 130.1 to 130.6, that is, the first light source 130.1 is activated, then the first light source 130.1 and the second light source 130.2 are activated at the same time, then the first, second and third light sources 130.1-130.3 are activated together, and so on.

Thus, in the second example, the control unit 100 can determine the combination of at least one light source to be activated based on a received control signal.

In the first embodiment of the , the second example has the advantage of better homogeneity, since each second sub-part is able to extract light and redirect the light rays outside the light module 100, without the light rays passing through the other second sub-parts. Thus, the light sources 130.1 to 130.6 can have the same power. Alternatively, the first light source 130.1 can have a greater power when the second sub-part 212.1 has a larger surface area than the areas 220.2 to 220.6.

There presents a light module 100 according to a second embodiment of the invention.

The 100 light module of the is identical to that of the , but the light module 100 according to the second embodiment is arranged differently. In particular, the light module 100 according to the second embodiment is obtained by a symmetry around the Y axis of the light module 100 of the . In other words, in the light module 100 according to the second embodiment, the second largest sub-part 212.6 is above the other second sub-parts 212.1 to 212.5, and the second sub-part 212.1 is below the other sub-parts 212.2 to 212.6.

As for the first embodiment, the second sub-parts 212.1 to 212.6 are also capable of extracting light and emitting light rays in the half-space of the positive Zs, in particular in a main direction along the Z axis or along a direction forming an angle of less than 15° with the Z axis.

The two examples detailed above for the first embodiment are applicable to the second embodiment.

According to the first example, each of the second sub-parts 212.1 to 212.6 is capable of extracting light rays according to a homogeneous light pattern over the entirety of the second sub-part.

According to the second example, each second sub-part comprises an area below (and not above, as in the first embodiment) which no other second sub-part of another guide strip is superimposed, the second sub-part being capable of extracting light rays according to a homogeneous pattern in said area.

In the second embodiment, the second example no longer has the advantage of homogeneity that was allowed in the first embodiment. For example, the light rays extracted from the area 220.2 pass through the second sub-portions 212.3, 212.4, 212.5 and 212.6 before exiting the light module 100, while the light rays extracted from the area 220.4, for example, pass through the second sub-portions 212.5 and 212.6.

• Des surfaces respectives des deuxièmes sous-parties 212.1 à 212.6;
• Des niveaux de transparence des deuxièmes sous-parties 212.1 à 212.6, qui permettent de déterminer la perte d’intensité lumineuse induite lorsque des rayons lumineux extraits d’une deuxième sous-partie traversent une autre sous-partie.

In contrast, according to the first example, the control unit 150 activates only one of the light sources and each guide strip is capable of extracting light homogeneously in its entire second sub-part. All the light rays extracted from a second sub-part, for example extracted from the second sub-part 212.4, pass through the same number of second sub-parts of other guide strips, and therefore, at a given moment, when a single light source is activated, a homogeneous display is enabled by the light module 100. Advantageously, the powers of the light sources 130.1 to 130.6 can be chosen so as to make a dynamic pattern obtained by successive activation of the light sources 130.1 to 130.6 homogeneous. For this purpose, the powers of the light sources 130.1 to 130.6 can be determined, from:

• Respective areas of the second sub-parts 212.1 to 212.6;
• Transparency levels of the second subparts 212.1 to 212.6, which make it possible to determine the loss of luminous intensity induced when light rays extracted from a second subpart pass through another subpart.

There presents a light module 100 according to a third embodiment.

• Un premier guide de lumière 110.1 comprenant des bandes de guidage 120.1 à 120.6 conformément à la description du premier mode de réalisation;
• Un premier ensemble de sources de lumière 130.1 à 130.6 aptes à injecter sélectivement de la lumière dans les bandes de guidage du premier guide de lumière 110.1;
• Un deuxième guide de lumière 110.2 comprenant des bandes de guidage 120.7 à 120.12, par exemple le même nombre de bande de guidage que le premier guide de lumière 110.1, conforme au premier mode de réalisation, mais dans lequel le pliage des bandes de guidage est dans un sens opposé au sens de pliage du premier guide de lumière 110.1;
• Un deuxième ensemble de sources de lumière 130.7 à 130.12 aptes à injecter sélectivement de la lumière dans les bandes de guidage du deuxième guide de lumière 110.2;
• Un élément de contrôle 150 apte à contrôler le premier ensemble de sources de lumière 130.1 à 130.6 et le deuxième ensemble de sources de lumière 130.7 à 130.12.

In the third embodiment, the light module 100 comprises:

• A first light guide 110.1 comprising guide strips 120.1 to 120.6 in accordance with the description of the first embodiment;
• A first set of light sources 130.1 to 130.6 capable of selectively injecting light into the guide strips of the first light guide 110.1;
• A second light guide 110.2 comprising guide strips 120.7 to 120.12, for example the same number of guide strips as the first light guide 110.1, according to the first embodiment, but in which the folding of the guide strips is in a direction opposite to the folding direction of the first light guide 110.1;
• A second set of light sources 130.7 to 130.12 capable of selectively injecting light into the guide strips of the second light guide 110.2;
• A control element 150 capable of controlling the first set of light sources 130.1 to 130.6 and the second set of light sources 130.7 to 130.12.

According to the third embodiment, the second sub-parts 212.7 to 212.12 of the second light guide 110.2 are positioned in the extension of the second sub-parts 212.1 to 212.6 of the first light guide 110.1. Preferably, a slice of the longest second sub-part 212.6 of the first light guide 110.1 is opposite, or even is attached to, a slice of the longest second sub-part 212.12 of the second light guide 110.2.

There illustrates a system for manufacturing a light guide of a light module 100 according to embodiments of the invention.

The system 600 is capable of manufacturing a series of light guides from a roll of material 620, of the same material and the same thickness as the flexible film 111 previously described. The roll of material 620 can furthermore be covered with a layer of glue, made of silicone or acrylic, not shown in the . The light guides obtained by the system 600 are in accordance with the light guide 110 illustrated in the , that is, before the guide strips are bent to obtain the light module 100 according to FIGS. 3 to 5.

The system 600 comprises for this purpose a belt 601 on which the roll of material 620 is arranged, the belt being driven in translation by a first drive device 602.

The system further comprises at least one device capable of forming microstructures in a first portion of the roll of material 620 corresponding to a first light guide, such as the light guide 110 illustrated with reference to the .

The device may in particular form microstructures in the first portion at positions corresponding to the second sub-portions 212.1 to 212.6, the microstructures being formed according to the predefined light pattern for each of the second sub-portions 212.1 to 212. No restriction is attached to the manner in which the microstructures are formed in the first portion. Examples of microstructure formation techniques have been given previously. The manufacturing method is described within the framework of a given technique for illustrative purposes only.

• un masque 611, comprenant un ensemble de picots répartis en fonction des motifs à réaliser sur chacun des guides de lumière produits en série. Les picots sont aptes à percer la couche de colle qui recouvre le rouleau 620 à des positions données, déterminées en fonction des motifs des deuxièmes sous-parties 212.1 à 212.6. Ainsi, le masque 611 est dédié à la fabrication de guides de lumière 110 tels que précédemment décrits en référence aux figures 1 et 2. Le masque 611 est en circuit fermé et a ainsi une longueur donnée. Le masque 611 est agencé sur un deuxième dispositif d’entraînement 612. Le premier dispositif d’entraînement 602 et le deuxième dispositif d’entraînement 612 sont agencés de manière à exercer une pression mécanique entre le masque 611 et une partie du rouleau 620. La pression mécanique est telle que les picots du masque 611 percent certaines positions de la partie du rouleau 620.
• - un dispositif d’irradiation UV 630 du système 600 apte à soumettre la première partie à laquelle le masque a été appliqué, à une irradiation UV.

According to this technique, the device capable of forming the microstructures comprises:

• a mask 611, comprising a set of pins distributed according to the patterns to be produced on each of the mass-produced light guides. The pins are capable of piercing the layer of glue which covers the roller 620 at given positions, determined according to the patterns of the second sub-parts 212.1 to 212.6. Thus, the mask 611 is dedicated to the manufacture of light guides 110 as previously described with reference to FIGS. 1 and 2. The mask 611 is in a closed circuit and thus has a given length. The mask 611 is arranged on a second drive device 612. The first drive device 602 and the second drive device 612 are arranged so as to exert mechanical pressure between the mask 611 and a portion of the roller 620. The mechanical pressure is such that the pins of the mask 611 pierce certain positions of the portion of the roller 620.
• - a UV irradiation device 630 of the system 600 capable of subjecting the first part to which the mask has been applied to UV irradiation.

The microstructures 113 previously described are thus formed at the positions defined by the pins of the mask 611. The microstructures are formed, according to the predefined patterns, in the second sub-parts 212.1 to 212.6 of the light guide 110 shown in the .

Other techniques for forming the microstructures may be provided, as described above. In particular, other roll-to-roll techniques may be used to form the microstructures.

• séparer la première portion du rouleau de matériau 620 du reste du rouleau de matériau 620, de manière à former le premier guide de lumière 110;
• découper les bandes de guidage 120.1 à 120.6, par une découpe selon l’axe X, tel que décrit précédemment en référence à la .

The system 600 further comprises at least one cutting device 640 capable of:

• separating the first portion of the material roll 620 from the remainder of the material roll 620, so as to form the first light guide 110;
• cutting the guide strips 120.1 to 120.6, by cutting along the X axis, as described previously with reference to the .

There is a diagram illustrating the steps of a method of manufacturing a light module 100 according to embodiments of the invention.

In a step 700, the material roll 620 is placed on the first drive device 602.

In a step 701, the first drive device 602 translates the roll of material towards the second drive device 612 on which the mask 612 is installed. More generally, step 701 is a step of translating the roll of material 620 so that a first portion of the roll is treated by at least one device capable of forming microstructures.

At a step 702, the drive devices 602 and 612 compress the mask 611 onto the first portion of the material roll 620.

At a step 703, the first portion of material on which the mask has been applied is irradiated by the UV irradiation device 630.

More generally, steps 702 and 703 are a step of forming microstructures in the first portion of the roll of material 620, such formation possibly involving techniques other than the application of a mask and UV irradiation, as previously explained. According to the invention, the microstructures are formed so as to produce several light patterns in distinct bands of positions of the first portion. The mask is predefined according to the size, the number, the position and the light pattern to be produced in the second sub-portions 212.1 to 212.6 as shown in FIG. .

At a step 704, the first portion is separated by the cutting device 640 from the remainder of the roll of material.

At a step 705, the guide strips 120.1 to 120.6 are cut, by cutting along the X axis, as previously explained.

In a step 706, the guide strips 120.1 to 120.6 thus cut are folded between the first part and the second part, in a direction perpendicular to the first part, so that the second parts of the guide strips overlap at least partially, as illustrated in FIGS. 3 to 5 previously described.

At a step 707, light sources 130.1 to 130.6 may be arranged opposite the light injection edge of the light guide 110.

A light module 100 is thus obtained according to embodiments of the invention. Such a light module can be integrated into equipment, for example in exterior or interior equipment of a motor vehicle.

According to embodiments, the method may further comprise, between steps 704 and 705, following the formation of microstructures, adding at least one layer of glue to at least a portion of the first portion, and preferably two layers of glue, one above and one below the portion of the portion of the first portion.

The part in which the glue layer is added may advantageously correspond to the second part of the guide strips. Advantageously, the method may further comprise the addition of a protective layer, which may be made of PC or another material, on each glue layer, by lamination.

The present invention is not limited to the embodiments described above as examples; it extends to other variants.

Claims (12)

Light module (100) comprising at least one light guide (110; 110.1; 110.2) of an at least partially transparent and flexible material, said light guide comprising at least two guide strips (120.1-120.6; 120.7-120.12), each guide strip comprising a first part (200) and a second part (210);
in which the first parts of the guide strips of a light guide are arranged next to each other,
wherein the second portions of the guide strips of a light guide are bent in a direction substantially normal to the first portions such that the second portions of the guide strips at least partially overlap;
wherein each second guide strip portion of a light guide comprises a first sub-portion (211.1-211.6) and a second sub-portion (212.1-212.6; 212.7-212.12), wherein the first sub-portion is adapted to guide light rays from the first guide strip portion to the second sub-portion, and wherein the second sub-portion is adapted to extract light in a predefined pattern;
wherein the light module further comprises a light source (130.1-130.6; 130.7-130.12) associated with each guide strip of a light guide, each light source associated with a guide strip being capable of injecting light rays into the first part of the guide strip. Light module according to claim 1, in which each light guide (110; 110.1; 110.2) has a thickness of between 12 and 1000 micrometers, in particular between 25 and 1000 micrometers, in particular between 50 and 500 micrometers, in particular between 50 and 125 micrometers. Light module according to claim 3, in which each light source (130.1-130.6; 130.7-130.12) is of the MicroLED or MiniLED type, with at least one dimension of the light source less than 1000 micrometers, in particular less than 500 micrometers, in particular less than 125 micrometers. Light module according to the preceding claims, wherein the second sub-parts (212.1-212.6; 212.7-212.12) have different lengths from each other. A light module according to claim 4, wherein the second sub-portion (212.1; 212.7) of the guide strip having the longest first sub-portion is shorter than the second sub-portion (212.6; 212.12) of the guide strip having the shortest first sub-portion. Light module according to claim 4 or 5, wherein the second outermost sub-portion of the light guide is the second shortest sub-portion (212.1; 212.7). Light module according to claim 4 or 5, wherein the second outermost sub-portion of the light guide is the second longest sub-portion (212.6; 212.12). Light module according to one of claims 4 to 7, in which each second sub-part (212.1-212.6; 212.7-212.12) of a guide strip (110; 110.1; 110.2) is capable of extracting light homogeneously over the entire second sub-part. Light module according to one of claims 4 to 7, in which each second sub-part (212.1-212.6; 212.7-212.12) is capable of extracting light in a given zone (212.1; 220.2-220.6) of the second sub-part, and in which the given zones of the second sub-parts of a light guide do not overlap. Light module according to one of the preceding claims, comprising a first light guide (110.1) and a second light guide (110.2), a first set of light sources (130.1-130.6) and a second set of light sources (130.7-130.8),
wherein the first light guide comprises at least two first guide strips (120.1-120.6) and the second light guide comprises at least two second guide strips (120.7-120.12);
wherein the second portions (212.1-212.6) of the first guide strips of the first light guide are bent in a direction substantially normal to the first portions, in a first sense, such that the second portions of the first guide strips at least partially overlap;
wherein the second portions (212.7-212.12) of the second guide strips of the second light guide are bent in a direction substantially normal to the first portions, in a second direction opposite to the first direction, such that the second portions of the second guide strips at least partially overlap.
wherein the first light guide and the second light guide are arranged such that a slice of the second longest sub-portion of the first guide strips faces a slice of the second longest sub-portion of the second guide strips. Light module according to one of the preceding claims, in which each light guide (110; 110.1; 110.2) comprises a film made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, polyethylene terephthalate, PET, or silicone. Method of manufacturing a light module (100) according to one of the preceding claims, comprising the following steps:

• positioning (700) a roll of material (620) on a belt driven by a drive device (602), said material being capable of guiding light rays by total internal reflection;
• translating (701) said roller so as to process a first portion of the roll of material;
• forming (702;703) microstructures in the first portion of the roll of material, so as to form light extraction zones distributed according to predetermined patterns in bands of positions of the first portion;
• cutting (704) the first portion so as to separate the first portion from the remainder of the roll of material;
• cutting (705) the first portion into a plurality of guide strips (120.1-120.6) corresponding to the position strips of the first portion, the guide strips comprising a first portion (200) and a second portion (210) extending longitudinally, the cutting of the guide strips separating at least the second portions of the guide strips;
• folding (706) the second portions of the guide strips in a direction normal to the first portions, such that the second portions of the guide strips at least partially overlap;
• arrangement (707) of light sources such that each light source is capable of injecting light into the first portion of each guide strip;

wherein each second guide strip portion comprises a first sub-portion (211.1-211.6) and a second sub-portion (212.1-212.6a), the first sub-portion being adapted to guide light rays from the first guide strip portion to the second sub-portion, and wherein the microstructures are formed in the second sub-portion so as to extract light into the second sub-portion according to one of the predetermined patterns.