Light module comprising a flexible film with dual light injections

Abstract

The present invention relates to a light guide (105) comprising: a flexible guide sheet (110) capable of emitting light received from a first injection channel (114a) and a second injection channel (114b); a first assembly (120a) comprising several first elements (120.1a1; 120.1a10) capable of injecting light rays into the first injection channel at different respective positions; a second injection assembly (120b) comprising several second elements (120.1b1; 120.1b10), each second element being capable of injecting light rays into the second channel at different respective positions. The first and second elements have different sizes such that, by folding a portion of the first injection elements, the first and second injection elements are stacked. The folding direction of the first elements is opposite to the folding direction of the second elements. Fig. 6

Description

Title of the invention: Light module comprising a flexible film with double light injections

[0001] The present invention relates to the field of light guide light modules, in particular light modules with a flexible light guide.

[0002] It is now common to implement lighting functions in all types of equipment, particularly in equipment for motor vehicles, for lighting purposes, information signaling, for aesthetic purposes of personalization or creating an atmosphere.

[0003] It is known to use screens, such as LCD screens.

[0004] However, such technology is not only expensive but also sensitive to environmental conditions such as temperature, humidity or UV radiation. It is therefore inappropriate for many devices having uses that induce a variation in environmental conditions, as may be the case for devices used outdoors.

[0005] What is more, it is preferable to have a flexible and lightweight display or light module in order to facilitate its integration into any type of equipment.

[0006] Furthermore, the aforementioned solution has the disadvantage of high energy consumption, which is all the more important as the surface area of ​​the equipment in which it is desired to integrate a light module is large.

[0007] It is known to use light modules with a light guide comprising a flexible film in which light rays are guided, which are returned according to a given pattern, depending on microstructures etched in the film. The injection of light is carried out in one or more injection slices of the flexible film by a group of injection elements of the light guide.

[0008] In order to facilitate the manufacture of the light guide, the light guides can be mass-produced, using a roll-to-roll manufacturing procedure.

[0009] A roll of film is gradually unwound in a machine carrying out the following steps, so that each part of the roll is subjected to the following steps: - formation of microstructures in the film according to a light pattern of the light guide to be produced, for example by mechanical compression of a mask against the part, the mask comprising pins, the pins being arranged according to the light pattern of the light guide to be produced, then UV irradiation of the part after pressure of the mask, the microstructures being thus formed at the places indented by the spikes of the mask; - cutting the light guide in the part of the roll so that the light guide comprises a flexible film in which the micro structures are formed, as well as injection elements integral with a slice of the flexible film.

[0010] The injection elements are generally cut to different lengths so as to be folded and then superimposed to facilitate injection into an injection surface by a light source.

[0011] Such cutting into different lengths with roll-to-roll manufacturing results in significant loss of roll material.

[0012] Such a loss is all the more significant when high-intensity light guides are required.

[0013] Indeed, to increase the light intensity of the pattern projected by the flexible film light guide, two groups of injection elements can be provided on either side of the flexible film. Specifically, the two groups of injection elements are arranged symmetrically by mirror relative to the central axis of the light guide sheet. In this configuration, the injection elements having the same length in each group are positioned at the same level on the respective light injection edge. This configuration thus induces losses of the flexible material from which the light guide is made.

[0014] There is thus a need to have a flexible, robust, low-energy-consumption light module that can be easily manufactured using a roll-to-roll process with the least possible loss of materials during manufacturing.

[0015] The present invention improves the situation.

[0016] A first aspect of the invention relates to a light guide comprising: - a flexible guide sheet, the flexible guide sheet being capable of receiving light rays by at least a first light injection edge and a second light injection edge of said flexible guide sheet, and of returning the light rays in a direction substantially normal to the flexible guide sheet, in which the first injection edge and the second injection edge are on either side of the flexible guide sheet; - at least one first injection assembly comprising several first injection elements, each first injection element being capable of receiving light rays via a first end and of injecting said light rays into the first injection section of the flexible guide sheet via a second end, in which the second ends are positioned at respective positions different from the first section injection; - at least one second injection assembly comprising several second injection elements, each second injection element being capable of receiving light rays via a first end and of injecting said light rays into the second injection section of the flexible guide sheet via a second end, in which the second ends are positioned at respective positions different from the second injection section.

[0017] The first injection elements and the second injection elements are flexible and are made of a single piece with a flexible film of the flexible guide sheet, the first injection elements have different sizes so that, by folding a portion of the first injection elements along an axis substantially parallel to the first injection edge in a first folding direction, the first injection elements are partially stacked and the first ends of the first injection elements form a light-receiving surface of the first assembly.The second injection elements have different lengths such that, by folding a portion of the second injection elements along an axis substantially parallel to the second injection edge in a second folding direction, the second injection elements are partially stacked and the first ends of the second injection elements form a light receiving surface of the second assembly. The first folding direction is opposite to the second folding direction.

[0018] Thus, the light guide according to the invention can be produced by a roll-to-roll manufacturing method, with minimized loss of material, due to the inversion between the first injection assembly and the second injection assembly. Indeed, during mass production from a roll of material, the first injection assembly of a first light guide has a shape at least partially complementary to the second injection assembly of a second light guide, which limits material waste, and therefore losses.

[0019] According to embodiments, the second end of the first longest injection element may be opposite the second end of the second shortest injection element, and the second end of the first shortest injection element may be opposite the second end of the second longest injection element.

[0020] Thus, the first and second injection assemblies occupy positions facing each other on the first and second injection slices. The shape complementarity between two light guides manufactured successively by a roll-to-roll process is improved, and material losses are reduced.

[0021] According to embodiments, the first set may comprise as many first injection elements as the second set comprises second injection elements.

[0022] Thus, the shape complementarity between two light guides manufactured successively by a roll-to-roll process is improved, and material losses are reduced.

[0023] Additionally, each second end of a first injection element of the first set may face a second end of a second element of the second set, forming pairs of first and second injection elements, and the sums of the respective lengths of the first and second injection elements of the pairs may be equal.

[0024] Material losses are thus minimized during the manufacture of several light guides by a roll-to-roll process.

[0025] According to embodiments, the flexible guide sheet may comprise a light emission zone capable of returning the light rays in the direction substantially normal to the flexible guide sheet, a first mixing zone between the light emission zone and the first injection slice, and a second mixing zone between the light emission zone and the second injection slice. The first mixing zone may be capable of mixing the light received at the different positions of the first injection slice and the second mixing zone may be capable of mixing the light received at the different positions of the second injection slice.

[0026] It is thus made possible to return light with high intensity and high surface homogeneity.

[0027] According to embodiments, the flexible film and the first and second injection elements may be made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, or polyethylene terephthalate, PET, and may have a thickness of between 25 and 1000 micrometers, in particular between 50 and 1000 micrometers, for example between 200 and 500 micrometers.

[0028] Thus, great flexibility of the light guide is allowed, which facilitates its integration into any type of equipment.

[0029] According to embodiments, the flexible film may comprise microstructures, for example etched by ultraviolet insolation, so as to return the light injected into the flexible guide sheet according to a given pattern.

[0030] Thus, it is made possible to produce various patterns.

[0031] A second aspect of the invention relates to a light module comprising a light guide according to the first aspect of the invention, at least one first light source arranged opposite the receiving surface of the first assembly injection and at least one second light source arranged opposite the receiving surface of the second injection assembly.

[0032] A third aspect of the invention relates to motor vehicle equipment comprising a light module according to the invention.

[0033] A fourth aspect of the invention relates to a method of manufacturing a light guide 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; - translation of the roll of material so as to process a first part of the roll of material; - formation of microstructures in the first part of the roll of material, the microstructures being formed according to a predetermined light pattern; - cutting the first part so as to separate the first part from the rest of the roll of material; - cutting the first elements of the first injection assembly and the second elements of the second injection assembly.

[0034] A fifth aspect of the invention relates to a system for manufacturing a light guide according to the first aspect of the invention, comprising: - a drive device capable of translating a belt capable of supporting the roll of material; - at least one device capable of forming microstructures in a first part of the roll of material translated by the drive device, the microstructures being formed according to a predetermined light pattern; - a cutting device capable of separating the first part from the rest of the roll of material and of cutting the first elements of the first injection assembly and the second elements of the second injection assembly.

[0035] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings in which:

[0036] [Fig-1] illustrates a sectional view of elements of a light guide for a light module according to embodiments of the invention;

[0037] [Fig.2] illustrates a partial and front view of the elements of a light guide for a light module according to embodiments of the invention;

[0038] [Fig.3] illustrates a partial and front view of the elements of a light guide for a light module according to embodiments of the invention;

[0039] [Fig.4] illustrates a three-dimensional view of a light guide injection assembly for a light module according to embodiments of the invention;

[0040] [Fig.5] illustrates a front view of a light guide injection assembly for light module according to embodiments of the invention;

[0041] [Fig.6] illustrates a front view of a light guide for a light module according to embodiments of the invention;

[0042] [Fig.7] illustrates a front view of the light guide according to [Fig.6];

[0043] [Fig.8] illustrates a system for manufacturing a series of light guides for light module according to embodiments of the invention;

[0044] [Fig.9] illustrates a series of light guides produced by the manufacturing system according to embodiments of the invention;

[0045] [Fig. 10] illustrates the steps of a method of manufacturing a light guide for a light module according to embodiments of the invention.

[0046] The description focuses on the features that distinguish the light module and the light guide from those known in the state of the art.

[0047] [Fig.l] shows elements of a light guide 105 of a light module according to embodiments of the invention.

[0048] The light guide 105 comprises a flexible guide sheet 110 capable of receiving light rays via at least two light injection slices 114 and of returning the light rays in a Z direction substantially normal to a surface of the flexible guide sheet which thus extends in an XY plane in [Fig.l]. A single injection slice is shown in [Fig.l], to simplify the description.

[0049] A guide sheet is understood to mean an optical guide element one of whose dimensions is much smaller than the other two dimensions in space, for example one or more orders of magnitude smaller. As illustrated in [Fig. 1], a flexible guide sheet 110 is considered here whose thickness along the Z axis is at least two orders of magnitude smaller than its dimensions along the XY plane in which the flexible guide sheet 110 extends.

[0050] The flexible guide sheet 110 may comprise a flexible film 111 at its core comprising the light injection edge 114, being capable of guiding the light rays in a global direction X, and comprising a set of micro structures 113 capable of returning the light rays guided in the flexible film 111 outside the flexible guide sheet 110, in particular in one or more directions substantially along the Z axis.

[0051] The flexible film 111 may be a substrate film made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, or polyethylene terephthalate, PET. The flexible film 111 may have a thickness, i.e. a dimension along the Z axis, of between 12 and 1000 micrometers. More precisely, the thickness of the flexible film 111 may be between 25 and 1000 micrometers, in particular between 50 and 1000 micrometers, for example between 200 and 500 micrometers. Alternatively, it is the flexible guide sheet 110 which has a thickness of between 200 and 1000 micrometers.

[0052] The aforementioned materials, combined with a low thickness as described above, make it possible to obtain a flexible and transparent film 111. Other materials may be provided for the composition of the flexible film 111. However, it is preferable according to the invention to provide deformable and transparent materials.

[0053] A thin coating of microstructures 113 may be etched onto one of the faces of the flexible film 111, or into the flexible film 111.

[0054] 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.

[0055] 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.

[0056] No restriction is attached to the manner in which 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.

[0057] 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 by shape complementarity.

[0058] As a further variant, 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 removing material. In this case, the microstructures are holes or gaps. Optionally and additionally, additional surface or volume elements, prismatic, reflective, diffracting or diffusing, can be added in the holes or gaps to form the microstructures 113.

[0059] 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 from 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.

[0060] Alternatively or in a complementary manner, the microstructures 113 are elements exogenous to the film added to the face of the film 111.

[0061] The microstructure coating 113 may in particular have a thickness along the Z axis of less than 20 micrometers.

[0062] Advantageously, the microstructures 113 can be distributed along the X axis so that a density of microstructures 113 is an increasing function of the distance from the light injection edge 114 through which the light rays injected by an injection element 120 are received. In other words, the further the microstructures 113 are from the light injection edge 114, the more densely they are grouped. Such a distribution advantageously makes it possible to ensure a homogeneous distribution along the X axis of the light intensity of the pattern emitted by the flexible guide sheet 110.

[0063] The term “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 the light over the entire flexible guide sheet. The pattern may also be a two-dimensional shape or symbol obtained by contrast between the light intensities of different positions in the XY plane of the flexible guide sheet 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.

[0064] 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 flexible 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 flexible film against UV rays, once the microstructures 113 have been etched. Without such UV protection, the pattern projected by the flexible guide sheet 110 is likely to degrade over time, in particular when exposed to sunlight.

[0065] The flexible film 111 and the protective layers 112.1 and 112.2 are shown in spaced apart in [Fig.l], for illustrative purposes only. It will be understood, however, that the protective layers 112.1 and 112.2 may be attached to the flexible film, in particular by lamination.

[0066] The propagation of the light rays in the flexible film 111 is done by total internal reflection thanks to the difference between the refractive index of the flexible film 111 and that of a layer of glue or adhesive applied to at least one face of the flexible film.

[0067] The assembly of the flexible 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 flexible film 111 and each protective layer 112.1 and 112.2, and this on both sides of the flexible film to adhere the protective layers to the flexible film.

[0068] The chosen glue is transparent and has a refractive index different from that of the flexible film so as to allow total internal reflection in the flexible film 111. In other words, due to the difference in refractive index, the light rays propagating in the flexible film undergo total reflection when they encounter the interface between the flexible film 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.

[0069] The guide sheet 110 being 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.

[0070] The light guide 105 illustrated in [Fig.l] also comprises an injection assembly 120 comprising several light injection elements, comprising several injection elements described with reference to the following figures, the assembly 120 being capable of distributing the light in the flexible guide sheet 110 at different positions along the Y axis, along the light injection edge 114. The light is injected, at each position along the Y axis, in a direction substantially parallel to the X axis.

[0071] The injection assembly 120 comprises an inlet surface 121 of rectangular or square section in [Fig.l]. However, the assembly 120 may have an inlet surface having a different shaped section.

[0072] In [Fig.l], the injection assembly 120 is shown with an outlet surface 122 extending in the Y direction and placed opposite the light injection edge 114. It will be understood from reading the description of the following figures that the outlet surface 122 and the light injection edge 114 are merged, the flexible film 111 and the injection assembly 120 forming a single piece.

[0073] The injection assembly 120 further comprises the inlet surface 121, at a end of the injection assembly 120, capable of receiving light rays from a light source external to the light guide 105 and not shown in [Fig.l], and the injection assembly 120 is capable of guiding the light longitudinally along the Y axis by distributing it on the exit surface 122. The distribution of light by the exit surface 122 will be better understood in the light of the description of the following figures.

[0074] [Fig. 2] shows elements of a light module 100 comprising a light guide 105 with a set 120 of injection elements and a flexible guide sheet 110, and a light source 130.

[0075] Depending on the distribution of the microstructures 113, the flexible guide sheet 110, or more precisely the flexible film 111, may comprise a mixing zone 111.2 and a light emission zone 111.1 provided with the microstructures 113. The mixing zone 111.2 is arranged upstream of the light emission zone according to the direction of propagation of the light rays. The light emission zone 111.1 is integrated into a region 1110.

[0076] The light injected into the light guide sheet 110 via the injection edge 114 is mixed in the mixing zone 111.2 in order to obtain better light homogeneity. The light then propagates into the light emission zone 111.1 through which the light emerges from the light guide sheet 110 in the Z direction.

[0077] More generally, the mixing zone 111.2 is an area of ​​the flexible guide sheet not comprising the light pattern emitted by the flexible guide sheet 110, the mixing function of the zone 111.2 being optional.

[0078] The set 120 of injection elements 120.1 is capable of injecting light rays from the source 130 into the injection edge 114 towards the mixing zone 111.2. In [Fig.2], a single injection assembly 120 is shown. However, according to the invention, the light module 100 according to the invention comprises at least one injection assembly 120 on either side of the flexible guide sheet, so as to increase the light intensity of the pattern etched in the light emission zone 111.1. Thus, with reference to [Fig.2], the light module 100 according to the invention also comprises at least one injection assembly 120 to the right of the flexible guide sheet 110, not shown in [Fig.2] but illustrated and described later.

[0079] Note that the light guide 105 may comprise several injection assemblies 120 per injection slice 114, each assembly being arranged at a given set of Y positions of the injection slice 114. Each injection assembly 120 is thus configured to illuminate a different region 1110 in the light guide sheet. In the following, a single injection assembly 120 per slice injection 114 is considered, for illustrative purposes.

[0080] The assembly 120 comprises several light injection elements 120.1. The assembly 120 may in particular comprise between three and ten injection elements 120.1. In the non-limiting example of [Fig.2], the light guide 105 comprises an assembly 120 with ten injection elements. For reasons of clarity, only two light injection elements 120.1 have been referenced.

[0081] The assembly 120 is coupled with at least one light source 130 so as to receive the light rays R emitted by said light source in each of the light injection elements 121.

[0082] Given that the light injection elements 121 are obtained by cutting from the same material as the flexible film 111, the light rays R will propagate by total internal reflection in the light injection elements 120.1 so as to bring light to the light guide sheet which is adjacent and integral with the light injection elements 120.1, and the light will thus illuminate the region(s) 1110 of the light guide sheet 110.

[0083] The superposition of the light injection elements 120.1 forming the assembly 120 can thus be a coupling bar, or light bar, configured to receive the light rays coming from the light source 130 and propagate them in the light guide sheet 110. The assembly 120 can be of square or rectangular section.

[0084] No restriction is attached to the light source 130, which may be any light source technology. For example, the light source 130 may be an electroluminescent element, such as an LED for example, mounted on a substrate 131. A heat dissipation element 132 may furthermore be arranged below the substrate 131.

[0085] The light source 130 may be capable of generating light in a range of wavelengths. Such an interval may be centered around a visible color, in order to generate colored light, for example blue, red or green. Alternatively, the light source 130 may emit light rays over the entire range of wavelengths visible to the human eye, so as to generate white light. The light source 130 may be controlled by a control element not shown. Alternatively, the light source 130 is not arranged directly opposite an input surface 121 of the injection element 120, but the light module 100 further comprises an optical fiber placed between the source 130 and the injection assembly 120, which makes it possible to offset the source 130 relative to the light guide 105.

[0086] It is thus made possible to inject light at different longitudinal positions along the Y axis of the injection slice 114.

[0087] As will be better understood from reading the description of the following figures, the Light guide 105 may be cut from a roll of the same material as flexible film 111 and injection members 120, the roll extending along the X axis and having the same width La as light guide 105.

[0088] As will be explained in the following, the references (pj) refer to injection positions of index j, each injection position of index j corresponding to an interval of positions along the injection axis Y in the injection slice 114, j varying between 1 and N, N being the number of injection elements 120.1 in the injection assembly 120 (i.e. N=10 in the example considered so far).

[0089] The light module 100 thus comprises the light guide 105, comprising the flexible guide sheet 110 and the injection assembly 120, and the light source 130.

[0090] A non-visible part 13 of the light module 100 may comprise the assembly 120 and the light source 130. Such a part may be hidden while the light emission zone is on the contrary visible from the outside of equipment comprising the light guide 105.

[0091] [Fig. 3] illustrates the light guide of [Fig. 2] with the light injection elements 120.1 of the injection assembly 120 being unfolded. In [Fig. 3], each injection element 120.1 has a respective length Lh and has a width W.

[0092] For the sake of clarity in [Fig. 3], only the length Lh and the width W of the longest injection element 120 have been referenced. The lengths Lh of the other injection elements 120 are less than the length Lh of the longest injection element. On the other hand, the widths W of all the injection elements 120.1 may be equal.

[0093] By way of non-limiting example, the length Lh of the longest injection element 120.1 is between 100 and 500 millimeters. Similarly, the width W can be between 1 and 20 mm.

[0094] A folding position 300 is furthermore indicated in [Fig. 3], each injection element 120.1 being able to be folded into the folding position 300 so that the injection elements 120.1 are superimposed to form the assembly 120. The respective lengths Lh of the injection elements are determined from the folding position and the respective Y positions of the injection elements, so that their ends together form the injection surface 121.

[0095] [Fig.4] illustrates a three-dimensional view of the assembly 120 and the light source 130, of a light module 100 according to embodiments of the invention.

[0096] As illustrated in [Fig. 4], each light injection element 120.1 has a thickness e. The thickness e corresponds to the thickness of the light guide 105, i.e. the flexible film 111. The light injection element 120.1 comprises two ends 120.10, one of which, illustrated in [Fig. 2], is secured to the flexible guide sheet 110 and the other, illustrated in [Fig. 4], is able to be opposite the light source 130. The light rays emitted by the light source 130 enter through one end 120.10, called the first end, and are transmitted to the other end 120.10, called the second end, then to the light guide sheet 110 via the light injection edge 114, which coincides with the second ends 120.10 of the injection elements 120.1.

[0097] It should be noted that during the manufacturing process of the light guide 105, detailed later, the injection elements 120.1 and the light guide sheet 110 are manufactured from a roll of material, engraved according to a given pattern, then cut or sheared, to separate the light guide 105 from the rest of the roll, and to separate the different injection elements 120.1 along the X axis and thus form the different injection elements 120.1 before folding according to the folding position 300.

[0098] Thus, the light injection elements 120.1 remain attached to the guide sheet 110 on their second ends 120.10.

[0099] The respective lengths Lh of the injection elements 120.1 are such that the first ends 120.10 facing the light source 130 coincide to form the injection surface 121 of the assembly.

[0100] The injection surface 121 thus has a thickness E equal to the sum of the thicknesses e of the injection elements 120.1.

[0101] [Fig.5] illustrates the injection assembly 120 for a light module according to embodiments of the invention.

[0102] In [Fig.5], the injection elements 120.1 are in the folded position and are composed of: - a main part 120.12 which extends along the X axis corresponding to a light injection direction, perpendicular to the injection edge 114; and - an end portion 120.13 which extends along the Y axis, substantially parallel to the injection section 114.

[0103] For each injection element 120.1, the two parts 120.12 and 120.13 are connected by a fold 120.14 positioned at the fold position 300 illustrated previously. The end part 120.13 extends after the fold 120.14. In a non-limiting embodiment, the fold 120.14 is a right-angled fold.

[0104] The length Lh of an injection element 120 is thus the sum of the length of the main part 120.12 and of the terminal part 120.13.

[0105] As illustrated in [Fig.4], the injection elements 120.1 of an assembly 120 are folded so that their end portions 120.13 form a stack 123 of thickness E, adapted to an emission surface of the light source 130.

[0106] The light rays R from the light source 130 enter through the entry surface 121 and propagate in the different injection elements 120.1. The rays luminous R are totally reflected inside the light injection elements 120.1 and are redirected via the folds 120.14 towards the guide sheet 110.

[0107] [Fig.6] illustrates a light guide 105 of a light module according to an embodiment of the invention.

[0108] As mentioned previously, in order to increase the brightness of the pattern projected in the light emission zone 111.1, two injection assemblies 120a and 120b can be provided, so as to inject light rays into two distinct slices 114a and 114b of the guide sheet 110. According to the invention, the injection slices 114a and 114b are on either side of the guide sheet 110.

[0109] The description of the injection assembly 120 presented with reference to FIGS. 1 to 5 applies to the first injection assembly 120a and to the second injection assembly 120b. The first injection assembly 120a may comprise N1 injection elements 120.1 and the second injection assembly 120b may comprise N2 injection elements 120.1, N1 and N2 being two integers greater than or equal to 2. Preferably, N1 and N2 are equal.

[0110] In the example given for illustrative purposes in [Fig.6], NI and N2 are equal to 10.

[0111] [Fig.6] shows the injection assemblies 120a and 120b before they are folded so as to produce the stack 123 described previously and to form the entry surface 121 described previously.

[0112] According to the invention, the lengths Lh of the injection elements of the first injection assembly 120a are such that they allow folding of the first assembly in a first folding direction, and the lengths Lh of the injection elements of the second injection assembly 120a are such that they allow folding of the second assembly in a second folding direction, opposite to the first folding direction.

[0113] In order to allow such folding, and in accordance with the description given previously of the injection assembly 120: - the first injection assembly 120a may comprise an injection element 120.lal whose length Lh is the greatest of the first assembly 120a and an injection element 120.1al0 whose length Lh is the smallest of the first assembly 120a, the length Lh of the injection elements 120.1a decreasing between the injection element 120.lal and the injection element 120.1al0; and - the second injection assembly 120b may comprise an injection element 120.1bl whose length Lh is the smallest of the second assembly 120b and an injection element 120.1bl0 whose length Lh is the largest of the second assembly 120b, the length Lh of the injection elements 120.1b increasing between the injection element 120.1bl and the injection element 120.1bl0.

[0114] Preferably, the shortest injection element 120.110 of the first set 120a is opposite the longest injection element 120.110 of the second set 120b.

[0115] In other words, the injection element 120.1110 corresponds to a set of injection positions in Y corresponding at least partially to a set of injection positions in Y of the injection element 120.1110.

[0116] Similarly, the longest injection element 120.1al of the first set 120a is opposite the shortest injection element 120.1bl of the second set 120b.

[0117] In other words, the injection element 120.1al corresponds to a set of injection positions in Y corresponding at least partially to a set of injection positions in Y of the injection element 120.1bl0.

[0118] In the example illustrated in [Fig.6], NI is equal to N2, and for each injection element of index i of the first set 120a, i being between 1 and 10 (equal to NI and N2), the length Lh of the injection element of index i is equal to the length Lh of the injection element of index Nl-i (or N2-i) of the second set 120b. In other words, the second set 120b is obtained by central symmetry of the first set 120a with respect to the center of the guide sheet 110.

[0119] More generally, to minimize material losses during the manufacture of the light guide 105, the first assembly 120a and the second assembly 120b may be such that: - each injection element of the first set 120a is opposite an injection element of the second set 120b, thus forming a pair of injection elements; and - the sum of the lengths Lh of the injection elements of a pair is constant whatever the position in Y considered.

[0120] The guide sheet 110 can then comprise a light emission zone 111.1 as previously described, as well as a first non-etched zone 111.2a, or first mixing zone 111.2a, opposite the first injection edge 114a, and a second non-etched zone 111.2b, or second mixing zone 111.2b, opposite the second injection edge 114b.

[0121] [Fig.7] illustrates the light guide 105 of [Fig.6] with two injection assemblies 120a and 120b, when the injection members are folded, with respective light sources 130a and 130b.

[0122] The injection elements of the first set 120a are thus folded in a first direction along the Y direction, and the injection elements of the second set 120b are folded in a second direction along the Y direction, opposite to the first direction.

[0123] An input surface of the first assembly 120a is thus opposite a first light source 130a and an input surface of the second assembly 120b is opposite view of a second light source 130b.

[0124] [Fig.8] illustrates a system for manufacturing a light guide 105 for a light module 100 according to embodiments of the invention.

[0125] The system 800 is capable of manufacturing a series of light guides 105 from a roll of material 820, of the same material and the same thickness as the flexible film 111 previously described. The roll of material 820 can also be covered with a layer of glue, made of silicone or acrylic, not shown in [Fig.8].

[0126] The system 800 comprises for this purpose a belt 801 on which the roll of material 820 is arranged, the belt being driven in translation by a first drive device 802.

[0127] The system further comprises at least one device adapted to form microstructures in a first portion of the roll of material 820, the microstructures being formed according to a predetermined light pattern. 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 scope of a given technique for illustrative purposes only.

[0128] According to this technique, the device capable of forming the microstructures comprises: - a mask 811, comprising a set of pins distributed according to the pattern to be produced on the guide sheet 110 of each of the mass-produced light guides 105. The pins are capable of piercing the layer of glue which covers the roller 820 at given positions determined according to the pattern. Thus, the mask 811 is dedicated to the manufacture of light guides 105 producing a given light pattern. The mask 811 is in a closed circuit and thus has a given length. The mask 811 is arranged on a second drive device 812. The first drive device 802 and the second drive device 812 are arranged to exert mechanical pressure between the mask 811 and a portion of the roller 820. The mechanical pressure is such that the pins of the mask 811 pierce certain positions of the portion of the roller 820; - a UV irradiation device 830 of the system 800 capable of subjecting the first part to which the mask has been applied to UV irradiation.

[0129] The microstructures 113 previously described are thus formed at the positions defined by the pins of the mask 811. The microstructures are formed in the light emission zone 111.1 of the light guide 115.

[0130] The areas of the roller 820 corresponding to the areas 111.2a and 111.2b as well as to the first and second injection assemblies 120a and 120b are provided on the mask 811 which does not include any spikes in these areas, since they are not intended to reflect light rays.

[0131] 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.

[0132] The system 800 further comprises at least one cutting device 840 capable of cutting the oblique edges of each light guide 105, as will be better understood upon reading the description of [Fig.9], as well as the separations between the injection elements of each injection assembly 120a and 120b by cutting along the X axis.

[0133] [Fig.9] shows the roll of material 820 after application of the mask 811 on two parts of the roll 820 corresponding respectively to two light guides 105.1 and 105.2, before cutting by the cutting device 840.

[0134] A first portion of the roll 820 corresponds to a first light guide 105.1, to which the mask 811 has already been applied, and which has already undergone UV irradiation. The second portion of the roll 820 corresponds to a second light guide 105.2 to which the mask 811 is being applied.

[0135] As previously explained, the mask 811 corresponds to a circuit of a given size. When the mask 811 is completely unfolded, it has the size shown in [Fig.9]. The pins of the mask are included in the light emission zone 111.1 shown in [Fig. 1] so as to etch the light emission zone 111.1.

[0136] The remainder of the roller 820, located to the left of the second part, has not yet been in contact with the mask 811.

[0137] The mask 811 also comprises areas corresponding to the areas 811.2a and 811.2b previously described, not comprising any pins. In addition, the mask 811 comprises an area 900a without pins corresponding to the first injection assembly 120a of the second light guide 105.2, as well as an area 900b without pins corresponding to the second injection assembly 120b of the next light guide to which the mask will be applied.

[0138] Such a mask 811 allows the manufacture of light guides in series 811. In addition, due to the inversion between the first injection assembly 120a and the second injection assembly 120b, the losses of material from the roll 820 are reduced. When the first injection assembly 120a and the second injection assembly 120b have complementary shapes, as is the case for the corresponding zones 900a and 900b of the mask 811 in [Fig. 9], the manufacture of the light guides does not cause any loss or very little loss of material from the roll 820.

[0139] It should be noted that the mask 811 generally has a fixed size, which may be imposed by the dimensions of the second drive device 812 of [Fig.8]. The lengths referred to below are the dimensions along the X axis. However, it is desirable to maximize the length of the light emission zone 111.1, in order to maximize the efficiency associated with the use of the material of the roller 820. When the first and second injection assemblies are not reversed, the length of the light emission zone 111.1 is at most equal to the length of the mask 811, reduced by the lengths of the zones 111.2a and 111.2b as well as the sum of the two lengths Lh of the longest injection elements of the two injection assemblies 120a and 120b.

[0140] For example, when the mask has a length of 600 mm, the length Lh of the longest injection element of the first set 120a and the second set 120b is 150 mm, and the length of each zone 111.2a and 111.2b is 25 mm, the light emission zone 111 is at most equal to 250 mm.

[0141] Advantageously, when the first and second injection assemblies are reversed (as shown in FIGS. 6, 7 and 9), the length of the light emission zone 111.1 is at most equal to the length of the mask 811 reduced by the lengths of the zones 111.2a and 111.2b as well as the sum of the length Lh of the shortest injection element of one injection assembly and the length Lh of the longest injection element of the other injection assembly.

[0142] When the mask has a length of 600 mm, the length Lh of the longest injection element of the first set 120a or the second set 120b is 150 mm, the length Lh of the shortest element of the first set 120a or the second set 120b is 10 mm, and the length of each zone 111.2a and 111.2b is 25 mm, the light emission zone 111 is at most equal to 390 mm, i.e. an increase of more than 50% compared to non-inverted injection assemblies.

[0143] Thus, the inversion of the injection assemblies 120a and 120b makes it possible to increase the size of the light emission zone 111.1, and therefore makes it possible to optimize the use of the material of the roller 820.

[0144] [Fig. 10] illustrates the steps of a method of manufacturing a light guide 105 for a light module according to embodiments of the invention.

[0145] In a step 1001, the roll of material 820 is placed on the first drive device 802.

[0146] In a step 1002, the first drive device 802 translates the roll of material towards the second drive device 812 on which the mask 812 is installed. More generally, step 1002 is a step of translating the roll of material 820 so that a first part of the roll is treated by at least one device capable of forming microstructures.

[0147] At a step 1003, the drive devices 802 and 812 compress the mask 811 on a first part of the roll of material 820.

[0148] In a step 1004, the first portion of material on which the mask has been applied is irradiated by the UV irradiation device 830.

[0149] More generally, steps 1003 and 1004 are a step of forming microstructures in the first portion of the roll of material 820, such formation possibly involving techniques other than the application of a mask and UV irradiation, as previously explained.

[0150] In a step 1005, the first part is separated by the cutting device 840 from the rest of the roll of material. Such separation is enabled by an oblique cut in accordance with the cutting plane 901.1 and 901.2 of [Fig.9], the oblique cut being determined from the respective lengths Lh and the respective arrangements of the injection elements of the first and second injection assemblies 120a and 120b.

[0151] In a step 1006, the injection elements of the first and second injection assemblies are separated by a cut along the X axis. A first light guide 105 according to the invention is thus obtained. Note that steps 1005 and 1006 can be carried out at the same time. Alternatively, step 1006 is implemented before step 1005.

[0152] It should also be noted that the translation step 1002 takes place continuously, that is to say that the mask is progressively compressed onto the first part as the translation progresses. Similarly, the UV irradiation can be carried out in a fixed position while the first part is translated below the UV irradiation device 830.

[0153] Steps 1002 to 1006 may be repeated on a second portion of the roll of material 820 in order to obtain a second light guide 105 identical to the first light guide.

[0154] The present invention is not limited to the embodiments described above as examples; it extends to other variants.

Claims

1. Claims Light guide (105) comprising: - a flexible guide sheet (110), the flexible guide sheet being capable of receiving light rays by at least a first light injection edge (114a) and a second light injection edge (114b) of said flexible guide sheet, and of returning the light rays in a direction substantially normal to the flexible guide sheet, in which the first injection edge and the second injection edge are on either side of the flexible guide sheet; - at least one first injection assembly (120a) comprising several first injection elements (120.1al; 120.1al0), each first injection element being capable of receiving light rays via a first end (120.10) and of injecting said light rays into the first injection section of the flexible guide sheet via a second end (120.10), in which the second ends are positioned at respective positions different from the first injection section; - at least one second injection assembly (120b) comprising several second injection elements (120.1bl; 120.1b 10), each second injection element being capable of receiving light rays via a first end and of injecting said light rays into the second injection section of the flexible guide sheet via a second end, in which the second ends are positioned at respective positions different from the second injection section; wherein the first injection elements and the second injection elements are flexible and are integral with a flexible film (111) of the flexible guide web; wherein the first injection elements have different sizes so that, by folding a portion of the first injection elements along an axis (300) substantially parallel to the first injection slice in a first folding direction, the first injection elements are partially stacked and the first ends of the first injection elements form a light receiving surface (121) of the first set; wherein the second injection elements have different lengths so that, by folding a portion of the second injection elements along an axis substantially parallel to the second injection slice in a second folding direction, the second injection elements are partially stacked and the first ends of the second injection elements form a light receiving surface (121) of the second set; wherein the first folding direction is opposite to the second folding direction.

2. The light guide of claim 1, wherein the second end (120.10) of the first longest injection element (120.1al) faces the second end of the second shortest injection element (120.1bl), and the second end of the first shortest injection element (120.1al0) faces the second end of the second longest injection element (120.1b 10).

3. A light guide according to claim 1 or 2, wherein the first injection assembly (120a) comprises as many first injection elements (120.lal; 120.1al0) as the second injection assembly (120b) comprises second injection elements (120.1bl; 120.1bl0).

4. A light guide according to claim 3, wherein each second end (120.10) of a first injection element of the first injection assembly (120a) faces a second end (120.10) of a second injection element of the second injection assembly (120b), forming pairs of first and second injection elements, wherein the sums of the respective lengths of the first and second injection elements of the pairs are equal.

5. Light guide according to one of claims 1 to 4, in which the flexible guide sheet (110) comprises a light emission zone (111.1) capable of returning the light rays in the direction substantially normal to the normal of the flexible guide sheet, a first mixing zone (111.2a) between the light emission zone and the first injection edge (114a), and a second mixing zone (111.2b) between the light emission zone and the second edge injection (114b); wherein the first mixing zone is capable of mixing the light received at the different positions of the first injection slice and wherein the second mixing zone is capable of mixing the light received at the different positions of the second injection slice.

6. Light guide according to one of the preceding claims, in which the flexible film (111) and the first and second injection elements (120.1 al; 120.1al0; 120.1bl; 120.IblO) are made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, or polyethylene terephthalate, PET, and have a thickness of between 50 and 1000 micrometers, for example between 200 and 500 micrometers.

7. Light guide according to one of the preceding claims, in which the flexible film (111) comprises microstructures (113) etched by ultraviolet printing so as to return the light injected into the flexible guide sheet (110) according to a given pattern.

8. Light module (100) comprising a light guide (105) according to one of the preceding claims, a first light source (130a) arranged opposite the receiving surface (121) of the first injection assembly (120a) and a second light source (130b) arranged opposite the receiving surface (121) of the second injection assembly (120b).

9. Motor vehicle equipment comprising a light module according to the preceding claim.

10. A method of manufacturing a light guide (105) according to one of claims 1 to 7, comprising the following steps: - positioning (1001) a roll of material (820) on a belt (801) driven by a drive device (802); - translating (1002) said roll so as to process a first portion of the roll of material; - forming (1003; 1004) microstructures in the first portion of the roll of material, the microstructures being formed according to a predetermined light pattern; - cutting (1005) the first portion so as to separate the first portion from the rest of the roll of material; - cutting (1006) the first injection elements of the first injection assembly (120a) and the second elements

11. injection of the second injection assembly (120b). System for manufacturing a light guide (105) according to one of claims 1 to 7, comprising: - a drive device (802) capable of translating a belt capable of supporting a roll of material (820); - at least one device (811; 830) capable of forming microstructures in the first part of the roll of material, the microstructures being formed according to a predetermined light pattern; - a cutting device (840) capable of separating the first part from the rest of the roll of material and of cutting the first injection elements of the first injection assembly (120a) and the second injection elements of the second injection assembly (120b)

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