Light module with electrochromic film

Abstract

The invention relates to a light module (100) comprising a light guide (105) including a light-guiding mat (110) adapted to receive light rays and reflect the light rays in a pattern, and an injection assembly (120) adapted to guide light rays for injection into the light injection channel. The module includes a light source (130) adapted to inject light rays into the injection assembly and an electrochromic film (500) at least partially superimposed on the light-guiding mat. A control element (15) is configured to apply a first electrical voltage to the electrochromic film so as to decrease the transparency of the electrochromic film, following or before activation of the light source, so that the electrochromic film is rendered opaque during a period of activation of the light source. FIG. 6

Description

Title of the invention: Light module with electrochromic film

[0001] The present invention relates to the field of lighting modules, particularly lighting modules for motor vehicles. The invention applies in particular, but not exclusively, to lighting modules comprising a light guide with a guide sheet.

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

[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 unsuitable for many types of equipment whose uses induce variations in environmental conditions, as may be the case for equipment used outdoors.

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

[0006] In addition, the aforementioned solution has the disadvantage of high energy consumption, which is all the more significant as the surface area of ​​the equipment in which the light module is to be integrated is large.

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

[0008] Some light guides use guide sheets whose thickness and material allows a high transparency of the guide sheet, greater than 70%, when no light is injected into the injection edge of the flexible film.

[0009] Such transparency can make visible an object or equipment located behind the light module, or allow light rays emitted by another light module, such as a lighting module (when the light module is not activated), to pass through, making the use of the light module advantageous in many contexts.

[0010] However, when the light module is activated and a pattern is displayed, the contrast associated with the display of the pattern depends on what is located behind the light module. In particular, when the transparency of the light module is used to To make visible an object or equipment located behind, or to allow light rays from another module to pass through the light module, poor contrast is associated with the display of the given pattern.

[0011] There is therefore a need to have a light module with a guide ribbon that is at least partially transparent, capable of displaying at least one light pattern with good contrast.

[0012] The present invention improves the situation.

[0013] A first aspect of the invention relates to a light module, comprising: - at least one light guide comprising a light guide sheet, the guide sheet being capable of receiving light rays through at least one light injection slice, and of reflecting the light rays in a direction substantially normal to the guide sheet according to a pattern, and at least one injection assembly capable of receiving light rays from an inlet surface and of guiding the light rays to inject them into the light injection slice of the guide sheet; - at least one light source capable of injecting light rays into said at least one injection assembly; - an electrochromic film at least partially superimposed on said at least one guide sheet in the light module; - a control element, said control element being configured to apply a first electrical voltage to the electrochromic film so as to decrease the transparency of the electrochromic film from a first level of transparency to a second level of transparency lower than the first level, following an activation of said at least one light source or before said activation of said at least one light source, so that the electrochromic film has the second level of transparency during a period of activation of said at least one light source.

[0014] Each guide rail is preferably at least partially transparent. Thus, the use of an electrochromic film whose opacity can be controlled by applying the first voltage makes it possible to improve the contrast of the displayed pattern, while having a light module that is transparent when the guide rail is transparent, before the first electrical voltage is applied. The drawbacks of existing solutions are thus overcome.

[0015] According to embodiments, the control element can further be configured to apply a second electrical voltage opposite to the first electrical voltage to the electrochromic film before or after the deactivation of said at least one light source, the application of the second electrical voltage increasing the transparency of the electrochromic film from the second level of transparency to the first level of transparency, so that the electrochromic film has the first level of transparency during a period of deactivation of said at least one light source.

[0016] Thus, the increase in the opacity of the electroluminescent film is reversible. It is therefore possible to alternate between periods of activation of the light source, with a pattern displayed with good contrast, and periods of deactivation of the light source, during which the light module is transparent.

[0017] According to embodiments, the electrochromic film is capable of being made totally opaque by application of said first electrical voltage by the control element for a first duration.

[0018] Thus, the contrast of the pattern displayed by the light module is at its maximum.

[0019] According to embodiments, the electrochromic film can have a transparency greater than 75% in the absence of application of the first electrical voltage by the control element.

[0020] Thus, the light module, when the electrochromic film is at rest, is able to let most of the light rays incident on the light module pass through, which makes it possible to obtain a light module with a high level of transparency, especially when the transparency of the guide sheet is high, and thus compatible with many applications.

[0021] According to embodiments, the electrochromic film may comprise a plurality of layers, comprising at least one layer of electrochromic material separated from an ion storage layer by an electrolyte, the ion storage layer being contained between a first layer of conductive substrate and the electrolyte and the layer of electrochromic material being contained between a second layer of conductive substrate and the electrolyte.

[0022] The transparency / opacity of the electrochromic film is thus controlled by controlling the degree of oxidation of the electrochromic material layer, an oxidation which is also reversible. It is therefore possible to increase and then decrease the opacity of the electrochromic film.

[0023] According to embodiments, each guide mat may include a film comprising microstructures arranged to reflect light outwards from said guide mat according to the pattern of the guide mat.

[0024] The use of a film etched with microstructures makes it possible to manufacture light guides by a roll-by-roll process, which facilitates the production of a large number of light guides. Moreover, the use of microstructures makes it possible to obtain a guiding sheet that is at least partially transparent.

[0025] In addition, the film may be made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, polyethylene terephthalate, PET, or silicone, and has a thickness between 50 and 1000 µm. metric meters, for example between 200 and 500 micrometers.

[0026] This makes it possible to obtain a light module with a flexible guide rail and a high degree of transparency, in particular exceeding 90%, or even 97%. Furthermore, this flexibility facilitates the integration of the light module into any type of equipment.

[0027] According to embodiments, the control element may be capable of activating and deactivating said at least one light source as a function of a control signal.

[0028] Thus, the control element controls both the voltage applied to the electrochromic film and the activation of the light source or light sources. Since these elements must be controlled synchronously, this embodiment provides better synchronization than an embodiment in which a separate control unit, distinct from the control element, is responsible for activating the light source.

[0029] According to one embodiment, the light module may include at least a first light guide and a second light guide, the first light guide comprising a first light guide mat, the first guide mat being capable of receiving light rays through at least one light injection slice, and of reflecting the light rays in a direction substantially normal to the first guide mat according to a first pattern, and at least a first injection assembly capable of receiving light rays from an inlet surface and of guiding the light rays to inject them into the light injection slice of the first guide mat.The second light guide comprises a second light guide mat, the second light guide mat being capable of receiving light rays through at least one light injection slice and of reflecting the light rays in a direction substantially normal to the second light guide mat according to a second pattern, and at least one second injection assembly capable of receiving light rays from an inlet surface and of guiding the light rays to inject them into the light injection slice of the second light guide mat. At least one light source is capable of selectively injecting light rays into said at least one first injection assembly and into said at least one second injection assembly.The control element is configured to apply the first electrical voltage to the electrochromic film in such a way as to increase the opacity of the electrochromic film when at least one light source injects light rays into the first injection set or the second injection set. The first light guide and the second light guide are arranged so that the first flexible guide sheet and the second guide sheet overlap at least partially. of guide being able to reflect light rays according to the second pattern at least partially through the first guide layer, the second guide layer being at least partially transparent, the second guide layer being at least partially contained between the first guide layer and the electrochromic film.

[0030] Such a superposition allows the display of several distinct patterns, with high contrast.

[0031] A second aspect of the invention relates to a lighting device for a motor vehicle comprising a light module according to the first aspect of the invention.

[0032] According to a first embodiment, the lighting device comprises a lighting module capable of emitting light rays towards an external lens of the lighting device, and the lighting module can be arranged such that at least one guide rail and the electrochromic film are traversed by the light rays from the lighting module. The control element is configured to apply the first electrical voltage to the electrochromic film upon detection of a deactivation of the lighting module.

[0033] In addition, the light module can be arranged so that the light guide sheet covers at least part of an inner surface of the outer glass, said light module being arranged between the outer glass and the lighting module.

[0034] In addition or alternatively, the control element can further be configured to apply a second electrical voltage opposite to the first electrical voltage to the electrochromic film upon detection of an activation of at least one light function of the lighting module, the application of the second electrical voltage increasing the transparency of the electrochromic film.

[0035] According to a second embodiment, the control element may be capable of controlling said at least one light source so as to selectively inject light beams into said at least a first injection set and into said at least a second injection set, according to a control signal indicating signaling information, so as to display a pattern among the first pattern and the second pattern, the displayed pattern corresponding to the signaling information.

[0036] In addition, in the second embodiment, the signaling information can be a driving mode of motor vehicle.

[0037] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings in which:

[0038] [Fig. 1] illustrates a cross-sectional view of elements of a light guide for a light module according to embodiments of the invention;

[0039] [Fig.2] illustrates a front view of the elements of a light guide for a light module according to embodiments of the invention;

[0040] [Fig.3] illustrates a front view of the elements of a light guide for a light module according to embodiments of the invention;

[0041] [Fig.4] illustrates a three-dimensional view of an injection assembly of a light guide for a light module according to embodiments of the invention;

[0042] [Fig.5] illustrates an electrochromic film comprising a plurality of layers, for a luminous module according to embodiments of the invention;

[0043] [Fig.6] illustrates a front view of a light module according to a first embodiment of the invention;

[0044] [Fig.7] illustrates a cross-sectional side view of a lighting device comprising a light module according to the first embodiment of the invention;

[0045] [Fig.8a] illustrates a front view of a light module according to a second embodiment of the invention, in a first configuration;

[0046] [Fig.8b] illustrates a front view of a light module according to the second embodiment of the invention, in a third configuration;

[0047] [Fig.8c] illustrates a front view of a light module according to the second embodiment of the invention, in a third configuration;

[0048] [Fig.9a] illustrates a front view of a lighting device comprising a light module according to the second embodiment of the invention, in the first configuration;

[0049] [Fig.9b] illustrates a front view of a lighting device comprising a light module according to the second embodiment of the invention, in the second configuration;

[0050] [Fig.9c] illustrates a front view of a lighting device comprising a light module according to the second embodiment of the invention, in the third configuration.

[0051] The description focuses on the characteristics that distinguish the lighting device from those known in the state of the art.

[0052] Fig. 1 presents elements of a light guide 105 of a light module according to embodiments of the invention.

[0053] The light guide 105 comprises a guiding sheet 110, preferably transparent (with a high level of transparency, in particular greater than 70%, or even 90%), and which may be flexible and capable of receiving light rays through at least one light injection channel 114 and of reflecting the light rays in a direction Z substantially normal to a surface of the guiding sheet, which thus extends in an XY plane on the [Fig. 1]. A guiding sheet is understood to be an optical guiding element, one of whose dimensions is much smaller than the other two. dimensions in space, for example smaller by one or more orders of magnitude. As illustrated in [Fig. 1], we consider here a guide sheet 110 whose thickness along the Z axis is smaller by at least two orders of magnitude than its dimensions along the XY plane in which the guide sheet 110 extends.

[0054] The guide sheet 110 may include a film 111 in its core, which may be flexible, including the light injection slice 114, being able to guide light rays in an overall direction X, and including a set of microstructures 113 able to reflect the light rays guided in the film 111 out of the flexible guide sheet 110, in particular in one or more directions substantially along the Z axis.

[0055] The film 111 can be a substrate film made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, polyethylene terephthalate, PET, silicone, or glass. The film 111 can have a thickness, i.e., a dimension along the Z-axis, of between 12 and 1000 micrometers. More precisely, the thickness of the film 111 can be between 25 and 1000 micrometers, in particular between 50 and 1000 micrometers, for example between 200 and 500 micrometers. Alternatively, the guide mat 110 has a thickness of between 200 and 1000 micrometers.

[0056] The aforementioned materials, combined with a low thickness as described above, allow for the production of a flexible and transparent film 111, in particular with a transparency level exceeding 97%. Other materials may be used in the composition of the film 111.

[0057] A thin coating of microstructures 113 can be created on one of the faces of the film 111, or within the film 111. The microstructures are formed on the surface of the film, or within the film, in a distribution that creates a light pattern. The light pattern is obtained from light-extraction zones, which are areas of the film 111 comprising microstructures 113. The light pattern may also include dark areas, which are areas 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 areas together form the light pattern of a guide sheet 110. Alternatively, the light pattern comprises only a light-extraction zone of a given shape.

[0058] Microstructures 113 are understood to be structures, or irregularities, of the flexible film 111, at least one dimension of which is less than a few micrometers. For example, the microstructures 113 may be on the order of 50 micrometers in diameter and 1 or 2 micrometers in height. The microstructures 113 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 around 97% can be obtained in practice by using microstructures 113. Alternatively, the guide sheet can be semi-transparent or partially transparent.

[0059] Such transparency, partial or total, makes it possible to display a light pattern for an observer located in a position in the positive Z half-space, while making visible (when no light ray is injected into the light guide 105) an object or equipment located in the negative Z half-space, or while allowing another light module (or any other light source) located behind the light module 100, to emit light rays through the light module 100.

[0060] The microstructures 113 are capable of redirecting the light injected into the light guide in one or more directions different from the direction of injection 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, notably in a direction directed outwards from the light guide 105. In practice, such microstructures are capable of redirecting the guided light rays in all directions of space, in a Lambertian manner.

[0061] No restrictions are attached to the way in which the microstructures 113 are formed on the face of the film 111. The microstructures 113 can be obtained by adding or subtracting material from the flexible film.

[0062] For example, the microstructures can be obtained by embossing by applying a roller having irregularities to mechanically imprint 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 suitable for forming the microstructures by complementary shape.

[0063] 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 complementaryly, additional surface or volumetric, prismatic, reflective, diffracting, or diffusing elements can be added to the holes or gaps to form the microstructures 113.

[0064] 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 allowing to obtain irregularities in a controlled manner on the face of the film 111.

[0065] Alternatively or in a complementary manner, the microstructures 113 are exogenous elements to the film added to the face of the film 111.

[0066] The microstructure coating 113 may in particular have a thickness along the Z axis of less than 20 micrometers.

[0067] The density of microstructures 113 can vary in the light extraction zones depending on their distance from the light injection slice 114.

[0068] The term “pattern” refers to any predefined spatial distribution or arrangement of the light intensity emitted by the light guide 105. In particular, it refers to a two-dimensional or one-dimensional pattern. A pattern may thus include a homogeneous distribution of light over the entire guide surface, in which case a light extraction zone extends over the entire guide surface. The pattern may also be a two-dimensional shape or symbol obtained by contrasting the light extraction zones with the dark areas of the guide surface 110. The pattern may also include several shapes or symbols. Alternatively, a pattern covers a predefined spatial distribution of light intensity that does not exhibit an overall shape, such as a distribution that induces a cloud of light points.

[0069] As will be better understood from the following, the patterns displayed according to the invention may have an aesthetic function or may be symbols for indicating motor vehicle signaling information.

[0070] The flexible guide sheet 110 may further include one or two optional protective layers 112.1 and 112.2, which provide mechanical protection for the film 111. In addition, at least one of the protective layers 112.1 and 112.2 may include a UV-resistant treatment, preferably the protective layer 112.1, through which the light rays reflected by the microstructures 113 are emitted, thus protecting 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, particularly when exposed to sunlight.

[0071] The film 111 and the protective layers 112.1 and 112.2 are shown spaced apart in [Fig. 1] for illustrative purposes only. It will be understood, however, that the protective layers 112.1 and 112.2 can be bonded to the film 111, in particular by lamination.

[0072] The propagation of light rays in the film 111 is done by total internal reflection thanks to the difference between the refractive index of the film 111 and that of a layer of glue or adhesive applied on at least one face of the flexible film.

[0073] The film 111 can be bonded to the protective layers 112.1 and 112.2 by gluing. Specifically, a layer of glue is located between the film 111 and each protective layers 112.1 and 112.2, and this on both sides of the film to make the protective layers adhere to film 111.

[0074] The chosen adhesive is transparent and has a refractive index different from, and in particular lower than, that of the film, so as to allow total internal reflection within the film 111. For example, the adhesive may be silicone or acrylic. In other words, due to the difference in refractive indices, light rays propagating within the film 111 undergo total internal reflection upon encountering the interface between the film 111 and the adhesive layer at an angle of incidence lower than normal incidence. Thus, the guiding sheet is capable of guiding light by total internal reflection, for example, from an entry zone, here the injection channel 114, to an exit zone.

[0075] The guide sheet 110 being flexible, it is not necessarily contained in a plane but can be curved, depending on the position in which it is placed and the mechanical stresses applied to it.

[0076] The light guide 105 illustrated in [Fig.1] also includes an injection assembly 120 comprising several light injection elements, described with reference to the following figures, the assembly 120 being able to distribute the light in the guide sheet 110 at different positions along the Y axis, along the light injection slice 114. The light is injected, at each position along the Y axis, in a direction substantially parallel to the X axis.

[0077] The injection assembly 120 includes an inlet surface 121 with a rectangular or square cross-section in [Fig. 1]. However, the assembly 120 may have an inlet surface 121 with a cross-section of a different shape.

[0078] In [Fig.1], the injection assembly 120 is shown with an exit surface 122 extending along the Y direction and positioned opposite the light injection slice 114. It will be understood from the description of the following figures that the exit surface 122 and the light injection slice 114 are one and the same, the flexible film 111 and the injection assembly 120 forming a single piece.

[0079] The injection assembly 120 further includes the inlet surface 121, at one end of the injection assembly 120, adapted to receive light rays from a light source external to the light guide 105 and not shown in [Fig. 1], and the injection assembly 120 is adapted to guide the light longitudinally along the Y axis by distributing it on the outlet surface 122. The distribution of light by the outlet surface 122 will be better understood in light of the description of the following figures.

[0080] Figure 2 shows elements of a light module 100 comprising a light guide 105 with an assembly 120 of injection elements and a flexible guide sheet 110, and a light source 130. As further indicated by reference In [Fig.6], the light module 100 according to the invention further comprises an electrochromic film and a control element, not shown in [Fig.2].

[0081] Depending on the distribution of the microstructures 113, the guiding sheet 110, or more precisely the film 111, may comprise a mixing zone 111.2 and a light-emitting zone 111.1, the light-emitting zone comprising at least one light extraction zone provided with the microstructures 113, and optionally one or more dark zones, so as to create a light pattern in the light-emitting zone 111.1. The mixing zone 111.2 is arranged upstream of the light-emitting zone 111.1 along the direction of light ray propagation. The light-emitting zone 111.1 is integrated into a region 1110.

[0082] The light injected into the light guide sheet 110 via the injection channel 114 is mixed in the mixing zone 111.2 to obtain better light homogeneity. The light then propagates in the light emission zone 111.1 through which the light exits the light guide sheet 110 in the Z direction, in particular towards positive Z (i.e. towards the observer in the figure).

[0083] More generally, the mixing zone 111.2 is an area of ​​the flexible guide sheet not including the light pattern emitted by the flexible guide sheet 110, the mixing function of the zone 111.2 being optional.

[0084] The assembly 120 of injection elements 120.1 is suitable for injecting light rays from the source 130 into the injection slice 114 towards the mixing zone 111.2. In [Fig.2], a single injection assembly 120 is shown, for illustrative purposes.

[0085] Note that the light guide 105 can include several injection sets 120 per injection slice 114, each injection set 120 being arranged at a given set of Y positions of the injection slice 114. Each injection set 120 is thus configured to illuminate a different region 1110 in the light guide sheet. In what follows, a single injection set 120 per injection slice 114 is considered, for illustrative purposes.

[0086] 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 clarity, only two light injection elements 120.1 have been referenced.

[0087] 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.

[0088] Since the light injection elements 121 are obtained by cutting the same material as the flexible film 111 and since these elements are stacked one on top of the other, the light rays R will propagate in the light injection elements 120.1 so as to bring light to the light guide sheet which is adjacent and attached to the light injection elements 120.1, and the light will thus illuminate the light extraction zone(s) of the light guide sheet 110.

[0089] 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 from the light source 130 and propagate them in the light guidance sheet 110. The assembly 120 can be of square or rectangular cross-section.

[0090] No restrictions are attached to the light source 130, which can be any light source technology. For example, the light source 130 can be an electroluminescent element, such as an LED, mounted on a substrate 131. A heat dissipation element 132 can also be arranged below the substrate 131.

[0091] The light source 130 can be adapted to generate light within a range of wavelengths. Such a range can be centered around a visible color, in order to generate colored light, for example, blue, red, or green. Alternatively, the light source 130 can emit light rays across the entire range of wavelengths visible to the human eye, so as to generate white light. The light source 130 can be controlled by a control element not shown in [Fig. 2], but described later. Alternatively, the light source 130 is not arranged directly opposite an inlet surface 121 of the injection element 120, but the light module 100 further includes an optical fiber placed between the source 130 and the injection assembly 120, which allows the source 130 to be offset from the light guide 105.

[0092] It is thus made possible to inject light at different longitudinal positions along the Y axis of the injection slice 114.

[0093] The guide sheet 110 can have a width La along the Y axis and a length Lg along the X axis. The light guide 105 can be cut from a roll of the same material as the film 111 and the injection elements 120, the roll extending along the X axis and having the same width La as the light guide 105.

[0094] The references (pj) refer to injection positions of index j, each injection position of index j corresponding to an interval of positions along the Y-axis of injection in the injection slice 114, j varying between 1 and N, N being the number of injection elements 120.1 in the injection set 120 (i.e. N=10 in the example considered so far).

[0095] A non-apparent part 13 of the light module 100 may include the light guide assemblies 120, and said at least one light source 130. Such a part can be hidden, whereas the light emission zones 111.1 of the light guides are, on the contrary, visible from outside of equipment including the light module 100.

[0096] Figure 3 illustrates the light guide of Figure 2 with the light injection elements 120.1 of the injection assembly 120 unfolded. In Figure 3, each injection element 120.1 has a respective length Lh and a width W.

[0097] For clarity in [Fig. 3], only the length Lh and 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. Conversely, the widths W of all the injection elements 120.1 can be equal.

[0098] 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.

[0099] A bending position 300 is further indicated on [Fig.3], each injection element 120.1 being able to be bent on the bending position 300 so that the injection elements 120.1 overlap to form the assembly 120. The respective lengths Lh of the injection elements are determined from the bending position and the respective Y positions of the injection elements, so that their ends together form the injection surface 121.

[0100] Fig. 4 illustrates a three-dimensional view of an injection assembly 120 of a light guide 105, and of a light source 130, of a light module 100 according to embodiments of the invention.

[0101] 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 film 111. The light injection element 120.1 comprises two ends 120.10, one of which, illustrated in [Fig.2], is integral with the guide sheet 110 and the other, illustrated in [Fig.4], is adapted 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.

[0102] It should be noted that during the manufacturing process of the light guide 105, the injection elements 120.1 and the light guide sheet 110 can be 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 bending according to the bending position 300.

[0103] Thus, the light injection elements 120.1 remain attached to the guide mat 110 on their second ends 120.10.

[0104] The respective lengths Lh of the injection elements 120.1 are such that the first ends 120.10 opposite the light source 130 coincide to form the injection surface 121 of the assembly.

[0105] The injection surface 121 thus has a thickness E equal to the sum of the thicknesses e of the injection elements 120.1.

[0106] Figure 5 shows the structure of an electrochromic film 500 of a light module, according to embodiments of the invention. As described later with reference to Figure 6, the electrochromic film 500 is opposite the guide sheet of a light guide in the light module according to the invention.

[0107] The electrochromic film comprises at least one layer of electrochromic material 505 and an ion storage layer 503, separated by an electrolyte 504.

[0108] An electrical voltage can be applied between the electrochromic material layer 505 and the ion storage layer 503, so as to allow the migration of ions from the ion storage layer 503 to the electrochromic material layer 505, thereby oxidizing the electrochromic material layer. For this purpose, a first electrode can be formed by a first conductive substrate layer 502 and a second electrode can be formed by a second conductive substrate layer 506.

[0109] No restrictions are attached to the materials of the first and second layers of conductive substrate 502 and 506. For example, the first layers of conductive substrate 502 and 506 may comprise a non-conductive material on which a conductive coating is deposited, such as a transparent conductive oxide coating, also called TCO for “Transparent Conductive Oxides”, in English, for example a thin layer of indium-tin oxide, also called ITO for “Indium-Tin Oxide” in English.

[0110] Electrochromic means a material that changes color when an electrical voltage is applied to it for a short time. The color change is due to the fact that only a specific type of wavelength, for example, wavelengths of a specific value or within a specific visible color spectrum, can be reflected by the electrochromic material layer, depending on the value of the applied electrical quantity.

[0111] According to the invention, the electrochromic material layer 505 is at least partially transparent at rest, that is, when no electrical voltage is applied to the electrochromic film, and the opacity of the electrochromic material layer increases upon application of a first electrical voltage to the electrochromic film. The electrochromic material layer then appears more opaque and of a color determined by the characteristics of the electrochromic material used, by the thickness of the electrochromic layer 505 and by the voltage applied to the electrochromic film 500.

[0112] A control element 15 is suitable for controlling an electrical voltage applied between the electrochromic material layer 505 and the ion storage layer 503. For example, the storage element can apply the electrical voltage to the first and second substrate layers 502 and 506, so as to force a migration of ions towards the electrochromic material layer 505, via the electrolyte 504, which increases the opacity of the electrochromic material layer 505 and therefore of the electrochromic film 500.

[0113] The increase in opacity is due to an oxidation phenomenon of the electrochromic material layer 505, made possible by the migration of ions towards this layer. It should be noted that the level of oxidation, and therefore the opacity level of the electrochromic material layer, can be adjusted progressively according to the voltage applied to the electrochromic film 500. This oxidation is reversible by applying a voltage opposite to that applied by the control element 15. The electrochromic material layer 505 can thus be made more transparent, up to its resting state, by applying an opposing voltage, referred to as the second voltage hereafter, to the electrochromic film 105, in order to reduce the oxidation of the electrochromic material layer. The ions then migrate in the opposite direction towards the ion storage layer 503. Examples are given below by way of illustration.

[0114] In its resting state, the electrochromic material layer can be transparent, and may in particular have a degree of transparency greater than 90%, preferably greater than 95%. A first voltage, for example equal to IV, is applied to the electrochromic film 500 for a given duration, causing partial or total oxidation of the electrochromic material layer 505, thus increasing its opacity and giving it a given color. The opacity can, in particular, be increased, depending on the duration and value of the first voltage, up to total opacity, i.e., no visible light ray can pass through the electrochromic material layer 505.

[0115] Applying a second electrical voltage by the control element 15, opposite to the first electrical voltage, for example equal to -IV, for a second given duration, for example equal to the first duration, makes it possible to increase the transparency of the electrochromic material layer 505.

[0116] Thus, the control element 15 is capable of controlling the state of the electrochromic material layer 505 entering a resting state, in which the electrochromic material layer 505 is at least partially transparent, with in particular a first high level of transparency, and an oxidized state (partially oxidized or totally oxidized), corresponding to a second reduced level of transparency (or an increased level of opacity, which is equivalent), for example up to a second level of zero transparency, i.e., a level of total opacity.

[0117] The first and second durations may be a few seconds, and may be equal. However, no restrictions are attached to the first and second durations according to the invention.

[0118] The electrochromic film 500 may further comprise a first layer of flexible and transparent material 501 and a second layer of flexible and transparent material 507. The first layer of flexible and transparent material 501 is arranged such that the first layer of conductive substrate 502 is located between the first layer of flexible and transparent material 501 and the ion storage layer 503. The second layer of flexible and transparent material 507 is arranged such that the second layer of conductive substrate 506 is located between the electrochromic material layer 505 and the second layer of flexible and transparent material 507.

[0119] The use of layers of flexible and transparent material on either side of the electrochromic film 500 provides mechanical and chemical protection for the electrochromic film 500. Furthermore, they do not reduce the overall transparency of the electrochromic film 100 when the layer of electrochromic material 105 is at rest. The flexible and transparent material can, for example, be a layer of glass or plastic. Indeed, when the thickness of a glass layer is ultra-thin, particularly on the order of a few tens of micrometers, the glass layer is flexible, and the electrochromic film 500 can thus be flexible.

[0120] The use of thin, or even ultra-thin, layers and suitable materials for the electrochromic film 500 makes it possible both to make the electrochromic film 500 flexible, but also to have a first level of high transparency when the layer of electrochromic material 105 is at rest.

[0121] The first level of transparency corresponds to the ratio of light rays 511 exiting the electrochromic film to incident light rays 510, when the electrochromic material layer 505 is at rest. The thickness of the electrochromic film layers 500 and their respective materials may, in particular, be such that the first level of transparency, when the electrochromic material layer 505 is at rest, is greater than 75%, or even greater than 90%, or even greater than 95%.

[0122] When the first electrical voltage is applied during the first given duration, the overall transparency level can drop to a second transparency value which is below 10%, or even below 5%, or can even reach 0% in the case of total opacity, due to the oxidation of the electrochromic material layer 505.

[0123] The term “film” means an object in which one dimension is small compared to the other two dimensions, in particular more than 10 times smaller, or even more than 100 times smaller. The 500 electrochromic film meets this definition in that its thickness, i.e. its dimension along the Z axis in [Fig. 1], is at least 10 times smaller than its dimensions along the X and Y axes. It will thus be understood that the width along the Y axis represented in [Fig. 5] is given for illustrative purposes, but that the width along the Y axis is much greater than the thickness along the Z axis in reality.

[0124] The electrochromic material of layer 505 can for example be a tungsten oxide, such as tungsten trioxide WO3 for example, the properties of which are described in the publication “Review of the versatility of Tungsten Oxide Coatings”, Cezarina C. Mardare and Achim W. Hassel, Phys. Status Solidi A, 2019, published by Wiley-VCH Verlag GmbH&Co KHaA, Weinheim.

[0125] Alternatively, the electrochromic material of layer 505 may be a polymer, such as a PEDOT-type polymer, or poly(3,4-ethylenedioxythiophene), or PEDOT:Tosylate.

[0126] Of course, other materials can be used as long as they have properties suitable for automotive applications, such as high ionic conductivity and a transparent appearance in a resting state (i.e., with a high initial level of transparency), and flexibility. Furthermore, the material can be packaged as a solid cell. The electrochromic material can, in particular, be an organic or an inorganic material.

[0127] The electrochromic material may be a transparent conductive oxide, or TCO for "Transparent Conductive Oxide". In particular, among organic electrochromic materials, the electrochromic material may be a transparent conductive polymer of the type PEDOT:PSS, PEDOTdos, PMMA, T34bT or polycarbonate.

[0128] PEDOT:PSS denotes poly(3,4 ethylenedioxythiophene): sodium poly(styrene-sulfonate);

[0129] PEDOT:Tos designates poly(3,4 ethylenedioxythiophene):Tosylate;

[0130] PMMA stands for Polymethyl MethAcrylate;

[0131] T34bT denotes 2-alkylthieno[3,4-b]thiophene.

[0132] Figure 6 presents a light module 100 according to a first embodiment of the invention.

[0133] The light module 100 according to the invention comprises: • at least one light guide 105, as described above with reference to Figures 1 to 4, comprising a light guide mat 110, the guide mat being capable of receiving light rays through the light injection edge 114, and of reflecting the light rays in the Z direction substantially normal to the guide mat 110 in a pattern, and at least one injection assembly 120 capable of receiving light rays from an inlet surface and of guiding the light rays for injection in the light injection slice of the guide sheet 110; • at least one light source 130, as described previously with reference to Figures 1 to 4, capable of injecting light rays into each injection set; • an electrochromic film 500, as described previously with reference to [Fig.5], at least partially superimposed, in the XY plane, on said at least one guide sheet 110 in the light module 100; • a control element 15, as described previously with reference to [Fig.5].

[0134] According to the invention, the control element 15 is configured to apply a first electrical voltage to the electrochromic film so as to decrease the transparency of the electrochromic film from the first transparency level to the second transparency level, which is lower than the first level, following activation of the light source 130, or before activation of the light source 130, so that the electrochromic film has the second transparency level for a period of activation of said at least one light source. Advantageously, the control element 15 may further be capable of controlling the activation and deactivation of at least one light source 130.Alternatively, the control element 15 is connected to a control unit of at least one light source, and is capable of receiving information relating to the activation and deactivation of at least one light source 130, from the control unit, not shown in the figures.

[0135] Thus, the electrochromic film is rendered opaque while at least one of the light guides transmits light rays according to a given pattern. Consequently, the given pattern is displayed against an opaque background, formed by the electrochromic film having the second, lower level of transparency, which improves the contrast associated with the display of the given pattern, compared to a light module 100 that does not include the electrochromic film 500.

[0136] The electrochromic film 500 can be made opaque (second level of transparency) just before the activation of the light source 130 (for example, less than one second before the activation of the light source 130), just after the activation of the light source 130 (for example, less than one second after the activation of the light source), or at the same time as the activation of the light source 130. Thus, the electrochromic film 500 is made opaque only when a pattern is displayed by one of the light guides 105, and is transparent (first level of transparency) if no pattern is displayed by a light guide 105.

[0137] Furthermore, as mentioned previously, the transition from the first transparency level to the second transparency level is reversible. Thus, the control element 15 can also be configured to apply a second voltage electric opposite to the first electric voltage to the electrochromic film 500 before a deactivation of the light source 130 or following the deactivation of the light source, the application of the second electric voltage increasing a transparency of the electrochromic film from the second level of transparency to the first level of transparency, so that the electrochromic film has the first level of transparency during a period of deactivation of the light source.

[0138] Thus, the electrochromic film 500 becomes transparent again (first level of transparency) when at least one light source 130 is switched off. The light module 100 is therefore transparent when it displays no pattern, which makes any equipment or object located behind the light module 100 visible to an outside observer, or allows light rays emitted by another light source to pass through.

[0139] The light module 100 according to the invention can advantageously be integrated into a motor vehicle, either inside the vehicle, to perform aesthetic or information display functions, or outside the vehicle, particularly in a lighting system. The light module 100 can also be integrated into the vehicle's windows or glass.

[0140] In the first embodiment illustrated in [Fig.6], the light module 100 comprises a single light source 130 and a single light guide 105, with a single injection assembly 120. In addition, as mentioned previously, the light module 100 comprises an electrochromic film 500 and a control unit 15.

[0141] The control unit 15 can also control the activation and deactivation of the light source 130.

[0142] In the example shown in [Fig.6], the guide sheet 110 is capable of displaying a luminous pattern in the form of a star, such an example being given for illustrative purposes only.

[0143] Figure 7 presents a cross-sectional view of a 700 motor vehicle lighting device comprising a light module according to the first embodiment of the invention.

[0144] The lighting device 700 includes at least one lighting module 710 capable of performing at least one lighting function, such as a lighting and / or signaling function.

[0145] For example, the lighting module 710 can perform: a dipped beam function, also called LB for “Low Beam” in English; a main beam function, also called HB for 'High Beam' in English; and / or a position light function, also called PL for “Position Lighting” in English.

[0146] The lighting module 710 may in particular be capable of performing the three LB functions, HB and PL mentioned above, according to certain embodiments of the invention.

[0147] In order to perform one or more of these functions, the lighting module 710 includes at least one light source not shown in [Fig. 7]. Such a source may be a pixelated source comprising a plurality of individually controllable light elements. The light elements may, for example, be electroluminescent light elements, controllable by the electric current supplied to each of them. However, there are no restrictions on the technology associated with the light source, or light sources, of the lighting module 710.

[0148] The lighting module 710 is thus able to project light beams 711 outside the lighting module 710, towards an external glass 702 of the lighting device 700, the external glass 702 being at least partially transparent, preferably with a high level of transparency, greater than 75%, in particular greater than 90%, or even greater than 99%.

[0149] The lighting module 710 can be arranged in a housing 701 of the lighting device 700, the housing 701 being shaped to receive the lighting module 710, and to fix and adjust the orientation of the lighting module 710 inside the lighting device 700.

[0150] The light module 100 according to the invention can then be placed in the path of the light rays 711 emitted by the lighting module. For example, the light module can be arranged, as shown in [Fig. 7], between the lighting module 710 and the outer glass 702, so that the light rays 711 pass through the electrochromic film 500 in its thickness and the guide sheet 110 also in its thickness.

[0151] When the lighting module 710 is not activated, i.e., when no light beam 711 is projected, which most often occurs during daytime driving, the control element 15 is capable of activate the light source 130 of the light module 100; and apply the first voltage to the electrochromic film 500 of the light module 100 so as to increase its opacity compared to its resting state, by partial or total oxidation of the electrochromic layer 105. Preferably, the control element 15 applies the first voltage for a first duration, so that the transparency of the electrochromic film 500 is equal to the second level of transparency, less than 10%, for example less than 5%.

[0152] When the lighting module 710 is activated, i.e. when light beams 711 are projected to perform at least one lighting function, the control element 15 is able to increase the transparency of the electrochromic film 100 to the first level of transparency and to deactivate the light source 130. Thus, the light module 130 is deactivated and made transparent, which allows the lighting function of the lighting module 710 to be performed.

[0153] For this purpose, the second voltage is applied for a second duration so that the layer of electrochromic material 105 returns to its rest state, that is to say its minimum oxidation state, in which the transparency of the electrochromic film 500 is equal to the first level of transparency, that is to say greater than 90%, in particular greater than 95%, or even greater than 99%.

[0154] The application of the first voltage during the first duration to the electrochromic layer 500 and the activation of the light source 130 can be implemented by the control element 15 upon detection of the deactivation of the lighting module 710. For this purpose, the control element 15 can also be capable of controlling the activation and deactivation of the lighting module 710.

[0155] In addition, the application of the second voltage during the second duration and the deactivation of the light source 130 can be implemented by the control element 15 upon detection of the deactivation of the lighting module 210.

[0156] In order to detect the activation state of the lighting module 710, the control element 15 is capable of communicating with a control module of the lighting module 710, which can be a control module dedicated to the lighting module 710, a control module dedicated to the lighting device 700 or a centralized vehicle control module, of the ECU type for example, for “Electronic Control Unit”.

[0157] Alternatively, the control element 15 is capable of activating / deactivating the lighting module 710, or even of controlling all the light modules of the lighting device 700. In this variant, the control element 15 is capable of determining the activation state of the lighting module 710 itself, and of controlling the voltage applied to the electrochromic film 500 as well as the activation / deactivation of the light source 130.

[0158] Furthermore, the light module 100 can advantageously be flexible, the electrochromic film 500 and the guide sheet 110 being themselves flexible, which makes it easier to arrange it in the lighting device 700. In particular, it can be arranged against the outer glass 702 to adopt the same curvature as an inner surface of the outer glass 702. Alternatively, the overlap of the guide sheet 110 and the electrochromic film 500 is flat, without curvature, and extends in a plane substantially parallel to the XY plane.

[0159] The light module 100 is thus arranged so as to be traversed by light rays 711 projected by the lighting module 710 in a direction substantially along the X-axis, that is to say, light rays forming angles of less than 20° with the X-axis. When the light module 100 is made transparent by the element of control 15, the light rays 711 (or a large part of the light rays 711) pass through the light module (therefore successively the electrochromic film 500 then the guide sheet 110) and then pass through the external glass 702 to form the light rays 712 performing the lighting function.

[0160] The lighting device 700 for motor vehicle is preferably a motor vehicle headlight, for example a motor vehicle headlight.

[0161] No restrictions are attached to the number of lighting modules and signaling modules included in the lighting device 200, nor to their respective shapes and arrangements.

[0162] When the lighting device 700 comprises several lighting modules, light modules 100 according to the invention can be arranged respectively on the path of the light rays of the lighting modules.

[0163] Thus, each light module 100 can be activated by making the electroluminescent film 500 opaque and activating the light source 130, when the lighting modules are deactivated, which prevents an observer from seeing the lighting modules inside the housing 701 of the lighting device 700 and makes it possible to improve the contrast of the displayed light pattern.

[0164] The activation / deactivation detection of the lighting module 710 can be based on the activation / deactivation state of a signaling module of the lighting device 700, which performs a daytime running light (DRL) signaling function. When the DRL signaling module is activated, the lighting module 710 is deactivated, and consequently, the first voltage can be applied by the control element 15 to increase the opacity of the electrochromic film 500, and the light source 130 can be activated. Conversely, when the DRL signaling module is deactivated, the lighting module 700 is activated, and consequently, the second voltage can be applied by the control element 15 to decrease the opacity, or increase the transparency, of the electrochromic film 500, and the light source 130 is deactivated.

[0165] The lighting device 700 may include a single outer glass 702 comprising several parts, each part being opposite a lighting module or a signaling module.

[0166] Figures 8a to 8c illustrate a front view of a luminous module 100 according to a second embodiment, in three different configurations.

[0167] As in the first embodiment, the light module 100 according to the second embodiment comprises an electrochromic film 500, controlled by a control element 15. However, unlike the first embodiment, the light module 100 according to the second embodiment comprises several light guides, the guide sheets of which are at least partially covered perposed, such a superposition being opposite the electrochromic film 500. Each guide sheet is capable of displaying a light pattern different from that of the other guide sheets.

[0168] In particular, according to the example in Figures 8a to 8c, the light module 100 comprises: - a first light guide 105.1, comprising a first guide mat 110.1 and a first injection assembly 120.1, conforming to the description in figures 1 to 4; - a second light guide 105.2, comprising a second guide mat 110.2 and a second injection assembly 120.2, conforming to the description in figures 1 to 4; - a third light guide 105.3, comprising a third guide mat 110.3 and a third injection assembly 120.3, in accordance with the description in figures 1 to 4.

[0169] The light guides 105.1 to 105.3 are arranged so that the guiding sheets 110.1 to 110.3 are at least partially superimposed, that is to say, they occupy a set of common positions in XY. In other words, a light ray directed substantially along the Z axis can successively pass through the three guiding sheets 110.1 to 110.3.

[0170] The first guide sheet 110.1 is located above the second guide sheet 110.2, i.e. the Z position of the first guide sheet 110.1 is greater than the Z position of the second guide sheet 110.2, when the guide sheets are arranged so as to emit light rays in the direction of the positive Zs, the observer in Figures 8a to 8c being in the half-space of the positive Zs.

[0171] Similarly, the second guide plate 110.2 is located above the third guide plate 110.3, that is to say that the Z position of the second guide plate 110.2 is greater than the Z position of the third guide plate 110.3.

[0172] Each of the guide rails is capable of displaying a different light pattern. The first guide rail 110.1 is capable of emitting light rays according to a first pattern 150.1 illustrated in [Fig. 8a], when light rays are injected into the first injection assembly 120.1. The second guide rail 110.2 is capable of emitting light rays according to a second pattern 150.2 illustrated in [Fig. 8b], when light rays are injected into the second injection assembly 120.2. The third guide rail 110.3 is capable of emitting light rays according to a third pattern 150.3 illustrated in [Fig. 8c], when light rays are injected into the third injection assembly 120.3.

[0173] The first guide mat 110.1 being transparent, the emitted light rays according to the second pattern 150.2 by the second guide sheet 120.2 towards the positive Z can cross the first guide sheet 110.1.

[0174] Similarly, the second guide sheet 110.2 being transparent, the light rays emitted according to the third pattern 150.3 by the third guide sheet 120.3 towards the positive Z can pass through the second guide sheet 110.1 and then the first guide sheet 110.1.

[0175] According to the second embodiment, the electrochromic film 500 is arranged below the superposition of guide sheets 110.1 to 110.3, that is to say at a Z position lower than the Z position of the third guide sheet 110.3 located below the other two guide sheets 110.2 and 110.1.

[0176] Thus, the contrast is improved regardless of which pattern is projected among the first pattern 150.1, the second pattern 150.2 and the third pattern 150.3.

[0177] In the example of figures 8a to 8c: - a first light source 130.1 is capable of injecting light rays into the first injection set 120.1, when activated, so as to display the first pattern 150.1; - a second light source 130.2 is capable of injecting light rays into the second injection set 120.2, when activated, so as to display the second pattern 150.2; and - a third light source 130.3 is capable of injecting light rays into the third injection set 120.3, when activated, so as to display the third pattern 150.3.

[0178] Alternatively, the light module 100 according to the second embodiment comprises a single light source, capable of selectively injecting light rays either into the first injection set 120.1, or into the second injection set 120.2, or into the third injection set 120.3.

[0179] In the example shown in Figures 8a to 8c, the control element 15, in addition to being able to control the voltage applied to the electrochromic film 500, is able to selectively control, i.e. to activate and deactivate, each of the three light sources 130.1 to 130.3.

[0180] Alternatively, control units other than the control element 15 may be dedicated to the activation and deactivation of the light sources 130.1 to 130.3.

[0181] Preferably, the control element 15 is capable of activating one of the light sources 130.1 to 130.3, and deactivating the other light sources, so as to display only one pattern. Alternatively, activating two light sources can allow the display of two complementary patterns.

[0182] According to the invention, before at least one of the light sources 130.1 to 130.3 is activated, or following the activation of at least one of the light sources 130.1 to 130.3, the control element 15 is capable of applying the first electrical voltage to the electrochromic film 500 so as to make it opaque (second level of transparency), thus improving the contrast of the displayed pattern, for an outside observer.

[0183] Figures 9a to 9c illustrate a front view of a lighting device 900 comprising a light module 100 according to the second embodiment, in three different configurations.

[0184] The lighting device 900 thus includes a light module 100 capable of displaying several distinct patterns, the light module 100 comprising a superposition of several guide sheets 110 as previously described.

[0185] The light module 100 can thus be capable of displaying signaling information for observers outside the lighting device 900, in particular for road users when the lighting device 900 is integrated into a motor vehicle.

[0186] To this end, the control element 15 can be adapted to receive a control signal indicating signaling information corresponding to one of the patterns 150.1 to 150.3. Upon receiving the control signal, the control element 15 is adapted to activate the light source 130.1, which is capable of displaying the signaling information indicated in the control signal. In addition, the control element applies the first electrical voltage to the electrochromic film 500 so as to make it opaque and improve the contrast of the signaling information.

[0187] For example, signal information can be a mode of driving the motor vehicle.

[0188] An end signal can also be received by the control element 15, indicating to deactivate all the light sources 130.1 to 130.3 of the light module 100. Upon receipt of the end signal, the control element 15 is able to deactivate all the light sources 130.1 to 130.3, and furthermore to apply the second electrical voltage to the electrochromic film 500 in order to make it transparent (first level of transparency corresponding to the rest state), which makes the light module 100 transparent.

[0189] The lighting device 900 may further include one or more lighting modules and / or a signaling module. In the example of Figures 9a to 9c, the lighting device 900 further includes two lighting and / or signaling modules 901.1 and 901.2.

[0190] Regardless of the embodiment considered, the control element 15 may include a processor configured to communicate unidirectionally or bidirectionally, via one or more buses or via a wired connection, with a memory such as a Random Access Memory (RAM) or a memory of The memory can be of the "Read Only Memory" type, ROM, or any other type of memory (Flash, EEPROM, etc.). Alternatively, the memory can include several of the aforementioned types. Preferably, the memory is non-volatile. The processor is capable of executing instructions, stored in the memory, to control the voltage applied to the electrochromic film 500, and optionally to at least one light source 130. Alternatively, the processor can be replaced by a microcontroller designed and configured to control the electrochromic film 500, and optionally at least one light source 130.

[0191] The present invention is not limited to the embodiments described above by way of example; it extends to other variants.

Claims

Claims

1. Light module (100), comprising: - at least one light guide (105; 105.1; 105.2; 105.3) comprising a light guide sheet (110; 110.1; 110.2; 110.3), the guide sheet being capable of receiving light rays by at least one light injection edge (114), and of returning the light rays in a direction substantially normal to the guide sheet according to a pattern (150.1; 150.2; 150.3), and at least one injection assembly (120; 120.1; 120.2; 120.3) capable of receiving light rays from an entry surface (121) and of guiding the light rays to inject them into the light injection edge of the guide sheet; - at least one light source (130; 130.1; 130.2; 130.3) capable of injecting light rays into said at least one injection assembly; - an electrochromic film (500) at least partially superimposed on said at least one guide sheet in the light module; - a control element (15), said control element being configured to apply a first electrical voltage to the electrochromic film so as to decrease a transparency of the electrochromic film from a first transparency level to a second transparency level lower than the first level, following an activation of said at least one light source or before said activation of said at least one light source, so that the electrochromic film has the second transparency level during a period of activation of said at least one light source.

2. The light module of claim 1, wherein the control element (15) is further configured to apply a second electrical voltage opposite to the first electrical voltage to the electrochromic film (500) before a deactivation of said at least one light source (130; 130.1; 130.2; 130.3) or following the deactivation of said at least one light source, the application of the second electrical voltage increasing a transparency of the electrochromic film from the second transparency level to the first transparency level, such that the electrochromic film has the first transparency level during a period of deactivation of said at least one light source.

3. Light module according to claim 1 or 2, in which the electrochromic film (500) is capable of being totally opaque by application of said first electrical voltage by the control element (15) for a first duration.

4. Light module according to one of claims 1 to 3, in which the electrochromic film (500) has a transparency greater than 75% in the absence of application of the first electrical voltage by the control element (15).

5. A light module according to one of the preceding claims, wherein the electrochromic film (500) comprises a plurality of layers (501-507), comprising at least one layer of electrochromic material (505) separated from an ion storage layer (503) by an electrolyte (504), the ion storage layer being comprised between a first layer of conductive substrate (502) and the electrolyte and the layer of electrochromic material being comprised between a second layer of conductive substrate (503) and the electrolyte.

6. Light module according to one of the preceding claims, in which each guide sheet comprises a film (111) comprising microstructures (113) arranged so as to reflect the light towards the outside of said guide sheet according to the pattern (150.1-150.3) of the guide sheet (110; 110.1; 110.2; 110.3).

7. A light module according to claim 6, wherein the film (111) is made of polycarbonate, PC, polymethyl methacrylate, PMMA, thermoplastic polyurethane, TUP, polyethylene terephthalate, PET, or silicone, and has a thickness of between 50 and 1000 micrometers, for example between 200 and 500 micrometers.

8. Light module according to one of the preceding claims, wherein the control element (15) is capable of activating and deactivating said at least one light source (130; 130.1; 130.2; 130.3) as a function of a control signal.

9. Light module according to one of the preceding claims, comprising at least a first light guide (105.1) and a second light guide (105.2), the first light guide comprising a first light guide sheet (110.1), the first guide sheet being capable of receiving light rays by at least one light injection edge (114), and of returning the light rays in a direction substantially normal to the first guide sheet according to a first pattern (150.1), and at least one first injection assembly adapted to receive light rays from an input surface (121) and to guide the light rays to inject them into the light injection edge of the first guide sheet; the second light guide comprising a second light guide sheet (110.2), the second guide sheet being adapted to receive light rays by at least one light injection edge, and to return the light rays in a direction substantially normal to the second guide sheet according to a second pattern (150.2), and at least one second injection assembly (120.2) adapted to receive light rays from an input surface and to guide the light rays to inject them into the light injection edge of the second guide sheet; wherein said at least one light source (130; 130.1; 130.2;130.3) is capable of selectively injecting light rays into said at least one first injection assembly and into said at least one second injection assembly; and wherein the control element (15) is configured to apply the first electrical voltage to the electrochromic film (500) so as to increase an opacity of the electrochromic film, when said at least one light source injects light rays into said first injection assembly or into said second injection assembly;wherein the first light guide and the second light guide are arranged such that the first flexible guide sheet and the second guide sheet overlap at least partially, the second guide sheet being capable of returning the light rays according to the second pattern at least partially through the first guide sheet, the second guide sheet being at least partially transparent, the second guide sheet being at least partially comprised between the first guide sheet and the electrochromic film.;

10. Lighting device (700; 900) for a motor vehicle comprising a light module (100) according to one of the preceding claims.

11. Lighting device (700) according to claim 10, comprising a lighting module (710) capable of emitting light rays towards an outer glass (702) of the lighting device, and in which the light module is arranged so that said at least one guide sheet (110) and the electrochromic film (500) are crossed by the light rays from the lighting module; and wherein the control element (15) is configured to apply the first electrical voltage to the electrochromic film upon detection of deactivation of the lighting module.

12. Lighting device according to claim 11, wherein the light module (100) is arranged such that the guide sheet (110) of the light guide (105) covers at least a portion of an inner surface of the outer glass (702), said light module being arranged between the outer glass and the lighting module.

13. Lighting device according to claim 11 or 12, wherein the control element (15) is further configured to apply a second electrical voltage opposite to the first electrical voltage to the electrochromic film (500) upon detection of an activation of at least one light function of the lighting module (710), the application of the second electrical voltage increasing a transparency of the electrochromic film.

14. Lighting device (900) according to claim 10, comprising a light module (100) according to claim 8, wherein the control element (15) is adapted to control said at least one light source (130; 130.1; 130.2; 130.3) so as to selectively inject light rays into said at least one first injection assembly (120.1) and into said at least one second injection assembly (120.2), as a function of a control signal indicating signaling information, so as to display a pattern among the first pattern (150.1) and the second pattern (150.2), the displayed pattern corresponding to the signaling information.

15. Lighting device (900) according to claim 14, wherein the signaling information is a motor vehicle driving mode.

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