Optical device for a motor vehicle and motor vehicle comprising such an optical device

Abstract

The invention relates to an optical device (1, 2) for a motor vehicle, comprising: − a transparent protective element (10) comprising an outer face (10.1) and an inner face (10.2); − a luminous device, said first luminous device comprising: • a light guide comprising a transparent and flexible light guide layer (12), said light guide layer (12) comprising an outer surface (12.1) and an inner surface (12.2) on the opposite side from the outer surface, said outer surface (12.1) being fastened to the inner face (10.2) of the transparent protective element (10), • a light source (13) suitable for injecting light emitted by the first light source (13) into a region of the light guide layer; and − an optical unit (14) or a sensor (15) positioned facing the inner surface (12.2) of the light guide layer (12).

Description

Description Title of the invention: Optical device for motor vehicle and motor vehicle comprising the optical device TECHNICAL FIELD OF THE INVENTION [1] One aspect of the present invention relates to a lighting assembly for a motor vehicle comprising a signaling or display lighting device. The lighting device is associated with a light source having a signaling or lighting function, or with an optical sensor. [2] The invention further relates to a motor vehicle comprising the optical device according to the first aspect of the invention. TECHNOLOGICAL BACKGROUND OF THE INVENTION [3] Motor vehicles are generally equipped with lighting devices, intended to illuminate the road, and signaling devices, intended to inform other drivers or pedestrians of the vehicle's presence. Motor vehicles are also equipped with sensors, used, for example, to detect obstacles or the presence of other vehicles on the road. Lighting devices with signaling and / or illumination functions and sensors are part of the optical devices of a motor vehicle. [4] In a vehicle, according to the state of the art, lighting devices must perform several functions to allow the driver to steer safely without endangering other road users. Examples of lighting functions include: low beam headlights, high beam headlights, and fog lights. Similarly, signaling devices must perform several functions, allowing other drivers to identify the vehicle's position and any changes in direction or speed. Examples of signaling functions include: daytime running lights, position lights, reversing lights, brake lights, and position indicators. More recently, a driving mode indicator has been introduced to signal to other drivers that the vehicle is in autonomous driving mode. [5] Each of these functions, also called photometric functions, must comply with the regulations in force in the countries in which the vehicle will be used. These regulations may include requirements for colorimetry, intensity, spatial distribution according to a photometric grid, or visibility ranges of the emitted light. [6] Given the very limited space available inside a motor vehicle, car manufacturers today must design lighting systems capable of combining several regulated photometric, lighting, or signaling functions, which can make these systems very complex and expensive. These constraints can also affect the external appearance of signaling and / or lighting devices such as headlights or taillights. [7] For example, in the state-of-the-art headlights of motor vehicles, the implementation of a signaling function such as a daytime running light with a specific shape desired by the manufacturer inevitably imposes constraints on the implementation of the lighting functions. In other words, it is currently difficult to freely choose the appearance of the signaling functions without altering the appearance of the lighting functions, and vice versa. [8] Car manufacturers encounter similar difficulties when they wish to add display functions, for example for decorative purposes, in addition to signaling and lighting functions. Display functions here refer to functions that are not regulated photometric functions. Such display functions may include, for example, the display of a manufacturer's logo or certain animations. It is currently very complicated to add display functions to lighting and / or signaling devices while complying with existing regulations and without imposing additional constraints on the appearance of the devices themselves. [9] A similar problem exists for other optical devices in motor vehicles, such as sensors. Indeed, it is not currently known how to combine automotive sensors and lighting devices with a signaling or display function without interfering with the sensors. SUMMARY OF THE INVENTION

[0010] To address the problems mentioned above, the invention relates to a lighting system for motor vehicles combining an optical unit performing a function of signaling and / or lighting, and / or a sensor, with a flexible and transparent lighting device. Thanks to its characteristics, the lighting device does not impose constraints on the appearance of the optical unit or the sensor included in the lighting assembly according to one aspect of the invention.

[0011] According to a first aspect, the invention relates to a motor vehicle lighting system comprising: - A protective element comprising an outer face and an inner face opposite to the outer face; - A lighting device, also called the primary lighting device, comprising: • a light guide comprising a light guide sheet, said light guide sheet comprising an external surface and an internal surface opposite the external surface, said external surface being fixed to the internal face of the transparent protective element; - at least one suitable light source to inject light into a region of the light-guiding sheet; and - an optical unit configured to perform at least one photometric function of a motor vehicle and / or a sensor positioned opposite the internal surface of the light guide mat.

[0012] In the proposed lighting assembly, the protective element is transparent, allowing light rays emitted by the optical unit to pass through when it is operating to perform one or more photometric functions of the motor vehicle. Naturally, the protective element, being transparent, does not prevent external light from passing through.

[0013] Furthermore, the light guide mat is flexible so that it can be deformed during the mounting of the lighting device within the lighting assembly. For example, the light guide mat can be made of a material with a high modulus of elasticity, giving it the flexibility to deform during the mounting of the lighting device.

[0014] The light-guiding mat also has a similar degree of transparency to the protective element. Here, "degree of transparency" refers to... similar a same value of light transmission rate between the protective element and the light guiding sheet with a margin of + / -10%.

[0015] Thus, when the light guide mat is attached to the protective element, the combined effect of these two elements does not impede the propagation of light from the optical unit, ensuring its proper operation. Furthermore, the light guide mat and the protective element do not block external light rays from illuminating the optical unit and / or the sensor. Consequently, the optical unit and / or the sensor are visible from the outside through the entire light guide mat and the protective element.

[0016] Finally, the light-guiding mat is configured to guide light by total internal reflection and to emit light towards the transparent protective element. Thus, the light guide incorporating such a light-guiding mat is self-sufficient in propagating light from an input zone to an output zone, in this case towards the protective element. Therefore, no additional elements, such as an extra reflective layer, are needed to guide the light rays. The proposed lighting device is a simple and easy-to-handle structure.

[0017] The lighting assembly of a motor vehicle is defined as a device comprising at least one element configured to emit light. A lighting assembly may also include a sensor.

[0018] An optical unit is defined as a device comprising at least one light source and configured to perform a photometric function in a motor vehicle. A photometric function might be, for example, a lighting and / or signaling function visible to the human eye. In the automotive sector, this photometric function may comply with the regulations in force in the country where it will be used; it is then referred to as regulatory. Examples of regulatory photometric functions include: - Daytime running lights (DRL), UNECE regulation 087, - the position light, UNECE regulation 007, - the coded light, UNECE regulations 112 and 98, - the high beam, UNECE regulations 98 and 112, - the reversing light, UNECE regulation O23, - the brake light, UNECE regulation 007, - the direction indicator, UNECE regulation 006, - fog lights, UNECE regulations 019 and 038, - the regulations may contain requirements for colorimetry, intensity, spatial distribution according to a so-called photometric grid or even visibility ranges of the emitted light.

[0019] An optical unit may also include optical elements such as a lens, objective lens, or polarizer.

[0020] For example, the sensor could be a lidar (Light Detection and Ranging), a device for measuring distance based on analyzing the properties of a light beam reflected back to its source. Alternatively, the sensor could be a radar, particularly one operating at a frequency between 76 and 81 gigahertz. The sensor could also be an infrared camera or a camera operating in the visible spectrum. Alternatively, the sensor could be a combination of at least two of the elements mentioned above.

[0021] The light assembly according to the first aspect of the invention can therefore be used as a front or rear light for a vehicle.

[0022] A transparent protective element, also known as a coverlens or outer glass (in English terminology), is a component that is transparent to the light emitted or captured by the light fixture. This transparent protective element isolates the light fixture from the external environment, thus protecting its components.

[0023] The transparent protective element is therefore delimited by an inner face and an outer face, the outer face being the face closest to the outside of the vehicle.

[0024] Similarly, the light guide sheet is delimited by an internal surface and an external surface, the external surface being the face closest to the outside of the vehicle and therefore opposite the internal face of the transparent protective element.

[0025] A light-guiding sheet is defined as a flexible and transparent optical guiding element where one dimension is significantly smaller than the other two dimensions in space. Here, we consider a flexible guiding sheet whose thickness—that is, the distance between the outer and inner surfaces of the guiding sheet—is at least two orders of magnitude smaller than its dimensions in the plane of the sheet. For example, the guiding sheet has a thickness between 200 and 1000 micrometers and extends over several centimeters in the plane of the sheet.

[0026] The light guide mat is designed to receive light rays emitted by the first light source and to reflect said light rays back towards the transparent protective element in a direction substantially perpendicular to the plane of the mat. In other words, the light guide mat is adapted to emit light rays outwards from the vehicle.

[0027] As is known, the guidance system incorporates optical decoupling elements that extract light propagating within the system. For example, these decoupling elements are micro-etchings present in the guidance system. In the device according to the first aspect of the invention, the rays are therefore emitted towards the transparent protective element and thus outwards from the vehicle.

[0028] According to one aspect of the invention, the optical decoupling elements can be arranged uniformly within the light-guiding sheet, giving an illuminated appearance to the entire sheet, or they can be grouped together according to a predefined spatial distribution to form a luminous pattern. The pattern can be a shape, a symbol, or a combination of both.

[0029] The lighting assembly according to the invention allows for the combination of a lighting device, an optical unit, and / or a sensor. The lighting device is fixed to the inner face of the transparent protective element, which thus serves as a support element for the flexible and transparent guide rail.

[0030] The light source is spatially separated from the optical unit and / or sensor, which are positioned opposite the inner surface of the light guide mat. The presence of the light source, which has a flexible and transparent emissive surface, does not impose any constraints on the shape or operation of the optical unit or sensor positioned within the light assembly.

[0031] For example, the lighting device can perform a primary signaling function, while the optical unit can perform a secondary signaling function and / or a lighting function. Since the lighting device does not alter the structure or function of the optical unit, the lighting assembly according to the invention allows for considerable flexibility in the design of lighting assemblies for motor vehicles.

[0032] Furthermore, since the lighting system is completely independent of the optical unit, it can perform display functions. In addition, the guide ribbon presenting a surface area of ​​up to several tens of square centimeters, it can be used as a screen to display animations.

[0033] Thanks to the flexibility of the light guide mat, the lighting fixture can conform to the shape of the inner face of the transparent protective element, thus reducing its overall size. The transparent protective element also acts as a support for the light guide mat.

[0034] Similarly, the lighting assembly according to the first aspect of the invention allows for the combination of a sensor and a lighting device having, for example, a signaling function. Indeed, the lighting device is configured to emit light beams, notably inwards and outwards from the vehicle. However, the light emission towards the interior of the vehicle, that is, towards the sensor positioned behind the lighting device, has very little impact on the sensor, thus ensuring its proper operation.

[0035] The lighting assembly according to the first aspect of the invention therefore makes it possible to add a light emission function to the sensor, while reducing the size of the lighting assembly present on board a motor vehicle.

[0036] Another aspect of the invention relates to a motor vehicle comprising a lighting assembly according to the first aspect of the invention.

[0037] In addition to the characteristics mentioned in the preceding paragraphs, the lighting assembly according to one aspect of the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations: - the lighting device is configured to perform a first signaling function; for example, the light source of the lighting device has a property corresponding to a first signaling function of a motor vehicle, said property associated with said first signaling function being the color and / or intensity of the light emitted by this source; this allows the lighting device to be used to perform a regulated signaling function without imposing any constraints on the shape or external appearance of the optical unit; - The first signaling function is selected from a group including: position light, daytime running light, brake light, direction indicator, and driving mode indicator; thanks to the characteristics of the flexible lighting device and transparent, it is possible to perform a wide variety of photometric signaling functions; - the lighting system comprises a plurality of light sources, each light source being configured to inject light into a different region of the light guide sheet; this arrangement is particularly suited to a light guide sheet with a large width; it also allows for light animations to be created by switching light sources on or off individually according to a predefined sequence; - the lighting device includes at least one light coupling element, the light coupling element being associated with said at least one light source so as to receive the light emitted by said corresponding light source and so as to transmit the received light to a region of the light guide sheet; the coupling element makes it possible to collect the maximum amount of light emitted by the light source, and thus to improve the efficiency of the lighting device; - according to one embodiment of the invention, the lighting device comprises at least two light coupling elements and at least two light sources, each light source being coupled to a respective light coupling element; furthermore, the light coupling elements are arranged so as to illuminate two different regions of the light guide sheet; for example, the light coupling elements are arranged on the same side of the guide sheet; - as an example, the light coupling element came from the material with the light guiding sheet; - the light guide sheet is fixed to the inner face of the transparent protective element using a transparent and flexible adhesive layer, said adhesive layer being positioned between the inner face of the transparent protective element and the outer surface of the light guide sheet; the adhesive layer makes it possible to fix the guide sheet to the inner face of the transparent protective element without altering the properties of the light emitted by the first light source and the second light source; - alternatively, the light guide sheet is overmolded onto the protective transparent element using a suitable injection process; - the area of ​​the outer surface of the light guiding sheet is equal to the area of ​​the inner face of the transparent protective element; - the area of ​​the outer surface of the light guide sheet is greater than the area of ​​the inner face of the transparent protective element; this allows the light coupling element to be arranged by the edge of the light guide sheet, the coupling element connecting the light guide sheet to the first light source; - the optical unit is configured to perform a second motor vehicle signaling function and / or a motor vehicle lighting function; of course, the optical unit and the lighting device are configured so that the presence of one does not disrupt the propagation or projection of light from the other when it is in operation; - the second signaling function associated with the optical unit is chosen from a group including: position light, daytime running light, stop light, direction indicator and driving mode indicator; - the lighting function associated with the optical unit is chosen from a group including: dipped beam, main beam and fog light; thanks to the fact that the optical unit is independent of the lighting device, the optical unit can provide a wide range of photometric functions; - the optical unit may include a light source of the type LED matrix; a light source of the type LED matrix allows for the implementation of adaptive lighting functions, for example by adapting the emission profile of the light source according to the presence of other vehicles on the road; - The lighting assembly is a front headlight of a motor vehicle, and the protective element and the lighting device together form a lens housing for the front headlight of the motor vehicle; in this example, the lighting device is mounted behind the protective element so that the protective element is the last element in the chain of the lighting assembly. In this way, the protective element, with its housing, isolates the headlight components from the external environment, thus protecting them; Furthermore, the light assembly can include both the optical unit and the sensor; - The lighting device of the lighting assembly described above is otherwise called the first lighting device; the lighting assembly further comprises a second lighting device, said second lighting device comprising: • a second transparent and flexible light guide comprising a second light guide sheet, said second light guide sheet: comprising an external surface and an internal surface opposite the external surface, the external surface of the second light guide sheet being fixed to the internal surface of the first light guide sheet; being configured to guide light by total internal reflection and to emit light towards the transparent protective element; • a second light source configured to inject the emitted light into a region of the second light guide layer, in which the first and second light devices are arranged so that the first and second guide layers overlap at least partially in the light assembly so as to project light through a common area of ​​the transparent protective element; thanks to the presence of a second light device arranged in contact with the first, it is possible to implement a second signaling or display function in addition to the function provided by the first light device. In this example, the second lighting device may have the same type of component as the first lighting device, namely a light source coupled with a light guide comprising a light-guiding mat. The light sources and light guides in both lighting devices may have the same dimensions and / or be made of the same material. However, the components of the second lighting device may differ from those of the first. luminous in terms of colour and / or intensity with regard to the light source, and in terms of the distribution and / or density of the decoupling elements arranged with regard to the light guide mat.

[0038] A second aspect of the invention relates to a motor vehicle comprising a lighting assembly according to the first aspect of the invention. BRIEF DESCRIPTION OF THE FIGURES

[0039] Other advantages and features of the invention will become apparent from the following description, illustrated by the figures in which: - Figure 1 represents an embodiment of a lighting assembly according to the first aspect of the invention; - Figure 2 represents another embodiment of a lighting assembly according to the first aspect of the invention; - Figure 3 represents a three-dimensional view of an embodiment of a lighting assembly according to the first aspect of the invention; - Figures 4 and 5 illustrate two embodiments of a lighting assembly according to the first aspect of the invention, the lighting assembly being positioned at the rear of a motor vehicle; - Figure 6 schematically shows the structure of a light guide mat; - Figure 7 illustrates one way of implementing a light guide; - Figures 8 and 9 show an example of a light coupling element coupling a light source to a light guiding sheet.

[0040] In the figures, identical elements are identified by identical references. For reasons of readability of the figures, the size scales between represented elements are not respected. DETAILED DESCRIPTION

[0041] Examples of the embodiment of a lighting system for a motor vehicle according to one aspect of the invention are described in detail below, with reference to the accompanying drawings. These examples illustrate the features and advantages of the invention. It should be noted, however, that the invention is not limited to these examples.

[0042] Figure 1 illustrates one embodiment of a light assembly 1 according to one aspect of the invention.

[0043] The lighting assembly 1, according to the embodiment illustrated in Figure 1, comprises: - a transparent protective element 10 delimited by an external face 10.1 and an internal face 10.2 opposite the external face; the transparent protective element is for example made of transparent polycarbonate and protects the luminous assembly 1 from the external environment while being transparent to light; - a luminous device 11 comprising a transparent and flexible light guide, said light guide comprising a light guide sheet 12; - a light source 13 configured to inject the emitted light inside the light guide mat 12; - an optical unit 14 adapted to emit light rays R towards the outside of the motor vehicle.

[0044] The light guide mat 12 comprises an external surface 12.1 and an internal surface 12.2 opposite the external surface 12.1. The guide mat 12 is adapted to guide light by total internal reflection and to emit light towards the transparent protective element 10 and thus towards the outside of the vehicle.

[0045] The optical unit 14 is positioned opposite the inner face 12.2 of the light guide mat 12. The light source 13 and the optical unit 14 are therefore independent and allow for the implementation of two different photometric functions. For example, the light source 13 can perform a first signaling function while the optical unit 14 can perform a second signaling function or a lighting function.

[0046] Because the light guide associated with the light source 13 is flexible and transparent, there are no constraints on the shape of the optical unit 14 that performs the secondary signaling or lighting function. This provides car manufacturers with considerable design freedom, allowing them to combine several functions in a single lighting assembly 1.

[0047] Figure 2 illustrates a second embodiment of a lighting assembly 2 according to a prior art. In the case shown in Figure 2, the lighting assembly 3 comprises: - a transparent protective element 10 delimited by an external face 10.1 and an internal face 10.2 opposite the external face; the transparent protective element is for example made of transparent polycarbonate and protects the light assembly 2 from the external environment while being transparent to light; - a lighting device 11 comprising a light guide, said light guide comprising a transparent and flexible light guide sheet 12; - a light source 13 configured to inject the emitted light inside the light guide mat 12; - a sensor 15 adapted to receive light beams R2 from outside the vehicle, the sensor 15 being positioned opposite the inner face 12.2 of the light guide mat 12.

[0048] The sensor 15 is adapted to receive light beams R2 coming from outside the vehicle and passing through the transparent protective element 10 and the transparent light guide mat 10.

[0049] Because the light guide mat 12 of the light device is configured to emit light towards the transparent protective element 10, the light emitted by the light device does not interfere with the sensor 15.

[0050] The sensor 15 could, for example, be a camera, an infrared camera, a radar, a lidar, or even a photodiode.

[0051] According to one embodiment, not shown in Figures 1 and 2, the light assembly 1 or 2 may comprise a plurality of light sources, each source being an independent light source. Each source is then configured to inject light into a different region of the light guide sheet 12. Furthermore, each source may be associated with a different photometric function, the light emitted by each light source having different characteristics. For example, each light source may emit light rays having characteristics corresponding to a different photometric function.

[0052] According to one embodiment, not illustrated in Figures 1 and 2, the lighting assembly may include a second lighting device, identical to the first lighting device included in the lighting assembly described with reference to Figures 1 and 2.

[0053] In particular, the second lighting device includes a second light guide comprising a second light guide sheet delimited by an external surface opposite the internal surface. The external surface of the second light guide sheet is fixed to the internal surface of the first light guide sheet, for example by means of a transparent and flexible adhesive layer.

[0054] Thanks to the presence of two lighting devices, each comprising a light guide strip and a light source, it is possible to increase the functions display and / or signaling provided by the light assembly according to a first aspect of the invention.

[0055] Figure 3 illustrates a three-dimensional representation of a lighting assembly 1 according to an embodiment of the first aspect of the invention. As illustrated in Figure 1, the lighting assembly 1 comprises the lighting device 11 provided with a light guide including a flexible and transparent light guide sheet 12 and a light source (not visible in Figure 3) associated with the light guide and adapted to inject light rays into the guide sheet 12.

[0056] In the light assembly illustrated in Figure 3, the light device 11 also includes a light coupling element (not visible in Figure 3) arranged between the light source and the light guide mat 12 to transmit the light emitted by the light source to the mat 12. An example of the light coupling element will be shown later in the description with Figures 6 and 7 as supporting examples.

[0057] Here, the sheet 12 and the transparent protective element 10 are held within a frame 16 that grips the peripheral edges of these elements. The frame 16 has grooves that form a housing for the light coupling element and the light source. Designed in this way, the frame 16 conceals the coupling element and the light source, thus improving the aesthetic appearance of the lighting device.

[0058] The light assembly 1 illustrated in Figure 3 further includes an optical unit 14 positioned inside the motor vehicle and opposite the inner surface 12.2 of the guide mat 12. The optical unit 14 is adapted to emit light rays passing through the guide mat 12 towards the outside of the vehicle.

[0059] Figure 3 illustrates how the light emitted by the optical unit 14 passes through the transparent and flexible light guide sheet 12 without the shape or function of the optical unit 14 being modified by the presence of the lighting device comprising the light guide sheet 12. In other words, the lighting device comprising the light guide sheet 12 does not impose any constraints on the shape or function of the optical unit 14.

[0060] Figure 4 illustrates an example of a light assembly 4 comprising an optical unit 14 and used in a rear light of a motor vehicle. In the case illustrated in Figure 4, the light source has a rear position light function and the optical unit has a brake light and position indicator function. Figure 4 illustrates in particular the external appearance of the light assembly 4 for three different operating modes of the device.

[0061] The light panel 40 illustrates the external appearance of the light assembly 4 when only the light source is illuminated. In this case, the light device of this assembly 4 appears as a homogeneous luminous surface of constant intensity and typically red in color. To achieve this, the light guide mat includes a plurality of light decoupling elements that are evenly distributed across its entire surface. Furthermore, the light source used emits red light.

[0062] The illuminated panel 41 illustrates the appearance of device 1 when the vehicle is braking and the optical unit is thus activated. In this case, the illuminated assembly 4 appears as a homogeneous luminous surface with three parallel bands 41A of constant intensity and a color different from that displayed by the light guide strip, typically dark red. It is evident how, thanks to this embodiment of the illuminated assembly 4, it is possible to obtain a specific effect for the brake light signaling function, without this effect being altered by the presence of the position light signaling function in the same illuminated assembly.

[0063] Finally, the illuminated panel 42 illustrates the external appearance of the light assembly 4 when the turn signal is activated by switching on the optical unit. The displayed geometric pattern, the three bands 42A, is the same as for the brake light function, this pattern being associated with the shape of the optical unit. However, in this case, the intensity of the three bands 42A is flashing, typically yellow or orange. In this case, the optical unit comprises multiple light sources, these sources emitting different colors and being controlled independently.

[0064] The example illustrated in Figure 4 shows how, by using the light assembly according to one aspect of the invention, it is possible to combine three different signaling functions while leaving a great deal of design freedom regarding the external appearance and shape of the signaling devices.

[0065] Figure 5 illustrates an example of a lighting assembly 5 comprising an optical unit and used in a rear light of a motor vehicle. As in the case of Figure 4, the light source provides the function of a rear position light. The optical unit provides the function of a brake light.

[0066] The illuminated panel 50 shows the exterior appearance of the lighting assembly when only the light source is illuminated, displaying a uniform illuminated surface, typically red. The illuminated panel 51 shows the exterior appearance of the lighting assembly during vehicle braking when the optical unit is also activated. In addition to the uniform illuminated surface, a pattern 51A is now displayed with a constant light intensity.

[0067] The examples illustrated in figures 4 and 5 demonstrate how the shape of the first signaling function and that of the second signaling function are completely independent, the lighting device imposing no constraints on the appearance of the second light source.

[0068] An example of a light guide used in a lighting assembly according to one aspect of the invention is illustrated in Figure 6. The light guide as illustrated in Figure 6 comprises a transparent and flexible light guide sheet 12 adapted to receive light rays through a light injection slice 114 and to reflect the light rays in a direction x substantially normal to a surface of the flexible guide sheet which thus extends in a yz plane in Figure 6. The directions x, y and z are defined with respect to the frame illustrated in Figure 6.

[0069] A guide sheet is defined as an optical guiding element in which one dimension is significantly smaller than the other two dimensions in space. Here, we consider a flexible guide sheet whose thickness along the x-axis, that is, the distance between the outer and inner surfaces, is at least two orders of magnitude smaller than its dimensions along the yz plane in which the flexible guide sheet extends. For example, the guide sheet has a thickness along the x-axis of between 200 and 1000 micrometers and extends over several centimeters in the y and z directions.

[0070] The flexible guide sheet 12 may include a flexible film 121 at its core, comprising the light injection slice 114. The flexible film further includes a set of microstructures 113 adapted to reflect the light rays guided in the flexible film 111 out of the flexible guide sheet 12, in particular in one or more directions substantially along the x-axis. In the example illustrated in Figure 6, the light rays emerge in the 4-x direction with the orientation shown in the figure. For example, the light rays are emitted outwards from the front of a vehicle.

[0071] The flexible guide sheet 12 may further include one or two optional protective layers 122 and 123, which provide mechanical protection for the flexible film 111.

[0072] Furthermore, the propagation of light rays in the flexible film 121 is done by total internal reflection thanks to the difference between the refractive index of the flexible film 121 and that of a layer of glue or adhesive applied to at least one face of the flexible film.

[0073] As illustrated, the flexible film 121 is bonded to the protective layers 122 and 123. Specifically, a layer of adhesive is applied between the flexible film and each protective layer, on both sides of the film, to ensure the protective layers adhere to the film.

[0074] The chosen adhesive is transparent and has a different refractive index than the flexible film, thus enabling total internal reflection within the flexible film 121. In other words, due to the difference in refractive index, light rays propagating within the flexible film undergo total internal reflection upon encountering the interface between the flexible film and the adhesive layer at an angle of incidence less than normal. Therefore, the guiding sheet is capable of guiding light by total internal reflection, for example, from an input zone, here slice 114, to an output zone.

[0075] Figure 7 illustrates another view of a lighting device used in a lighting assembly according to one aspect of the invention. The flexible guide sheet 12, or more precisely the flexible film 121, may include a mixing zone 111.2 and several regions 111.1, each region comprising a light-emitting zone provided with light-extraction elements capable of reflecting the light rays guided in the flexible film away from the flexible and transparent guide sheet 12, in particular in one or more directions substantially along the x-axis. In a lighting device used in a lighting assembly according to one aspect of the invention, the light extracted from the guide sheet 12 is reflected towards the transparent protective element 10 and thus towards the outside of the vehicle.

[0076] The mixing zone 111.2 is positioned upstream of the light emission zone, following the direction of light ray propagation within the light guide sheet 12. The light injected into the light guide sheet 12 via the slice 114 will be mixed in the light mixing region 111.2 to obtain better luminous homogeneity. The light then propagates into the different regions, or precisely into the light emission zones 111.1 through which the light emerges from the light guide sheet 12 in the x direction. Thus, when a region receives light, the light emission zone reflects light outwards and displays a luminous pattern.

[0077] As an example, the light extraction elements 113 can be microstructures 113 etched into the flexible film 111. In the following description, the microstructures 113 are cited as an example of the light extraction elements 113.

[0078] The light guide according to the embodiment illustrated in Figure 7 further includes at least one light coupling element 102.

[0079] A light coupling element 102 comprises several strips 102.1 cut from the guide sheet. For example, it comprises between three and ten strips 102.1. In the example in Figure 7, the light guide comprises a light coupling element 102 with ten elements 102.1. The coupling element 102 injects light into the guide sheet 12, specifically into the region 111.1.

[0080] It should be noted that during the manufacturing process of the light guide, the strips 102.1 and the light guide sheet 110 are made from a large raw sheet which is sheared at one end to separate the different strips 102.1 along the y-axis illustrated in Figure 7, thus forming the different light injection elements. The strips 102.1 therefore remain attached to the light guide sheet 12 at one end. Shearing the raw sheet means cutting all the layers within the raw sheet to form parallel strips that constitute the light injection strips 102.1.

[0081] Thanks to a folding element (not shown in the figures) contained in the light guide, each strip is folded to form a stack as shown in Figure 8 and Figure 9.

[0082] Indeed, as illustrated in Figure 8, each light injection band 102.1 is composed of: - a main part 102.12 which is cut from the light guide mat and extends from the light guide mat, and - a terminal part 102.13 which extends along the z-axis.

[0083] The terminal section 102.13 is connected to the light guide mat 110 by means of the main section 102.12. The main sections 102.12 and the terminal section 102.13 are divided by a fold 102.14 at a bending element not shown in Figure 8. The end portion 102.13 extends beyond the fold 102.14. The fold 102.14 has a non-zero radius of curvature, which allows light to propagate. Figure 8 illustrates the end portions 102.13, the main portions 102.12 of the light injection bands 102.1 of a light coupling element 102, and the fold 102.14 that separates them. The total length of a light injection waveguide 102.1 is the sum of the lengths of the main portion 102.12 and the end portion 102.13.

[0084] As illustrated in Figure 9, the strips 102.1 of a group 102 are folded so that their end portions 102.13 form a stack 124 with thickness E adapted to an emission surface of the light source 20. The thickness E is the sum of the thicknesses e of each strip 102.1 whose end portions 102.13 form the stack 124. The stack 124 includes an entrance surface 124.1 formed by the ends of the end portions 102.13 of each of the light injection elements 102.1 of the group 102.

[0085] The light coupling element 102 is coupled with at least one light source 13 so as to receive the light rays R emitted by said source in each of the light injection elements.

[0086] Since the light injection elements are made of material along with the light-guiding sheet, the light rays R will propagate by total internal reflection in the bands e 102.1 of group 102, thus bringing light to the light-guiding sheet 12, which is adjacent to and attached to the bands 102.1, and will therefore illuminate the region of the light-guiding sheet 12. The length of the light injection elements forming part of the light coupling element 102 can be dimensioned to obtain a desired length for the coupling element 102. For example, the coupling element 102 can be lengthened to position the light source far from the light-guiding sheet to prevent overheating of this sheet and to promote heat dissipation from the source.Indeed, the light source coupled to the coupling element can be relocated away from the light guide mat, placing it in a less confined space and thus overcoming space limitations. This allows for a sufficiently large electronic support to accommodate a heat sink of appropriate size to cool the remote light source.

[0087] The description of the invention is not limited to the embodiments described above. Thus, other modifications and improvements may be envisaged, it being understood that they form part of the scope of the invention.

Claims

Claims

1. Motor vehicle lighting assembly (1; 2; 4; 5) comprising: - A protective element (10) comprising an external face (10.1) and an internal face (10.2) opposite the external face; - A light device (11) comprising: • a light guide comprising a light guide sheet (12), said light guide sheet (12) comprising an external surface (12.1) and an internal surface (12.2) opposite the external surface, said external surface (12.1) being fixed to the internal face (10.2) of the protective element (10); • at least one light source (13) adapted to inject light into a region of the light guide sheet; - An optical unit (14) configured to perform at least one photometric function of a motor vehicle and / or a sensor positioned opposite the internal surface (12.2) of the light guide sheet (12) characterized in that: - the protective element (10) is transparent so as to allow light rays emitted by the optical unit (14) to pass through when the latter is in operation to perform a photometric function of a motor vehicle; - the light guide sheet (12) is flexible so that it can be deformed when mounting the lighting device (11) in the lighting assembly; - the light guide sheet (12) has a degree of transparency similar to that of the protective element (10); and - the guide sheet is configured to guide the light by total internal reflection and to emit the light towards the transparent protective element (10).

2. A light assembly (1, 2) according to claim 1, wherein the light device (11) is spatially separated from the optical unit (14) and / or the sensor, which are positioned opposite the inner surface of the light guide sheet.

3. A light assembly (1,2) according to claim 1 or claim 2, wherein the light device is configured to perform a first signaling function.

4. A light assembly (1; 2; 4; 5) according to one of the preceding claims, wherein the light device comprises a plurality of light sources (13), each light source being configured to inject light into a different region of the light guide sheet (12).

5. A light assembly (1; 2; 4; 5) according to one of the preceding claims, wherein the light device (11) comprises a light coupling element (102), the light coupling element (102) being associated with said at least one light source so as to receive the light emitted by said corresponding light source and so as to transmit the received light to a region of the light guide sheet (12).

6. Light assembly (1; 2; 4; 5) according to the preceding claim, wherein said light coupling element (102) is integral with the light guide sheet.

7. Light assembly (1; 2; 4; 5) according to one of the preceding claims in which the light guide sheet (12) is fixed to the internal face (10.2) of the transparent protective element (10) using a transparent and flexible adhesive layer, said adhesive layer being positioned between the internal face of the transparent protective element and the external surface (12.1) of the light guide sheet (12).

8. Light assembly (1; 2; 4; 5) according to one of the preceding claims in which the area of ​​the outer surface (12.1) of the light guide sheet (12) is greater than the area of ​​the inner face (10.2) of the transparent protective element (10).

9. Light assembly (1; 4; 5) according to one of the preceding claims, wherein the optical unit (14) is configured to perform a second motor vehicle signaling function and / or a motor vehicle lighting function.

10. Light assembly (1; 4; 5) according to the preceding claim in which: - the second signaling function associated with the optical unit (14) is chosen from a group comprising: position light, daytime running light, brake light, direction indicator and driving mode indicator; and / or - the lighting function associated with the optical unit is chosen from a group including: low beam, high beam and fog light.

11. Lighting assembly (1; 2) according to one of the preceding claims, in which the lighting assembly is a motor vehicle front headlight and the assembly of the protective element (10) and the lighting device (11) forms a closing glass for the motor vehicle front headlight.

12. A light assembly (1; 2; 4; 5) according to one of the preceding claims, wherein the light device (11) is a first light device and wherein the light assembly further comprises a second light device, said second light device comprising: - a second transparent and flexible light guide comprising a second light guide sheet, said second light guide sheet: • comprising an outer surface and an inner surface opposite the outer surface, the outer surface of the second light guide sheet being attached to the inner surface of the first light guide sheet; • being configured to guide the light by total internal reflection and to emit the light towards the transparent protective element; - a second light source configured to inject the emitted light into a region of the second light guide sheet in which the first and second light devices are arranged such that the first and second guide sheets are at least partially superimposed in the light assembly so as to project light through a common area of ​​the transparent protective element.

13. Motor vehicle comprising a light assembly (1; 2) according to one of the preceding claims.

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