Light device for a motor vehicle configured to project an image onto a projection surface

Abstract

The invention relates to a light device (2) for a motor vehicle (1), the light device (2) being configured to project an image (Im) with at least one fixed-contour lighting zone onto a surface (3) located around the vehicle (1) or onto a surface (3) located inside a passenger compartment of the vehicle (1), the light device (2) being characterised in that it comprises: • at least one light source (4) configured to produce a monochromatic light beam (F); • at least one optical device (14) juxtaposed with the light source (4) such that the light beam (F) passes through the optical device (14), the optical device (14) comprising at least one meta lens (15) configured to modify at least one property of the wavefront of the light beam (F) so as to orient the light beam (F) in a propagation direction.

Description

Luminous device for a motor vehicle configured to project an image onto a projection surface.

[0001] The present invention relates to a lighting device for a motor vehicle, the lighting device being configured to project an image with at least one lighting zone with fixed contours onto a projection surface located around the vehicle or located inside a passenger compartment of the vehicle. The invention also relates to a motor vehicle equipped with such a lighting device.

[0002] Some motor vehicles include one or more signal lamps that are equipped with one or more lighting devices configured to project an image with at least one lighting zone with fixed contours onto the ground in the vicinity of a vehicle for orientation or maneuvering functions. These lighting zones may include images and / or patterns such as arrows, lines or pictograms. Such lighting devices are intended to display useful information to the driver and / or other road users. Publication WO2016184721A1 discloses such a lighting device.

[0003] Furthermore, some motor vehicles are equipped with a lighting device configured to project an image onto the ground around the vehicle, for example at the front of the vehicle or on the sides of the vehicle, in particular at the doors, to provide information facilitating or guiding the exit of a passenger from said vehicle, in particular when the ambient light is relatively low. These images may include patterns such as arrows, lines or pictograms. Such lighting devices may also aim to display information useful to other road users. These lighting devices thus make it possible to communicate the intentions of the driver of the motor vehicle to other road users and in particular to pedestrians. Publication EP3401161A2 discloses such a lighting device.

[0004] Finally, there are fixed or portable lighting devices that allow an image to be projected onto a surface located inside a motor vehicle interior, and in particular onto the roof of the interior. In particular, there are small projection lamps that are equipped with a light source, such as a light-emitting diode for example, and a mask pierced with a multitude of openings.

[0005] There are also digital dynamic projection systems such as micro-mirror matrices (called "DMD" for "digital micromirror device"), microelectromechanical systems (called "MEMS" for "microelectromechanical systems"), microLEDs, liquid crystal displays or even LCOS video projectors.

[0006] The light devices known from the state of the art are generally complex to manufacture and use.

[0007] In addition, the lighting devices known from the state of the art are generally heavy and bulky, which complicates their integration within a motor vehicle. Their discreet integration into a vehicle, without altering its aesthetic appearance, is therefore difficult to achieve.

[0008] Furthermore, when light devices use a mask, such a mask limits the transmitted light power, which results in limited light intensity.

[0009] Furthermore, some lighting devices known from the state of the art include relatively fragile components that can be damaged, fail, or even break if they are exposed to these shocks or if the motor vehicle is used in a rough environment (damaged, dusty, dirty road or other). The vibrations generated then prove very problematic because they bring significant limitations when projecting images. Presentation of the invention

[0010] The objective of the present invention is to provide a vehicle lighting device which overcomes at least one of the drawbacks mentioned above.

[0011] In particular, the lighting device according to the invention aims to be light, compact and configured to simply project an image with at least one lighting zone with fixed contours onto a projection surface located around the vehicle or located inside a passenger compartment of the vehicle.

[0012] Thus, a first object of the invention is a light device that is simple to manufacture and configured to project an image with at least one lighting zone with fixed contours, of quality with high luminous efficiency.

[0013] A second object of the invention is a more compact lighting device, easily integrated into a motor vehicle.

[0014] A third object of the invention is a lighting device which is not affected by possible shocks and / or vibrations generated by the use of the motor vehicle in which said lighting device is integrated.

[0015] The invention relates to a lighting device for a motor vehicle, the lighting device being configured to project an image with at least one lighting zone with fixed contours onto a projection surface located around the vehicle or onto a surface located inside a passenger compartment of the vehicle, the lighting device being characterized in that it comprises: at least one light source configured to produce a monochromatic light beam; at least one optical device juxtaposed with the light source so that the light beam passes through the optical device, said optical device comprising at least one meta-lens configured to modify at least one property of the wavefront of the light beam so as to orient the light beam in a propagation direction.

[0016] According to non-limiting embodiments, said light device may further comprise one or more additional characteristics taken alone or in all technically possible combinations, among the following.

[0017] According to a non-limiting embodiment, the meta-lens of the optical device comprises at least one nanostructure configured to modify the amplitude and / or the phase of the light beam produced by the light source and passing through the optical device so as to influence the orientation of the light beam at the exit of the meta-lens.

[0018] According to a non-limiting embodiment, the nanostructure of the meta-lens is configured to influence the orientation of the light beam at the exit of the meta-lens so that the light device emits a conical-shaped light beam in a projection direction inclined at an angle of between 30° and 90° relative to the direction of propagation of the light beam produced by the light source.

[0019] According to a non-limiting embodiment, said light device further comprises a liquid crystal layer arranged between said at least one meta-lens and said at least one light source and configured to take at least two states including: - an inactive state where the liquid crystal layer is inactive in order to preserve the optical properties of the incident light beam and allow said at least one meta-lens to obtain a first convergence zone of the light beam on the projection surface, - an active state where the liquid crystal layer is active in order to modify the optical properties of the incident light beam and allow said at least one meta-lens to obtain a second convergence zone of the light beam on the projection surface.

[0020] According to a non-limiting embodiment, the optical properties of the incident light beam are a phase and a polarization.

[0021] According to a non-limiting embodiment, the light device comprises a multitude of light sources and a multitude of meta-lenses.

[0022] According to a non-limiting embodiment, said light device comprises at least one set of three light sources juxtaposed next to each other and at least one stack of three meta-lenses arranged opposite said set, each light source being configured to emit light of a different color from the other light sources of said at least one set, and the three meta-lenses being designed to be tuned to different wavelengths.

[0023] According to a non-limiting embodiment, each light source is associated with a meta-lens which is specific to it.

[0024] According to a non-limiting embodiment, the multitude of meta-lenses are arranged in rows and columns on the optical device so as to form a matrix, and the multitude of light sources are also arranged in rows and columns to form a matrix so that each light beam produced by one of the light sources passes through the meta-lens with which said light source is associated.

[0025] According to a non-limiting embodiment, said light device comprises at least three sets of light sources juxtaposed next to each other and at least three sets of corresponding meta-lenses juxtaposed next to each other, each set of light sources being configured to emit monochromatic light of a different color from the other sets.

[0026] According to a non-limiting embodiment, each of the three sets of light sources comprises three light sources, and each of the three sets of meta-lenses comprises three meta-lenses.

[0027] According to a non-limiting embodiment, said light device comprises at least three sets of light sources juxtaposed next to each other and at least three sets of corresponding meta-lenses juxtaposed next to each other, each light source of each set being configured to emit a monochromatic light of a different color from the other light sources of the same set.

[0028] According to a non-limiting embodiment, each of the three sets of light sources comprises three light sources, and each of the three sets of meta-lenses comprises three meta-lenses.

[0029] According to a non-limiting embodiment, said image comprises lighting zones and shadow zones, the lighting zones being those towards which the light beam of said at least one light source is oriented with maximum light transmission.

[0030] According to a non-limiting embodiment, the light device further comprises a projection optic configured to shape the light beam and to direct said light beam towards said surface.

[0031] The invention also relates to a motor vehicle comprising a lighting device according to any one of the preceding claims. Presentation of figures

[0032] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of different particular embodiments made without limitation in relation to the attached figures among which:

[0033] This is a schematic view of a motor vehicle equipped with a first lighting device according to the state of the art.

[0034] This is a schematic view of a motor vehicle equipped with a second lighting device according to the state of the art.

[0035] This is a schematic view of a motor vehicle equipped with a third lighting device according to the state of the art.

[0036] This is a schematic view of a motor vehicle equipped with a light device according to a non-limiting embodiment of the invention, said light device comprising a plurality of light sources and an optical device according to a first non-limiting embodiment, and being configured to project an image onto a surface located around the vehicle.

[0037] This is a schematic view of a motor vehicle equipped with a lighting device according to a non-limiting embodiment of the invention, said lighting device comprising a plurality of light sources and an optical device according to a first non-limiting embodiment, and being configured to project an image onto a surface located inside the vehicle.

[0038] This is a schematic view of an optical device of the light device of the or of the according to a first non-limiting embodiment of the invention.

[0039] This is a schematic perspective view of a detail of a nanostructure of a meta-lens of the optical device of the or of the.

[0040] This is another schematic view of a detail of a nanostructure of a meta-lens of the optical device of the or of the.

[0041] The is a schematic perspective view of a meta-lens of the optical device of the or of the associated with a layer of liquid crystals forming a variable focal length lens.

[0042] This is a schematic view of a motor vehicle equipped with a light device 2b or 2b according to a first non-limiting embodiment of the invention.

[0043] Illustrates a greatly enlarged view of a non-limiting embodiment of a single nanopillar of a meta-lens of the optical device of the or of the with a portion of a substrate.

[0044] Illustrates an enlarged view of a non-limiting embodiment of a plurality of nanopillars of a meta-lens of the optical device of the or of the according to a non-limiting embodiment.

[0045] Laillustrates a first curve indicating a phase variation as a function of the radius of a nano-pillar of a meta-lens of the optical device of the or of the.

[0046] Laillustrates a second curve indicating a variation of light transmission as a function of the radius of a nano-pillar of a meta-lens of the optical device of the or of the.

[0047] Schematically illustrates the light device 2b configured to project a light image onto a plane parallel to a substrate of a meta-lens of the optical device of the light device.

[0048] Schematically illustrates the light device of Figures 2a or 2b configured to project a light image onto a plane non-parallel to a substrate of a meta-lens of the optical device of the light device.

[0049] Schematically illustrates the lighting device further comprising a projection optic according to a non-limiting embodiment, the projection optic being configured to project a light image onto the ground.

[0050] Theis a perspective view of the light device of the, said light device further comprising a housing and a cover.

[0051] Schematically illustrates the lighting device of figures 2a or 2b according to a first non-limiting variant embodiment, said lighting device comprising three sets of light sources side by side and an optical device comprising three sets of meta-lenses side by side.

[0052] Schematically illustrates the lighting device of figures 2a or 2b according to a second non-limiting variant embodiment, said lighting device comprising three sets of three light sources and an optical device comprising three sets of meta-lenses side by side.

[0053] This is a schematic view of a motor vehicle equipped with a light device according to a non-limiting embodiment of the invention, said light device comprising a plurality of light sources and an optical device according to a second non-limiting embodiment, and being configured to project an image onto a surface located inside the vehicle.

[0054] Diagrammatically illustrates a motor vehicle equipped with a lighting device according to the invention, said lighting device making it possible to project a static image onto the ground which is a logo.

[0055] Diagrammatically illustrates a non-limiting example of three images making it possible to produce dynamic luminous signage, the three images being formed by three meta-lenses of the luminous device of figures 2a or 2b or of the. Detailed description

[0056] A first embodiment of a motor vehicle 1' according to the state of the art is described below with reference to the purpose of signaling an orientation or maneuvering function.

[0057] The vehicle 1' illustrated schematically on the figure comprises a light device 2' according to an embodiment known from the state of the art.

[0058] This light device 2' comprises at least one light source 4' capable of producing a light beam F' and a lens matrix 6' intended to be traversed by the light beam F', as well as a light parallelization unit 8'. This light parallelization unit 8' is positioned on the path of the light beam F' between the light source 4' and the lens matrix 6'. The parallelization unit 8' is in the form of a lens which is configured to parallelize the light beam F' emitted by the light source 14' in the main emission direction which is substantially parallel to the optical axes of the microlenses of the matrix 6'.

[0059] The lens array 6' comprises a plurality of pairs of microlenses 10' distributed over a flat surface perpendicular to the optical axes of the lenses of this array 6'. Each pair of microlenses 10' comprises an upstream microlens and a downstream microlens. By convention, the expression "upstream microlens" designates the microlens through which the light beam F' passes first, while the expression "downstream microlens" designates the microlens through which the light beam F' passes second. In other words, the light beam F' from the light source 4' first passes through the parallelization unit 8', then the microlens upstream of a pair of microlenses 10' arranged within the array 6' and finally the microlens downstream of this same pair of microlenses 10'.

[0060] This embodiment of the light device 2' known from the state of the art has several drawbacks. In particular, a large number of microlenses are required to manufacture such a light device 2', which makes it bulky and cumbersome in addition to significantly increasing its weight.

[0061] Furthermore, an optical axis of the downstream microlens must be coaxial with respect to an optical axis of the upstream microlens of the same pair of microlenses 10', which requires great precision when placing the microlenses 10' in the matrix 6', which can be time-consuming and costly. The risk that this alignment of the optical axes of the microlenses 10' of the same pair is disrupted following vibrations due to the use of the vehicle 1' or following an impact on the lighting device 2' is not negligible.

[0062] A second embodiment of a motor vehicle 1' according to the state of the art is described below with reference to producing static or dynamic luminous signage around the vehicle.

[0063] The vehicle 1' illustrated schematically on the figure comprises a light device 2' according to an embodiment known from the state of the art. The light device 2' is configured to project an image onto the ground 3', at the front of the vehicle 1. It is specified that the front designates the side of the vehicle 1' towards which it is heading in a straight line, when moving forward.

[0064] In this embodiment known from the state of the art, the light device 2' comprises at least one light source 4', capable of producing a light beam F', and a mask 5' positioned on the path of the light beam F'. Said at least one light source 4' is a monochromatic light source. The light from such a light source 4' only comprises rays of a single wavelength; that is to say, it only comprises light rays having a specific color.

[0065] The surface of the mask 5' comprises opaque zones 8' and transparent zones 9', these transparent zones 9' generally having a shape suitable for the projection of an image comprising a pattern. The mask 5' therefore makes it possible to modify the light beam F' coming from the light source 4' so as to project an image comprising a pattern onto the ground 3' in front of a vehicle 1'. An optical element 11', such as a projection lens, may be provided downstream of the mask 5', in order to shape and direct the light beam F' towards the ground 3'. In this way, the light rays incident at the transparent zone 9' of the mask 5 pass through the mask 5' and are then guided towards the ground 3' by the optical element 11'.

[0066] This embodiment known from the state of the art has several drawbacks. In particular, the transparent zone(s) are generally positioned at the edge of the mask 5', leaving a central zone of the mask 5' unused, except for the part of the mask 5' mechanically connected to an actuation means 12' which makes it possible to rotate the mask around an axis of rotation. The mask 5' is thus rotatable so as to produce an animated image. It is therefore necessary to find a compromise between the number of transparent zones 9' suitable for projecting an image and the size of said transparent zones 9'.

[0067] In addition, the actuating means 12' and / or its mechanical connection with the mask 5' may be subject to shocks or vibrations during use of the motor vehicle 1', which may cause a disturbance in the position of the mask 5'. Such a disturbance of the mask 5' may result in a faulty projection of the images onto the ground 3', which may inconvenience the driver of the vehicle 1'. For example, the animated image may appear to be jumping.

[0068] Furthermore, the order of projection of the images onto the ground 3' depends on the arrangement of the transparent areas 9' on the mask 5'. More particularly, only images that are adjacent to each other on the mask 5' can be projected consecutively onto the ground. In other words, arranging transparent areas 9' with patterns and / or contours on the edge of the mask 5' greatly limits the options for the order of projection of said images onto the ground 3'.

[0069] Finally, the 5' mask, which works by absorbing light, blocks some of the light, about 50% of the light. The luminous efficiency of such a 2' light device is therefore reduced.

[0070] A third embodiment of a motor vehicle 100' according to the state of the art is described below with reference to producing a design inside the passenger compartment of the motor vehicle 100'.

[0071] In the, the vehicle 100' comprises a lighting device 2' according to an embodiment known from the state of the art. The lighting device 2' is configured to project an image onto a surface 3' inside the passenger compartment 10' of the vehicle 100'. In the specific case illustrated in the, the surface 3' onto which the lighting device 2' projects an image is the roof of the passenger compartment 10' of the vehicle 100' and more precisely the interior trim of the roof of the body of the motor vehicle 100'.

[0072] In this embodiment known from the state of the art, the light device 2' comprises at least one light source 4' capable of producing a light beam F' and a mask 5' positioned on the path of the light beam F'. Said at least one light source 4' is a monochromatic light source. The light from such a light source 4 only comprises rays of a single color; it only emits light rays having a specific wavelength or a wavelength included in a specific interval. The mask 5' may take the form of a cup or a dome arranged above the light source 4', as illustrated in the, and may at least partially encompass the light source 4'.

[0073] The mask 5' has one or more openings 6' configured to allow a portion of the light beam F' to pass through so as to project one or more light points onto the target surface 3'. Each opening 6' may comprise an optical element 7', such as a projection lens, in order to shape and direct the light beam F' towards the surface 3'.

[0074] In the case where the dome- or cup-shaped mask 5' is mobile, the light device 2' comprises an actuating means 8' mechanically connected to the mask 5' to rotate it around an axis of revolution of said dome. Thus, the set of points projected by the light device 2' onto the surface 3' of the passenger compartment 10' appears mobile, so that an observer sees light points moving on the surface 3' of the passenger compartment 10' inside the motor vehicle 100'.

[0075] This embodiment known from the state of the art has several drawbacks. In particular, such a mask 5' does not allow quality images to be projected when these have complex shapes. Indeed, in the case where the surface 3' inside the motor vehicle 1' is not flat, but curved, this can induce a distortion of the images on said surface 3'. Furthermore, the contours of any patterns projected by the light device 2' known from the state of the art onto the surface 3' can be blurred and imprecise, which can harm the quality of the image.

[0076] In addition, the actuating means 8' and / or its mechanical connection with the mask 5' may be subject to shocks or vibrations during use of the motor vehicle 100', which may cause a disturbance in the position of the lighting device 2'. Such a disturbance may result in faulty projection of the images in the passenger compartment, which may disturb the driver and / or any passengers of the vehicle 100'. The images may in fact be shifted due to the vibrations.

[0077] Finally, the 5' mask cuts off some of the light, about 50% of the light. The luminous efficiency of such a 2' light device is therefore low.

[0078] An embodiment of a motor vehicle 1 according to the invention is described below with reference to Figures 2a to 18. Throughout the description, the motor vehicle 1 is a motor vehicle of any type, in particular a passenger vehicle, a utility vehicle, a truck or even a bus. In the remainder of the description, the motor vehicle 1 is otherwise referred to as vehicle 1.

[0079] This embodiment aims to provide a solution to the problems identified with the known embodiment of the prior art by remedying at least one of the drawbacks described above and by proposing an improved lighting device 2.

[0080] The light device 2 is configured to:- signal an orientation or maneuvering function,- produce static or dynamic light signage around (near) the vehicle, or- produce a light image.

[0081] The lighting device 2 is configured to project at least one image Im with at least one lighting zone (described later) onto a surface 3 located around the vehicle 1 or located inside the passenger compartment 10 of the vehicle 1. In the remainder of the description, a lighting zone is otherwise called an illuminated zone.

[0082] In non-limiting embodiments, the surface 3 is: - the ground of the road on which the vehicle 1 is located, - a surface 3 inside the passenger compartment of the vehicle 1.

[0083] In non-limiting examples, surface 3 inside the passenger compartment of the vehicle 1 is the dashboard of the vehicle 1 or the ceiling of the vehicle 1.

[0084] In a non-limiting embodiment, the surface 3 is curved.

[0085] The orientation or maneuvering function is a function performed during the night or the day. In a non-limiting embodiment, the signaling of this orientation or maneuvering function is so-called extended signaling, otherwise called extended signaling function called in English "Extended Signaling". The signaling of an orientation or maneuvering function comprises the projection on the ground of a static Im image on the ground.

[0086] The extended signaling function allows the synchronization of an image projected on the ground with a traditional signaling function such as an orientation or maneuvering function. In non-limiting examples, the orientation function is a turn signal for changing lanes, the maneuvering function is a reversing light for parking or a brake light.

[0087] In a non-limiting example, the image Im is projected onto the ground by synchronizing with the vehicle's turn signal. It therefore appears and disappears at regular intervals. Thus, when the driver of the vehicle 1 activates the turn signal, the extended signaling function amounts to projecting an image onto the ground so that people on the periphery of the vehicle 1 have the information that the vehicle 1 is turning right or left. This is of interest to any third party (a pedestrian, a cyclist, etc.) who does not see the turn signal of the vehicle 1. The image Im is thus synchronized by appearing on the ground when the turn signal comes on and disappearing from the ground when the turn signal goes off.

[0088] In another non-limiting example, the image Im projected on the ground is a static pattern which relates to a maneuvering function which is the reversing light of the vehicle 1 for parking.

[0089] In non-limiting examples, the production of static or dynamic luminous signage around the vehicle is: - a welcome scenario function called in English "Welcome Scenario". The welcome scenario function may include dynamic signage around the vehicle called in English dynamic called in English "dynamic carpet projection" according to which an animated image is projected. The animated image is thus formed of several Im images. - static signage called in English "static carpet projection" according to which a fixed Im image is projected.

[0090] The production of a luminous image makes it possible to display an image on a surface 3 inside the passenger compartment 10 of the vehicle 1. In a non-limiting example, the luminous image Im is displayed on the dashboard of the vehicle 1.

[0091] When the light device 2 is configured to signal an orientation or maneuvering function, in non-limiting embodiments, it may be, for example, arranged at the front of the vehicle 1, at the level of a grille and / or at the level of headlights intended to illuminate the road and to make the vehicle 1 clearly visible to other road users. Alternatively, the light device 2 may be arranged on the sides of the motor vehicle 1 or at the rear of said vehicle 1. When it is arranged on the sides of the vehicle 1, it may be at the level of an exterior rearview mirror. When it is arranged at the rear of the vehicle 1, it may be at the level of the rear lights. It is specified that the front designates the side of the vehicle 1 towards which it is heading in a straight line, in forward motion.

[0092] When the light device 2 is configured to produce static or dynamic light signage around the vehicle 1, in a non-limiting embodiment, it can be arranged on one of the sides of the vehicle 1. When it is arranged on one of the sides of the vehicle 1, it can be arranged at the level of an exterior rearview mirror as illustrated in the, in particular under the exterior rearview mirror, or at the bottom of the body or at the bottom of the door. In the non-limiting example illustrated in the, the image Im projected on the ground is a static image which includes a pattern which is a “UOUO” logo. In the non-limiting example of the, the images Im projected on the ground form an animated image. In the non-limiting example, three images Im of a person in three different positions are illustrated which make it possible to produce an animated image of a person walking.

[0093] When the light device 2 is configured to produce a light image, in a non-limiting embodiment, it can be arranged in the interior roof of the vehicle 1 or under the interior central rearview mirror.

[0094] According to one embodiment of the invention, the light device 2 comprises at least one light source 4, for example a light-emitting diode or a set of light-emitting diodes or a laser diode or a set of laser diodes, capable of producing a light beam F. The light beam F is a monochromatic light beam F.

[0095] By light-emitting diode is meant any type of light-emitting diode, whether in non-limiting examples LEDs ("Light Emitting Diode" in English), OLEDs ("Organic LED" in English), AMOLEDs ("Active-Matrix-Organic LED" in English), or FOLEDs ("Flexible OLED" in English). The light from such a light source 4 in the absence of a wavelength converter only comprises rays of a single wavelength, that is to say it only comprises light rays having a specific color.

[0096] According to a non-limiting embodiment, the light source 4 emits a monochromatic light of orange color having a wavelength λ between 590nm and 610nm. It will be noted that a wavelength λ of 590nm corresponds to amber-colored light.

[0097] According to another non-limiting embodiment, the light source emits a monochromatic light of red color having a wavelength λ between 620 nm and 700 nm.

[0098] According to yet another non-limiting embodiment, the light source emits a monochromatic light of cyan color having a wavelength λ between 490 nm and 500 nm.

[0099] According to yet another non-limiting embodiment, the light source 4 emits a monochromatic light of blue color having a wavelength λ between 450 nm and 490 nm.

[0100] According to yet another non-limiting embodiment, the light source 4 emits a monochromatic light of green color having a wavelength λ between 490 nm and 570 nm.

[0101] According to still other non-limiting embodiments, the light source 4 emits a monochromatic light of yellow or magenta color.

[0102] These different colors make it possible to obtain white by mixing blue, red and green, or cyan, magenta and yellow.

[0103] In these various non-limiting embodiments, the lighting device 2 is for example configured to project one or more bands of colored light around the vehicle to inform the driver of his margin of mobility for a maneuver.

[0104] The lighting device 2 is for example configured to project an image Im of the same color as the orientation or maneuvering function. Thus, for the indicator function, the projected image Im will be orange, for the reversing light function, the projected image Im will be white. For the brake light function, the projected image Im will be red.

[0105] In a non-limiting embodiment, the light source 4 may have sufficient power to signal an orientation or maneuvering function or produce static or dynamic light signage, or produce a light image that is visible even in broad daylight.

[0106] The light source 4 may have sufficient power to project an image Im:- on the ground 3 (illustrated on the) at the front of the vehicle 1, or at the rear of the vehicle 1, or on a side of the vehicle 1 which is visible even in broad daylight,- a luminous image on a surface 3 (illustrated on the) located inside the passenger compartment 10 of the vehicle 1 which is visible even in broad daylight.

[0107] The light source 4 may be connected to a printed circuit board 6 shown in Figures 2a, 2b and 16. The printed circuit board 6 may be held by a support 7 (shown in Figures 2a and 2b) possibly comprising a heat sink.

[0108] The light device 2 also comprises at least one optical device 14 juxtaposed with the light source 4 so that the light beam F produced by the light source 4 passes through the optical device 14.

[0109] In addition, the optical device 14 comprises at least one meta-lens 15 configured to modify at least one optical property of the wavefront of the light beam F produced by the light source 4. The light beam F which arrives on the meta-lens 15 is also called the incident light beam F.

[0110] Thus, the transmission rate through an optical device 14 comprising a meta-lens 15 with a monochromatic light beam F is for example greater than 75% and in particular greater than 80%, or even higher. A brighter image Im is thus obtained and / or a less powerful and / or less energy-consuming light source 4 can be used.

[0111] In a non-limiting embodiment, the optical device 14 comprises a thickness of between 1 mm and 2 mm (millimeters). In a non-limiting embodiment, the light device 2 including said at least one light source 4 and the optical device 14 comprises a thickness substantially equal to 1 cm (centimeters). It is a compact light device 2 which makes it possible to gain between 1 and 3 cm compared to the prior art which comprises a thickness of approximately 4 cm. The thickness corresponds to the length in the direction of the optical axis AA' of the light device 2 illustrated in 1a or 2b, or 16.

[0112] Said at least one meta-lens 15 may have an elliptical shape, in particular a circular shape, or a polygonal shape, in particular a quadrilateral shape. According to a non-limiting embodiment, the meta-lens(s) 15 may have a square or rectangular shape. According to a non-limiting embodiment illustrated in the, the meta-lens(s) 15 of the optical device 14 may have a diamond shape. Such shapes, in particular the diamond shape as illustrated in the, may allow a compact matrix arrangement of several meta-lenses 15.

[0113] The meta-lens 15 of the optical device 14 generally comprises a nanostructure 16 (illustrated in the) configured to modify the shape of the wavefront of the light beam F produced by the light source 4 and passing through the optical device 14, and more particularly to modify the amplitude and therefore the intensity and / or the phase and therefore the direction of propagation of the light beam F.

[0114] In a non-limiting embodiment, the meta-lens 15 (substrate 160 and nanopillars 17 included described later) comprises a diameter between 1 mm and 2 mm.

[0115] It should be noted that the fabrication and calculation of the nanostructure 16 of the meta-lens 15 is simpler with a monochromatic light source 4.

[0116] The nanostructure 16 of the meta-lens 15 may comprise an arrangement of nanopillars 17 on its surface. These nanopillars 17 are generally manufactured by nanostructuring, i.e. by electron beam lithography or by nanoimprint lithography in thin layers and arranged in the form of quasi-periodic arrays.

[0117] These nano-sized nanopillars 17 may comprise dielectric materials with a high refractive index, for example a refractive index greater than two.

[0118] More particularly, the nanostructure 16 may comprise a quasi-periodic array of nanopillars 17. By "quasi-periodic" is meant here that the nanopillars within the nanostructure 16 are placed at more or less regular intervals from one another and that they are repeated periodically, and that they are of different sizes (their diameter varies here). We will speak of a periodic array if their sizes are equal. As a non-limiting example, the nanopillars 17 of a nanostructure 16 may be placed at intervals of between 300 nm and 500 nm. In a non-limiting example, they are placed with an interval of 400 nm. In other words, the centers of two neighboring nanopillars 17 are 400 nm apart.

[0119] The nanopillars 17 are for example placed on a transparent substrate 160 (illustrated in the). The material of the transparent substrate 160 is chosen to provide suitable structural support and to allow a majority of the light passing through it to pass through. Such material substrates include for example fused silica, borosilicate glass or even glasses based on rare earth oxides.

[0120] As illustrated in the, in one embodiment, the substrate 160 has a first refractive index n1 and the nanopillars 17 have a second refractive index n2. The first refractive index n1 of the substrate 160 is lower than the second refractive index n2 of the nanopillars 17. These refractive indices n1 and n2 also have an influence on the light beam F which passes through the nanopillars 17 of the nanostructure 16 of the meta-lens 15 and therefore make it possible to modify at least one of the optical properties of the wavefront.

[0121] The optical properties of a meta-lens 15 are mainly defined by the wavelength of the monochromatic light source used, by the refractive index(es) n1 and n2 of the materials used for the substrate 160 and for the nanopillars 17, by the dimensions of the nanopillars 17, by the dimensions of the nanopillars 17 and by their distribution within the nanostructure 16. In other words, the density of material in the nanostructure 16 of the meta-lens 15 defines the effect that the meta-lens 15 has on the light beam F which passes through it.

[0122] The meta-lens 15 is configured to receive a light beam F from a light source 4 and modify its propagation phase φ so that the light beam F is oriented in a given propagation direction P (illustrated in the). In the remainder of the description, the propagation phase φ is otherwise called phase φ.

[0123] In general, the nanopillars 17 may have sections of different sizes from each other. Indeed, the shape and size of the section of a nanopillar 17 of the nanostructure 16 has an impact on the propagation speed of the light beam F which passes through said nanopillar 17, thus modifying at least one of the optical properties of the wavefront of said light beam F which passes through the optical device 14.

[0124] The nanopillars 17 may in particular have a cylindrical shape; in this case, they may comprise a base bs (illustrated in the) of circular shape. The diameter may vary from one nanopillar 17 to another. An example of an arrangement of nanopillars 17 of cylindrical shape with a determined height and different diameters is illustrated in the. The nanopillars 17 thus have a different size (via their diameter). Alternatively, the shape of the base bs could be different from a circular shape, for example a polygonal base, in particular square or rectangular, or even an oblong or elliptical base.

[0125] Furthermore, these nanopillars 17 may have the same height h (illustrated on the) configured to modify the phase of the light beam F produced by the light source 4. For monochromatic light having a given wavelength λ, the ideal height of the nanopillars 17 can be determined to obtain the highest possible transmission rate. The height h of the nanopillars 17 makes it possible to control the phase between 0 and 2π.

[0126] In a non-limiting embodiment, the light source 4 may be configured to emit a light beam with a wavelength λ equal to 590 nm. In this non-limiting example, the refractive index n1 of the material used for the substrate 160 is equal to 1.52 while the refractive index n2 for the nanopillars is equal to 2.36. Still in this non-limiting example, the height h of the nanopillars 17 is 600 nm and the diameter of the nanopillars 17 may be between 50 nm and 150 nm.

[0127] The distribution of the nanopillars 17 within the nanostructure 16 of the meta-lens 15 can be optimized to contribute to a change in the propagation direction P (illustrated in the) of the light beam F. In other words, the distribution of the nanopillars 17 within the nanostructure 16 can be specifically configured to influence the propagation direction P of the light beam F in order to modify the orientation of the light beam at the exit of the meta-lens 15.

[0128] More generally, in a non-limiting embodiment, a meta-lens 15 comprises a quasi-periodic array of nanopillars 17 having different diameters (namely different radii r) so as to influence the speed of propagation of light through the nanopillars 17 so as to modify at least one of the optical properties of the wavefront of the light beam F which passes through the meta-lens 15. Indeed, for two nanopillars 17 having the same height h and different diameters, the nanopillar 17 having a larger diameter will slow down the propagation of the light which passes through it more than the nanopillar with a smaller diameter. This is notably illustrated in the.

[0129] In this way, the nanostructure 16 of the meta-lens 15 can be configured to influence the orientation of the light beam F at the exit of the meta-lens 15 so that the light device 2 emits a light beam F of conical shape in a projection direction P inclined at an angle of between 30° and 90° relative to the propagation direction P of the light beam F produced by the light source 4.

[0130] Furthermore, in the case of a quasi-periodic network, the arrangement of the nanopillars 17, namely the distribution of their radii r, in the nanostructure 16 of the meta-lens 15 can be configured so that the latter has a structure suitable for projecting an image Im with at least one lighting zone z1 with fixed contours onto a surface 3: - in the vicinity (namely around) the vehicle 1 for orientation or maneuvering functions, for producing static or dynamic light signage, or - inside the passenger compartment 10 of the vehicle 1 for producing a light image.

[0131] In a non-limiting embodiment, the projected image Im forms a pattern. In a non-limiting alternative embodiment, the pattern is a geometric pattern. The geometric pattern of the projected image Im has, for example, a simple geometric shape. In the remainder of the description, the pattern is otherwise called a light pattern. It may, for example, be: - an arrow indicating a direction, as illustrated in the, or - a pictogram, - or a set of shapes and / or bands and / or lines as illustrated in Figures 12a, 12b and 13, - or a logo as illustrated in Figure 17, - or a subject as illustrated in Figure 18.

[0132] The nanopillars 17 are described in more detail below.

[0133] The nanopillars 17 are defined by parameters including:- a radius r (illustrated in figures 8 and 9),- a height h (illustrated in figures 8 and 9),- a pitch ps' (illustrated in the) between two nanopillars 17. The pitch ps' represents the repetition frequency of the nanopillars 17,- a material with a refractive index n2 (illustrated in the),- a base bs (illustrated in the).

[0134] It will be noted that the pitch ps' is defined between the two longitudinal axes (illustrated in broken lines on the) of two adjacent nanopillars 17. In a non-limiting embodiment illustrated on the, the nanopillars 17 have a circular base bs.

[0135] In a non-limiting embodiment, the nanopillars 17 are made of Silicon Nitride siN. This material is easy to work with and pollutes less in terms of dust compared to other materials that can be used for the nanopillars 17 such as, in non-limiting examples, Titanium Dioxide (TiO2) or Hafnium Oxide (HfO2).

[0136] In a non-limiting exemplary embodiment, on a substrate 160 with a thickness E=5 millimeters, a 70 nanometer layer of siN can be deposited and the siN layer etched to obtain the nanopillars 17.

[0137] The nanopillars 17 of each meta-lens 15 make it possible to modify the propagation phase φ of a light beam F passing through them. In other words, they add a phase delay. The result is that the light beam F is deflected, giving it a desired propagation direction P.

[0138] All the light beams F thus deflected form a sharp projected image Im substantially at a certain distance (which may be at infinity) on a plane parallel to the substrates 160 of the meta-lenses 15 as illustrated in la or on a plane not parallel to the substrate 160, for example on the ground 3 as illustrated in la. It will be noted that the distance depends on the phase shift introduced by the nanopillars 17. Thus, the light is reoriented towards the areas that are to be illuminated. The other areas are not illuminated and appear as dark. The deflected light beams F are transmitted with a very good light transmission rate. There is thus very little loss of light.

[0139] As illustrated in 12b, the image Im comprises illuminated areas z1 towards which the light has been redirected, and shadow areas z2 (within the illuminated areas z1 in the illustrated non-limiting example and between the illuminated areas z1) towards which the light has not been redirected. The illuminated areas z1 are areas of light concentration.

[0140] Note that the black frame surrounding the illuminated areas z1 is only present to highlight the illuminated areas z1 in Figures 12a and 12b.

[0141] To adjust the propagation direction P, the phase shift within a light beam F is spatially controlled, which amounts to controlling the gradient of the phase change φ of the light beams F. This is done by means of nanopillars 17.

[0142] For this purpose, in a non-limiting embodiment illustrated in the, the nanopillars 17 have different radii r and the same height h. For reasons of readability of the figure, only one height h has been referenced and only one radius r has been referenced.

[0143] It should be noted that the smaller the radius r, the less material a nanopillar 17 contains, which has the consequence of changing the phase φ to a minimum, which amounts to having a small phase delay. On the contrary, when the radius r is larger, the more material a nanopillar 17 contains, which has the consequence of changing the phase φ more significantly, which amounts to having a greater phase delay.

[0144] As illustrated in the, the nanopillars 17 have a radius r that increases from left to right. Each nanopillar 17 will cause a different phase delay φ compared to its neighbor. The larger the radius r, the greater the phase delay φ. The radius r thus acts on the phase φ of the light beam F. Since the radii r are smaller on the left, the phase delays on the left are smaller and the light will be delayed less on the left than on the right.

[0145] As a reminder, light propagates perpendicular to the wavefront. Conventionally, on the same line of the wavefront there is 0 phase delay. As can be seen in the, the input wavefront Fo at the entrance of the meta-lens 15 (also called incident wavefront Fo) is plane and perpendicular to the substrate 160 of the meta-lens 15.

[0146] Each nanopillar 17 introduces a phase delay φ different from its neighbor, because they all have a different diameter, this differential phase delay φ then causes a deformation of the wavefront.

[0147] As can be seen in the figure, the emerging wavefront Fo' is distorted, which therefore causes a deviation of the emerging light beam F after the meta-lens 15.

[0148] Thus, at the exit of a meta-lens 15, the light which always propagates perpendicular to the wavefront, here the emerging wavefront Fo' which is inclined, will be oriented according to a given propagation direction P. Consequently, we obtain an orientation of the light according to a propagation direction P which has changed thanks to the phase shift of the light.

[0149] It will be noted that the emerging wavefront Fo' has been delayed in a progressive and linear manner. Each nanopillar 17 is configured to achieve a phase change φ of the linearly evolving light, namely a linear phase shift. This makes it possible to obtain a planar emerging wavefront Fo'. It will be noted that a phase shift between 0 and 2π is equivalent. It is therefore not necessary to create a linear phase shift all along the input wavefront Fo to obtain a continuous deviation. A phase shift between 0 and 2π can be achieved as many times as necessary. Thus, a linear phase shift between 0 and 10π is equivalent to five linear phase shifts between 0 and 2π.

[0150] It will be noted that the phase φ is modulated between 0 and 2π. It will be noted that with a phase φ = 0, there is no delay. With φ = π, there is a delay of λ / 2. From the point of view of the meta-lens 15, as soon as we have φ = 2π, we return to a radius r of a nanopillar 17 corresponding to 0, and therefore to the same nanopillar 17 to avoid having too large differences between the radii r. Thus, the meta-lens 15 comprises several sets of nanopillars 17 defined so as to obtain a phase shift of the light with a phase modulated between 0 and 2π.

[0151] The height h of the nanopillars 17 allows to control the phase φ between 0 and 2π for a given wavelength λ. With the right height h defined, all phase changes can be made between 0 and 2π.

[0152] As explained previously, the radius r allows to control the phase φ of the light beam Fx.

[0153] The other parameters, namely the height h, the pitch ps', the material of the nanopillars 17, are defined to maximize the transmission rate of light through the nanopillars 17. Maximizing the transmission rate amounts to minimizing the absorption of light by the material of the nanopillar 17. Thus, these other parameters are determined to have a minimal absorption over the range where the radius r is varied to have a phase shift (also called phase difference) between 0 and 2π.

[0154] By calculation, for a nanopillar 17 we fix a given height h and a given pitch ps', and its material which is in a non-limiting example Silicon Nitride siN whose refractive index n2=2.04. In a non-limiting example, h=1.35μm and ps'=0.450μm. Working at a constant height h makes it easier to manufacture the nanopillars 17. With a constant height h, it is necessary to adapt the design of the nanopillars 17 to have a phase shift between 0 and 2π and at the same time have the highest possible light transmission to conserve a maximum of light.

[0155] For the fixed height h and the fixed pitch ps', the curves of light transmission as a function of the radius r, and of phase shift as a function of the radius r, are established. The curves in Figures 10 and 11 illustrate the phase shift and the light transmission for the best compromise for the chosen constant height h and this for a given wavelength λ. It will be noted that this compromise changes if the wavelength λ changes.

[0156] On the, in a non-limiting example, for a height h=1.35µm (micrometers), we can thus observe the phase variation φ in radians (on the ordinate) between 0 and 9 as a function of the radius r (on the abscissa) of the nano-pillars 17 which varies between 0.04 and 0.15 μm, for a given wavelength λ, here for λ=590nm in the non-limiting example illustrated.

[0157] On the, in a non-limiting example, for a height h=1.35µm, we can thus observe a variation in light transmission Tx (on the ordinate) between 0 and 1 as a function of the radius r (on the abscissa) of the nanopillars 17 which varies between 0.04 and 0.15 μm, for the given wavelength λ, here 590nm. At the value 0 for transmission, the light does not pass. At the value 1, for transmission all the light passes.

[0158] With these two curves, we can therefore search and find what is the height h and the radius r of the nanopillars 17 which allows to obtain a phase shift control dynamics while maximizing the light transmission by the nanopillars 17, and remaining manufacturable. We can thus find the values ​​of all the parameters of a nanopillar 17 to obtain the phase shift (or phase difference) and possible transmission values, and in particular a transmission rate close to 1 for a given wavelength λ. It should be noted that if the results are not satisfactory, we can repeat the procedure by fixing another value for the height h.

[0159] The 15 meta-lens has a focal length f.

[0160] It will be noted that the shape of the surface 3 is known in advance. The nanostructure 16 of the meta-lens 15 is thus designed so that, depending on the shape of the surface 3, the focal length f of the meta-lens 15 adapts to the surface 3 and the light beam F which passes through the meta-lens 15 converges at the exit of the meta-lens 15 towards this surface 3 in a convergence zone referenced p in the remainder of the description to obtain a clear image Im. An image focus of the light beam F is obtained which is found at the level of a plane tangent to the surface 3, or even beyond said surface 3.

[0161] Thanks to the adaptive focal length f, we can control the distance at which we must converge. We can thus converge the light beam F exactly on surface 3 and at different distances to adapt to surface 3 if the latter is curved.

[0162] The light beam F of a light source 4 forms a plane wave which illuminates the corresponding meta-lens 15. In a non-limiting embodiment, the light source 4 has a smaller size than the meta-lens 15 which it illuminates so that the light beam F can be well collimated, namely the light cone of the light beam F fits well into said meta-lens 15. In a non-limiting embodiment, the light source 4 has a surface area of ​​0.8mm2.

[0163] As illustrated in particular in figures 2a, 2b, and 16, according to a preferred embodiment, the light device 2 comprises a multitude of light sources 4 and a multitude of meta-lenses 15.

[0164] In a first non-limiting embodiment, a meta-lens 15 is configured to produce an image Im composed of all or part of at least one monochrome pattern.

[0165] Thus, in a non-limiting variant embodiment, to signal an orientation or maneuver function, a meta-lens 15 forms a part of the pattern of the image Im, and several meta-lenses 15 form the different parts of said pattern.

[0166] Thus, in a non-limiting variant embodiment, to produce static luminous signage, a single meta-lens 15 forms the pattern of the image Im for said static luminous signage if the corresponding light source 4 is sufficiently powerful to obtain the desired brightness.

[0167] In a second non-limiting embodiment, a plurality of meta-lenses 15 are configured to produce an image Im composed of one or more monochrome, white or polychrome patterns.

[0168] Thus, in a non-limiting variant embodiment, to produce static luminous signage, several meta-lenses 15 can produce the same pattern of the image Im for said static luminous signage, the patterns overlapping each other.

[0169] Thus, these first and second non-limiting embodiments can be used for the orientation or maneuvering function, or the production of static light signage around the vehicle 1.

[0170] In a third non-limiting embodiment, a plurality of meta-lenses 15 are configured to produce a dynamic monochrome image composed of multiple patterns.

[0171] In a fourth non-limiting embodiment, a plurality of meta-lenses 15 are configured to produce a dynamic polychromatic or white image composed of several patterns.

[0172] Each meta-lens 15 forms a pattern capable of superimposing itself on the other patterns formed by the other meta-lenses 15 and replacing each other to make an animated image.

[0173] Thus, in a non-limiting variant embodiment, to produce dynamic light signage, several meta-lenses 15 can respectively produce several images Im of the animated image for said dynamic light signage. As the light sources 4 corresponding to each meta-lens 15 can be of different colors, it is thus possible to obtain a pattern of different colors, or of white color.

[0174] Thus, these third and fourth non-limiting embodiments can be used for the production of dynamic luminous signage around the vehicle 1.

[0175] As can be seen in Figures 12a and 12b, and 13, the image Im obtained by the optical device 14 with a plurality of meta-lenses 15 comprises illuminated areas z1 and shadow areas z2. To obtain the illuminated areas z1, for a fixed height h and a fixed pitch ps', the radius r of the nanopillars 17 is adjusted to obtain maximum light transmission and the light beams F are reoriented towards the areas to be illuminated as described previously.

[0176] For dynamic light signage, the images Im formed by each meta-lens 15 are created in the same place. Thus, once projected, they end up in the same place on the floor 3. In the context of an animated image, this prevents the successive images Im of the animation from not being in the same position on the floor 3. Otherwise, the desired dynamic effect would not be obtained.

[0177] In a first non-limiting embodiment illustrated in particular in figures 2a, 2b, the light device 2 comprises as many meta-lenses 15 as light sources 4 and each light source 4 is associated with a meta-lens 15 which is specific to it.

[0178] The light sources 4 may be identical to each other or different from each other. In the latter case, each light source 4 may, for example, have a different wavelength λ, and be associated with a meta-lens 15 designed for this type of monochromatic wavelength source, thus emitting a dynamic and unique optical waveform. This provides great flexibility in terms of the color obtained at the output of the light device 2 and the projected image Im.

[0179] In this embodiment, in a non-limiting variant embodiment, the multitude of meta-lenses 15 is arranged in rows and columns within the optical device 14 so as to form a matrix. The multitude of light sources 4 is also arranged in rows and columns so as to form a matrix. The multitude of meta-lenses 15 and the multitude of light sources 4 are arranged relative to each other so that each light beam F produced by one of the light sources 4 passes through the meta-lens 15 with which said light source 4 is associated.

[0180] Thus, a light source 4 of the matrix of light sources 4 is arranged opposite each meta-lens 15 of the matrix of meta-lenses 15. Thus, each meta-lens 15 is crossed by the light beam F produced specifically by the light source 4 with which the meta-lens 15 is associated. Such a matrix arrangement of the light sources 4 and the meta-lenses 15 associated with said light sources 4 may prove to be more compact than in the case of the device known from the state of the art. In other words, such a matrix arrangement of certain components of the light device 2 may contribute to the overall compactness of said light device 2.

[0181] In a first non-limiting variant embodiment illustrated in the, the light device 2 comprises at least three sets ga, gb, gc of light sources 4 juxtaposed next to each other and at least three sets g'a, g'b, g'c of corresponding meta-lenses 15a, 15b, 15c juxtaposed next to each other.

[0182] The three sets ga, gb, gc are arranged next to each other.

[0183] Each set ga, gb, gc comprises at least one light source 4. In the non-limiting example illustrated, each set ga, gb, gc comprises three light sources 4 and each set g'a, g'b, g'c comprises three meta-lenses 15a, 15b, 15c.

[0184] Each set ga, gb, gc of light sources 4a, 4b, 4c is configured to emit monochromatic light of a different color from the other sets ga, gb, gc. In other words, each light source 4 of each set g emits the same monochromatic light as the other two light sources 4 of the same set g.

[0185] In a non-limiting example, the three light sources respectively denoted 3x4a, 3x4b, 3x4c of each set ga, gb, gc are respectively configured to emit a monochromatic light of red color R (λa=620nm in a non-limiting example), of green color V (λb=550nm in a non-limiting example), and of blue color B (λc=450nm in a non-limiting example) so as to obtain a white color.

[0186] Thus, the first set ga comprises three light sources 4a configured to emit a monochromatic light of red color, the second set gb comprises three light sources 4b configured to emit a monochromatic light of green color, and the third set gc comprises three light sources 4c configured to emit a monochromatic light of blue color.

[0187] Thus, the three meta-lenses noted 3x15a, 3x15b, 3x15c respectively associated with the three sets ga, gb, gc of light sources 4 are designed respectively for the three different wavelengths λa, λb, λc, in other words they are tuned to these three wavelengths λa, λb, λc.

[0188] In a second non-limiting embodiment illustrated in the, the light device 2 comprises at least three sets g1, g2, g3 of light sources 4a, 4b, 4c juxtaposed next to each other and at least three sets g'1, g'2, g'3 of corresponding meta-lenses 15a, 15b, 15c juxtaposed next to each other. Each set g1, g2, g3 comprises at least one light source 4. In the non-limiting example illustrated, each set g1, g2, g2 comprises three light sources 4a, 4b, 4c and each set g'1, g'2, g'3 comprises three corresponding meta-lenses 15a, 15b, 15c.

[0189] Each light source 4 of each set g is configured to emit a monochromatic light of a different color from the other light sources 4 of the same set g.

[0190] Thus, the first set g1 comprises three light sources 4a, 4b, 4c configured to emit respectively a monochromatic light of red color R (λa=620nm in a non-limiting example), of green color V (λb=550nm), and of blue color B (λc=450nm in a non-limiting example) so as to obtain a white color. The same applies to the second set g2 and the third set g3.

[0191] Thus, the first set g1' comprises three meta-lenses 15a, 15b, 15c designed for the three different wavelengths λa, λb, λc respectively, in other words they are tuned to these three wavelengths λa, λb, λc. The same applies to the second set g'2 and the third set g'3.

[0192] This second non-limiting variant embodiment makes it possible to have a white color image at a closer distance from the exit of the meta-lenses 15 compared to the first non-limiting variant embodiment.

[0193] In the context of this first non-limiting embodiment illustrated in figures 15a and 15b, to superimpose the images Im produced (in particular in the context of an animated image) by each meta-lens 15a, 15b, 15c as the meta-lenses 15a, 15b, 15c are arranged side by side, it is necessary to have a different linear phase shift for each light beam F of the associated light sources 4,a, 4b, 4c, linear phase shift obtained thanks to the nanopillars 17 as described previously.

[0194] In a second non-limiting embodiment illustrated in the, the light device 2 comprises at least one set g of three light sources 4a, 4b, 4c juxtaposed next to each other and at least one stack s' of three meta-lenses 15a, 15b, 15c arranged opposite said set g, each light source 4a, 4b, 4c being configured to emit light of a different color from the other light sources 4a, 4b, 4c of said at least one set g.

[0195] Thus, in a non-limiting example, three light sources 4a, 4b, 4c are configured to respectively emit a monochromatic light of red color R (λa=620nm in a non-limiting example), of green color V (λb=550nm), and of blue color B (λc=450nm in a non-limiting example) so as to obtain a white color. Thus, we have a set g called RGB.

[0196] The three meta-lenses 15a, 15b, 15c are designed to be tuned respectively with different wavelengths λa, λb, λc. In a non-limiting example, they are tuned respectively to the wavelengths λa (red), λb (green), λc (blue). It will be noted that stacking the meta-lenses 15a, 15b, 15c on top of each other does not greatly increase the volume in thickness of the light device 2, the meta-lenses 15a, 15b, 15c being very thin.

[0197] At the third meta-lens 15c of the s' stack, all the colors are mixed. Thus, at the output of the s' stack, we obtain the color white.

[0198] To make an animated image, the light device 2 comprises at least two sets g of three light sources 4a, 4b, 4c juxtaposed next to each other and two stacks s' of three corresponding meta-lens matrices 15a, 15b, 15c stacked on top of each other.

[0199] It should be noted that the stack arrangement makes it possible to do without a separation wall (which are physical walls) because each meta-lens 15a, 15b, 15c only processes light having the wavelength λ to which it is tuned. Thus, the meta-lens 15a will only process red light, the meta-lens 15b will only process green light, and the meta-lens 15c will only process blue light. The light beams F from each light source 4a, 4b, 4c do not mix with another light beam F. This avoids a stray light phenomenon called "light cross talk".

[0200] Furthermore, since white light is obtained at the third meta-lens 15c of the stack s', there is no colored edge effect on the projected image Im.

[0201] Illustrates the light device 2 with the stack s' configured to project an image Im onto a surface 3 inside the passenger compartment 10 of the vehicle 1. Of course, this stack arrangement s' of the meta-lenses 15 applies for a projection of an image Im onto a surface 3 around the vehicle 1.

[0202] Note that the colors blue, green and red can be replaced by the colors yellow, magenta and cyan to obtain the color white.

[0203] In a non-limiting embodiment, in the case of several light sources 4, the lighting device 2 comprises a collimator per light source 4. This prevents a light beam F from one light source 4 from mixing with another light beam F from another light source 4. This avoids a phenomenon called "light cross talk". Consequently, this avoids having a blurred pattern.

[0204] This also applies to the stacked embodiment to avoid the overflow of one color onto the other before entering the stack of meta-lenses 15.

[0205] In a non-limiting embodiment, the light sources 4 can be switched on or off in the desired order, which has the consequence that the light beams F from said light sources 4 pass through the meta-lenses 15 with which they are associated in the order of activations and deactivations of the light sources 4. Thus, the order does not depend on the arrangement of the meta-lenses 15 within the optical device 14, which can offer more diversity and / or simplicity in the signaling of an orientation or maneuvering function. It is in particular possible to switch on several light sources 4 at the same time and therefore to carry out a more complex and information-rich signaling of an orientation or maneuvering function around the motor vehicle 1.

[0206] Thus, to produce static light signage, in a non-limiting embodiment, the light sources 4 (or set g of light sources 4) corresponding to each meta-lens 15 can be switched on or off simultaneously. Thus, in the non-limiting example of the, to have the image of the “UOUO” logo, the light sources 4 will all be switched on (i.e. activated) at the same time.

[0207] Thus, in a non-limiting embodiment, to produce dynamic light signage, the light sources 4 (or set g of light sources 4) corresponding to each meta-lens 15 can be switched on (activated) or switched off (deactivated) sequentially to form the animated image. Thus, in the non-limiting example of Figure 18, the activation / deactivation sequence of the light sources 4 which illuminate the meta-lenses 15a, 15b and 15c will be as follows: - activation of the light source 4a which illuminates the meta-lens 15a, then - deactivation of the light source 4a which illuminates the meta-lens 15a and simultaneously activation of the light source 4b which illuminates the meta-lens 15b, then - deactivation of the light source 4b which illuminates the meta-lens 15b and simultaneously activation of the light source 4c which illuminates the meta-lens 15c.

[0208] This produces an animated image of a person walking in the non-limiting example illustrated.

[0209] According to a non-limiting embodiment, the optical device 14 further comprises a liquid crystal layer 18.

[0210] In a non-limiting embodiment, the liquid crystal layer 18 is a PDLC layer for “Polymer Disperse Liquid Crystal”.

[0211] The liquid crystal layer 18 extends against the meta-lens 15.

[0212] According to a non-limiting embodiment illustrated in the, the liquid crystal layer 18 and a voltage source 19 adapted to control an electric field passing through the liquid crystal layer 18 can be associated with the meta-lens 15 to form a lens with variable focal length thanks to the phase change of the liquid crystals 18. Such a variable focal length lens therefore allows the meta-lens 15 to modify the convergence zone p of the light beam F on the surface 3 depending on the location of the light device 2 relative to this surface 3 located around the motor vehicle 1 or located inside the passenger compartment 10 of the vehicle 1 so that the projected image Im is clear at the level of this convergence zone p of the light beam F.

[0213] This layer of liquid crystals 18 is arranged on the path of the light beam F produced by the light source 4. It is arranged between the meta-lens 15 and the light source 4.

[0214] The liquid crystal layer 18 comprises a set of liquid crystals whose orientation can be controlled by means of the electric field applied to it.

[0215] The liquid crystal layer 18 is configured to take at least two different states s1, s2 illustrated in the.

[0216] The first state s1 is an inactive state s1 where the liquid crystal layer 18 is inactive in order to preserve the optical properties of the incident light beam F and allow the meta-lens 15 to obtain a first convergence zone p1 of the light beam F on the surface 3. In non-limiting examples, the optical properties are a phase and a polarization.

[0217] Thus, the meta-lens 15 acts on the light beam F which passes through it as in the absence of the liquid crystal layer 18 and its focal length, illustrated f1 on the is adapted as a function of the surface 3 to obtain the convergence zone p1 (as illustrated on the) of the light beam F on the surface 3 and as described previously.

[0218] The second state s2 is an active state where the liquid crystal layer 18 is active in order to modify the optical properties of the incident light beam F and allow the meta-lens 15 to obtain a second convergence zone p2 (as illustrated in the) of the light beam F on the surface 3. The second convergence zone p2 is different from the first convergence zone p1.

[0219] The meta-lens 15 thus acts on this modified light beam F which passes through it by modifying its convergence zone on the surface 3.

[0220] Due to the new optical properties of the light beam F, the meta-lens 15 acts with a modified effective focal length f2 illustrated in the.

[0221] In the non-limiting example illustrated, the focal length f2 is smaller than the focal length f1 so that the light beam F converges towards a shorter convergence zone p2.

[0222] The two states s1, s2 are obtained by modifying the electric field applied to the liquid crystal layer 18.

[0223] In a non-limiting embodiment, the liquid crystal layer 18 is:- in its inactive state s1 when the electric field is applied (i.e. the voltage source 19 is switched on),- in its active state s2 when the electric field is switched off (i.e. the voltage source 19 is switched off).

[0224] It should be noted that a layer of liquid crystals 18 is more compact than a projection optic. It has a thickness of less than 1 mm compared to a projection optic which has a thickness of the order of 2 mm up to 40 mm. It is therefore very thin compared to a projection optic.

[0225] As known to those skilled in the art, the liquid crystal layer 18 requires electrodes (not shown) to create the electric field. In a non-limiting embodiment, the electrodes are transparent to allow light to pass through.

[0226] Thus, the liquid crystal layer 18 makes it possible to obtain a dynamic light device 2 which can adapt to the surface 3 onto which the image Im is projected. Thanks to the electric field which can be modified in real time, the projection of the image Im onto the surface 3 can be adapted in real time unlike a conventional projection optic comprising one or more projection lenses.

[0227] Thus, in a non-limiting example, if we want to project at 5 meters or at 3 meters onto the surface 3 which is the ground 3 for the orientation or maneuvering function, or for static or dynamic luminous signage, we change the value of the electric field unlike a conventional projection optic which in this case must be changed. It is the same if we want to project at approximately 1 m onto a surface 3 which is the dashboard of the vehicle 1.

[0228] In the context of a matrix of meta-lenses 15 as illustrated in FIGS. 2a and 2b, in a non-limiting embodiment, each meta-lens 15 of the matrix previously described is associated with a layer of liquid crystals 18 individually controllable by an electric field. Thus, in a non-limiting embodiment when the light device 2 comprises a matrix with several meta-lenses 15, it comprises several layers of liquid crystals 18, one per meta-lens 15.

[0229] In another non-limiting embodiment, the light device 2 comprises only a single layer of liquid crystals 18 and each meta-lens 15 of the matrix is ​​arranged opposite a different defined zone in the single layer of liquid crystals 18, and each zone is individually controllable by an electric field. These different zones are located opposite each light source 4 corresponding to each meta-lens 15.

[0230] In the context of a stack s' of meta-lenses 15 as illustrated in the, in a non-limiting embodiment, the liquid crystal layer 18 extends along the first meta-lens 15a of the stack s' which faces the set g of light sources 4a, 4b, 4c. It is thus arranged between the set g of light sources 4a, 4b, 4c and the stack s'.

[0231] The advantage of the liquid crystal layer 18 is that it can be adapted to the desired vehicle application according to the manufacturers' requests without modifying the meta-lens(es) 15 used in the lighting device 2. It is thus possible to modify the location where an image Im is projected onto the surface 3 without changing the design of the meta-lens(es) 15. Thus, the lighting device 2 can be used in several different vehicle layouts. In a non-limiting example, for a given manufacturer, if the pattern projected onto the ground 3 must be at 5m instead of 3m onto the ground 3, the liquid crystal layer 18 makes it possible to implement the lighting device 2 in the vehicle concerned by the manufacturer. In another non-limiting example, the liquid crystal layer 18 makes it possible to implement the lighting device 2 in the vehicle concerned by the manufacturer if the latter requests interior lighting on a surface 3 which is the dashboard.

[0232] It is sufficient to adapt the electric field applied to the liquid crystal layer 18 for each manufacturer or type of vehicle requested.

[0233] It will be noted that if the light device 2 comprises a collimator, the liquid crystal layer 18 is arranged after the collimator, therefore between the collimator and the meta-lens 15.

[0234] According to a non-limiting embodiment illustrated in the, the light device 2 further comprises a projection optic 20 comprising one or more projection lenses in order to shape the light beam F and orient it in a desired direction, and to project the light beam F onto a given surface 3 which is not parallel to the substrates 160 of the meta-lenses 15, here on the ground 3 or on a surface 3 inside the passenger compartment 10 of the vehicle 1.

[0235] The interest is to adapt to the desired application according to the manufacturers' requests without modifying the meta-lens(es) 15. It is thus possible to modify the location where an image Im is projected onto the surface 3 without changing the design of the meta-lens(es) 15. Thus, the light device 2 can be used in several different vehicle installations. The projection optics 20 are in fact significantly less expensive than a mold for making a meta-lens 15. It is thus possible to manufacture different projection optics 20 at low cost for different types of vehicles.

[0236] It should be noted that the projection optics 20 can be replaced by a diffractive prism.

[0237] Generally speaking, a projection lens is capable of shaping a light beam in a defined spatial field so that said light beam F is projected in accordance with the functions that the lighting device 2 must fulfill. In other words, a projection lens makes it possible to define the shape of the light beam at the end of the lighting device 2. Thus, a projection lens can make it possible to define the width and / or the height of the light beam F, as well as its length, that is to say up to what distance the light beam F can illuminate, and / or its angle of inclination. Such a projection lens can in particular be configured to orient said light beam F towards the ground so as to project an image Im onto the ground 3 in the vicinity of the motor vehicle 1, as illustrated on the or onto a surface 3 inside the passenger compartment 10 of the motor vehicle 1.

[0238] It will be noted that if the projection of the image Im by the optical device 14 is done at a finite distance, for example 5 meters, and that it is desired to adapt the lighting device 2 to carry out a projection at a greater distance, for example 6 meters, the projection optics 20 must have a negative focal length.

[0239] On the other hand, if the projection of the image Im by the optical device 14 is done at a finite distance, for example 5 meters, and it is desired to adapt the lighting device 2 to carry out a projection at a shorter distance, for example 3 meters, the projection optics 20 must have a positive focal length.

[0240] In a non-limiting embodiment illustrated in the, the light device 2 further comprises: - a housing 21 in which are arranged said at least one light source 4, said optical device 14 with said at least one meta-lens 15, and where appropriate the liquid crystal layer 18 or the projection optics 20, and - a protective cover 22. The cover 22 comprises an opening 220 for the projection of the image Im onto the surface 3.

[0241] It is therefore possible to design a more compact and lighter lighting device 2 which can be easily integrated into a motor vehicle 1. Such a lighting device 2 is capable of simply projecting an image Im with one or more lighting zones z1 with fixed contours for orientation or maneuvering functions, to produce static or dynamic signage, or to produce a luminous image on a surface 3 inside the passenger compartment 10 of the vehicle 1.

[0242] Such a lighting device 2 according to the invention is not susceptible to, or only slightly to, possible shocks and / or vibrations generated by the use of the motor vehicle 1 in which said lighting device 2 is integrated and demonstrates better thermal performance.

[0243] Thus, a light device 2 according to the invention therefore offers a more robust and more reliable alternative than the light devices 2' known from the state of the art.

[0244] The light device 2 according to the invention makes it possible to create an image Im with complex light patterns that can be individually controlled.

[0245] The lighting device 2 according to the invention allows an external observer not to make a difference when the lighting device 2 is on or off, namely neither the style nor the appearance of the vehicle 1 is modified due to the switching on of the lighting device 2. Indeed, the lighting device 2 is small and flat and concealed in the vehicle 1.

[0246] It will be noted that the light device 2 according to the invention is devoid of optical masks, the latter usually allowing the production of one or more light patterns as well.

[0247] Thus, thanks to the lighting device 2 according to the invention, it is no longer necessary to use optical masks to produce the patterns to be projected on the ground, for example. The lighting device 2 uses all or at least almost all of the light from the light sources 4 for projecting an image Im. Furthermore, the lighting device 2 heats up less since it does not block the light.

[0248] The light device 2 according to the invention thus allows the projection onto the ground of an image Im which is synchronized with the orientation or maneuvering function in particular.

[0249] Unlike state-of-the-art DMD systems, the light device 2 according to the invention does not generate a hot spot and has a higher energy efficiency in the sense that it does not need to operate at high temperature.

[0250] Furthermore, the light device 2 according to the invention makes it possible to easily obtain colored light patterns whereas state-of-the-art DMD systems are generally used for black and white light patterns. To obtain colored light patterns, DMD systems become very expensive.

[0251] Unlike state-of-the-art MEMS systems that use a system of mirrors that are likely to move due to vibrations of the motor vehicle, the light device 2 according to the invention is insensitive to such vibrations.

[0252] Unlike state-of-the-art microLEDs where there is a lot of heat loss that leads to wavelength mismatch, the light device 2 according to the invention does not consume much energy and is more efficient.

Claims

Lighting device (2) for a motor vehicle (1), the lighting device being configured to project an image (Im) with at least one lighting zone (z1) with fixed contours onto a projection surface (3) located around the vehicle (1) or onto a surface (3) located inside a passenger compartment of the vehicle (1), the lighting device (2) being characterized in that it comprises: at least one light source (4) configured to produce a monochromatic light beam (F); at least one optical device (14) juxtaposed with the light source (4) so ​​that the light beam (F) passes through the optical device (14), said optical device (14) comprising at least one meta-lens (15) configured to modify at least one property of the wavefront of the light beam (F) so as to orient the light beam (F) in a propagation direction (P). Luminous device (2) according to claim 1, characterized in that the meta-lens (15) of the optical device (14) comprises at least one nanostructure (16) configured to modify the amplitude and / or the phase of the light beam (F) produced by the light source (4) and passing through the optical device so as to influence the orientation of the light beam (F) at the exit of the meta-lens (15). Lighting device (2) according to the preceding claim, characterized in that the nanostructure (16) of the meta-lens (15) is configured to influence the orientation of the light beam (F) at the exit of the meta-lens (15) so that the lighting device (2) emits a light beam (F) of conical shape in a projection direction inclined at an angle of between 30° and 90° relative to the direction of propagation of the light beam (F) produced by the light source (4). Illumination device (2) according to one of the preceding claims, characterized in that said illumination device (2) further comprises a liquid crystal layer (18) arranged between said at least one meta-lens (15) and said at least one light source (4) and configured to take at least two states (s1, s2) including: - an inactive state (s1) where the liquid crystal layer (18) is inactive in order to preserve the optical properties of the incident light beam (F) and allow said at least one meta-lens (15) to obtain a first convergence zone (p1) of the light beam (F) on the projection surface (3), - an active state (s2) where the liquid crystal layer (18) is active in order to modify the optical properties of the incident light beam (F) and allow said at least one meta-lens (15) to obtain a second convergence zone (p2) of the light beam (F) on the projection surface (3). Luminous device (2) according to one of the preceding claims, characterized in that the optical properties of the incident light beam (F) are a phase and a polarization. Luminous device (2) according to one of the preceding claims, characterized in that said luminous device (2) comprises a multitude of light sources (4) and a multitude of meta-lenses (15).

6. A light device (2) according to claim 6, characterized in that said light device (2) comprises at least one set (g) of three light sources (4a, 4b, 4c) juxtaposed next to each other and at least one stack (s') of three meta-lenses (15a, 15b, 15c) arranged opposite said set (g), each light source (4a, 4b, 4c) being configured to emit light of a different color from the other light sources (4a, 4b, 4c) of said at least one set (g), and the three meta-lenses (15a, 15b, 15c) being designed to be tuned to different wavelengths (λa, λb, λc). A light device (2) according to claim 6, characterized in that the multitude of meta-lenses (15) is arranged in rows and columns on the optical device (14) so ​​as to form a matrix, and in that the multitude of light sources (4) is also arranged in rows and columns to form a matrix so that each light beam (F) produced by one of the light sources (4) passes through the meta-lens (15) with which said light source (4) is associated. Luminous device (2) according to claim 6 or claim 8, characterized in that said luminous device (2) comprises at least three sets (g a , g b , g c ) of light sources (4a, 4b, 4c) juxtaposed next to each other and at least three sets (g' a , g' b , g' c ) of corresponding meta-lenses (15a, 15b, 15c) juxtaposed next to each other, each set (g a , gb , g c ) of light sources (4a, 4b, 4c) being configured to emit monochromatic light of a different color from the other sets (g a , g b , g c ). A light device (2) according to claim 6 or claim 8, characterized in that said light device (2) comprises at least three sets (g1, g2, g3) of light sources (4a, 4b, 4c) juxtaposed next to each other and at least three sets (g'1, g'2, g'3) of corresponding meta-lenses (15a, 15b, 15c) juxtaposed next to each other, each light source (4 a , 4 b , 4 c ) of each set (g1, g2, g3) being configured to emit a monochromatic light of a different color from the other light sources (4 a , 4 b , 4 c ) of the same set (g1, g2, g3). Motor vehicle characterized in that it comprises a light device (2) according to any one of the preceding claims.

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