Light device for motor vehicles configured to provide a high beam function and / or a low beam function.

Abstract

Title: Lighting device for a motor vehicle configured to provide a high beam and / or a low beam function. Lighting device (2) for a motor vehicle (1), the lighting device being configured to signal a high beam or a low beam function, the lighting device (2) being characterized in that it comprises: at least one light source (4) configured to produce a light beam (FL) across the entire visible spectrum; at least one optical device (14) juxtaposed to the light source (4) such that the light beam (F) passes through the optical device (14), said optical device (14) comprising at least one metal lens (15) configured to modify at least one property of the wavefront of the light beam (F). Figure for the abstract: Fig. 2

Description

Title of the invention: Lighting device for a motor vehicle configured to provide a high beam function and / or a low beam function.

[0001] The present invention relates to a lighting device for a motor vehicle, the lighting device being configured to provide a high beam function and / or a low beam function, i.e. to project at least one lighting zone in front of a motor vehicle for visibility functions while allowing an improvement in the aerodynamic performance of the motor vehicle. The invention also relates to a motor vehicle equipped with such a lighting device.

[0002] Driving when visibility is reduced, whether due to weather conditions or low light, poses two major challenges for the driver: seeing where they are going and being seen by other road users.

[0003] Motor vehicles therefore comprise lighting devices generally placed on a front face of a vehicle. These lighting devices comprise high beams and dipped beams. High beams are brighter and project a symmetrical beam to illuminate the road over a longer distance. Dipped beams project an asymmetrical beam which illuminates the road over a shorter distance. Dipped beams are intended, for example, for city driving; high beams are intended for dark roads without urban lighting.

[0004] The lighting devices known from the state of the art are generally heavy and bulky, both for high beams and for low beams. Furthermore, the lighting devices known from the state of the art are generally mounted on a front face of the motor vehicle, which contributes to poor aerodynamic performance which leads to greater energy consumption as well as an increase in CO2 emissions. Presentation of the invention

[0005] The objective of the present invention is to provide a lighting device for vehicles which overcomes the above drawbacks and improves the lighting devices known from the prior art. In particular, the lighting device according to the invention aims to be light, compact and capable of performing the functions of a main beam and / or a dipped beam while improving the aerodynamics of the motor vehicle to reduce its energy consumption and its CO2 emission rate.

[0006] Thus, a first object of the invention is a light device which is simple to manufacture and suitable for projecting lighting zones at the front of the motor vehicle with high luminous efficiency.

[0007] A second object of the invention is a more compact and lighter lighting device, easily integrated into a motor vehicle. Summary of the invention

[0008] The invention relates to a lighting device for a motor vehicle, the lighting device being configured to provide a high beam function and / or a low beam function, the lighting device being characterized in that it comprises at least one light source configured to produce a monochromatic light beam and 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.

[0009] According to a particular embodiment, the light device comprises a first light source configured to emit a monochromatic light of red color having a wavelength between 620 nm and 700 nm.

[0010] According to a particular embodiment, the light device comprises a second light source configured to emit a monochromatic light of green color having a wavelength between 490 nm and 570 nm.

[0011] According to a particular embodiment, the light device comprises a third light source configured to emit a monochromatic light of blue color having a wavelength between 450 nm and 490 nm.

[0012] According to a particular embodiment, the light device comprises a set of several meta-lenses juxtaposed with the at least one light source.

[0013] According to a particular embodiment, the meta-lenses are arranged in a stack so that the light beam(s) from the at least one light source pass through the entire stack of meta-lenses.

[0014] According to a particular embodiment, each meta-lens comprises a nanostructure comprising an arrangement of nanopillars on its surface.

[0015] According to a particular embodiment, the nanopillars of the nanostructure specific to each meta-lens have the same height.

[0016] According to a particular embodiment, the height of the nanopillars is specific to each meta-lens.

[0017] According to a particular embodiment, the nanopillars of the same meta-lens have sections of different sizes from each other.

[0018] According to a particular embodiment, the nanopillars have a cylindrical shape and the diameter of the nanopillars is between 100 nm and 320 nm.

[0019] According to a particular embodiment, the at least one meta-lens has an elliptical shape, in particular a circular shape, or a polygonal shape, in particular a square shape or a diamond shape.

[0020] The invention also relates to a motor vehicle equipped with at least one lighting device as presented previously.

[0021] According to a particular embodiment, said at least one light device is arranged on a side face of the motor vehicle. Presentation of figures

[0022] 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:

[0023] [Fig.l] is a schematic view of a motor vehicle equipped with a lighting device configured to provide the functions of a main beam and a dipped beam.

[0024] [Fig.2] is a schematic view of a light device according to a preferred embodiment of the invention.

[0025] [Fig.3] is a schematic perspective view of a detail of a nanostructure of a meta-lens.

[0026] [Fig.4] is another schematic view of a detail of a nanostructure of a meta-lens.

[0027] [Fig. 5] is a schematic view of a motor vehicle equipped with a lighting device according to one embodiment of the invention. Detailed description

[0028] An embodiment of a motor vehicle 1 according to the invention is described below with reference to [Fig.l]. 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. The motor vehicle 1 is equipped with a lighting device 2 configured to provide the functions of a main beam and a dipped beam.

[0029] Examples of the shape of the lighting beam for the dipped beam and for the main beam are illustrated schematically in [Fig.l]. In this [Fig.l], the main beam and the dipped beam are distinguished from each other by the illuminated extent, by the shape of the lighting beam and by the lighting intensity. Thus, the shape of the lighting beam for the dipped beam is wider than the shape of the lighting beam for the main beam, while the main beam makes it possible to illuminate the road in front of the vehicle further than the dipped beam.

[0030] A preferred embodiment of a light device 2 is illustrated in the [Fig.2]. This embodiment aims to provide a solution to the problems identified with the known embodiments of the prior art by proposing an improved lighting device 2. This lighting device 2 is configured to provide the functions of a high beam and a low beam while improving the aerodynamics of the motor vehicle to reduce its energy consumption and its CO2 emissions rate. It can be, for example, arranged at the front of the vehicle 1 or, more advantageously, on the sides of the motor vehicle 1.

[0031] According to a preferred embodiment of the invention, this light device 2 comprises at least one light source and more particularly three distinct light sources 4a, 4b, 4c. The light source(s) 4a, 4b, 4c may be connected to a printed circuit board 6. The printed circuit board 6 may be held by a support 7 possibly comprising a heat sink. These light sources 4a, 4b, 4c are for example monochromatic light-emitting diodes which are capable of producing light beams F having wavelengths distinct from one another and therefore colors different from one another. The light coming from such a light source 4a, 4b, 4c only comprises rays of a single wavelength; that is to say it only comprises light rays having a specific color.

[0032] In this preferred embodiment, the light device comprises a first light source 4a configured to emit a monochromatic light of red color having a wavelength between 620 nm and 700 nm and / or a second light source 4b configured to emit a monochromatic light of green color having a wavelength between 490 nm and 570 nm and / or a third light source 4c configured to emit a monochromatic light of blue color having a wavelength between 450 nm and 490 nm.

[0033] The light device 2 also comprises at least one optical device 14 juxtaposed with the at least one light source 4a, 4b, 4c so that the light beam F produced by at least one of the light sources 4a, 4b, 4c passes through the optical device 14. In addition, the optical device 14 comprises at least one meta-lens 15a, 15b, 15c configured to modify at least one optical property of the wavefront of the light beam F produced by at least one of the light sources 4a, 4b, 4c.

[0034] In the preferred embodiment of the light device 2, the optical device 14 comprises a set of several meta-lenses 15a, 15b, 15c juxtaposed with the at least one light source 4a, 4b, 4c. As illustrated in [Fig. 2], the optical device 14 more precisely comprises a set of three meta-lenses 15a, 15b, 15c which are arranged in a stack so that the beams luminous F of the different light sources 4a, 4b, 4c pass through the entire stack of meta-lenses 15a, 15b, 15c.

[0035] Generally speaking, the meta-lenses 15a, 15b, 15c have the advantage of being flat, extremely thin, very light and compact, which greatly facilitates their integration into lighting devices in general. This also makes it possible to miniaturize the lighting device 2. For example, an individual meta-lens 15a, 15b, 15c can cover an area of ​​between 4mm2 and 100mm2.

[0036] The at least one meta-lens 15a, 15b, 15c may have an elliptical shape, in particular a circular shape, or a polygonal shape, in particular a quadrilateral shape. According to a particular embodiment, the meta-lens(s) 15a, 15b, 15c may have a square or rectangular shape or a diamond shape. Such shapes may allow a compact matrix arrangement of several meta-lenses 15a, 15b, 15c within the optical device 14.

[0037] The meta-lens 15a, 15b, 15c of the optical device 14 generally comprises a nanostructure 16a, 16b, 16c specific to each meta-lens 15a, 15b, 15c and configured to modify the shape of the wavefront of the light beams F produced by the light sources 4a, 4b, 4c 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.

[0038] In the preferred embodiment of the light device 2, each of the meta-lenses 15a, 15b, 15c comprises a nanostructure 16a, 16b, 16c with an arrangement of nanopillars 17 specifically configured to alter the wavefront properties of a light beam from one of the three light sources 4a, 4b, 4c. 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 periodic arrays.

[0039] These nano-sized nanopillars 17 may comprise dielectric materials with a high refractive index, for example a refractive index greater than two. For the sake of clarity, the nanopillars 17 of the nanostructures 16a, 16b, 16c are not shown in [Fig.2].

[0040] The nanostructure 16a, 16b, 16c of each meta-lens 15a, 15b, 15c generally comprises an arrangement of nanopillars 17 on the surface. More particularly, the nanostructure 16a, 16b, 16c may comprise a periodic array of nanopillars 17 on the surface. By “periodic” is meant here that the nanopillars within the nanostructure 16a, 16b, 16c are placed at regular intervals from one another. For example, the nanopillars 17 of a nanostructure 16a, 16b, 16c may be placed at intervals of between 300 nm and 500 nm with a preference for an interval of 400 nm. In other words, the centers of two neighboring nanopillars 17 are distant from 400nm.

[0041] The nanopillars 17 are for example placed on a transparent substrate. The material of the transparent substrate 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.

[0042] The nanopillars 17 and the substrate may have different refractive indices. In one embodiment, the substrate has a first refractive index n1 and the nanopillars 17 have a second refractive index n2. The first refractive index n1 of the substrate is lower than the second refractive index n2 of the nanopillars 17.

[0043] The optical properties of a meta-lens 15a, 15b, 15c are mainly defined by the wavelength of the monochromatic light source 4a, 4b, 4c used, by the refractive index(es) n1 and n2 of the materials used for the substrate and for the nanopillars 17, by the dimensions of the nanopillars 17 and by the distribution of said nanopillars 17 within the nanostructure 16a, 16b, 16c specific to each meta-lens 15a, 15b, 15c. In other words, the density of material in the nanostructure 16a, 16b, 16c of each meta-lens 15a, 15b, 15c defines the effect that the meta-lens 15a, 15b, 15c has on the light beam F which passes through it.

[0044] Generally speaking, 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 16a, 16b, 16c may have an impact on the propagation speed of the light beam F which passes through the meta-lens 15a, 15b, 15c considered, thus modifying the optical properties of the wavefront of said light beam F which passes through the optical device 14.

[0045] The nanopillars 17 may in particular have a cylindrical shape; in this case, they may comprise a circular-shaped base, as illustrated in [Fig. 3]. The diameter may vary from one nanopillar 17 to another. Alternatively, the shape of the base could be different from a circular shape, for example a polygonal base, in particular square or rectangular.

[0046] The distribution of the nanopillars 17 within the nanostructure 16a, 16b, 16c of the meta-lens 15a, 15b, 15c may be optimized to contribute to a change in the direction of propagation of the light beam F passing through the meta-lens 15a, 15b, 15c considered. In other words, the distribution of the nanopillars 17 within the nanostructure 16a, 16b, 16c may be specifically configured to influence the direction of propagation of the light beam F in order to modify the orientation of the light beam at the exit of the meta-lens 15a, 15b, 15c considered.

[0047] Furthermore, for a given meta-lens 15a, 15b, 15c, the nanopillars 17 can have the same height configured to modify the phase of one of the light beams F produced by one of the light sources 4a, 4b, 4c and passing through the meta-lens 15a, 15b, 15c considered. The height of the nanopillars 17 makes it possible to control the phase between 0 and 2ir. For monochromatic light having a given wavelength, the ideal height of the nanopillars 17 can be determined to obtain the highest possible transmission rate. Thus, more than 90% of the light emitted by the light sources 4a, 4b, 4c can be used to illuminate the road in front of the motor vehicle 1.

[0048] In the preferred embodiment, the nanopillars 17 of the same meta-lens 15a, 15b, 15c all have the same height. Furthermore, the height of the nanopillars 17 is specific to each meta-lens 15a, 15b, 15c.

[0049] Thus, in a preferred embodiment for a meta-lens 15a, 15b, 15c considered, the nanostructure 16a, 16b, 16c of the meta-lens 15a, 15b, 15c comprises on its surface an arrangement of nanopillars 17 all having the same specific height, this nanostructure 16a, 16b, 16c of the meta-lens 17 makes it possible to introduce a phase shift of the light beam F with a specific wavelength which passes through the optical device 14, thus modifying the phase of the wavefront of said light beam F. An example of an arrangement of nanopillars 17 of cylindrical shape with a determined height and different diameters is illustrated in [Fig.3].

[0050] By way of example, the light source 4 may be configured to emit a light beam with a wavelength equal to 590 nm. In this particular example, the refractive index n1 of the material used for the substrate is equal to 1.52 while the refractive index n2 for the nanopillars 17 is equal to 2.36. Still in this particular example, the height of the nanopillars 17 is 600 nm and the diameter of the nanopillars 17 may be between 50 nm and 150 nm.

[0051] Each meta-lens 15a, 15b, 15c thus comprises a nanostructure 16a, 16b, 16c which is specific to it with a periodic network of nanopillars 17 having different diameters so as to influence the speed of propagation of the light through the nanopillars 17 so as to modify the properties of the wavefront of the light beam F which passes through the meta-lens 15a, 15b, 15c. Indeed, for two nanopillars 17 having the same height and different diameters, the nanopillar having a larger diameter will slow down the propagation of the light which passes through it more than the nanopillar with a smaller diameter, as illustrated in [Fig.4]. This makes it possible in particular to orient the light beam F at the exit of the light device 2.

[0052] It is thus possible to arrange such a lighting device 2 on one side and / or on a lateral face 3 of the motor vehicle 1 while making it possible to illuminate an area at the front of the motor vehicle 1 to provide a main beam function or a dipped beam function, as illustrated in [Fig. 5]. In the illustrated example in [Fig.5], the light device 2 is more particularly arranged on a side face 3 of the vehicle 1, in an area located between an external rearview mirror and a front wheel.

[0053] It is also possible to use one or more projection lenses in order to shape the light beam F and to orient it in a desired direction. 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.

[0054] It is therefore possible to design a more compact, lighter and more robust lighting device 2 which can be easily integrated into a motor vehicle 1. Such a miniaturized lighting device 2 is capable of simply projecting lighting zones at the front of the vehicle 1 for main beam functions or a dipped beam function.

[0055] 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. Thus, a lighting device 2 according to the invention therefore offers a more robust and more reliable alternative than the lighting devices 2' known from the state of the art.

[0056] Such a miniaturized lighting device 2 can significantly contribute to a reduction in the weight of the motor vehicle 1 in which it is integrated and can also allow a more aerodynamic design of said vehicle to reduce its energy consumption and its CO2 emissions rate.

Claims

Claims

1. Lighting device (2) for a motor vehicle (1), the lighting device being configured to provide a high beam function and / or a low beam function, the lighting device (2) being characterized in that it comprises: • at least one light source (4a, 4b, 4c) configured to produce a monochromatic light beam (F); • at least one optical device (14) juxtaposed with the light source (4a, 4b, 4c) so that the light beam (F) passes through the optical device (14), said optical device (14) comprising at least one meta-lens (15a, 15b, 15c) configured to modify at least one property of the wavefront of the light beam (F).

2. Luminous device (2) according to the preceding claim, characterized in that it comprises a first light source (4a) configured to emit a monochromatic light of red color having a wavelength between 620 nm and 700 nm and / or a second light source (4b) configured to emit a monochromatic light of green color having a wavelength between 490 nm and 570 nm and / or a third light source (4c) configured to emit a monochromatic light of blue color having a wavelength between 450 nm and 490 nm.

3. Luminous device (2) according to the preceding claim, characterized in that it comprises a set of several meta-lenses (15a, 15b, 15c) juxtaposed with the at least one light source (4a, 4b, 4c).

4. Luminous device (2) according to the preceding claim, characterized in that the meta-lenses (15a, 15b, 15c) are arranged in a stack so that the light beam(s) (F) from the at least one light source (4a, 4b, 4c) pass through the entire stack of meta-lenses (15a, 15b, 15c).

5. Luminous device (2) according to one of the preceding claims, characterized in that each meta-lens (15a, 15b, 15c) comprises a nanostructure (16a, 16b, 16c) comprising an arrangement of nanopillars (17) on the surface and in that the nanopillars (17) of the nanostructure (16a, 16b, 16c) specific to each meta-lens (15a, 15b, 15c) have the same height and in that the height of the nanopillars (17) is specific to each meta-lens (15a, 15b, 15c).

6. Luminous device (2) according to one of claims 3 or 4, characterized in that the nanopillars (17) of the same meta-lens (15a, 15b, 15c) have sections of different sizes from each other.

7. Luminous device (2) according to the preceding claim, characterized in that the nanopillars have a cylindrical shape and in that the diameter of the nanopillars (17) is between 100 nm and 320 nm.

8. Luminous device (2) according to one of the preceding claims, characterized in that the at least one meta-lens (15a, 15b, 15c) has an elliptical shape, in particular a circular shape, or a polygonal shape, in particular a square shape or a diamond shape.

9. Motor vehicle characterized in that it comprises at least one light device (2) according to one of the preceding claims.

10. Motor vehicle according to the preceding claim, characterized in that said at least one light device (2) is arranged on a side face (3) of the motor vehicle (1).

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