A light-emitting device for projecting an image onto a surface inside the passenger compartment of a motor vehicle.

Abstract

A lighting device for projecting an image onto a surface located inside the passenger compartment of a motor vehicle. The lighting device for a motor vehicle is configured to project an image onto a surface located inside the passenger compartment of a motor vehicle. The lighting device is characterized in that it comprises: at least one light source configured to produce a monochromatic light beam (F); at least one optical device juxtaposed to the light source such that the light beam (F) produced by the light source passes through the optical device, said optical device comprising a metal lens configured to modify the wavefront of the light beam (F). Figure for the abstract: Fig. 2

Description

Title of the invention: A lighting device for projecting an image onto a surface inside the passenger compartment of a motor vehicle

[0001] The present invention relates to a lighting device for a motor vehicle, the lighting device being configured to project an image onto a surface located inside the passenger compartment of a motor vehicle. The invention also relates to a motor vehicle equipped with such a lighting device.

[0002] There are fixed or portable lighting devices that allow an image to be projected onto a surface located inside the passenger compartment of a motor vehicle, for example, inside the passenger compartment, and in particular on the roof of the passenger compartment. In particular, there are small projection lamps equipped with a light source, such as a light-emitting diode, and a mask with numerous perforations.

[0003] There are also digital dynamic projection systems such as micromirror arrays (called "DMDs" for "digital micromirror devices"), microelectromechanical systems (called "MEMS" for "microelectromechanical systems"), microLEDs, liquid crystal displays, or LCOS video projectors. The light source and the mask are arranged in such a way in the lighting device that part of the light beam produced by the light source passes through the perforated mask, so as to project a multitude of light points onto a surface, thus giving an observer the impression of looking at a starry sky instead of the roof of a car interior.

[0004] A lighting device known in the prior art and employing a mask is generally limited by said mask to the projection of a single-color dot pattern. Using color filters and / or light sources producing distinct colored light beams would make the lighting device larger and bulkier, thus complicating its integration into the passenger compartment of the motor vehicle.

[0005] Moreover, dot patterns are generally static and monotonous. Prior art lighting devices exist that include an actuation means for moving the mask, for example, by rotating it around an axis of rotation, thus giving an observer the impression of looking at a moving starry sky. However, integrating such an actuation means into the lighting device makes it even larger and more cumbersome, which can complicate its integration into the passenger compartment of the motor vehicle.

[0006] Furthermore, known prior art lighting devices are generally limited These devices are not suitable for projecting points or spots and cannot project more complex shapes and / or detailed images because the projection quality is too low. Indeed, when these state-of-the-art lighting devices are used to project images with shapes more complex than a simple set of points onto curved surfaces, these images can appear distorted and blurry, with imprecise outlines and varying light intensity depending on the distance between the light source and the surface onto which the image(s) are projected.

[0007] As for known prior art dynamic projection systems, they are generally heavy and bulky, making their integration into a motor vehicle difficult. These dynamic projection systems are generally not suitable for use inside a motor vehicle because some prior art lighting devices have relatively fragile components that can be damaged, malfunction, or even break if exposed to shocks or if the motor vehicle is used in a rough environment (damaged, dusty, dirty, or other road conditions). The resulting vibrations then prove very problematic because they significantly limit the effectiveness of image projection. Presentation of the invention

[0008] The object of the invention is to provide a lighting device that remedies the above disadvantages and improves upon known lighting devices of the prior art.

[0009] Thus, an object of the invention is a simple lighting device to manufacture and capable of projecting at least one quality image onto a surface located inside a motor vehicle cabin with high luminous efficiency.

[0010] A second object of the invention is a small and lighter lighting device, easily integrated into a motor vehicle.

[0011] A third object of the invention is a lighting device which is not susceptible to shocks and / or vibrations generated by the use of the motor vehicle in which said lighting device is integrated. Summary of the invention

[0012] The invention relates to a lighting device for a motor vehicle, the lighting device being configured to project an image onto a surface located inside the passenger compartment of a motor vehicle, 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 to the light source such that the light beam produced by the light source passes through the optical device, said optical device comprising a metal lens configured to modify at least one property of the beam's wavefront bright.

[0013] According to a particular embodiment, the surface arranged inside the passenger compartment of the motor vehicle is curved.

[0014] According to a particular embodiment, the metal lens of the optical device comprises at least one nanostructure configured to modify the amplitude and / or phase of the light beam produced by the light source and passing through the optical device.

[0015] According to a particular embodiment, the nanostructure comprises a transparent substrate with an arrangement of nanopillars on its surface, wherein the nanopillars all have the same height and wherein the nanopillars have diameters different from each other

[0016] According to a particular embodiment, the diameter of the nanopillars is between 50 nm and 150 nm.

[0017] According to a particular embodiment, the substrate has a first refractive index and the nanopillars have a second refractive index and the first refractive index of the substrate is lower than the second refractive index of the nanopillars.

[0018] According to a particular embodiment, the multitude of meta-lenses is arranged in rows and columns on the optical device so as to form a matrix, and the multitude of light sources is also arranged in rows and columns to form a matrix such that each light beam produced by one of the light sources passes through the meta-lens to which said light source is associated.

[0019] According to a particular embodiment, the optical device further comprises at least one liquid crystal layer extending against at least one metal lens and a voltage source configured to apply an electric field to the liquid crystal layer to form at least one lens with variable focal length through the phase change of the liquid crystals.

[0020] According to a particular embodiment, the optical device includes a projection lens configured to shape the light beam and to direct said light beam towards the ground.

[0021] The invention also relates to a motor vehicle characterized in that it comprises a passenger compartment having at least one surface disposed within said passenger compartment and in that it comprises a lighting device as described above. Figures

[0022] These objects, features and advantages of the present invention will be described in detail in the following description of various particular embodiments made to non-exhaustive title in relation to the attached figures, among which:

[0023] Fig. 1 is a schematic view of a motor vehicle equipped with a lighting device according to the state of the art.

[0024] Fig. 2 is a schematic view of a motor vehicle equipped with a lighting device according to an embodiment of the invention.

[0025] Figure 3 is a schematic view of an optical device according to a preferred embodiment of the invention.

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

[0027] Fig. 5 is another schematic view of a detail of a nanostructure of a meta-lens.

[0028] Fig. 6 is a schematic perspective view of a meta-lens associated with a variable focal length lens. Detailed description

[0029] In [Fig. 1], the vehicle 100' comprises a lighting device 2' according to a prior art embodiment. 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 [Fig. 1], 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 lining of the vehicle body 1.

[0030] In this prior art embodiment, the lighting device 2' comprises at least one light source 4' capable of producing a light beam F' and a mask 5' positioned in the path of the light beam F'. The at least one light source 4' is a monochromatic light source. The light emitted from such a light source 4 consists only of rays of a single color; it emits only light rays having a specific wavelength or a wavelength within a precise range. The mask 5' may be in the form of a cup or a dome positioned above the light source 4', as illustrated in [Fig. 1], and may at least partially encompass the light source 4'.

[0031] 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 include an optical element 7', such as a projection lens, to shape and direct the light beam F' towards the surface 3'.

[0032] In the case where the dome- or cup-shaped mask 5' is movable, the lighting device 2' includes an actuation means 8' in mechanical connection with 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 cabin 10' appears mobile, so that an observer sees light points moving on the surface 3' of the cabin 10' inside the motor vehicle 100'.

[0033] This prior art embodiment has several drawbacks. In particular, such a mask 5' does not allow for the projection of high-quality images when these images have complex shapes. Indeed, if the surface 3' inside the motor vehicle 1' is not flat but curved, this can cause image distortion on said surface 3'. Furthermore, the outlines of any patterns projected by the prior art lighting device 2' onto the surface 3' may be blurry and imprecise, which can impair image quality.

[0034] Furthermore, the actuation means 8' and / or its mechanical connection with the mask 5' may be subject to shocks or vibrations during the use of the motor vehicle 100', which may cause a misalignment of the position of the light device 2'. Such a misalignment may result in a faulty projection of the images in the passenger compartment, which may inconvenience the driver and / or any passengers of the vehicle 100'.

[0035] An embodiment of a motor vehicle 100 according to the invention is described below with reference to [Fig. 2]. Throughout this description, the motor vehicle 100 may be of any type, including a passenger car, a commercial vehicle, a truck, or even a bus. This embodiment aims to provide a solution to the problems identified with the known prior art embodiment by addressing the drawbacks described above and by offering an improved lighting system.

[0036] According to one embodiment of the invention, a lighting device 2 according to the invention comprises at least one light source 4, for example a light-emitting diode or a set of light-emitting diodes, capable of producing a light beam F. The light source 4 can be connected to a printed circuit board 9. The printed circuit board 6 can be held by a support 10 optionally comprising a heat sink.

[0037] At least one light source 4 is configured to produce a monochromatic light beam F. Monochromatic light comprises only rays of a single wavelength, that is to say, it comprises only light rays having a specific color.

[0038] Advantageously, the light source 4 can have sufficient power to project an image onto a surface 3 inside the cabin 10 that is visible even in broad daylight.

[0039] The light device 2 also includes at least one optical device 11 juxtaposed to the light source 4 so that the light beam F produced by the light source 4 passes through the optical device 11. In addition, the optical device 11 includes at least one metal lens 12 configured to modify at least one optical property of the wavefront of the light beam F produced by the light source 4 in order to project an image onto a surface 3 of the passenger compartment, for example onto the roof of the passenger compartment.

[0040] Thus, the transmission rate through an optical device 11 comprising a metal lens 12 with a monochromatic light beam F is, for example, greater than 75% and in particular greater than 80%, or even higher. This results in a brighter image and / or allows the use of a less powerful light source 4 and / or one that consumes less energy.

[0041] At least one meta-lens 12 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 or meta-lenses 12 may have a square or rectangular shape. According to a preferred embodiment illustrated in [Fig. 3], the meta-lens or meta-lenses 12 may have a rhombus shape. Such shapes, in particular the rhombus shape as illustrated in [Fig. 3], may allow for a compact matrix arrangement of several meta-lenses 12.

[0042] The meta-lens 12 of the optical device 11 generally comprises a nanostructure 16 configured to modify the amplitude and / or the phase in order to modify the shape of the wavefront of the light beam F produced by the light source 4 and passing through the optical device 11.

[0043] Here, "nanostructure" refers to a surface with nanometric reliefs such as holes, studs, pillars, or tracks. These reliefs are generally produced by nanostructuring, i.e., by electron beam lithography or nanoimprint lithography, and arranged in the form of periodic arrays.

[0044] The nanostructure 16 of the meta-lens 12 may include an arrangement of nanopillars 17 on its surface. More specifically, the nanostructure 16 may include a quasi-periodic array of nanopillars 17. By "quasi-periodic," it is understood here that the nanopillars within the nanostructure 16 are placed at more or less regular intervals from one another. For example, the nanopillars 17 of a nanostructure 16 may be placed at intervals of 400 nm. In other words, the centers of two neighboring nanopillars 17 are 400 nm apart.

[0045] The optical properties of a metal lens 12 are mainly defined by the wavelength of the monochromatic light source used, by the refractive index(es) of the materials used for the nanopillars 17, by the dimensions of the na nopillars 17 and by their distribution within the nanostructure 16. In other words, the density of matter in the nanostructure 16 of the meta-lens 12 defines the effect that the meta-lens 12 has on the light beam F that passes through it.

[0046] 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 the majority of the light passing through it to pass through. Such substrate materials include, for example, fused silica, borosilicate glass, or rare-earth oxide-based glasses.

[0047] In general, the nanopillars 17 can have cross-sections of different sizes. Indeed, the shape and size of the cross-section of a nanopillar 17 of the nanostructure 16 can have an impact on the propagation speed of the light beam F that passes through said nanopillar 17, thus modifying the optical properties of the wavefront of said light beam F that passes through the optical device 11.

[0048] The nanopillars 17 may, in particular, have a cylindrical shape; in this case, they may comprise a circular base, as illustrated in [Fig. 4]. 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 a square or rectangular one.

[0049] Furthermore, these nanopillars 17 can have the same height configured to modify a phase of the light beam F produced by the light source 4. The light source 4 is configured to emit monochromatic light having a given wavelength, the ideal height of the nanopillars 17 can be determined to obtain the highest possible transmission rate.

[0050] The distribution of the nanopillars 17 within the nanostructure 16 of the meta-lens 12 can be optimized to contribute to a change in the direction of propagation of the light beam. In other words, the distribution of the nanopillars 17 within the nanostructure 16 can 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 12.

[0051] More generally, a meta-lens 12 comprises a quasi-periodic array of nanopillars 17 having different diameters so as to influence the speed of light propagation through the nanopillars 17, thereby modifying the wavefront properties of the light beam F passing through the meta-lens 12. Indeed, for two nanopillars 17 having the same height but different diameters, the nanopillar with a larger diameter will slow down the propagation of light passing through it more than the nanopillar with a smaller diameter, as illustrated in [Fig. 5]. This makes it possible, in particular, to direct the light beam F at the exit of the device luminous 2 so as to project one or more clear images with detailed contours onto the surface 3 inside the passenger compartment 10.

[0052] In one embodiment, the substrate has a first refractive index ni and the nanopillars 17 have a second refractive index n2. The first refractive index ni of the substrate is lower than the second refractive index n2 of the nanopillars 17. These refractive indices ni and n2 also have an influence on the light beam F which passes through the nanopillars 17 of the nanostructure 16 of the metal-lens 12 and therefore make it possible to modify at least one of the properties of the wavefront.

[0053] In one embodiment, the nanostructure 16 of the meta-lens 12 comprises on its surface an arrangement of nanopillars 17 all having the same specific height. This nanostructure 16 of the meta-lens 17 allows for the introduction of a phase shift of the light beam F with a specific wavelength that passes through the optical device 11, thus modifying the phase of the wavefront of said light beam F. The height of the nanopillars 17 allows for the control of the phase between 0 and 2π. An example of a cylindrical arrangement of nanopillars 17 with a determined height and different diameters is illustrated in [Fig. 4].

[0054] By way of example, and according to a preferred embodiment, the light source 4 can be configured to emit a light beam with a wavelength of 590 nm. In this particular example, the refractive index of the material used for the substrate is 1.52, while the refractive index for the nanopillars is 2.36. Also in this particular example, the height of the nanopillars 17 is 600 nm and the diameter of the nanopillars 17 can be between 50 nm and 150 nm.

[0055] Furthermore, the arrangement of the nanopillars 17 in the nanostructure 16 of the meta-lens 12 can be configured so that the latter has a structure suitable for projecting an image comprising a pattern onto the surface 3 inside the passenger compartment of the motor vehicle 1.

[0056] According to a preferred embodiment, the lighting device 2 comprises a multitude of light sources 4 and a multitude of metal lenses 12. In this preferred embodiment, the lighting device 2 therefore comprises as many metal lenses 12 as light sources 4, and each light source 4 is associated with its own metal lens 12. The light sources 4 may be identical or different from one another. In the latter case, each light source 4 may, for example, have a different wavelength and be associated with a metal lens 12 designed for this type of monochromatic wavelength source, thus emitting a unique and dynamic optical waveform.

[0057] In this same embodiment, the multitude of metal lenses 12 is arranged in rows and columns within the optical device 11 so as to form a matrix, as illustrated in [Fig. 2]. In this same embodiment, the multitude of The light sources 4 are also arranged in rows and columns to form a matrix. The multitude of meta-lenses 12 and the multitude of light sources 4 are arranged relative to each other such that each light beam F produced by one of the light sources 4 passes through the meta-lens 12 to which said light source 4 is associated. Thus, each meta-lens 12 is traversed by the light beam F produced specifically by the light source 4 to which the meta-lens 12 is associated.

[0058] Advantageously, the light sources 4 can be switched on or off in the desired order, with the result that the light beams F from said light sources 4 pass through the meta-lenses 12 to which they are associated in the order of the activations and deactivations of the light sources 4. Thus, the order does not depend on the arrangement of the meta-lenses 12 within the optical device 11, which can offer more diversity and / or simplicity in changing the image projected onto the surface 3 inside the passenger compartment of the motor vehicle 1. In particular, it is possible to switch on several light sources 4 at the same time and therefore to project several images simultaneously onto the surface 3 inside the passenger compartment of the motor vehicle 1 in order to create a dynamic animation.

[0059] According to a particular embodiment illustrated in [Fig. 6], a 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 metal lens to form a lens with a variable focal length thanks to the phase change of the liquid crystals 18. This lens with a variable focal length is arranged on the path of the light beam F produced by at least one light source 4. The liquid crystal layer 18 comprises an array of liquid crystals whose orientation can be controlled by means of the electric field applied to it.Such a variable focal length lens 18 thus makes it possible to adapt the focal length fl, f2 according to the location of the light device 2 relative to the surface 3 inside the passenger compartment onto which the light area(s) are projected, especially in the case where said surface 3 is not flat, but curved. Advantageously, each metal lens 12 of the previously described matrix is ​​associated with an individually controllable liquid crystal layer 18. Thus, the light device 2 can produce a plurality of light beams, each light beam having its own focal length.

[0060] It is therefore possible to design a more compact, lighter, and more robust lighting device 2 that can be easily integrated into a motor vehicle 1. Such a lighting device 2 is capable of projecting one or more images onto the surface 3 inside the passenger compartment 10 with greater precision, and whose position and / or orientation can be adjusted. Such a lighting device 2 according to the invention is not susceptible to or The invention minimizes the potential shocks and / or vibrations generated by the use of the motor vehicle 100 in which the lighting device 2 is integrated and demonstrates improved thermal performance. Thus, a lighting device 2 according to the invention offers a more robust and reliable alternative to known prior art lighting devices 2'.

Claims

Claims

1. Lighting device (2) for a motor vehicle (100), the lighting device being configured to project an image onto a surface (3) arranged inside a passenger compartment (10) of a motor vehicle, 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 (11) juxtaposed with the light source (4) so ​​that the light beam (F) produced by the light source (4) passes through the optical device (11), said optical device (11) comprising a meta-lens (12) configured to modify at least one property of the wavefront of the light beam (F).

2. Lighting device (2) according to the preceding claim, characterized in that the surface (3) arranged inside the passenger compartment (10) of the motor vehicle (100) is curved.

3. Luminous device (2) according to one of the preceding claims, characterized in that the meta-lens (12) of the optical device (11) 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 (11).

4. Luminous device (2) according to the preceding claim, characterized in that the nanostructure (16) comprises a transparent substrate with an arrangement of nanopillars (17) on the surface and in that the nanopillars (17) all have the same height and in that the nanopillars (17) have different diameters from each other.

5. Luminous device (2) according to the preceding claim, characterized in that the diameter of the nanopillars (17) is between 50 nm and 150 nm.

6. Luminous device (2) according to one of claims 4 or 5, characterized in that the substrate has a first refractive index (ni) and in that the nanopillars (17) have a second refractive index (n2) and in that the first refractive index (ni) of the substrate is lower than the second refractive index (n2) of the nanopillars (17).

7. Luminous device (2) according to one of the preceding claims, ca- characterized in that it comprises a multitude of light sources (4) and a multitude of meta-lenses (12), and in that each monochromatic light source (4) is associated with a meta-lens (12) which is specific to it.

8. Luminous device (2) according to the preceding claim, characterized in that the multitude of meta-lenses (12) is arranged in rows and columns on the optical device (11) 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 (12) with which said light source (4) is associated.

9. Luminous device (2) according to one of the preceding claims, characterized in that it further comprises at least one layer of liquid crystals (18) extending against the at least one meta-lens (12) and a voltage source (19) configured to apply an electric field to the layer of liquid crystals (18) to form at least one variable focal length lens thanks to the phase change of the liquid crystals (18).

10. Motor vehicle characterized in that it comprises a passenger compartment (10) comprising at least one surface (3) arranged inside said passenger compartment (10) and in that it comprises a lighting device (4) according to one of the preceding claims.

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