WARNING LIGHT SYSTEM FOR MOTOR VEHICLES, AND WARNING LIGHT PROCEDURES

Description

Technical field

[0001] The present invention relates to a light warning system for a motor vehicle, and more particularly to a system comprising detection of another motor vehicle in the vicinity of said motor vehicle. The invention also relates to a light warning method. State of the prior art

[0002] Display systems are known for projecting light information and / or pictograms onto a part of a road scene in order to help, for example, the driver of the motor vehicle to follow a predefined route. However, these display systems require the existence of a sufficient projection space around the vehicle in order to project this light information onto the road scene, for example.

[0003] Display systems are also known that display luminous pictograms on predefined optical surfaces. The dimensions of these luminous surfaces are generally quite small and are constrained in particular by the dimensions of the display systems in which they are embedded, such as for example at the level of rear lights and / or signal lights. These display systems therefore do not allow the projection of complex and / or extensive and / or perfectly visible luminous information in all driving situations, and in particular between several vehicles.

[0004] More specifically, there is a need to increase the capacity for displaying light information between several vehicles in order to improve safety when driving.

[0005] Document US2013 / 327966 A1 describes the use of a stereoscopic display to generate, visible only at a safe distance behind the vehicle, a luminous warning with invariable content to indicate to a following vehicle that it is too close.

[0006] Document EP 2 153 117 B1 describes a light warning system using holograms to display an image whose content varies depending on an inter-vehicle distance.

[0007] Document WO 2013 / 180737 A1 describes a stereoscopic display system.

[0008] The present invention aims to address at least a large part of the above problems and to further lead to other advantages.

[0009] Another object of the invention is to propose a new light warning system for a motor vehicle in order to solve at least one of these problems.

[0010] Another aim of the invention is to increase the display capabilities of luminous information visible from outside the motor vehicle.

[0011] Another object of the present invention is to facilitate the integration of a light warning system on the exterior walls of a motor vehicle. Statement of the invention

[0012] According to a first aspect of the invention, at least one of the aforementioned objectives is achieved with a light warning system for a motor vehicle as defined in claim 1.

[0013] Thus, the warning system in accordance with the first aspect of the invention makes it possible to detect a secondary motor vehicle located close to the main motor vehicle and, depending on the distance from the secondary motor vehicle, to display a stereoscopic image on a display surface of the main motor vehicle in order to inform the secondary motor vehicle, for example about an element of the road scene that it does not yet perceive, or even in relation to a danger linked to the distance separating the secondary motor vehicle from the main motor vehicle.

[0014] By vehicle located nearby, we mean a vehicle located within the detection perimeter of the detection system. This detection perimeter depends in particular on the technology implemented by the detection system. By way of non-limiting example, the detection perimeter extends up to several meters beyond the main motor vehicle, and preferably up to approximately 10 m, preferably still in at least one direction perpendicular to one side of the main motor vehicle and / or radially to said main motor vehicle. The detection system may in particular be an active system, comprising a transmitter and a receiver configured to analyze the deviation of the rays emitted by the detection system, or be a passive system comprising only a receiver.

[0015] Thus, the light warning system according to the first aspect of the invention makes it possible to increase the display capabilities of light information visible from outside the main motor vehicle - and in particular visible to other motor vehicles - in order to improve safety in driving situations.

[0016] The light warning system according to the first aspect of the invention comprises the following features: the light device comprises (i) at least one light source configured to be able to emit at least one light ray, and (ii) at least one light cell, each light cell comprising: a waveguide arranged to transport at least a portion of the at least one light ray emitted by the corresponding light source between a first end located on the light source side and a second end; at least one diffraction grating located at the second end of the waveguide, at least a portion of the diffraction gratings being illuminated by the at least a portion of the light rays transported by the waveguide in order to generate at least one diffraction lobe. Thus, each illuminated diffraction grating generates a diffraction lobe in a particular direction, and all the diffraction gratings of a light cell collectively form a light pixel.Finally, the superposition and / or addition of several light cells thus makes it possible to form stereoscopic images formed by the plurality of light pixels generated by each illuminated light cell;

[0017] The light warning system according to the first aspect of the invention may advantageously comprise at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination: the light device comprises a collimator arranged to optically couple the at least one light source with the waveguide. More particularly, the collimator comprises at least one converging lens in order to make at least a portion of the light rays emitted by the corresponding light source parallel and in order to facilitate their injection into the waveguide; a first diffraction grating has first dimensional characteristics and a second diffraction grating has second dimensional characteristics different from the first dimensional characteristics in order to generate different diffraction lobes when illuminated by the at least one light ray.The dimensional characteristics of the diffraction gratings include in particular the general shape of said diffraction grating, the shape of the "slots" forming said diffraction grating, the different dimensions of the diffraction grating and / or the different dimensions of the "slots" forming said diffraction grating as well as the distance between two directly adjacent "slots". In a known manner, the dimensional patterns forming each diffraction grating represent a "stereoscopic engraving" of an interference image which, when illuminated by a particular light, generates the corresponding diffraction lobe. The light illuminating the diffraction gratings is preferably of the coherent light type. Thus, each diffraction grating is arranged to generate a corresponding diffraction lobe when it is subjected to incident illumination, in a manner known to those skilled in the art.In particular, the different diffraction gratings of a light cell of the light device are arranged to collectively form a light pixel from each diffraction lobe. And the control of all or part of the light cells of the light device makes it possible to generate stereoscopic images from each light pixel produced by each light cell. Control of each light cell, independently of the other light cells of the light device, makes it possible to generate several stereoscopic images. In particular, it is possible to generate animated sequences of stereoscopic images from the light pixels of each light cell.Advantageously, the diffraction gratings comprise geometric patterns making it possible to display a stereoscopic image representative of the distance separating the motor vehicle from the detected obstacle; the first diffraction grating and the second diffraction grating are oriented in different directions, and in particular relative to each other. Orientation is understood to mean a main orientation direction of the dimensional patterns of the corresponding diffraction grating. In other words, it is the direction formed by said notches and / or the direction substantially perpendicular to the direction of repetition of the geometric patterns forming said diffraction grating; . an angle between the orientations of two groups of adjacent diffraction gratings is constant; the display surface comprises a transparent substrate: the waveguide of at least a portion of the light cells of the light device is at least partially fixedly attached to the transparent substrate; the waveguide of at least a portion of the light cells of the light device is fixed by gluing to the transparent substrate, preferably using a transparent glue. Alternatively, the waveguide of at least a portion of the light cells of the light device is fixed by lamination to the transparent substrate; the transparent substrate is formed at least in part by the waveguide of at least one of the light cells of the light device; the at least one light source is of the laser source or light-emitting diode type. Optionally,the light device comprises several light sources each emitting light rays at different wavelengths; the at least one light source is of the laser diode type; the at least one light source comprises a first light source emitting at least one light ray of a first color, for example red, a second light source emitting at least one light ray of a second color, for example green, and a third light source emitting at least one light ray of a third color, for example blue. More generally, the first, second and third light sources can take any color; in other words,each light source can emit light of any visible wavelength. the light device comprises optical multiplexing means arranged to selectively illuminate each diffraction grating of each light cell. the optical multiplexing means makes it possible to direct at least a portion of the light rays generated by the at least one light source towards at least a portion of the diffraction gratings of one or more light cells. alternatively, the optical multiplexing means is arranged to selectively illuminate each group of diffraction gratings, all the diffraction gratings being collectively addressed by the optical multiplexing means. the optical multiplexing means comprises a plurality of controllable deflectors,arranged to be able to take at least a first configuration making it possible to direct a portion of the light rays towards at least a portion of the diffraction gratings of one of the light cells and a second configuration making it possible not to illuminate said at least a portion of the diffraction gratings of said one of the light cells of the light device. By way of non-limiting examples,the optical multiplexing means may comprise at least one reflecting or semi-reflecting mirror and / or at least one lens and / or a plurality of mirrors tilting between two different angular configurations. The optical multiplexing means also comprises a plurality of controllable actuators making it possible to selectively or collectively select the diffraction grating(s) to be illuminated in order to generate the corresponding diffraction lobe and ultimately to generate a particular stereoscopic image; the lighting device comprises an optical shutter located directly above at least part of the light cells,said optical shutter being at least configurable in a first configuration in which at least one of the diffraction lobes formed by one of the diffraction gratings of a light cell and / or the light pixels formed by all the diffraction gratings of a light cell are transmitted through said optical shutter, and a second configuration in which at least one of the diffraction lobes formed by one of the diffraction gratings of a light cell and / or the light pixels formed by all the diffraction gratings of a light cell are absorbed by said optical shutter. Thus, the optical shutter makes it possible to select the light pixels generated by the light cells and which will be "visible" by a user of the light device. In other words,the optical shutter acts as a spatial filter for constructing stereoscopic images by selecting the light pixels transmitted by said optical shutter; the optical shutter comprises a plurality of shutter cells that can be configured selectively or collectively in the first and second configurations; the optical shutter is formed of a liquid crystal display. Alternatively, the optical shutter is formed of an electro-wetting technology display; the display surface is selected from a rear window of the main motor vehicle, and / or a side window of the main motor vehicle, and / or a windshield of the main motor vehicle,and / or a part of the bodywork of the main motor vehicle. The warning system according to the first aspect of the invention thus makes it easier to integrate it on the exterior walls of a motor vehicle and improves its visibility to other motor vehicles; the light warning system comprises a processing unit configured to calculate at least one distance d separating the main motor vehicle from the detected secondary motor vehicle, the control module being configured to control the light device in order to generate at least one stereoscopic image as a function of the calculated distance. The processing unit and / or the control module are, for example, composed of one or more microprocessors and / or a set of arranged controllers. Optionally,the control module and the processing unit may be grouped within one or more of the preceding devices cited as non-limiting examples. the detection system and / or the processing unit and / or the control module are configured to, respectively and in real time, detect the secondary motor vehicle, calculate the distance d and control the lighting device. According to different variants of the warning system according to the first aspect of the invention, the detected secondary motor vehicle and / or the distance which separates the main motor vehicle from the detected secondary motor vehicle may be respectively detected and / or calculated according to predefined sampling frequencies, or as a function of the speed of the main motor vehicle. A sufficiently high sampling frequency makes it possible to detect more quickly the changes in the proximal environment of the main motor vehicle,and in particular to detect more quickly secondary motor vehicles entering the detection perimeter of the detection system. By way of non-limiting example, the sampling frequency of the detection system and / or the sampling frequency of the control module are advantageously greater than 100Hz, and preferably of the order of several kilohertz.

[0018] According to a second aspect of the invention, there is provided a method of luminous warning for a motor vehicle by a luminous warning system according to claim 12, said warning method comprising the following steps detecting the relative position with respect to the main motor vehicle of a secondary motor vehicle by means of a detection system; transmitting by the detection system information, linked to this relative position, to a control module; configuring the light device by the control module in order to display at least one stereoscopic image on a display surface of the light warning system as a function of the information linked to the relative position, the at least one stereoscopic image forming a light pictogram with a warning function.

[0019] Advantageously, the light warning method comprises a step of determining the distance separating the other detected motor vehicle from the main motor vehicle, the display of the at least one stereoscopic image being carried out as a function of the determined distance.

[0020] Preferably, at least one dimension of the stereoscopic image displayed by the light device is proportional to the distance separating the other detected motor vehicle from the main motor vehicle.

[0021] Preferably, the steps of the driving assistance process are carried out in real time.

[0022] According to a third aspect of the invention, there is provided a motor vehicle as defined in claim 15. Such a vehicle is equipped with a light warning system according to the first aspect of the invention or according to any of its improvements and / or comprising means arranged to implement a warning method according to the second aspect of the invention. Description of figures

[0023] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which: there FIGURE 1 illustrates a schematic view of an exemplary embodiment of a light cell arranged to generate a plurality of stereoscopic images in several directions; the FIGURE 2 illustrates a schematic sectional view of an exemplary embodiment of a light device making it possible to select a portion of the stereoscopic images generated by a light cell as illustrated in the FIGURE 1 ; there FIGURE 3 illustrates a first scenario of use of the light device implemented in a light warning system in accordance with the first aspect of the invention; the FIGURES 4A and 4Billustrate a second scenario of use of the light device implemented in a light warning system in accordance with the first aspect of the invention.

[0024] Of course, the features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0025] In particular, all the variants and embodiments described can be combined with each other if there is no technical obstacle to this combination.

[0026] In the figures, elements common to several figures retain the same reference. Detailed description of the invention

[0027] There FIGURE 1 illustrates an exemplary embodiment of a light cell 10 of a light device 100 and forming a light warning system in accordance with the first aspect of the invention, said light system making it possible to generate a plurality of three-dimensional images, visible within a very wide vision zone 120 which can extend up to 180°. The light device 100 is arranged to generate the three-dimensional images simultaneously or sequentially and in different directions and orientations.

[0028] More particularly, the light device 100 comprises a plurality of light cells 10, each light cell 10 implementing a plurality of diffraction gratings oriented in a particular direction. For this purpose, the light device 100 comprises: at least one light source, preferably of the electroluminescent type, arranged to generate at least one light ray 18; a plurality of light cells 10 optically coupled to the light source via at least one collimator, each light cell 10 comprising: o a waveguide 17 taking the form of an at least partly transparent and thin film inside which the at least one incident light ray 19 is propagated; o a first group of diffraction gratings 13a-13c formed on a surface of the waveguide 17 and oriented in a first direction; o a second group of diffraction gratings 14a-14c formed on the surface of the waveguide 17 and oriented in a second direction; o a third group of diffraction gratings 15a-15c formed on the surface of the waveguide 17 and oriented in a third direction;

[0029] Each light cell 10 and / or each diffraction grating 13-15 of a light cell 10 can be addressed selectively or collectively using multiplexing means not visible on the FIGURE 1 . Optionally, the light cells 10 and / or the plurality of diffraction gratings 13-15 can also be collectively or selectively modulated using an external shutter 30 not described in the FIGURE 1 and which will be detailed with reference to the FIGURE 2 The modulation frequency is preferably of the order of a video frequency, that is to say several tens or hundreds of Hertz.

[0030] Each diffraction grating 13-15 is etched on the same surface of the waveguide 17 or fixed integrally on said surface of said waveguide 17, preferably by gluing. Of course, the morphological and / or dimensional characteristics of each diffraction grating 13-15 depend on the three-dimensional image to be formed. In other words, each diffraction grating 13-15 is etched so as to generate a particular image when it is illuminated by at least a portion of the light rays 18 generated by the at least one light source.

[0031] Inside the waveguide 17, the light rays 18 generated by the light source propagate and are called incident light rays 19 when they illuminate at least one of the diffraction gratings.

[0032] The waveguide 17 is arranged to allow the light rays 18 generated by the at least one light source to propagate inside said waveguide 17, by total internal reflection. More particularly, each light source is optically coupled to the waveguide 17 at a collimation zone 11 by means of a collimator for example or by means of a diffraction grating, not shown in the FIGURE 1 , so that at least a portion of the light rays 18 generated by the corresponding light source are introduced into said waveguide 17. The incident light rays 19 propagate inside the collimation zone 11 and in the direction of the plurality of diffraction gratings.

[0033] When the incident light rays 19 arrive at a diffraction grating 13-15, they interact with the corresponding diffraction grating 13-15 and are diffracted, forming diffraction lobes 16 in a direction given by the orientation of the diffraction grating and the direction of illumination of said diffraction grating.

[0034] In the case where the light cell 10 comprises several diffraction gratings 13-15, each illuminated diffraction grating generates a corresponding diffraction lobe in a particular direction conditioned by the orientation of the corresponding diffraction grating. Thus, an observer can receive in his right eye a portion of the rays belonging to a first group of diffraction lobes, and in his left eye rays belonging to a second group of diffraction lobes. The first group of light lobes and the second group of light lobes formed by the diffraction gratings of a light cell collectively form a light pixel visible to the observer. Since the intensities of the diffraction lobes are not the same, it is possible to generate a volumetric stereoscopic effect, making the light pixel of the light cell 10 appear to the observer in a proximal or distal position relative to the waveguide 11.

[0035] For a given orientation of the diffraction grating 13-15, illumination from a first side of the diffraction grating 13-15 produces a first diffraction lobe; and illumination from a second side of the same diffraction grating 13-15 produces a second diffraction lobe. The light pixel corresponding to the diffraction lobes produced by the diffraction gratings 13-15 of the light cell 10 thus appears to be located either in front of or behind the plane of the waveguide 11. It is thus possible to produce a beating effect of the light point by simply alternating the direction from which the diffraction gratings 13-15 are illuminated.

[0036] The generation on the same waveguide 11 of several light cells 10 (not shown on the FIGURE 1 ) allows the creation of several luminous pixels, which collectively form a stereoscopic image for the observer.

[0037] Furthermore, the diffraction gratings 13-15 are designed for a given wavelength (source 18), so as to be able to interact with light rays produced by a light source corresponding to the same wavelength. It is possible to generate on the same waveguide 17 several diffraction gratings corresponding to several different wavelengths, and in particular three diffraction gratings corresponding to three different wavelengths, or three groups of diffraction gratings, each group of diffraction gratings being designed for one of the three given wavelengths. By varying the direction of incidence of the different light sources, it is thus possible to generate three images of different color, simultaneously or alternately.

[0038] It is thus possible to generate three-dimensional color images without using color filters and in a simpler way using a completely transparent light device 100. Subsequently, it is also possible to produce animated sequences of several three-dimensional images in a very simple way.

[0039] As a non-limiting example, the light cell 10 illustrated in the FIGURE 1 comprises a glass substrate acting as a waveguide 17, on the surface of which a layer of silicon nitride is deposited, preferably by electrochemical vapor deposition, and preferably still with a thickness of 100 nm. The diffraction gratings 13-15 are etched on the surface of the layer of silicon nitride by known lithography methods.

[0040] There FIGURE 1illustrates a scanning electron microscopy view of a diffraction grating 20 of such a light cell 10 of a light device. The diffraction grating 20 is manufactured by conventional photolithography techniques and comprises a plurality of slots 21 all parallel and oriented in a main direction, each slot 21 being rectilinear.

[0041] Furthermore, the FIGURE 1schematically illustrates the different diffraction lobes 16 projected by each diffraction grating of a light cell 10 of the light device 100. The light cell 10 is illuminated by a collimated light 18 formed from the light rays which are generated by a light source not shown. Each diffraction grating 13-15 thus illuminated disperses the corresponding light rays 18 by first-order diffraction: each diffraction grating 13-15 forms a diffraction lobe resulting from the interaction of the incident light rays 19 with the shape of the crenellations of said diffraction grating 13-15. Each diffraction grating 13-15 forms a diffraction lobe 16 in a particular direction, the particular directions of all the diffraction gratings 13-15 of the light cell 10 forming the viewing zone 120. All the diffraction lobes 16 of a light cell form a light pixel.

[0042] Thus, a light device comprising a plurality of light cells 10 as illustrated in the FIGURE 1 allows a plurality of three-dimensional static images to be generated, under the effect of illumination of the corresponding diffraction gratings 13-15 by collimated light.

[0043] There FIGURE 2illustrates an exemplary embodiment of a light device 100 comprising a plurality of light cells 10 as described above. The plurality of light cells 10 is illuminated by a light source 40. The light source 40 is optically coupled to the light cells 10 via a collimator 50. The light device 100 also comprises a shutter 30 located directly above the light cells 10. The shutter 30 is arranged to allow all or part of a plane transverse to the propagation of the diffraction lobes 16 and / or the light pixels generated by the light cells 10 to be obscured. More particularly, the shutter 30 comprises a plurality of shutter cells 31-34, each shutter cell 31-34 being able to be controlled selectively or collectively relative to the other shutter cells 31-34.The shutter 30 is controlled by a control module (not shown) in order to configure each shutter cell 31-34 in a passing configuration or in a blocking configuration, each shutter cell 31-34 comprising electrodes electrically connected to said control module in order to be able to electrically polarize them.

[0044] In the passing configuration, the corresponding shutter cell 31-34 has a maximum transmission coefficient, and preferably substantially equal to 1, in order to be transparent or almost transparent and to allow the diffraction lobe(s) formed by a portion of the diffraction gratings 13-15 located below to pass. In the blocking configuration, the corresponding shutter cell 31-34 has a minimum transmission coefficient, and preferably substantially equal to zero, in order to be opaque or almost opaque and to absorb the light rays diffracted by a portion of the diffraction gratings 13-15 located below.

[0045] The on-configuration of a shutter cell 31-34 is obtained for a first value of the electric field applied between its terminals, for example for a high electric potential, corresponding to a non-zero bias voltage. Conversely, the off-configuration of a shutter cell 31-34 is obtained for a second value of the electric field applied between its terminals, for example for a minimal electric potential, corresponding to a zero or minimal bias voltage.

[0046] The shutter cells 31-34 are controlled by the control module so as to be configured in one or other of the preceding configurations to select one or more diffraction lobes and / or light pixels formed by the diffraction gratings 13-15 located below. Thus, a modulation of the shutter cells 31-34 makes it possible to sequentially select a plurality of diffraction lobes 16a-16c and / or a plurality of light pixels formed by the diffraction gratings 13-5 located below, thus making it possible to produce a dynamic visual effect of three-dimensional images 121a-121c.

[0047] As a non-limiting example, the shutter 30 may advantageously take the form of a liquid crystal screen, each shutter cell 31-34 being formed by a liquid crystal cell which can be configured in a passing configuration or a blocking configuration depending on the electric field applied between its terminals. In particular, the shutter 30 may preferably be of the electrowetting screen type.

[0048] THE FIGURES 3 and 4illustrate examples of application of a light warning system 1 according to the first aspect of the invention, and implementing a light device 100 making it possible to generate at least one stereoscopic image 121. The light warning system 1 equips a so-called main motor vehicle 300. In each of the application cases, a control module 310 is provided to configure the light device 100 in order to allow the display of at least one stereoscopic image 121 as a function of a detection of a secondary motor vehicle 400 located near the main motor vehicle 300. To facilitate understanding of the invention, the detection system 200 and the control module 310 associated with the light warning system 1 according to the first aspect of the invention have been represented schematically.

[0049] As described previously, each of the following application uses is implemented by a first step of detecting a secondary motor vehicle 400 located near the main motor vehicle 300 in order to generate proximity information for said secondary motor vehicle 400, and by a second step of displaying at least one stereoscopic image 121 on a display surface 350 of the main motor vehicle 300, as a function of the proximity information.

[0050] The light device 100 applied in each of these cases is arranged to display a plurality of stereoscopic images in at least two different directions on the display surface 350.

[0051] As described above, and in order to generate the plurality of stereoscopic images 121, the light device 100 advantageously comprises (i) at least one light source configured to be able to emit at least one light ray and at least one light cell, each light cell comprising (i) a waveguide arranged to transport at least a portion of the at least one light ray emitted by the corresponding light source between a first end located on the light source side and a second end, and (ii) a plurality of groups of diffraction gratings located at the second end of the waveguide, at least a portion of the diffraction gratings being illuminated by the at least a portion of the light rays transported by the waveguide in order to generate at least one diffraction lobe, all of the diffraction lobes generated by the illuminated diffraction gratings forming the at least one stereoscopic image.

[0052] According to one embodiment of the invention, the proximity detection system 200 of the secondary motor vehicle 400 comprises proximity sensors, for example of the ultrasonic type, or a LIDAR system (acronym for "light detection and ranging", laser remote sensing). The detection system is arranged to detect at least one secondary motor vehicle 400 in a detection zone which advantageously extends over several meters in at least one direction perpendicular to the face of the main motor vehicle 300 on which it is mounted. In the example illustrated in the FIGURE 3, the detection system 200 is advantageously integrated on a rear face of the main motor vehicle 300, and more particularly on the rear bumper of said main motor vehicle 300, in order to be able to detect the secondary motor vehicles 400 located near the rear face of the main motor vehicle 300. Of course, the detection system 200 could be integrated alternatively or additionally on a side face and / or on a front face of the main motor vehicle 300 in order to detect secondary motor vehicles 400 arriving near said main motor vehicle 300 respectively from one of its sides and / or from the front.

[0053] As soon as a secondary motor vehicle 400 enters the detection zone of the detection system 200, or when it crosses a threshold distance located inside the detection zone, then the control module 310 configures the lighting device 100 so that it generates at least one stereoscopic image 121 to warn the secondary motor vehicle 400 of its proximity to the main motor vehicle 300.

[0054] There FIGURE 3 illustrates a first scenario of use of the light device 100 described previously in a light warning system in accordance with the first aspect of the invention and equipping a motor vehicle 300.

[0055] In the illustrated example, the light device 100 is mounted on a rear face of the motor vehicle 300, and more particularly on the rear window 350, at least a portion of said rear window 350 forming the display surface of the light device 100. In particular, the waveguide and the plurality of groups of diffraction gratings are located at the rear window 350 in order to generate the corresponding stereoscopic images 121 at said rear window 350. Of course, the light device 100 makes it possible to generate at least one stereoscopic image 121 as described previously.

[0056] The lighting device 100 is controlled by a control module 310 to generate at least one stereoscopic image when the secondary motor vehicle 400 is detected near the main motor vehicle 300, via the detection system 200. The display surface is thus automatically illuminated regardless of where the secondary motor vehicle 400 is located, as long as it is in the detection zone.

[0057] Depending on the stereoscopic images 121 to be generated, the control module 310 configures the light source(s) of the lighting device 100 and addresses the corresponding diffraction grating(s) in order to generate said corresponding stereoscopic images 121. The light sources are of the laser source type, preferably emitting coherent light, possibly of different colors. The laser sources may be located close to the display surface or remote and optically connected to the diffraction gratings by light guides inside the main motor vehicle 300.

[0058] The light device 100 is then configured to emit a first series of stereoscopic images indicating to the secondary motor vehicle 400 that it is located near the main motor vehicle 300, for example using a pictogram representing an exclamation point inside a triangle. For this purpose, the first series of stereoscopic images 121 is for example displayed in a first direction giving the perception to the secondary motor vehicle 400 that said stereoscopic images 121 are located in a plane located in front of the rear window 350, reinforcing the perception of the light message by the driver of the secondary motor vehicle 400.

[0059] Such an effect is obtained by means of at least one light cell, at least some of whose diffraction gratings are illuminated by light rays emitted by the corresponding light sources and electrically polarized for this purpose. The light rays emitted by the light sources propagate inside the waveguide to reach one or more groups of diffraction gratings and at a first angle of incidence. The interaction between the light rays and the group or groups of diffraction gratings produces several diffraction lobes. Of course, each diffraction grating comprises particular dimensional structures forming one and only one diffraction lobe when illuminated by light rays from the light sources. All of the diffraction lobes generated by the illuminated diffraction gratings collectively form the at least one stereoscopic image.

[0060] It is understood that the implementation of the light device 100 in the vicinity of an appropriate display surface, in particular by placing the waveguide and the face on which the diffraction gratings are formed opposite said display surface, allows the display of stereoscopic image(s) which is particularly effective in terms of information to be communicated to a secondary motor vehicle 400, these stereoscopic images being able to take the form of pictogram(s) and / or written message(s) with a warning function with unequivocal content for the user.

[0061] At regular time intervals, the light device 100 can be controlled by the control module so that it emits a second series of stereoscopic images, making the message transmitted on the display surface dynamic. For example, the second series of stereoscopic images can be identical to the first series of stereoscopic images, but the second series of stereoscopic images is displayed in a second direction, different from the first direction, and giving the user the perception that the second series of stereoscopic images is located further to the right than the first series of images.

[0062] Such an effect is achieved by means of at least one light cell, at least some of whose diffraction gratings are illuminated by light rays emitted by the corresponding light sources and electrically polarized for this purpose. The light rays emitted by the light sources propagate inside the waveguide to reach one or more groups of diffraction gratings and at a second angle of incidence. The diffraction gratings are illuminated from a second direction different from the first illumination direction in order to produce second diffraction lobes, but in a substantially different direction, in order to give the impression that the stereoscopic image has moved.

[0063] Of course, other effects can be achieved on the stereoscopic images generated using such a light warning system, such as for example scrolling, swelling, contraction, pivoting effects, color variations, etc. As described previously, a stereoscopic image 121 generated by a diffraction grating of the lighting device 100 is static when the lighting device 100 is configured by the control module 310 to invariantly illuminate the corresponding diffraction grating at a given angle of incidence.Conversely, a stereoscopic image 121 generated by a diffraction grating of the lighting device 100 is dynamic when the lighting device 100 is configured by the control module 310 to successively illuminate a plurality of diffraction gratings in order to successively generate several static stereoscopic images 121, or when the lighting device 100 is configured by the control module 310 to simultaneously illuminate several diffraction gratings in a plurality of directions and to spatially filter certain of the static stereoscopic images 121 thus generated.Thus, in this second variant of producing dynamic stereoscopic images, the dynamic evolution of a multi-zone shutter located above the display surface makes it possible to configure a transmission coefficient for each zone of said shutter and to transmit or block at least one stereoscopic image generated by the corresponding diffraction grating located below. The dynamic control of the multi-zone shutter, by means of instructions generated by the control module 310, makes it possible to select one or more zones in which the corresponding static stereoscopic image generated by the diffraction grating located directly below is transmitted, and therefore visible.Similarly, dynamic multi-zone shutter control allows one or more zones to be selected in which the corresponding static stereoscopic image generated by the diffraction grating directly below is blocked, and therefore not visible.

[0064] According to an alternative embodiment, the light warning system comprises a processing unit configured to calculate a distance separating the other motor vehicle 400 from the main motor vehicle 300, and possibly to calculate a movement trajectory of said secondary motor vehicle 400. The control module 310 configuring the light device 100 is then able to receive distance and / or position information, and where appropriate trajectory information from the secondary motor vehicle 400, in order to be able to generate dynamic stereoscopic images whose content and / or appearance is scalable and depends on the position and / or distance of the secondary motor vehicle 400 relative to the main motor vehicle 300.

[0065] Advantageously, the detection system and / or the control module 310 and / or the processing unit and / or the lighting device 100 are configured to operate in real time.

[0066] THE FIGURES 4A and 4B illustrate a second scenario of use of the light device 100 implemented in a light warning system 1 in accordance with the first aspect of the invention. More particularly, the FIGURES 4A and 4B illustrate a situation in which a secondary vehicle 400 approaches the main vehicle 300 in a direction F, for example to carry out a parking maneuver.

[0067] Below a threshold distance corresponding to a detection limit of the detection system 200 or to a predetermined value included in the detection zone of said detection system 200, the detection system 200 detects the secondary motor vehicle 400 and transmits to the control module 310 information for detecting the relative position with respect to the main motor vehicle of the detected secondary motor vehicle which allows said control module 310 to configure the lighting device 100 so that it generates at least one stereoscopic image 121.

[0068] In the example illustrated on the FIGURES 4A and 4B , the light device 100 is formed by, or is included in, the rear lights and / or the brake lights of the main motor vehicle 300. The display surface 350 is thus formed by a part of the rear face of the main motor vehicle 300, for example a part of its bodywork.

[0069] In order for the light warning system 1 to operate when the main motor vehicle 300 is not in motion, an electric battery may be provided to power the detection system 200 and, where appropriate, in particular to power the control module 310 and / or the light device 100 in order to be able to emit the stereoscopic images 100.

[0070] Advantageously, the light warning system 1 illustrated in the FIGURES 4A and 4Bthus makes it possible to generate stereoscopic images 121 which depend on the relative position of the secondary motor vehicle 400 with respect to the main motor vehicle 300, and make it possible both to facilitate parking maneuvers of the secondary motor vehicle 400 and to avoid impacts and / or accidents. Thus, the lighting device 100 can be configured to display, possibly in real time, the evolution of the distance separating the secondary motor vehicle 400 from the main motor vehicle 300, thanks to the collaboration between the detection system 200, the processing unit and the control module 310.

[0071] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention as defined by the claims. In particular, the different characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations insofar as they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above can be combined with each other.

Claims

1. Luminous warning system (1) for a primary automotive vehicle, said luminous warning system (1) comprising: - a detection system (200) for computing the relative position with respect to the primary automotive vehicle of at least one secondary automotive vehicle (400) and for transmitting relative-position-related information; - a display surface (350) located on a surface intended to form an outer surface of the primary automotive vehicle (300); - a luminous device (100) for displaying at least one stereoscopic image on the corresponding display surface (350), the stereoscopic image forming at least one luminous pictogram with a warning function; and - a control module (310) for receiving the relative-position-related information transmitted by the detection system (200) and for configuring the luminous device (100), and the stereoscopic image that it displays, depending on this relative-position-related information; - a processing unit configured to compute the distance separating the primary automotive vehicle (300) from the secondary automotive vehicle (400), in which system said luminous device (100) comprises: - at least one light source (40) configured to be able to emit at least one light beam; - at least one luminous cell (10), each luminous cell (10) comprising: ∘ a waveguide (17) arranged to transport at least part of the at least one light beam emitted by the corresponding light source (40) between a first end located on the side of the light source (40) and a second end; ∘ at least one diffraction grating (13-15) located at the second end of the waveguide (17), at least some of the diffraction gratings (13-15) being illuminated by at least some of the light beams transported by the waveguide (17) in order to generate at least one diffraction lobe, characterized in that the control module (310) that configures the luminous device (100) is then capable of receiving distance and / or position information, in order to be able to generate dynamic stereoscopic images, the content and / or appearance of which is variable and depends on the position and / or distance of the secondary automotive vehicle (400) with respect to the primary automotive vehicle (300).

2. Luminous warning system (1) according to Claim 1, characterized in that the luminous device (100) comprises a collimator (50) arranged to optically couple the at least one light source (40) to the waveguide (17).

3. Luminous warning system (1) according to either of Claims 1 and 2, characterized in that a first diffraction grating (13-15) has first dimensional characteristics and a second diffraction grating (13-15) has second dimensional characteristics different from the first dimensional characteristics, so that different diffraction lobes are generated when said diffraction gratings are illuminated by the at least one light beam.

4. Luminous warning system (1) according to the preceding claim, characterized in that the first diffraction grating (13-15) and the second diffraction grating (13-15) are orientated in different directions.

5. Luminous warning system (1) according to any of Claims 1 to 4, characterized in that the at least one light source (40) is of the type of a laser source or a light-emitting diode.

6. Luminous warning system (1) according to the preceding claim, characterized in that the at least one light source (40) comprises: - a first light source (40) emitting at least one light beam of a first colour; - a second light source (40) emitting at least one light beam of a second colour; - a third light source (40) emitting at least one light beam of a third colour.

7. Luminous warning system (1) according to any of the preceding claims, characterized in that the luminous device (100) comprises an optical multiplexing means arranged to selectively illuminate each luminous cell (10).

8. Luminous warning system (1) according to any of the preceding claims, characterized in that the luminous device (100) comprises an optical shutter (30) located plumb with at least some of the luminous cells, said optical shutter (30) being configurable into a first configuration in which the stereoscopic images formed by the one or more corresponding luminous cells are transmitted through said optical shutter (30), and a second configuration in which the stereoscopic images formed by the one or more corresponding luminous cells are absorbed by said optical shutter (30).

9. Luminous warning system (1) according to any of the preceding claims, characterized in that the display surface (350) is chosen from: - a back window of the primary automotive vehicle (300); and / or - a side window of the primary automotive vehicle (300); and / or - a windscreen of the primary automotive vehicle (300); and / or - part of the body of the primary automotive vehicle (300).

10. Luminous warning system (1) according to any of the preceding claims, characterized in that it comprises a processing unit configured to compute at least a distance separating the primary automotive vehicle (300) from the detected secondary automotive vehicle (400), the control module (310) being configured to drive the luminous device (100) in order to generate at least one stereoscopic image depending on the computed distance.

11. Luminous warning system (1) according to the preceding claim, characterized in that the detection system (200) and / or processing unit and / or control module (310) are configured to detect the secondary automotive vehicle (400), to compute the distance (d) and to drive the luminous device (100) in real time, respectively.

12. Luminous warning method for an automotive vehicle, said method being implemented by a luminous warning system (1) according to any of the preceding claims and comprising the following steps: - detection of the relative position with respect to the primary automotive vehicle of a secondary automotive vehicle (400) by means of a detection system (200); - transmission by the detection system of information, related to this relative position, to a control module; - configuration of the luminous device (100) by the control module (310) in order to display at least one stereoscopic image on a display surface (350) of the luminous warning system (1) depending on the relative-position-related information, the at least one stereoscopic image forming a luminous pictogram with a warning function.

13. Warning method according to the preceding claim, characterized in that it comprises a step of determining the distance separating the detected secondary automotive vehicle (400) from the primary automotive vehicle (300), the at least one stereoscopic image being displayed depending on the determined distance.

14. Warning method according to the preceding claim, characterized in that at least one dimension of the stereoscopic image displayed by the luminous device (100) is proportional to the distance separating the detected secondary automotive vehicle (400) from the primary automotive vehicle (300).

15. Automotive vehicle equipped with a luminous warning system (1) according to any of Claims 1 to 11 and / or comprising means arranged to implement a warning method according to any of Claims 12 to 14.