FR3084307A1 - LIGHTING SYSTEM FOR A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a vehicle lighting system (1) comprising a first projection device (10) and a second projection device (20) and configured to project at least one pictogram (7) on the ground. The pictogram is produced only or mainly by a portion of a first pixelated light beam coming from at least one first module (11) of pixelated light projection located in only one of the first projection device (10) and the second projection device (20). The at least one first pixelated light projection module (11) comprises at least one matrix of monolithic electroluminescent elements.

Description

"Motor vehicle lighting system"

The present invention relates in particular to a lighting system for a vehicle, in particular for a motor vehicle.

A preferred application relates to the automobile industry, for the equipment of vehicles, in particular for the production of devices capable of emitting light beams, also called lighting and / or signaling and / or writing functions on the ground. . For example, the invention can allow the production of a segmented type light beam, in particular for signaling and / or participation in lighting functions and / or projection of pictograms at the front of a vehicle. A segmented beam is called a beam, the projection of which forms a mark composed of beam segments, each segment being capable of being lit independently.

Signaling and / or lighting lights for motor vehicles are light devices which include one or more light sources and lens which closes the light. In a simplified manner, the light source emits light rays to form a light beam which is directed towards the ice in order to produce an illuminating surface which transmits light outside the vehicle. These functions must comply with regulations, in particular with regard to light intensity and angles of visibility.

Known lighting modules have so far been provided for emitting light fulfilling a lighting function, for example:

- a dipped beam, directed downwards, also sometimes called a code beam and used in the presence of other vehicles on the road;

- a main beam without cutoff, and characterized by maximum illumination in the center line of the vehicle;

- a light beam for foggy weather, characterized by a flat cut-off and a large illumination width.

These functions can relate to a projection towards the front, or towards the rear of the vehicle.

Recently, technologies have been developed to produce a segmented beam, also called pixelated. The beam, resulting from the different beam segments, is projected by means of an optical projection system generally comprising one or more lenses. The English term "Matrix Beam" is sometimes used for this type of beam. A technology for producing these pixels employs micromirror arrays often called by the acronym DMD (Digital Micro-mirror Device in English): a source, typically a laser, illuminates the matrix, each mirror of which can alternately adopt an active return position of light to the outside, and an inactive position in which light is not emitted (it is for example returned to an internal part of the projector, therefore lost).

One application of segmented beams is the projection of pictograms on the ground. By pictogram is meant here an elementary pattern, for example a shape with a recognizable outline, having an information function for a user, for example the driver of the vehicle, a passenger, or any other person. The pictogram provides a useful indication to the user. The information projected can be complex and can associate several pictograms. Examples are: a direction change arrow, one or more figures indicative of a set speed, a caution sign such as an exclamation mark and / or a triangle points up. It can be solid or be defined by an internal contour and an external contour. Generally, the pictogram is projected towards the front of the vehicle, in a lighting area close to the vehicle, typically in a so-called near field area, namely located in a basic part of a low beam; this part is usually found below the horizon line.

This pictogram information projection mode is currently usually produced by two DMD modules, each placed in a different one of the vehicle's headlights. Since the modules are spaced laterally (that is to say transversely to the optical axis), parallax problems arise. However, they seriously affect the definition accuracy of the pictogram.

The present invention aims to remedy at least in part the drawbacks of current techniques.

The present invention relates, in one aspect, to a vehicle lighting system comprising a first projection device and a second projection device and configured to project at least one pictogram on the ground.

Advantageously, said system is characterized in that the pictogram is produced:

- Either only by a portion of a first pixelated light beam from at least one first pixelated light projection module located in one of only the first projection device and the second projection device; or

- either by a portion of a first pixelated light beam from at least one first pixelated light projection module located in one of the first projection device and the second projection device and by a portion of a second pixelated light beam from at least one second pixelated light projection module located in the other of the first projection device and the second projection device, the light intensity of the portion of the second beam being strictly less than that of the portion of the first beam,

Preferably, the at least one first pixelated light projection module comprises at least one matrix of monolithic electroluminescent elements.

In other words, the pictogram is exclusively or at least mainly (in terms of light intensity relative to its environment) defined by the illumination of at least one first pixelated light projection module present in only one of the two projection devices . The expression "defined" does not mean, however, that the illumination produced at the level of the pictogram comes exclusively from the pixelated light projection module (s), but that it is an illumination differential produced by the said at least one first pixelated light projection module which defines the outline of the pictogram; for example, the illumination from the at least one first module (and possibly from at least one second module) can be superimposed on an illumination corresponding to a basic beam and which is not variable at the level of the outline of the pictogram.

Thus, the production and projection of pictograms on the ground are improved. By using mainly or even exclusively at least one first pixelated light projection module present in only one of the two projection devices, the problems of parallax are reduced or eliminated so that the definition accuracy of the pictogram is increased. At the same time, the use of a matrix of monolithic electroluminescent elements for at least one first module greatly rationalizes the technology of this module and allows, without limitation, a strong modulation of the light intensity produced within this module.

While the current technique suggests that each of the first projection device and second projection device must participate in an equivalent manner in the generation of a pictogram, the present invention operates a light intensity differential between these two devices.

The present invention also relates to a vehicle equipped with at least one system according to the present invention. In particular, two devices can be used that are spaced laterally at the front (or rear) of the vehicle. In particular, the first projection device and the second projection device are potentially arranged on a different side, among a right side and a left side, of a front part or a rear part of the vehicle.

Another aspect of the invention relates to a method for generating light beams.

Preferably, the system is configured to produce a contour zone, surrounding the pictogram, the light intensity of the contour zone being strictly less than that of the pictogram. Thus, the pictogram is more readable and stands out more clearly from the rest of the light projected on the ground.

According to one possibility, the light intensity of the second pixelated light beam is identical in the portion of said second beam and in the contour zone, and the light intensity of the first beam is weaker in the contour zone than in the portion of said first beam of pixelated light. We can therefore play on the piloting of the first module to vary these illuminations.

In one embodiment, the contour zone is surrounded by a context zone, the light intensity of the context zone being strictly greater than that of the contour zone. The contour zone is visible in negative relative to its environment, for example a basic beam of low beam.

Optionally, the light intensity of the portion of the second beam is at least 50% lower than that of the portion of the first beam.

According to a non-limiting possibility, the at least one second pixelated light projection module comprises at least one matrix of monolithic electroluminescent elements.

Optionally, at least one of the first projection device and the second projection device comprises at least one additional pixelated light projection module configured to produce an additional pixelated light beam producing, at least in part, on the ground, a additional pictogram separate from the pictogram.

Optionally, at least one of the first projection device and the second projection device comprises at least two pixelated light projection modules, the corresponding pixelated light beam being from the combination of two elementary beams of pixelated light each from one, different, of the at least two pixelated light projection modules.

Preferably, at least one of the first projection device and the second projection device comprises at least one projection module of another light beam.

According to one possibility, the pictogram is located at least partially in an overlapping zone of the first pixelized beam and the other beam.

Advantageously, the other light beam is a basic beam of low beam.

According to one possibility, the first beam of pixelated light forms at least in part a beam of additional low beam.

Advantageously, the following options can also be implemented alternatively or according to any combination between them:

- The first pixelated light beam and the second pixelated light beam are configured to produce a cut-off area for a low beam; preferably, this area can be moved laterally according to an adaptive beam function known by the acronym ADB (from the English Adaptive Driving Beam).

- The portion corresponding to the pictogram of the first pixelated light beam is produced with a light power of the LEDs greater than that of the other LEDs of the first module and preferably that of LEDs of the second module;

- Each module includes a projection optic;

- At least one of the devices comprises another module, for example a base beam (or near field) of a dipped beam and comprises a shaping optic, preferably between a light source and a projection optic;

- The device generating the first pixelated light beam is located on the driver's side.

In a preferred embodiment, the module is configured to project light beams to the front of a motor vehicle.

Other characteristics and advantages of the present invention will be better understood with the aid of the exemplary description and of the drawings among which:

- Figure 1 shows a front view of a motor vehicle equipped with a system according to the invention;

- Figure 2 shows a light projection diagram at the front of a vehicle;

- Figure 3 shows another possible light projection diagram at the front of a vehicle;

- Figure 4 shows an embodiment of the invention with a pictogram in the form of an arrow.

Unless specifically indicated to the contrary, technical characteristics described in detail for a given embodiment can be combined with technical characteristics described in the context, other embodiments are described by way of example and without limitation.

In the characteristics set out below, the terms relating to verticality, horizontality and transversality (or lateral direction), or their equivalents, are understood in relation to the position in which the lighting module is intended to be mounted in a vehicle. The terms “vertical” and “horizontal” are used in the present description to designate directions, in an orientation perpendicular to the plane of the horizon for the term “vertical” (which corresponds to the height of the modules), and in an orientation parallel to the horizon plane for the term "horizontal". They are to be considered in the operating conditions of the device in a vehicle. The use of these words does not mean that slight variations around the vertical and horizontal directions are excluded from the invention. For example, an inclination relative to these directions of the order of + or - 10 ° is considered here as a minor variation around the two preferred directions.

In the following description, a device is a set of components preferably forming a coherent system, in particular carried by the same chassis, and capable of being mounted on a motor vehicle, at the front or at the rear. It can include one or more modules. The invention may assign a pair of devices to a vehicle, generally to equip a right side and a left side of the front or rear of the vehicle.

FIG. 1 illustrates, by its grille, a motor vehicle 1 equipped with a system of the invention which comprises a first projection device 10 and a second projection device 20. Preferably, the projection devices 10, 20 are arranged in the same way as traditional headlamps, that is to say on opposite sides of the front part 2 (or of the rear part) of the equipped vehicle.

The first device 10, as shown, comprises a first module 11 for projecting pixelated light which it will be seen later that it can be used for the production of pictogram (s), and advantageously for other other functions. In the illustrated embodiment, the device 10 further comprises another module 12, for example of the type of projection of a beam participating in the generation of a basic global beam of a low beam function, advantageously in conjunction with a beam generated by another module 22 equipping the second device. In the embodiment shown in FIG. 1, the configuration of the second device 20 is similar to that of the first device 10, namely that the second device comprises a second module 21 for pixelated light projection, as well as another module 22 previously mentioned. One and / or the other of the first and second devices may include other pixelated light projection modules.

According to the invention, the first pixelized light projection module 11, and advantageously at least one other pixelated light projection module possibly present in the system, are based on a pixelated light source of the monolithic source type. Advantageously, it is associated with a control unit capable of selectively controlling the light intensity of each of the pixels of the pixelized beam, as a function of control instructions received by said control unit.

Advantageously, the optical projection element is arranged so that the pixelated beam has a vertical amplitude of at least 5 ° and a horizontal amplitude of at least 5 °. These horizontal and vertical amplitudes make it possible to ensure that the pixelized beam is projected onto an area of the road large enough to perform writing functions on the road by projecting a pictogram pattern into this pixelized beam, and in particular functions d display of road markings, driving assistance and projection of GPS information, or even adaptive lighting functions requiring pixelation of the lighting beam and in particular non-high beam type lighting functions dazzling or dynamic lighting when cornering. The projection optical element can thus comprise one or a combination of several of the following optical components: lens, reflector, guide, collimator, prism. A shaping optic is not absolutely necessary, as the projection optics can directly image the source.

The term “projection optics” in particular means an optical element, or a combination of optical elements, making it possible to create a real, and possibly anamorphic, image of a part of the projection device, for example the source itself or a mask. , or of an intermediate image of the source, at a distance (finite or infinite) very large compared to the dimensions of the device (of a ratio of the order of at least 30, preferably 100) of the device. This projection optic can consist of one or more reflectors, or alternatively one or more lenses, one or more light guides or a combination of these possibilities.

The term “shaping optics” in particular means an optical element, a combination of optical elements, making it possible to deflect at least part of the rays emitted by the light source of a module. By deflecting, it is meant that the direction of entry of the light ray into the shaping optic is different from the direction of exit of said light ray from the shaping optic. The optical elements concerned can be one or more lenses, one or more reflectors, one or more light guides or a combination of these possibilities. Generally, the shaping optic is a primary optic, placed in front of the secondary optic in the direction of the path of the light to be projected; in which a pixelated source is used to form the images of the pixels which will be projected imaged by the secondary optics.

With regard to the pixelated light source, in a nonlimiting example, it can comprise at least 20 columns and at least 20 rows of elementary emitters, in particular at least 32 rows and columns of elementary emitters. These numbers of columns and minimum rows of elementary emitters, in combination with the above-mentioned vertical and horizontal amplitudes, make it possible to obtain, for each of the elementary light beams, once projected by the optical projection element, a lower angular opening. at 0.5 °, or even less than 0.3 °. In this way, a minimum resolution of the pixelated beam is obtained when it is projected onto the road such that a satisfactory perception of said pattern projected in the pixelized beam is guaranteed by a road user and / or by the driver of the vehicle as well. team.

Advantageously, the elementary emitters and the optical projection element are arranged so that two neighboring pixels, that is to say two adjacent pixels on the same row or on the same column, are contiguous, that is to say that is, their adjacent edges are merged.

Preferably, the electroluminescent source comprises at least one matrix of monolithic electroluminescent elements, also called monolithic matrix. In a monolithic matrix, the electroluminescent elements are grown from a common substrate and are electrically connected so as to be selectively activatable, individually or by subset of electroluminescent elements. The substrate can be predominantly made of semiconductor material. The substrate may include one or more other materials, for example non-semiconductors. Thus each electroluminescent element or group of electroluminescent elements can form a light pixel and can emit light when its or their material is supplied with electricity. The configuration of such a monolithic matrix allows the arrangement of selectively activatable pixels very close to each other, compared to conventional light-emitting diodes intended to be soldered on printed circuit boards. The monolithic matrix, within the meaning of the invention, comprises electroluminescent elements of which a main elongation dimension, namely the height, is substantially perpendicular to a common substrate, this height being at most equal to a millimeter.

Advantageously, the monolithic matrix or matrices capable of emitting light rays can be coupled to a unit for controlling the light emission of the pixelated source. The control unit can thus control (one can also say drive) the generation and / or projection of a pixelated light beam by the light device. The control unit can be integrated into the light device. The control unit can be mounted on one or more of the dies, the assembly thus forming a light module. The control unit may include a central processing unit coupled with a memory on which is stored a computer program which includes instructions allowing the processor to perform steps generating signals authorizing control of the light source. The control unit can thus for example individually control the light emission of each pixel of a matrix. In addition, the luminance obtained by the plurality of electroluminescent elements is at least 60Cd / mm ² , preferably at least 80Cd / mm ² .

The control unit can form an electronic device capable of controlling the electroluminescent elements. The control unit can be an integrated circuit. An integrated circuit, also called an electronic chip, is an electronic component reproducing one or more electronic functions and capable of integrating several types of basic electronic components, for example in a reduced volume (i.e. on a small plate). This makes the circuit easy to implement. The integrated circuit can for example be an ASIC or an ASSP. An ASIC (acronym for "Application-Specific Integrated Circuit") is an integrated circuit developed for at least one specific application (that is to say for a client). An ASIC is therefore a specialized integrated circuit (micro-electronics). In general, it brings together a large number of unique or tailor-made functionalities. An ASSP (acronym for "Application Specific Standard Product") is an integrated electronic circuit (microelectronics) grouping together a large number of functionalities to satisfy a generally standardized application. An ASIC is designed for a more specific (specific) need than an ASSP. The supply of electricity to the monolithic matrices is carried out via the electronic device, itself supplied with electricity using for example using at least one connector connecting it to a source of electricity. The source of electricity can be internal or external to the device according to the invention. The electronic device supplies the light source with electricity. The electronic device is thus able to control the light source.

According to the invention, the light source comprises at least one monolithic matrix, the light emitting elements of which project from a common substrate from which they have grown respectively. Different arrangements of electroluminescent elements can meet this definition of monolithic matrix, since the electroluminescent elements have one of their main dimensions of elongation substantially perpendicular to a common substrate and that the spacing between the pixels, formed by a or several electroluminescent elements grouped together electrically, is low in comparison with the spacings imposed in known arrangements of flat square chips soldered on a printed circuit board.

In particular, the light source according to one aspect of the invention may comprise, as will be described in more detail below, a plurality of electroluminescent elements distinct from each other and which are grown individually from the substrate , being electrically connected to be selectively activatable, if necessary by subassemblies within which rods can be activated simultaneously.

According to an embodiment not shown, the monolithic matrix comprises a plurality of electroluminescent elements, of submillimetric dimensions, which are arranged projecting from a substrate so as to form rods of hexagonal section.

The light-emitting sticks extend parallel to the optical axis of the light module when the light source is in position in the housing.

These light-emitting sticks are grouped, in particular by electrical connections specific to each set, into a plurality of selectively activatable portions. The light-emitting sticks are born on a first face of a substrate. Each electroluminescent rod, here formed by the use of gallium nitride (GaN), extends perpendicularly, or substantially perpendicularly, projecting from the substrate, here made from silicon, other materials such as silicon carbide can be used without departing from the context of the invention. For example, the light-emitting sticks could be made from an alloy of aluminum nitride and gallium nitride (AIGaN), or from an alloy of aluminum phosphide, indium and gallium (AlInGaP). Each electroluminescent rod extends along an elongation axis defining its height, the base of each rod being arranged in a plane of the upper face of the substrate.

The light-emitting sticks of the same monolithic matrix advantageously have the same shape and the same dimensions. They are each delimited by a terminal face and by a circumferential wall which extends along the axis of extension of the rod. When the light-emitting rods are doped and are the subject of a polarization, the light resulting from the semiconductor source is emitted essentially from the circumferential wall, it being understood that light rays can also emerge from the face terminal. As a result, each light-emitting stick acts as a single light-emitting diode and the luminance of this source is improved on the one hand by the density of the light-emitting sticks present and on the other hand by the size of the illuminating surface defined by the circumferential wall. and which therefore extends over the entire periphery, and the entire height, of the stick. The height of a stick can be between 2 and 10 μm, preferably 8 μm; the largest dimension of the end face of a rod is less than 2 μm, preferably less than or equal to 1 μm.

It is understood that, during the formation of the light-emitting rods, the height can be modified from one zone of the light source to another, so as to increase the luminance of the corresponding zone when the average height of the rods constituting it is increased. Thus, a group of light-emitting sticks can have a height, or heights, different from another group of light-emitting sticks, these two groups being constitutive of the same semiconductor light source comprising light-emitting sticks of submillimetric dimensions. The shape of the light-emitting rods can also vary from one monolithic matrix to another, in particular on the section of the rods and on the shape of the end face. The rods have a generally cylindrical shape, and they can in particular have a shape of polygonal section, and more particularly hexagonal. We understand that it is important that light can be emitted through the circumferential wall, whether it has a polygonal or circular shape.

Furthermore, the end face may have a substantially planar shape and perpendicular to the circumferential wall, so that it extends substantially parallel to the upper face of the substrate, or it may have a domed or pointed shape at its center. , so as to multiply the directions of emission of the light leaving this end face.

The light-emitting sticks are arranged in a two-dimensional matrix. This arrangement could be such that the sticks are staggered. Generally, the rods are arranged at regular intervals on the substrate and the separation distance of two immediately adjacent light-emitting rods, in each of the dimensions of the matrix, must be at least equal to 2 μm, preferably between 3 μm and 10 pm, so that the light emitted by the circumferential wall of each rod can exit the matrix of light-emitting rods. Furthermore, it is expected that these separation distances, measured between two axes of extension of adjacent rods, will not be greater than 100 μm.

According to another embodiment, not shown, the monolithic matrix may comprise electroluminescent elements formed by layers of epitaxial electroluminescent elements, in particular a first layer of GaN doped n and a second layer of GaN doped p, on a single substrate, by example of silicon carbide, which is cut for example by grinding and / or ablation to form a plurality of pixels respectively from the same substrate. The result of such a design is a plurality of light-emitting blocks all from a single substrate and electrically connected to be selectively activatable from each other.

In an exemplary embodiment according to this other embodiment, the substrate of the monolithic matrix may have a thickness of between 100 μm and 800 μm, in particular equal to 200 μm; each block can have a length and a width, each being between 50 μm and 500 μm, preferably between 100 μm and 200 μm. In a variant, the length and the width are equal. The height of each block is less than 500 μm, preferably less than 300 μm. Finally, the exit surface of each block can be made via the substrate on the side opposite the epitaxy. The separation distance between two contiguous pixels can be less than 1 μm, in particular less than 500 μm, and it is preferably less than 200 μm. Regarding monolithic chips with electroluminescent blocks:

- The number of pixels can be between 250 and several thousand. A typical value is around a thousand pixels.

- Their overall shape is usually square, and can also be rectangular. The aspect ratio is generally between 1: 1 and 1: 5.

- The size of a unit pixel (square in all known cases, possibly rectangular) is between 100 and 300 μm in the current state of the art.

According to another embodiment not shown, as well with light-emitting sticks extending respectively projecting from the same substrate, as described above, as with light-emitting blocks obtained by cutting of light-emitting layers superimposed on the same substrate, the monolithic matrix may further comprise a layer of a polymeric material in which the electroluminescent elements are at least partially embedded. The layer can thus extend over the entire extent of the substrate or only around a determined group of electroluminescent elements. The polymer material, which can in particular be based on silicone, creates a protective layer which makes it possible to protect the electroluminescent elements without hampering the diffusion of the light rays. In addition, it is possible to integrate in this layer of polymeric material wavelength conversion means, and for example phosphors, capable of absorbing at least part of the rays emitted by one of the elements and of converting at least part of said excitation light absorbed into emission light having a wavelength different from that of the excitation light. It is equally possible to provide that the phosphors are embedded in the mass of the polymer material, or that they are arranged on the surface of the layer of this polymer material.

The light source may further include a coating of reflective material to deflect the light rays towards the exit surfaces of the pixelized source.

The electroluminescent elements of submillimetric dimensions define in a plane, substantially parallel to the substrate, a determined outlet surface. It is understood that the shape of this outlet surface is defined as a function of the number and the arrangement of the light-emitting elements which compose it. It is thus possible to define a substantially rectangular shape of the transmission surface, it being understood that it can vary and take any form without departing from the context of the invention.

The system is preferably equipped with a control member configured to control the activation and deactivation, as well as preferably the power level, of each light source of each module. This control is preferably operated at least on the basis of a parameter linked to the nature of the lighting or signaling function to be produced, or also linked to the definition of the pictogram (s) to be produced.

Thanks to this technology, the beam produced by the first module 11 is advantageously controllable at will so as to selectively illuminate certain parts of the scene at the front (or at the rear) of the vehicle.

The system of the invention makes it possible to generate a pictogram 7, an example of which is given in FIG. 4 in the form of an arrow, indicating a change of direction to the right. In the case shown, the pictogram 7 is surrounded by a contour area 8 itself preferably surrounded by a context area, for example a part of the projection of a base beam 3 (that is to say of field near, projected close to the vehicle) which can, for example, be used to define a low beam function. Preferably, the light intensity of the pictogram 7 is higher than that of the contour zone 8. Likewise, it is advantageous that the light intensity in the contour zone 8 is less than that in the context zone, c that is to say typically the light intensity of the near field beam.

FIG. 2 gives an example of a diagram of projection of light at the front of the vehicle, illustrating a horizon line (horizontal line having the ordinate "0" in the vertical angular movement) and a vertical line passing through the optical axis (vertical line with the abscissa "0" in the horizontal angular movement). The illustrated diagram is divided into 5 ° angular units.

This configuration can correspond to that of a low beam function. A base beam 3 produces a near field projection mainly or totally below the horizon line. Preferably, the base beam 3 includes the superposition of a beam from a module 12 present in the first device and a beam from a module 22 present in the second device. In addition, the first module 11 (and / or another pixelated light projection module, for example a module 21 of the second device 20) can also be used to generate the base beam 3, advantageously in addition to another module , in particular the module 12 illustrated in FIG. 1.

For example, the module 12 and / or the module 22 can comprise a light source (for example with light-emitting diodes, of the LED or OLED type) as well as a shaping optic (for example to widen the outgoing beam).

In addition to the base beam 3, a cut-off zone 4 is defined at least in part, but preferably for the most part, or even completely, above the horizon line. The cutting zone can have a profile adapted to the desired function, in particular with an angled shape if necessary (a shape called "kink" not shown). In the embodiment of FIG. 2, the cut-off zone 4 can have a variable lateral position so as to change the cut-off zone 4 according to considerations of running of the vehicle (for example of a turn operated by the vehicle) or outside (for example by the presence of a pedestrian or a crossover car). In particular, the present invention makes it possible in this context to perform an adaptive low beam function, known under the term Adaptive Driving Beam.

FIG. 2 finally presents a zone 5 for pictogram writing, schematizing a potential place, purely indicative, of projection of at least one pictogram according to the invention. In the illustrated case, the zone 5 is located in the projection zone of the beam 3. The pictogram is therefore produced in superimposition of intensity (that is to say in positive) with respect to the beam 3.

In one embodiment, the first module 11 serving, at least in part, for the definition of a pictogram 7, also serves, at least in part, for the generation of the cut-off zone 4.

In the first embodiment, only the first pixelated light projection module 11 is used, or at least only pixelated light projection modules arranged exclusively in the first device 10, to generate a pictogram 7. This does not exclude not the presence of at least one second pixelated light projection module 21 in the second device 20.

In this configuration, the technical problems associated with the parallax between the first and second devices are eliminated. In particular, it is possible, in the portion of the first beam coming from the first module 11 corresponding to the pictogram 7, to control the light source so that the power is maximum, or at least greater than a nominal base power of the monolithic source . In this context, one or more pixelated light projection modules 21 possibly present in the second device 20 are inactive in the portion corresponding to the pictogram 7. In the contour area 8, the light intensity is advantageously lower than that of the pictogram 7. This can be produced only by the at least one first module present in the first device 10, with a power level lower than that used for the pictogram 7. According to another option, in this contour zone 8, at least one second module 21 present in the second device 20 also produces an illumination, but it is arranged so that the sum of the light intensities is, in this zone, less than the light intensity in the zone of pictogram 7. Also, the zone contour 8 can be illuminated only by at least one second module 21 located in the second device 20, with a level of intensity reduced light relative to that used for the at least one first module 11 of the first device 10 in the pictogram area 7. Optionally, both the at least first module 11 and the at least one second module 21 are inactive in the area contour 8 and the illumination at this location is only produced by the base beam 3.

The context zone situated around the contour zone 8 and here forming part of the basic beam 3 can be distinguished from the contour zone 8 by a light intensity greater than that of this latter zone. For example, the contour zone 8 can be illuminated at the same time by at least one first module 11 and at least one second module 21, at a power level each reduced relative to the maximum possible power.

It will be noted that a simple solution ensuring high contour precision and a clear readability of the pictogram 7 is:

- to exclusively use the at least one first module 11 for the definition of the pictogram 7 (with a predetermined power level producing a high light intensity),

- to exclusively use the at least one second module 21 for defining the contour area 8 (with a predetermined power level producing a lower light intensity than that of pictogram 7),

- using the at least one first module 11 and the at least one second module 21 for the definition of a context zone around the contour zone 8 (with a predetermined power level, for example corresponding to that used for the second module in the contour zone 8, but by superimposing the light intensities coming from each of the first module and second module.

In another embodiment, the pictogram 7 is defined with a superposition of light coming from at least a first module 11 and from at least a second module 21. In other words, the first device 10 and the second device 20 overlap, in this case, their illuminations at the pictogram 7. However, in this option, the light intensity generated by the at least one first module 11 is greater than that generated by the at least one second module 21 in the portion corresponding to pictogram 7, so that the latter is mainly defined by the illumination of the first module or modules 11 present in the first device 10. For example, the light intensity coming from the second module or modules 21 in the portion of pictogram 7 is reduced by at least 20%, preferably by at least 50%, or even by at least 80% compared to the light intensity from the first module (s) 11 in the portion of the pictogram e 7.

Optionally, the light intensity from the second module (s) 21 is identical in the contour zone 8 and in the portion corresponding to the pictogram 7. Thus, the intensity differentiation in these two areas is effected by variation of the intensity light produced by the at least one first module 11. In particular, the corresponding parts of the monolithic source of the at least one first module 11 can be switched off in the contour zone 8.

This second embodiment may possibly allow an increase in light intensity in the pictogram area 7 relative to the first embodiment for which only the first module (s) 11 are active to define the pictogram 7. Possibly, this may cause slight degradation of the accuracy of the outline of pictogram 7, due to the effects of the parallax between the first and second devices. However, good modulation of the light intensities makes it possible to find a very satisfactory compromise.

FIG. 3 presents another projection configuration compared to that of FIG. 2. This time, an additional pictogram writing area 6 is presented. It means that it is possible to project different pictograms in separate areas. The indications given above for the generation of the pictogram 7 are possibly applicable for the generation of another pictogram in the zone 6. It will be noted that it is possible to use only, or at least for the most part, at least one first module 11 present in the first device 10 to generate the pictogram 7, to use only, or at least for the most part, at least one second module 21 present in the second device 20 to generate another pictogram in the area 6. It is not excluded that zones 5 and 6 overlap at least partially.

In one embodiment, at least one of the devices 10, 20 comprises a plurality of pixelated light projection modules allowing the generation of different pictograms separately.

Possibly, the invention can participate in producing a driving beam. The function of the basic driving beam is to illuminate the scene in front of the vehicle over a wide area, but also over a considerable distance, typically around two hundred meters. This light beam, by its lighting function, is mainly located above the horizon line. It may have a slightly ascending optical axis of illumination, for example. In particular, one of the pixelized light projection modules described above, or any other module, in particular of pixelated light projection, can be used to generate a lighting function of the "road complement" type which forms a portion of a light. of complementary road to that produced by a base beam (of near field), the road complement seeking in whole, or at least mainly, to illuminate above the horizon line while the near field beam (which can present the specifics of a low beam) seeks to illuminate all, or at least mainly, below the horizon line. As indicated previously, a cut-off function can be performed by one of the modules, preferably by a pixelated light projection module, and it can be a module also used for generating at least one pictogram. .

The device can also be used to form other lighting functions apart from those described above.

The invention is not limited to the embodiments described but extends to any embodiment in accordance with its spirit.

REFERENCES

1. Motor vehicle

2. Front section

3. Basic beam

4. Cut-off area

5. Pictogram writing area

6. Additional pictogram writing area

7. Pictogram

8. Contour area

10. First device

11. First module

12. Other module

20. Second device

21. Second module

22. Other module

Claims (14)

1. Vehicle lighting system (1) comprising a first projection device (10) and a second projection device (20) and configured to project at least one pictogram (7) on the ground, characterized in that the pictogram is product: - or only by a portion of a first pixelated light beam coming from at least one first module (11) of pixelated light projection located in only one of the first projection device (10) and the second projection (20); or - either by a portion of a first pixelated light beam coming from at least a first pixelated light projection module (11) located in one of the first projection device (10) and the second projection device ( 20) and by a portion of a second pixelated light beam from at least one second pixelated light projection module (21) located in the other of the first projection device (10) and the second projection device (20), the light intensity of the portion of the second beam being strictly less than that of the portion of the first beam, and in that the at least one first module (11) for pixelated light projection comprises at least one matrix of monolithic electroluminescent elements. 2. System (1) according to the preceding claim, configured to produce a contour zone (8), surrounding the pictogram (7), the light intensity of the contour zone (8) being strictly less than that of the pictogram (7 ). 3. System (1) according to the preceding claim, in which the light intensity of the second pixelated light beam is identical in the portion of said second beam and in the contour area (8), and in which the light intensity of the first Pixelated light beam is weaker in the contour area (8) than in the portion of said first pixelated light beam. 4. System (1) according to one of the two preceding claims, in which the contour zone (8) is surrounded by a context zone, the light intensity of the context zone being strictly greater than that of the zone contour (8). 5. System (1) according to one of the preceding claims, in which the light intensity of the portion of the second pixelated light beam is at least 50% lower than that of the portion of the first pixelated light beam. 6. System (1) according to one of the preceding claims, in which the at least one second module (21) for pixelated light projection comprises at least one matrix of monolithic electroluminescent elements. 7. System (1) according to one of the preceding claims, in which at least one of the first projection device (10) and the second projection device (20) comprises at least one additional projection module (12) of pixelated light configured to produce an additional beam of pixelated light producing, at least in part, on the ground, an additional pictogram distinct from the pictogram (7). 8. System (1) according to one of the preceding claims, in which at least one of the first projection device (10) and the second projection device (20) comprises at least two pixelated light projection modules, the corresponding pixelated light beam being obtained from the combination of two elementary beams of pixelated light each coming from a different one of the at least two pixelated light projection modules. 9. System (1) according to one of the preceding claims, in which at least one of the first projection device (10) and the second projection device (20) comprises at least one module (12, 22) of projection of another light beam. 10. System (1) according to the preceding claim, in which the pictogram (7) is located at least partially in a zone of superposition of the first pixelized beam and the other beam. 11. System (1) according to one of the two preceding claims, in which the other light beam is a basic beam of low beam. 12. System (1) according to the preceding claim, in which the first beam of pixelated light forms at least in part a beam of additional low beam. 13. Vehicle equipped with at least one system according to one of the preceding claims. 14. Vehicle according to the preceding claim, wherein the first projection device (10) and the second projection device (20) are arranged on a different side, among a right side and a left side, of a front or '' a rear part of the vehicle.