FR3048845A1 - LIGHTING AND / OR SIGNALING DEVICE FOR MOTOR VEHICLE - Google Patents

Abstract

A semiconductor light source (1) comprises at least a substrate (10) and a plurality of light-emitting rods (8) of sub-millimeter dimensions which extend from the substrate forming at least a first group (40) and a second group (42) of rods arranged on either side of a boundary line (44). According to the invention, the first group of rods (40) is driven to emit white light, while the rods of said second group (42) are configured to emit light of at least one color distinct from white light.

Description

The invention relates to the field of lighting and / or signaling, in particular for motor vehicles. BACKGROUND OF THE INVENTION It relates more particularly to a light source and a light device, for lighting and / or signaling of a motor vehicle, and comprising such a light source and optical shaping light rays emitted by this source.

A motor vehicle is equipped with headlamps, or headlights, intended to illuminate the road in front of the vehicle, at night or in the case of reduced luminosity. These headlamps can generally be used in two lighting modes: a first "high beam" mode and a second "low beam" mode, while the "high beam" mode provides strong illumination of the road far ahead of the vehicle. . The "low beam" mode provides more limited road lighting, but still offers good visibility without dazzling other road users.

In order not to dazzle other road users, there is provided a Code beam, specific to the "dipped beam" mode, which has a straight cut forming a substantially horizontal upper edge. This cut can have a stepped shape to present a low cut in the area in which other road users are theoretically located and an upper part allowing in this context of low beam to illuminate a little further the road scene. outside this area. These cuts, which generate a strong contrast between the illuminated area and the rest of the road scene, can in particular be achieved by means of a cache disposed on the path of the rays between the light source and the optics of bet in shape. These cuts extend essentially horizontally.

A strong contrast between a lighted area and a darkened area may also be needed in vertical beam splitting, which is selectively activated and deactivated to provide an adaptive beam that can darken a portion of the beam in which detected a vehicle whose dazzle does not want to be dazzled.

When the shaping optics comprises a lens, it is possible to observe in the projected light beam 100 the formation of a colored halo 102 in the vicinity of the cutoff edge 104, as can be seen in FIG. predominant color blue, red or green with shades, the dominant color of this colored halo being determined according to the position of the light source relative to the object focus of the lens caused to deflect the light rays emitted by the source for the project to infinity in front of the vehicle, or behind it depending on the area of application.

This creates a chromatism, that is to say an alteration of colors, in the beam projected by the projector. This chromaticism is particularly visible in a Code beam, and particularly annoying since in the middle of the driver's field of vision. This phenomenon is exerted in other types of cut-off beams generated by the use of modern projectors, and for example in beams where the cut is vertical, unlike the beam Code mentioned above where the cut is horizontal. As has been presented above for matrix beams, wherein the beam is segmented into vertical bands generated respectively by selectively activatable light sources and where the extinction of such or such source to create a dark band in the beam is controlled according to the detection of a vehicle in the road scene, a colored halo can be formed at the cut, in the band supposed to remain dark.

Mechanical means are used to try to correct these optical aberrations, by modifying constituent elements of the lighting and / or signaling device, and for example by modifying the thickness of the cache or by making it mobile, or by modifying the optical surface of the lens so that they have appropriate foci to avoid the problem presented above. These means require a complex focus.

The present invention aims to provide a light source generating a smaller colored light halo, to limit the inconvenience of the driver or road users.

An aspect of the invention relates to a semiconductor light source and a lighting and / or signaling device comprising such a source and an optical shaping light rays emitted by this source, in particular for the emission of light beam in a motor vehicle.

The light source comprises at least one substrate and a plurality of submillimeter sized electroluminescent rods which extend from the substrate forming at least a first group and a second group of rods, the two groups being arranged on one side and on the other. the other of a demarcation line, which may be curved or rectilinear. The first group of rods is driven to emit light of a first color, while the rods of said second group are configured to emit light of at least one color distinct from that first color. This first color can be white, or any other color.

According to various features of the invention, taken alone or in combination, it can be provided that: - the rods of the second group are arranged to emit a predominantly red and / or blue and / or green color; the wavelength of the lights emitted by the rods of the first group, the rods of the first wave of the second group and the rods of the next wave or waves of the second group progressively evolves; the sticks of the second group are arranged so that a first wave of sticks emits two of the three colors and a second wave of sticks emits one of the three colors; the first wave of sticks of said second group can in this case be directly in the vicinity of the demarcation line and the second wave of sticks of said second group can then be arranged in withdrawal of the first wave of rods of said second group relative to the demarcation line ;

It is understood that wave rods means a series of several pixels, and a pixel is formed by the smallest selectively activatable unit, namely one or more neighboring rods.

Several variants may be provided so that the rods of the second group may emit different colors: in particular these rods may be made of different materials, or they may be identical to each other and covered with a filter, the use of this filter to obtain the desired color of the rays emitted by at least a portion of these rods of the second group, this filter may be a tinted filter disposed on the path of the light rays emitted by these rods of the second group.

According to a characteristic of the invention, the light source comprises a third group of rods which extends beyond the rods forming said second group, that is to say that there is successively the first group of rods , the second group of sticks then the third group of sticks. The sticks of this third group are configured to emit light of a white color or corresponding to a shade of white. For example, it will be possible for the rods of the first group to be configured, in particular in intensity, to emit a regulatory code beam, and for the rods of the third group and the first group to be configured to transmit a Route beam together, the rods of the second group. group being driven to emit white rays when the rods of the first and third groups are activated simultaneously, in order to participate in the formation of a regular Route beam, or to emit green, blue or red component rays when only the rods of the first group are activated and that it is necessary to correct the chromaticism appearing beyond the cut of the beam Code.

It may be provided, in particular to adapt to the formation of a particular chromatic color and thus be able to emit a color complementary to that color of chromaticism, that the rods of the second group are selectively activatable. individually or in batches of sticks, it being understood that it means that one or more rods of the light source can be controlled to play on their light intensity. A separate ignition control system is provided for these sticks, it being understood that this is primarily intended to mean that the sticks can be switched on or off distinctively from each other, simultaneously or not, and that these sticks can be controlled for emit rays of different color from the color of the rays emitted by a neighboring stick.

According to one characteristic of the invention, the white light of the beams emitted by the first and possibly the third group of rods is produced by means of a luminophore arranged in the vicinity of the light source.

In particular, it may be provided that the semiconductor light source comprising a plurality of electroluminescent rods of submillimeter dimensions further comprises a layer of a polymeric material in which the rods are at least partially embedded; this polymeric material may be based on silicone, it being understood that the polymer material is silicone-based since it comprises for the most part silicone, for example at least 50% and in practice approximately 99% · The layer of polymer material may comprise a phosphor or a plurality of phosphors excited by the light generated by at least one of the plurality of rods. The term phosphor, or light converter, and for example a phosphor, the presence of at least one luminescent material designed to absorb at least a portion of at least one excitation light emitted by a light source and to convert to at least a portion of said excitation light absorbed into an emission light having a wavelength different from that of the excitation light. This phosphor, or this plurality of phosphors, may be at least partially embedded in the polymer or disposed on the surface of the layer of polymeric material. The set of electroluminescent rods can extend from the same substrate, and these rods can in particular be formed directly on this substrate. It can be provided that the substrate is based on silicon or silicon carbide. It is understood that the substrate is based on silicon since it comprises mainly silicon, for example at least 50% and in practice about 99% · Thus, it is possible to reduce the costs of obtaining the device according to the invention. the invention, since the silicon wafers used can be up to 12 inches in size, up to a maximum of 4 inches for the corundum used previously.

According to characteristics specific to the constitution of the electroluminescent rods and the arrangement of these electroluminescent rods on the substrate, provision can be made for each characteristic that can be taken alone or in combination with the others: each rod has a generally cylindrical shape, in particular polygonal seetion; it can be expected that each rod is the same general shape, including a hexagonal shape; the rods are each delimited by an end face and by a cireferential wall which extends along a longitudinal axis of the rod defining its height, the light being emitted at least from the eireferential wall; this light could also be emitted by the terminal face; each stick may have a terminal end which is substantially perpendicular to the circumferential wall, and in different variants, it may be provided that this terminal faee is substantially flat or curved, or pointed, at its center; the rods are arranged in a two-dimensional array, whether this matrix is regular, with a constant spacing between two sticks of a given alignment, or that the rods are arranged in a quineone; it is understood that in the case of two-dimensional matrices, the waves of rods may be considered as rows of rods; the height of a stick is between 1 and 10 meters; the largest dimension of the end face is less than 2 micrometers; the distance separating two immediately adjacent rods is at least equal to 2 micrometers, and at most equal to 100 micrometers.

As mentioned above, the invention also relates to a lighting and / or signaling device comprising a light source as described above, as well as an optical shaping of the rays emitted by the light source for emitting a light beam outside the device, said shaping optics comprising at least one lens.

By optical shaping means means for changing the direction of at least a portion of the light rays. This optical shaping can consist of one or more reflectors, or a lens, or a combination of these two possibilities. The shaping optics may be arranged to present a source focus not centered on the light source. This makes it possible in particular to emit an image that appears continuous, in direct imaging, without the need to provide a system to modify the source image before being issued. This is particularly interesting for simplifying the proposed device. in particular when one or more separation walls are arranged projecting from the substrate in order to participate in the optical pixelation of the projected regulatory beam.

Thus, the automotive field is applied to the technology of making the light-emitting zone by a forest of electroluminescent rods that is grown on a substrate, to produce a three-dimensional topology. It will be understood that this three-dimensional topology has the advantage of multiplying the light emission surface with respect to the electroluminescent diodes known hitherto in the automobile field, namely substantially planar diodes. In this way, it is possible to provide at low cost a very bright white light.

It may be provided that the device further comprises detection means configured to detect chromaticity in the projected beam and means for analyzing the information recorded by said detection means to qualify the dominant color of said chromatism, as well as control means capable of generating an instruction for driving at least one rod of the second group so that it emits a light of a color complementary to the dominant color of said chromatism.

These detection means may be configured to detect a plurality of zones in the colored halo and the control means may be able to generate a plurality of waveguide driving instructions of the second group for each wave to emit light. a color complementary to the color of an area of the colored halo.

According to a particular characteristic of the invention, it is provided that the light source ensures the generation of light rays which form at least one regulatory light beam for a motor vehicle. By regulatory beam is meant a beam that respects one of the pbotometric grids shown in the figures.

The device thus takes place in a projector before as well as in a rear light of a motor vehicle. The invention also relates to a method of chromatic correction of a cut-off beam projected by a lighting and / or signaling device comprising at least one rod light source and a lens, during which the emission is generated. at least one color of light by rods of the source arranged in the vicinity of an edge defining the cutoff of the projected beam.

The method of the invention may comprise other steps, including the step in which the first step is to detect a hue of the beam projected on either side of the cut-off of this beam, as well as the one during which a color characteristic of a colored halo on one side of this cut is determined and in which at least a portion of the rods of the light source are selectively activated in the vicinity of the demarcation line in the light source so that they emit color rays able to compensate for the characteristic color detected of the colored halo, and in particular to carry out by additive synthesis a regulatory white, as will be defined hereinafter.

It can be envisaged that the position of the light source with respect to the object focus of the lens is identified and that the rods of a first wave arranged in the direct vicinity of the demarcation line are commanded to emit rays of light of a predetermined color according to said position of the source.

In particular, when the rod light source has been identified as present on a red object focus of the lens, it is possible to order the rods of a first wave arranged in the direct vicinity of the demarcation line so as to emit rays of light red, as well as the rods of a second wave set back from the demarcation line with respect to said first wave so as to emit rays of red and green light.

When the rod source has been detected as present on the "blue" object focus of the lens, the rods of the second group are piloted so that the first wave of rods will emit blue rays, and the second wave of rods will emit blue and green rays.

When the rod source has been detected as present on the "green" object focus of the lens, a green emission is produced on at least one of the two waves of rods, and preferably on both waves. Other features and advantages of the present invention will appear more clearly with the aid of the description and the drawings in which: FIG. 1 is a schematic representation of a cut-off beam, here a beam Code, and of the zone in border of the cut in which chromaticism can be detected; Figure 2 is a schematic representation of the optical phenomenon generating a chromatism at the cutoff of the beam Code; FIG. 3 is a sectional view of a lighting and / or signaling device according to one embodiment of the invention, in which light rays emitted by a semiconductor light source according to FIG. invention in the direction of a shaping optics; FIG. 4 is a schematic perspective view of the semiconductor light source of FIG. 3, in which a row of light emitting rods has been made visible in section; Figure 5 is a sectional view of a particular embodiment of the invention, wherein two electroluminescent rods protrude from a substrate, said electroluminescent rods being encapsulated in a protective layer; Figures 6 and 7 are top views of a light source and electroluminescent rods, in which different groups of rods have been illustrated; and Figure 8 corresponds to a cbromaticity diagram on which is represented the regulation blank area set for calculating the color to be emitted by the groups of sticks.

FIGS. 1 and 2 show a beam emitted outside a lighting and / or signaling device, comprising a shaping optics comprising at least one lens. It is understood that the lens is used to emit at infinity a beam substantially parallel to the optical axis, an image of the light source when it is positioned at the object focus of the lens. However, the lens used in the shaping optics can not be an ideal thin lens and because of its thickness, this lens behaves like a prism, with foci objects slightly offset for each of the colors to be transmitted. According to the exact position of the light source, on one or other of the foci specifically associated with one of the colors, it is understood that the corresponding images form infinitely more or less large tasks.

This phenomenon is illustrated in particular in FIG. 2, with a lens 106 comprising three foci, blue FBL, red FRL and green FGL, all arranged on the optical axis of the lens, and a light source 108 that has been arranged. on the FRL red object focus of lens 106. The red focus is farthest away, the blue focus is closest to the center of the lens, and the green focus is in between.

In the case illustrated by way of example, the light source is centered on the red focus of the lens, so that the red rays emitted by the light source, in particular to provide the white light at the output of the device, are emitted substantially parallel to the optical axis of the lens. The projected image was represented by three concentric tasks 110, centered on the optical axis of the lens. Since the light source is arranged on the red object focus, the rays form at infinity a concentrated task, not very diffused around the axis. The blue rays, due to the farther position of the source with respect to the blue focus, are diffused to infinity by flaring off the optical axis, so that it forms on the projected image illustrated on the figure 2 a balo wider than the balo formed by the red rays, more concentrated. And we understand that because of the intermediate position of the green object focus of the lens, the balo formed by the green rays from the light source centered on the red focus takes an intermediate size between the small balo formed by the red rays and the great balo formed by the blue rays.

In this way, the first concentric circle 110c is formed by red, green and blue rays and forms a non-penalizing white light, while the second and third concentric circles are not impacted by the red rays and thus form a colored beam , entirely blue for the 110th outer circle and blue-green for the middle circle llOi.

In a cut-off beam, it is understood that a part of the blue and blue-green stain forms a colored ball beyond the cut-line, it being understood that the halo could take on different colors if the source were arranged on another focus object lens color.

A lighting and / or signaling device of a motor vehicle comprises a light source 1, in particular housed in a casing 2 closed by a lens 4 and which defines an internal receiving volume of this emitter device. The light source is associated with an optical shaping of a portion of at least a portion of the light rays emitted by the semiconductor source. As has been previously stated, the shaping optics change a direction of at least a portion of the light rays emitted by the source.

The light source 1 is a semiconductor source, comprising electroluminescent rods of submillimetric dimensions, that is to say, semiconductor sources in three dimensions as will be explained hereinafter, unlike conventional sources in two dimensions, assimilated to substantially flat sources because of their thickness of the order of a few nanometers while a light emitting rod source has a height at least equal to one micrometer.

The light source 1 comprises a plurality of electroluminescent rods 8 of submillimeter dimensions, which will be called thereafter electroluminescent rods. These electroluminescent rods 8 originate on the same substrate 10. Each electroluminescent rod, here formed by use of gallium nitride (GaN), extends perpendicularly, or substantially perpendicularly, projecting from the substrate, here made of silicon, d Other materials such as silicon carbide can be used without departing from the context of the invention. By way of example, the electroluminescent rods could be made from an alloy of aluminum nitride and gallium (AIGaN), or from an alloy of aluminum, indium and gallium (AlginGaN) .

In FIG. 4, the substrate 10 has a lower face 12 on which a first electrode I4 is connected, and an upper face I6 projecting from which the electroluminescent rods 8 extend and to which a second electrode I8 is attached. Different layers of materials are superimposed on the upper face 16, in particular after the growth of electroluminescent rods from the substrate obtained here by an ascending approach. Among these different layers, one can find at least one layer of electrically conductive material, in order to allow the power supply of the rods. This layer is etched so as to connect a particular rod between them, the ignition of these rods can then be controlled simultaneously by a control module not shown here. It can be provided that at least two electroluminescent rods or at least two groups of electroluminescent rods of the semiconductor light source 1 are arranged to be lit separately by means of an ignition control system. .

The submillimetric electroluminescent rods extend from the substrate and comprise, as can be seen in FIG. 4, a gallium nitride core 19 around which are disposed quantum wells 20 formed by a radial superposition of layers of different materials, here gallium nitride and gallium-indium nitride, and a shell 21 surrounding the quantum wells also made of gallium nitride.

Each rod extends along a longitudinal axis 22 defining its height, the base 23 of each rod being disposed in a plane 24 of the upper face I6 of the substrate 10.

The electroluminescent rods 8 of the semiconductor light source advantageously have the same shape. These rods are each delimited by an end face 26 and a circumferential wall 28 which extends along the longitudinal axis. When the electroluminescent rods are doped and polarized, the resulting light at the output of the semiconductor source is emitted mainly from the circumferential wall 28, it being understood that it can be expected that light rays also emerge, at least in small amounts, from the end face 26. As a result, each rod acts as a single light-emitting diode and the density of the electroluminescent rods 8 improves the light output of this semiconductor source .

The circumferential wall 28 of a rod 8, corresponding to the gallium nitride shell, is covered by a transparent conductive oxide (OCT) layer 29 which forms the anode of each rod complementary to the cathode formed by the substrate. This circumferential wall 28 extends along the longitudinal axis 22 from the substrate 10 to the end face 26, the distance from the end face 26 to the upper face 16 of the substrate, from which the electroluminescent rods 8 originate. , defining the height of each stick. For example, it is expected that the height of a light emitting rod 8 is between 1 and 10 micrometers, while it is expected that the largest transverse dimension of the end face, perpendicular to the longitudinal axis 22 of the electroluminescent rod concerned, ie less than 2 micrometers. It will also be possible to define the surface of a rod, in a cutting plane perpendicular to this longitudinal axis 22, in a range of determined values, and in particular between 1 and 5 microns square.

These dimensions, given by way of non-limiting example, make it possible in particular to demarcate a semiconductor light source comprising electroluminescent rods of a light source of substantially flat diode sources as used previously.

It is understood that during the formation of rods 8, the height can be changed from one light source to another, so as to increase the luminance of the semiconductor light source when the height is increased. The height of the rods may also be modified within a single light source, so that one group of rods may have a height, or heights, different from another group of rods, both groups being the semiconductor light source comprising electroluminescent rods of submillimeter dimensions.

The shape of the electroluminescent rods 8 may also vary from one device to another, in particular on the section of the rods and on the shape of the end face 26. FIG. 4 shows electroluminescent rods having a generally cylindrical shape. , and in particular of polygonal section, here more particularly hexagonal. It is understood that it is important that light can be emitted through the circumferential wall, that it has a polygonal or circular shape for example.

Moreover, the end face 26 may have a substantially planar shape and perpendicular to the circumferential wall, so that it extends substantially parallel to the upper face 16 of the substrate 10, as shown in FIG. 4, or although it may have a domed or pointed shape at its center, so as to multiply the directions of emission of the light exiting this end face, as shown in FIG.

In Figure 4, the electroluminescent rods 8 are arranged in two-dimensional matrix. This arrangement could be such that the electroluminescent rods are arranged in staggered rows. The invention covers other distributions of the rods, including rod densities which can be variable from one light source to another, and which can be variable in different areas of the same light source. FIG. 4 shows the separation distance d1 of two immediately adjacent electroluminescent rods in a first transverse direction and the separation distance d2 of two immediately adjacent electroluminescent rods in a second transverse direction. The separation distances d1 and d2 are measured between two longitudinal axes 22 of adjacent electroluminescent rods. The number of electroluminescent rods 8 projecting from the substrate 10 may vary from one device to another, in particular to increase the light density of the light source, but it is appropriate that one or the other of the distances dl, d2 separation must be at least equal to 2 micrometers, so that the light emitted by the circumferential wall 28 of each electroluminescent rod 8 can exit the matrix of rods. Furthermore, it is expected that these separation distances are not greater than 100 micrometers.

The light source 1 may further comprise, as shown in FIG. 5, a layer 30 of a polymeric material in which electroluminescent rods 8 are at least partially embedded. Coucbe 30 can thus extend over the entire extent of the substrate or only around a given group of electroluminescent rods 8. The polymer material, which can be silicone-based, can protect electroluminescent rods 8 without disturbing the diffusion of light rays. In addition, it is possible to integrate in this layer 30 of polymeric material wavelength converting means, and for example phosphors, able to absorb at least a portion of the rays emitted by one of the rods and to converting at least a portion of said absorbed excitation light into an emission light having a wavelength different from that of the excitation light. It can be provided without distinction whether the wavelength conversion means are embedded in the mass of the polymeric material, or that they are arranged on the surface of the layer of this polymeric material.

The light source may further comprise a coating 32 of light reflective material which is disposed between the electroluminescent rods 8 to deflect the rays, initially oriented towards the substrate, towards the end face 26 of the electroluminescent rods 8. In other words the upper face 16 of the substrate 10 may comprise a reflecting means which reflects the light rays initially oriented towards the upper face 16 towards the exit face of the light source. This recovers rays that otherwise would be lost. This coating 32 is disposed between the electroluminescent rods 8 on the transparent conductive oxide layer 29.

The light source 1 here comprises a rectangular shape, but it will be understood that it can present without departing from the context of the invention other general shapes, and in particular a form of parallelogram.

A separation 34 between two electroluminescent rods or two groups of electroluminescent rods can be provided so as to split the beams that can be emitted by this three-dimensional light source. This separation 34, embodied for example by a dotted line in FIG. 4, can be obtained by the physical embodiment of a wall projecting from the substrate, but it is first of all carried out by the determined wiring of a particular electroluminescent rod 8 between them.

In the lighting and / or signaling device according to the invention, as illustrated in FIG. 3, the shaping optics 6 consist of a lens 36 which deflects the rays emitted by the light source arranged at focus object of the lens to form a beam to infinity regulatory, that is to say, which respects the gate of a particular lighting beam and / or signaling. A mask 38 may be provided between the light source 1 and the lens 36 to deflect the rays towards the lens, it being understood that the three-dimensional shape of the semiconductor light source according to the invention generates emissions. of light rays in different directions.

As has been explained above, the presence of a lens 36 can generate the formation of colored halo at the cut. The correction of this chromatism, which is the subject of the invention, is notably achieved by a particular arrangement of the rods of the light source and by specific ignition control means of some of these rods.

Reference will be made hereinafter to the case illustrated in FIGS. 1 and 2, in which the colored halo 102 formed at the cutoff 10O of the beam is predominantly blue, because of the position of the light source 10B with rods on the object hearth FRL red of the lens, or at least in close proximity to this FRL red object focus of the lens, it being understood that the device according to the invention is configured to easily adapt to each dominant color of the colored halo by adequate control sticks.

As a reminder, in the case illustrated by way of example, the light source IO8 is centered on the red focal point FRL of the lens 106, so that the red rays are concentrated in a more concentrated task than the task corresponding to the green ray. itself more concentrated than the task corresponding to the blue ray. Thus the image projected to infinity by this source takes the form of three concentric circles. A first circle 110c, of smaller size and focused on the optical axis, has a white color, formed by the combination of red and green color tasks, while a second blue-green intermediate ring IlOi is formed. by the combination of green and blue color tasks in the absence of the red color, and that a third 110e outer ring of blue color is formed by the only blue color because of the absence of the red color and the color green. In this case, the object of the invention is first of all to compensate the blue color of the outer ring by a red and green color emission, so that the combination of the whole forms a white light and, on the other hand, to compensate. the blue-green color of the intermediate ring by a red emission, so again to form a white light, likely to less distract the driver.

Control instructions are sent to some rods to emit a red light, and to other rods to emit red and green light. And in this case, since the green color, in this position of the source on the red focus, emits a larger bright spot than that generated by the red color, we need more rods emitting red light in order to spread the red light emitted and manage to compensate for the entire blue and blue-green halo.

The plurality of submillimeter-sized electroluminescent rods 8 provided by the semiconductor light source 1 is arranged from the substrate forming at least a first group 40 and a second group 42 of rods arranged on one side and the other These two groups of rods are defined in particular by a separate electrical connection, which allows a selective control of the first group of rods 40 with respect to the second group of rods 42, and the rods of the second group 42 are selectively activatable between them, i.e. sticks of the second group can be controlled independently of other rods of the second group.

The first group of rods 40 is driven to emit white light rays, while the second group rods 42 are configured to emit light of at least one color distinct from the white light. In particular, the rods of the second group are configured to emit rays of red and / or blue and / or green. It is the ignition of these sticks of the second group 42, and their specific control with respect to each other which allows according to the invention to correct the chromaticism that may appear in the cut-off beam.

In FIG. 6, a light source 1 is partially seen from above to make several waves of rods 8 visible and to illustrate the selective control of some of these rods as a function of their position with respect to a demarcation line 44.

A first group of rods 40 is disposed on one side, here above in the arbitrary orientation of FIG. 6, of a right portion of the dividing line 44 separating this first group of rods from a second group of rods 42. When it is desired to form a code beam, only the rods of the first group 40 are ignited, and the cutoff of the projected beam is defined by the presence of this demarcation line 44 on the source and the fact that no stick beyond this demarcation line is activated.

The rods 8 of the first group 40 are configured to emit only white light, for example by means of RGB semiconductors, that is to say emitters capable of emitting red, green, and blue, which are driven to emit white, or for example by means of semiconductor emitting blue and that the phosphor embedded in the layer of encapsulating material participates in converting white light.

On the other side of the demarcation line 44, the rods 8 of the second group 42 are configured to participate in the formation of a red, green, or blue light beam. For example, it can be provided that the rods of the second group are made of different materials to emit different colors, and the rods corresponding to the color that one wishes to emit in this second group will be activated. It is also possible to provide similar rods between them and for example formed by RGB semiconductors that are piloted to emit one of these colors, or two of these colors. It is also possible to provide sources that emit white light and a tinted filter arranged in the path of the rays, advantageously between the source and the lens.

In the second group of rods 42, there are two consecutive waves, namely a first wave 46 of rods directly adjacent to the demarcation line 44 and a second wave 48 of rods set back from it with respect to this dividing line. .

In the case of a light source formed of a matrix of electroluminescent rods in two dimensions, this first wave 46 and this second wave 48 of rods 8 may be considered as rows of rods extending parallel to the demarcation line 44 and of a constant thickness along this demarcation line, one or more rods 8. Advantageously, in order to control more precisely the colors to be emitted to correct the chromatism, the number of rods determining the thickness of the first wave 46 is equal to the number of rods determining the thickness of the second wave 48.

At least in the cases where the light source is placed on the FRL red object focus or on the FBL blue object focus, the second group sticks 42 are controlled so that the first wave of sticks 46 emits two of the three colors and that a second wave of rods 48 emits one of the three colors, being reminded that the first wave of sticks of said second group is directly in the vicinity of the demarcation line 44 while the second wave of sticks 48 of said second group is arranged in withdrawal of the first wave of rods 46 of said second group with respect to the demarcation line.

In the example given in reference where the light source is positioned on the red object focus FRL of the lens 36, the rods of the second group 42 are controlled to emit color rays complementary to the blue of the third outer ring 110e and complementary to the blue-green of the second intermediate ring llOi. The first wave of rods 46 receives control instructions for the emission of green and red color rays and the second wave of rods 48 receives control instructions for the emission of only red-colored rays. Two waves of rods are thus driven to obtain red and a single wave to obtain green, which is understood by the fact that in this case we need more rods emitting red light in order to spread the light. red emitted and manage to compensate the entire blue ball while the green color produces a more diffuse task since the source is positioned on the red object focus of the lens.

As described in the previous embodiment, the rods 8 of the second group 42 may be RGB diodes that can emit in each of the three primary colors, so that they can emit white. Therefore, when the set of rods is activated for the formation of a homogeneous road beam, we can order the rods of the second group so that they emit white light like the rest of the rods of the source.

In order to control the activation of the various rods and to control the emission of determined colors in the projected beam, the lighting and / or signaling device comprises means for calculating an appropriate command command of the ignition rods, depending on a position of the light source and a dominant color of the chromaticism at the edge of the beam cutout resulting therefrom, and control means configured to format and transmit the control instructions to the different rods to drive.

The device may further comprise detection means configured to detect in real time a chromatism in the projected beam and a dominant color of this chromatism, and to send this information to the calculation means. A learning step, or in other words calibration, may be necessary in the workshop to define the conditions. in particular of contrast between the illuminated zone and the dark zone on both sides of the cut of the beam, corresponding to the appearance of a colored ball.

It is understood that in the case of a real-time detection, the detection means and the calculation means are embedded on the vehicle, but that it could be expected that this setting is made once only at the exit of the chain of manufacturing and that these means are only provided in the workshop, driving the sticks of the second group is then systematic when a beam Code is projected. By way of non-limiting examples, provision may be made for the detection means to consist of one or more cameras associated with one or more filters when the means are on board the vehicle, whereas they may consist of a spectrocolorimeter when they are fixed in the workshop.

We will now describe, relying in particular on the illustration in Figure 7> an alternative embodiment that differs from what has been previously described in particular in the form of the demarcation line and therefore in the form of rods waves to be controlled in the vicinity of this demarcation line, and also in the number of distinct groups of rods of the light source. It will be understood that the light source could, without departing from the context of the invention, include one or more of these differences with respect to the initial embodiment.

The light source comprises here a third group of rods 50 arranged so that the rods forming the second group 42, that is to say the rods 8 whose ignition intensity is controlled to emit rays of a color determined to correct the chromatism, are sandwiched between the rods of the first group 40 and the rods of the third group 50. As before, the rods forming the second group 42 are arranged on the other side of the demarcation line 44 relative to the first group of rods, and it is understood that the third group of rods 50 extends on the same side of the demarcation line 44 as the second group of rods 42.

This third group of rods 50 is configured to emit white light, and to form a homogeneous beam with the white light emitted by the first group. The luminous intensity of the white light emitted by the third group of rods is greater than the luminous intensity emitted by the rods of the second group so that when all the rods of the source are activated, the color emitted by the rods the second group is embedded in the white color emitted by the third group of sticks.

This configuration is particularly interesting for producing with a single light source at a time a beam Code, when only the rods of the first group are activated, the rods of the second group can be activated to correct the chromaticism of the beam

Code in the vicinity of the cut edge, and a crossing beam, when the set of sticks is activated.

As described in the previous embodiment, the rods of the second group may be RGB semiconductors which can emit in each of the three primary colors, so that it is possible for these rods to emit white. Therefore, when the set of rods is activated for the formation of a homogeneous road beam, we can order the rods of the second group so that they emit white light like the rest of the rods of the source.

Moreover, as evoked, it is notable that the demarcation line 44 differs from that illustrated in the previous embodiment, in particular in that it has a staircase shape similar to that which one wishes to give the Cut-off beam to avoid dazzling the road users and keep a good lighting of the sides. We understand that the first and second wave of rods of the second group take a corresponding form.

More generally, we can consider foci of other colors than red, green and blue. These are generally juxtaposed in order red, orange or amber, yellow, green, blue, indigo, purple, from the farthest to the nearest lens. This order may vary depending on the structure of the lens, depending on whether it is convergent, divergent, or of complex structure such as for example a doublet of contiguous lenses, well known to those skilled in the art. The sources can have colors chosen among all those or even various colors of these different colors. The number of colors and / or hues used is not limited to three but could be two, four, five or more. The number of waves formed by the rods of the second group is then adapted according to the number of colors or hues used. The advantage of increasing this number is to be able to fine-tune the chromatic correction. Each group is ordered to emit a choice of colors or hues able to correct the chromaticism in the zone of the corresponding beam.

In another embodiment not shown, the emitted beam is provided to have a color other than white, for example red or amber. The light sources are then configured so that, along at least one edge of the beam, their colors or tints add up to compensate for the undesirable chromaticism, so that in this zone the color corresponds to that intended for the beam.

We will now describe a method of using such a light emitting rod light source in a lighting and / or signaling device for the emission of a regulatory beam of a motor vehicle, which can correct the chromaticism a projected cut-off beam, in particular by the choice of the appropriate color to be projected by rods of the source arranged in the vicinity of a corresponding demarcation line on the source at the cut in the projected beam.

Whether in a production line, for a definitive static adjustment with acquisition means that can be deported, or while driving, for real-time dynamic adjustment with on-vehicle acquisition means first, the detection of a hue of the beam projected on either side of the cut-off of this beam is carried out. The associated detection means are configured to acquire an image of the road scene at the height of the beam cutoff, and this image is transmitted to calculation and analysis means configured to give information on a characteristic color or hue. a colored halo extending from the dark side of this cut. This information is transmitted to control means of the light source which gives instructions for selectively controlling at least a portion of the rods of the light source to emit rays of color or hue capable of compensating the color characteristic of the colored halo detected.

Next, theoretical examples will be described in which the position of the source on the red, green or blue object focus of the lens involves control instructions for igniting the rods of this source to selectively emit red, and / or blue and / or green.

In general, the control means determines the color of the rays to be emitted to compensate for the characteristic color of the colored halo detected by using a bromaticity diagram, as illustrated in FIG. 8. The colors are represented on such a diagram according to their coordinates x and y, and we can observe more particularly on this diagram a representation of the "spectrum locus" 52 and the "regulatory blank zone" 54 ·

The "spectrum locus" 52 is a curved line on which the pure colors are arranged in the order of their characteristic wavelength. The pure color of blue tint is arranged at one end of the spectrum locus and the pure colors of cyan, green, yellow, amber and red color succeed each other one after the other. Within this spectrum locus, the different colors arising from each of the hues are placed according to their saturation, that is to say their purity, by approaching in the center of the diagram an area in which they tend to white.

The "prescribed white area" 54 corresponds to the variations in white, in the limit of the purest colors of each of the shades, that the regulation specific to the daytime and / or night lighting of motor vehicles has defined and that the car manufacturers must respect to see their vehicles approved and marketable. This area of regulation whites is defined by the edges and inside of a hex whose six sides have the following characteristic equations:

First side 56, said limit side of the blue hue: X = 0.310

Second 58 and third 60 side, said boundary sides of the green tint: y = 0.150 + 0.640 X and y = 0.440

Fourth side 62, said limit side of the yellow hue: X = 0.500

Fifth side 64, said limit side of the red hue: y = 0.382

Sixth side 66, said limit side of purple or purple hue: y = 0.050 + 0.750 X

The vertices of the polygon respectively have for a pair of coordinates (x, y):

P1 (0.310, 0.348), P2 (0.310, 0.283), P3 (0.443, 0.382), P4 (0.500, 0.382), P5 (0.500, 0.440), P6 (0.453, 0.440).

The calculating means determine the coordinates of the color or hue detected in the colored ball, by processing the information received from the detection means, and they compute a calculation to determine which are the coordinates of the hue or hues to be emitted for to obtain by additive synthesis a regulatory blank, that is to say one of the variations of the authorized blanks.

It is thus possible to adapt to the position of the light source on an object focus of a given lens, regardless of the color or hue associated with this object focus.

In particular, the control instructions may consist of selective ignition of the rods directly in the vicinity of the demarcation line referenced in the light source, such as the separation between a first group of rods whose emission of light rays contributes to forming a beam Code and a second group of rods not used to form the beam Code. While the sticks identified as forming part of the first group of sticks continue to emit rays so as to emit a beam of light of a first color, this color may especially be white or a variation of white, at least a first wave rods of the second group, directly in the vicinity of the demarcation line, is controlled so as to emit rays of a light of color complementary to the detected color of the colored ball to be corrected, that is to say a color permitting by additive synthesis with the detected color of the colored halo to obtain a regulatory white. It is understood that a second wave of rods of the second group can be ordered to participate in the complementarity of the color of the colored halo, the colors of these successive waves gradually varying from the line of demarcation.

In more detail, and simplified, reference will be made thereafter to a lens having three blue, red and green objects foci.

When the rod light source has been identified as present on a red object focus of the lens, i.e. a predominantly blue colored halo appears at the beam cutting edge, the rods of the beam are distinctively controlled. second group according to whether they are part of a first wave located in the immediate vicinity of the demarcation line or a second wave located further from the demarcation line after the first wave. The rods of the first wave are controlled to emit rays of red light, while the rods of the second wave are controlled to emit rays of red and green light. A control instruction specific to each wave of rods is sent simultaneously to correct the chromatic appearing or likely to appear.

Similarly, when the rod light source has been identified as present on a blue object focus of the lens, i.e. a predominantly red colored halo appears at the beam cutoff edge, it is controlled Distinctively the sticks of the second group so as to realize a blue emission on the first wave of rods, and a emission of blue and green on the second wave of rods.

When the rod light source has been identified as present on a green object focus of the lens, it is understood that the blue and red colors forming similarly enlarged tasks and we are witnessing the formation of a predominantly purple colored halo at the cutting edge of the beam, so that one also controls the rods of the second group, both those of the first wave and the second, so as to achieve a green emission on the two waves of rods.

The present invention applies to both a front projector and a rear light of a motor vehicle. The foregoing description clearly explains how the invention makes it possible to achieve the objectives that it has set itself and in particular to propose a lighting and / or signaling device which makes it possible to obtain, by application of semi-automatic sources, conductor comprising electroluminescent rods in the field of the automobile, and by driving some of these rods arranged along a demarcation line of the rods on the light source corresponding to a cutoff of the beam projected through the this source and the lens, a uniform color of the cut beam without chromatic aberration at its periphery in particular.

Claims (15)

A semiconductor light source (1) comprising at least one substrate (10) and a plurality of submillimeter-sized electroluminescent rods (8) which extend from the substrate forming at least a first group (40) and a second group (42) of rods arranged on one side and the other of a demarcation line (44), characterized in that said first group of rods (40) is driven to emit a light of a first color, while the sticks of said second group (42) are configured to emit light of at least one color or hue distinct from said first color. 2. Light source according to claim 1, characterized in that the first group of rods is controlled to emit a color light or white shade. 3. Light source according to claim 1, characterized in that the first group of rods is controlled to emit a light of color or shade different from white. 4. Light source according to one of the preceding claims, characterized in that the rods of the second group (42) are arranged to emit a predominantly red and / or blue and / or green color. 5. Light source according to one of the preceding claims, characterized in that the rods of the second group (42) are arranged on one side of the demarcation line (44) in at least two waves controlled to respectively emit light of different wavelength. 6. Light source according to the preceding claim, characterized in that the wavelength of the lights emitted by the rods of the first group, the rods of the first wave (46) of the second group (42) and the rods of the subsequent waves of the second group (42) progressively evolve. 7. Light source according to one of the preceding claims, characterized in that the rods of the second group (42) are arranged on one side of the demarcation line (44) in two waves, so that a first wave of sticks (4b) emits two of the three colors red, blue and green, and a second wave of sticks (48) emits one of these three colors. 8. Light source according to the preceding claim, characterized in that the first wave of rods (46) of said second group (42) is directly adjacent to the demarcation line (44) and in that the second wave of rods ( 48) of said second group is arranged in withdrawal of the first wave of rods (46) of said second group with respect to the demarcation line (44) · 9. Light source according to one of the preceding claims, characterized in that it comprises a third group of rods (50) arranged such that said second group of rods (42) extends between the first group of rods ( 40) and this third group of sticks (50), which is configured to emit white light. 10. Light source according to one of the preceding claims, characterized in that at least rods of the second group (42) are selectively activatable. 11. Light source according to one of the preceding claims, characterized in that the or the white lights are emitted via a phosphor arranged in the vicinity of the light source. 12. A lighting and / or signaling device comprising a light source (1) according to one of the preceding claims, and an optical shaping (6) of the rays emitted by the light source for the emission of light. a light beam outside the device, said shaping optics comprising at least one lens (36). 13- lighting device and / or signaling according to the preceding claim, characterized in that it further comprises detection means configured to detect a colored halo (102) in a beam (100) projected and means of analyzing the information recorded by said detection means to qualify a dominant color in an area of said colored halo, as well as control means capable of generating a control instruction of at least one rod (8) of the second group (42) for it emits a light of a color complementary to the dominant color of said chromaticism. 14 · A lighting and / or signaling device according to the preceding claim, characterized in that the detection means are configured to detect a plurality of zones in the colored halo (102) and in that the control means are suitable for generating a plurality of rod wave steering instructions of the second group (42) for each wave to emit light of a color complementary to the color of an area of the colored halo. A method for correcting the chromatism of a cut-off beam projected by a lighting and / or signaling device comprising at least one light source (1) with rods and a lens (36), in which the light is generated. emitting light of at least one color by rods (8) of the light source arranged in the vicinity of an edge defining the cutoff of the projected beam. 16. Method according to the preceding claim, in which it is first carried out to detect a hue of the beam projected on either side of the cut-off of this beam, then a color of at least one color is determined. zone of a colored halo extending from one side of this cut and in which at least a portion of the rods of the light source are selectively activated in the vicinity of the demarcation line in the light source so that they emit color rays adapted to compensate for the color of said at least one area of the colored halo. 17- Method according to one of claims 15 or 16, characterized in that one identifies the position of the light source relative to the object focus of the lens and in that one controls the rods of a first wave arranged in the direct vicinity of the demarcation line so as to emit rays of light of predetermined color according to said position of the source.