EP3044501B1 - Lighting module for a vehicle - Google Patents

Description

The present invention relates to a lighting module intended to be arranged in a headlight of a motor vehicle and to a method for producing a lighting beam produced by this lighting module.

The invention also relates to a projector comprising such a lighting module.

Such a lighting module is known from the documents DE 10 2012 100 141 A1 and US 2011/0249460 A1 .

Traditionally, headlamps equip the front of motor vehicles and are capable of forming lighting beams which are capable of fulfilling different lighting functions taking into account traffic conditions, such as, for example, low beam, city lighting functions , road or anti-fog.
Known in the state of the art so-called adaptive projectors which are capable of forming advanced lighting beams, also called adaptive whose dimensions, intensity and / or direction are adjusted to fulfill such functions. These headlamps make it possible in particular to carry out the functions of directional lights, of adaptive high beams or without glare, comprising at least one zone for masking the beam in the zones where vehicles are crossed or followed.

Each projector is generally made up of several lighting modules making it possible to obtain sufficient light power in order to form a lighting beam. Each of these lighting modules then forms part of the lighting beam of the projector by being switched on or off separately from one another.

By lighting module is meant an assembly comprising at least one light source and an optical projection or reflection system.
In particular and in the context of the present invention, the light source is a laser source. The module then includes a wavelength conversion device.

This laser light source of the lighting module is capable of emitting radiation towards a scanning system such as a micro-mirror mounted mobile around two orthogonal axes.

This radiation is then diverted by this scanning system to at least one wavelength conversion device which comprises a substrate made of reflective or transparent material on which a thin layer of phosphorescent material is deposited.

It will be noted in the present text, by “phosphorescent material” is meant a material having a phosphorescent effect, generally comprising different chemical elements, but not necessarily containing phosphorus.

The conversion device, thus being scanned by the scanning system, re-emits white light radiation towards an optical projection system and thus forms part of the lighting beam of the projector.

The modules of such a projector are controlled by a control unit which controls the activation of the laser light sources and the scanning systems for carrying out the various lighting functions of the projector.

However, such a projector thus comprising several lighting modules is of a considerable size.

In addition, it is an expensive and complex design, in particular because it requires a long adjustment time and a precise configuration of these lighting modules for the configuration of the various lighting functions.

Moreover, such a projector generally produces a light beam which may have color differences due to the fact that each part of this beam is produced by each of these light modules and in particular because of the variability of the layers of phosphorescent material. from one module to another.

In addition, each lighting module equipping this projector is not very efficient compared to the nominal power of the laser sources: in fact, the rate of use of the laser power is low because during its use the laser is frequently under-watted to form a usual regulatory beam and avoid generating light points in the beam which would not meet the regulatory maximums. This is also necessary to avoid visual discomfort for the driver, linked to too strong lighting near the vehicle.

The object of the present invention is to remedy all or part of the various drawbacks mentioned above.

In this regard, the subject of the invention is a lighting module for a motor vehicle headlight according to the features of claim 1.

• la première source de rayonnement lumineux est agencée au-dessus d'un axe optique du système optique de projection ;
• la au moins première source de lumière laser est positionnée au-dessus ou en retrait du dispositif de conversion de longueur d'onde ;
• le réflecteur est positionné devant la au moins première source de lumière laser, au-dessus d'un axe optique du système optique de projection entre le dispositif de conversion de longueur d'onde et le système optique de projection ;
• le réflecteur est un miroir réalisé en métal, notamment un alliage à base d'aluminium ;
• la au moins première source de lumière laser est apte à émettre un rayonnement laser vers le réflecteur qui est apte à le diriger vers une partie supérieure de la surface du dispositif de conversion de longueur d'onde ;
• la deuxième source de rayonnement lumineux, le réflecteur et le système optique de projection sont agencés du même côté du dispositif de conversion de longueur d'onde ;
• les au moins première et deuxième sources de lumière laser sont des diodes laser, notamment des diodes laser présentant les mêmes caractéristiques.

According to other advantageous and non-limiting characteristics of the invention:

• the first source of light radiation is arranged above an optical axis of the projection optical system;
• the at least first laser light source is positioned above or behind the wavelength conversion device;
• the reflector is positioned in front of the at least first laser light source, above an optical axis of the projection optical system between the wavelength conversion device and the projection optical system;
• the reflector is a mirror made of metal, in particular an aluminum-based alloy;
• the at least first laser light source is capable of emitting laser radiation towards the reflector which is capable of directing it towards an upper part of the surface of the wavelength conversion device;
• the second source of light radiation, the reflector and the optical projection system are arranged on the same side of the wavelength conversion device;
• the at least first and second laser light sources are laser diodes, in particular laser diodes having the same characteristics.

The invention also relates to a headlight for a motor vehicle comprising a lighting module according to the invention, in particular a single lighting module according to the invention.

The last object of the invention is a method of producing a lighting beam comprising the features of claim 10.

Advantageously, it is understood that the lighting module and therefore the projector which includes it are of a design cost and a small footprint.

Indeed, this lighting module makes it possible to carry out all the lighting functions taking into account traffic conditions and the regulations in the matter, by comprising only a single wavelength conversion device and a single projection optical system. Thus and advantageously, the beam generated is homogeneous in color and a precise superposition of the different parts of the beam is carried out without requiring mechanical adjustment between modules of the same projector, since there is only one module left.

• la figure 1 est une vue schématique du module d'éclairage selon ce mode de réalisation de l'invention ;
• la figure 2 est une vue schématique d'un faisceau d'éclairage produit par le module d'éclairage selon ce mode de réalisation de l'invention ;
• la figure 3 est une représentation schématique d'un premier faisceau lumineux à coupure sensiblement horizontale du faisceau d'éclairage produit par le module d'éclairage selon ce mode de réalisation de l'invention ;
• la figure 4 est une vue schématique d'une partie du module d'éclairage qui est apte à produire le premier faisceau lumineux du faisceau d'éclairage selon ce mode de réalisation de l'invention ;
• la figure 5 est une représentation de la définition d'une coupe verticale du réflecteur selon ce mode de réalisation de l'invention, et
• la figure 6 est une représentation de la définition d'une coupe horizontale du réflecteur selon ce mode de réalisation de l'invention.

Other advantages and characteristics of the invention will appear better on reading the description of a preferred embodiment which will follow, with reference to the figures, produced by way of indicative and nonlimiting example:

• the figure 1 is a schematic view of the lighting module according to this embodiment of the invention;
• the figure 2 is a schematic view of a lighting beam produced by the lighting module according to this embodiment of the invention;
• the figure 3 is a schematic representation of a first light beam with substantially horizontal cut-off of the lighting beam produced by the lighting module according to this embodiment of the invention;
• the figure 4 is a schematic view of a part of the lighting module which is capable of producing the first light beam of the lighting beam according to this embodiment of the invention;
• the figure 5 is a representation of the definition of a vertical section of the reflector according to this embodiment of the invention, and
• the figure 6 is a representation of the definition of a horizontal section of the reflector according to this embodiment of the invention.

With reference to the figure 1 , the lighting module according to this embodiment of the invention comprises first 1 and second 2 sources of light radiation.

These first 1 and second 2 sources of light radiation are capable of emitting laser radiation L1, L2 towards a single conversion device 3 of common wavelength, which is then capable of transmitting this beam to an optical projection system 4.

According to the invention, this first light radiation source 1 comprises: a first laser light source 9 and a reflector 10. According to this preferred variant with a single laser light source 9, it does not include optical focusing elements or other elements between the laser source and the reflector; the first laser light source 9 cooperates directly with the reflector 10. In a variant with several laser sources, not shown, optical elements may be provided to combine the laser rays from the different laser sources. These combination optical elements can for example be based on a mixture of the polarizations of the laser rays and / or a mixture of different wavelengths and / or a juxtaposition of the images of the laser sources.

According to the invention, the second light radiation source 2 comprises a second laser light source 6, a scanning system 7 and optical elements 8 for focusing. These optical focusing elements 8 are located between the second laser light source 6 and the scanning system 7. Thanks to the scanning system, the image from the conversion device is made dynamic and allows adaptive lighting beams to be produced.

The scanning system 7, the reflector 10 and the optical projection system 4 are located on the same side of the conversion device 3, that is to say that the conversion device 3 is used in reflection.

The first 9 and second 6 laser light sources are quasi-point light sources which consist of a laser diode emitting a visible beam whose wavelength is between 400 nanometers and 500 nanometers, and preferably close to 450 or 460 nanometers. These wavelengths correspond to colors ranging from blue to near ultraviolet, the latter color being rather situated towards wavelengths less than 400 nanometers.

This laser diode can be provided with a single cavity and have a power of between approximately 1 and 3.5 watts, preferably 1.6 watts or even 3 watts. This laser diode comprises an output facet whose dimensions can be of the order of 14 μm by 1 μm. It is capable of emitting a beam of elliptical section whose vertical and horizontal light intensity distribution profiles are Gaussian.

• la première source de lumière laser 9 qui peut être positionnée au-dessus et/ou en retrait par rapport au dispositif de conversion 3 de longueur d'onde, et
• le réflecteur 10 qui est positionné devant la première source de lumière laser 9, au-dessus de l'axe optique du système optique de projection 4 entre le dispositif de conversion 3 et le système optique de projection 4.

En effet, comme cela sera détaillé plus loin en référence aux figures 2 et 3, la première source de rayonnement lumineux 1 sert à former la partie inférieure projetée sur la route du faisceau lumineux généré par le module. Cette partie de faisceau est commune aux différents types de faisceaux réglementaires projetés par le module et notamment au faisceau de feu de croisement et de feu de route.Advantageously, the first light radiation source 1 is arranged substantially above the optical axis AO (in dotted lines) of the optical projection system 4, with:

• the first laser light source 9 which can be positioned above and / or set back relative to the wavelength conversion device 3, and
• the reflector 10 which is positioned in front of the first laser light source 9, above the optical axis of the projection optical system 4 between the conversion device 3 and the projection optical system 4.

Indeed, as will be detailed later with reference to figures 2 and 3 , the first light radiation source 1 is used to form the lower part projected on the road of the light beam generated by the module. This part of the beam is common to the different types of regulatory beams projected by the module and in particular to the beam of low beam and high beam.

The first source of light radiation 1 is said to be static because it allows a static image to be formed on the wavelength conversion device 3. However, this first source of light radiation 1 may be quasi-static because it can be moved according to a low angular amplitude in particular and especially at low speed, in particular to ensure a range correction which corresponds to small slow and overall vertical movements to compensate for the vehicle load or its dynamic reaction to braking and acceleration. In the case where the first source of light radiation 1 is static, with a reflector 10 mounted fixedly, it will be possible in conventional manner to carry out a range correction with mechanical means located outside the module and acting on the inclination of the whole module.

According to the invention, the reflector 10 is a static mirror, mounted fixed, or almost static, mounted in rotation about a horizontal axis in order to carry out the vertical range correction movements required. By quasi static is meant in the present application that it is driven by a movement of low amplitude and low speed, less than 15 ° .s ^-1 , preferably less than 10 ° .s ^-1 , advantageously less than 4 ° .s ^-1 .
Compared to the scanning system 7 associated with the second laser light source 6, which comprises at least one micro-mirror movable around a horizontal axis, the speed of oscillation around the horizontal axis of the reflector 10 is at least ten times lower, preferably twenty times lower, preferably at least fifty times lower.

The reflector 10 can be made of metal, for example an aluminum-based alloy or even be of aluminized glass on at least one face.
It is small and can have the following dimensions: a height of about 1.5 to 6 mm, and a width of about 5.5 to 20 mm.

This reflector 10 can be mounted fixed relative to the first laser light source 9. In an alternative embodiment, the reflector is almost static, that is to say that it can also be mounted mobile around a axis and controlled for example by a servomotor or piezoelectric shims to perform the range correction movements, as mentioned above.
This reflector 10 reflects laser radiation L1 coming from this first laser light source 9 towards the wavelength conversion device 3.

The scanning system 7 of the second light radiation source 2 relates, according to a preferred variant, to a micro-mirror which can be square in shape and each side of which can measure approximately 0.8 mm. This micro-mirror is made mobile around two orthogonal axes, for example from a MEMS device (acronym "Micro Electro Mechanical Systems" meaning "Micro Electromechanical Systems"). According to another alternative embodiment, the scanning system can be constituted by the association of two micro-mirrors, each being movable around a single axis, the two axes being orthogonal.

This scanning system 7 reflects laser radiation L2 coming from the second laser light source 6 towards the wavelength conversion device 3. This radiation L2 can then be deflected in two directions by the scanning system 7.

Alternatively, the second laser light source 6 and the scanning system 7 can be included in a MOEMS (acronym for "Micro-Opto-Electro-Mechanical Systems", meaning "microoptoelectromechanical system"). A MOEMS is an optical system comprising, in this case, at least one laser light source and a scanning system 7. MOEMS are compact devices, reliable, simple to use and which allow high precision and great flexibility in redirecting L2 laser radiation to the conversion device 3.

Although in the present embodiment, the second light radiation source 2 comprises a single light source, it can however in an alternative comprise, for example, two laser light sources each emitting radiation towards the same scanning system 7. In alternatively, these two sources can each emit L2 radiation to separate scanning systems.

For example, the lighting module can comprise three scanning systems 7 each equipped with one or more laser light sources. The creation of the light beam in its upper part projected onto the road is thus optimized.
Similarly, in the embodiment described, the first light radiation source 1 comprises a single laser source 9. In the context of the invention, it may include more than one source, for example two laser sources each emitting radiation laser towards the mirror 10, the rays of these two sources possibly being combined before reaching the mirror.

The wavelength conversion device 3 included in the lighting module comprises a substrate forming a reflective support 12 which is covered with a continuous layer 11 of a phosphorescent material.

This support 12 of the conversion device 3 is chosen from materials which are thermally good conductors. Such materials thus allow the support 12 to limit the degradation of the layer 11 of phosphorescent material by restricting the temperature rise of the conversion device 3 and of the layer 11.

The layer 11 of phosphorescent material is capable of re-emitting radiation 16 of white light. Indeed, when the first 1 and second 2 sources of light radiation respectively emit laser radiation L1, L2 monochromatic and coherent towards the conversion device 3, the latter receives this laser radiation L1, L2 and re-emits radiation 16 of white light which has a plurality of lengths of wave belonging to the visible light spectrum and between approximately 400 nanometers and 800 nanometers.

This emission of white light occurs, according to a Lambertian emission diagram, that is to say with uniform luminance in all directions.

The substrate of this conversion device 3 is made for example of metallic material, in particular aluminum. This metallic material constituting the substrate has good characteristics and properties in terms of conduction and thermal resistance. Thus, the substrate advantageously makes it possible to limit the temperature of the layer 11 of phosphorescent material, by promoting the dissipation of heat.

In addition, this substrate can be exposed to laser powers without decomposing, which can be, for example, of the order of 15 watts.

Thus, the conversion device 3 is therefore arranged in the lighting module so as to be able to receive laser radiation L1, L2 originating from the first source of light radiation 1 and from the second source of light radiation 2. This is therefore a conversion device 3 common to all of the laser light sources.

This conversion device 3 is located in the vicinity of the focal plane of the optical projection system 4 which then infinitely forms an image of the layer 11 of phosphorescent material, or more exactly of the points of this layer 11 which emit light in response to the laser excitation resulting from the laser radiation L1, L2 that they receive from the first 1 and second 2 sources of light radiation.

More specifically, the optical projection system 4 forms an illumination beam 15 with the light radiation 16 emitted by the various points of the layer 11 of phosphorescent material illuminated by these laser radiations L1, L2.
The lighting beam 15 emerging from the lighting module is thus a direct function of the light rays emitted by the layer 11 of phosphorescent material, itself a function of the laser radiation L1, L2 absorbed by this layer 11.

It will be noted that the laser radiation L2 coming from the second light radiation source 2 forms an image to be projected by the optical projection system 4, by scanning while taking advantage of the retinal persistence and / or of the metastability of the phosphorescent material.

In addition, the first 1 and second 2 sources of light radiation, the conversion device 3 and the projection optical system 4 are included in this single lighting module which equips a projector.

Therefore, these first 1 and second 2 sources of light radiation share the same conversion device 3 and optical projection system 4. Thus, the size of the lighting module but also that of the projector in which it is mounted, s' finds it greatly reduced.

This lighting module also comprises a control unit 5 which is capable of controlling the first 1 and second 2 sources of light radiation as a function of the desired photometry of the lighting beam 15 produced by this lighting module.
In particular, the control unit 5 controls the scanning system 7 so that the laser radiation L2 successively scans all the zone points of the layer 11 of the phosphorescent material selected by this control unit 5. Thus, it is able to define areas of the layer 11 which should be scanned with laser radiation L2 so as to form an image on this layer 11, such an image consisting of a succession of lines each formed of a succession of more or less bright points.
The control unit 5 also controls the activation and the control of the power of the first 1 and second 2 laser light sources and, if necessary, the modulation of the intensity of the laser radiation L1, L2.
It will be noted that the points of the layer 11 of the phosphorescent material thus illuminated by the laser radiations L1, L2 emit light, with an intensity which is directly a function of the intensity of these laser radiations L1, L2 which illuminate these points, l 'emission taking place according to a Lambertian emission diagram.

According to the invention, this lighting module is capable of emitting a lighting beam 15.
This lighting beam 15 corresponds to the superposition of light beams resulting from the first 1 and second 2 sources of light radiation cooperating with the wavelength conversion device 3 and the optical projection system 4. This superposition can be partial or complete or only concern a fraction of the respective contours of these beams.
This lighting beam 15 can result from the superposition of at least two different light beams, here the first 14 and second 13 light beams, but also from the superposition of more than two beams. Indeed, as we have already mentioned, the second source of light radiation 2 can emit beams produced by several sources of laser light cooperating with one or more scanning systems.

To the figure 2 , is illustrated an example of a light beam 15 produced by the lighting module, known as a passing beam or code as appearing on a flat projection surface.
The planar projection surface is arranged facing the lighting module, perpendicular to the optical axis of the latter.

This low beam type lighting beam 15 results from the superposition of the first light beam 14 and the second light beam 13.

The first light beam 14 is produced by the first light radiation source 1. This first beam 14 represented on the figure 3 , creates a horizontal cut-off line 18. This horizontal cut-off line 18 is a limit lighting line above which it is prohibited to illuminate the road. In countries with right-hand traffic, this cut line is horizontal across the width of the road and on the left side of the road.

To the figure 4 a part of the lighting module illustrated in figure 1 . In this part of the lighting module, the first laser light source 9 is capable of emitting laser radiation L1 which is guided by the reflector 10 towards the upper part 23 of the conversion device 3, in the area located above the horizontal plane of the optical axis AO (shown in dotted lines), in order to concentrate the radiation exclusively under the horizontal cut-off line 18. The conversion device 3 then re-emits radiation 16 of white light towards the optical projection system 4 which forms thus the first light beam 14.
In particular, the reflector 10 is calculated to produce this horizontal cut-off line 18 as well as a controlled energy distribution to produce this first light beam 14.

This first light beam 14 represents a portion of the lighting beam 15 which is common to all the lighting beams regulatory, including crossing or road, likely to be produced by the lighting module. This first light beam 14 generally corresponds to the lower part of the regulatory lighting beams.

These regulatory lighting beams correspond to approved lighting configurations which fulfill the various lighting functions taking into account traffic conditions, such as low beam, city, motorway, gantry or even fog, etc ...

It will be noted that this first light beam 14 fulfills a lighting function at the front of the vehicle on the ground up to approximately 0.5 to 1.5 degrees below the horizon.

The second light beam 13 achieves a non-flat cut, having a horizontal segment 19 which extends into an inclined portion 17 forming an angle of about 10 to 60 degrees upward relative to the horizontal.

The superposition of the second light beam 13 with the first light beam 14 has an overlap area 20 which has a high light intensity.
This overlap area 20 otherwise called "light spot", or "hot spot" is, generally, located in the center of a halo of less intense light. This zone 20 is here positioned substantially at the center of the lighting beam 15 in the axis of said beam 15. In a configuration where the headlamp is of the directional type, that is to say where the upper part of the beam (at above the cut-off line) is offset in the direction of the orientation of the front wheels of the vehicle, this zone 20 will undergo a displacement relative to the axis of the beam, according to the orientation to the left or to the right of the wheels.

Thus, the light beam 15 of the low beam type obtained has a non-flat cut-off line, essentially constituted a low horizontal part 21, followed by a step 17, consisting of an oblique segment at the projection of the optical axis, then a substantially horizontal high part 22. Such a configuration makes it possible not to dazzle the crossed conductors, on the left in the example considered, while ensuring optimal lighting on the right of the road.

The role of such a lighting beam 15 of the code type is to prevent the lighting of the vehicle from dazzling a driver in a vehicle in the opposite direction or the vehicle preceding it.

This example of a beam corresponding to a crossing light beam 15 is applicable to right-hand traffic. This example is of course directly transferable to left-hand traffic conditions.

The lighting beam 15 produced by the lighting module is homogeneous because in this embodiment, the first laser light source 9 has the same characteristics as the second laser light source 6 and the latter both emit radiation L1 , L2 to the same conversion device 3.

The lighting module is of course capable of producing other lighting functions in the same way taking into account traffic conditions and regulations in this area, in particular adaptive road beams or with anti-glare function.

It is well understood that due to the absence of a scanning system at the level of the first light source, and the static or quasi-static nature of the portion of beam generated by the first light source, the potential of the source (s) ( s) laser of the first light source can be optimally exploited and the efficiency of the module is improved.

The reflector 10 has a particular surface 24 which can be determined from the definition of the transformation by reflection on this surface 24 of a Gaussian elliptical beam coming from the first laser light source 9 whose intersection with the conversion device 3 forms an area delimited by a horizontal cut.

As we have seen, this area illuminated by the first laser light source 9 will then, from the conversion device 3, become a quasi-Lambertian white light source which is imaged endlessly by the projection optical system 4.

It will be noted that due to the Gaussian nature of the elliptical beam of the first laser light source 9, it is possible to know in advance the energy distribution resulting from this beam on the conversion device 3.

As illustrated by figures 5 and 6 , sections of the reflector 10 are then determined by a vertical plane and a horizontal plane passing through a source point corresponding to the first laser light source 9.

These vertical and horizontal sections of the reflector 10 are determined by imposing the direction of a ray emitted by the first laser light source 9 and reflected along these sections of the reflector 10 at a current point so that the point d impact of the reflected ray r of vector r on the conversion device 3 describes a horizontal line for the horizontal cut and a vertical line in the case of the vertical cut.

• pour la coupe horizontale $\overrightarrow{\mathrm{i}}=\{\begin{array}{c}\cos \mathrm{\phi }\\ \sin \mathrm{\phi }\\ 0\end{array}$
  
  et $\overrightarrow{\mathrm{p}}=\{\begin{array}{c}\sin \mathrm{\phi }\\ -\cos \mathrm{\phi }\\ 0\end{array}$
  
• pour la coupe verticale : $\overrightarrow{\mathrm{i}}=\{\begin{array}{c}\cos \mathrm{\theta }\\ \sin \mathrm{\theta }\end{array}$
  
  et $\overrightarrow{\mathrm{p}}=\{\begin{array}{c}\sin \mathrm{\theta }\\ -\cos \mathrm{\theta }\end{array}$
  

La position du point courant est définie par M= ρ. i.It is specified that on the figures 5 and 6 , the orthonormal base of the plane is here defined by the reference frame in O, x, y and z, whose center O is placed on the output of the first laser light source 9 and more precisely on the center of the output facet of the diode.
We also have a vector i , representing the direction of the incident ray on the reflector 10 and a vector p perpendicular to i and then we ask for i and p :

• for horizontal cutting $\overrightarrow{\mathrm{i}}=\{\begin{array}{c}\cos \mathrm{\phi }\\ \sin \mathrm{\phi }\\ 0\end{array}$
  
  and $\overrightarrow{\mathrm{p}}=\{\begin{array}{c}\sin \mathrm{\phi }\\ -\cos \mathrm{\phi }\\ 0\end{array}$
  
• for vertical cutting: $\overrightarrow{\mathrm{i}}=\{\begin{array}{c}\cos \mathrm{\theta }\\ \sin \mathrm{\theta }\end{array}$
  
  and $\overrightarrow{\mathrm{p}}=\{\begin{array}{c}\sin \mathrm{\theta }\\ -\cos \mathrm{\theta }\end{array}$
  

The position of the current point is defined by M = ρ. i .

avec :

• pour la coupe horizontale : $\overrightarrow{\mathrm{c}}=\left(\begin{array}{c}\mathrm{D}\\ \mathrm{yi}\left(\mathrm{\phi }\right)\\ \mathrm{Zio}\end{array}\right)$
  
• pour la coupe verticale : $\overrightarrow{\mathrm{c}}=\left(\begin{array}{c}\mathrm{D}\\ \mathrm{Zi}\left(\mathrm{\theta }\right)\end{array}\right)$
  
  D étant la position du système de conversion 3 le long de l'axe optique par rapport à la position de la première source laser 9.

We then impose the position of the impact point C on the conversion device 3 defined by vs as a function of the vertical projected angle vertical or the horizontal projected angle horizontal of the incident ray i on mirror 10, and then, $\overrightarrow{\mathrm{r}}=\frac{\overrightarrow{\mathrm{vs}}-\mathrm{\rho }\overrightarrow{\mathrm{i}}}{\Vert \overrightarrow{\mathrm{vs}}-\mathrm{\rho }\overrightarrow{\mathrm{i}}\Vert },$

with:

• for horizontal cutting: $\overrightarrow{\mathrm{vs}}=\left(\begin{array}{c}\mathrm{D}\\ \mathrm{yi}\left(\mathrm{\phi }\right)\\ \mathrm{Zio}\end{array}\right)$
  
• for vertical cutting: $\overrightarrow{\mathrm{vs}}=\left(\begin{array}{c}\mathrm{D}\\ \mathrm{Zi}\left(\mathrm{\theta }\right)\end{array}\right)$
  
  D being the position of the conversion system 3 along the optical axis relative to the position of the first laser source 9.

S'agissant de la coupe verticale l'équation différentielle en ρ(θ) est : $$\mathrm{\rho }\prime \left(\overrightarrow{\mathrm{r}}.\overrightarrow{\mathrm{i}}-1\right)=\mathrm{\rho }\overrightarrow{\mathrm{r}}.\overrightarrow{\mathrm{p}}$$

Ces équations différentielles peuvent être facilement résolues numériquement à partir de méthodes d'analyse numérique d'approximation de solutions d'équations différentielles comme par exemple la méthode de Runge-Kutta.Thus, the two sections sought are then solutions of differential equations which are written in a canonical form. These differential equations come from the law of reflection expressed in vector form.
Concerning the horizontal section, the differential equation in ρ (ϕ) is: $$\mathrm{\rho }\text{'}=\frac{\mathrm{\rho }\overrightarrow{\mathrm{r}}.\overrightarrow{\mathrm{p}}}{\overrightarrow{\mathrm{r}}.\overrightarrow{\mathrm{i}}-1}$$

Regarding the vertical section the differential equation in ρ (θ) is: $$\mathrm{\rho }\text{'}\left(\overrightarrow{\mathrm{r}}.\overrightarrow{\mathrm{i}}-1\right)=\mathrm{\rho }\overrightarrow{\mathrm{r}}.\overrightarrow{\mathrm{p}}$$

These differential equations can be easily solved numerically from methods of numerical analysis of approximation of solutions of differential equations such as for example the Runge-Kutta method.

• pour assurer l'existence de la coupure horizontale : Z_i(θ) ≥ Z_i0 ;
  Z_i(0) = Z_i0 ; Z_i(θ) doit être monotone et continue pour θ ≥ 0 ; Z_i(θ) doit être monotone et continue pour θ≤0, et
• pour que la surface obtenue corresponde à un réflecteur 10 matériellement réalisable : y_i(ϕ) doit être monotone et croissante.

The two horizontal and vertical sections of the reflector 10 are then obtained by implementing one of these methods, and by imposing the following criteria:

• to ensure the existence of the horizontal cut: Z _i (θ) ≥ Z _i0 ;
  Z _i (0) = Z _i0 ; Z _i (θ) must be monotonic and continuous for θ ≥ 0; Z _i (θ) must be monotonic and continuous for θ≤0, and
• so that the surface obtained corresponds to a reflector 10 materially achievable: y _i (ϕ) must be monotonous and increasing.

Once these two sections of the reflector 10 have been obtained, it is necessary to determine the remainder of the surface 24 of the reflector 10, that is to say the current points of this surface 24 which are not included at the level of these sections of the reflector 10.
To do this, we use a so-called finite difference method which allows point-to-point resolution by optimization under stress.
More precisely, for a current point P _{i, j} if around the position of this point P _{i, j} of the neighboring points P _{i-1, j} and P _{i, j-1} are known, we can approximate the normal NOT at the surface of this point P _{i, j} by vector product with the two neighboring points P _{i-1, j} and P _{i, ji} .

So then: P _{1 + 1, j} P _{1, j} ∧ P _{1, d-1} P _{1, d} = NOT with $${\mathrm{P}}_{\mathrm{i},\mathrm{j}}=\left(\begin{array}{c}\mathrm{x}\\ \mathrm{there}\left(\mathrm{j}\right)\\ \mathrm{z}\left(\mathrm{i}\right)\end{array}\right);{\mathrm{P}}_{\mathrm{i}-1,\mathrm{j}}=\left(\begin{array}{c}\mathrm{x}\\ \mathrm{there}\left(\mathrm{j}\right)\\ \mathrm{z}\left(\mathrm{i}-1\right)\end{array}\right);{\mathrm{P}}_{\mathrm{i},\mathrm{j}-1}=\left(\begin{array}{c}\mathrm{x}\\ \mathrm{there}\left(\mathrm{j}-1\right)\\ \mathrm{z}\left(\mathrm{i}\right)\end{array}\right)$$

We then obtain: $$\overrightarrow{\mathrm{NOT}}=\{\begin{array}{c}-\left(Z\left(i\right)-Z\left(i-1\right)\right)(\mathrm{there}\left(j\right)-\mathrm{there}\left(j-1\right)\\ \left(Z\left(i\right)-Z\left(i-1\right)\right)\left(x-x_{i,j-1}\right)\\ \left(\mathrm{there}\left(j\right)-\mathrm{there}\left(j-1\right)\right)\left(x-x_{i-1,j}\right)\end{array}$$

These two neighboring points P _{i-1, j} and P _{i, j-1} can be points understood on the vertical and horizontal sections and thereafter they can relate to points which will have been solved by this method of finite differences.

It will be noted that through this current point P _{i, j} passes an incident ray emitted by the first laser light source 9, which is defined by a following incident vector: $\frac{\overrightarrow{{\mathrm{op}}_{\mathrm{i},\mathrm{j}}}}{\Vert \overrightarrow{{\mathrm{op}}_{\mathrm{i},\mathrm{j}}}\Vert }$

(loi de la réflexion)We then determine the reflected ray r from the current point P _{i, j} from this normal NOT with: $$\overrightarrow{\mathrm{r}}=\overrightarrow{\mathrm{i}}-2\frac{\overrightarrow{\mathrm{NOT}}.\overrightarrow{\mathrm{i}}}{{\mathrm{NOT}}^2}\overrightarrow{\mathrm{NOT}}=\left(\begin{array}{c}{\mathrm{r}}_{\mathrm{x}}\\ {\mathrm{r}}_{\mathrm{there}}\\ {\mathrm{r}}_{\mathrm{z}}\end{array}\right)$$

(law of reflection)

à partir du point courant P_i,j et du rayon réfléchi r et des coordonnées $\left(\begin{array}{c}\mathrm{D}\\ {\mathrm{y}}_{\mathrm{i}}\left(\mathrm{\phi }\right)\\ {\mathrm{z}}_{\mathrm{i}}\left(\mathrm{\theta }\right)\end{array}\right)$

d'un point d'impact idéal, lesquelles sont comprises sur les coupes verticale et horizontale, soit alors : $${\mathrm{P}}_{\mathrm{i}}={\mathrm{P}}_{\mathrm{i},\mathrm{j}}+\mathrm{\mu }\overrightarrow{\mathrm{r}}$$

avec : ${\mathrm{P}}_{\mathrm{i}}=\left(\begin{array}{c}{\mathrm{x}}_{\mathrm{pi}}\\ {\mathrm{y}}_{\mathrm{pi}}\\ {\mathrm{z}}_{\mathrm{pi}}\end{array}\right),$

${\mathrm{P}}_{\mathrm{i},\mathrm{j}}=\left(\begin{array}{c}\mathrm{x}\\ \mathrm{y}\left(\mathrm{j}\right)\\ \mathrm{z}\left(\mathrm{i}\right)\end{array}\right)$

et µ est la distance P_i,j, P_i.We can therefore define the point of impact P _i , ${\mathrm{P}}_{\mathrm{i}}=\left(\begin{array}{c}{\mathrm{x}}_{\mathrm{pi}}\\ {\mathrm{there}}_{\mathrm{pi}}\\ {\mathrm{z}}_{\mathrm{pi}}\end{array}\right),$

from the current point P _{i, j} and the reflected ray r and coordinates $\left(\begin{array}{c}\mathrm{D}\\ {\mathrm{there}}_{\mathrm{i}}\left(\mathrm{\phi }\right)\\ {\mathrm{z}}_{\mathrm{i}}\left(\mathrm{\theta }\right)\end{array}\right)$

of an ideal point of impact, which are included on the vertical and horizontal sections, that is to say: $${\mathrm{P}}_{\mathrm{i}}={\mathrm{P}}_{\mathrm{i},\mathrm{j}}+\mathrm{\mu }\overrightarrow{\mathrm{r}}$$

with: ${\mathrm{P}}_{\mathrm{i}}=\left(\begin{array}{c}{\mathrm{x}}_{\mathrm{pi}}\\ {\mathrm{there}}_{\mathrm{pi}}\\ {\mathrm{z}}_{\mathrm{pi}}\end{array}\right),$

${\mathrm{P}}_{\mathrm{i},\mathrm{j}}=\left(\begin{array}{c}\mathrm{x}\\ \mathrm{there}\left(\mathrm{j}\right)\\ \mathrm{z}\left(\mathrm{i}\right)\end{array}\right)$

and µ is the distance P _{i, j} , P _i .

sont alors égales à : $${\mathrm{x}}_{\mathrm{pi}}=\mathrm{x}+{\mathrm{\mu r}}_{\mathrm{x}}=\mathrm{D};$$

$${\mathrm{y}}_{\mathrm{pi}}=\mathrm{y}\left(\mathrm{j}\right)+\mathrm{\mu }{\mathrm{r}}_{\mathrm{y}}=\mathrm{y}\left(\mathrm{j}\right)+\left(\mathrm{D}-\mathrm{x}\right)\frac{r_y}{r_x}\mathrm{car}\mathrm{\mu }=\frac{D-x}{r_x}$$

$${\mathrm{Z}}_{\mathrm{pi}}=\mathrm{Z}\left(\mathrm{i}\right)+\mathrm{\mu }{\mathrm{r}}_{\mathrm{z}}=\mathrm{Z}\left(\mathrm{i}\right)+\left(\mathrm{D}-\mathrm{x}\right)\frac{r_z}{r_x}\mathrm{car}\mathrm{\mu }=\frac{D-x}{r_x}$$

The coordinates of the point of impact ${\mathrm{P}}_{\mathrm{i}}=\left(\begin{array}{c}{\mathrm{x}}_{\mathrm{pi}}\\ {\mathrm{there}}_{\mathrm{pi}}\\ {\mathrm{z}}_{\mathrm{pi}}\end{array}\right)$

are then equal to: $${\mathrm{x}}_{\mathrm{pi}}=\mathrm{x}+{\mathrm{ÁR}}_{\mathrm{x}}=\mathrm{D};$$

$${\mathrm{there}}_{\mathrm{pi}}=\mathrm{there}\left(\mathrm{j}\right)+\mathrm{\mu }{\mathrm{r}}_{\mathrm{there}}=\mathrm{there}\left(\mathrm{j}\right)+\left(\mathrm{D}-\mathrm{x}\right)\frac{r_{\mathrm{there}}}{r_x}\mathrm{because}\mathrm{\mu }=\frac{D-x}{r_x}$$

$${\mathrm{Z}}_{\mathrm{pi}}=\mathrm{Z}\left(\mathrm{i}\right)+\mathrm{\mu }{\mathrm{r}}_{\mathrm{z}}=\mathrm{Z}\left(\mathrm{i}\right)+\left(\mathrm{D}-\mathrm{x}\right)\frac{r_z}{r_x}\mathrm{because}\mathrm{\mu }=\frac{D-x}{r_x}$$

considéré dont les coordonnées sont sur des coupes verticale et horizontale.Thereafter, minimization under constraints is then carried out to determine the position x of the current point P _{i, j} . It is a question here of minimizing the distance from the point of impact P _i on the device 3 for converting the reflected ray. r , compared to an ideal point of impact $\left(\begin{array}{c}\mathrm{D}\\ {\mathrm{there}}_{\mathrm{i}}\left(\mathrm{\phi }\right)\\ {\mathrm{z}}_{\mathrm{i}}\left(\mathrm{\theta }\right)\end{array}\right)$

considered whose coordinates are on vertical and horizontal sections.

Is $${\left({\mathrm{there}}_{\mathit{pi}}-{\mathrm{there}}_i\left(\mathrm{\phi }\right)\right)}^2+{\left(Z_{\mathit{pi}}-{\mathrm{<figure-callout\; id="2"\; label="Z\; i\; \theta "\; filenames="imgf0001.png"\; state="\{\{state\}\}">Z\; </figure-callout>}}_i\left(\mathrm{\theta }\right)\left(\mathrm{}\right)\right)}^2$$

• la coordonnée latérale y_pi du point d'impact P_i ne doit pas être de signe opposé à la coordonnée latérale y(j) du point courant P_i,j pour ne pas changer de côté par rapport au plan vertical contenant l'axe optique et éviter ainsi de générer une ligne brillante au milieu du premier faisceau lumineux 14. On pose alors que : y_pi y(j) ≥ 0 ;
• la coordonnée verticale Z_pi du point d'impact P_i doit être supérieure ou égale à Z_i0 pour ne pas dépasser la ligne horizontale inférieure. On a Z_pi ≥ Z_i0.

This minimization must be carried out with the following constraints:

• the lateral coordinate y _pi of the point of impact P _i must not be of opposite sign to the lateral coordinate y (j) of the current point P _{i, j} so as not to change sides with respect to the vertical plane containing the optical axis and thus avoid generating a bright line in the middle of the first light beam 14. We then state that: y _pi y (j) ≥ 0;
• the vertical coordinate Z _pi of the point of impact P _i must be greater than or equal to Z _i0 so as not to exceed the lower horizontal line. We have Z _pi ≥ Z _i0 .

This minimization can be carried out using an "inner point" type algorithm, the operation of which is described in particular in the scientific publication entitled " An interior algorithm for nonlinear optimization that combines line search and trust region steps ", and whose authors are RA Waltz, JL Morales, J. Nocedal, and D. Orban. This publication is taken from the book" Mathematical Programming ", Vol 107, No. 3, pages 391-408, published in 2006 .

This minimization is then subsequently carried out by this algorithm for all the impact points capable of being defined on the surface 24 of this reflector 10 by the first laser light source in order to produce the first light beam 14.

Thus, by defining the transformation by reflection on the reflector of the Gaussian elliptical beam coming from the first laser light source 9 towards the conversion device 3, it is then possible to determine the particular surface 24 of this reflector 10.

It is clear that by choosing the functions y _i (ϕ) and Z _i (θ) adequately, the distribution of the light flux in the projection on the road is determined according to the specifications of the desired photometry.

The method for determining the surface of the mirror 10 which has just been exposed in the case of a single laser source can be transposed to a configuration in which the laser sources of the first light source 1 are combined. In this case, the center of the virtual laser source resulting from the combination of the rays will be taken as center O of the frame of reference.

Before approaching the other possible configurations, it will be recalled that the laser rays have a transverse section of the Gaussian elliptical type and therefore comprise a large and a small axis.

In the case where the rays of the laser sources are not combined, the laser sources are then placed so that either the plane of the large axes or that of the small axes are merged.
If the rays do not overlap (for a width of 1 / e ² ) then each laser beam is reflected on a dedicated portion of the mirror, calculated as detailed above (each source is considered individually).
If there is a superposition of laser rays, then the mirror 10 will be of the cylindrical type, its cross section being calculated as detailed above for one of the laser sources and the laser sources of the first light source 1 are aligned along a line parallel to l axis of the mirror cylinder.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field of claims below. The scanning variations of the conversion system to obtain an advanced lighting function can then be generated by using a hiding device, for example rotary, which will create cut lines.

Claims (10)

1. Lighting module for a motor vehicle headlamp comprising first (1) and second (2) light radiation sources capable of emitting laser radiation (L1, L2) to a wavelength conversion device (3) which is capable of re-emitting light radiation (16) to an optical projection system (4) in order to produce an illumination beam (15), the module comprising a single wavelength conversion device (3) which is common to the laser radiation (L1, L2), characterised in that the first light radiation source (1) comprises at least a first laser light source (9) cooperating with a single reflector (10) which is a mirror mounted fixedly or mounted in rotation about a horizontal axis and driven with a movement of small amplitude and low speed, that is less than 15°.s^-1, preferably less than 10°.s^-1, preferably less than 4°.s^-1, and the second light source (2) has at least one second laser light source (6) which cooperates with at least one scanning system (7) having at least one micromirror which is movable about a horizontal axis.
2. Illumination module according to claim 1, characterised in that the first light radiation source (1) is arranged above an optical axis of the projection optical system (4).
3. An illumination module according to any one of claims 1 to 2, characterized in that the first laser light source (9) is positioned above or recessed from the wavelength conversion device (3).
4. An illumination module according to any one of claims 1 to 3, characterized in that the reflector (10) is positioned in front of the first laser light source (9) above an optical axis of the projection optical system (4) between the wavelength conversion device (3) and the projection optical system (4).
5. Lighting module according to any one of claims 1 to 4, characterized in that the reflector (10) is a mirror made of metal, in particular an aluminium-based alloy.
6. An illumination module according to any one of claims 1 to 5, characterized in that the first laser light source (9) is capable of emitting laser radiation (L1) to the reflector (10) which is capable of directing it towards an upper part (23) of the surface of the wavelength conversion device (3).
7. An illumination module according to any one of claims 1 to 6, characterised in that the second light radiation source (2), the reflector (10) and the projection optical system (4) are arranged on the same side of the wavelength conversion device (3).
8. Lighting module according to any one of claims 1 to 7, characterized in that the first (9) and second (6) laser light sources are laser diodes, in particular laser diodes having the same characteristics.
9. Motor vehicle headlamp comprising a light module according to any of the preceding claims, in particular a single light module according to any of the preceding claims
10. Method of producing an illumination beam (15) for a motor vehicle headlamp comprising the following steps :

    - formation of a first light beam (14) producing a first part which is the lower part projected onto the road of said lighting beam (15) by means of a first light radiation source (1) comprising at least one first laser light source (9) emitting laser radiation (L1) directed by a single reflector (10), which is a mirror mounted fixedly or mounted in rotation about a horizontal axis and driven with a movement of small amplitude and low speed, that is less than 15°.s^-1, preferably less than 10°.s^-1, preferably less than 4°.s^-1, to a single wavelength conversion device (3), the wavelength conversion device (3) re-emitting light radiation to a projection optical system (4),

    - formation of a second light beam (13)) producing a second part of said illumination beam (15) by means of a second light radiation source (2) comprising at least one second laser light source (6) which cooperates with at least one scanning system (7) comprising at least one micromirror movable about a horizontal axis, the second laser light source (6) emitting laser radiation (L2) directed by the scanning system (7) to said single wavelength conversion device (3), the wavelength conversion device (3) re-emitting light radiation to the projection optical system (4), and

    - at least partial superimposition of the first (14) and second (13) light beams.

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