EP2730838A1 - Lighting module for a vehicle headlamp comprising several light sources - Google Patents

Abstract

The lighting module (2) for a motor vehicle headlamp, comprises:
light sources arranged successively, in particular along a curve (4),
a cylindrical reflector (8) and
- A lens (10) adapted to receive light from each source from the reflector.

The reflector is arranged to form, from the light emitted by one of the light sources, a light spot, the reflector having, in a plane perpendicular to the generatrices of the cylinder, a section shaped so as to modify the ratio of the dimensions of the light spot with respect to the ratio of the dimensions of the light source and so as to modify the light distribution in the light spot with respect to the light distribution of the light source.

The lens has at least two focal points, or even a focal area, and is arranged in such a way that the image formed by the lens of an object placed at one of these focal points is clear.

Description

The invention relates to lighting devices such as projectors for motor vehicles.

It is known to provide on a motor vehicle lighting functions in high beam and low beam. The first provides illumination the entire width of the road in front of the vehicle. The second provides illumination of the lane in which the vehicle is located and a reduced illumination of the lane located next to it and in which vehicles are likely to come in the opposite direction. In this way, the occupants of the latter are not dazzled. However, the dipped beam function in its most usual form does not illuminate far enough the side of the road beyond this adjacent lane. This is a source of danger. For example, if a pedestrian on the roadside is about to cross the road, it will not be visible early enough by the driver.

To remedy this, an adaptive fire function has been proposed which makes it possible to illuminate at a great distance and selectively certain parts of the scene in front of the vehicle and in particular the aisle located beyond the adjacent lane. For this purpose, an observation device analyzes the scene and selects the areas to be illuminated.

For this, it is known in particular to cut this scene fictitiously into several vertical rectangular strips that are selectively illuminated according to the parts of the scene that one wishes to illuminate. (The same type of operation can be implemented with a matrix arrangement, ie in columns and in lines, of the different areas of the scene to be illuminated selectively.) It is also desirable to further illuminate the parts. lower bands than their upper part.

A projector for implementing this operation is presented in the document EP-2 278 217 . It comprises several contiguous modules intended to form the respective bands. Each module comprises a light source, a reflector and a lens for making one of the strips. The reflector has a shape such that it spreads the light of the source in the vertical direction and the lower part of the strip is brighter than its upper part.

But this projector is cumbersome because you have to juxtapose as many modules as desired bands.

An object of the invention is to overcome this drawback and therefore reduce the volume device for selectively illuminating different areas of the scene visible in front of the vehicle.

• des sources de lumière disposées successivement, notamment le long d'une courbe,
• un réflecteur cylindrique et
• une lentille apte à recevoir de la lumière de chaque source provenant du réflecteur,

le module étant tel que:

• le réflecteur est agencé de manière à former, à partir de la lumière émise par une des sources de lumière, une tache lumineuse, le réflecteur présentant, dans un plan perpendiculaire aux génératrices du cylindre, une section conformée de façon à modifier le rapport des dimensions de la tache lumineuse par rapport au rapport des dimensions de la source de lumière et de façon à modifier la répartition lumineuse dans la tache lumineuse par rapport à la répartition lumineuse de la source de lumière, et
• la lentille présente au moins deux foyers, voire une zone focale, et est agencée de manière à ce que l'image formée par la lentille d'un objet placé à l'un de ces foyers soit nette.

For this purpose, the invention provides a lighting module for a motor vehicle headlamp, which comprises:

• light sources arranged successively, in particular along a curve,
• a cylindrical reflector and
• a lens adapted to receive light from each source from the reflector,

the module being such that:

• the reflector is arranged to form, from the light emitted by one of the light sources, a light spot, the reflector having, in a plane perpendicular to the generatrices of the cylinder, a section shaped so as to modify the ratio of the dimensions of the light spot with respect to the ratio of the dimensions of the light source and so as to modify the light distribution in the light spot with respect to the light distribution of the light source, and
• the lens has at least two focal points, or even a focal zone, and is arranged in such a way that the image formed by the lens of an object placed at one of these foci is clear.

Thus, the sources are associated with the same reflector and the same lens. The volume of the device is therefore considerably reduced.

The light source is defined here as the light-emitting surface of a member such as an LED.

Regarding the sharpness, the lens is arranged so that the image formed by the lens of an object placed at one of its homes has a sharp outline throughout its length. A net outline is defined as follows:

Let I (h, v) be an intensity as a function of two angles h and v (for example equal to log (illumination on a screen at 25 m).

The contrast is then equal to ∥grad (I) ∥.

The outline is said net if at each point the contrast is greater than a predetermined threshold (for example 0.13 according to the European standard).

It can be provided in particular that the reflector has, in a plane perpendicular to the generatrices of the cylinder, a section shaped to increase a dimension of an image of each source by the reflector and so that a mean value of a luminous flux in an upper half of the image of each source projected by the lens is less than an average value flow in a lower half of the image.

Thus, the light power supplied is greater in the lower part of the spots than in the upper part.

Preferably, the reflector has a curved section having a point of inflection, preferably single.

Such a shape promotes obtaining a good distribution of light in each of the spots in the vertical direction.

Preferably, the lens is arranged such that a sharpness of an overall image of the sources provided by the lens is maximum at at least two predetermined points of that image compared with other areas of the image.

It is therefore an optically optimized lens to take into account the plurality of sources and thus obtain a good sharpness in the vertical edges of the spots, so that the illumination produced has no discontinuity or hot spot corresponding to a power bright too important. The device thus produces a comfortable lighting for the driver of the vehicle and allows him to apprehend as best as possible the scene in front of the vehicle.

In one embodiment, the points are located on the edges of the images of two sources, these images being immediately adjacent to an image of the same source, these edges being located on the image side of the latter.

In another embodiment, the dots are located on edges of the images of two sources, these images being immediately adjacent to each other, the edge of each image being located on a side opposite the other image .

Each of these two embodiments represents a good compromise for optimizing the lens and obtaining satisfactory illumination.

Advantageously, a face of the lens has corrugations.

This feature makes it possible to slightly blur the top horizontal edge of the stains to avoid having a cut too bright light intensity between the stain and the environment, usually night, which improves the comfort and enjoyment of the driver.

Advantageously, the face of the lens having the corrugations is an exit face of the source light.

It can be expected that each source has a square shape in a plane perpendicular to a main direction of emission of light by the source.

Such sources, especially when they consist of light-emitting diodes, have a lower cost than rectangular sources, which makes their use advantageous. In addition, the module according to the invention makes it possible to obtain a large spreading in the vertical direction from from square sources.

• les sources de lumière sont disposées de sorte qu'il existe une droite passant par l'ensemble des sources, notamment par l'un des bords de chaque source ;
• les sources de lumières sont disposées de manière à ce qu'il existe une courbe passant par un des sommets du contour de chaque source de lumière ;
• les sources de lumières sont disposées de manière à ce qu'il existe une courbe passant par le centre de chaque source de lumière ;
• la courbe est dépourvue de point d'inflexion ;
• les contours des sources sont contenus dans un même plan ;
• chaque source présente deux bords opposés, et les bords opposés de toutes les sources sont parallèles entre eux ; et
• les bords sont parallèles à l'axe optique.

The module may furthermore exhibit at least any of the following characteristics:

• the light sources are arranged so that there is a straight line passing through all the sources, in particular by one of the edges of each source;
• the light sources are arranged in such a way that there is a curve passing through one of the vertices of the contour of each light source;
• the light sources are arranged in such a way that there is a curve passing through the center of each light source;
• the curve is devoid of point of inflection;
• the contours of the sources are contained in the same plane;
• each source has two opposite edges, and the opposite edges of all the sources are parallel to each other; and
• the edges are parallel to the optical axis.

Advantageously, the module is arranged so that the sources are controllable individually from each other.

Advantageously, the module comprises a screen forming an obstacle to the direct transmission of light from the sources to the lens.

Otherwise, this light transmitted directly to the lens forms parasitic rays in the bands.

It is also provided according to the invention a motor vehicle headlight which comprises at least one module according to the invention and preferably comprises several.

This projector can also constitute a signaling device.

Another object according to the invention is a motor vehicle comprising at least one module or a lighting device according to the invention.

• la figure 1 est une vue en perspective schématique d'un module selon l'invention ;
• la figure 2 est un schéma illustrant le trajet de la lumière dans le module de la figure 1 ;
• la figure 3 illustre la forme de la section du réflecteur du module de la figure 1 ;
• les figures 4 et 5 sont des schémas représentant certaines grandeurs utilisées pour le calcul du réflecteur du module de la figure 1 ;
• la figure 6 est une courbe illustrant l'évolution de l'éclairement normalisé renvoyé par chaque point du réflecteur en fonction de la coordonnée de ce point le long d'un axe parallèle à l'axe du véhicule ;
• la figure 7 est une courbe représentant le décalage vertical différentiel de la position d'un point du réflecteur par rapport à un réflecteur à section rectiligne en fonction de l'éclairement renvoyé par ce point ;
• les figures 8 et 9 sont deux vues des images des sources produites par le réflecteur et utilisées pour l'optimisation optique de la lentille dans le module de la figure 1 dans deux modes de réalisation respectifs; et
• la figure 10 montre les bandes lumineuses produites par le module de la figure 1 telle qu'elles apparaissent sur un écran disposé devant le véhicule sur sa route.

We will now present an embodiment of the invention with reference to the accompanying drawings in which:

• the figure 1 is a schematic perspective view of a module according to the invention;
• the figure 2 is a diagram illustrating the path of light in the module of the figure 1 ;
• the figure 3 illustrates the shape of the reflector section of the module of the figure 1 ;
• the Figures 4 and 5 are diagrams representing certain quantities used for the calculation of the reflector of the module of the figure 1 ;
• the figure 6 is a curve illustrating the evolution of the normalized illuminance reflected by each point of the reflector according to the coordinate of this point on along an axis parallel to the axis of the vehicle;
• the figure 7 is a curve representing the differential vertical offset of the position of a point of the reflector relative to a reflector with a straight section as a function of the illumination reflected by this point;
• the Figures 8 and 9 are two views of the images of the sources produced by the reflector and used for optical optimization of the lens in the module of the figure 1 in two respective embodiments; and
• the figure 10 shows the light bands produced by the module of the figure 1 as they appear on a screen placed in front of the vehicle on the road.

We have illustrated Figures 1 to 3 a lighting module 2 for a motor vehicle headlight according to the invention.

Module 2 comprises light sources 4, a cover or screen 6, a mirror or reflector 8 and a lens 10.

An orthogonal reference mark XYZ illustrated in FIG. figure 1 and in which the horizontal axes X and Y are respectively perpendicular and parallel to the direction of travel of the vehicle and the Z axis is vertical.

The light sources 4 are made in this case in the form of light-emitting diodes. They are arranged to produce upward-directed illumination with their vertical optical axis. They present here a square shape in view in a plane perpendicular to this optical axis. Each source has in plan a surface equal for example to 1 mm ² . The sources are aligned in a direction parallel to the X axis. The sources are for example carried by a circuit board 12 common to all sources. The number of sources is any. It is greater than or equal to three and the highest possible, each source producing one of the bands forming the lighting.

It is therefore observed that the light sources are arranged so that there is a straight line passing through all the sources, in particular by one of the edges of each source. The contours of the sources are contained in the same plane. Each source has two opposite edges, and the opposite edges of all the sources are parallel to each other. The edges are parallel to the optical axis.

The screen 6 is arranged to prevent light sources from arriving directly on the lens 10.

The latter has a rear face 14 and a front face 16 thus referred to by reference to the path of the source light and the direction of travel of the vehicle. As illustrated in figure 2 at least part of the light of each source 4 is reflected by the reflector 8 towards the face 14 and then leaves the lens by the face 16 in the form of parallel rays between them and the Y axis.

We illustrated at the figure 10 the overall image produced by the module on a vertical screen which would be disposed in a plane parallel to the X and Z axes across the road 22 in front of the vehicle. This overall image is divided into as many vertical rectangular strips 24 as there are sources 4. The height of each band is greater than its width. The strips are juxtaposed by their vertical edges. Some of the bands extend in front of the vehicle to illuminate the entire road, in this case the two tracks of the latter and other bands, beyond the previous ones in the direction of the X axis, so as to illuminate the aisles of the road.

In the present example, the strips 24 are identical to each other. However one can predict that these bands differ in their width and / or in their length. Similarly, here, the upper and lower horizontal edges of the strips are respectively in coincidence. But this is not obligatory. In addition, a single horizontal row of strips is provided here. But it can be expected that the module produces at least two horizontal rows of strips extending one above the other.

The face of the reflector 8 exposed to the light of the sources has a cylindrical shape, the generatrices of the cylinder being parallel to the axis X. It has a section in a plane parallel to the axes Y and Z, shown in FIG. figure 3 , on which rely the generators.

Since the lens 10 receives light from all sources 4, it is optically optimized so that the bands 24 forming the source images have the sharpest vertical edges possible. We will see later how this optimization is carried out.

In addition, knowing that the lens is common to all sources and that the latter are preferably small, making the reflector 8 in the form of an anamorphic does not achieve simple results. This is why we choose here to calculate the shape of the reflector so that it provides satisfactory or optimal results. In particular, the shape of its section illustrates the figure 3 is distinct from a line segment and a conic.

This form is calculated to fulfill several functions.

The first is to spread vertically in the vertical direction of the image of each source 4 so that the reflector produces a rectangular image 24 of a square source.

The second function is to distribute the light power from the source so as to provide more light power in the lower part of the band 24 at the top. More specifically, it is sought to ensure that the light power in the band per unit area is even lower than is located at a great distance from the lower edge of the strip.

To calculate the shape of the section of the reflector, we first seek to determine the evolution of the normalized illuminance reflected by each point of the reflector according to the coordinate of this point along an axis parallel to the axis of the vehicle ;

• I est l'intensité rayonnée par la source dans la direction du point du réflecteur considéré, et
• δΩ est l'angle solide infinitésimal sous lequel est vue la source depuis le point considéré.

Starting from a straight section parallel to the X axis and oriented at 45 ° with respect to the Y and Z axes as shown in FIG. figure 3 . We consider a single source 4 located at the right of this section. The Y axis passes through the plane of the source and the Z axis passes through its front end which thus forms the origin O of the marker. With reference to the figure 4 at each point of the section, a flux δΦ = I.δΩ is calculated where:

• I is the intensity radiated by the source in the direction of the point of the reflector considered, and
• δΩ is the infinitesimal solid angle under which the source is viewed from the considered point.

The values of δΦ are reduced between 0 and 1 by an affine transformation, from the weakest to the strongest.

To perform this calculation, the following method is implemented.

• E_r est l'éclairement produit par la source au point (0, y_r, z_r) du réflecteur. Il s'agit du flux par élément de surface du réflecteur ;
• E_s est l'émittance de la source qui est supposée lambertienne ;
• α est l'angle formé par rapport à l'axe Z par une droite passant par un point courant de la source et le point considéré du réflecteur ;
• θ est l'angle formé par cette droite avec la normale au réflecteur en ce point ;
• r est la distance du point courant de la source au point considéré sur le réflecteur ;
• h désigne la largeur de la source suivant l'axe X ;
• L_s est la longueur de la source suivant l'axe Y ;
• x_s et y_s sont les coordonnées d'un point courant de la source ; et
• dz(E_r) désigne le décalage qu'on souhaite donner suivant la direction de l'axe Z à l'image de la source réfléchie par le point du réflecteur.

With reference to the figure 5 :

• E _r is the illumination produced by the source at the point (0, y _r , z _r ) of the reflector. This is the flux per surface element of the reflector;
• E _s is the emittance of the source which is supposed to be Lambertian;
• α is the angle formed with respect to the Z axis by a straight line passing through a current point of the source and the considered point of the reflector;
• θ is the angle formed by this line with the normal to the reflector at this point;
• r is the distance from the current point of the source to the point considered on the reflector;
• h denotes the width of the source along the X axis;
• L _s is the length of the source along the Y axis;
• x _s and y _s are the coordinates of a current point of the source; and
• dz (E _r ) denotes the offset that we wish to give in the direction of the Z axis in the image of the source reflected by the point of the reflector.

l'intégrale étant prise sur la source $$\mathrm{soit}{\mathrm{E}}_{\mathrm{r}}=\left({\mathrm{E}}_{\mathrm{s}}/\mathrm{\pi }\right)\iint \left(\mathrm{cos\alpha cos\theta }/{\mathrm{r}}^{\mathrm{2}}\right){\mathrm{dx}}_{\mathrm{s}}{\mathrm{dy}}_{\mathrm{s}}$$

l'intégrale étant prise sur $\left[-\frac{{\mathrm{h}}_s}{2};\frac{{\mathrm{h}}_s}{2}\right]x\left[-{\mathrm{L}}_s;0\right]\mathrm{.}$

We can write: $${\mathrm{E}}_{\mathrm{r}}=\iint \left({\mathrm{E}}_{\mathrm{s}}\mathrm{cos\alpha cos\theta }/{\mathrm{<figure-callout\; id="2"\; label="\pi r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\pi r</figure-callout>}}^{\mathrm{2}}\right)\mathrm{dS}$$

the integral being taken on the source $$\mathrm{is}{\mathrm{E}}_{\mathrm{r}}=\left({\mathrm{E}}_{\mathrm{s}}/\mathrm{\pi }\right)\iint \left(\mathrm{cos\alpha cos\theta }/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\mathrm{2}}\right){\mathrm{dx}}_{\mathrm{s}}{\mathrm{dy}}_{\mathrm{s}}$$

the integral being taken on $\left[-\frac{{\mathrm{<figure-callout\; id="2"\; label="h\; s"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">h\; </figure-callout>}}_s}{2};\frac{{\mathrm{<figure-callout\; id="2"\; label="h\; s"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">h\; </figure-callout>}}_s}{2}\right]x\left[-{\mathrm{The}}_s;0\right]\mathrm{.}$

$${\mathrm{r}}^{\mathrm{2}}={\left({\mathrm{y}}_{\mathrm{z}}-{\mathrm{y}}_{\mathrm{r}}\right)}^{\mathrm{2}}+{\mathrm{x}}_{\mathrm{z}}^{\mathrm{2}}+{\mathrm{z}}_{\mathrm{r}}^{\mathrm{2}}$$

où n_y et n_z sont les coordonnées non nulles du vecteur unitaire normal au réflecteur au point considéré.Otherwise, $$\begin{array}{r}\cos =\left(\left({\mathrm{there}}_{\mathrm{s}}-{\mathrm{there}}_{\mathrm{r}}\right){\mathrm{not}}_{\mathrm{there}}-{\mathrm{z}}_{\mathrm{r}}{\mathrm{not}}_{\mathrm{z}}\right)/\sqrt{{\left({\mathrm{there}}_{\mathrm{s}}-{\mathrm{there}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}\right)}^{\mathrm{2}}+{\mathrm{x}}_{\mathrm{s}}^{\mathrm{2}}+{\mathrm{<figure-callout\; id="2"\; label="z\; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">z\; </figure-callout>}}_{\mathrm{r}}^{\mathrm{}}}\\ \cos ={\mathrm{z}}_{\mathrm{r}}/\sqrt{{\left({\mathrm{there}}_{\mathrm{s}}-{\mathrm{there}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}\right)}^{\mathrm{2}}+{\mathrm{x}}_{\mathrm{s}}^{\mathrm{2}}+{\mathrm{z}}_{\mathrm{r}}^{\mathrm{2}}}\end{array}$$

$${\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\mathrm{2}}={\left({\mathrm{there}}_{\mathrm{z}}-{\mathrm{there}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}\right)}^{\mathrm{2}}+{\mathrm{x}}_{\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">z</figure-callout>}}^{\mathrm{2}}+{\mathrm{<figure-callout\; id="2"\; label="z\; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">z\; </figure-callout>}}_{\mathrm{r}}^{\mathrm{}}$$

where n _y and n _z are the non-zero coordinates of the unit vector normal to the reflector at the considered point.

It follows that: $${\mathrm{E}}_{\mathrm{r}}=\left({\mathrm{E}}_{\mathrm{s}}{\mathrm{z}}_{\mathrm{r}}/\mathrm{\pi }\right)\iint \left(\frac{\left({\mathrm{there}}_{\mathrm{s}}-{\mathrm{there}}_{\mathrm{r}}\right){\mathrm{not}}_{\mathrm{there}}-{\mathrm{z}}_{\mathrm{r}}{\mathrm{not}}_{\mathrm{z}}}{{\left({\mathrm{there}}_{\mathrm{s}}-{\mathrm{there}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}\right)}^{\mathrm{2}}+{\mathrm{x}}_{\mathrm{s}}^{\mathrm{2}}+{\mathrm{<figure-callout\; id="2"\; label="z\; r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">z\; </figure-callout>}}_{\mathrm{r}}^{\mathrm{}}}\right){\mathrm{dx}}_{\mathrm{s}}{\mathrm{dy}}_{\mathrm{s}}$$

For the planar reflector, the virtual images created at any point of the reflector are of the same size and E _r is the emittance of the virtual image of the point (0, y _r , z _r ).

alors $$n_{\mathrm{y}}={\mathrm{f}}_{\mathrm{z}}^{\mathrm{ʹ}}/\sqrt{{{\mathrm{f}}_{\mathrm{y}}^{\mathrm{ʹ}}}^{\mathrm{2}}+{{\mathrm{f}}_{\mathrm{z}}^{\mathrm{ʹ}}}^{\mathrm{2}}}\mathrm{et}{\mathrm{n}}_{\mathrm{z}}=-{\mathrm{f}}_{\mathrm{y}}^{\mathrm{ʹ}}/\sqrt{{{\mathrm{f}}_{\mathrm{y}}^{\mathrm{ʹ}}}^{\mathrm{2}}+{{\mathrm{f}}_{\mathrm{z}}^{\mathrm{ʹ}}}^{\mathrm{2}}}$$

et dans le cas du réflecteur plan à 45° : $$f_y=u+y_0\mathrm{et}{f}_z=u+z_0$$

y₀ et z₀ étant des constantes et les coordonnées d'un point du réflecteur.It is noted that: $${\mathrm{if\; there}}_{\mathrm{r}}={\mathrm{f}}_{\mathrm{there}}\left(\mathrm{u}\right){\mathrm{and\; z}}_{\mathrm{r}}={\mathrm{f}}_{\mathrm{z}}\left(\mathrm{u}\right)$$

so $${\mathrm{not}}_{\mathrm{there}}={\mathrm{f}}_{\mathrm{z}}^{\mathrm{\text{'}}}/\sqrt{{{\mathrm{f}}_{\mathrm{there}}^{\mathrm{\text{'}}}}^{\mathrm{2}}+{{\mathrm{f}}_{\mathrm{z}}^{\mathrm{\text{'}}}}^{\mathrm{2}}}\mathrm{and}{\mathrm{not}}_{\mathrm{z}}=-{\mathrm{f}}_{\mathrm{there}}^{\mathrm{\text{'}}}/\sqrt{{{\mathrm{f}}_{\mathrm{there}}^{\mathrm{\text{'}}}}^{\mathrm{2}}+{{\mathrm{f}}_{\mathrm{z}}^{\mathrm{\text{'}}}}^{\mathrm{2}}}$$

and in the case of the 45 ° plane reflector: $$f_{\mathrm{there}}=u+{\mathrm{there}}_0\mathrm{and}{f}_z=u+{\mathrm{<figure-callout\; id="0"\; label="z"\; filenames="imgf0002.png"\; state="\{\{state\}\}">z</figure-callout>}}_0$$

y ₀ and z ₀ being constants and the coordinates of a point of the reflector.

The symmetry of the origin of the reference with respect to the 45 ° plane passing through the point (y ₀ , z ₀ ) is at the point (y ₀ - z ₀ , y ₀ + z ₀ ). The top of the virtual images (thus the bottom of the projected images) passes by this point. dz (E _r ) is thus measured along the -Z axis from this point.

Let f _y ( u ) = u and consider a point (x _r , y _r ) of the reflector.

So we have ${\mathrm{not}}_{\mathrm{there}}=f_z^{\text{'}}/\sqrt{1+f_z^{{\text{'}}^2}}\mathrm{and}{\mathrm{not}}_z=-1/\sqrt{1+f_z^{{\text{'}}^2}}$

un rayon incident au point considéré provenant de O : $$\overrightarrow{i}=\frac{1}{\sqrt{u^2+f_z^2}}\times \left(u{f}_z\right)$$

Is

an incident ray at the point considered from O: $$\overrightarrow{i}=\frac{1}{\sqrt{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">u</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="f\; z"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_z^{}}}\times \left(u{f}_z\right)$$

$$\begin{array}{c}\overrightarrow{r}=\frac{1}{\sqrt{u^2+f_z^2}}\cdot \left(\left(u{f}_z\right)-2.\frac{u{f}_z^{ʹ}-f_z}{1+{f_z^{ʹ}}^2}\mathrm{.}\left(f_z^{ʹ},-1\right)\right)\\ \overrightarrow{r}=\left(r_y\left(u{f}_z{f}_z^{ʹ}\right),r_z\left(u{f}_z{f}_z^{ʹ}\right)\right)\end{array}$$

The direction of the reflected ray is: $$\overrightarrow{r}=\overrightarrow{i}-2\left(\overrightarrow{i}\mathrm{.}\overrightarrow{\mathrm{not}}\right)\overrightarrow{\mathrm{not}}$$

$$\begin{array}{c}\overrightarrow{r}=\frac{1}{\sqrt{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">u</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="f\; z"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_z^{}}}\cdot \left(\left(u{f}_z\right)-2.\frac{u{f}_z^{\text{'}}-{\mathrm{<figure-callout\; id="1"\; label="f\; z"\; filenames="imgf0002.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_z}{1+{f_z^{\text{'}}}^2}\mathrm{.}\left(f_z^{\text{'}},-1\right)\right)\\ \overrightarrow{r}=\left(r_{\mathrm{there}}\left(u{f}_z{f}_z^{\text{'}}\right),r_z\left(u{f}_z{f}_z^{\text{'}}\right)\right)\end{array}$$

et tel que : $${\mathrm{\lambda }}_{\mathrm{r}}-{\mathrm{\lambda r}}_{\mathrm{y}}=\mathrm{u}-{\mathrm{\lambda r}}_{\mathrm{y}}={\mathrm{y}}_{\mathrm{0}}-{\mathrm{z}}_{\mathrm{0}}$$

si bien que : $$\mathrm{\lambda }=\frac{{\mathrm{y}}_{\mathrm{0}}-{\mathrm{z}}_{\mathrm{0}}-\mathrm{u}}{{\mathrm{r}}_{\mathrm{y}}}$$

The virtual ray meets the plane of the virtual images of the reflector at 45 ° at a point I such that: $$I=\left({\mathrm{there}}_r{z}_r\right)-\lambda \overrightarrow{\mathrm{r}}$$

and such as: $${\mathrm{\lambda }}_{\mathrm{r}}-{\mathrm{\lambda r}}_{\mathrm{there}}=\mathrm{u}-{\mathrm{\lambda r}}_{\mathrm{there}}={\mathrm{there}}_{\mathrm{0}}-{\mathrm{<figure-callout\; id="0"\; label="z"\; filenames="imgf0002.png"\; state="\{\{state\}\}">z</figure-callout>}}_{\mathrm{0}}$$

so that: $$\mathrm{\lambda }=\frac{{\mathrm{there}}_{\mathrm{0}}-{\mathrm{z}}_{\mathrm{0}}-\mathrm{u}}{{\mathrm{r}}_{\mathrm{there}}}$$

And the reflector moves the image as desired if: $${\mathrm{z}}_{\mathrm{r}}-{\mathrm{\lambda r}}_{\mathrm{z}}={\mathrm{f}}_{\mathrm{z}}\frac{{\mathrm{there}}_{\mathrm{0}}-{\mathrm{z}}_{\mathrm{0}}-\mathrm{u}}{{\mathrm{r}}_{\mathrm{there}}}\cdot {\mathrm{r}}_{\mathrm{z}}={\mathrm{z}}_{\mathrm{0}}-{\mathrm{there}}_{\mathrm{0}}-{\mathrm{d}}_{\mathrm{z}}\left({\mathrm{E}}_{\mathrm{r}}\left(\mathrm{u}{\mathrm{f}}_{\mathrm{z}}\right)\right)$$

It is an equation in u, f _z and f ' _z . This differential equation in f _z is numerically soluble with the initial condition f _z (y ₀ ) = z ₀ and as parameters y ₀ , z ₀ and dzE _r .

We have thus illustrated figure 6 the evolution of the illumination E _r produced by the source as a function of the coordinate along the Y axis of the considered point of the reflector.

In the case in point, in the band corresponding to the source, it is sought to move the images of the source produced by the different parts of the reflector according to the light flux that they convey. Specifically, we seek to increase the images carrying a low light intensity and down images carrying a high intensity. For this, in this case, it is arbitrarily determined which offset dz in the vertical direction give the source images produced by the reflector as a function of the value of illumination. We illustrated at the figure 7 the evolution that one chooses here to apply for this shift dz according to the value of the illumination E _r .

Then, at each point of the reflector, the normal orientation of the reflector is calculated to produce the desired offset. Once this orientation has been determined for all the points of the reflector, the position of each point is determined knowing that we start from the lower edge of the reflector which is common to the plane reflector oriented at 45 °. We can build the reflector step by step. This orientation calculation and this construction can be done without difficulty by a computer program.

The section obtained in the form illustrated in figure 3 . It is fully curved while having a point of inflection I located in the lower quarter of the reflector. Below this point, the center of curvature of the reflector is in front of it, contrary to what happens above this point.

This produces a vertical spreading of the beam of the source without anamorphosis. In addition, an average value of a luminous flux in an upper half of the image 24 of each source projected by the lens is less than an average value of the flux in a lower half of the image.

Moreover, the lens 10 is optimized in its two diopters to minimize annoying aberrations. For this, we take into account the two or three LEDs closest to the optical axis of the lens. We have illustrated Figures 8 and 9 two modes of implementation of this optimization. These figures show the images 26 of the sources as reflected by the reflector. These are aligned rectangular strips whose largest dimension is measured in the vertical direction. The tapes are not joined.

On the figure 8 , in one embodiment particularly applicable when the sources are odd, it is arranged that the optical axis 28 of the lens, which is parallel to the Y axis, passes through the vertical plane of symmetry of the image 26a from the source located in the center of the alignment. The images 26b and 26c of the two adjacent sources are closest to the central image 26a. The lens is optimized so that the following two edges benefit from the maximum sharpness: the vertical edge 30 of the image 26c which is the closest to the image 26a and the vertical edge 30 of the image 26b which is the closest from picture 26a. In this case, the lens is optimized so as to favor the sharpness of the vertical edges closest to the optical axis of the images of the lateral images 26b and 26c. The images of the edges of the central image 26a are somewhat fuzzy as are the external lateral edges of the images of the images 26b and 26c. We can then obtain three reasonably sharp bands but having a sharpness lower than the case of the figure 9 explained below. The present mode applies when it is desired to have a strong overlap of the beams of the left and right headlights of the vehicle when they are designed in accordance with the invention.

On the figure 9 it is another embodiment. The optical axis 28 of the lens passes through the vertical plane of symmetry of the interval 32 located in the center of the alignment, between two of the images 26. It is therefore two images adjacent to each other . The lens is optimized so that the edge 35 of each of these two images 26 which is furthest from the gap has the maximum sharpness. This case is applicable when the beam of the module extends weakly towards the interior of the vehicle. In this case, the images of the edges of the images closest to the optical axis are a little fuzzy. This case makes it possible to obtain two very sharp bands and applies when it is desired to have a low overlap of the beams of the left and right headlights of the vehicle when they are designed in accordance with the invention.

The module according to the invention makes it possible in particular to obtain strips whose vertical edges are suitably sharp. The module according to the invention makes it possible to produce a beam that does not have black stripes on the image 20 between the strips 24. This avoids a combing effect that is detrimental to the appearance.

In the present case, it is anticipated that the exit face 16 of the lens has corrugations having a depth of a few microns. These corrugations have the effect of slightly blurring the small upper and lower sides of each strip so that the light transition between the strip and its environment at its vertical ends is carried out as gently as possible.

The sources are addressable so as to make it possible to control, by means of appropriate control means of the module, the production of each band of light individually from each other.

For example, the greatest total length measured along the Y axis between the lens and the reflector may be about 40 mm.

This module can also provide the function of high beams and / or low beam, possibly alone or in addition to one or more other devices.

A projector comprising such a module may also be equipped with one or more traffic lights.

Of course, we can bring to the invention many changes without departing from the scope thereof.

In particular, it is possible to transfer some of the images of the source having a low light intensity near the lower end of the bands, in particular to ensure a smooth transition with a complementary beam superimposed on the lower part of the bands.

Claims (18)

Lighting module (2) for a motor vehicle headlamp, which comprises: light sources arranged successively, in particular along a curve (4), a cylindrical reflector (8) and a lens (10) able to receive light from each source coming from the reflector, the module being characterized in that : the reflector is arranged so as to form, from the light emitted by one of the light sources, a light spot, the reflector having, in a plane perpendicular to the generatrices of the cylinder, a section shaped so as to modify the ratio of the dimensions of the light spot in relation to the ratio of the dimensions of the light source and so as to modify the light distribution in the light spot with respect to the light distribution of the light source, and the lens has at least two foci, or even a focal zone, and is arranged in such a way that the image formed by the lens of an object placed at one of these foci is clear. Module according to the preceding claim wherein the reflector (8) has a curved section having a point of inflection, preferably single. Module according to at least one of the preceding claims, in which the lens (10) is arranged so that a sharpness of a global image (20) of the sources provided by the lens is maximum at at least two predetermined points of this lens. image by comparison with other areas of the image. Module according to the preceding claim wherein the points are located on the edges of the images of two sources, these images being immediately adjacent to an image of the same source, these edges being located on the image side of the latter. Module according to claim 3 wherein the points are located on the edges of the images of two sources, these images being immediately adjacent to each other, the edge of each image being located on one side opposite to the other image . Module according to at least one of the preceding claims, in which a face (16) of the lens has corrugations. Module according to the preceding claim wherein the face of the lens having the corrugations is an output face (16) of the source light. Module according to at least one of the preceding claims, in which each source (4) has a square shape in a plane perpendicular to a main direction of emission of light by the source. Module according to at least one of the preceding claims, in which the light sources (4) are arranged so that there is a straight line passing through all the sources, in particular one of the edges of each source. Module according to at least one of the preceding claims, in which the light sources (4) are arranged in such a way that there is a curve passing through one of the vertices of the contour of each light source. Module according to at least one of the preceding claims, in which the light sources (4) are arranged in such a way that there is a curve passing through the center of each light source. Module according to the preceding claim wherein the curve has no inflection point. Module according to at least one of the preceding claims, in which the contours of the sources (4) are contained in the same plane. Module according to at least one of the preceding claims wherein each source (4) has two opposite edges, and the opposite edges of all the sources are parallel to each other. Module according to the preceding claim wherein the edges are parallel to the optical axis. Module according to at least one of the preceding claims arranged so that the sources (4) are individually controllable from each other. Module according to at least one of the preceding claims which comprises a screen (6) obstructing the direct transmission of light from the sources to the lens. Motor vehicle headlamp which comprises at least one module (2) according to at least one of the preceding claims and preferably comprises several.

Images