EP1528312B1 - Lighting module for vehicle headlamp - Google Patents

Description

The present invention relates to a lighting module for a vehicle headlight providing a cut-off type lighting beam particularly suitable for use with light-emitting diodes.

By cut-off lighting beam is meant a lighting beam which has a directional or cutoff limit above which the emitted light intensity is low.

The dipped beam and fog lamp functions are examples of cut-off light beams in accordance with current European legislation.

Generally, in an elliptical projector, the cut is made by means of a cover, which is formed of a vertical plate of suitable profile, which is interposed axially between the elliptical reflector and the convergent lens, and which is arranged in the vicinity of second focus of the reflector.

The cache makes it possible to mask the light rays coming from the light source and reflected by the reflector towards the lower part of the focal plane of the convergent lens, and which would, in the absence of a cover, be emitted by the projector above the cut.

However, such a solution presents certain difficulties.

Thus, a disadvantage of this type of projector is that a significant portion of the light flux emitted by the source is dissipated in the rear face of the cache.

Another solution consists in producing a lighting module using a light source and a Fresnel optic or a reflector of the complex surface type. To create a cut, it is necessary to align the edges of the images of the light source on the measurement screen used to validate the regulation light beam.

This solution also poses certain problems.

Thus, when the light source is a diode, it is very difficult to achieve a clean cut. Indeed, the image of the virtual source corresponding to the diode is generally round is diffuse and it is much more complicated to make a clean cut by aligning the corresponding images of round shapes.

This difficulty can be overcome by using a diaphragm with the diode, but then a significant amount of the light energy produced by the diode is lost.

In addition, the emission indicators of the most efficient known diodes are complex and the production of a homogeneous beam is very difficult to obtain from the direct images of the diode.

• un réflecteur elliptique qui délimite un volume de réflexion et qui comporte une surface elliptique de réflexion;
• au moins une source lumineuse qui est agencée au voisinage d'un premier foyer du réflecteur, et
• une lentille convergente dont le plan focal est agencé au voisinage du second foyer du réflecteur.

Document is known EP-A-1,357,334 a lighting module producing a cut-off lighting beam, comprising, arranged from rear to front along a horizontal optical axis:

• an elliptical reflector which delimits a reflection volume and which has an elliptical reflection surface;
• at least one light source which is arranged in the vicinity of a first focus of the reflector, and
• a convergent lens whose focal plane is arranged in the vicinity of the second focus of the reflector.

In this module, the reflector comprises a horizontal flat surface, whose upper surface is reflecting, which defines vertically downwardly the reflection volume, and which has a cutoff edge which is arranged in the vicinity of the second focus of the reflector.

The convergent lens is a thick optical system, relatively difficult to manufacture, and of a significant weight.

The present invention aims at providing a lighting module for a vehicle headlamp producing a lighting beam of the cut-off type making it possible to achieve a clean cut, in particular by using a diode as a light source, as well as a beam of light. homogeneous lighting while offering less loss of luminous flux by avoiding the use of a cache.

• un premier réflecteur comportant une surface de réflexion des rayons lumineux, dont la coupe dans un plan est une ellipse
• au moins une source lumineuse agencée au voisinage du premier foyer dudit premier réflecteur,
• caractérisé en ce que ledit module comporte :
  • un deuxième réflecteur produisant une première partie du faisceau à coupure et ayant un axe optique passant par le second foyer dudit premier réflecteur,
  • un troisième réflecteur produisant une deuxième partie du faisceau à coupure et ayant un axe optique passant par le second foyer dudit premier réflecteur,
  • un quatrième réflecteur, dit plieuse, agencé entre ledit deuxième réflecteur et ledit troisième réflecteur et comportant :
  • un bord, dit bord de coupure, agencé au voisinage dudit second foyer dudit premier réflecteur de manière à former la coupure dans le faisceau d'éclairage,
  • une face supérieure réfléchissante incluant lesdits axes optiques respectifs desdits deuxième et troisième réflecteur.

The present invention proposes for this purpose a lighting module for a vehicle headlight producing a lighting beam of the cut-off type comprising:

• a first reflector comprising a reflection surface of the light rays, the section of which in a plane is an ellipse
• at least one light source arranged in the vicinity of the first focus of said first reflector,
• characterized in that said module comprises:
  • a second reflector producing a first portion of the cut-off beam and having an optical axis passing through the second focus of said first reflector,
  • a third reflector producing a second portion of the cut-off beam and having an optical axis passing through the second focus of said first reflector,
  • a fourth reflector, called a bender, arranged between said second reflector and said third reflector and comprising:
  • an edge, said cutting edge, arranged in the vicinity of said second focus of said first reflector so as to form the cut in the lighting beam,
  • a reflective upper face including said respective optical axes of said second and third reflectors.

Thanks to the invention, the majority of the luminous flux emitted by the source is used in the light beam produced by the module.

In addition, the lighting module according to the invention makes it possible to achieve a clean cut, in particular with a diode, because it projects the image of the cutting edge at the front. The shape of the cut-off in the lighting beam is thus determined by the profile of the cut-off edge.

Another advantage of the module according to the invention is that it exploits a property of the elliptical lighting modules which is to "mix" the images of the light source at the second focus of the first reflector, which improves the homogeneity of the beam. product lighting.

In addition, such a module has improved optical performance compared to a system using a lens; there are indeed fewer losses due to the non-unit reflection coefficient of the reflective surfaces of the second and third reflectors than by glass reflections in the lens.

Finally, depending on the configuration of the invention, the first reflector and its light source may be concealed behind one of said second or third reflectors so that the user looking at the output beam does not see the first reflector. Such a solution allows for example to overcome the use of a mask to hide the first reflector and its light source.

Advantageously, the optical axes of said second and third reflectors coincide.

Advantageously, said first reflector is arranged behind said second reflector so that said first reflector is concealed by said second reflector

Advantageously, said second reflector and said third reflector have a focus arranged in the vicinity of said second focus of said first reflector.

According to an advantageous embodiment, said second reflector and / or said third reflector comprise a reflection surface of the light rays whose section in a plane is a parabola.

According to another advantageous embodiment, said second reflector and / or said third reflector are a type of reflector with a complex surface for reflecting light rays.

In a particularly advantageous manner, said light source is a light-emitting diode.

Particularly advantageously, said cutting edge is a beveled edge defining an oblique surface, said oblique surface being determined so that said cutting edge does not intercept the rays reflected by said first reflector and passing beyond said second focus.

Advantageously, said second focus of said first reflector is in the center of the intersection line portion between said oblique surface and said reflective upper face of said folder.

Advantageously, according to a first solution, said first and third reflectors are made in one piece and / or said second and fourth reflectors are made in one piece.

Advantageously, according to a second solution, said second, third and fourth reflectors are made in one piece.

According to a very advantageous embodiment, the lighting module comprises a fifth reflector receiving directly light rays from said first light source, the reflecting surface of said fifth reflector being such that it produces a third portion of the cut-off beam.

Advantageously, according to a first solution, said first, third and fifth reflectors are made in one piece.

Advantageously, according to a second solution, said first and fifth reflectors are made in one piece.

• un réflecteur dit sans coupure produisant ledit deuxième faisceau d'éclairage sans coupure et ayant un axe optique passant par le second foyer dudit premier réflecteur et perpendiculaire à l'axe optique dudit premier réflecteur,
• une deuxième source lumineuse agencée au voisinage du foyer dudit réflecteur sans coupure.

Advantageously, the lighting module produces a second unlighted lighting beam and comprises:

• an uninterrupted reflector producing said second unbreakable illumination beam and having an optical axis passing through the second focus of said first reflector and perpendicular to the optical axis of said first reflector,
• a second light source arranged in the vicinity of the focus of said unbroken reflector.

According to this latter embodiment, the reflecting surface of said unbroken reflector may be a substantially paraboloidal surface to which a reduction factor is applied in a direction perpendicular to the optical axis of said first reflector and to the optical axis of said sixth reflector.

According to this last embodiment, said unbroken reflector may be a reflector of complex surface reflection type of light rays.

• un cinquième réflecteur symétrique dudit premier réflecteur par rapport au plan de la face supérieure réfléchissante de ladite plieuse,
• une deuxième source lumineuse agencée au voisinage du premier foyer dudit cinquième réflecteur.

According to another embodiment, the lighting module comprises:

• a fifth reflector symmetrical of said first reflector with respect to the plane of the reflective upper face of said folder,
• a second light source arranged in the vicinity of the first focus of said fifth reflector.

Advantageously, according to this last embodiment, said cutoff edge is a beveled edge defining an oblique surface, said oblique surface being determined so that said cutting edge does not intercept the rays reflected by said first reflector and passing beyond said second focus, said oblique surface being reflective and receiving a portion of the light rays from said fifth reflector and said module comprises a sixth reflector receiving light rays from said oblique surface, said sixth reflector having a substantially paraboloidal surface of reflection of light rays with a fireplace arranged in the vicinity of said second focus of said first reflector.

Advantageously, according to this last embodiment, said module comprises a seventh reflector directly receiving the light rays coming from said second light source and having a substantially paraboloidal surface for reflecting light rays.

Particularly advantageously, said folder comprises a corrective surface of the field curvature located along said cutting edge and in the continuity of said upper face of said folder so that no ray coming from said first reflector and returned to said third reflector does not exceed said cut.

Said corrective surface may be a surface which absorbs light or a reflective surface inclined at a given angle with respect to the plane of said reflective upper face of said folder so that the rays coming from said first reflector and which would have been returned to above the cut in the absence of said corrective surface are entirely reflected in a direction opposite to the direction of said first cut-off lighting beam.

In a variant, the first reflector consists of an ellipso-parabolic surface. In this case, it is advantageous to provide that the second reflector and / or the third reflector is a parabolic cylinder.

• le premier réflecteur collecteur comporte une surface de réflexion des rayons lumineux dont la coupe dans un plan est une ellipse,
• au moins une première source lumineuse est agencée au voisinage du premier foyer dudit réflecteur,

ledit module comportant :

• un réflecteur de sortie produisant un faisceau à coupure et ayant un axe optique passant par le second foyer dudit premier réflecteur et perpendiculaire à l'axe optique dudit premier réflecteur,
• un réflecteur dit plieuse, agencé entre ledit premier réflecteur collecteur et ledit réflecteur de sortie comportant :
  • un bord, dit bord de coupure, agencé au voisinage dudit second foyer dudit premier réflecteur de manière à former la coupure dans le faisceau d'éclairage,
  • une face supérieure réfléchissante incluant ledit axe optique du premier réflecteur collecteur.
• la source lumineuse émettant la majorité de son énergie lumineuse dans la direction opposée à celle de l'émission du faisceau d'éclairage du type à coupure.

According to another variant,

• the first collector reflector comprises a reflection surface of light rays whose section in a plane is an ellipse,
• at least one first light source is arranged in the vicinity of the first focus of said reflector,

said module comprising:

• an output reflector producing a cut-off beam and having an optical axis passing through the second focus of said first reflector and perpendicular to the optical axis of said first reflector,
• a so-called bending reflector arranged between said first collector reflector and said output reflector comprising:
  • an edge, said cutting edge, arranged in the vicinity of said second focus of said first reflector so as to form the cut in the lighting beam,
  • a reflective upper face including said optical axis of the first collector reflector.
• the light source emitting the majority of its light energy in the opposite direction to the emission of the cut-off type lighting beam.

It is then advantageous to provide that the first collector reflector consists of an ellipso-parabolic surface, and / or that the third output reflector is a parabolic cylinder.

Other features and advantages of the present invention will appear in the following description of embodiments of the invention, given for illustrative and not limiting.

• La figure 1 représente schématiquement une vue de coté d'un module d'éclairement selon un premier mode de réalisation de l'invention illustrant le trajet des rayons lumineux,
• La figure 2 représente schématiquement une vue de coté d'un module d'éclairement selon un deuxième mode de réalisation de l'invention et illustrant le trajet de certains rayons lumineux,
• La figure 3 représente schématiquement une vue de coté d'un module d'éclairement selon un troisième mode de réalisation de l'invention,
• La figure 4 représente schématiquement une vue de coté d'un module d'éclairement selon un quatrième mode de réalisation de l'invention,
• La figure 5 représente une courbe d'isophote d'un module d'éclairement tel que représenté en figure 1 avec un bord de coupure sans correction de courbure de champ,
• La figure 6 représente une surface correctrice de courbure de champ utilisé dans un module tel que représenté en figure 1,
• La figure 7 représente une courbe d'isophote d'un module d'éclairement tel que représenté en figure 1 avec un bord de coupure corrigé avec la surface représentée en figure 6,
• La figure 8 représente une courbe d'isophote d'une variante de module d'éclairement tel que représenté en figure 1 avec des surfaces réfléchissantes modifiées.
• La figure 9 représente une variante du mode de réalisation de la figure 1.

In the following figures:

• The figure 1 schematically represents a side view of an illumination module according to a first embodiment of the invention illustrating the path of the light rays,
• The figure 2 schematically represents a side view of an illumination module according to a second embodiment of the invention and illustrating the path of certain light rays,
• The figure 3 schematically represents a side view of an illumination module according to a third embodiment of the invention,
• The figure 4 schematically represents a side view of an illumination module according to a fourth embodiment of the invention,
• The figure 5 represents an isophote curve of an illuminance module as shown in FIG. figure 1 with a cutoff edge without field curvature correction,
• The figure 6 represents a correction surface of field curvature used in a module as shown in FIG. figure 1 ,
• The figure 7 represents an isophote curve of an illuminance module as shown in FIG. figure 1 with a cut edge corrected with the surface represented in figure 6 ,
• The figure 8 represents an isophote curve of a variant of illumination module as represented in FIG. figure 1 with modified reflective surfaces.
• The figure 9 represents a variant of the embodiment of the figure 1 .

In all the figures, the common elements bear the same reference numbers.

The figure 1 schematically represents a side view of a vehicle headlamp lighting module 1 according to a first embodiment of the invention.

• un premier réflecteur 2,
• un deuxième réflecteur 3,
• un troisième réflecteur 4,
• un quatrième réflecteur 5,
• une source lumineuse 6.

Module 1 comprises:

• a first reflector 2,
• a second reflector 3,
• a third reflector 4,
• a fourth reflector 5,
• a light source 6.

• deux foyers F1 et F2,
• un axe optique A2,
• une surface réfléchissante 7 sensiblement elliptique.

The first reflector 2 is an elliptical reflector having:

• two foci F1 and F2,
• an optical axis A2,
• a substantially elliptical reflecting surface 7.

The substantially elliptical reflecting surface 7 is made in the form of an angular sector substantially of revolution and which extends in the half-space above an axial plane perpendicular to the plane of the sheet and containing the optical axis A2. As a first approximation, the surface 7 is a half-ellipsoid.

It may however be noted that the surface 7 may not be perfectly elliptical and have several specific profiles intended to optimize the light distribution in the light beam produced by the module 1. This implies that the first reflector 2 is not perfectly revolution .

The light source 6 is arranged substantially at the first focus F1 of the first reflector 2.

Advantageously, the light source 6 is a light-emitting diode which emits the majority of its light energy towards the reflecting inner surface of the substantially elliptical surface 7.

This diode 6 is for example a diode made of gallium nitride GaN with a phosphor for emitting white light.

• un foyer sensiblement confondu avec le second foyer F2 du premier réflecteur 2,
• un axe optique A1,
• une surface réfléchissante 8.

The second reflector 3 comprises:

• a focus substantially coincident with the second focus F2 of the first reflector 2,
• an optical axis A1,
• a reflective surface 8.

The optical axis A1 is substantially parallel to the longitudinal axis of a vehicle not shown and equipped with the lighting module 1 and forms an angle equal to 90 ° with the optical axis A2.

The reflective surface 8 is of substantially paraboloidal shape, the axis of the parabola being the optical axis A1.

• un foyer sensiblement confondu avec le second foyer F2 du premier réflecteur 2,
• un axe optique A1 identique à celui du deuxième réflecteur 3,
• une surface réfléchissante 9.

The third reflector 4 comprises:

• a focus substantially coincident with the second focus F2 of the first reflector 2,
• an optical axis A1 identical to that of the second reflector 3,
• a reflecting surface 9.

Let Y be the same direction and in the same direction as the optical axis A2, a direction Z identical and opposite to the optical axis A1 and a direction X so that the XYZ center mark F2 forms a direct reference.

The third reflector 4 is then substantially symmetrical to the second reflector 3 with respect to the plane (F2, X, Z). Note, however, that the symmetrical nature of the second and third reflectors 3 and 4 is optional.

The fourth reflector 5, also called a bender, is located between the second reflector 3 and the third reflector 4 and comprises at least one reflective upper face and a front end edge 11, said cutting edge.

The cutting edge 11 is arranged in the vicinity of the second focus F2 of the first reflector 2.

The operating principle of module 1 is as follows:

We will consider for this reason three light rays R1, R2 and R3 coming from the light source 6.

Since the light source 6 is arranged at the first focus F1 of the first reflector 2, the majority of the rays emitted by the source 6, after being reflected on the inner face 7, is returned to the second focus F2 or in the vicinity of the second focus F2. -this. This is the case of the radius R1 which passes along the cutting edge 11. R1 is then reflected on the surface 9 of the third reflector 4 in a direction substantially parallel to the optical axis A1 of the third reflector 4. Note here that the cutting edge 11 has a bevel 12 defining an oblique surface. This oblique surface 12 is determined so that the cutting edge 11 is not likely to intercept rays reflected by the first reflector 2 and passing beyond the second focus F2.

Other rays may, after being reflected on the inner face 7, reflect on the surface 10 of the folder 5; this is the case of R2. R2 will then reflect again on the paraboloidal surface 8 of the second reflector 3 and this reflection will be downwards in the plane of the figure 1 . The radius R2 is thus emitted under the cut-off in the lighting beam. Without the reflection of R2 on the surface 10, the radius R2 would have reflected on the surface 9 of the third reflector 4 and would have been unacceptable (because above the cut).

Other radii, of the R3 type, can pass beyond the edge 11. In such a case, the radius R3 is then reflected on the surface 9 of the third reflector 4 and is also reemitted under the cut in the beam of lighting.

The reflective surface 10 allows to "fold" the images of the light source 6 which are reflected by the elliptical surface 7 of the first reflector 2 to the second focus F2.

The "fold" formed by this "folding" of images contributes to forming a clean cut in the illumination beam reflected by the second and third reflectors 3 and 4.

The first reflector 2 is located behind the second reflector 3 so that, when looking at the front module (facing the optical axis A1), we do not see the first reflector 2 and the light source 6; these are hidden by the second reflector and it is useless to provide a cache.

Note that we considered that the second and third reflectors are perfectly symmetrical, so with the same optical axis A1; they may not be symmetrical and have different optical axes, the only condition being that their optical axes intersect at the second focus F2 of the first reflector and belong to the same plane (F2, X, Z).

Note also that the rear face 13 of the folder 5 may be reflective for construction reasons but this reflecting part will not be used.

The figure 2 schematically represents a side view of a vehicle projector lighting module 100 according to a second embodiment of the invention.

This module 100 is identical to module 1 of the figure 1 with the difference that it further comprises a fifth reflector 14.

This fifth reflector has a reflecting surface 15 which receives light rays directly from the light source 6 and produces a beam of light rays below the horizontal cut. If the light source 6 was punctual and without surrounding optical device, the reflective surface 15 would be a paraboloidal surface with a focus located at the second focus F2 of the first reflector.

In practice, the light source 6 such as a light-emitting diode is not a point source and comprises a not shown chip of square or rectangular surface surrounded by a spherical plastic half-lens not shown and centered on the center of the chip. Therefore, the non-punctualities of the source and the lens must be taken into consideration for the construction of the reflecting surface 15.

Without a lens but with only a non-point source, a complex surface can be used to make the reflective surface.

When the source is not only non-point but also has a spherical lens, one solution is to construct the reflective surface from a source considered as point and from the point 17 of the square of the chip closest to the fifth reflector 14.

The reflecting surface 15 is then constructed so that the radius R5 from point 17 is parallel to the optical axis A1. The construction can be done by considering the spherical wave surface from point 17 which is then transformed into a non-spherical wave surface via its passage through the plastic half-lens. This non-spherical wave surface can be determined by the laws of Descartes. The reflecting surface 15 is constructed so as to obtain a plane wave surface corresponding to a plane parallel to the optical axis A1 after reflection on the reflecting surface 15 of the non-spherical wave surface previously determined. Its equation is obtained by writing the constancy of the optical path along a ray coming from point 17 to a plane perpendicular to the optical axis (this plane can be chosen arbitrarily but must be identical for all the radii considered).

Once the reflective surface is determined, since the point 17 is the closest point to this surface 15, the other radii such as the radius R6 coming from the point 18 farther away from the surface 15 will give rise to a radius at below the cut after reflection on the surface 15.

This fifth reflector 14 makes it possible to significantly increase the intensity of the cut-off beam by recovering the light that would, in the absence of this fifth reflector 14, be lost towards the rear of the module 100.

Note that the first, third and fifth reflectors respectively 2, 4 and 14 can be made in one piece with a simple mold without drawer in a standard plastic material of the type PPS (Polysulfide of phenylene). It is the same for the second reflector 3 and the folder 5. In both cases, the reflective coating has to be deposited only on one side since there are reflecting optical surfaces on one side only .

Note also that the fifth reflector can occupy a reduced space under the first reflector 2 and thus leave a free area 16 between said first and fifth reflectors in which an optical device can be inserted for the performance of an additional function such that the production of an unbroken beam such as daytime running lights or daytime running light (DRL).

The figure 3 schematically represents a side view of a vehicle projector lighting module 101 according to a third embodiment of the invention.

• un réflecteur 18 dit sans coupure,
• une deuxième source de lumière 20.

This module 101 is identical to module 1 of the figure 1 with the difference that it furthermore comprises:

• a reflector 18 said without cut,
• a second light source 20.

This unbroken reflector 18 has a substantially paraboloidal inner reflecting surface 19 with an optical axis coinciding with the optical axis A1 of the second and third reflectors 3 and 4 and a focus F3.

This focus F3 is positioned positively along the axis F2-Z and the light source 20 is arranged in the vicinity of said focus F3.

If the reflective surface 19 of the unbroken reflector 18 was a true parabola, it would produce a substantially circular unbroken output beam. However, the regulatory bodies require that the uninterrupted functions of the road or DRL type have a beam that is about twice as wide as it is high, ie the beam must spread twice as much along X than according to Y.

Therefore, if it is desired to add a second function of the uninterruptible type to the module 101 which complies with the regulatory standards, it is necessary to adapt the reflecting surface 19.

A first solution consists in applying a reduction factor adapted along X to paraboloid 19. This transformation can be carried out in a known manner by optical optimization software of the CODE V type.

Another solution consists in producing a complex surface for the reflecting surface 19 by adding streaks on the surface as described in the documents FR2760068 and FR2760067 .

The figure 4 schematically represents a side view of a vehicle projector lighting module 102 according to a fourth embodiment of the invention.

• un cinquième réflecteur 21,
• une deuxième source de lumière 27,
• un sixième réflecteur 23,
• un septième réflecteur 25.

This module 102 is identical to module 1 of the figure 1 with the difference that it furthermore comprises:

• a fifth reflector 21,
• a second light source 27,
• a sixth reflector 23,
• a seventh reflector 25.

The fifth reflector 21 is substantially symmetrical to the first reflector 2 with respect to the plane (F2, X, Z). Therefore, the first focus F4 of this fifth reflector 21 is symmetrical to the focus F1 of the first reflector 2 relative to the second focus F2 of the first reflector 2 and the second focus of the fifth reflector is coincident with the second reflector F2 of the first reflector 2 .

The second light source is substantially arranged in the vicinity of the first focus F4 of the fifth reflector

The reflecting surface 22 of the fifth reflector 21 is therefore substantially elliptical with an optical axis A3 directed in the direction opposite to the optical axis A2.

The bevel 12 of the folder is made reflective so that it can reflect a portion of the rays reflected on the reflecting surface 22 of the fifth reflector 21.

The sixth reflector 23 receives the light rays coming from the reflective bevel 12, said sixth reflector 23 having a surface substantially paraboloidal reflection of light rays with a focus disposed in the vicinity of the second focus F2 of the first reflector 2.

The seventh reflector 25 has a substantially paraboloidal reflecting surface 26 which produces a beam of light rays above and below the horizontal cut. The reflecting surface 26 has a focus located at the second focus F2 of the first reflector and is arranged to directly receive light from the second source 27 and which is not reflected on the surface 22 of the fifth reflector 21.

The operating principle of module 102 is as follows:

We will consider for this reason four light rays R7, R8, R9 and R10 coming from the second light source 27.

Since the second light source 27 is arranged at the first focus F4 of the fifth reflector 21, the majority of the rays emitted by the source 27, after being reflected on the internal face 22, is returned to the second focus F2 or in the vicinity of this one. This is the case of the radius R7 which passes along the cutting edge 11. R7 is then reflected on the surface 8 of the second reflector 3 in a direction substantially parallel to the optical axis A1 of the second reflector 3.

Other rays may, after being reflected on the inner face 22, reflect on the reflective bevel 12 of the folder 5; this is the case of R9. R9 will then reflect again on the paraboloidal surface 24 of the sixth reflector 23 and this reflection will be upwards in the plane of the figure. The radius R9 is thus emitted above the cut-off in the lighting beam. This is because the radius R9 originates from a point below the cutoff edge 11.

Other rays, of the R8 type, can pass beyond the edge 11. In such a case, the ray R8 is then reflected on the surface 8 of the second reflector 3 and is also re-emitted above the cutoff in the lighting beam.

Finally, the R10-type rays which are not intercepted by the surface 22 of the fifth reflector are emitted towards the surface 26 of the seventh reflector 25 and then transmitted in a beam above and below the cut. The radius R10 shown as reflecting at the center of the surface 26 is exactly on the cut. However, it is conceivable to construct the surface 26 so that it produces a cut-off beam. This construction would be for example identical to the construction of the reflector 14 of the figure 2 by inverting the beams.

Let us note here that if both light sources 6 and 27 are lit at the same time, an output beam of the high beam or DRL type is obtained; when the first source 6 is only on, there is always a cut-beam type dipped beam or fog lamps. The module 102 thus makes it possible to create a complementary beam by adding light above the cut line of the main beam.

Note also that another arrangement consists in turning the sixth and seventh reflectors 23 and 25 by a positive angle (1 ° in our embodiment) around, respectively, the axis X of the reference and a parallel axis passing by the second light source 27, so as to provide an overlap between the complementary beam and the main beam (the maximum intensity of the sum is then higher and there is more risk of creating a line of contrast between the two beams).

The figure 5 represents a curve 200 of an isophot of the illumination module 102 as represented in FIG. figure 1 with a straight cut edge along the X axis.

Curve 200 shows that a portion having two vanes 201 and 202 of the illumination beam is above the directional limit or cutoff separating the illuminated surface into two zones I (unbroken) and II (above the cutoff ).

The presence of fins 201 and 202 in zone II is due to the absence of field curvature correction in particular after reflection on the third reflector 4. Thus, in theory, all the rays arriving on the reflecting surface 9 and passing along the cutting edge 11 should start again horizontally. In practice, apart from the paraxial approximation, the image projected by the paraboloid 9 is never so clear for points located on either side of the focus F2 according to the X direction and slightly offset on the Z axis. The image of these points is found above the cut and explains the presence of the fins 201 and 202.

Therefore, it is necessary to make a field curvature correction. One solution is to prevent the light from passing through the points likely to provide a beam above the horizontal. We then add an opaque corrective surface to the cutting edge 11 which will prevent the rays coming from the surface 7 and may be troublesome to reach the surface 9 of the third reflector 4. Such a surface determined by standard software simulation means is then contiguous to the cutting edge 11 and has substantially the shape of the hatched portion under the fins 201 and 202 in the plane (F2, X, Z).

However, such an opaque surface can be difficult to achieve because it is necessary, during metallization operations of the reflective surface 10 of the folder 5, to save on a small surface with an acute edge at the end of said reflecting surface 10.

It is therefore desirable to simply add a corrective surface to the edge 11, said corrective surface remaining reflective for reasons of simplicity of manufacture.

However, one can not keep the same corrective surface as described above since the rays intended for the surface 9 and hidden by the reflective corrective surface will then be reflected towards the surface 8 of the second reflector 3 to provide a beam above the clipping, thereby displacing the problem of non-correction of field curvature to the second reflector 3. A solution to this problem is illustrated in FIG. figure 6 .

The figure 6 represents a reflective corrective surface 400 of field curvature used in a module as shown in FIG. figure 1 .

• 1^ère condition : elle empêche les rayons provenant de la surface 7 et susceptibles d'être au-dessus de la coupure d'atteindre la surface 9 du troisième réflecteur 4.
• 2^ème condition : elle appartient à un plan P contenant l'axe F2-X et incliné d'un angle prédéterminé, ici 20°, par rapport au plan (F2, X, Z) de sorte que les rayons gênants bloqués par la surface 400 soient réfléchis vers l'arrière du module 1 et en aucun cas vers la surface réfléchissante 8 du deuxième réflecteur 3.

This surface 400 is in the extension of the cut-off edge 11 and is calculated using a standard simulation software so as to fulfill the following two conditions:

• 1 provided ^era: it prevents the rays from the surface 7 and may be above the cut to reach the surface 9 of the third reflector 4.
• ^2nd condition: it belongs to a plane P containing the axis F2-X and inclined by a predetermined angle, here 20 °, with respect to the plane (F2, X, Z) so that the annoying rays blocked by the surface 400 are reflected towards the rear of the module 1 and in no case towards the reflecting surface 8 of the second reflector 3.

The figure 7 represents an isophote curve 300 of an illumination module as represented in FIG. figure 4 with a cut edge corrected with the surface 400 in the plane P as shown in FIG. figure 6 .

Curve 300 shows that the entire illumination beam is below the directional or cutoff limit, i.e. in zone I.

The field correction surface 400 has been described with reference to the figure 1 but it is clear that it also applies to the other embodiments of the Figures 2 to 4 .

In all embodiments of the Figures 1 to 4 a second solution to avoid fins such as 201 and 202 can be found in a slight modification of the reflective surfaces of the first reflector 2 and the second and third reflectors 3 and 4.

• en référence à la figure 1 :
  • o que la surface 7 du premier réflecteur 2 pouvait ne pas être parfaitement elliptique et avoir d'autres profils spécifiques pour optimiser la répartition lumineuse dans le faisceau d'éclairage produit par le module 1, et que ceci impliquait que le premier réflecteur 2 ne devait pas être parfaitement de révolution,
  • o que les surfaces réfléchissantes 8 et 9 du deuxième 3 et du troisième réflecteur 4 étaient de forme sensiblement paraboloïdales, et
• en référence à la Figure 5,
  • o que la présence des ailettes 201 et 202 dans la zone Il était due à l'absence de correction de courbure de champ notamment après réflexion sur le troisième réflecteur 4.

We noted above:

• with reference to the figure 1 :
  • o that the surface 7 of the first reflector 2 could not be perfectly elliptical and have other specific profiles to optimize the light distribution in the light beam produced by the module 1, and that this implied that the first reflector 2 should not not be perfectly revolutionary,
  • o that the reflective surfaces 8 and 9 of the second 3 and third reflector 4 were substantially paraboloidal shape, and
• with reference to the Figure 5 ,
  • o that the presence of the fins 201 and 202 in the zone II was due to the absence of field curvature correction in particular after reflection on the third reflector 4.

We can therefore take advantage of these remarks to slightly modify the surfaces of the first, second and third reflectors to obtain a correction of the field curvature, and thus eliminate the fins 201 and 202 in the beam emitted by one of the modules. lighting 1, 100, 101 or 102 described above.

Such a correction of the curvature of the field must result in not sending light rays above the cutoff separating the illuminated surface into two zones, that is to say, not sending rays in the zone II of the figure 7 . Under these conditions, the directional limit between the zones I and II can be considered as the infinite image of the cutoff edge 11 of the fourth reflector 5 formed by the second and third reflectors 3 and 4.

The invention therefore consists in using a rectilinear cutoff edge 11 and in forming the image at infinity with the aid of the second and third reflectors 3 and 4, these being constituted by parabolic cylinders, it is to say surfaces such as 8 or 9 on the figure 1 , generated by a line segment perpendicular to the plane of this figure and based on the parabola 8 or 9.

The first reflector 2 must therefore be a surface transforming the spherical wave emitted by the light source 6 into a cylindrical wave, whose generator is parallel to the cutoff edge 11.

• une coupe de ce réflecteur par un plan horizontal est une parabole, et
• la coupe dans un plan vertical contenant la source lumineuse est une ellipse.

The surface of the first reflector 2 is then easily constructed, and thus an ellipso-parabolic surface is obtained:

• a section of this reflector by a horizontal plane is a parabola, and
• the section in a vertical plane containing the light source is an ellipse.

Thus, by producing a lighting module, whose first reflector 2 consists of an ellipso-parabolic surface, whose second and third reflectors 3 and 4 are parabolic cylinders, and whose fourth reflector 5 or folder has an edge straight cut 11 the beam emitted by such a lighting module has the isophote curve 400 represented on the figure 8 .

Curve 400 shows that the totality of the illumination beam emitted by the lighting module which has just been described is below the directional limit or cutoff, i.e. in zone I.

So we see that we get a beam whose cut is particularly sharp and straight, with a simple folder, that is to say whose edge is straight, and therefore very easy to achieve.

Such a design makes it possible to design a second variant of the lighting module according to the present invention, more particularly represented on the figure 9 .

According to this variant, in the module 103, the first and third reflectors are such as those just described, the second reflector is removed, and the folding reflector is arranged so that its reflective face includes the axis optical A2 of the first reflector collector 2.

• Nous considérons pour cela encore trois rayons lumineux R1, R2 et R3 issus de la source lumineuse 6.

The operating principle of the module 103 is deduced from the foregoing:

• We consider for this purpose three light rays R1, R2 and R3 coming from the light source 6.

Since the light source 6 is arranged at the first focus F1 of the first collector reflector 2, most of the rays emitted by the source 6, after being reflected on the internal face 7, are sent back to the second focus F2 or in the vicinity of this one. This is the case of the radius R1 which passes along the cutting edge 11, R1 is then reflected on the surface 9 of the output reflector 4 in a direction substantially parallel to the optical axis A1 of the output reflector 4. Note here that the cutting edge 11 has a bevel 12 defining an oblique surface. This oblique surface 12 is determined so that the cutting edge 11 is not likely to intercept rays reflected by the first reflector 2 and passing beyond the second focus F2.

Other rays may, after being reflected on the inner face 7, reflect on the surface 10 of the folder 5; this is the case of R2. R2 will then reflect again on the paraboloidal surface 9 of the output reflector 4 and this reflection will be downward in the plane of the figure 9 . The radius R2 is thus emitted under the cut-off in the lighting beam.

Other radii, of the R3 type, can pass beyond the edge 11. In such a case, the ray R3 is then reflected on the surface 9 of the output reflector 4 and is also reemitted under the cut in the beam of the beam. 'lighting.

The reflective surface 10 allows to "fold" the images of the light source 6 which are reflected by the elliptical surface 7 of the first reflector 2 to the second focus F2.

The "fold" formed by this "folding" of images contributes to forming a clean cut in the light beam reflected by the output reflector 4.

In order to collect the maximum of light rays emitted by the light source 6, the first collector reflector 2 can extend up to the optical axis A1 of the output reflector 4, as shown on FIG. figure 9 .

Of course, the invention is not limited to the embodiments that have just been described.

Claims (29)

1. Lighting module (1) for a vehicle headlight which provides a first lighting beam of the cut-off type comprising:

   - a first reflector (2) comprising a surface (7) for reflection of the rays of light, the cut-off of which on a plane is an ellipse;

   - at least a first source of light (6) which is arranged in the vicinity of the first focal point (F1) of the said first reflector (2),
   characterised in that the said module (1) comprises:

   - a second reflector (3) which produces a first part of the cut-off beam, and has an optical axis (A1) which passes via the second focal point (F2) of the said first reflector (2) and is perpendicular to the optical axis (A1) of the said first reflector (2);

   - a third reflector (4) which produces a second part of the cut-off beam, and has an optical axis (A1) which passes via the second focal point (F2) of the said first reflector (2) and is perpendicular to the optical axis (A1) of the said first reflector (2);

   - the fourth reflector (5), known as a bender, which is arranged between the said second reflector (3) and the said third reflector (4) and comprises:

   ∘ an edge (11), known as the cut-off edge, which is arranged in the vicinity of the said second focal point (F2) of the said first reflector (2), such as to form the cut-off in the lighting beam;

   ∘ a reflective upper surface (10) which includes the said respective optical axes (A1) of the said second and third reflectors (3, 4).
2. Lighting module (1) according to claim 1, characterised in that the said optical axes (A1) of the said second and third reflectors (3, 4) are combined.
3. Lighting module (1) according to one of claims 1 or 2, characterised in that the said first reflector (2) is arranged at the rear of the said second reflector (3), such that the said first reflector (2) is concealed by the said second reflector (3).
4. Lighting module (1) according to one of claims 1 to 3, characterised in that the said second reflector (3) and the said third reflector (4) have a focal point (F2) which is arranged in the vicinity of the said second focal point (F2) of the said first reflector (2).
5. Lighting module (1) according to one of claims 1 to 3, characterised in that the said second reflector (3) and/or the said third reflector (4) comprise a surface (8, 9) for reflection of the rays of light, the cut-off of which on a plane is a parabola.
6. Lighting module (1) according to one of claims 1 or 2, characterised in that the said second reflector (3) and/or the said third reflector (4) is/are a reflector of the type with a complex surface for reflection of the rays of light.
7. Lighting module (1) according to one of the preceding claims, characterised in that the said source of light (6) is a light-emitting diode.
8. Lighting module (1) according to one of the preceding claims, characterised in that the said cut-off edge (11) is a bevelled edge defining an oblique surface (12), the said oblique surface (12) being determined such that the said cut-off edge (11) does not intercept the rays reflected by the said first reflector (2), and passes beyond the said second focal point (F2).
9. Lighting module (1) according to the preceding claim, characterised in that the said second focal point (F2) of the said first reflector (2) is at the centre of the portion of the line of intersection between the said oblique surface (12) and the said reflective upper surface (10) of the said bender (5).
10. Lighting module (1) according to one of the preceding claims, characterised in that the said first and third reflectors (2, 4) are produced in a single piece and/or the said second and fourth reflectors (3, 5) are produced in a single piece.
11. Lighting module (1) according to one of the preceding claims, characterised in that the said second, third and fourth reflectors (3, 4, 5) are produced in a single piece.
12. Lighting module (100) according to one of the preceding claims, characterised in that it comprises a fifth reflector (14) which receives directly rays of light obtained from the said first source of light (6), the reflective surface (15) of the said fifth reflector (14) being such that it produces a third part of the cut-off beam.
13. Lighting module (100) according to claim 12, characterised in that the said first, third and fifth reflectors (2, 4, 14) are produced in a single piece.
14. Lighting module (100) according to claim 12, characterised in that the said first and fifth reflectors (2, 14) are produced in single piece.
15. Lighting module (101) according to one of claims 1 to 14, which provides a second lighting beam without cut-off , characterised in that it comprises:

    - a reflector (18), known as a reflector without cut-off, which produces the said second lighting beam without cut-off, and has an optical axis (A1) which passes via the second focal point (F2) of the said first reflector (2), and is perpendicular to the optical axis (A1) of the said first reflector (2);

    - a second source of light (20) which is arranged in the vicinity of the focal point (F3) of the said reflector (18) without cut-off.
16. Lighting module (101) according to the preceding claim, characterised in that the reflective surface (19) of the said reflector (18) without cut-off is a substantially paraboloid surface to which a reduction factor is applied according to a direction perpendicular to the optical axis (A2) of the said first reflector (2) and to the optical axis (A1) of the said reflector (18) without cut-off.
17. Lighting module (101) according to claim 15, characterised in that the said reflector (18) without cut-off is a reflector of the type with a complex surface of reflection of the rays of light.
18. Lighting module (102) according to one of claims 1 to 11, characterised in that it comprises:

    - a fifth reflector (21) of the said first reflector (2) which is symmetrical relative to the plane of the reflective upper surface (10) of the said bender (5);

    - a second source of light (27) which is arranged in the vicinity of the first focal point (F4) of the said fifth reflector (21).
19. Lighting module (102) according to claim 18, characterised in that:

    - the said cut-off edge (11) is a bevelled edge which defines an oblique surface (12), the said oblique surface (12) being determined such that the said cut-off edge does not intercept the rays which are reflected by the said first reflector (2) and pass beyond the said second focal point (F2), the said oblique surface (12) being reflective, and receiving part of the rays of light obtained from the said fifth reflector (21);

    - the said module (102) comprises a sixth reflector (23) which receives the rays of light obtained from the said oblique surface (12), the said sixth reflector (23) having a substantially paraboloid surface (24) for reflection of the rays of light, with a focal point which is arranged in the vicinity of the said second focal point (F2) of the said first reflector (2).
20. Lighting module (102) according to one of claims 18 or 19, characterised in that it comprises a seventh reflector (25) which receives directly the rays of light obtained from the said second source of light (27), and has a substantially paraboloid surface (26) for reflection of the rays of light.
21. Lighting module (1) according to one of the preceding claims, characterised in that the said bender comprises a surface (400) for correction of the curvature of the field situated along the said cut-off edge (11), and in the continuity of the said upper surface (10) of the said bender (5), such that no ray obtained from the said first reflector (2) and returned to the said third reflector (4) goes beyond the said cut-off.
22. Lighting module (1) according to the preceding claim, characterised in that the said correction surface absorbs the light.
23. Lighting module (1) according to claim 21, characterised in that the said correction surface (400) is reflective, and is inclined by a specific angle relative to the plane of the said reflective upper surface (10) of the said bender, such that the rays obtained from the said first reflector (3), which would have been returned above the cut-off in the absence of the said correction surface, are entirely reflected in a direction opposite the direction of the said first lighting beam.
24. Lighting module (1) according to one of claims 1 to 20, characterised in that the first reflector (2) consists of an ellipso-parabolic surface.
25. Lighting module (1) according to the preceding claim, characterised in that the second reflector (3) is a parabolic cylinder.
26. Lighting module (1) according to claim 24 or claim 25, characterised in that the third reflector (4) is a parabolic cylinder.
27. Lighting module for a vehicle headlight which provides a lighting beam of the cut-off type comprising:

    - a first collector reflector (2) comprising a surface (7) for reflection of the rays of light, the cut-off of which on a plane is an ellipse;

    - at least a first source of light (6) which is arranged in the vicinity of the first focal point (F1) of the said first reflector (2), this source comprising an LED,
    characterised in that the said module comprises:

    - an output reflector (4) which produces a cut-off beam, and has an optical axis (A1) which passes via the second focal point (F2) of the said first reflector (2) and is perpendicular to the optical axis (A2) of the said first reflector (2);

    - a reflector (5), known as a bender, which is arranged between the said first collector reflector (2) and the said output reflector (4), and comprises:

    ∘ an edge (11), known as the cut-off edge, which is arranged in the vicinity of the said second focal point (F2) of the said reflector (2), such as to form the cut-off in the lighting beam;

    ∘ a reflective upper surface (10) which includes the said optical axis (A2) of the first collector reflector (2),
    and in that the source of light (6) emits most of its light energy in the direction opposite that of the emission of the lighting beam of the cut-off type.
28. Lighting module according to claim 27, characterised in that the first reflector (2) consists of an ellipso-parabolic surface.
29. Lighting module according to claim 27 or 28, characterised in that the third output reflector (4) is a parabolic cylinder.

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