Elliptical lighting module without screen emitting a low beam and headlamp comprising the same

The present invention relates to a lighting module and a projector motor vehicle lighting.

The present invention relates more particularly to a module light for a motor vehicle headlight producing a light beam cut-off type, comprising, arranged from back to front overall along a longitudinal horizontal optical axis, a reflector of the elliptical type which delimits a volume of reflection for light rays and comprises a substantially elliptical surface reflection, at least one light source which is arranged in the vicinity a first focus of the reflector, and a convergent lens whose plane Focal is arranged close to the second focus of the reflector.

The projectors of the elliptical type or optical projectors image reproduction, are well known, especially for the production a lighting beam with cutoff.

by cleavage illumination beam means a beam light having a directional limit or cut-off, above which the emitted light intensity is low.

The functions of low lights, fog lights and Codes are examples of cutoff light beams, accordance with European legislation.

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

The cache is used to mask the light rays coming from the light source and reflected by the reflector towards the lower part of focal plane of the convergent lens, and which would, in the absence of cache, emitted by the headlight above the cut.

A disadvantage of this type of projector is a part important source of the emitted light energy is dissipated in the backside cache. Furthermore, this type of module allows dual function, namely the "road" and "code" function function.

One solution to this problem is disclosed in US Patent 4 914 747.

In this document is described a lighting module for a a motor vehicle headlight producing a lighting beam of the cut type, comprising, arranged from back to front overall a longitudinal horizontal optical axis, two reflectors type elliptical that each delimits a volume of reflection for rays light and which each has a substantially elliptical surface reflection, two light sources which are arranged respectively vicinity of a first focus of each reflector, and a lens convergent whose focal plane is arranged in the vicinity of the second focus the first reflector, said first reflector having a surface horizontal plane of reflection, the upper face of which is reflective, which delimits vertically downwards the reflection volume of the beam emitted by the first light source and having an end edge before, said cut-off edge, which is arranged in the vicinity of the second focus of the reflector, so as to form the cutoff in the beam lighting.

According to this prior art, the first light source formed of a filament is equipped with a bottom cover providing a single beam upwardly emitted by this source. The first elliptical reflector him that is associated can be designed in an optimized manner according to this first source code to complete the function.

Against by the second light source, also a filament, can emit as much upward than downward. If the second elliptical reflector associated therewith can be designed optimized according to the second power source to perform the function road, there is a top beam defined by the choice of this second light source and reflecting on the first defined reflector meanwhile by the choice of the first light source. If this beam once thought involved in road function, this function can not be optimized as dependent on criteria relating to the function code, in terms of the first reflector.

This results in an uncontrolled and random arrangement efficiency or at least require extensive testing for functions desired.

The invention solves this technical problem and to do that, she proposes a lighting module for a vehicle headlight automobile carrying a cut-type illumination beam, comprising, arranged from back to front overall along an axis longitudinal horizontal optical, two reflectors of the elliptical type each defines a volume of reflection for light rays which each has a substantially elliptical reflection surface, two light sources which are respectively arranged adjacent to a first focus of each reflector and a lens with the focal plane is arranged in the vicinity of the second focus of the first reflector, said first reflector having a flat surface horizontal reflection, the upper face of which is reflective, which delimits vertically downwards the reflection volume of the beam emitted by the first light source and having an end edge before, said cut-off edge, which is arranged in the vicinity of the second focus the reflector, this flat surface of the first reflector being arranged generally in a horizontal plane through the foci of the first reflector, characterized in that the second light source is arranged to emit a light beam only towards the second reflector, at least one of light sources consisting of a light emitting diode.

Thus, each light source emits in a half volume of limited thinking by the corresponding elliptical reflector, so independent. This allows to control their function and radiation easily and accurately.

Thanks to the lighting module according to the invention, the majority of the flow light emitted by each source is used in the light beam produced by the module, in order to achieve the dual lighting function associated regulatory, preferably the "road" and function "Code" ..

According to a preferred embodiment, this arrangement consists in that the two light sources are separated by a rollover opaque.

Preferably, the second focal points of the first and second elliptical reflectors are substantially coincident.

Advantageously, the horizontal flat surface of reflection, the upper face of which is reflective, consists of a piece transparent bearing a reflective coating.

This feature limits the hole or dead zone light corresponding to the image of the thickness of said face by reflecting the light beam reflected by the first reflector the thickness of said reflective coating can be achieved by a vacuum deposition of aluminum for example, which is of a thickness between about 500 nm and about a few micrometers, the order of magnitude of some visible wavelengths.

Moreover, this transparent member also has a function optical relation to the optical beam reflected by the second reflector. Indeed, it is crossed by the beam.

To minimize optical losses in this crossing of Preferably, said transparent part comprises a lower face ball centered on the second focus of the second elliptical reflector.

Thus the light rays emitted by reflection on the second reflector are normal to said bottom face.

Preferably, the substantially elliptical surface of the first reflector is formed by a piece angular sector substantially revolution, around the longitudinal optical axis, and in that this area angular extends vertically above the flat surface of reflector.

Preferably, the substantially elliptical surface of the second reflector is formed by a piece angular sector substantially revolution about an axis of said revolution.

And preferably, the optical axis of the first reflector and the axis Revolution of the second reflector intersect.

According to other characteristics of the invention:<ul><li>the flat surface of the reflector may extend longitudinally rearward, from its cut-off edge, at least until near the first focus of the reflector;</li><li>the light source associated with the first reflector is arranged in the module so that its axis of light scattering or substantially perpendicular to the planar surface of said reflector;</li><li>the flat surface of the cut edge of the first reflector has a curved profile, in the horizontal plane, so as to follow overall the curvature of the focal plane of the lens.</li></ul>

The invention also relates to a lighting projector motor vehicle comprising at least one lighting module as previously specified and for a dual lighting function.

Preferably, this dual function comprises the function Lighting mode "code" and fashion lighting function "Road".

Other features and advantages of the invention will on reading the detailed description which follows for the understanding of which is made to the attached drawings among which:<ul><li>Figure 1 is a vertical sectional view which shows schematically a preferred embodiment of the module Lighting according to the invention;</li><li>Figure 2 is a perspective view showing partially this preferred embodiment of the lighting module according to the invention;</li><li>Figure 3 is a top view which shows schematically the lighting module of Figure 1;</li><li>Figure 4 is a side view which schematically illustrates the light path in the light source module of FIG 1; </li><li>FIG 5 is a similar view to that of Figure 2, which shows a second embodiment of the lighting module according to the invention;</li><li>FIG 6 is a similar view to that of Figure 2, which represents an alternative embodiment of the lighting module of the Figure 1 having a plurality of light emitting diodes;</li><li>Figure 7 is a front view which schematically shows a Vehicle lighting headlight comprising modules Lighting according to the invention and producing a light beam regulatory crossing;</li><li>Figure 8 is a schematic perspective view of the module lighting shown in Figure 1;</li><li>Figure 9 is a schematic representation of an image of the projection of the light beam emitted by the module, according to a first module of the mode of operation according to the invention</li><li>Figure 10 is a schematic representation of an image of the projection of the light beam emitted by the module, according to a second module of the mode of operation according to the invention.</li></ul>

schematically shown in Figure 1 a module Light 10 which is constructed according to the teachings of the invention.

Conventionally, the illumination module 10 comprises, arranged from back to front along a longitudinal horizontal optical axis AA, a first reflector 12 of the elliptical type, a first source light 14 which is arranged in the vicinity of a first focus F1 of first reflector 12, and a converging lens 16, the focal plane is arranged in the vicinity of the second focus F2 of the first reflector 12.

The first reflector 12 and the lens 16 form a part of the optical system of the lighting module 10.

The optical axis AA defined here, not limited, a direction horizontal longitudinal and a rear forward orientation, which corresponds to a left to right direction in FIGS. The axis optical AA is for example substantially parallel to the longitudinal axis of a vehicle (not shown) equipped with the lighting module 10.

In the following description, are not limited to, use a vertical orientation which corresponds to a downward direction in Figure 1.

The lens 16 is here a part of revolution around of the longitudinal optical axis AA. The lens 16 comprises, vis-à-vis first reflector 12, a transverse inlet surface 17 to the light rays.

According to the embodiment shown here, the first reflector 12 has an elliptical surface 18 which is designed as a angular sector part substantially of revolution, and which extends in the half space located above a horizontal axial plane by the longitudinal optical axis AA.

The internal face 20 of the elliptical surface 18 is reflective.

Note that the elliptical surface 18 may not be perfectly elliptical and may have several specific profiles provided for optimize light distribution in the product illumination beam by the module 10, according to the lighting function "code" conducted by the Module 10. This therefore implies that the reflector is not perfectly revolution.

According to the teachings of the invention, the first reflector 12 comprises a horizontal flat surface 22 whose front upper 24 is reflective.

The first reflector 12 delimits a volume of reflection for light rays emitted by the first source 14, ie a volume wherein the light rays are emitted and wherein the radii light are reflected. This volume of reflection is delimited in its upper part, by the internal reflection face 20 of the surface elliptical 18 and vertically downward by the reflecting face 24 of the flat surface 22.

The flat surface 22 extends here in a horizontal axial plane.

Figures 2-7 show only the first reflector 12, the lens 16 and the planar surface 22.

The flat surface 22 is bounded at the rear, at its intersection with the elliptical surface 18, by an elliptical edge 26, and to the front, a longitudinal front end edge 28. It can be provided alternatively that the planar surface 22 is bounded at the rear by a segment of perpendicular to the axis and from the adjacent source 14, forward of the latter.

The front end edge 28 of the flat surface 22 is arranged vicinity of the second focus F2 of the reflector 12, so as to form a sufficiently sharp cutoff in the lighting beam produced by the lighting module 10.

In the following description, therefore we designate this edge front end 28 by "cutoff edge 28".

The focal plane of the lens 16 in a horizontal plane passing through the focus F2 of the lens 16, form a curved profile, concave forward. According to the embodiment, the curved shape of the profile is more or less complex, and can be likened to a first approximation arc. Therefore, preferably, the cut-off edge 28 a a curved profile, in the horizontal plane, so as to follow overall profile of the focal plane of the lens 16.

According to the embodiment shown here, the flat surface reflecting 22 includes a rear section 30 semi-ellipsoidal, which is delimited by the elliptical edge 26, and by the diameter 32 of the edge 34 semi-circular elliptical surface 18.

The reflective planar surface 22 comprises a front portion 36 generally isosceles trapezoidal, which is delimited by the diameter 32 of the elliptical surface 18, by two lateral edges 38, 40, and by the edge of 28 cut.

According to the embodiment shown here, the width cross the front section 36 increases progressively towards forward, so that the transverse width of the cutoff edge 28 is substantially equal to the diameter of the lens entrance surface 16.

According to an alternative embodiment as shown in Figure 3, the planar surface 22 may comprise a portion only before 36, which extends axially rearwardly from the cutoff edge 28 to a certain place of the optical axis AA between the first F1 and second homes F2 of the reflector 12.

Advantageously, the light source 14 is provided for give its light energy in less than a "half space" located above the planar surface 22, and to emit its light energy towards the inner face 20 of the elliptical surface 18.

Advantageously, the light source 14 is a diode emitting encapsulated 44.

is defined here as light-emitting diode 44, the junction that produces light energy as well as the globe or capsule, dissemination light, enveloping the upper part of the junction.

Conventionally, the light emitting diode 44 is mounted on an electronic plate holder 42, which is shown in Figure 4, and which is arranged here in parallel under the flat surface 22.

The light emitting diode 44 has an axis of diffusion light BB which is here substantially perpendicular to the surface 22 planar.

The LED 44 emits its light energy in a solid angle generally centered about its axis of diffusion light BB, and less than 180 degrees.

This arrangement allows the diode 44 to emit most of its light energy towards the internal face 20 of the elliptical surface 18.

The principle of operation of the lighting unit 10 along the invention is as follows.

It is assumed that the light source 14 is of small size around a point coincident with the first focus F1 of the reflector 18 elliptical.

Initially, the emitted light rays is considered by the light source 14 which pass above the cut-off edge 28, which will be designated by primary rays R1.

As the light source 14 is arranged at the first focus F1 of the elliptical reflector 18, most of the primary rays R1 emitted by the source 14, after being reflected on the internal face 20 of the elliptical surface 18, is returned to the second focus F2 of the reflector 18, or in the vicinity thereof.

These primary light rays R1 form, the home of the F2 lens 16, a concentrated light image that is projected at the front of the lighting module 10 by the lens 16 in a direction substantially parallel to the longitudinal axis AA, but oriented low.

Secondly, we consider the light rays R2 emitted by the source 14 which would pass below the cutoff edge 28, if there were not the flat surface 22, and which will be designated by R2 secondary rays.

These secondary light rays R2 are reflected by the face internal 20 of the elliptical surface 18 towards the reflective flat surface 22, so that they are reflected a second time towards the front.

During this second reflection, the secondary light rays R2 are transmitted to the upper part of the inlet surface 17 of the lens 16. Therefore, due to its convergence properties, lens 16 deviates the secondary light rays R2 down. The R2 secondary light rays are emitted under the cutoff in the lighting beam, in the same area as that which are R1 emitted rays.

More place of reflection on the flat surface 22 with a radius R2 secondary light is close to the cutoff edge 28, so close the focal plane of the lens 16 over the direction of the light beam secondary R2 at the exit of the lens 16, is close to a direction parallel to the longitudinal axis AA.

An advantage of the lighting module 10 of the invention is that its optical system 11 does not obscure an important part of the rays light emitted by the source 14, as is the case in a module conventional lighting with a cache.

The reflective flat surface 22 can "fold" the images of the light source 14 that are reflected by the surface 18 elliptical reflector 12 at the second focus F2 of the reflector 12.

Indeed, in the absence of the flat surface 22, some of these images should overlap the edge formed by the cut-off edge 28, in a vertical plane generated by the cut-off edge 28. Each image would then comprise an upper portion located above the edge cut 28 and a lower portion located below the edge cut 28. With the reflective flat surface 22, the portion bottom of each image is reflected upward, as if the bottom portion was folded over the upper portion, so that these image portions are superimposed above the cutoff edge 28, the vertical plane generated by the cutoff edge 28.

The "fold" formed by the "folding" of images helps train a sharp cutoff in the lighting beam projected by the lens 16.

The light source module 10 according to the invention also presents particular advantages in connection with the use of a diode emitting 44 as the light source 14 in a module lighting.

Indeed, the image of the virtual source corresponding to a diode is generally round and diffuse.

To make a cut in a lighting beam from a light source module using a light source and an optical Fresnel, or using a light source and a type of reflector complex surface, it is necessary to align the edges of the images of the light source on the measurement screen used to validate the beam Regulatory lighting.

When the light source is a filament, its virtual image the overall shape of a rectangle, so it is relatively easy to make a clean break by aligning the edges of the rectangles.

When the light source is a diode, it is much more difficult to achieve a clean cut aligning images corresponding, round shapes.

This difficulty could be overcome by using a diaphragm with the diode, but would then lose a significant amount of the light energy produced by the diode.

The light source module 10 according to the invention allows a clean cut with a diode 44, because it projects on the front image of a edge of the optical system 11, i.e. the image of the cut-off edge 28.

The shape of the cutoff in the lighting beam is therefore determined by the profile of the cut-off edge 28, a projection on vertical and transverse plane.

Another difficulty for the embodiment of a light module from a diode is because the distribution of energy light in the light beam emitted by the diode is not homogeneous. Therefore, it is very difficult to make a bundle homogeneous illumination from direct images of the diode.

The illumination module 10 according to the invention overcomes this difficulty by exploiting a property of elliptical lighting modules which is "mixing" the images of the light source in the second focus F2 of the reflector 12, which improves the uniformity of the beam lighting product.

An advantage of the lighting module 10 according to the invention is that it exploits the property of encapsulated diodes 44 of emitting overall in a half space, which allows capture of more than eighty percent of the luminous flux emitted by the diode 44, whereas in an elliptical headlight traditional code, it captures less than fifty percent lumen.

According to a first embodiment, which is shown schematically in Figures 2 to 4, the lighting module 10 is realized by an assembly of discrete elements.

The light source module 10 includes, for example, an element 18 forming the elliptical portion of the reflector 12, an element 22 forming the planar surface of the reflector 12, and an element 16 forming the lens convergent.

The inner surface of the elliptical portion 18 and the upper face of the flat surface 22 are for example coated with a material reflective.

In the case where the light source 14 is a diode emitting 44, given the low heat dissipation of this type of source, relative to the lamps, it is possible to achieve the discrete elements in the form of polymeric parts, assemblies for example by fitting.

The lens 16 may be a Fresnel lens.

According to another embodiment of the invention, which is shown schematically in Figure 5, the optical system 11 of light module 10 is made of a single solid optical piece, transparent material, for example PMMA (polymethyl methyl).

Full optical part is made for example by molding or by machining.

To allow the reflection of light rays emitted by the source 14 into the volume of reflection delimited by the reflector 12, the outer surface of the elliptical portion 18 of the reflector 12 and the surface external, here below, the planar surface 22 of the reflector 12 are coated with a reflective material.

For some portions of the reflector 12, can be used total reflection properties in a medium of index greater than air to cause reflection of light rays in the volume reflection delimited by the reflector 12, without using material reflective. These reflector portions 12 will then form slightly different from that of a pure ellipsoid.

According to this second embodiment, the light rays which are emitted by the light source 14 propagate within the the material constituting the optical system 11 of the lighting module 10, then they come out of the optical system 11 from the front side of the lens convergent 16.

The fact that the light rays propagate within a material, in the second embodiment, while the rays light propagating in air, in the first embodiment, has no significant influence on the module operating principle light 10 according to the invention.

Advantageously, the reflective planar surface 22 comprises a cavity of complementary shape to the capsule of the diode emitting 44.

For example, if the capsule of the diode 44 has a shape hemispherical, the cavity is substantially hemispherical.

In a variant of this second embodiment, the reflector 12 is made of a single piece of transparent material, which is separate from the part forming the convergent lens 16.

According to an alternative embodiment of the invention, which is shown in Figure 6, the light source 14 can be achieved means more light emitting diodes 44.

Note that the light emitting diodes 44 must be very close to each other, so that they are arranged generally the first focus F1 of the reflector 12.

For example, according to Figure 6, two diodes 44 are aligned, preferably in a direction perpendicular to the axis longitudinal optical AA.

The resulting light source 14 is then equivalent to a light source extended in width because the illumination beams produced by each LED 44 overlap.

This arrangement of LEDs 44 allows to expand the beam light produced by the light module 10.

Advantageously to realize a lighting function regulatory, to cut, for example a lighting function "code" there is provided a vehicle headlight by means of a plurality of modules of 10 identical light running simultaneously.

The light source module 10 are arranged in parallel, ie that their optical axes AA are substantially mutually parallel.

Thus, the light beams produced by each of the modules lighting 10 are superimposed on the front of the vehicle so as to form to cut the regulatory lighting beam.

For example, there is shown in Figure 7 a projector 46 vehicle which performs a code function, which uses four lighting modules 10 identical.

As the cross beam of light must have a cut having an inclined part by a determined angle, by example fifteen degrees, two lighting modules 48 of the projector 46 are rotated fifteen degrees about their longitudinal optical axis AA, so as to produce an illumination beam having a cutoff inclined five degrees with respect to a horizontal plane.

The other two illumination modules 50 form a beam light having a horizontal cutoff.

The superposition of the light beams produced by the four The light source module 10 then forms an illumination beam regulatory having a horizontal portion and an inclined portion fifteen degrees.

According to an alternative embodiment (not shown) of the invention, the light source 14 may be formed by the free end of a beam optical fiber.

A disadvantage of optical fibers is that they form a light source with a light heart and a dark ring, due to the cladding surrounding the core of the fiber.

This type of light source, when used in a lighting projector of the vehicle using for example a reflector type complex surface, thus forms, in the light beam, the images as pixels surrounded by a dark area due to the sheath.

An advantage of the lighting module 10 according to the invention is that it mixes all the images of the light source 14 second focus F2 of the reflector 12 so that is not found in the illumination beam the pixels of the optical fiber.

Now back to Figure 1, associated with FIG 8. Moreover, from what has already been described specifically above, to fill a dual function, namely the "code" function but also the function "highway", the module according to the invention, intended to equip a projector motor vehicle lighting, also comprises arranged from back to front overall along the optical axis horizontal longitudinal AA, a second reflector 12 'of the elliptical type which delimits a reflection volume for light rays and which comprises a substantially elliptical reflection surface 18 ', 20', a second source light 14 'which is arranged in the vicinity of a first focus F1' of the second reflector 12 '. This second light source 14 is arranged so as to emit a single light beam downwards.

The second reflector 18 'and the second light source 14' may be similar to the first reflector 18 and the first source Light 14. They can have all the characteristics corresponding already mentioned above, without that these are explicitly included here.

To do this, the two light sources 14, 14 'to control Selective which are preferably two light emitting diodes or two sets of light emitting diodes are separated by a opaque shroud 60 which possibly may contain a radiator and control circuits.

As seen above, the substantially elliptical surface the first reflector 12 is formed by an angular part sector substantially of revolution, around the longitudinal optical axis AA, and this angular sector extends vertically above the flat surface 22 of the reflector.

The substantially elliptical surface of the second reflector is, for to it, formed by a piece angular sector substantially revolution, about its axis of revolution said A'-A 'and, advantageously, the optical axis AA of the first reflector and the axis of A A'revolution 'of the second reflector intersect.

The second elliptical reflector 12 'is arranged to have its second focus substantially coincides with the second focus F2 of the first reflector 12. The optical axis A of the first reflector and the axis of revolution A'-A 'of the second reflector therefore essentially cut the second focus F2.

The horizontal flat reflection surface 22, whose face upper 24 is reflective, consists of a transparent part 22 'bearing a reflective coating on its upper face and forming the reflective top surface 24. Advantageously, this piece transparent 22 'has a spherical bottom surface 22A centered substantially on the second focus F2. His side face 22B faces the lens 16 is in turn preferably defined by a surface set defined by vertical lines connecting the top edge 34 the first reflector 12 at the second focus F2.

Preferably, this transparent member 22 'is made of PMMA (Polymethyl methacrylate) and the reflective coating consists a vacuum deposition of aluminum.

The optical module operation has already been mentioned above as regards the first elliptical reflector 12 with its surface 22 reflective associated in particular with reference to Figure 4.

To summarize, with reference to Figure 1, during the operating the first light source 14, most primary rays emitted by the source 14, after reflected on the internal face 20 of the elliptical surface 18, is returned to the second focus F2 of the reflector 18 or in the vicinity thereof. The Rays secondary light are reflected by the inner face 20 of the surface elliptical 18 toward the flat reflecting surface 22, so that they think again forward, this reflective surface 22 operating according to a "collapsing".

An image I1 of the projection of the light beam emitted by the module output from the lens 16, is shown schematically in Figure 9. This first module function is particularly the "code" mode of a motor vehicle headlight.

During the simultaneous switching of the second source of light 14 ', the majority of the primary rays R1' emitted by the source 14 ', after being reflected on the internal face 20 of the surface elliptical 18, is returned to the second focus F2 or near this one. These rays normal to the bottom surface 22A of the workpiece Transparent 22 'through it without optical loss, losses close suffered by glass reflection on surface 22A, and are then returned by the lens 16 above the axis AA.

An image of the projection of the light beam emitted by the module output from the lens 16, is shown schematically in Figure 10. A image I2 there is an adjunct to the previous image I1. this second Module function is particularly "road" mode of a motor vehicle headlight.

Given the transparency of the part 22 'and the thickness reduced and not visible from the reflective coating 24, the two images in question I1 and I2 are in the eye and form a contiguous beam single light.