EP1881263B1 - Lighting or signalling device comprising a curved light guide - Google Patents

Description

The invention relates to a lighting or signaling device for a motor vehicle which comprises a light-guiding sheet.

• une source lumineuse ponctuelle qui émet des rayons lumineux radialement autour d'un axe de source ;
• une nappe de guidage des rayons lumineux qui comporte une tranche d'entrée des rayons lumineux, une tranche avant de sortie des rayons lumineux tangentiellement à la nappe de guidage, et une tranche arrière de réflexion des rayons lumineux issus de la source lumineuse en direction de la tranche de sortie.

The invention more particularly relates to a lighting or signaling device for a motor vehicle which is capable of emitting a linear beam generally in the direction of an optical axis, and which comprises:

• a point light source which emits light rays radially around a source axis;
• a guide strip of the light rays which comprises an entrance slice of the light rays, a front slice of light rays coming tangentially to the guide ply, and a rear slice of reflection of the light rays coming from the light source in the direction of the output slice.

It is common to gather in a single package several lighting and / or signaling functions, so as to simplify the electrical wiring of these various functions in a motor vehicle. The document FR 2813 654 describes a headlamp comprising a device according to the preamble of claim 1. In addition, the shape of the lighting and / or signaling lights plays a leading role in the search for a style and an original aesthetic that will allow the vehicle automobile to be recognized by far.

To solve these problems, it is known to equip the vehicle with light guides. A light guide is a cylinder of transparent material that forms a kind of "pipe" in which light rays enter through a first input end. The light rays are then guided along the light guide by successive total reflections on its cylindrical outer face.

A rear portion of the cylindrical face of the light guide has irregularities, such as diffusion streaks, which make it possible to diffuse part of the light rays towards the front of the light guide. whereby a portion of the scattered light rays exit the light guide through the opposite portion of the cylindrical face to form a light beam.

The light guide may for example be shaped into a ring that surrounds the front perimeter of a low beam headlamp so as to emit an annular beam of light. The input end portion of the light guide is then bent so that the input end of the light rays is arranged outside the ring formed by the light guide.

However, such a solution does not make it possible to obtain a high intensity light beam. Indeed, the light rays emitted by the light source are guided in a random and unordered manner within the light guide. Moreover, only a portion of the light rays is diffused outwards by the irregularities. As a result, the light beam obtained by such a device is very low even if the light source arranged at the input end of the light guide is very powerful.

However, certain lighting and signaling functions require a very intense light beam to comply with the regulations in force. The light guide is not adapted to perform such functions.

In addition, the appearance of the annular beam obtained is highly inhomogeneous, in particular for the following two reasons.

On the one hand, the material constituting the lighting or signaling device causes a certain absorption of the light rays which pass through it, which results in losses that are all the greater due to the distance away from the light source. As a result, the brightness in the vicinity of the light source is greater than at a distance from this source, and therefore a lack of homogeneity.

• la nappe de guidage présente une forme galbée et comporte une zone de couplage avec la source lumineuse conformée de manière à ce que les rayons lumineux émis par ladite source lumineuse soient propagés radialement au niveau de ladite zone de couplage autour d'un axe de source,
• la nappe de guidage est conformée de manière à ce que les rayons lumineux se propagent dans des plans méridiens de propagation incidents normaux à la nappe entre la source lumineuse et la tranche de réflexion, dans des plans de propagation réfléchis normaux à la nappe entre la tranche de réflexion et la tranche de sortie, et
• la tranche de réflexion est conformée de manière à ce que les plans de propagation réfléchis présentent une orientation par rapport à l'axe optique telle que ledit dispositif d'éclairage soit susceptible d'émette un faisceau lumineux linéaire selon un axe optique globalement longitudinal.

On the other hand, part of the light rays introduced into the light guide by the bent input portion directly reaches the opposite face of the light guide thus causing the appearance of a very bright point relative to the remainder of the annular beam. lighting or signaling device for a motor vehicle comprising a light source and a light-ray guide sheet which comprises an entrance slice of the light rays, a front slice of light rays tangential to the guide ply, and a slice rear reflection of light rays from the light source towards the output edge, wherein:

• the guide ply has a curved shape and comprises a coupling zone with the light source shaped so that the light rays emitted by said light source are propagated radially at said coupling zone around a source axis,
• the guide ply is shaped in such a way that the light rays propagate in normal meridian propagation planes incident to the ply between the light source and the reflection slice, in normal reflected propagation planes to the sliver between the slice of reflection and the output slice, and
• the reflection slice is shaped so that the reflected propagation planes have an orientation with respect to the optical axis such that said lighting device is capable of emitting a linear light beam along a generally longitudinal optical axis.

• les plans de propagation réfléchis sont parallèles à l'axe optique du dispositif d'éclairage ;
• les plans de propagation réfléchis sont orthogonaux à la tranche de sortie ;
• au moins une première portion arrière de la nappe de guidage qui est délimitée par un secteur angulaire s'étendant depuis l'axe de source et qui enveloppe la tranche de réflexion, présente une forme de portion de sphère de base ;
• l'axe de source passe par le centre de la sphère de base ;
• une deuxième portion avant de la nappe de guidage forme un solide de révolution autour de l'axe optique qui passe par le centre de la sphère de base ;
• les plans de propagation réfléchis sont sécants selon l'axe optique ;
• au moins deux nappes de guidage sont agencées en une première strate, au moins une troisième nappe de guidage étant agencée en une deuxième strate, chaque nappe de guidage étant une portion d'une sphère de base ;
• les nappes de guidage de la première strate sont des portions d'une première sphère de base commune, et en ce que les nappes de guidage de la deuxième strate sont des portions d'une deuxième sphère de base commune, toutes les nappes de guidage étant centrées sur un centre commun ;
• les nappes de guidage possèdent des axes différents et des rayons de courbures différents ;
• la tranche de sortie des rayons lumineux comporte des moyens pour définir l'ouverture du faisceau lumineux autour de la direction de l'axe optique dans le plan de propagation réfléchi ;
• la tranche de sortie est conformée à la manière d'une lentille pour dévier les rayons lumineux par réfraction ;
• la nappe de guidage est plane ;
• ladite tranche de sortie forme un angle avec la normale à l'axe optique en plusieurs de ses points et est susceptible de réfracter les rayons lumineux sortant, la tranche de réflexion étant conformée de manière à ce que les plans de propagation réfléchis aient une orientation telle par rapport à la tranche de sortie, que les rayons lumineux soient globalement parallèles ou parallèles à l'axe optique une fois réfractés par ladite tranche de sortie ; en l'absence de stries sur la tranche de sortie les rayons lumineux réfractés par la tranche de sortie seront parallèles à l'axe optique ; en présence de stries étalant horizontalement la lumière, les rayons lumineux réfractés par la tranche de sortie seront

According to other features of the invention:

• the reflected propagation planes are parallel to the optical axis of the lighting device;
• the reflected propagation planes are orthogonal to the output slice;
• at least a first rear portion of the guide ply which is delimited by an angular sector extending from the source axis and which envelops the reflection slice, has a base sphere portion of shape;
• the source axis passes through the center of the base sphere;
• a second front portion of the guide ply forms a solid of revolution about the optical axis passing through the center of the base sphere;
• the reflected propagation planes are intersecting along the optical axis;
• at least two guide plies are arranged in a first layer, at least one third guide ply being arranged in a second layer, each guide ply being a portion of a base sphere;
• the guide plies of the first stratum are portions of a first common base sphere, and in that the guide plies of the second stratum are portions of a second common base sphere, all the guide plies being centered on a common center;
• the guide plies have different axes and different radii of curvature;
• the light ray output wafer comprises means for defining the opening of the light beam around the direction of the optical axis in the reflected propagation plane;
• the output wafer is shaped like a lens to deflect the light rays by refraction;
• the guide sheet is flat;
• said output wafer forms an angle with the normal to the optical axis at a plurality of its points and is capable of refracting the outgoing light rays, the reflection slice being shaped so that the reflected propagation planes are oriented in such a way that relative to the output wafer, that the light rays are generally parallel or parallel to the optical axis once refracted by said output wafer; in the absence of streaks on the output wafer, the light rays refracted by the output wafer will be parallel to the optical axis; in the presence of streaks horizontally spreading the light, the light rays refracted by the exit slice will be

• ladite tranche de sortie est globalement plane, la tranche de réflexion présentant au moins une forme parabolique dont la directrice forme un angle avec la normale à la tranche de sortie tel que les rayons lumineux soient globalement parallèles ou parallèles à l'axe optique une fois réfractés par ladite tranche de sortie ; en l'absence de stries sur la tranche de sortie les rayons lumineux réfractés par la tranche de sortie seront parallèles à l'axe optique ; en présence de stries étalant horizontalement la lumière, les rayons lumineux réfractés par la tranche de sortie seront globalement parallèles à l'axe optique, le faisceau sortant de chaque strie sera centré sur un axe parallèle à l'axe optique ;
• la tranche de sortie est galbée, la tranche de réflexion présentant une forme complexe telle que pour tout point de la tranche de sortie, tout rayon réfléchi par la tranche de réflexion arrivant en ce point de la tranche de sortie est réfracté parallèlement à l'axe optique ;
• la tranche de sortie comporte des moyens pour définir l'ouverture du faisceau lumineux dans un plan tangent à la nappe de guidage ;
• la tranche de sortie comporte des stries qui sont susceptibles de dévier les rayons lumineux sortant par réfraction dans un plan tangentiel à la nappe de guidage ;
• la nappe de guidage comporte des trous qui sont agencés à proximité du bord de sortie, les rayons lumineux étant déviés de leur trajectoire dans un plan tangentiel en traversant la paroi du trou avant de rentrer de nouveau dans la nappe de guidage en direction de la tranche de sortie ;
• les trous sont alignés en quinconce parallèlement à la tranche de sortie ;
• la tranche d'entrée des rayons lumineux comporte une portion avant qui est conformée de manière à disperser les rayons lumineux issus de la source lumineuse se dirigeant directement vers la tranche de sortie ;
• la source lumineuse est une LED à émission radiale et la nappe de guidage comprend un orifice ayant une tranche périphérique qui correspond à ladite tranche d'entrée, ladite LED à émission radiale étant placée à l'intérieur dudit orifice ;
• la source lumineuse est une LED à émission axiale et la nappe de guidage comprend une surface de réflexion correspondant à une forme complémentaire à un cône dont l'axe de symétrie correspond à l'axe de source de la source lumineuse, cette surface de réflexion étant agencée en vis-à-vis de la tranche d'entrée afin de diriger les rayons lumineux radialement dans la nappe de guidage ;
• préférentiellement la surface complémentaire comprend une partie avec un profil conique et une partie plane, la partie avec le profil conique étant entourée par ladite tranche de réflexion et ladite partie plane étant orientée en regard de la tranche de sortie de manière à ce que les rayons émis au niveau de la partie plane soient réfléchis parallèlement à une direction privilégiée, par exemple l'axe optique ; ainsi, l'ensemble des rayons arrivant sur la forme au profil conique sont réfléchis vers la tranche de réflexion, alors que ceux qui ne pourraient pas atteindre cette tranche de réflexion si la surface complémentaire avait un profil entièrement conique, atteignent la surface plane et sont donc réfléchis parallèlement ; on augmente ainsi le rendement optique du dispositif;
• la source lumineuse est agencée à distance de la tranche d'entrée, les rayons lumineux émis étant guidés jusqu'à la face de réflexion en forme de secteur angulaire de cône d'axe de source afin de diriger les rayons lumineux radialement exclusivement vers la tranche de réflexion de la nappe de guidage.

generally parallel to the optical axis, the outgoing beam of each streak will be centered on an axis parallel to the optical axis;

• said output wafer is generally flat, the reflection wafer having at least one parabolic shape whose director forms an angle with the normal to the output wafer such that the light rays are generally parallel or parallel to the optical axis once refracted by said output slice; in the absence of streaks on the output wafer, the light rays refracted by the output wafer will be parallel to the optical axis; in the presence of streaks horizontally spreading the light, the light rays refracted by the output wafer will be generally parallel to the optical axis, the beam emerging from each streak will be centered on an axis parallel to the optical axis;
• the output wafer is curved, the reflection wafer having a complex shape such that for any point of the output wafer, any ray reflected by the reflection wafer arriving at this point of the output wafer is refracted parallel to the axis optical;
• the output wafer comprises means for defining the opening of the light beam in a plane tangential to the guide ply;
• the output wafer has ridges which are capable of deflecting the light rays coming out by refraction in a plane tangential to the guide ply;
• the guide web has holes which are arranged near the exit edge, the light rays being deflected from their path in a tangential plane through the wall of the hole before entering the guide web again in the direction of the edge. Release ;
• the holes are aligned in a quincunx parallel to the output wafer;
• the input portion of the light rays comprises a front portion which is shaped so as to disperse the light rays coming from the light source going directly towards the output wafer;
• the light source is a radial emission LED and the guide sheet comprises an orifice having a peripheral wafer which corresponds to said input wafer, said radial emission LED being placed inside said orifice;
• the light source is an axial emission LED and the guide sheet comprises a reflection surface corresponding to a shape complementary to a cone whose axis of symmetry corresponds to the source axis of the light source, this reflection surface being arranged opposite the input wafer to direct the light rays radially into the guide wrap;
• preferably the complementary surface comprises a part with a conical profile and a flat part, the part with the conical profile being surrounded by said reflection slice and said flat part being oriented opposite the outlet slice so that the rays emitted at the plane portion are reflected parallel to a preferred direction, for example the optical axis; thus, all the rays arriving on the conical profile shape are reflected towards the reflection slice, while those which could not reach this slice of reflection if the complementary surface had a completely conical profile, reach the plane surface and are therefore reflect in parallel; the optical efficiency of the device is thus increased;
• the light source is arranged at a distance from the input wafer, the light rays emitted being guided to the reflection face in the form of angular sector of the source axis cone in order to direct the light rays radially exclusively towards the wafer reflection of the guide web.

• la figure 1 est une vue de face qui représente un dispositif d'éclairage selon l'invention comportant une nappe de guidage ;
• la figure 2 est une vue de détail à plus grande échelle de l'agencement d'une source lumineuse dans la nappe de guidage de la figure 1 ;
• la figure 3 est une vue de dessous de la nappe de guidage de la figure 1 ;
• la figure 4 est une vue de côté qui représente une variante de la source lumineuse de la figure 2 ;
• la figure 5 est une vue en section selon le plan de coupe 5-5 de la figure 3 ;
• la figure 6 est une vue similaire à celle de la figure 5 qui représente une variante de réalisation de l'invention ;
• la figure 7 est une vue en perspective qui représente un dispositif d'éclairage qui comporte une pluralité de nappes de guidage qui sont agencées sur une sphère de base et dans lequel les tranches de sorties des nappes de guidage comportent des stries ;
• la figure 8 est de détail en perspective qui représente une variante de réalisation des nappes de guidage de la figure 7 ;
• la figure 9 est une vue de face qui représente un agencement de plusieurs nappes de guidage en strates ;
• la figure 10 est une vue de dessus d'un dispositif d'éclairage selon l'invention comportant une nappe de guidage plane ;
• la figure 11 est une vue en section de détail à plus grande échelle de l'agencement d'une source lumineuse dans la nappe de guidage de la figure 1 ;
• la figure 12 est une vue en section de détail de l'agencement d'une source lumineuse avec la nappe de guidage selon une variante de réalisation ;
• la figure 13 est une vue en section de détail de l'agencement d'une source lumineuse avec la nappe de guidage selon une autre variante de réalisation ;

Other characteristics and advantages will become apparent on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings among which:

• the figure 1 is a front view which shows a lighting device according to the invention comprising a guide sheet;
• the figure 2 is a detail view on a larger scale of the arrangement of a light source in the guide ply of the figure 1 ;
• the figure 3 is a bottom view of the guide web of the figure 1 ;
• the figure 4 is a side view that represents a variant of the light source of the figure 2 ;
• the figure 5 is a sectional view along the sectional plane 5-5 of the figure 3 ;
• the figure 6 is a view similar to that of the figure 5 which represents an alternative embodiment of the invention;
• the figure 7 is a perspective view which shows a lighting device which comprises a plurality of guide webs which are arranged on a base sphere and in which the output slices of the guide webs comprise streaks;
• the figure 8 is in perspective detail which represents an alternative embodiment of the guide plies of the figure 7 ;
• the figure 9 is a front view showing an arrangement of a plurality of stratum guide webs;
• the figure 10 is a top view of a lighting device according to the invention comprising a flat guide ply;
• the figure 11 is an enlarged sectional detail view of the arrangement of a light source in the guide web of the figure 1 ;
• the figure 12 is a detail sectional view of the arrangement of a light source with the guide web according to an alternative embodiment;
• the figure 13 is a detail sectional view of the arrangement of a light source with the guide web according to another embodiment;

Subsequently, identical, similar or similar elements will be designated by the same reference numbers.

For the remainder of the description, a fixed longitudinal orientation with respect to the motor vehicle will be adopted without limitation. directed from back to front which is indicated by the arrow "L" of Figures 1 and 2 .

We have shown figure 1 a lighting or signaling device 10 for a motor vehicle. The lighting device 10 is capable of emitting a linear light beam "F" along a generally longitudinal optical axis "A".

The lighting device 10 comprises in particular at least one light guiding ply 12 which is in the form of a spherical cap portion. The lighting device 10 shown in FIG. figure 1 comprises a single guide ply 12 forming a portion of an imaginary base sphere 13.

For the rest of the description, a normal orientation "N" orthogonal to the guide ply will be adopted locally at all points of the guide ply 12, and without limitation.

The guide ply 12 is thus delimited in the direction of the thickness, by a front face 14 and a rear face 16 for guiding the light. The two front 14 and rear 16 faces are parallel to each other on at least a portion of the web.

The guide ply 12 is in particular delimited laterally by a front edge of exit 18 from the light rays and by a rear reflection slice of the light 20. In the example shown in FIG. figure 1 the ends of the reflection slice 20 are directly connected to the end of the outlet slice 18 so as to form the outer contour of the guide ply 12.

The reflection slice 20 may be constituted by a reflective layer, such as an aluminized coating on the outer face of the reflection slice 20. It can also be provided that between the two junctions between the reflection slice 20 and each of the faces 14 and 16 of the guide web 12, the output wafer 18 has a stop extending along this wafer and separating it into two faces forming an angle between it. Thus an incident ray RI will undergo a double reflection, a first on one of the faces and a second on the other face, to be emitted in the plane of propagation reflected "Mr".

The outline of the light output wafer 18 here forms a plane arc, that is, the edge of the output wafer is defined by the intersection of the base sphere 13 and a plane.

According to a variant of the invention shown in figure 7 , the outer contour of the guide ply 12 also comprises inactive transition zones 22 which are interposed between the reflection slice 20 and the outlet slice 18.

As represented in figure 2 , the guide ply 12 also comprises an orifice 24 which is delimited by a peripheral edge 26 of the entrance of the light. The orifice 24 is here through. A light source 28 is arranged in the orifice 24 near or in contact with the input section of the light beams 26.

The light source 28 is capable of emitting light rays in a generally radial direction around a source axis "S" which is normal to the guide ply 12. More precisely, the light source 28 is capable of emitting a a range of light rays radially at least rearward towards the reflection slice 20.

The light source 28 is here a light emitting diode or "LED" called "Side-Emitter" which emits light rays in a range for example about 30 ° on either side of the radial direction in a meridian plane to the source axis "S" and which is likely to extend around the source axis "S", for example 360 ° in a plane normal to the source axis "S".

As represented in figure 11 , the "side emitter" type LED, also called lateral emitting LED is arranged is arranged so that its emitting surface is in a through opening arranged in a coupling zone "ZC" with the light source 28. Radiation r emitted radially by the LED are shown and all go into the thickness of the coupling area "ZC". The emission cone C of the LED is also schematically represented, it corresponds approximately to the level of the input slice to the thickness of the guide ply. Thus the coupling zone "ZC" allows a coupling between the guide layer 12 and the light source 28, so that the radii light emitted by said light source are propagated radially at said coupling area around a source axis "S".

According to variants represented in Figures 12 and 13 , the orifice is opening only in one of the guide faces of the guide ply 12 but not in the other of the faces. So in figure 12 , the source 28 is here a Lambertian type LED, or LED axial emission. Here, it is - a LED devoid of a dome, for example an LED available under the trade name "Golden Dragon" -. It emits in a half space. It is arranged so that its emitting surface is flush with the surface of the coupling zone "ZC" which has been arranged in such a way that the light rays emitted by the light source are then redirected radially at the level of the said zone. coupling around a source axis "S". The coupling zone "ZC" locally has an inlet zone in the form of a convex convex surface "B" on the side of which the LED 28 is located, and on the opposite face and opposite this convex face. "B", an area approaching the shape of a shape complementary to a cone "CO". We can distinguish two types of light rays emitted by this LED: the r1-type rays that enter directly into the thickness of the coupling zone, and r2-type rays that are first refracted by the surface B and then reflected totally by the cone walls "CO." The emission cone "C" of the LED is also shown.

According to the variant represented in figure 13 this time, a lambertian-type LED with a protective dome is used. Such a LED is for example known under the trade name "Led Rebel". The LED 28 is disposed in the coupling zone "ZC" so that the dome is inserted into a non-through opening provided in the coupling zone. In this opening there is a convex curved surface "B" and on the opposite face of the coupling zone a fitted surface of a zone approaching the shape of a shape complementary to a "CO" cone, so that as at the figure 12 the rays that reach it go back into the coupling zone "ZC" by total reflection. So we find, as in the figure 12 , two types of rays emitted by the LED: those of type r1 emitted towards the sides which enter directly into the coupling zone, and those of type r2 which are first refracted on the surface B and then reflected completely on the modified surface located next to surface B.

The cone "CO" may also have a deformed area to return the rays that without this area would directly reach the edge of output. This is for example a kind of "truncation" so that the reflection zone "CO" has a flat face. Thus according to a section along a plane perpendicular to the source axis "S" and approximately at the face of the guide ply which is opposite the LED 28, the periphery of the cone corresponds to a circle. With the truncation we obtain a section in the form of a circle in which an arc of circle would have been removed, a line connecting the two ends of the part of the remaining circle. We thus obtain a flattened circle. This line forms the base of the triangle formed by the truncation on the cone. The top of this triangle opposite this base is located on the cone between the two faces of the guide ply, preferably near the top of the cone. We thus obtain a cone with a flattened face. This flattened face is located next to the exit slice. All the rays emitted above the conical section portion will therefore be distributed around the source axis "S" within an angular interval corresponding to the circular portion of the cone section on the face opposite the LED 28. Preferably the top of the flat face is located between the top of the cone and the base thereof, the side of the exit edge (eg left on the Figures 12 and 13 ). Thus the angular interval is greater than 180 °. The reflection slice surrounds this zone conical profile and thus the set of rays reflected around the source axis "S" is reflected a second time by the reflection slice. On the other hand, the rays emitted above the plane face will be reflected in the same direction and directly towards the output edge, the base of the triangle constituting the plane face perpendicular to the optical axis.

In conclusion on the choice of LEDs, it can be seen that the invention makes it possible to use LEDs with very different characteristics, which can emit either radially, axially or in a half-plane. It is then necessary to arrange the coupling zone accordingly, for example by making an opening therethrough or not to insert all or part of the LED, and providing optical means when necessary (especially for the LEDs emitting in half a plane) so that the maximum of the light emitted by the LED propagates well in the thickness of the coupling zone without loss to the rear reflection zone 20.

In the examples shown, the entrance wafer of the light 26 is thus surrounded by the outer contour including the exit wafer 18 and the reflection wafer 20 of the guide wafer 12. However, the input wafer 26 can not not be closed. Indeed, there is a sector of this slice 26 inefficient, located vis-à-vis the reflection slice 20, and for which the rays reflected by the slice 20 return to the input slice 26. These light rays are not used in the lighting or signaling device, they are lost. We can take advantage of this observation to not have material in this region, to facilitate the demolding of the guide web.

The guide sheet 12 is made of a transparent material whose refractive index is greater than the refractive index of the medium in which the lighting device 10 is intended to be immersed, for example air. Thus, a light ray introduced into the thickness of the ply 12 by its input slice 26 with an incident angle relative to the normal "N" which is greater than a limit angle of refraction is likely to be reflected totally by the guide faces 14, 16.

The light ray is thus guided in the thickness of the guide sheet by successive reflections between the two guide faces 14, 16.

As represented in figure 3 , the incident light rays that go backwards are intended to be reflected by the reflection slice 20, then the light rays thus reflected are directed towards the output wafer 18. The reflected light rays thus come out of the output wafer 18 tangentially to the guide ply 12 to form the linear "F" light beam in an arc.

For the remainder of the description, an incident light ray will be defined as a light ray which is emitted by the light source 28 in the direction of the reflection slice 20. The light rays emitted by the light source 28 directly towards the slice of light output 18 are therefore not included in this definition of incident rays. The light rays that are emitted forward by the source Luminous 28 directly towards the output slot 18 will be called "direct".

The light source 28 may also consist of an incandescent lamp, for example a halogen lamp, with an axial filament, inserted in the contour delimited by the entrance wafer 26. It will then be advantageous to provide in this case for a zone the guide ply, in the vicinity of the entrance slice 26, is made of glass, while the rest of the ply will be made of plastic material overmoulded on this glass area. Such a design makes it possible to overcome the thermal problems that could generate the use of an incandescent source.

To prevent the input slice 26 from being visible by an observer located in the axis A, or more precisely to prevent this observer from seeing a light spot, corresponding to the light source, surrounded by two black dots, corresponding to the faces upper and lower the input wafer 26, it is advantageous to ensure that each point of the portion of the input wafer 26 corresponding to the direct rays returns light to a given area of the output wafer.

For example, it will be possible to give a complex shape 29 to the input wafer 26, in such a way that the light rays are collimated in the plane tangent to the ply, so that these rays of light reach a reduced zone of the output wafer 18. The addition of streaks on this complex shape 29 then makes it possible to optimize the concentration of the rays reaching the zone of the output wafer 18, and consequently also the size of this zone of the output wafer 18, so that this zone n 'appears no brighter than the rest of the contour for an observer in the axis.

The input-oriented slice portion 26 is thus shaped to distribute the direct light rays substantially uniformly along the output wafer 18. As shown in FIG. figure 2 , the front portion 29 of the input wafer 26 is striated so as to disperse the light rays in a fan that covers at least the entire output wafer 18.

So that the direct light rays are collimated in the plane tangent to the web, it is also possible to place on the zone of the input slice corresponding to the direct rays, in front of the LED with respect to the optical axis, a zone of the shape of a curved convex surface, facing the LED 28, the surface being curved in the direction of the LED. For example, the convex zone can be put in place of the striated zone 29 represented in figure 2 . According to an alternative embodiment, represented on the figure 10 , the orifice inside which the LED 28 is placed, has a shape such that it presents on the one hand a concave shape, on the back of the LED 28 with respect to the optical axis "A" of the lighting device and whose section is preferably a semicircle, and secondly a convex convex shape at the front of the LED. The concave shape and the convex shape are separated by a flat portion, allowing the light source to be positioned closer to the concave shape at the rear than the convex shape at the front. This removes the convex shape of the source and thus reduces the section of the cone of direct rays reaching the convex form. Part of the rays will thus reach the flat part and will be refracted in the direction of the reflection face. This increases the amount of reflected rays. It should be noted that for the sake of clarity, only the orifice is represented in figure 10 ; the LED 28 is not shown but its reference indicates its position within the orifice.

Likewise, it may be provided that the entrance slice 26 is slightly frustoconical, so as to optimize the mean direction of the rays in the ply in the meridian plane relative to the tangent to the ply.

According to a variant represented in figure 4 , the light source 28 is arranged near the input wafer 26. The light source 28 is associated with a reflection face 30 which is arranged vis-à-vis the input wafer of the light rays. The reflection face 30 is shaped so as to reflect the light rays generally radially towards the entrance edge 26 of the guide ply 12. The light rays coming from the light source 28 are, for example, ducted to the reflection face. 30 by a guide of 32, by an optical fiber (not shown), or by a reflector (not shown) which focuses the light rays towards the reflection face 30.

The light source 28 is for example a halogen lamp or a light emitting diode.

In the example shown in figure 4 the light rays are guided so as to reach the reflection face 30 generally along the source axis "S". The reflection face 30 is shaped into a cone of revolution or a cone of revolution portion of source axis "S" so as to reflect the radially radially around the source axis "S".

Advantageously, the reflection face 30 is shaped in a rear portion of the cone so as not to produce "direct" light rays but only "incident" light rays.

Advantageously, the reflection face 30 forms an upper end face of the light guide 32 and the light guide 32 is integrally formed with the guide ply 12.

According to the teachings of the invention, the guide ply 12 is designed so that the incident light rays emitted backwards by the light source 28 propagate in the guide ply 12 according to meridian plans "Mi" propagation said "incidents" radiating radially from the source axis "S". Thus, each light beam is guided so as to follow a radial direction inside the guide sheet 12 to the reflection slice 20.

In addition, the guide ply 12 is also designed so that the rays reflected by the reflection slice 20 propagate forwardly according to so-called "reflected" planar planes which are normal to the guide ply 12 between the reflection slice 20 and the output slice 18. The reflection slice 20 is more particularly shaped so that the reflected propagation planes "Mr" are oriented parallel to the optical axis "A".

Thus, the reflected light rays are distributed parallel throughout the output wafer 18 so that each point of the output wafer emits a substantially equal amount of light in the direction of the optical axis A. In this manner, the output wafer is homogeneously viewed for an observer viewing the output contour in the A-axis.

Advantageously, but in a nonlimiting manner, the reflected propagation planes "Mr" are orthogonal to the output wafer 20 so that all of the reflected light rays that reach the output wafer 20 exit without loss of light intensity.

The reflection slice 20 is here perpendicular to the guide faces 14, 16 of the guide ply 12.

This design is made possible firstly by the shape of the base sphere portion 13 of at least one rear portion 12R of the guide sheet which is traversed by the incident light rays between the light source 28 and the reflection slice 20, and on the other hand by the particular shape given to the contour of the reflection slice 20.

The rear portion 12R forms at least one angular sector extending from the source axis "S" and which envelopes the reflection slice 20.

Due to the curved shape of the base portion 13 of the rear portion 12R of the guide ply 12, the reflected propagation planes "Mr" are intersecting along the same axis which passes through the center "O" of the base sphere and which is confused with the optical axis "A". In addition, the source axis "S" is intersecting with the optical axis "A" at the center "O" of the base sphere.

• "O" étant le centre de la sphère de base de la portion arrière de la nappe de guidage 12 ;
• "M" étant un point quelconque de la tranche de réflexion 20 ;
• dOM étant la différentielle du vecteur OM, c'est-à-dire la tangente en M au contour de la tranche de réflexion 20 ;
• u_i étant un vecteur unitaire orthogonal au plan méridien incident "Mi" passant par le point "M" ;
• u_r étant un vecteur unitaire orthogonal au plan de propagation réfléchi "Mr" passant par le point "M".

Moreover, the contour of the reflection slice 20 is mathematically defined by the following equation: $$\overrightarrow{\mathit{dOM}}\wedge \left(\overrightarrow{u_i}-\overrightarrow{u_r}\right)=\overrightarrow{0}$$

• "O" being the center of the base sphere of the rear portion of the guide ply 12;
• "M" being any point on reflection slice 20;
• dOM being the differential of the vector OM, that is to say the tangent in M to the contour of the reflection slice 20;
• u _i being a unit vector orthogonal to the incident meridional plane "Mi" passing through the point "M";
• u _r being a unit vector orthogonal to the reflected propagation plane "Mr" passing through the point "M".

This equation reflects the fact that the image of an incident propagation plane "Mi" by the reflection slice 20 is a "Mr" propagation plane.

This differential equation can be solved either by analytical means or numerically using a calculator.

When the radius of the base sphere 13 tends to infinity, the guide web 12 can be considered flat. The reflection slice 20 then has the shape of a parabola and the reflected propagation planes "Mr" are parallel to each other.

However, when the radius of the base sphere 13 is finite, the shape of the reflection slice can not be likened to a parabola.

The guide plies 12 shown in the figures here are portions of spherical caps.

According to a not shown variant of the invention, the guide ply 12 has a more complex shape. To respect the conditions described above, however, it is essential that a rear portion 12R of the guide ply 12 forms a portion of the base sphere.

On the other hand, while respecting the condition according to which the reflected propagation plane "Mr" is intersecting along the optical axis "A" and orthogonal to the guide ply 12, the other front portion 12F of the guide ply 12 which is traversed only by reflected rays can have various forms. To do this, the guide faces 14, 16 form surfaces of revolution about the optical axis "A" passing through the center "O" of the base sphere 13.

The radii of curvature of the section of the guide ply 12 according to the reflected propagation plane "Mr" are advantageously large enough to prevent incident light rays do not reach one of the guide faces 14, 16 with an angle greater than the limit angle of refraction and exit the guide ply 12 before reaching the outlet edge 18.

For example, the guide ply 12 may have a front portion of flared shape.

According to another aspect of the invention, as a function of the characteristics of the light beam "F" that it is desired to obtain, the guide ply 12 is completed by known optical systems for focusing or, on the contrary, spreading the light rays forming the light beam "F" in a meridian plane and / or in a plane tangential to the guide web 12.

For this purpose, the output edge 18 of the guide ply is here shaped as a linear lens.

The output wafer 18 is for example inclined with respect to a direction normal to the ply 12 as represented in FIG. figure 5 . Thus, the outgoing light rays are deflected by refraction so as to diverge or otherwise be focused parallel to the optical axis "A".

According to a variant represented in figure 6 , the sheet 12 flares near the outlet edge 18, which is itself curved here, so as to focus the light rays in the reflected propagation plane "Mr".

As represented in figure 7 the outlet wafer 18 may also be provided with radial striations 34 so as to spread the light in a plane tangential to the guide ply 12 so that the light beam "F" is visible to an observer who is situated at an angle to to the optical axis "A".

According to a variant of the invention which is represented at figure 8 , the ridges 34 are replaced by holes 36 which are formed in the guide ply 12 near the outlet edge 18. The holes 36 are here aligned in parallel with the staggered exit slice 18. The contour of the holes is realized in such a way that the reflected rays are deflected divergently diverging into the hole 36 before re-entering the guide web 12 in the direction of the The staggered arrangement of the holes 36 makes it possible to avoid any escape through which reflected rays would reach the outlet edge 18 without passing through a hole 36.

According to another aspect of the invention, as shown in figure 7 a plurality of guide plies 12 forming portions of a common base sphere 13 may be arranged so as to obtain a set of light beams forming a single closed annular beam or an open circular arc.

The contour of the output wafer 18 is then defined as the intersection between the base sphere and a plane perpendicular to the optical axis "A".

According to a variant of the invention shown in figure 9 , the guide plies are arranged in a first spherical inner layer of four guide plies 12 which are portions of a first common base sphere and in a second spherical outer layer of three guide plies 12 which are portions of a second common base sphere. All the guide plies 12 are centered on a common center "O". Thus, two concentric annular beams can be obtained with a lighting or signaling device 10 of reduced size. The guide plies 12 of the two layers are staggered so that the light sources 28 are angularly offset relative to each other about the optical axis "A".

According to a variant not shown of the invention, it is also possible to obtain a light beam "F" of non-circular shape through guiding layers are the output edge 18 is not in the form of a circular arc plan. Thus, the contour of the output slices 18 is obtained by the intersection between a base sphere and any surface.

For example, it is possible to arrange a plurality of guide plies which have different axes and different radii of curvature, for example to make any contour consisting of several arc of circles.

For example, to obtain a light beam "F" forming an elliptical ring, the contour of the exit slices 18 is obtained by the intersection between the base sphere 13 and a cylindrical surface of revolution. The output slices 18 then have a left contour, that is to say that is not plane. The light rays must therefore be redirected, for example by streaks 34, at their output from the guide ply 12 in order to be directed in the overall direction of the optical axis "A".

With the lighting or signaling device 10 according to the invention, the light rays from the light source 24 reach the output wafer 18 without losing their intensity. This design therefore makes it possible to obtain a light beam "F" of linear shape, here in the shape of an arc of a circle.

Such a lighting or signaling device 10 has a good efficiency, that is to say that the intensity of the emitted light beam "F" is only slightly less than the intensity of the light source 24. For example , the light beam "F" may have an intensity of 600 Cd for a light source with a luminous flux of 25 Lm.

In general, it will be understood that the rear portion 12R of the guide ply 12 is advantageously a base sphere portion in order to optimize the intensity of the light beam as much as possible.

However, the invention is also applicable to guide plies which have a basic ellipsoid portion shape which differs little from a base sphere so that the light rays deviate slightly from the "Mr" propagation planes and / or or "Mi" without the intensity of the light beam being significantly degraded. This is particularly the case for ellipsoids whose diameters have relatively similar dimensions.

The invention also relates to flat sheets, such as for example that represented in figure 10 , where the conformation of the reflection slice 20 is determined according to the shape and / or the orientation of the output slice 18, so that any incident ray "RI" emitted by the light source 28, is reflected by the reflection slice 20 into a reflected ray "RR" included in a plane reflection reflection normal to the guide ply and making a given angle with the exit face 18, such that this ray is refracted by the exit face 18 into a light ray "RS" coming out of the ply parallel to the optical axis "AT".

According to figure 10 , the output wafer 18 is substantially rectilinear and not perpendicular to the optical axis "A", thus forming a determined angle with the normal to this optical axis. For radii exiting "RS" parallel to the optical axis, the angle between these outgoing radii and the normal "N" at the output wafer 18 is equal to that between the optical axis "A" and this same normal "NOT". The index of refraction of the sheet is known and that of the medium in which the outgoing ray "RS" circulates also. A direct relation, such as a Descartes relation, thus makes it possible to obtain the angle of the reflected rays "RR" with the normal "N" at the output wafer 18, hereinafter called "parallel refraction angle". The reflection slice 20 is formed of three parabolas, with a light source 28 disposed at each of their focus. The reflected rays "RR" are therefore included in reflected propagation planes parallel to the "D" direction of the parabolas. Thus, by choosing an orientation of the reflection slice 20 so that the "D" direction of the parabolas is at an angle with the normal to the output slice 18 which corresponds to the parallel refraction angle, the incident rays " RI "will be reflected by the reflection slice 20, reflected rays" RR ", which will themselves be refracted by the output slice 18 outgoing radii" RS "parallel to the optical axis" A ".

Three parables have been represented but this is not limiting. We can indeed predict less or more. By using more parabolas and limiting them to the side, the distance from the focus of the dish to the output wafer is decreased, thus allowing the use of shallower guidewires.

According to an alternative embodiment not shown, the output wafer may have a non-rectilinear shape, for example curved. Under these conditions the shape of the reflection slice will have a complex shape, that is to say a distinct form of a parabola, an ellipse or other simple geometric shapes. For each portion of the At the output, a positioning and orientation of the reflection slice is determined such that the angle of the reflected ray "RR" is refracted to an outgoing radius "RS" parallel to the optical axis "A".

It is possible to place streaks on the output edge, regardless of the contour of the output curve. These are streaks or holes 36 as previously defined, in order to homogenize the distribution of the light intensity on the output wafer. In addition, the rays emerging from each streak will be distributed laterally but centered around the optical axis A.

According to another variant embodiment, the output wafer is perpendicular to the optical axis, the reflection wafer forming at least one parabola according to the plane of the guide layer and whose director is parallel to this optical axis. The reflected rays are then included in reflected propagation planes parallel to the optical axis. The output wafer is preferably provided with ridges or holes 36 as previously defined, in order to homogenize the distribution of the light intensity on the output wafer. The rays issuing from each streak will be distributed laterally but centered around the optical axis A.

Claims (18)

1. Lighting or signalling device (10) for a motor vehicle, which can emit a linear beam (F) globally according to the direction of an optical axis (A), and which comprises:

   - a source of light (28);

   - a sheet (12) for guiding of the rays of light, which comprises an input section (26) for the rays of light, a front section (18) for output of the rays of light tangentially to the guide sheet (12), and a rear sheet (20) for reflection of the rays of light obtained from the source of light (28) in the direction of the output section (18),

   characterised in that the guide sheet (12) has a curved form, and in that the guide sheet (12) comprises an area (ZC) of coupling with the source of light (28), which is formed such that the rays of light emitted by the said source of light are propagated radially at the level of the said area of coupling, around a source axis (S), in that the guide sheet (12) is formed such that the rays of light are propagated on incident meridian propagation planes (Mi) which are normal to the sheet (12), between the source of light (28) and the reflection section (20), on reflected propagation planes (Mr) which are normal to the sheet (12), between the reflection section (20) and the output section (18), and in that the reflection section (20) is formed such that the reflected propagation planes (Mr) have orientation relative to the optical axis (A) such that the said lighting device (10) can emit a linear light beam (F) according to a globally longitudinal optical axis (A).
2. Device (10) according to the preceding claim, characterised in that the reflected propagation planes (Mr) are parallel to the optical axis (A) of the lighting device (10).
3. Device (10) according to either of the preceding claims, characterised in that the reflected propagation planes (Mr) are at right angles to the output section (18).
4. Device (10) according to any one of the preceding claims, characterised in that at least a first rear portion (12R) of the guide sheet (12) delimited by an angular sector which extends from the source axis (S) and envelops the reflection section (20) has the form of a portion of a base sphere (13).
5. Device (10) according to the preceding claim, characterised in that the source axis (S) passes via the centre (O) of the base sphere (13).
6. Device (10) according to the preceding claim, characterised in that a second front portion (12F) of the guide sheet (12) forms a solid of revolution around the optical axis (A) which passes via the centre (O) of the base sphere (13).
7. Device (10) according to claim 5 or 6, characterised in that the reflected propagation planes (Mr) intersect according to the optical axis (A).
8. Device (10) according to any one of the preceding claims, characterised in that at least two guide sheets (12) are arranged on a first layer, at least a third guide sheet (12) being arranged on a second layer, each guide sheet (12) being a portion of a base sphere.
9. Device (10) according to the preceding claim, characterised in that the guide sheets (12) of the first layer are portions of a first common base sphere, and in that the guide sheets (12) of the second layer are portions of a second common base sphere, all the guide sheets (12) being centred on a common axis (O).
10. Device (10) according to claim 8, characterised in that the guide sheets (12) have different axes and different radii of curvature.
11. Device (10) according to any one of the preceding claims, characterised in that the output section (18) of the rays of light comprises means for defining the opening of the light beam around the direction of the optical axis (A) on the reflected propagation plane (Mr).
12. Device (10) according to any one of the preceding claims, characterised in that the output section comprises means (34, 36) for defining the opening of the light beam on a plane which is tangent to the guide sheet (12).
13. Device (10) according to the preceding claim, characterised in that the output section (18) comprises striations (34) which can deflect the rays of light which emerge by refraction on a plane tangential to the guide sheet (12).
14. Device (10) according to claim 12, characterised in that the guide sheet (12) comprises holes (36) which are arranged in the vicinity of the output edge, the rays of light being deflected from their trajectory on a tangential plane and passing through the wall of the hole (36) before returning once more to the guide sheet (12) in the direction of the output section (18).
15. Device (10) according to any one of the preceding claims, characterised in that the input section (26) of the rays of light comprises a front portion (29) which is formed such as to disperse the rays of light obtained from the source of light (28) facing directly towards the output section (18).
16. Device (10) according to any one of the preceding claims, characterised in that the source of light (28) is an LED with radial emission, and the guide sheet (12) comprises an orifice (24) with a peripheral section which corresponds to the said input section (26), the said LED with radial emission being placed in the interior of the said orifice.
17. Device (10) according to any one of the preceding claims, characterised in that the source of light (28) is an LED with axial emission, and the guide sheet (12) comprises a reflection surface corresponding to a form complementary to a cone (CO), and being arranged opposite the input section, in order to direct the rays of light radially in the guide sheet.
18. Device (10) according to the preceding claim, characterised in that the said complementary form comprises a part with a conical profile and a flat part, the part with the conical profile being surrounded by the said reflection section (20), and the said flat part being oriented opposite the output section (18), such that the rays which are emitted at the level of the flat part are reflected parallel to a preferential direction.

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