EP1605201B1 - Vehicle lighting or signaling device with a light guide - Google Patents

Abstract

The device has an optical light guide (5) including an output side (FS) to output light rays propagated in the guide, where the side (FS) has a profile including ridges. The guide has a reflecting side (FR) with an indented profile forming a light rays reflecting side. The reflecting side has a series of prisms (8), where facets of consecutive prisms form a truncated base angle (D).

Description

The present invention relates to a lighting and / or signaling device equipping a motor vehicle, comprising at least one optical guide capable of producing a homogeneous distribution of light. This optical guide includes prisms that allow to deflect the light rays.

The invention has applications in the field of vehicles traveling on roads and, in particular, motor vehicles.

• des dispositifs d'éclairage situés à l'avant du véhicule avec, notamment, des projecteurs de véhicules équipés de feux de croisement, ou codes, ayant une portée sur la route avoisinant 110 mètres, et de feux de route ayant une longue portée lumineuse et produisant une zone de vision sur la route avoisinant 200 mètres,
• des dispositifs d'éclairage situés à l'arrière du véhicule avec, notamment, les feux de recul,
• des dispositifs de signalisation situés à l'avant du véhicule avec, notamment, de feux de position, des indicateurs de direction et des D.R.L. (Daytime Running Light, en terme anglo-saxons) ou phares de jour (intégrés ou non aux projecteurs assumant les fonctions d'éclairage mentionnées plus haut), et
• des dispositifs de signalisation situés à l'arrière du véhicule avec, notamment, des feux antibrouillards, des feux arrière, des indicateurs de direction et des feux stop.

In the field of lighting and signaling of motor vehicles, various types of devices are known, among which we find essentially:

• lighting devices at the front of the vehicle including, inter alia, headlamps of vehicles equipped with low beam or code, with a range on the road of approximately 110 meters, and high beam with a long range of light and producing an area of vision on the road of about 200 meters,
• lighting devices at the rear of the vehicle including, in particular, the reversing lights,
• signaling devices located at the front of the vehicle with, in particular, position lights, direction indicators and DRLs (Daytime Running Light, in English term) or daytime headlights (integrated or not with the headlamps assuming the lighting functions mentioned above), and
• signaling devices at the rear of the vehicle including, but not limited to, fog lamps, taillights, direction indicators and brake lights.

Currently, it is known to use, in lighting devices or signaling devices, one or more optical guides for propagating a light beam. An example of a vehicle headlamp is described in the document US-A-6,107,916 . This projector has a light source and an optical guide, placed near the light source and propagating the light beam emitted by this light source. This light guide may run all or part of the mirror or reflector of the projector.

• une source lumineuse 3, émettant un faisceau lumineux dont la direction d'émission est représentée par une flèche 4, et
• un guide optique 5, propageant ledit faisceau lumineux 4.

An example of a projector is shown on the figure 1 . More specifically, the figure 1 schematically represents the left projector of a vehicle. This projector emits a light beam directed substantially towards the front of the vehicle, that is to say along the Y axis of the road. This projector 1 comprises a protective glass 2 forming the exit face of the projector 1. It also comprises:

• a light source 3, emitting a light beam whose emission direction is represented by an arrow 4, and
• an optical guide 5 propagating said light beam 4.

The optical guide 5 is a transparent material cylinder provided with prisms, which ensures the propagation of the light beam 4 from an end e1 close to the light source 3 to an end e2 opposite the end e1. This optical guide 5 can have different geometric shapes. It can, for example, form a circle, an arc or be straight. In the case of figure 1 , the optical guide 5 follows the shape of the protective glass 2 of the projector 1.

• une première face 6 constituant une face de sortie des rayons lumineux propagés dans le guide optique 5 ; cette face de sortie 6 est lisse et continue ; et
• une deuxième face 7, opposée à la première face 6 et constituant une face de réflexion du guide optique ; cette face de réflexion 7 a un profil dentelé, c'est-à-dire un profil en forme des dents de scie. Cette face de réflexion 7 comporte une succession de prismes 8 identiques et symétriques. Ces prismes 8, placés côte à côte, forment les dents scie de la face de réflexion 7.

An example of the optical guide 5 of this projector is shown in more detail on the figure 2 . This figure 2 shows a sectional view of the optical guide 5. This optical guide 5 has two faces:

• a first face 6 constituting an exit face of the light rays propagated in the optical guide 5; this exit face 6 is smooth and continuous; and
• a second face 7, opposite the first face 6 and constituting a reflection face of the optical guide; this reflection face 7 has a serrated profile, that is to say a profile in the form of saw teeth. This reflection face 7 comprises a succession of identical and symmetrical prisms 8. These prisms 8, placed side by side, form the saw teeth of the face of reflection 7.

On the figure 2 , the optical guide 5 is shown in a sectional view. For a better understanding of the figure, it is shown hatched on the figure 2 . So, according to the section view according to the figure 2 each prism 8 has a substantially triangular shape. More specifically, each prism 8 has a triangle shape with a base 14, a facet 9 and a facet 10, flat and non-parallel. These facets 9 and 10 form between them an angle A, called the angle of the prism. The facets 9 and 10 form, with the axis X of the optical guide 5, respectively, angles B and C. The facet 9 of a prism and the facet 10 of a consecutive prism together form a bottom angle D The bottom angle D of each prism is in contact with a curve called bottom line 11. This bottom line 11 connects the vertex of all the angles D of the reflection face 6 of the optical guide 5. In other words, if it is considered that each prism 8 is a triangle, in its section, the bottom line 11 connects the base 14 of each triangle with the base of the consecutive triangle.

It will be understood that the shape of each prism is considered triangular in a 2-dimensional view.

On the figure 2 FIGS. 12 and 13 show an example of a trajectory of a light ray propagating in an optical guide of the type described in the document. US-A-6,107,916 . This light ray may be one of the light rays contained in the light beam 4 emitted by the light source 3. In this example, the light beam propagates in the optical guide 5 in a straight initial trajectory 12 until he meets a facet of a prism. This trajectory 12 forms, with the axis X of the optical guide 5, an angle of incidence E. When a light ray encounters a facet of a prism, for example the facet 10 of a prism 8, in the case of the figure 2 , the trajectory 12 of the light beam is deflected by an angle F with respect to the initial trajectory 12. The deflected trajectory of the light beam is referenced 13. The deflection angle F between the trajectory 12 and the trajectory 13 is variable because bound especially to angles of the prisms. Thus, the light ray is redirected, by the prisms 8 of the reflection face 7, towards the exit face 6 of the optical guide 5.

In the example of the figure 2 and as a simplification of this figure, the trajectory of a single light ray has been shown. It is understood that other light rays with other trajectories may propagate in the optical guide, these rays may have been reflected one or more times, by one or more prisms or the other face of the optical guide, before to reach a prism that redirects it to the exit face 6.

In the example of the figure 2 the deflection 13 of the light beam responds to the principle of total reflection in an optical guide. The principle of total reflection is an optical phenomenon that allows the transmission of light in an optical guide 5. When a light ray passes from one medium to another medium having a different refractive index, its direction is changed; it is the effect of refraction. For a certain angle of incidence, and if the index of the initial medium is greater than that of the final medium, the light ray 12 is no longer refracted, it is totally reflected: it is called total reflection.

So, if we consider again the figure 1 it is understood that the light beam 4 must be distributed over the entire length of the optical guide, that is to say between the end e1 and the end e2. However, part of the light beam 4 is lost, with constant prisms, because the flow that passes through the section decreases as it spreads. It is therefore understood that at the end e2 of the optical guide 5, the amount of light lost is greater than at the end e1, close to the light source 3. In other words, the light output is less than the end e2 that at the end e1 of the optical guide, which has the consequence that there is a natural decrease in the flow of light emitted along the optical guide. This decay is visible to anyone outside the vehicle.

Moreover, in the example of the figure 2 for an angle of incidence E between 0 and 5 degrees, the light beam undergoes total reflection. Thus, a light ray touching one of the facets 9 or 10 of the prism 8 is reflected to the exit face 6 of the optical guide 5, by the principle of total reflection.

In other words, the light rays arriving at an angle not parallel to the X axis of the guide and, in particular, when they form an angle of 0 to 5 ° with this axis, are redirected to the exit face 6 of the optical guide through prisms 8. The presence of the prisms 8 on the reflection face 7 of the optical guide 5 thus allows the light to come out in the right direction. By the principle of total reflection, the light beam is reflected towards the exit face of the optical guide. In particular, it is reflected with a direction substantially perpendicular to the axis X of the optical guide 5, that is to say along the normal N to the axis X. Another direction of reflection of the light ray can be obtained by modifying the angle B and / or the angle C of the prism. In this case, if we call G the angle between the ray leaving the optical guide and the normal N, then this angle G can only be positive. In other words, by modifying the slope of the prisms, it is possible to redirect the outgoing light rays so as to have a non-zero angle G.

However, in some cases, it is interesting to be able to send the light rays in a direction forming a negative angle G with the normal N. For example, in the case of the figure 1 it can be seen that the optical guide 5 follows the profile of the protective glass 2 of the headlamp 1. Therefore, the reflected light rays illuminate on the sides of the vehicle in a direction Z. As can be understood from the view of the figure 1 , the light beam 4 emitted by the light source 3 propagates in the optical guide 5 to its opposite end e2. Near this end e2, the light rays emitted perpendicularly to the axis of the optical guide light the road laterally, and are seen by any observer on the side of the road. Thus, at this end e2 of the optical guide 5, the angle between the optical guide 5 and the desired direction of light rays Y is not favorable. These light rays are lost, that is to say that they are reflected towards an uninteresting direction, which reduces the expected performance of the lighting or signaling device.

It is also known from the application for EP 0935 091 a light guide whose reflective face is provided with prisms whose width varies along the guide, and whose bottom corners are truncated.

It is also known from the demand for EP Patent 1,167,869 a light guide whose section changes and decreases according to the length of the guide and whose emitting light side is equipped with tries.

It is also known from the patent application WO 2004/042271 a light guide whose section changes according to the length of the guide and whose reflection face is provided with reflecting zones offset relative to each other.

The invention aims to overcome the disadvantages of the techniques described above. The object of the invention is in particular to improve the performance of the light guides, in particular to improve their visual appearance in the lit state and / or to obtain a greater flexibility in the choice of the angle of exit of the light rays. emitted by the light guide. Its purpose is thus to improve / better control the emission of light by lighting and / or signaling devices using light guides, in particular to improve the homogenization of the light distributed / emitted by these guides. .

According to a first embodiment, it firstly proposes an illumination and / or optical guide signaling device, in which the light is distributed in a uniform and homogeneous manner along the optical guide. For this, the invention proposes an optical guide having a reflection face provided with a succession of prisms, the angles between two consecutive prisms of the reflection face being, at least for some, truncated. Alternatively or cumulatively, the output face has a profile with streaks, configuration detailed below.

The term "prism" indicates that these are geometric shapes usually defined by plane faces, but it is also within the scope of the invention to consider pseudo-primes, similar to prisms, but one of which faces is for example curved, more or less pronounced.

The term "serrated profile" indicates that the face in question is not entirely flat, that it includes reliefs, including but not only prisms.

• une face, dite face de sortie du faisceau lumineux, et
• une autre face, dite face de réflexion, opposée à la face de sortie, ayant un profil dentelé formant une face de réflexion du faisceau lumineux et comportant une succession de prismes, chaque prisme formant, avec le prisme suivant, un angle de fond,

avec au moins un angle de fond de la face de réflexion qui est tronqué.More specifically, the invention relates firstly to a lighting or signaling device for a motor vehicle comprising at least one light source emitting a light beam and at least one optical guide in which the light beam propagates, said guide optical comprising

• a face, said output face of the light beam, and
• another face, said reflection face, opposite to the exit face, having a serrated profile forming a reflection face of the light beam and comprising a succession of prisms, each prism forming, with the following prism, a bottom angle,

with at least one bottom angle of the reflection face which is truncated.

• certains au moins des angles de fond de la face de réflexion comportent une zone tronquée, la dimension de la zone tronquée étant variable d'un angle à un autre. Une telle zone tronquée permet de moduler et de contrôler le rendement de chaque prisme, c'est-à-dire le flux sortant localement d'un prisme par rapport au flux total traversant la section du guide au niveau de ce prisme, et d'optimiser l'aspect homogène de la lumière émise par le guide optique tout au long de sa longueur.
• la dimension des zones tronquées diminue au fur et à mesure de l'éloignement de la source lumineuse ;
• la face de réflexion comporte à la fois des prismes à angle de fond tronqué et des prismes à angle de fond non tronqué ;
• selon une première variante, les prismes ont des pas variables et une hauteur constante, ce qui permet de moduler le rendement de chaque prisme tout en modulant l'effet visuel ;
• selon une seconde variante (associable à la précédente), les prismes ont un pas constant et des hauteurs variables, ce qui permet également de moduler le rendement de chaque prisme, avec une réalisation simple à mettre en ceuvre ;
• le pas des prismes a une dimension de l'ordre de 0,2 à 2 mm ;
• la hauteur des prismes est de l'ordre de 0,2 à 2 mm ;
• les prismes (ou au moins un de ceux-ci) de la face de réflexion sont symétriques. Ce mode de réalisation est préférable lorsque le dispositif comporte plusieurs sources lumineuses (notamment une à chaque extrémité du guide)
• les prismes (ou au moins un de ceux-ci) de la face de réflexion sont dissymétriques, ce qui permet un meilleur rendement des prismes, et est préférable également quand une seule source lumineuse est utilisée pour alimenter le guide,

According to this first embodiment, the invention may include one or more of the following features:

• at least some of the bottom angles of the reflection face comprise a truncated zone, the size of the truncated zone being variable from one angle to another. Such a truncated zone makes it possible to modulate and control the efficiency of each prism, that is to say the flux exiting locally from a prism with respect to the total flux passing through the section of the guide at this prism, and of optimize the homogeneous appearance of the light emitted by the light guide along its length.
• the size of the truncated areas decreases as the light source moves away;
• the reflection face comprises both truncated bottom-angle prisms and non-truncated bottom-angle prisms;
• according to a first variant, the prisms have variable steps and a constant height, which makes it possible to modulate the output of each prism while modulating the visual effect;
• according to a second variant (which can be associated with the previous one), the prisms have a constant pitch and variable heights, which also makes it possible to modulate the output of each prism, with a realization that is simple to implement;
• the pitch of the prisms has a dimension of the order of 0.2 to 2 mm;
• the height of the prisms is of the order of 0.2 to 2 mm;
• the prisms (or at least one of them) of the reflection face are symmetrical. This embodiment is preferable when the device comprises several light sources (in particular one at each end of the guide)
• the prisms (or at least one of them) of the reflection face are asymmetrical, which allows a better performance of the prisms, and is also preferable when a single light source is used to feed the guide,

According to a second embodiment, alternative or cumulative with the previous one, the invention proposes a lighting and / or signaling device in which the optical guide comprises a serrated profile reflection face and a striated profile exit face. Such an exit face has the advantage of straightening an additional angle the light rays reflected by the reflection face, so as to obtain light rays coming out of the optical guide with a negative angle relative to the normal to the X axis (the negative sign is understood in relation to the mean direction of propagation of the light in the guide)
, which offers a great flexibility in the choice of the exit angles of the light rays coming out of the optical guide.

• une face, dentelée, dite face de réflexion et comportant une succession de prismes, et
• une autre face, opposée à la première face, formant une face de sortie du faisceau lumineux,

telle que la face de sortie a un profil comportant des stries.More specifically, the invention according to this second embodiment relates to a lighting and / or vehicle signaling device comprising at least one light source emitting a light beam and an optical guide adapted to propagate said light beam, said optical guide comprising :

• a face, serrated, said reflection face and comprising a succession of prisms, and
• another face, opposite to the first face, forming an exit face of the light beam,

such that the exit face has a profile with streaks.

• chaque strie de la face de sortie est située en regard d'un prisme de la face de réflexion, ce qui permet de collecter les rayons intéressants qui ont été réfléchis par le prisme auquel elle est associée.
• les stries de la face de sortie ont chacune (pour au moins l'une d'entre elles au moins) une forme courbe, notamment en arc de cercle, ce qui permet de réaliser une déviation variable d'un rayon lumineux provenant d'un même prisme, ce qui crée un étalement des rayons lumineux, donc une homogénéisation de l'aspect allumé du guide optique dans toutes les directions.
• les stries (pour au moins l'une d'entre elles au moins) ont chacune une forme de prisme à facettes planes. Ce mode de réalisation est simple à mettre en oeuvre et permet, sur le plan optique, de privilégier une direction d'émission des rayons lumineux.
• chaque (au moins un des) prisme est symétrique. Ce mode de réalisation est préférable lorsque le dispositif comporte plusieurs sources lumineuses.
• chaque (au moins un des) prisme est dissymétrique, ce qui permet un meilleur rendement des prismes, le rendement étant à comprendre comme le flux lumineux sortant localement d'un prisme par rapport au flux total traversant la section du guide au niveau de ce prisme,
• les stries (pour au moins l'une d'entre elles au moins) comportent chacune une facette en arc de cercle et une facette plane. Ce mode de réalisation permet de cumuler les avantages des deux modes de réalisation précédents (forme en arc de cercle et forme de prisme). En outre, il permet de limiter les perturbations vis-à-vis des rayons qui continuent leur propagation dans le guide optique.
• les stries (pour au moins deux elles au moins) de la face de sortie sont contiguës.
• les stries (pour au moins deux elles au moins) de la face de sortie sont non contiguës.
• chaque strie ((pour au moins l'une d'entre elles au moins) comporte un angle de strie, par rapport à un axe du guide optique, de l'ordre de 1 à 30°, de préférence de 5 à 20°.
• dans le cas où les prismes de la face de sortie comportent chacun une première facette et une seconde facette, la seconde facette formant un angle de fond avec la première facette d'un prisme consécutif, certains au moins des prismes de la face de réflexion comportent un angle de fond tronqué. Un tel angle de fond tronqué permet de moduler et de contrôler le rendement de chaque prisme, c'est-à-dire le flux sortant localement d'un prisme par rapport au flux total traversant la section du prisme, et d'optimiser l'aspect homogène du guide optique.

Such a device makes it possible to deviate in a controlled manner the rays coming from the prisms. The lighting and / or signaling device according to the second embodiment of the invention may comprise one or more of the following characteristics:

• each streak of the exit face is located opposite a prism of the reflection face, which makes it possible to collect the interesting rays which have been reflected by the prism with which it is associated.
• the streaks of the exit face each have (for at least one of them at least) a curved shape, in particular in an arc of a circle, which makes it possible to achieve a variable deflection of a light ray coming from a same prism, which creates a spread of light rays, so a homogenization of the lit appearance of the optical guide in all directions.
• the streaks (for at least one of them at least) each have a flat-faceted prism shape. This embodiment is simple to implement and allows, optically, to favor a direction of emission of light rays.
• each (at least one) of the prism is symmetrical. This embodiment is preferable when the device comprises several light sources.
• each (at least one) of the prism is asymmetrical, which allows a better performance of the prisms, the output being to be understood as the luminous flux coming out locally of a prism with respect to the total flux passing through the section of the guide at the level of this prism ,
• the streaks (for at least one of them at least) each comprise an arcuate facet and a flat facet. This embodiment makes it possible to combine the advantages of the two previous embodiments (arcuate shape and prism shape). In addition, it makes it possible to limit the disturbances with respect to the rays which continue their propagation in the optical guide.
• the ridges (for at least two of them) of the exit face are contiguous.
• the ridges (for at least two of them) of the exit face are non-contiguous.
• each streak (for at least one of them at least) has a stripe angle, with respect to an axis of the optical guide, of the order of 1 to 30 °, preferably 5 to 20 °.
• in the case where the prisms of the exit face each comprise a first facet and a second facet, the second facet forming a bottom angle with the first facet of a consecutive prism, at least some of the prisms of the reflection face comprise a truncated bottom angle. Such a truncated bottom angle makes it possible to modulate and control the efficiency of each prism, that is to say the flux coming locally from a prism with respect to the total flux passing through the section of the prism, and to optimize the homogeneous appearance of the optical guide.

• les sources lumineuses peuvent être de type halogène, être des diodes électroluminescentes, ou tout autre lampe comme des lampes xénon par exemple,
• le dispositif d'éclairage ou de signalisation peut comporter au moins deux sources lumineuses placées chacune à une extrémité du guide optique (sources lumineuses standard de type halogène ou diodes électroluminescentes par exemple) : le guide optique peut alors propager la lumière à partir des deux extrémités, ce qui permet d'avoir des guides d lumière de grande longueur.
• le dispositif d'éclairage ou de signalisation peut comporter plusieurs guides optiques ayant une intersection commune, au moins une source lumineuse étant située à ce point d'intersection. on a alors un guide de lumière « ramifié », avec de préférence une source au niveau des ramifications, et éventuellement à au moins une des extrémités des branches d'un tel guide.

As well according to the first as according to the second realization:

• the light sources may be of halogen type, be light-emitting diodes, or any other lamp such as xenon lamps for example,
• the lighting or signaling device may comprise at least two light sources each placed at one end of the optical guide (standard halogen-type light sources or light-emitting diodes, for example): the optical guide may then propagate the light from both ends , which allows to have light guides of great length.
• the lighting or signaling device may comprise a plurality of optical guides having a common intersection, at least one light source being located at this point of intersection. then there is a branched light guide, preferably with a source at the branches, and possibly at least one end of the branches of such a guide.

• La figure 1, déjà décrite, représente un exemple de projecteur de véhicule muni d'un guide optique.
• La figure 2, déjà décrite, représente une vue en coupe d'un guide optique de l'art antérieur.
• La figure 3 représente une vue en coupe d'un exemple de guide optique à troncature, selon l'invention.
• La figure 4 représente une vue en coupe d'un premier mode de réalisation d'un guide optique à troncature variable selon l'invention.
• La figure 5 représente une vue en coupe d'un second mode de réalisation d'un guide optique à troncature variable selon l'invention.
• La figure 6 représente une vue en coupe d'un guide optique selon l'invention dans le cas où la face de sortie du guide est striée.
• La figure 7 représente un premier mode de réalisation d'un guide optique selon l'invention ;
• La figure 8 représente un second mode de réalisation d'un guide optique selon l'invention ;
• Les figures 9A et 9B représentent un troisième mode de réalisation d'un guide optique selon l'invention

The invention also relates to a motor vehicle equipped with at least one lighting or signaling device according to this first embodiment and / or this second embodiment of the invention, as well as the light guide itself.

• The figure 1 , already described, represents an example of a vehicle headlamp equipped with an optical guide.
• The figure 2 , already described, represents a sectional view of an optical guide of the prior art.
• The figure 3 represents a sectional view of an example of a truncation optical guide, according to the invention.
• The figure 4 represents a sectional view of a first embodiment of a variable truncation optical guide according to the invention.
• The figure 5 is a sectional view of a second embodiment of a variable truncation optical guide according to the invention.
• The figure 6 represents a sectional view of an optical guide according to the invention in the case where the exit face of the guide is serrated.
• The figure 7 represents a first embodiment of an optical guide according to the invention;
• The figure 8 represents a second embodiment of an optical guide according to the invention;
• The Figures 9A and 9B represent a third embodiment of an optical guide according to the invention

The Figures 1 to 5 relate more specifically to the invention according to the first embodiment.

The Figures 7 to 9 relate more specifically to the invention according to the second embodiment.

The figure 6 more specifically relates to the invention combining the first and second embodiments of the invention.

The invention will be described below with the aid of two examples, and in both cases relates to an illumination or signaling device with optical guide allowing a homogeneous and uniform distribution of the light. The device of the invention can be a projector like that of the figure 1 or a signaling device. Whether it is a projector or a signaling device, the optical guide has characteristics ensuring a homogeneous and uniform appearance to the light at the exit of the guide optical. In the remainder of the description, a projector will be described, it being understood that it may also be a signaling device.

According to the first embodiment, an example of an optical guide according to the invention, which can be mounted in a projector of the figure 1 , is represented on the figure 3 . In the example that will be described, the lighting device considered is a position light located in a projector at the front of a vehicle. Also, the optical guide, in this example, is curved and forms a circle or an arc. It is understood that the optical guide, according to the invention, may have other shapes such as, for example, rectilinear curve with one or more curvatures ....

This figure 3 shows a sectional view of an optical guide 5 for propagating a light beam emitted by the light source 3. In this embodiment, the optical guide 5 has a circular section; it is understood that it can also, in other embodiments, have an elliptical section, square, oval, square or even.

• une première face FS constituant une face de sortie des rayons lumineux propagés dans le guide optique 5 ; cette face de sortie 6 peut être lisse et continue, comme sur les figures 3 à 5 ou bien comporter des stries, comme montré ultérieurement sur la figure 6;
• une deuxième face FR, opposée à la première face FS, constituant une face de réflexion du guide optique 5 ; cette face de réflexion FR comporte une succession de prismes 8. Ces prismes 8 sont placés côte à côte et assurent une réflexion des rayons lumineux ayant un angle d'incidence non nul avec l'axe X du guide optique 5.

This optical guide 5 has two faces:

• a first face FS constituting an output face of the light rays propagated in the optical guide 5; this exit face 6 can be smooth and continuous, as on the Figures 3 to 5 or have streaks, as shown later on figure 6 ;
• a second face FR, opposite to the first face FS, constituting a reflection face of the optical guide 5; this reflection face FR comprises a succession of prisms 8. These prisms 8 are placed side by side and provide a reflection of the light rays having a non-zero incidence angle with the axis X of the optical guide 5.

According to a sectional view of the optical guide 5, each prism 8 has a substantially triangular shape; each prism comprises a base 14, a facet 9 and a facet 10, flat and non-parallel. The facet 9 and the facet 10 of a prism 8 may be symmetrical with respect to an axis T perpendicular to the axis X of the optical guide, that is to say that they have dimensions and angles B and C identical on both sides of the bisector T. It is said that the optical guide is symmetrical prisms. The facet 9 and the facet 10 may also be asymmetrical, that is, they have different dimensions and / or angles B and C. It is said that the optical guide is asymmetrical prisms.

The facet 10 of a prism 8 and the facet 9 of a consecutive prism together form a bottom angle D. According to the invention, the bottom angle D of a prism 8 is truncated. In other words, at least some of the bottom angles D have a truncated area. This truncated area of the bottom angle D forms a flat surface 16. A flat surface 16 is therefore a flat part of the bottom line curve 11 shown in dotted line on the figure 3 . In the example of the figure 3 the bottom line 11 coincides with the X axis of the optical guide 5.

Everything happens as if the space between two prisms 8 formed an air prism 15: there is then, in the invention, the air primer 15 of the "clipped" type. In this case, the clipping of the air prisms 15 is made according to a section of the vertices of said air prisms. This section is made along the curve of the bottom line 11.

As will be seen more precisely below, the flats 16 of the bottom angles D are preferably of geometric shape of the rectangle type. They can have different dimensions. These dimensions of the flats can vary from one optical guide to another. They can also be variable within the same optical guide. In this case, the flats 16 may have different dimensions for each bottom angle D associated with each prism. Some bottom angles D may also have no flat surface 16. In this case, the optical guide 5 comprises both bottom angles D with flats 16 and bottom corners D without flat, for example alternately. For example, the size of the flats can be chosen decreasingly from the end e1 towards the end e2 of the optical guide in order to propagate a maximum of light rays towards the end e2.

According to the invention, the bottom angle D between two prisms 8 is truncated, which allows a light ray to propagate in the optical guide 5 without touching one of the facets 9 or 10 of the prism. As a result, the light beam is reflected by the flat towards the output face FS so as to be totally reflected thereon. It then continues its propagation in the optical guide.

For example, near the end e1 of the optical guide, a large portion of the light rays, emitted by the light source 3, are not reflected, because they do not meet facets 9 or 10 prism. These light rays continue their propagation in the optical guide 5 as if there were no prism. These light rays are thus directed towards the end e2 of the optical guide 5. The properties of the reflection face FR are therefore modified by the presence of these flats. In this way, between the ends e1 and e2 of the optical guide 5, the luminous flux coming out of the optical guide can be uniformly distributed over the entire length of the optical waveguide by this flattening phenomenon.

The invention also makes it possible to obtain, at the output of the optical waveguide, a luminous flux distributed, voluntarily, in a non-uniform manner. In this case, the non-uniform distribution is controlled to obtain a particular visual effect, for example an alternation of illuminated areas and unlit areas.

Thus, the bottom angles D make it possible to adjust the light input of the prisms 8 in the optical guide 5. It is then understood that an optical guide 5 according to the invention makes it possible to compensate for the decrease in the luminous flux passing through the optical guide between the end e1 and the end e2.

The uniform or non-uniform but controlled distribution of the luminous flux is preferably obtained by means of variable flats and, more specifically, the width of the flats along the variable X axis. In a preferred embodiment, the size of the flats 16 is decreasing from the end e1 towards the end e2 of the optical guide 5. This reduction in the size of the flats 16 makes it possible to optimize the guiding of the light rays propagating in the optical guide 5. Near the end e1, the dimension of the flats 16 is large, thus allowing a large part of the light rays not to meet 9 or 10 facet prism and, thus, continue their propagation towards the end e2. Near the end e2, the size of the flats 16 is smaller and smaller until it is zero. There is then a large amount of light rays that meet one of the facets 9 or 10 of a prism. These light rays are then reflected towards the output face FS of the optical guide 5.

This reduction in the size of the flats 16 makes it possible to compensate for the natural luminous decay and, consequently, to uniformly regulate the luminance (ie the luminous intensity emitted by m ² ) at any point in the guide. 5. As a result, the optical guide 5, as a whole, has a homogeneous appearance.

In other embodiments, the size of the flats may be increasing from the end e1 to the end e2, or flat bottom angles may alternate with flat bottom angles, etc.

• le pas 17 entre deux prismes est constant. On entend par « pas » 17 la longueur reliant le sommet d'un prisme avec le sommet du prisme consécutif. Le pas 17 est représenté par une double flèche, sur la figure 4. En d'autres termes, le pas 17 correspond à la base du prisme d'air 15. Le pas 17 entre deux prismes est de préférence de l'ordre de 0,2 à 2 millimètres
• la hauteur 18 des prismes 8 est variable. On appelle « hauteur » 18 la distance entre un point d'une courbe Z et un point du ligne de fond 11 du guide optique 5. La courbe Z, représentée en pointillés sur la figure 4, est une courbe reliant le sommet des angles A de chaque prisme. La hauteur 18 est représentée par une double flèche sur la figure 4. De préférence, la hauteur 18 est de l'ordre de 0,2 à 2 millimètres.

The figure 4 shows a first embodiment of a variable truncation optical guide, that is to say the size of the flats is variable. In the example of the figure 4 , the flats 16 have decreasing dimensions between the end e1 and the end e2 of the optical guide 5, as explained above. As seen in the sectional view of the optical guide 5 of the figure 4 , the flats 16a, 16b, ... 16n have different dimensions from each other and, more specifically, decreasing dimensions. This decrease is obtained by modulating the height of the prisms. More specifically, in the example of figure 4 :

• step 17 between two prisms is constant. The term "step" 17 is the length connecting the apex of a prism with the apex of the consecutive prism. Step 17 is represented by a double arrow on the figure 4 . In other words, the pitch 17 corresponds to the base of the air prism 15. The pitch 17 between two prisms is preferably of the order of 0.2 to 2 millimeters
• the height 18 of the prisms 8 is variable. The distance between a point of a curve Z and a point of the bottom line 11 of the optical guide 5 is called "height". The curve Z, represented in dashed line on the figure 4 , is a curve connecting the vertex of the angles A of each prism. The height 18 is represented by a double arrow on the figure 4 . Preferably, the height 18 is of the order of 0.2 to 2 millimeters.

In the embodiment of the figure 4 the height 18 of a prism 8 increases proportionally with the decrease in size of the corresponding flat 16. The reflection face FR is contained between two curves, along the optical guide. One of the curves is the bottom line 11 and the other curve is the curve Z.

• le pas 17 entre deux prismes est variable. Le pas 17 est représenté par une double flèche sur la figure 5. Le pas 17 entre deux prismes est de préférence inférieur ou égal à 2.5 mm, notamment de l'ordre de 0,2 à 2 millimètres ;
• la hauteur 18 des prismes 8 est constante. La hauteur 18 est représentée par une double flèche sur la figure 5. La hauteur 18 est inférieure ou égale à 2.5 mm, notamment de l'ordre de 0,2 à 2 millimètres. Dans ce mode de réalisation, le pas 17 d'un prisme 8 diminue proportionnellement à la diminution de la taille du méplat 16 correspondant. La hauteur 18 étant constante, la courbe Z est parallèle à l'axe X du guide optique 5.

The figure 5 shows a second embodiment of an optical guide 5 with variable truncation. As in the case of figure 4 , the flats 16 have decreasing dimensions between the end e1 and the end e2 of the optical guide 5. As can be seen in the sectional view of the optical guide 5 of the figure 5 the flats 16a, 16b, ... 16n have decreasing dimensions. In this embodiment, the decay is obtained by modulating the pitch of the prisms. More specifically, in the example of figure 5 :

• step 17 between two prisms is variable. Step 17 is represented by a double arrow on the figure 5 . The pitch 17 between two prisms is preferably less than or equal to 2.5 mm, in particular of the order of 0.2 to 2 millimeters;
• the height 18 of the prisms 8 is constant. The height 18 is represented by a double arrow on the figure 5 . The height 18 is less than or equal to 2.5 mm, in particular of the order of 0.2 to 2 millimeters. In this embodiment, the pitch 17 of a prism 8 decreases in proportion to the decrease in the size of the flat 16 corresponding. Since the height 18 is constant, the curve Z is parallel to the axis X of the optical guide 5.

The two embodiments that have just been described allow one and the other to achieve a decrease in the size of the flats. In addition, they offer the same light output and the same homogeneity of the light emitted by the optical guide 5 over its entire length. The choice of one or other of these embodiments depends on the visual appearance, or aesthetic, wanted.

Are described now the Figures 7 to 9 , corresponding to a second example according to the second embodiment:

A first embodiment of this optical guide according to the invention is represented on the figure 7 . On this figure 7 the reflection face bears the reference FR and the output face bears the reference FS, with the same conventions as before.

In the device of the invention, the reflection face FR of the optical guide may be identical / similar to the reflection face of the optical guide described above. This reflection face is provided with a succession of prisms 8 placed one after the other so as to form a serrated profile face. Prisms 8 may be identical and symmetrical to each other, as in the prior art, or identical and asymmetrical or different from each other.

In the case where the prisms 8 are asymmetrical, as shown on the figure 7 , a reflection is obtained at an angle of about 90 ° with respect to the X axis for the light rays having an angle of incidence of the order of 10 to 40 ° with respect to the axis X of the optical guide. Indeed, in this case, what can be considered as an air prism 30 is formed by the prism background which precedes the prism 8 in transparent matter; this air prism 30 ensures a rectification of the incident light beam. In other words, if we consider that reflection face of the optical guide comprises prisms in transparent material 8 interposed by air prisms 30, then these air prisms 30 change the trajectory of the light rays by straightening the front light rays that they do not meet a prism in transparent matter 8. For example, on the figure 7 , there is shown a luminous ray of trajectory 17 adjusted with an angle of incidence E between 10 and 40 ° with respect to the axis X of the optical guide. This light ray 17 is deflected and straightened along a path 18 by the air prism 30 before being reflected by the facet 10 of the prism 8. It is then redirected, following the trajectory 19, towards the output face FS of the optical guide in a preferred direction generally perpendicular to the axis X of the guide.

Another example of a light ray has been represented on the figure 7 . This light beam, of trajectory 21, has an angle of incidence E 'of about 5 ° with respect to the axis X of the optical guide. This light ray is therefore in the configuration of a total reflection by the prism in transparent material 8. This ray 21 is reflected, by the facet 10 of the prism 8, at an angle of about 90 ° to the X axis to the output side FS of the optical guide. In the case of a light ray having an angle of incidence close to the tangent, that is to say between 0 and 5 ° with respect to the X axis, then the asymmetrical prisms have the same effect on the light ray than symmetrical prisms. On the other hand, as we have seen above, the asymmetric prisms have a rectifying effect, in addition to the reflection effect, when the light ray has an angle of incidence of 10 to 40 °. Asymmetric prisms therefore make it possible to increase the luminous efficiency towards the exit face 6 of the optical guide.

According to the invention, the output face FS of the optical guide has a striated profile. In other words, the output face FS has ridges which make it possible to further straighten the light rays at the output of the optical guide. These grooves are reliefs (bosses or recesses) made in the outlet face 6 of the optical guide. They can be of different shapes.

In the embodiment of the figure 7 these striations 24 each have a prism shape, that is to say that each stripe 24 has two facets 25 and 26, planes. A facet 26 of a streak and a facet 25 of a consecutive streak together form a bottom angle H of about 90 °. The facet 25 of a groove 24 forms, with the axis X of the optical guide, a stripe angle K of the order of 10 to 20 °. So, as shown on the figure 7 and 8 , the ridges 24 of the output face FS have a lower depth than the prisms 8 of the reflection face FR, this in order to keep the optical guide its guiding characteristics. Just like the prisms of the reflection face FR which form a bottom line 11 of the prisms, the striations form a bottom line 16 of the streaks. In other words, the bottom of each streak 24 (as opposed to the top of the striations) forms with the bottom of the consecutive streaks a curve called the bottom line 16 of the streaks. The streaks 24 are therefore contained between the bottom line 16 and a curve connecting the top of all the ridges 24, these two curves generally following the profile of the guide.

These prism-shaped striations can be symmetrical or, on the contrary, asymmetrical as shown on the figure 7 .

In a first variant, all the ridges of the same optical guide are identical. In a second variant, the streaks are different, that is to say they have a stripe angle K and / or a bottom angle H which can vary between the end e1 of the guide and the end e2, in order to allow an evolutionary reflection of the light rays along the entire length of the guide.

Whatever their shape, each streak 24 of the output face FS is located opposite a prism 8 of the reflection face FR. The streaks 24 of the output face FS therefore have a pitch identical to the pitch of the prisms 8 of the reflection face FR. In other words, to be effective, the active areas of the output face FS, that is to say the facets 25 of the grooves 24, are located opposite (at least partially opposite) the active zones of the prisms 8 of the reflection face FR, that is to say facets 10 of the prisms 8.

So, in the example of the figure 7 , the incoming trajectory light beam 17 undergoes, as previously explained, a first reflection by the facet 10 of a prism 8. It is then refracted by the facet 25 of a streak 24 and leaves the optical guide with a negative angle G relative to the normal N to the X axis. Similarly, the light ray 21 undergoes the same path from the facet 10 of the prism. The exit angle G thus obtained depends, of course, on the slope of the groove 24. In the example of the figure 3 this exit angle G is of the order of -20 ° relative to the normal N.

This embodiment of the output face in prisms thus makes it possible to send light rays in a direction impossible to reach by total reflection on the prisms of the reflection face when the exit face is smooth. It makes it possible to obtain a negative angle G of approximately -25 ° relative to normal N.

According to figure 7 the angle between the mean direction of propagation in the optical waveguide and the average direction of the light beam out of the optical waveguide is obtuse: such an angle can not be obtained with a smooth exit face. On the figure 8 another embodiment of the output face FS of the optical waveguide of the invention is shown. In this embodiment, the ridges 24 do not have plane facets; on the contrary, the ridges 24 have a curved profile. More specifically, according to a sectional view, each groove 24 has an arcuate shape. In other words, each stripe 24 forms a kind of dome forming, with the consecutive streak, a bottom angle H. The tangent at the base of the dome makes an angle K of 10 ° to 20 ° relative to the axis X of the guide optical.

Each stripe 24 of the output face FS is located opposite a prism 8 of the reflection face FR. The streaks 24 therefore have a pitch identical to the pitch of the prisms 8 of the reflection face FR. In other words, the ridges 24 of the output face FS are located opposite the active areas of the prisms 8 of the reflection face FR.

This embodiment has the advantage of allowing a controlled distribution of light around the normal N, which makes it possible to homogenize the appearance of the guide for an outside observer. For this, two examples of light rays have been represented on the figure 8 , which may have different directions at the output of the optical guide.

The first example of a light beam is the incoming light ray 17 having an angle of incidence E of 10 to 40 ° with respect to the X axis. This light beam is first deflected by an air prism 30 then reflected by about 90 ° by a prism 8 to the output face FS. When it encounters a streak 24 of the output face FS, said light beam undergoes a refraction of a negative angle G with respect to the normal N (path 20).

The second example of light ray is the incoming trajectory ray 21 having an angle of incidence E 'with the axis X. This light ray 21 undergoes a first reflection by a prism 8 of the reflection face FR. When it encounters a streak 24 of the exit face 6, said light ray 21 undergoes refraction with a positive angle G relative to the normal N (path 23). This profile in domes of the output face FS thus makes it possible to distribute the light laterally in several directions.

On the Figure 9A a third embodiment of the output face of the optical waveguide of the invention is shown. In this embodiment, the ridges 24 of the exit face FS form curved facet prisms. More specifically, each groove 24 comprises a curved facet 28 and a flat facet 27, each curved facet 28 being consecutive to a plane facet 27. The curved facet 28 and the plane facet 27 of a consecutive streak together form a bottom angle H of the order of 90 °. The tangent to the curved facet 28 forms, with the axis X of the optical guide, a stripe angle K of the order of 10 to 20 °. In this embodiment, the striations are contiguous with each other, that is to say a streak is contiguous to the next streak. This third embodiment combines features of the first embodiment with features of the second embodiment, which optimizes the guidance of the light rays through the optical guide, while ensuring a good homogeneity of the light and a sending light in directions inaccessible classically.

As shown on the Figure 9A the first example of light ray 17 is refracted, by a streak 24 of the exit face 6, with a negative angle G with respect to the normal N. The second example of light ray 21 leaves the optical guide with a negative angle G relative to the normal N, different from the angle G formed by the light ray 20. However, as seen on the Figure 9A , depending on the location on the streak, the value of the exit angle G differs. It is therefore understood that the exit angle G varies as a function of the location, on the facet 28 of the streak 24, of the point of contact of the light beam with the streak. In other words, the value of the exit angle depends on the radius of curvature of the curved facet 28. Thus, by modifying the curvature of the curved facets 28 of the ridges 24, it is possible to obtain a whole range of exit angles. In other words, such a curved prism outlet face makes it possible to obtain both a prism effect and a burst effect of the light beam.

On the Figure 9B , there is shown a variant of the embodiment of the Figure 9A . In this variant, the ridges 24 of the exit face FS form non-contiguous curved facet prisms. More specifically, each groove 24 comprises a curved facet 28 and a flat facet 27, each curved facet 28 being separated from the flat facet 27 of the next streak by a flat surface 29. The striations 24 are therefore separated from each other by flats. 29. In this variant, the active zone of each stripe 24, that is to say the curved facet 28, is placed opposite (at least partially) to the active zone of the prism 8, that is to say of the facet 10 of the prism in order to make the refraction by the striations as effective as possible. The flat part 29, in this variant, makes it possible to propagate at the end e2, the light rays not refracted by the striations 24.

To the figure 6 is shown a light guide, according to a third embodiment, which is modified both on its exit face and on its reflection face in accordance with the invention: the exit face 6 has ridges that allow to straighten the light rays at the output of the optical guide, that is to say to get them out of the optical guide with a negative angle relative to the normal N to the X axis of the guide., as shown in FIG. figure 8 and the reflection face comprises prisms such as those described using the figure 4 especially. Associating the two embodiments of the invention on the same light guide is very advantageous.

The streaks of the exit face FS can be of different shapes, for example, in the form of prisms or domes or a combination of prisms and domes, as seen above with the Figures 7 and 8 . They are located opposite the active areas of the prisms 8 of the reflection face.

The prisms of the reflection face can be those described in figure 3, 4 or 5 . The presence of flats 15 in the optical guide enables a light beam to propagate in the optical guide without touching one of the facets 9 or 10 of the prisms 8 of the reflection face FR. As a result, the light beam is reflected towards the output face of the light guide, further down the guide, which distributes the light flux uniformly between the ends e1 and e2 of the light guide.

It should be noted that the examples described above, and, more generally, the light guides according to the invention, have preferably circular sections, insofar as such a section is the most appropriate in terms of optical guidance. This section is also very suitable in terms of focusing of the light. But the invention also relates to light guides of different section, for example a conical section, for example of elliptical, hyperbolic or parabolic, at least partially, or oval. Sections parallelogram type, square, rectangle are also possible but less interesting in terms of light guidance.

Note also that, both for the streaks of the exit face and for the prisms of the reflection face, the striations and / or the prisms may have variable widths (that is to say, affect more or less the width of the face in question, either wholly or partially, or with a variable width along the length of the guide).

The invention therefore proposes two light guide embodiments, alternative, or cumulative, to have a better visual homogeneity of the guide once lit and / or have more control over the orientation of the light emitted by the light guide. To cumulate the two achievements is very advantageous, because they contribute to the same goal, that of improving the visual aspect of the light guides once lit.

Claims (19)

1. Lighting and/or signalling device for a motor vehicle, comprising at least one source of light (3) which emits a light beam (4), and at least one optical guide in which the light beam (4) is propagated, the said optical guide comprising:

   - an output surface (FS) of the light beam; and

   - another reflection surface (FR), opposite the output surface, having a toothed profile which forms a reflection surface of the light beam,

   - the reflection surface (FR) comprising a succession of prisms (8), each prism (8) forming, together with the following prism (8), a base angle (D), with at least one base angle (D) of the reflection surface (FR) which is truncated,

   characterised in that the cross-section of the optical guide is circular or elliptical or conical, or at least partially hyperbolic or parabolic; and

   - in that the said prisms of the reflection surface (FR) have a constant pitch (17) and variable heights (18).
2. Lighting and/or signalling device for a motor vehicle, comprising at least one source of light (3) which emits a light beam (4) and at least one optical guide in which the light beam (4) is propagated, the said optical guide comprising:

   - an output surface (FS) of the light beam; and

   - another reflection surface (FR), opposite the output surface, having a toothed profile which forms a reflection surface of the light beam,

   - the reflection surface (FR) comprising a succession of prisms (8), each prism (8) forming, together with the following prism (8), a base angle (D), with at least one base angle (D) of the reflection surface (FR) which is truncated,

   characterised in that the output surface (FS) has a profile comprising striations (24); and

   - each striation (24) of the output surface (FS) is situated opposite a prism (8) of the reflection surface (FR).
3. Lighting and/or signalling device according to one of the preceding claims, characterised in that at least some of the base angles (D) of the reflection surface (FR) comprise a truncated area (16), the dimension in longitudinal cross-section of the truncated area being variable from one angle to another.
4. Lighting and/or signalling device according to one of the preceding claims, characterised in that the dimension of the truncated areas (16) of the reflection surface (FR) decreases the further it is away from the source of light (3).
5. Lighting and/or signalling device according to one of the preceding claims, characterised in that the reflection surface (FR) comprises both prisms with an angle with a truncated base, and prisms with an angle with a non-truncated base.
6. Lighting and/or signalling device according to claim 2, characterised in that the prisms of the reflection surface (FR) have variable pitches (17) and a constant height (18).
7. Lighting and/or signalling device according to claim 2, characterised in that the prisms of the reflection surface (FR) have a constant pitch (17) and variable heights (18).
8. Lighting and/or signalling device according to one of the preceding claims, characterised in that the pitch (17) of the prisms of the reflection surface (FR) has a dimension which is 2.5 mm or less, and in particular is approximately 0.2 to 2 mm.
9. Lighting and/or signalling device according to one of the preceding claims, characterised in that the height (18) of the prisms of the reflection surface (FR) is 2.5 mm or less, and in particular is approximately 0.2 to 2 mm.
10. Lighting and/or signalling device according to one of the preceding claims, characterised in that the prisms of the reflection surface (FR) are symmetrical.
11. Lighting and/or signalling device according to one of the preceding claims, characterised in that the prisms of the reflection surface (FR) are asymmetrical.
12. Lighting and/or signalling device according to claim 2, characterised in that the striations of the output surface (FS), or at least one of them, each have a curved form, and in particular an arc of a circle.
13. Lighting and/or signalling device according to claim 2, characterised in that the striations of the output surface (FS), or at least one of them, each have the form of a prism, in particular with flat facets (25, 26).
14. Lighting and/or signalling device according to claim 13, characterised in that the prisms of the output surface (FS) are symmetrical or asymmetrical.
15. Lighting and/or signalling device according to claim 2, characterised in that the striations (24) of the output surface (FS) each comprise a curved facet (28) and a flat facet (27).
16. Lighting and/or signalling device according to claim 2, characterised in that the striations (24) of the output surface (FS) are contiguous or non-contiguous.
17. Lighting and/or signalling device according to claim 2, characterised in that each striation of the output surface (FS) forms a striation angle (K) with an axis (X) of the optical guide, of approximately 1 to 30°.
18. Lighting and/or signalling device according to one of the preceding claims, characterised in that it comprises at least two sources of light which are each placed at one end of the optical guide.
19. Lighting and/or signalling device according to one of the preceding claims, characterised in that it comprises a plurality of optical guides with a common intersection, at least one source of light being situated at this point of intersection.

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