EP2743567A1 - Primary optical element, lighting module and headlight for motor vehicle - Google Patents

Abstract

The primary optical element comprises a plurality of light guides (3a-3d), connected at the output to a corrective part (4) having an at least partly dome-shaped, substantially dome-shaped exit face (41). light (3a-3d) and the corrective part (4) forming a one-piece structure. The lighting module comprises a plurality of light sources (1a-1d), the primary optical element (2) and an associated projection optical element (5). The outputs of the guides (3a-3d) are positioned in an object focal plane of the projection lens (5). The projector incorporates one or more optical modules.

Description

The technical field of the invention is that of lighting modules for motor vehicles.

A motor vehicle is equipped with headlamps, or headlights, intended to illuminate the road in front of the vehicle, at night or in the case of reduced luminosity. These headlamps can generally be used in two lighting modes: a first mode "high beam" and a second mode "low beam". The "high beam" mode provides strong illumination of the road far ahead of the vehicle. The "low beam" mode provides more limited road lighting, but still offers good visibility without dazzling other road users. These two lighting modes are complementary. The driver of the vehicle must manually switch modes depending on the circumstances, at the risk of inadvertently dazzle another user of the road. In practice, changing the lighting mode manually can be unreliable and sometimes dangerous. In addition, the dipped beam mode provides visibility sometimes unsatisfactory for the driver of the vehicle.

To improve the situation, floodlights with Adaptive Driving Beam (ADB) function have been proposed. Such an ADB function is intended to automatically detect a user of the road likely to be dazzled by a beam of light emitted in headlight mode by a projector, and to modify the outline of this beam of light in a manner to create a shadow zone at the location of the detected user. The advantages of the ADB function are multiple: comfort of use, better visibility compared to a lighting in dipped beam mode, better reliability for the change of mode, risk of dazzling greatly reduced, driving safer.

• quatre modules optiques primaires, sources de lumière, chaque module optique primaire comportant trois sources de lumière LED, associées à trois guides de lumière respectifs, et une lame support ; et
• quatre éléments optiques secondaires de projection, en l'espèce des lentilles, respectivement associés aux quatre modules optiques primaires.

The document EP2280215 discloses an example of a lighting system for a motor vehicle headlamp, having an ADB function. The system includes

• four primary optical modules, light sources, each primary optical module comprising three LED light sources, associated with three respective light guides, and a support blade; and
• four secondary optical projection elements, in this case lenses, respectively associated with the four primary optical modules.

The light emitted by each LED enters the associated light guide and is emitted from an outlet end of the guide, rectangular in shape, to the associated secondary optical element. The light emitted by each optical guide exit end and projected by the secondary optical element forms a vertical light segment at the front of the vehicle. The light segments produced overlap partially in the horizontal direction. The LEDs can be switched on independently of each other, selectively, to obtain the desired illumination.

Such a lighting system nevertheless has certain disadvantages.

In particular, the rays emitted by each light guide undergo refraction at the interface between the output surface of the guide and the surrounding medium (that is to say the air). This has the effect of strongly spacing the rays of the optical axis of the secondary optical element. As a result, part of the rays emitted by the exit surface of each light guide does not penetrate into the associated secondary optical element.

Such a lighting system does not provide good quality imaging.

The present invention improves the situation.

For this purpose, the invention relates to a primary optical element for a motor vehicle lighting module, comprising a plurality of light guides, characterized in that the light guides are connected at the output to a corrective part comprising a face of light. at least partially dome-shaped substantially spherical outlet, the light guides and the corrective part forming a monobloc structure.

From the outset, it will be noted that by "substantially spherical dome" is meant a surface whose shape at least partially matches that of a sphere. In other words, the corrective part is defined at least by an exit face having at least one spherical portion.

When a primary light source is placed facing the entrance of a guide, light rays emitted by this source penetrate and propagate in the guide and continue their journey in the corrective part of the primary optical element. All the rays leaving the guide, in other words the light beam at the exit of the guide, constitutes a secondary light source.

It is known that a light ray penetrating into an optical guide with an opening α with respect to the normal to the entrance surface of this guide is folded towards the longitudinal axis of the guide by the laws of refraction at an arcsine angle ( 1 / n * sin (α)). Thanks to the invention, this ray passes directly from the guide to the corrective part of the primary optical element. The reduced opening of the rays is thus preserved.

In addition, at the exit of the corrective part, the light rays are not or little deviated due to the substantially spherical dome shape of the output face of this corrective part.

The one-piece structure ensures an excellent connection between the guides and the corrective part of the primary optical element.

Thus, thanks to the corrective part connected to the output of the light guides and the monobloc structure of the primary optical element, the optical efficiency is greatly improved.

Advantageously, the respective refractive indices of the light guides and the corrective part are substantially identical.

By "substantially identical" is meant refractive indices equal to one hundredth. Thus, at the exit of the guides, the rays do not undergo or almost no refraction.

In a particular embodiment, the light guides and the corrective part are made of the same material.

In this case and advantageously, the light guides and the corrective part are from the same polymer.

By "same material", it is meant that the light guides and the corrective part are made from materials that are at least base polymer, for example PMMA. However, these materials may have different charges.

Preferably, the substantially spherical dome-shaped exit face is centered substantially at the exit of one of the light guides. Thus the rays issuing from a guide substantially at the center of the sphere enveloping the corrective portion are normal to the outlet face thereof and are therefore not deviated to the interface between the corrective part and the surrounding air . The spokes emerging from an eccentric guide are for their part slightly deviated to the exit interface.

In a particular embodiment, the corrective part has substantially the shape of a half-sphere. In other words, the exit face has a half-spherical shape over its entire surface. Where appropriate, the exit face is constituted by the spherical portion, this spherical portion extending over the entire surface of the exit face.

Alternatively, the corrective portion may be a truncated ball portion, i.e., cut on either side of the spherical portion formed on the exit face. Where appropriate, the exit face is constituted by the spherical portion, this spherical portion extending over the entire surface of the exit face.

In another exemplary embodiment, the exit face may comprise at least one portion adjacent to the spherical portion, the adjacent portion extending from the spherical portion to the rear of the corrective portion according to a progressive radius of curvature. If necessary, the radius of curvature gradually decreases.

Advantageously, at least one light guide has a face, upper or lower, having a cylindrical portion shape.

The curved shape, in a portion of a cylinder, of the upper or lower face of the guide, contributes to concentrating the light intensity in an area, respectively higher or lower, of the secondary light source output of the guide.

In a particular embodiment, the entrance face of at least one light guide comprises a convex portion.

This also helps to focus the light intensity in an area of the secondary light source.

Advantageously, the entry face of at least one light guide comprises a concave portion.

This helps to spread the light in an area of the secondary light source.

Advantageously, the input face of said light guide extends at least partially in a plane inclined to the vertical by an angle between 0 ° and 45 °.

Preferably, said plane is inclined at an angle between 10 ° and 30 °.

In a particular embodiment, at least one light guide comprises at least one spreading face, said spreading face being shaped so as to widen the cross section of the guide from its input face to its exit

The widening, low or high, of the guide makes it possible to spread the light at the bottom or the top of the secondary light source at the exit of the guide.

In another embodiment, the light guides being juxtaposed two by two along a line, one of the two end guides of said line comprises a side spreading face.

For example, the guides can all be aligned along a single line.

Alternatively, the guides may be arranged along at least two lines, at least one of the lines being disposed below another of the lines. For example, each guide of at least one of the lines can be arranged exactly below a guide of another of the lines. In another example, each guide of at least one of the lines may be disposed below, laterally offset, from one guide to another of the lines.

The lateral enlargement of the guide allows the light to be spread on the side of the secondary light source at the exit of the guide.

In an alternative embodiment, an area of the output face of the corrective part has a radius of curvature which gradually decreases.

In another variant embodiment, said zone of the exit face is a lateral, lower or upper zone.

With this, the rays exiting the area of the exit face of the corrective portion whose radius of curvature is increased are further folded towards an optical axis of the optical element.

The invention also relates to an optical assembly comprising the primary optical element as defined above and a plurality of light sources, each source being associated with a single guide.

The invention also relates to an optical lighting module for a motor vehicle headlamp, characterized in that it comprises a plurality of light sources, a primary optical element as previously defined and an associated projection optical element, the outputs of guides of the primary optical element being positioned in an object focal plane of the projection lens.

The positioning of the "output plane" of the guides (this "exit plane" designating the surface, not necessarily plane, in which the outputs of the guides extend) in the object focal plane of the projection element makes it possible to create the infinite an image of the secondary light sources at the exit of the guides, thus producing luminous segments of corresponding forms.

The invention also relates to a motor vehicle headlight, characterized in that it comprises at least one optical module as previously defined, including several optical modules.

• la figure 1 représente une vue en perspective du module d'éclairage, en position opérationnelle ;
• la figure 2 représente une vue de dessus du module de la figure 1 ;
• la figure 3 représente une vue latérale du module de la figure 1 ;
• la figure 4 représente des segments lumineux produits par le module de la figure 1 sur un mur situé à environ 25 mètres du module ;
• la figure 5 représente un vue de dessus de l'élément optique primaire de la figure 1 ;
• la figure 6 représente une vue latérale de l'élément optique primaire de la figure 1 ;
• la figure 7 représente le trajet de rayons entre une point d'extrémité de sortie d'un premier guide, situé sensiblement sur l'axe optique d'un élément de projection, et la sortie du module optique de la figure 1 ;
• la figure 8 représente le trajet de rayons entre un point d'extrémité de sortie d'un deuxième guide, situé hors de l'axe optique de l'élément de projection, et la sortie du module optique de la figure 1 ;
• la figure 9 représente une deuxième forme de réalisation de l'élément optique primaire, en vue latérale ;
• la figure 9' représente une vue en perspective de l'élément optique primaire de la figure 9 ;
• la figure 10 représente le trajet de rayons lumineux dans un guide de la figure 9 ;
• la figure 11 représente un élément optique primaire selon une troisième forme de réalisation ;
• la figure 12 représente un élément optique primaire selon une quatrième forme de réalisation.

Various embodiments of the primary optical element, the optical assembly, the lighting module and the motor vehicle headlight according to the invention will now be described with reference to the appended drawings in which:

• the figure 1 represents a perspective view of the lighting module, in operational position;
• the figure 2 represents a top view of the module of the figure 1 ;
• the figure 3 represents a side view of the module of the figure 1 ;
• the figure 4 represents light segments produced by the module of the figure 1 on a wall about 25 meters from the module;
• the figure 5 represents a view from above of the primary optical element of the figure 1 ;
• the figure 6 represents a side view of the primary optical element of the figure 1 ;
• the figure 7 represents the ray path between an output end point of a first guide, located substantially on the optical axis of a projection element, and the output of the optical module of the figure 1 ;
• the figure 8 represents the ray path between an exit end point of a second guide, located outside the optical axis of the projection element, and the output of the optical module of the figure 1 ;
• the figure 9 represents a second embodiment of the primary optical element, in side view;
• the figure 9 ' represents a perspective view of the primary optical element of the figure 9 ;
• the figure 10 represents the path of light rays in a guide to the figure 9 ;
• the figure 11 represents a primary optical element according to a third embodiment;
• the figure 12 represents a primary optical element according to a fourth embodiment.

From the outset it will be noted that, for the sake of clarity, the corresponding elements shown in different figures bear the same references, unless otherwise indicated.

An orthogonal three-dimensional coordinate system is also represented on the figure 1 , the z axis corresponding to the vertical.

The Figures 1 to 3 represent an optical lighting module, in operational position, intended to equip a motor vehicle headlamp, according to a first embodiment. The Figures 1, 2 and 3 respectively represent a perspective view, a top view, in the direction ZZ ', and a side view, in the direction XX', of the optical module.

• une pluralité de sources de lumière primaires, référencées 1a-1d ;
• un élément optique primaire 2 et
• un élément optique secondaire de projection 5, ayant un axe optique 6.

The lighting module includes:

• a plurality of primary light sources, referenced 1a-1d;
• a primary optical element 2 and
• a secondary optical projection element 5, having an optical axis 6.

By definition, the front of the module designates the part to the right of the figure 1 and the back of the module to the left.

The primary light sources 1a-1d are, in the particular example described here, light emitting diodes, or LEDs. However, LEDs could be replaced by other light sources.

The primary optical element 2 comprises a number N of light guides, also called waveguides or optical guides, referenced 3a-3d, respectively associated with the N primary light sources 1a-1d, and a corrective part 4. The N light guides 3a-3d are connected, connected at the output to the rear of the corrective part 4, the whole forming a monobloc structure. By "monobloc structure" is meant that the elements of the structure (here the guides 3a-3d and the corrective part 4) are not separable without destruction of at least one of the elements.

In the particular example described here, the number N of guides is equal to four. Of course, this number could be greater or less than four. It is, however, preferably strictly greater than one.

The corrective part 4 is a sphere portion, or a ball portion, centered on the outlet of one of the guides, here the guide 3b. More specifically, in the particular example of Figures 1 to 3 , the corrective part 4 is a half-ball whose center is situated in the exit plane of the guide 3b and on the optical axis 6. In a variant, the exit plane of the guide 3b could be substantially offset with respect to the center of the sphere of a distance less than or equal to 10% of the value of the radius of the sphere, preferably along the optical axis 6. The front surface 41 of the corrective part 4, in the form of a spherical dome or spherical portion , constitutes an exit front face. The rear 40 of the corrective part 4 extends here in the cutting plane of the half-sphere. It could however have any shape, provided to ensure the connection with the outputs of the guides 3a-3d and not to change the path of the rays from the output ends of the guides and propagating in the corrective part 4.

By way of example, the corrective part may be a truncated ball portion, that is to say cut off on each side of the spherical portion formed on the exit face.

Alternatively, it may be formed of the first and second ball portions, adjacent to the peripheral portion, and which extend along a progressive radius of curvature until reaching the rear 40 of the corrective portion 4.

The light guides 3a-3d and the corrective part 4 are made of the same material and have the same refractive index.

By "same material" is meant that the light guides 3a-3d and the corrective part 4 are made of the same material or are derived from the same polymer. If they come from the same polymer, the guides may have a charge different from that of the corrective part 4. As an illustrative example, the guides may be manufactured in PMMA-HT (English Polymethyl MethAcrylate High Temperature - high temperature polymethyl methacrylate) with a refractive index of 1.490 and resistant to high temperatures, and the PMMA-8N corrective part having a refractive index equal to 1.491 and less expensive.

By "same refractive index" is meant that the refractive index of the guides 3a-3d and that of the corrective part 4 are equal to the nearest hundredth.

The material constituting the guides 3a-3d and the corrective part 4 is transparent. This is a material for an optical lens, such as an organic material or possibly glass.

The use of 3a-3d light guides allows more tolerance in the positioning of light sources 1a-1d. This avoids the need to accurately position the light sources 1 to 1 d relative to each other.

• une face arrière 30a (30b-30d) d'entrée de la lumière ;
• une sortie avant, ou extrémité de sortie ou interface de sortie, 31a (31 b-31 d) jouant un rôle de source de lumière secondaire, reliée à la partie correctrice 4 ;
• deux faces latérales 32a (32b-32d), 33a (33b-33d) ;
• une face supérieure 34a (34b-34d) ;
• une face inférieure 35a (35b-35d).

Each light guide 3a (3b-3d) comprises

• a rear face 30a (30b-30d) of light input;
• a front output, or output end or output interface, 31a (31b-31d) acting as a secondary light source, connected to the corrective part 4;
• two side faces 32a (32b-32d), 33a (33b-33d);
• an upper face 34a (34b-34d);
• a lower face 35a (35b-35d).

For the sake of clarity, some references of guide faces are not shown in the figures, so as not to overload them.

In addition, each guide 3a (3b-3d) extends along a longitudinal axis crossing the input face 30a (30b-30d) at its center, and the output 31a (31b-31d).

In an alternative embodiment, the guides 3a-3d could comprise a sheath surrounding the interior of the guide, the light being intended to propagate inside the guide by successive total reflections on an inner wall of the sheath.

The cross section of each guide 3a (3b-3d) (that is to say transverse to the optical axis of the guide) here has a shape of parallelogram, and more precisely rectangle. However, the cross section of the guides could be of any shape. It could for example include curved sides. In any case, it is adapted to produce a desired form of light beam at the output of the optical module.

The outputs 31a-31d of guides, here rectangular, are secondary light sources for producing respective light beams at the output of the optical module. These light beams have generally rectangular shapes in cross section (that is to say transverse to the optical axis 6).

The respective axes of the guides 3a-3d extend horizontally and orthogonally to the cutting plane of the half-sphere of the corrective part 4. The N guides 3a-3d are here juxtaposed and form a horizontal row. Alternatively, the guides could be juxtaposed two by two along any line, straight or curved. They could for example be arranged in a fan.

The input face 30a (30b-30d) of each guide 3a (3b-3d) is here flat and vertical. It is positioned facing (that is to say at right) a primary light source 1a (1b-1d), the light emitted by it being intended for penetrate at least partially into the associated guide 3a (3b-3d) by this input face 30a (30b-30d). For each light source pair 1a (1b-1d) and associated guide 3a (3b-3d), the distance between an output plane of the light source 1a (1b-1d) and the input face of the associated guide 3a (3b-3d) is between 0.1 millimeters and 1 millimeter.

The upper faces 34a-34d of the guides are planar and extend in the same horizontal plane.

The figure 4 represents the light segments 7a-7d respectively produced by the secondary light sources 31a-31d of the guides 3a-3d, at the output of the optical module, on a wall located about 25 meters in front of the projection element 5.

With reference to the figure 3 which represents a lateral view in the direction XX 'of the optical module of the figure 1 , the lower faces 35a-35d of the guides 3a-3d are spreading faces shaped so as to widen the cross section of the guide 3a (3b-3d), continuously, from its inlet face to its face output, each guide 3a (3b-3d) flaring down from its entrance to its exit. The lower faces 35a-35d are here curved and have a flared shape. Alternatively, they could be flat and inclined relative to the longitudinal axis of the guide. The lower or lower flare of each guide 3a (3b-3d) allows a vertical downward spread of the secondary light source 31a (31b-31d) at the outlet of the guide, which corresponds to a spread towards the top of the light segment produced as it appears on the figure 4 . Thanks to the shaping of the bottom of the guides 3a-3d, the top of each light segment 7b-7d is softened, the light intensity decreasing vertically upwards gradually.

With reference to Figures 1 and 2 , the row of light guides 3a-3d comprises a left lateral end guide 3d and a right lateral end guide 3a, when the optical module is observed in the direction YY '. The left end guide 3d is intended to produce a right light segment. Conversely, the right end guide 3a is intended to produce a left light segment.

With reference to the figure 2 , the left end guide 3d comprises a left lateral spreading face 33d shaped to expand laterally, continuously, the cross section of the guide from its input face to its output. The left side face 33D is here curved and flares from the input face 30d of the guide 3d to its output 31d. As a variant, the lateral face 33d could be flat and inclined with respect to the optical axis of the guide 3d. The lateral widening of the guide 3d allows lateral spreading to the left of the secondary light source 31d at the output of the guide 3d, which corresponds here to a lateral spread to the right of the light segment produced 7d as it appears on FIG. figure 4 . By shaping the left side of the 3d guide, the right edge of the light segment 7d is softened, the light intensity decreasing laterally to the right gradually.

It should be emphasized that the optical module represented on Figures 1 to 3 is intended to equip a right projector of a motor vehicle. The optical module for a left motor vehicle headlight comprises a right end light guide 3a having a flared right side face similar to the left side face 31d of the guide 3d of the figure 2 .

The role of the corrective part 4, in cooperation with the light guides 1a-1d, is twofold.

It allows on the one hand to improve the optical efficiency of the optical module. The entry of the guides 3a-3d has the effect of reducing the opening of the light rays emitted by the primary sources 1a-1d, the rays entering the guides 3a-3d being folded by the laws of refraction. In addition, at the interface between each light guide 3a (3b-3d) and the corrective part 4, the light rays are not deflected due to the connection between the guides 3a-3d and the corrective part 4. this, the reduced opening of the rays is preserved. Finally, the light rays issuing from the corrective part 4 by the exit face 41 are not or little deviated thanks to the spheroidal dome shape of the outlet face 41. Indeed, the half-spherical corrective part 4 being centered on the output of one of the guides, here the guide 3b, a radius from the exit plane of this guide 3b at the optical axis 6 is normal or almost normal to the output face 41 and is therefore not not deviated to the interface between the corrective part 4 and the surrounding air. A ray originating from an area remote from the optical axis 6 is folded towards this optical axis 6. The refraction at the interface between the corrective part 4 and the surrounding medium (air) is in a way "compensated" by the shape spherical, or substantially spherical, of the exit face 41.

The corrective part 4 also makes it possible to correct the field aberrations of the optical system and thus ensure good quality imaging, as will be explained further later.

The projection element 5 is here a convergent optical lens having the axis 6 for optical axis. The distance separating the corrective part 4 and the projection optical element 5 is strictly greater than zero and adapted so that the plane in which the outputs of the guides 31a-31 extend coincides with the object focal plane of the lens. projection 5. With this, the optical module is adapted to create an infinite image of the secondary light sources 31a-31d formed at the output ends of the guides 3a-3d.

• réduire l'ouverture des rayons pénétrant dans le guide et
• mettre en forme le faisceau lumineux destiné à sortir du module optique de manière à concentrer la lumière dans une zone de portée (c'est-à-dire une zone destinée à éclairer de façon importante) et à l'étaler en dehors de cette zone de portée et
• s'affranchir des erreurs de positionnement des sources de lumière primaires.

In operation, the light rays emitted by a light source 1a (1b-1d) penetrate, at least partially, into the associated guide 3a (3b-3d) by its input face 30a (30b-30d). These rays are channeled in the guide 3a (3b-3d) by successive total reflections and propagate inside the guide 3a (3b-3d) from its input face 30a (30b-30d) to its output 31a (31b-31d) as shown in the figure 5 . As previously explained, each light guide 3a (3b-3d) has the effect of:

• reduce the opening of rays entering the guide and
• shaping the light beam to exit the optical module so as to focus the light in a range area (ie, a large illumination area) and spread it out of that area scope and
• to overcome positioning errors of primary light sources.

où n représente l'indice de réfraction à l'intérieur du guide 3a (3b-3d).A light beam emitted by one of the light sources 1a (1b-1d) and having an opening α with respect to the optical axis of the associated guide 3a (3b-3d) is folded down, at the entrance to the guide, by the laws of refraction in $\mathit{arcsin}\left(\frac{1}{\mathrm{not}}\mathrm{.}\mathit{sin}\left(\alpha \right)\right),$

where n represents the refractive index inside the guide 3a (3b-3d).

At the interface between the output 31a (31b-31d) of the guide 3a (3b-3d) and the input 40 of the corrective part 4, the spokes coming out of the guide 3a (3b-3d) are not deflected. The reduced opening of the rays is thus preserved.

The spokes then pass through the corrective part 4 in straight lines and exit through the exit face 41 while propagating forwards towards the projection element 5. The Figures 7 and 8 respectively represent, in top view, the path of a light beam emerging from the guide 3b located substantially on the optical axis 6 and the path of a light beam coming out of the guide 3c located outside the optical axis 6. For the sake of clarity, the guides are not represented on these Figures 7 and 8 .

With reference to the figure 7 , the radii 8b emitted by the output 31b of the guide 3b located substantially on the optical axis 6 are virtually deviated at the interface between the corrective part 4 and the surrounding medium (air), when they pass through the face of output 41, thanks to the spherical shape of the interface.

With reference to the figure 8 , the radii 8c emitted by the output 31c of the guide 3c located outside the optical axis 6 are slightly folded towards the optical axis 6 at the interface between the corrective part 4 and the surrounding air, when they pass through the exit face 41.

The corrective part 4 makes it possible to reduce the inclination of the rays when they impact the projection lens 5, not only for the rays issuing from the guide 3b positioned at the spherical center, but also for the rays coming from the eccentric guides which undergo a projection. slight deviation at the exit of the corrective part 4. Thus, the corrective part 4 decreases the optical aberrations.

The ball portion shape of the corrective portion 4 improves imaging in the field. One can thus generate several light segments, with good imaging, using a same primary optical element 2 and from different light guides 3a-3d positioned on or off the optical axis 6. The half 4, slightly modifying the orientation of the rays emitted by the Guide outputs 31a, 31c and 31d which are offset from the optical axis 6, at the output interface 41, have a field corrector effect.

The light beams emitted by the outputs 31a-31d of the guides 3a-3d, after passing through the corrective optical element 4, propagate towards the projection optical element 5 and pass therethrough. The outputs 31a-31d being positioned in the object focal plane of the projection element 5, the beams emerging from the projection element 5 are beams of parallel rays forming light segments of generally rectangular shape.

With reference to the figure 4 , the light segments 7a-7c produced by the outputs 31a-31c of the guides 3a-3c have vertical rectangle shapes and have in their upper part a spread of the light induced by the low flare of the guides 3a-3c. The light segment 7d has a double spread of the light: a high spread of the light induced by the low flare of the 3d guide and a right lateral spreading induced by the left lateral flare of the 3d guide. In the areas of spread of the light, the light intensity decreases gradually.

It will be emphasized here that the optical module of the invention has an excellent optical efficiency. The luminous flux emitted by the sources undergo little loss and are recovered largely at the output of the module to create light beams capable of forming light segments.

In addition, the optical module can produce light segments whose shapes are perfectly controlled. In particular, the vertical boundaries of the light segments have a shape and clarity well controlled. "Modulation" or "microstructure" type patterns could be added to the surfaces of the projection element 5 to intentionally add a controlled cut-off blur.

With reference to Figures 9 and 10 a second embodiment of the light guides 3a-3d will now be described. Only the elements that differ from the first embodiment are described below.

On the figure 9 there is shown a side view, in the direction XX ', of the light guide 3a. The figure 9 ' represents a perspective view of the guides 3a-3d according to this embodiment. The upper face 34a of the guide 3a is a curved surface generally having a cylindrical portion shape. This has the effect of concentrating the light intensity in the upper part of the beam coming out of the guide 3a, which corresponds to a zone (called "range area") located in the bottom of the light beam produced at the output of the optical module. With reference to the figure 10 the shape of the upper face 34a is adapted to optically conjugate the point A, located in the air and corresponding to a light emission point of the source 1a, and the point B, located in the material of the guide 3a, at the exit 31a of the guide. The specific shape of the surface 34a can be calculated by applying Fermat's theorem to maintain the constant optical path between the points A and B. Thus, a modification of the shape of the input face 30, in particular of its upper portion 300a, causes a modification of the shape of the upper face 34a.

With reference to the figure 10 , the inlet face 30a of the guide 3a extends partially in a plane inclined to the vertical of an angle θ, between 0 ° and 45 °, preferably between 10 ° and 30 °. In addition, the inlet face 30a has a slightly convex upper portion 300a and a slightly concave lower portion 301a. The convex upper portion 300a has the effect of helping to focus the light intensity in the range of the produced light segment. The concave lower portion 301a has the effect of helping to spread the light down guide 3a and, therefore, in the upper part of the light segment produced 7a.

The light sources 1a-1d are mounted on a support inclined at the same angle θ relative to the vertical, facing the input faces 30a-30d.

The lower face 35a of the guide is here flat and inclined downwards so as to continuously widen the cross section of the guide 3a from its inlet 30a to its outlet 31a. Thus, the spreading of the rays generated by the concave portion 301a is not thwarted, these rays being able to propagate without interception.

On the Figures 9 and 10 the light guide 3a is shown. The other guides 3b-3d are analogous, with the only difference that the guide 3d has a left lateral face similar to that of the first embodiment as shown in FIG. figure 2 .

In the first two embodiments described, the corrective part 4 has a shape of half-ball or half-sphere. Other embodiments are possible.

In particular, in a third embodiment, the corrective part 4 has a slightly deformed half-ball shape, as shown in FIGS. Figures 11 and 12 .

The figure 11 represents a profile view in the direction XX 'of the optical module 2. The corrective part 4 comprises a lower portion 42 and an upper portion 43, separated by a horizontal plane P _h represented by a dashed line on the figure 11 . In the lower part 42, the radius of curvature of the outlet face 41 decreases progressively downwards, from the plane Ph, in order to gradually fold the spokes towards the optical axis 6, as shown in FIG. figure 11 . This is equivalent to gradually spreading the rays in the output plane of the guides. The rays spread in the bottom of the output plane of the guides have the effect of spreading the top of the light beam at the output of the optical module. This avoids a diaphragm effect from the bottom of the projection lens 5 which would produce by occultation a sudden cut of the top of the light beam.

The figure 12 represents a view from above in the direction ZZ 'of the optical module 2. The corrective part 4 comprises a left lateral part 44 and a right lateral part 45, separated by a vertical plane P _v , when the module 2 is observed in the direction YY '. In the left lateral part 44, the radius of curvature of the output face 41 of the corrective part 4 decreases gradually from the plane Pv to the left. This is equivalent to gradually spreading the rays in the output plane of the guides. The rays spread in the left part of the exit plane of the guides have the effect of spreading the right part of the light beam at the output of the optical module. This avoids a diaphragm effect by the left side of the projection lens 5 which would produce by occultation a sudden cut of the top of the light beam.

In a fourth embodiment, the corrective part 4 comprises an outlet front face 41 having a shape of spherical cap (that is to say a portion of sphere intersected by a plane other than median), connected to the exit plane guides 3a-3d by a rear portion of conical, cylindrical or other. The rear of the corrective portion 4 is connected to the outputs of the guides, located in the object focal plane of the projection lens 5, and further comprises, outside the connection areas of the guides, an optically inactive material-air interface. This material-air interface must be shaped not to be impacted by light rays coming out of the optical guides 3a-3d. The air interface portion of the rear of the corrective portion 4 may be adapted and shaped to function as a mechanical attachment zone.

Other alternative embodiments are possible. In particular, the various characteristics relating to the shapes of the faces of the guides and to the shape of the corrective part 4 can be used independently of one another or in combination for the manufacture of optical modules according to other embodiments. .

In the above description, the projection optical element is a lens. Alternatively, the lens could be replaced by any other projection optical element, capable of creating an infinite image of the outputs 31a-31d of the guides. This projection element could comprise one or more lenses, or one or more reflective mirrors, or a combination of mirror (s) and lens (s).

• le haut de la source de lumière secondaire à la sortie d'un guide correspond au bas du faisceau produit en sortie du module optique, et inversement ;
• la zone droite de la source de lumière secondaire à la sortie d'un guide correspond à la zone gauche du faisceau produit en sortie du module optique, et inversement.

In the foregoing description, the projection element has the effect of reversing the output of the guides:

• the top of the secondary light source at the output of a guide corresponds to the bottom of the beam produced at the output of the optical module, and vice versa;
• the right zone of the secondary light source at the output of a guide corresponds to the left zone of the beam produced at the output of the optical module, and vice versa.

In another embodiment, the projection element has no inversion effect. In this case, the shapes of the light guides 3a-3d and the corrective part 4 must be adapted according to the shape of the desired light beams at the output of the optical module.

The invention also relates to a motor vehicle headlight incorporating one or more optical lighting modules according to any one of the described embodiments.

Claims (21)

Primary optical element for a motor vehicle lighting module, comprising a plurality of light guides (3a-3d), characterized in that the light guides (3a-3d) are connected at the output to a corrective part (4) having an at least partly dome-shaped dome-shaped exit face (41), the light guides (3a-3d) and the correcting portion (4) forming a one-piece structure. Primary optical element according to claim 1, wherein the respective refractive indices of the light guides (3a-3d) and the corrective part (4) are substantially identical. Primary optical element according to one of claims 1 and 2, wherein the light guides (3a-3d) and the corrective part (4) are made of the same material. Primary optical element according to claim 3, wherein the light guides (3a-3d) and the corrective part (4) are derived from the same polymer. Primary optical element according to one of the preceding claims, wherein the substantially spherical dome-shaped outlet face (41) is centered substantially at the exit of one of the light guides (3b). Primary optical element according to one of the preceding claims, wherein the corrective part (4) has substantially the shape of a half-sphere. Primary optical element according to one of the preceding claims, wherein at least one light guide (3a-3d) has a face (34a-34d), upper or lower, having a cylindrical portion shape. Primary optical element according to one of the preceding claims, wherein the input face (30a) of at least one light guide (3a-3d) comprises a convex portion (300a). Primary optical element according to one of the preceding claims, wherein the input face (30a) of at least one light guide (3a-3d) has a concave portion (301 a). Primary optical element according to claim 8 or 9, characterized in that the input face (30a-30d) of said light guide (3a-3d) extends at least partially in a plane inclined with respect to the vertical of an angle between 0 ° and 45 °. The primary optical element of claim 10, wherein said plane is inclined at an angle of between 10 ° and 30 °. Primary optical element according to one of the preceding claims, characterized in that at least one light guide (3a-3d) comprises at least one spreading face (35a-35d, 33d), said spreading face being shaped so as to widen the cross section of the guide from its entrance face to its exit. Primary optical element according to the preceding claim, characterized in that the light guides (3a-3d) being juxtaposed two by two along a line, one of the two end guides of said line comprises a lateral face of spreading (33d). Primary optical element according to one of the preceding claims, characterized in that an area (42; 44) of the output face (41) of the corrective part (4) has a radius of curvature which decreases progressively. Primary optical element according to the preceding claim, characterized in that said area (42; 44) of the exit face (41) is a lateral zone, lower or upper. Optical assembly comprising the primary optical element (2) according to one of the preceding claims and a plurality of light sources (1a-1d), each source (1a-1d) being associated with a single guide (3a-3d). An assembly according to claim 16, wherein the light sources (1a-1d) are mounted on a support extending in a plane inclined to the vertical by an angle between 0 ° and 45 °. Assembly according to one of claims 16 and 17, wherein the distance between an input face (30a-30d) of a guide (3a-3d) and an output plane of the associated source is between 0.1 millimeters and 1 millimeter. Optical illumination module for a motor vehicle headlamp, characterized in that it comprises a plurality of light sources (1a-1d), a primary optical element (2) according to one of claims 1 to 15 and an optical element projection device (5), the outputs (31a-31d) of the guides (3a-3d) of the primary optical element being positioned in an object focal plane of the projection lens (5). Module according to claim 19, wherein the distance between the primary optical element (2) and the projection element (5) is strictly greater than zero. Motor vehicle headlight, characterized in that it comprises at least one optical module according to claim 19 or 20, including a plurality of optical modules according to claim 19 or 20.

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