EP3604904B1 - Light module comprising an array of light sources and a bifocal optical system - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a light module for a motor vehicle which is capable of projecting a light beam with horizontal contiguous segments and an angular resolution in vertical planes of less than 1 °.

BACKGROUND OF THE INVENTION

A motor vehicle is equipped with headlamps intended to produce a light beam which illuminates the road in front of the vehicle, in particular at night or in the event of reduced light.

Light modules of this type are already known. Such light modules are suitable for producing an illuminating light beam, for example a high beam, divided, vertically and horizontally, into light segments and of which at least some light segments can be selectively extinguished. This makes it possible, for example, to illuminate the road optimally while avoiding dazzling road users.

Such light modules generate segmented light beams, which are known by the English name of "pixel beam". It is for example possible to divide the overall light beam into a matrix of light segments.

Generally, the vertical resolution of the light beam, that is to say the number of light segments in the vertical planes of the beam emitted by a projector, remains quite coarse. Thus, the extinction of a light segment plunges into shadow a portion of the road which is often much wider than necessary to avoid dazzling a road user. It would be advantageous to be able to increase the vertical resolution of the light beam to be able to illuminate the road up to a road user located in front of the vehicle, while extinguishing the light segments liable to dazzle the road user.

These headlamps are preferably designed to illuminate a wide lateral visual field, but the known lighting systems have sometimes unsatisfactory visibility for the driver of the vehicle. In particular, it is difficult, if not impossible, to ensure a wide field of illumination in the horizontal plane of the path of the vehicle and at the same time to ensure high resolution in the vertical direction, and this for any angle in the horizontal plane. In addition, it is important to reduce the size of the projection lenses which should preferably have a smaller diameter of 80mm while using commercial light emitting diode arrays which each have a minimum size of 0.75mmx0.75mm. Furthermore, for reasons of visual comfort, as well as for regulatory reasons, it is preferable that two adjacent segments in the horizontal plane are contiguous so that the overall light beam illuminates the road in a homogeneous manner. However, the known solutions do not make it possible to obtain a high vertical resolution and at the same time to obtain a wide horizontal field having contiguous light segments, in particular when the light sources are too far apart from each other.

A known lighting system for a motor vehicle headlight, described in the document US 2014/0307459 A1 , comprises a primary optical module comprising a plurality of light sources, for example light emitting diodes, each associated with respective light guides. A secondary projection optical element, for example a lens, is associated with the primary optical module. This secondary optical projection element may have several focal lengths. Such a lighting system nevertheless has certain drawbacks. First, such a primary optical module, comprising a plurality of independent light guides each associated with a light source, is complex and expensive to produce. Also, the focal lengths are chosen to coincide with the exit surfaces of the primary optics. Also, this system requires positioning the primary optics at an angle relative to the optical axis of the projection element, which makes the alignment and assembly of the optical system complex and therefore expensive. The major drawback of such a system is that it is not possible to achieve vertical resolutions of less than 0.6 ° if standard commercial light sources and projection lenses having a large diameter, typically larger, are used. big than 100mm.

Another lighting system, described in the document DE102008013603 , relates to an optical module comprising a matrix of light emitters and makes it possible to project a homogeneous light beam. The system has an array of optical elements, each funnel-shaped. Each optical element in the array is positioned in front of an emitter and its reflective interior surface ensures that a substantially parallel beam is projected toward the projector. Such a matrix of reflective conical elements is expensive to manufacture. In addition, as the projection module described in the document US 2014/0307459 A1 , the system described in the document DE102008013603 does not provide a high vertical resolution associated with a high horizontal projection angle.

In another embodiment, described in the document US2015131305A a strip of light sources is suitable for a one-piece optical structure comprising a single light guide connected to a corrective optical part. The bifocal secondary optic, ensuring the projection of light in the far optical field, has a vertical focal plane which coincides with the exit surface of the optical guide, which of course produces low resolution in the vertical direction.

BRIEF SUMMARY OF THE INVENTION

• au moins un réseau de sources lumineuses, comportant m rangées transversales et n rangées verticales les rangées transversales étant disposées suivant une direction perpendiculaire aux rangées verticales, le nombre n étant plus élevé que le nombre m;
• au moins un dispositif bifocal d'imagerie conçu pour projeter un faisceau lumineux, le dispositif d'imagerie présentant une première surface de focalisation horizontale et une deuxième surface de focalisation verticale parallèle au dit premier plan;

caractérisé en ce que
le module lumineux comporte au moins un élément optique primaire, qui ne modifie pas en sortie selon une direction verticale V l'angle des rayons incidents, agencé pour transférer la lumière émise par les dites sources lumineuses sur une surface virtuelle de projection, définie entre le dit réseau et le dispositif d'imagerie, et confondue avec le premier plan de focalisation, de telle façon que les projections dans le plan horizontal des faisceaux émis par les dites sources lumineuses forment, dans la dite surface virtuelle de projection, des sources secondaires de lumière qui sont étirées dans la direction horizontale, et en ce que le deuxième plan de focalisation verticale est confondu avec la surface du réseau des sources lumineuses. Dans le plan horizontal, une dimension des sources secondaires de lumière est plus grande qu'une dimension des sources lumineuses et une ouverture angulaire des faisceaux secondaires de lumière émis par les sources de lumière secondaires est inférieure à une ouverture angulaire des faisceaux de lumière émis par les dites sources lumineuses.The invention provides a motor vehicle light module, defining a direction of movement (L), a vertical direction (V) and a horizontal direction (H) orthogonal to the vertical direction (V), the directions (L) and (V). ) defining a vertical plane and the directions (L) and (H) defining a horizontal plane comprising:

• at least one network of light sources, comprising m transverse rows and n vertical rows, the transverse rows being arranged in a direction perpendicular to the vertical rows, the number n being greater than the number m;
• at least one bifocal imaging device designed to project a light beam, the imaging device having a first horizontal focusing surface and a second vertical focusing surface parallel to said first plane;

characterized in that
the light module comprises at least one primary optical element, which does not modify at output in a vertical direction V the angle of the incident rays, arranged to transfer the light emitted by said light sources onto a virtual projection surface, defined between the said network and the imaging device, and coincides with the first focusing plane, such that the projections in the horizontal plane of the beams emitted by said light sources form, in said virtual projection surface, secondary sources of light which are stretched in the horizontal direction, and in that the second vertical focal plane coincides with the surface of the array of light sources. In the plan horizontal, a dimension of the secondary light sources is greater than a dimension of the light sources and an angular opening of the secondary light beams emitted by the secondary light sources is less than an angular opening of the light beams emitted by said sources bright.

The light module produced according to the teachings of the invention thus makes it possible to produce a light beam having a wide horizontal field of illumination while having a high angular resolution in any plane parallel to the vertical direction. Such a primary optical element is very easy to manufacture and robust as well as easy to assemble in a light module, therefore inexpensive to manufacture.

According to a first embodiment of the invention, the primary optical element is an array of cylindrical lenses. The longitudinal axis of each cylindrical lens is parallel to one of the vertical rows of light sources. Such an array of cylindrical lenses is easy and inexpensive to manufacture, for example by a plastic injection method.

In a preferable embodiment, the cylindrical lenses are designed to form, on the virtual projection surface, secondary light sources whose horizontal component is an M-factor magnification of the horizontal component of the light sources.

Advantageously, the magnification factor M is at least equal to 2.

Preferably, the cylindrical lenses are designed so that said secondary light sources are contiguous. This avoids obtaining projections of dark bands in the vertical direction.

Alternatively, the cylindrical lenses are designed so that said secondary light sources overlap partially in the horizontal direction. This makes it possible to obtain a homogeneous illumination field.

In another variant, the coverage of the secondary light sources in the horizontal direction is less than 20% of the width of their horizontal component.

According to a second embodiment of the invention, the primary optical element comprises an array of light guides arranged between said array of light sources and the imaging device. The use of light guides makes it possible to make the light emitted by the secondary sources more homogeneous.

Advantageously, the array of light guides consists of light guides having a first surface on the side of said array and a second surface, also defined as an exit surface, opposite to the first surface having, in any plane parallel to the horizontal direction, a width greater than the width of the first surface. This makes it possible to reduce, in any plane parallel to the horizontal direction, the angle of emission of the beams directed at the projection optic.

As a variant, the light guides have a trapezoidal shape in section parallel to the horizontal direction and a rectangular shape in any section defined in a vertical plane parallel to said grating. The manufacture of light guides having a trapezoidal section is easy and inexpensive and the surfaces can have very high optical quality.

In a variant, the light guides have in any horizontal plane a shape comprising curved side edges, ie their side faces are curved. The use of guides whose side walls are curved, preferably concave, makes it possible to improve the optical qualities of the beams emitted by the secondary sources. Faces curved lines as defined by polynomials can increase the number of possible optimizations of the light modulus.

Advantageously, said first surface is in close proximity to the light output surface of a light source of said vertical row. The immediate proximity has the advantage of guaranteeing a high efficiency of the transmission of the light emitted by the light sources towards the virtual projection plane. Advantageously, this virtual projection plane is coplanar with the exit surface of the light guides

In preferred variants, the width of the second surface has, in any section parallel to the horizontal plane, a dimension equal to or greater than twice the width of the first surface.

In an alternative embodiment, the primary optical element comprises diffractive optical elements. Using diffractive elements makes it possible to correct the intensity distributions emitted by the light sources and therefore to increase the optical quality of the beam. It is easy to integrate diffractive structures or refractive structures in molded parts or produced by plastic injection, without increasing the costs.

In alternative embodiments, n is at least equal to 10 and m is at least equal to 20. The use of networks comprising a large number of light sources makes it possible to considerably increase the angular resolution of the optical beam emitted by the device. imaging.

Advantageously, the angular opening of a light beam emitted by the light module coming from a single light source is less than 1 ° along the vertical axis.

In an alternative embodiment, the angular opening of a light beam emitted by the light module coming from a single light source is less than 0.6 ° along the vertical axis. This makes it possible to obtain a high vertical angular resolution.

Advantageously the vertical angular opening of the light beam emitted by the module, coming from all the light sources of the network, is at least equal to 2 °, preferably at least equal to 4 ° and at most 9 °
In an alternative embodiment, the horizontal angular opening of the light beam emitted by the module, coming from all the light sources of the array, is greater than 10 °, preferably greater than 20 °. This makes it possible to obtain a very large horizontal illumination field while ensuring high vertical resolution.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 est une vue de dessus qui représente un élément optique primaire et un élément optique secondaire d'un module lumineux réalisé selon le concept de l'invention ;
• la figure 2 est une vue de coté qui représente un élément optique primaire et un élément optique secondaire d'un module lumineux réalisé selon le concept de l'invention;
• la figure 3 est une vue en perspective qui représente un élément optique primaire comprenant un réseau de lentilles cylindriques et un élément optique secondaire d'un premier module lumineux, réalisés selon un premier mode de réalisation de l'invention;
• la figure 4 est une vue de dessus qui représente un élément optique primaire comprenant des guides de lumière et un élément optique secondaire d'un module lumineux, réalisés selon un deuxième mode de réalisation de l'invention ;
• la figure 5 est une vue de coté qui représente un élément optique primaire comprenant des guides de lumière et un élément optique secondaire d'un module lumineux, réalisés selon le deuxième mode de réalisation de l'invention;
• la figure 6 est une vue en perspective d'un guide de lumière ayant des parois verticales ou latérales planes ;
• la figure 7 est une vue en perspective d'un autre guide de lumière ayant des parois verticales ou latérales courbées ;
• la figure 8 est une vue de dessus d'un module lumineux comprenant un dispositif de projection réfléchissant;
• la figure 9 est une vue de dessus d'un module lumineux comprenant un dispositif de projection ayant une configuration de type Cassegrain ;
• la figure 10 est une vue de dessus d'un véhicule et d'un écran de projection situé devant le véhicule ;
• la figure 11 est une vue de côté d'un véhicule et d'un écran de projection situé devant le véhicule.

Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows, for the understanding of which reference is made to the appended drawings in which:

• the figure 1 is a top view which shows a primary optical element and a secondary optical element of a light module produced according to the concept of the invention;
• the figure 2 is a side view which shows a primary optical element and a secondary optical element of a light module produced according to the concept of the invention;
• the figure 3 is a perspective view which shows a primary optical element comprising an array of cylindrical lenses and a secondary optical element of a first light module, produced according to a first embodiment of the invention;
• the figure 4 is a top view which shows a primary optical element comprising light guides and a secondary optical element of a light module, produced according to a second embodiment of the invention;
• the figure 5 is a side view which shows a primary optical element comprising light guides and a secondary optical element of a light module, produced according to the second embodiment of the invention;
• the figure 6 is a perspective view of a light guide having flat vertical or side walls;
• the figure 7 is a perspective view of another light guide having curved vertical or side walls;
• the figure 8 is a top view of a light module comprising a reflective projection device;
• the figure 9 is a top view of a light module comprising a projection device having a Cassegrain type configuration;
• the figure 10 is a top view of a vehicle and a projection screen located in front of the vehicle;
• the figure 11 is a side view of a vehicle and a projection screen located in front of the vehicle.

DETAILED DESCRIPTION OF THE FIGURES

In the remainder of the description, longitudinal orientations, directed from rear to front, vertical, directed from bottom to top, and transverse, directed from left to right, indicated by the trihedron "L, V," will be adopted without limitation. T "of the figures.

The vertical orientation "V" is used as a geometric reference of the light module 10 unrelated to the direction of gravity.

The L and V directions define a vertical plane 32 and the L and H directions define a horizontal plane 34.

In the remainder of the description, elements having an identical structure or similar functions will be designated by the same references.

We have represented at the figure 1 and the figure 2 a horizontal cut ( figure 1 ) and a vertical section ( figure 2 ) a light module which is intended to equip a lighting or signaling device for a motor vehicle. The light module 10 is intended to emit a final light beam longitudinally towards the front of the vehicle. This is a light beam which is composed of a plurality of adjoining elementary beams. Such a light module 10 is in particular capable of fulfilling a lighting function having a large transverse angular opening and a large vertical angular resolution. Each elementary light beam illuminates a portion called hereafter “light segment”, also known under the term “pixel”. In the description, the term “vertical resolution” is understood to mean the angled size of each segment.

The light module 10 defines an optical axis O, parallel to the longitudinal orientation L, and comprises at least one network 12 of light sources 14, comprising m transverse rows 12A and n vertical rows 12B of light sources 14 which are in particular visible to figures 1, 2 , 3 , 4 and 5 . The transverse rows 12A are arranged in a direction perpendicular to the vertical rows 12B and the number n vertical rows 12B is greater than the number m transverse rows 12A.

Note that on figures 1 and 2 , the spacing proportions between the light sources 14 horizontally and vertically have not been respected; in fact, the vertical spacing between the sources is in reality tighter than the horizontal spacing.

Each light source 14 is formed by a light emitting source which is preferably, but not necessarily, a light emitting diode which has a light emitting diode. square or rectangular emission surface which extends in a plane substantially orthogonal to the optical axis O.

The array 12 of light sources 14 is carried by a support, preferably a printed circuit board 13. The light sources 14 can be switched on independently of one another, selectively, to obtain the desired illumination.

In a variant, the network 12 can be constituted by an assembly of several vertical arrays 12B of light sources 14, and each of the arrays may be carried by a support, preferably a printed circuit board. Each strip 12B carries the light sources forming one of the columns of the network 12.

Light sources 14 are closer to vertically adjacent light sources than transversely adjacent light sources. For example, two vertically adjacent light sources are spaced apart by a distance less than 10% of the vertical height of the emitting surface of said light source, while two transversely adjacent light sources are spaced apart by a distance greater than 10%. of the transverse width of the emission surface of said light source.

The light module 10 also comprises at least one primary optical element 40.

The primary optical element 40 is an optical part, or a set of parts and / or optical structures, arranged to transfer the light emitted by said light sources 14 onto a virtual projection surface 60, which is located opposite and to a predefined distance from the network 12, in the direction of the light emission. The figure 1 and the figure 2 illustrate a ray of light 16 emitted by a light source 14.

The virtual projection surface 60 is preferably a virtual plane, but can also be a virtual curved surface, defined for example in an embodiment where the support and / or the printed circuit 13 has a curved shape. As shown in the figure 1 , the primary optical element 40 is arranged such that the projections in the horizontal plane 34 of the light beams 16 emitted by said light sources 14 form, in said virtual projection surface 60, secondary light sources 62.

Advantageously, as illustrated in figure 1 , the optical element 40 is arranged so that, in the horizontal plane 34, the dimension of the secondary light sources 62 is greater than a dimension 14a of the light sources 14 and that the angular opening β of the secondary light beams 18 emitted by the secondary light sources 62 is less than an angular opening α of the light beams 16 emitted by said light sources 14. The principle used here, in any horizontal plane, is that of the Lagrange-Helmholz invariant which imposes that in an optical system nyα = y'α 'in which n and n' are the refractive indices of the object and image space respectively, y and y 'the object and image heights (or width) respectively, and α and a 'the angles of incident and emerging rays of an optical system. The figures 1 and 2 illustrate the propagation of a ray of light 16, 18, 20 having different angles with respect to the optical axis O.

The dimension of the cross section 62a of the secondary sources 62 is more particularly defined so that the secondary light sources 62 are contiguous or overlapping transversely.

In a nonlimiting exemplary embodiment, the dimension of the cross section 62a of the secondary sources 62 can be at least 2 times greater than the transverse dimension 14a of the light sources 14.

Of course, the primary optical element 40 can be arranged to present, in a horizontal plane, different enlargements M for different light sources 14 of the array. For example, the magnification M of a light source 14 present on the optical axis O may be smaller than the magnification of a light source 14 which is located at a transverse end of the array 12. This variant makes it possible to be applied in cases where the vertical rows 12B of the light sources 14 are not positioned evenly in the transverse direction.

Further, the primary optical element 40 is made to have no magnifying effect, or negligible magnifying effect, in the vertical direction, as shown in figure. figure 2 . This results in the fact that the primary optical element does not modify at the output in a vertical direction V the angle of the incident rays At most, the optical element can have a displacement effect, in the direction of the axis optical O, the conical beam of light emitted by the light sources 14, similar to the effect obtained by inserting a flat optical plate in an optical beam which passes through it. It is well known that this displacement depends on the thickness of the optical plate as well as its refractive index, which is also the case of the primary optical element 40.

Of course, the primary optical element 40 can be made in a single optical part but can include at least two optical parts which can have different shapes and / or refractive indices. Said at least two pieces can also be made of different materials and can include coatings to improve light transmission efficiency, such as an anti-reflective coating. In order to optimize the efficiency and the quality of the beam projected by the light module 10, the primary element 40 can comprise diffractive or refractive structures, such as diffraction gratings or Fresnel structures.

The light module 10 comprises at least one bifocal imaging device 30 which is designed to project a beam of light from each light source 14. The bifocal imaging device 30 preferably projects an image from each light source 14 to infinity, usually measured on a virtual reference plane, defined at a distance d _E with respect to the center of the bifocal imaging device 30. In the automotive field, this distance is typically 25 m, as illustrated in figures 10 and 11 .

The bifocal imaging device 30 may be an optical system having rotational symmetry relative to its optical axis O, but may also be an optical system which has a horizontal dimension greater than its vertical dimension.

In a preferred embodiment, the largest diameter of the bifocal imaging device 30 is less than 80mm.

The imaging device 30 has a first focal length F1 and a first transverse focusing surface 30a which is arranged substantially in coincidence with the virtual projection surface 60. In a preferred embodiment, the first focusing surface 30a is a planar virtual surface as illustrated in the FIGS. figures 1 to 5 . Thus, by projecting the secondary light sources 62 contiguous transversely, one thus obtains light segments contiguous transversely.

The imaging device 30 also has a second focal length F2 and a transverse focusing surface 30b which is arranged substantially in coincidence with the array 12 of the light sources 14. Of course, the focal length F2 is adapted to take account of the effect. deflection in the vertical plane of the primary optical element 40 as described above. Thus, by projecting the primary light sources which are extremely close vertically, one obtains light segments which are substantially vertically contiguous.

Thus, the total surface illuminated by the light module 10 has a dimension of approximately n times p1 in the horizontal direction and a dimension m times p ₂ in the vertical direction and the vertical angular resolution is thus p ₂ / d _E rad and the horizontal resolution p ₁ / d _E.

• une résolution angulaire horizontale ϕ de 0.6°; et
• une résolution angulaire verticale Y de 0.35°; et
• un nombre n de 15; et
• un nombre m de 25;

une surface illuminée de 5.2 m x 7.9m est réalisée sur un écran E positionné à 25 m du centre C. Dans cet exemple, à 25 m du module de lumière 10, la hauteur de chaque segment lumineux est d'environ 26cm sur l'écran E.Advantageously, the light module 10 of the invention can be configured, for all the embodiments, in order to obtain a horizontal angular resolution ϕ of less than 1 °, preferably less than 0.6 ° and a vertical angular resolution Y of less than 0.6 °, preferably less than 0.35 °. So, for example, with:

• a horizontal angular resolution ϕ of 0.6 °; and
• a vertical angular resolution Y of 0.35 °; and
• a number n of 15; and
• a number m of 25;

an illuminated surface of 5.2 mx 7.9 m is produced on a screen E positioned 25 m from the center C. In this example, 25 m from the light module 10, the height of each light segment is approximately 26cm on the screen E.

As illustrated in figures 10 and 11 the light module produces a beam having a horizontal angular opening Φ and a vertical angular opening θ. The horizontal angular opening Φ can be higher than 10 °, preferably higher than 20 °. The vertical opening θ can be higher than 2 °, preferably higher than 4 °. The various elements of the light module 10 can be adapted as a function of the desired total horizontal and vertical angle as well as of the horizontal and vertical angular resolution. Those skilled in the art will know how to add correction optical elements to the light modules 10 as a function of the nature of the light sources 14, their geometry and the spatial distribution of the beams of light. light emitted by these sources 14, as well as according to the type of the imaging device 30, and according to the type of the primary element 40 according to the invention, several embodiments of which are described in this document.

In one embodiment, the imaging device 30 has circular symmetry, relative to the optical axis O, and a diameter defined in a vertical plane is less than 100mm, preferably less than 80mm. In a variant, the vertical dimension of the device is different from its horizontal dimension. In this case, the largest diameter defined orthogonally to the optical axis is less than 100mm, preferably less than 80mm.

As illustrated in figures 8 and 9 , and described in detail for a few examples below, the imaging device 30 may comprise reflecting elements or be of the catadioptric type.

In one embodiment shown in figure 3 , the primary optical element 40 comprises an array of cylindrical lenses 42, each cylindrical lens 42 of which comprises a vertical axis C1 parallel to one of the vertical rows 12B of light sources 14. The array 40 of cylindrical lenses 42 comprises an entrance surface 42b of light and an exit surface 42a of light and forms an image, on the virtual projection surface 60. Preferably each ray of light emitted by a light source 14 is transferred by the array of cylindrical lenses 42 on the virtual surface of projection. projection 60.

The light distribution of this image consists of a horizontal row of vertically stretched light bands.

The cylindrical lenses 12 are arranged to form an enlarged image of the horizontal component 14a of the light sources 14 in the virtual projection plane 60. The magnification factor M, in a horizontal plane, obtained by the cylindrical lenses 12 is given by M = d2 / d1 where d1 is the distance between a light source 14 and the light entry surface 42b and d2 is the distance between the light emitting surface 42a and the virtual projection surface 60, as illustrated in figure 3 . In an exemplary embodiment, the magnification factor M is greater than 1.5, preferably greater than 2 or even more preferably greater than 5.

Preferably said light entry surface 42b is a transverse vertical planar surface. In a variant, the inlet surface 40a can also comprise a second array 40 of cylindrical lenses 42, which need not necessarily be symmetrical with the array 40 of cylindrical lenses 42 of the outlet surface 42a. In a variant, the array of cylindrical lenses may consist of two optical elements, each comprising a structure making it possible to achieve a focusing of light in a horizontal plane and without having a focusing effect in a vertical plane, apart from the effect. deflection of the incident beams and which is due, as already explained, to the thickness and the refractive index of the array of cylindrical lenses.

In one embodiment, the outlet surfaces 42a of the cylindrical lenses 42 have, in any horizontal plane 34, the shape of a section of a circle. In one variant, this form is defined by a polynomial.

Alternatively, diffractive structures can be arranged on the inlet surfaces 42b and / or the outlet surfaces 42a of the cylindrical lenses.

Those skilled in the art will know how to produce these lens arrays by known manufacturing methods, such as plastic molding, replication or even polymerization of polymers on an optical surface such as a glass surface.

In a variant, additional optical elements may be arranged between the array 12 of the light sources 14 and the array 40 of cylindrical lenses 42. These additional optical elements may for example comprise an array of microlenses, which may be useful in the case of certain types of light emitting diodes 14 which do not include an integrated collimating lens.

In one embodiment, the array of cylindrical lenses 42 is designed such that said secondary light sources 62 are contiguous, as illustrated in Figure 1. figure 1 .

In an alternative embodiment, the array of cylindrical lenses 42 is designed so that said secondary light sources 62 partially overlap in the horizontal direction H.

In an exemplary embodiment, the overlap, in the horizontal direction H, of the secondary sources is less than 20% of the width of their horizontal component 62a.

Of course, the optical elements of the light module can be optimized and arranged so that the distribution of the intensity of the image produced in the far field, for example at 25 m from the light module 10, is a homogeneous distribution, even if secondary sources partially overlap in the virtual projection surface 60.

In another embodiment, illustrated in figures 4, 5 , 6, 7 , the primary optical element 40 comprises an array 50 of light guides 52 disposed between the array 12, 12A, 12B of light sources 14 and the imaging device 30.

Said light guides 52 have a first surface 56 on the side of the array 12 of light sources 14 and a second surface 58, also defined as a light exit surface, opposite to the first surface 56, also defined as an entrance surface. from light. The first surface 56 and the second surface 58 are connected by vertical walls 51, 53 which are configured to modify, in a plane along the horizontal axis and relative to the optical axis O, the angle of propagation of a ray of light incident on these surfaces 51 , 53. The figures 4 and 5 show the propagation of a ray 16, 19, 21 respectively emitted by a light source 14, transmitted by a light guide 52 and projected by a bifocal imaging device 30.

In a preferred embodiment, said first surface 56 is in close proximity, or coincident, with the light exit surface 15 of a light source 14 of a vertical row 12B.

The light guide 52 also comprises an upper wall 57 and a lower wall 55 which are arranged such that no ray of light emitted by one of the vertical rows 12B of light sources is incident on these surfaces, as illustrated. in the figure 5 . The shape of the upper 57 and lower 55 surfaces may be planar or may be curved, as shown in the figures. figures 6 and 7 . In one embodiment, the upper 57 and lower 55 surfaces have no optical function and can therefore comprise at least one structure or a structuring making it possible to make the assembly of this light guide 52 in the light module 10 easy and therefore cheap. Those skilled in the art will know how to produce these structures directly in a mold of a light guide 52, made for example of injected plastic.

In one embodiment, the light guides 52 are made of a transparent solid material such as plastic or glass. In any section along the horizontal axis, the width of the first surface 56 is less than the width of the second surface 58. As illustrated in figure 4 , at least a portion of the light emitted by a light source 14 is refracted by the first surface 56 and undergoes at least a total reflection on one of the side walls 51, 53. These walls side 51, 53 can be flat or can be curved. The shape of the horizontal projection of the side walls 51, 53 may be defined by a polynomial, for example a parabolic shape or a portion shape of an ellipse or a hyperbolic shape. The figure 6 shows a perspective view of a light guide 52 which has side walls 51, 53 planar. The figure 7 shows a perspective view of a light guide 52 which has curved side walls 51, 53. In all cases, the side walls 51, 53 are configured so as to reduce the angle β of propagation, relative to the optical axis O, of a ray of light emitted by a light source 14. As shown in Figure figure 4 and 5 light guide 52 is positioned such that exit surface 58 is proximate to virtual projection surface 60. Alternatively, exit surface 58 coincides with virtual projection surface 60.

Similar to the embodiment of the figure 3 comprising an array of cylindrical lenses 42, the light guides 52 make it possible to produce secondary sources 60 which have a horizontal dimension greater than the horizontal width 14a of the light sources 14 and whose angle of propagation β of the light rays transmitted, relative to the optical axis O, is less than the angle of emission α of this ray of light by the source of emission 14 of this ray of light.

In a variant of the invention that is not shown, the light guides 52 are hollow and comprise a wall of which at least a portion of the vertical internal surfaces 51, 53 are reflective. In this case, the surfaces 56 and 58 are respectively a light inlet opening 56 and a light outlet opening 58. The magnifying optical effect obtained is similar to that of the light guides 52 made of a transparent material. described above. Indeed, the secondary emission source 62, which is present in the virtual projection surface 60, by the transfer of the light from a source 14 through the light guide 52, comprises a greater horizontal dimension than that of the light source 14. The advantage of a light guide 52 made with walls 51, 53 whose surfaces internal elements are reflective is to obtain better light transmission efficiency, especially since there is no loss of light by refraction through the inlet opening. On the other hand, reflective light guides are often more expensive to manufacture because they require in particular a reflective coating.

In a variant, illustrated in the figure 6 , the light guides 52 have a trapezoidal shape in any horizontal plane 34 and have a rectangular shape for any section defined in a vertical plane parallel to said network 12.

In an exemplary embodiment, the width of the second surface 58, for any section parallel to the horizontal plane 34, has a dimension equal to or greater than twice the width of the first surface 56.

In another exemplary embodiment, an axial dimension d _g of the light guides 52, defined in the optical axis O of the light module 10, is substantially identical to the dimension of the intersection of the first surface 46 with the horizontal plane 34 .

In yet another exemplary embodiment, an axial dimension d _g of the light guides 52, defined in the optical axis O of the light module 10, is at least 50% greater than the dimension of the intersection of the first surface 56 with the horizontal plane 34.

As shown in the figures 8 and 9 the imaging device 30 can include reflective elements R1, R2, R3. This makes it possible to realize light modules 10 which are shorter in the longitudinal direction L.

In one embodiment, a top view of which is shown in figure 8 , the imaging device 30 comprises at least one mirror R1 arranged in a so-called off-axis configuration. This configuration makes it possible to produce a light module of a defined length w, in the longitudinal direction, shorter than the variants illustrated in the figures 1, 2 , 3 , 4, 5 .

In another variant, a top view of which is shown in the figure 9 , the imaging device 30 is produced in a Cassegrain type configuration, comprising two mirrors R2, R3 also making it possible to produce light modules 10 that are more compact in the longitudinal direction.

In other variants of the invention not shown, catadioptric configurations can be implemented for the imaging device 30.

Claims (15)

1. Luminous motor-vehicle module (10), comprising:

   - at least one array (12) of light sources (14), comprising m transverse rows (12A) and n vertical rows (12B), the number n being higher than the number m;

   - at least one bifocal imaging device (30) designed to project a light beam, the imaging device (30) having a horizontal first focusing surface (30a) and a vertical second focusing surface (30b) parallel to said first surface;

   characterized in that
   the luminous module (10) comprises at least one primary optical element (40), which at its exit does not modify in a vertical direction V the angle of the incident rays, said primary optical element being arranged to transfer the light emitted by said light sources (14) to a virtual projecting surface (60) that is defined between said array (12) and the imaging device (30), and that is coincident with the first focusing surface (30a), in such a way that the projections in a plane containing a horizontal axis (H) of the beams (16) emitted by said light sources (14) form, on said virtual projecting surface (60), secondary light sources (62),
   and in that the vertical second focusing surface (30b) is coincident with the surface of the array of the light sources (14), and in that, in a horizontal plane (34), a transverse dimension of the secondary light sources (62) is larger than a transverse dimension of the light sources (14) and an angular aperture (β) of the secondary light beams (18) emitted by the secondary light sources (62) is smaller than an angular aperture (α) of the light beams (16) emitted by said light sources (14).
2. Luminous module (10) according to Claim 1, characterized in that the primary optical element (40) is an array of cylindrical lenses (42), and the longitudinal axis (C1) of each cylindrical lens (42) is parallel to one of the vertical rows (12B) of light sources (14).
3. Luminous module (10) according to Claim 2, characterized in that the cylindrical lenses (42) are designed to form, on the virtual projecting surface (60), secondary light sources (62) the horizontal component (62a) of which is an enlargement by a factor M of the horizontal component (14a) of the light sources (14).
4. Luminous module (10) according to Claim 3, characterized in that the enlargement factor M is at least equal to 2.
5. Luminous module (10) according to one of Claims 2 to 4, characterized in that the cylindrical lenses (42) are designed such that said secondary light sources (62) adjoin.
6. Luminous module (10) according to Claims 2 to 4, characterized in that the cylindrical lenses (42) are designed so that said secondary light sources (62) partially overlap in the horizontal direction (H).
7. Luminous module (10) according to Claim 6, characterized in that the overlap of the secondary light sources (62) in the horizontal direction (H) is smaller than 20% of the width of their horizontal component (62a) .
8. Luminous module (10) according to Claim 1, characterized in that the primary optical element (40) comprises an array (50) of light guides, said array being placed between said array (12, 12A, 12B) of light sources (14) and the imaging device (30).
9. Luminous module (10) according to Claim 8, characterized in that the array (50) of light guides is made up of light guides (52) having a first surface (56) on the side of said array (12) and a second surface (58) opposite to the first surface (56) having, in any plane containing the horizontal axis (34), a width larger than the width of the first surface (56).
10. Luminous module (10) according to Claim 9, characterized in that the light guides (52) have a trapezoidal shape in any plane containing the horizontal axis (34) and a rectangular shape in any cross section defined in a vertical plane parallel to said array (12).
11. Luminous module (10) according to Claim 10, characterized in that the light guides (52) comprise sidewalls (51, 53) having a curved shape in any plane containing the horizontal axis (34).
12. Luminous module (10) according to one of Claims 9 to 11, characterized in that said first surface (56) is in immediate proximity to the light exit surface (15) of a light source (14) of said vertical row (12B).
13. Luminous module (10) according to one of Claims 9 to 12, characterized in that, in any plane containing the horizontal axis (34), the width of the second surface (58) has a dimension equal to or larger than twice the width of the first surface (56).
14. Luminous module (10) according to one of Claims 1 to 13, characterized in that the primary optical element (40) comprises diffractive optical elements.
15. Luminous module (10) according to one of Claims 1 to 14, characterized in that n is at least equal to 10 and in that m is at least equal to 20.

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