EP3470728A1 - Light module for a motor vehicle - Google Patents

Abstract

The invention relates to a light module (22) of a motor vehicle comprising:
at least one matrix (24) of light sources (26) arranged in at least one horizontal line (32) and vertical columns (34), the light sources (26) being light emitting diode emitting surfaces which are all arranged on a common substrate (30);
at least one imaging device (28) designed to project the light sources (26), the imaging device (28) comprising at least a first object focal surface (40) having a curvature defect with a determined radius of curvature ;
characterized in that the substrate (30) has, in a horizontal plane, a curved shape parallel to the first object focal surface (40) of the imaging device (28).

The invention also relates to a projector equipped with at least one such light module.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to the technical field of lighting light modules for a motor vehicle.

• au moins une matrice de sources lumineuses rangées en au moins une ligne horizontales et en colonnes verticales, les sources lumineuses étant des surfaces émettrices de diodes électroluminescentes qui sont toutes agencées sur un substrat commun ;
• au moins un dispositif d'imagerie conçu pour projeter les sources lumineuses en un faisceau lumineux dans lequel chaque source lumineuse produit un pixel lumineux, l'activation des sources lumineuses d'une ligne formant une ligne lumineuse de pixels lumineux éclairée de manière homogène, le dispositif d'imagerie comportant au moins une première surface focale objet présentant un défaut de courbure de rayon de courbure déterminé.

The invention relates more particularly to a light module of a motor vehicle comprising:

• at least one matrix of light sources arranged in at least one horizontal line and in vertical columns, the light sources being light emitting diode emitting surfaces all of which are arranged on a common substrate;
• at least one imaging device designed to project the light sources into a light beam in which each light source produces a light pixel, the activation of the light sources of a line forming a light line of light pixels illuminated homogeneously, the imaging device comprising at least a first object focal surface having a defect of curvature of defined radius of curvature.

BACKGROUND ART OF THE INVENTION

Light modules of this type are already known. They are able to emit longitudinally forwards a segmented light beam. The illumination device comprises a matrix of elementary light sources which is projected forward by an imaging device to form the segmented light beam into a matrix of light pixels. Each bright pixel is illuminated by an associated light source. The light sources are likely to be activated in a individual and independent. By selectively switching on or off each of the elementary light sources, it is possible to create a light beam that specifically illuminates certain areas of the road in front of the vehicle, while leaving other areas in the dark.

Such an optical lighting module is used in particular to perform an adaptive lighting function also called "ADB", acronym for the English expression "Adaptive Driving Beam". 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 high beam mode by a projector, and to change the outline of this beam of light in such a way as to create a shadow zone at the location of the detected user while continuing to illuminate the road with a long-range beam on either side of the user. The advantages of the ADB function are multiple: comfort of use, better visibility compared to a lighting in dipped beam mode, risk of dazzling greatly reduced, driving safer ...

Such an optical module generally comprises a matrix of light sources, generally formed by light-emitting diodes (LEDs), and an imaging device. The light-emitting diodes are arranged on the surface of a planar substrate which extends in a plane orthogonal to the main emission direction of the light-emitting diodes. Each light source is imaged by the projection optics to form a light pixel. Each luminous pixel can be illuminated selectively by activation or deactivation of each light source.

Such an optical module is, however, likely to be subjected to optical aberrations such as spherical aberration, coma aberration, distortion aberration, astigmatism, field curvature aberration, etc.

The present invention relates more particularly to the resolution of the problems posed by the field curvature aberration also called "Petzval field curvature". Theoretically, the imaging device is assumed to have an object focal surface formed by a plane orthogonal to the optical axis of said optics. However, this object focal surface actually has a concave spherical curvature.

As a result, since the light sources of the matrix are arranged in a plane orthogonal to the optical axis of the projection optics, only the secondary elementary light sources located on the curved object focal surface are projected clearly. The other light sources situated in front of or behind the curved object focal surface will be projected in a more or less fuzzy manner according to their longitudinal distance with respect to the object focal surface. The further away the light source is from the object focal surface, the brighter the associated light pixel will be.

The matrix of light sources generally has a horizontal dimension much greater than its vertical direction. Thus, the light sources arranged at each end of a line are sufficiently far away from the object focal surface so that the curvature defect has visible effects on the corresponding luminous pixels. The defect of curvature thus has troublesome effects on the horizontal lines of luminous pixels, while the effects on the vertical columns of luminous pixels are hardly perceptible to the naked eye.

To solve this problem, it has already been proposed to interpose a primary optical element between the light sources and the imaging device. The primary optical element comprises for example light guides, each of which is associated with a light source. The exit faces of the light guides are arranged on a curved surface matching the curvature of the real object focal surface of the projection optics. The device imaging then projects an image of the exit faces of the light guides.

Since the light-emitting diodes are carried by a flat printed circuit board, the input faces of the light guides are arranged in the same plane. As a result, the light guides located transversely at a distance from the optical axis of the projection optics have a length greater than that of the light guides located near the optical axis. Such a primary optical element is not easy to manufacture because of the variable lengths of the light guides.

In addition, the length of the light guides at the ends of the primary optical element is such that the choice of material for producing the primary optical element is limited, for example, to silicone. It is particularly very complex and extremely expensive to make light guides polycarbonate or PMMA.

It has also been proposed to interpose an optical element for correcting the curvature of the field between the imaging device and the matrix of light sources.

However, such a solution imposes again to add an element to the light module. The manufacturing cost and the weight of the light module are then increased.

BRIEF SUMMARY OF THE INVENTION

• au moins une matrice de sources lumineuses rangées en au moins une ligne horizontales et en colonnes verticales, les sources lumineuses étant des surfaces émettrices de diodes électroluminescentes qui sont toutes agencées sur un substrat commun ;
• au moins un dispositif d'imagerie conçu pour projeter les sources lumineuses en un faisceau lumineux dans lequel chaque source lumineuse produit un pixel lumineux, l'activation des sources lumineuses d'une ligne formant une ligne lumineuse de pixels lumineux éclairée de manière homogène, le dispositif d'imagerie comportant au moins une première surface focale objet présentant un défaut de courbure de rayon de courbure déterminé ;
  caractérisé en ce que le substrat présente, dans un plan horizontal, une forme courbe au moins en partie parallèle ou confondue à la première surface focale objet du dispositif d'imagerie.

The invention proposes a light module of a motor vehicle comprising:

• at least one matrix of light sources arranged in at least one horizontal line and in vertical columns, the light sources being light emitting diode emitting surfaces all of which are arranged on a common substrate;
• at least one imaging device designed to project the light sources into a light beam in which each light source produces a light pixel, the activation of the light sources of a line forming a light line of light pixels illuminated homogeneously, the imaging device comprising at least a first object focal surface having a defect of curvature of defined radius of curvature;
  characterized in that the substrate has, in a horizontal plane, a curved shape at least partly parallel or merged with the first focal surface object of the imaging device.

Such a shape of the substrate makes it possible to arrange each light source of a line at a single distance from the first focussing surface object of the imaging device. As a result, the luminous pixels obtained by projection of the light sources of the same line have substantially the same light intensity profile regardless of their position along the line. In particular, a luminous pixel located at the end of the line will have substantially the same distribution of light intensity as a luminous pixel situated in the middle of the line.

According to another aspect of the invention, the substrate which carries the matrix of light sources is flexible at least in a horizontal plane to adapt its radius of curvature to the radius of curvature of the first object focal surface.

Flexible means that the substrate can be bent under stress and it resumes its original shape when the stress is removed. In particular, the substrate can take a flat shape in its unconstrained state.

It is thus possible to adapt the radius of curvature of the substrate to the radius of curvature of the first focusing surface object of the imaging device. This makes it possible in particular to use the same model of matrix of light sources with different imaging devices. This also makes it possible to perfectly adjust the radius of curvature of the matrix to each imaging device.

Alternatively, the substrate is also flexible in a vertical plane to form a sphere portion after deformation.

According to another aspect of the invention, the imaging device comprises an input face of the light rays, the imaging device being designed so that the first object focal surface has a determined radius of curvature so that, in projection in a horizontal plane, the circle virtually extending said first object focal surface passes through the end edges of the input face of the light rays.

This very advantageously makes it possible to improve the luminous efficiency of the light module by increasing the luminous flux of the light sources emitted by the light sources situated at the end of the line through the imaging device.

According to a variant of the invention, the light sources are merged with the first focal surface object of the imaging device.

This variant is particularly interesting when the light sources of the same line are substantially contiguous.

According to another aspect of the invention, the light sources are shifted rearwardly with respect to the first focal surface object of a specific offset distance.

For example, the offset distance is defined so that a cone whose base rests on the circumference of the input face of the imaging device and whose vertex is located on the intercepts focus, in the extension of its summit, a segment whose length is equal to the distance between the center of two consecutive light sources of the same line.

This makes it possible to improve the luminous homogeneity of the light beam emitted by the light module.

According to a first embodiment of the invention, the imaging device comprises a single object focal surface which is formed by said first object focal surface.

Such an imaging device is simpler to design.

According to a first variant of the first embodiment, the vertical distance separating two adjacent light sources of the same column is substantially equal to the horizontal distance separating two adjacent light sources of the same line so that, in the light beam, the Bright lines of bright pixels overlap vertically.

According to a second variant of the first embodiment, the vertical distance separating two adjacent light sources of the same column is greater than the horizontal distance separating two adjacent light sources of the same line so that, in the light beam, the lines bright luminous pixels appear distinctly from each other with vertical interposition of darker intervening lines.

According to this second variant, the invention also relates to a segmented light beam projector for a motor vehicle which comprises two light modules each produced according to the invention, the lines of light pixels of a light beam being interposed between the lines of light pixels. from the other light beam to create a homogeneous overall light beam.

According to a second embodiment of the invention, the imaging device comprises a second object focal surface, the first objective focal surface focusing the light rays in a horizontal plane, and the second object focusing surface focusing the light rays in a plane. vertical, the light module comprising a primary optical element which shapes the light rays emitted by the light sources to obtain vertically adjacent secondary light sources which are arranged in coincidence or near the second object focal surface.

This advantageously makes it possible to obtain a homogeneous light beam in which the light pixels also overlap vertically.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 est une vue de côté qui représente schématiquement un véhicule automobile équipé d'un module lumineux réalisé selon les enseignements de l'invention qui éclaire un écran transversal ;
• la figure 2 est une vue de face qui représente l'écran éclairé par le faisceau lumineux émis par le module lumineux de la figure 1 qui est segmenté en plusieurs pixels lumineux chevauchants ;
• la figure 3 est un diagramme qui représente le profil d'intensité lumineuse de trois pixels lumineux adjacents du faisceau lumineux en fonction de leur position sur un axe transversal de l'écran ;
• la figure 4 est une vue en perspective qui représente schématiquement le module lumineux réalisé selon un premier mode de réalisation de l'invention ;
• la figure 5 est une vue de face qui représente une matrice de sources lumineuses qui équipe le module lumineux de la figure 4 ;
• la figure 6 est une vue en coupe longitudinale transversale selon le plan de coupe 6-6 de la figure 4 qui représente le substrat courbé de la matrice de sources lumineuses ainsi que la première surface de focalisation objet d'un dispositif d'imagerie du module lumineux ;
• la figure 7 est une vue similaire à celle de la figure 6 qui représente une variante de réalisation de l'invention dans lequel la première surface de focalisation a été prolongée par un cercle passant par des bords d'extrémité de la surface d'entrée du dispositif d'imagerie ;
• la figure 8 est une vue en coupe verticale longitudinale selon le plan de coupe 8-8 de la figure 4 ;
• la figure 9 est une vue de face similaire à celle de la figure 2 dans laquelle l'écran est éclairé par un projecteur comportant deux modules lumineux réalisés selon une variante du premier mode de réalisation de l'invention ;
• la figure 10 est une vue en coupe longitudinale transversale qui représente schématiquement le projecteur comportant les deux modules qui éclairent l'écran de la figure 9 ;
• la figure 11 est une vue similaire à celle de la figure 6 qui représente un module lumineux réalisé selon un deuxième mode de réalisation de l'invention dans lequel il comporte un élément optique primaire et dans lequel le dispositif d'imagerie comporte deux surfaces de focalisation objet distinctes ;
• la figure 12 est une vue similaire à celle de la figure 8 qui représente le module lumineux réalisé selon le deuxième mode de réalisation de l'invention ;
• la figure 13 est une vue similaire à celle de la figure 12 qui représente une variante du deuxième mode de réalisation de l'invention.

Other features and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

• the figure 1 is a side view which schematically shows a motor vehicle equipped with a light module made according to the teachings of the invention which illuminates a transverse screen;
• the figure 2 is a front view which represents the screen illuminated by the light beam emitted by the light module of the figure 1 which is segmented into several overlapping luminous pixels;
• the figure 3 is a diagram that represents the light intensity profile of three adjacent luminous pixels of the light beam as a function of their position on a transverse axis of the screen;
• the figure 4 is a perspective view which shows schematically the light module made according to a first embodiment of the invention;
• the figure 5 is a front view that represents a matrix of light sources that equips the light module of the figure 4 ;
• the figure 6 is a transverse longitudinal sectional view along the section plane 6-6 of the figure 4 which represents the curved substrate of the matrix of light sources as well as the first focussing surface object of an imaging device of the light module;
• the figure 7 is a view similar to that of the figure 6 which represents an alternative embodiment of the invention in which the first focusing surface has been extended by a circle passing through end edges of the input surface of the imaging device;
• the figure 8 is a longitudinal vertical sectional view along the section plane 8-8 of the figure 4 ;
• the figure 9 is a front view similar to that of the figure 2 wherein the screen is illuminated by a projector having two light modules made according to a variant of the first embodiment of the invention;
• the figure 10 is a transverse longitudinal sectional view which shows schematically the projector comprising the two modules which illuminate the screen of the figure 9 ;
• the figure 11 is a view similar to that of the figure 6 which represents a light module made according to a second embodiment of the invention in which it comprises a primary optical element and wherein the imaging device comprises two distinct object focusing surfaces;
• the figure 12 is a view similar to that of the figure 8 which represents the light module produced according to the second embodiment of the invention;
• the figure 13 is a view similar to that of the figure 12 which represents a variant of the second embodiment of the invention.

DETAILED DESCRIPTION OF THE FIGURES

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

In the remainder of the description, there will be adopted without limitation a local coordinate system linked to the light module having longitudinal orientations, oriented from rear to front and corresponding to the normal direction of movement of the vehicle, vertical, oriented from bottom to top, and transverse, oriented from left to right indicated by the trihedron "L, V, T" of the figures. The vertical orientation is used here as a geometric reference for the description of the light module, unrelated to the direction of gravity.

In addition, the vertical and transverse orientations are independent of a reference linked to the vehicle. By way of non-limiting example, in the example of figure 1 , the transverse orientation extends from one wing to the other of the vehicle parallel to the road, while the vertical orientation extends orthogonally to the road, from the wheels to the roof of the vehicle. Nevertheless, it will be understood that the light module can also be arranged in the vehicle so that the vertical and transverse orientations are rotated about the longitudinal axis relative to the vehicle.

We have shown figure 1 a motor vehicle 10 equipped with a projector 12 which produces a light beam 14 segmented into light pixels which performs a specific lighting function. Without limitation, this is a high beam function. The light beam 14 is emitted along a substantially longitudinal transmission axis "A" toward the front of the vehicle 10.

For the purposes of the description, a vertical transverse screen 16 has been arranged at a determined longitudinal distance in front of the vehicle 10. The screen 16 is here arranged at 25 m from the vehicle.

As represented in figure 2 a transverse axis "H" and a vertical axis "V" intersecting at the axis "A" of emission of the light beam 14 have been drawn on the screen 16. The axes "H" and "V" are graduated in degree of opening of the light beam.

The light beam 14 illuminates an area 18 of the screen 16. This illuminated area 18 is divided into a matrix of juxtaposed light pixels 20 which are arranged in transverse lines and in vertical columns. The bright pixels 20 are individually activatable and independently of each other.

The term "juxtaposed" means that two adjacent bright pixels 20 vertically or transversely overlap each other. Thus, when all the light pixels 26 are lit, the light beam 14 substantially homogeneously illuminates the area 18 of the screen 16. When a light pixel 20 is off, a portion of the space it occupies on the Screen 16 is not lit by neighboring pixels.

More particularly, each light pixel 20 has a bell-shaped light intensity profile along a section line. The overlap of two luminous pixels 20 is defined by the fact that the light profiles of two successive luminous pixels along a line, for example transverse, intersect.

The figure 3 gives a non-limiting example of overlapping luminous pixels 20. The figure 3 represents the light intensity profiles of three adjacent 20A, 20B, 20C light pixels projected onto the screen 16. Each light pixel 20A, 20B, 20C has a bell-shaped light intensity profile, the maximum light intensity Imax being located in the center of the light pixel 20A, 20B, 20C. As can be seen, the left light pixel 20A overlaps the central light pixel 20B so that the light intensity curves intersect at a "P1" point having a luminous intensity substantially equal to half of the maximum luminous intensity Imax. Similarly, the right light pixel 20C overlaps the central light pixel 20B so that the light intensity curves intersect at a point "P2" having a light intensity substantially equal to half the maximum light intensity Imax. A central band comprising the top of the bell is illuminated only by the central light pixel 20B, and this central band is surrounded by degraded and low intensity light bands, which extend from the central band respectively to the points P1. and P2.

In a non-illustrated variant of the invention, each luminous pixel has a luminous profile approaching a slot shape in which the top of the bell is spread out to substantially form a plate. In this case, the crossing between two light intensity profiles of two successive luminous pixels is at a light intensity less than half of the maximum intensity.

According to another variant not shown of the invention, for example when the light sources are projected in a fuzzy manner, the space occupied by a given light pixel is likely to be fully illuminated by the adjacent luminous pixels. In this case, to obtain a completely dark area, it is necessary to turn off at least two adjacent pixels.

To achieve such a light beam 14, the projector 12 comprises at least one light module 22. As shown for example in FIG. figure 4 , the light module 22 comprises at least one matrix 24 of light sources 26 and at least one imaging device 28 which is designed to project the light sources forming the light beam 14 in which each light source 26 produces a light pixel 20. The light sources 26 are here all identical in size.

More particularly, the light sources 26 are formed by light-emitting diode-emitting surfaces. They are all arranged on a front face 29 of a common substrate 30. The common substrate 30 has a plate shape which extends in a generally vertical transverse plane

More particularly, all the light sources 26 are arranged in the same plane parallel to or coincident with the face 29. For example, if the light emitting diodes protrude from the face 29, they all project from the same distance.

The light sources 26 are arranged in horizontal lines 32 and in vertical columns 34. The matrix 24 here has a greater number of columns 34 than 32 lines. As a result, the matrix has a transverse width much greater than its vertical height.

In the embodiment shown at figure 5 two adjacent light sources 26 of the same line 32 are spaced apart by a first transverse distance "D1". Here, the transverse distance "D1" is the same for all the light sources 26 of the same line 32.

Similarly, two adjacent light sources 26 of the same column 34 are spaced apart by a second vertical distance "D2". Here, the vertical distance "D2" is the same for all light sources of the same column 34.

The light module 22 comprises at least one imaging device 28 which is designed to project an image of each light source 26 substantially to infinity. The imaging device 28 is especially designed to project the light sources 26 by forming the light beam 14 in which each light source 26 produces a light pixel 20.

In the embodiments shown in the figures, the imaging device 28 is in the form of a single lens. It will be understood, however, that the imaging device may also comprise at least one reflecting element and / or one or more lenses.

In general, the imaging device 28 has an input face 36 of the light rays and an output face 38 of the light beam 14.

The imaging device 28 has at least a first focal length F1 and a first generally transverse vertical object focal surface 40 which is arranged substantially in coincidence with the light sources 26.

The first object focal surface 40 is arranged in such a way that, when all the light sources 26 of a line 32 are activated, the screen 16 is illuminated homogeneously by a corresponding luminous line of light pixels 20.

In current use, the object focal surface 40 of the imaging device 30 is represented in first approximation by an objective focal surface 40 which is plane and perfectly orthogonal to the optical "A" axis. However, in reality, it is known that the projection optic 14 has an object focal surface having a concave spherical curvature defect. Such a defect is called Petzval field aberration. The curvature defect has a radius of curvature of radii of curvature determined. Thus, as represented for example in the figure 6 , in sectional view according to a horizontal section plane, the first object focal surface 40 appears as a circular arc.

For the luminous pixels 20 of the same line to have a uniform sharpness, the invention proposes that the substrate 30 of the matrix 24 has, in a horizontal plane, a curved shape at least partly parallel to the first focal surface object 40 of the imaging device 28. In particular, the portion of the substrate 30 comprising the light sources 26 may have, in a horizontal plane, a curved shape parallel to the first object focal surface 40 of the imaging device 28 while the ends of the substrate 30 located on either side of the portion of the substrate 30 comprising the light sources 26 may have, in this same horizontal plane, a shape parallel or not to the first object focal surface 40 of the imaging device 28.

According to an example shown in figure 6 , the entire substrate 30 of the matrix 24 has, in a horizontal plane, a curved shape parallel to the first object focal length 40 of the imaging device.

The substrate 30 is thus curved so that its front face 29 has a cylindrical sector shape of vertical generatrices and direction in a horizontal arc. The radius of curvature of the substrate 30 is determined so that each line 32 of light sources 26 is parallel to the object focal surface 40 taken along a horizontal sectional plane passing through said line 32. Thus, all the light sources 26 of a same line 32 are arranged at the same distance from the first object focal surface 40.

Advantageously, the substrate 30 carrying the matrix 24 of light sources 26 is flexible at least in a horizontal plane to precisely adapt its radius of curvature to the radius of curvature of the first object focal surface 40. The substrate 30 is for example elastically flexible, the front face 29 of the substrate 30 having a planar shape in its unstressed state, as shown in broken lines at the figure 6 . This makes it possible to precisely adjust the radius of curvature of the substrate 30 to the defect of curvature of the associated imaging device 30.

In practice, the die 24 is mounted on a frame which makes it possible to adjust its radius of curvature. The frame comprises for example two clamping jaws 35 which are each arranged against a vertical edge of the substrate 30 and transversely clamping the substrate 30 to constrain it to the desired curved position.

In a variant not shown, the frame has a curved bearing surface against which a rear face of the substrate 30 is fixed, for example by gluing or elastic interlocking or by any other suitable fastening means.

When the transverse distance "D1" between two adjacent light sources 26 of the same line 32 is substantially zero, it is possible to perfectly coincide the first object focal surface 40 with the light sources to obtain a uniform illumination of a line corresponding 20 bright pixels. The light sources 26 are thus merged with the first objective focal surface 40 of the imaging device 28.

Generally, the transverse distance "D1" between two adjacent light sources 26 of the same line 32 is not zero. For example, the transverse distance "D1" is between 10% and 50% of the width of a light source 26. In order to obtain a uniform illumination of the screen 16 by the corresponding line of light pixels 20, the surface focal length object 40 is shifted longitudinally forward a longitudinal distance "D3" with respect to the nearest light sources 26, as shown in FIG. figure 6 . This allows the light source 26 to be imaged by a slightly blurred and more transversely spreading light pixel 20 which overlaps the adjacent pixels 20, thereby removing the dark spaces between two transversely adjacent light sources 26. In this case, the radius of curvature of the substrate 30 is equal to the sum of the radius of curvature of the first object focal surface 40 and the longitudinal distance "D3" of offset.

In the embodiment shown at figure 6 , the offset distance "D3" is defined so that a cone 43 whose base is supported on the circumference of the input face 36 of the imaging device 28 and whose apex is located on the focus of the device In the extension of its apex, the imaging circuit 28 intercepts a segment whose length is equal to the distance between the center of two consecutive light sources 26 of the same line 32. It will be noted that the opening angle "α of the cone 43 corresponds to the opening angle of the imaging device 28.

According to another aspect of the invention, a virtual "C" circle is defined which is formed by extending the first object focal plane 40. The imaging device 28 is advantageously designed so that the first object focal plane 40, projected into an axial horizontal plane, has a radius of curvature determined so that the circle "C" passes through the end edges of the input face 36 of the light rays, as illustrated in FIG. figure 7 . Thus, the end edges of the input face 36 define an arc 41 of the circle "C". The so-called "inscribed angle" theorem states that an angle inscribed in the circle "C" which intercepts said arc 41 has the same value "α" regardless of the position of its vertex on the circle "C". The angle "α" corresponds to the opening angle of the imaging device 28.

In optical terms, and in the context of the invention, this means that the luminous flux produced by a light source 26, arranged near the first object focal surface 30, passing through the input face 36 of the imaging device 28 is substantially identical for all the light sources 26 of said line 32. This configuration thus makes it possible to very substantially improve the light output of the light sources 26 arranged at the end of line 32 with respect to a light module in which the light sources are arranged on a plane substrate. This configuration also avoids vignetting optical aberrations.

According to a first embodiment of the invention which is described with reference to figures 4 , 6 , 7 and 8 the imaging device 28 has a single object focal surface which is formed by said first object focal surface 40.

The matrix 24 of light sources 26 is designed so that the vertical distance "D2" separating two adjacent light sources 26 of the same column 34 is substantially equal to the horizontal distance "D1" separating two adjacent light sources 26 of the same line 32. Thus, the light beam 14 illuminates the screen 16 so that the light lines of light pixels 20 overlap vertically, in the same way as two light pixels 20 of the same line 32. The light beam 14 thus illuminates homogeneous screen 16.

As shown in figure 8 when the substrate 30 is flexible in only one plane, the die 24 has, in vertical axial section, a rectilinear shape, while the first object focal surface 40 has a shape of an arc of a circle. However, this configuration is not a problem since, as explained above, the vertical dimension of the matrix 24 is much smaller than its transverse dimension. As a result, the blur created by the effect of the curvature of the field is not perceptible to the naked eye on the luminous pixels 20 of the same column.

However, it is not always easy to obtain a matrix 24 having light sources that are as close together vertically.

To solve this problem, the invention proposes a variant of this first embodiment which is represented in FIGS. figures 9 and 10 . The vertical distance "D2" separating two adjacent light sources 26 of the same column 34 is greater than the horizontal distance "D1" separating two sources adjacent luminaires 26 of the same line 32 so that, in the light beam 14A, the lines 42A of bright pixels 20 appear distinctly from each other with the interposition of darker interposed lines, as shown in FIG. figure 9 .

To allow a uniform illumination of the screen 16, the projector 12 then comprises two light modules 22A, 22B similar. The second light module 22B is arranged to project a light beam 14B having lines 42B of light pixels 20 between the lines 42A of light pixels of the other light beam 14A to create a homogeneous overall light beam.

The two light modules 22A, 22B are here arranged in the same projector 12. The projector 12 comprises a housing 44 common closed by an ice 46 enclosing the two light modules 22A, 22B.

As a variant, to solve the problem posed when the vertical distance "D2" between the light sources 26 of the matrix 24 is too great, the invention proposes a second embodiment of the invention which is represented in FIGS. figures 11 and 12 .

In this embodiment, the imaging device 28 is a bifocal device, sometimes also called astigmatism, which comprises, besides the first object focal surface 40, a second object focal surface 48. The second object focal surface 48 is arranged at a focal length "F2" with respect to the optical center of the imaging device 28.

The first object focal surface 40 focuses the light rays in a horizontal plane, while the second object focal surface 48 focuses the light rays in a vertical plane.

The light module further comprises a primary optical element 50 which shapes the light rays emitted by the light sources 26 to obtain light sources. vertically adjoining secondary members which are arranged on the second object focal surface.

The primary optical element 50 is an optical part, or a set of parts and / or optical structures, arranged to transfer the light emitted by said light sources 26 onto a virtual projection surface, which is opposite and at a distance predefined of the matrix 24, in the direction of the emission of light, to form the secondary light sources 52.

In the example shown in figure 12 the virtual surface is advantageously a virtual concave surface in the form of a parallel sphere portion or coincident with the second object focusing surface 48.

In a variant, the virtual projection surface may be a cylinder portion parallel to the front face of the matrix 24.

Advantageously, each secondary light source 52 has a height greater than that of each associated light source 26. Thus, the secondary light sources 52 are here joined vertically.

Of course, the primary optical element 50 may be made in a single optical part but may comprise at least two optical parts which may have different shapes and / or refractive indices. The at least two pieces may also be made of different materials and may include coatings for improving light transmission efficiency, such as an antireflection coating. In order to optimize the efficiency and the quality of the beam projected by the light module, the primary element 50 may comprise diffractive or refractive structures, such as diffraction gratings or Fresnel structures.

In the embodiment shown in figures 11 and 12 , the primary optical element 50 comprises several layers of light guide 54 each of which is arranged facing a line 32 of associated light sources 26.

A guide sheet 54 is defined as an optical part capable of guiding light by total internal reflection of this light, for example from an entrance face to an exit face. A guide sheet 54 has a small thickness compared to its length and its width.

Thus each guide ply 54 has an upper face 56 and an underside 58 of extended guide separated by a periphery. This circumference defines a thickness of the guide ply 56, which may be variable, for example increasing from one end to the other. The periphery comprises a vertical rear transverse face 60 input of light common to all light sources 26 of the associated line 32. The rear face 60 input is arranged near the associated light sources 26, for example a few millimeters.

The light emitted by the light sources 26 which enters through the rear face 60 propagates inside the guide ply 60 by successive total internal reflections against the upper and lower faces 56, 58 towards a front transverse face 62 vertical exit. The front face 62 forms a portion of the periphery of the guide ply 54.

In the embodiment shown in the figures, the outlet face 62 of each guide ply 54 has a height greater than that of its inlet face 60. As a result, each guide ply 54 has, in transverse longitudinal section, a profile diverging from its inlet face 60 to its outlet face 62.

The input face 60 has a height that is substantially equal to the height of the emission surface of the associated light sources 26.

The exit face 62 is thus illuminated over its entire height by the associated light sources 26, thus forming a line of secondary light sources 52.

The first object focusing surface 40 of the imaging device 28 is arranged in the same manner as in the previous embodiments, that is to say in coincidence or near the light sources 26. The second focussing surface object 48 which is arranged substantially in coincidence with the outlet faces 62 of the guide plies 54.

Thus, for each light source 26 arranged substantially close to the first object focusing surface 40, the light rays emitted by the emission surface of said light source 14 are projected parallel by the imaging device 28 in vertical planes. longitudinal, so that the light beam associated with said light source 26 creates a light segment of generally rectangular shape transversely delimited by vertical edges which are the sharp image of the vertical edges of the emission surface.

Similarly, each light source 26 creates on the output face 62 of the guide web 20 a secondary light source 52. Each secondary light source 52 is thus delimited vertically by two transverse edges which coincide with the edges formed by the upper faces and lower 56, 58 with the outlet face 62.

Since the outlet face 62 is arranged substantially in coincidence with the second object focusing surface 48, the light rays emitted by each secondary light source 52 are thus projected parallel by the imaging device 28 in longitudinal transverse planes, so that the light beam associated with said light source 20 creates a luminous segment of generally rectangular shape delimited vertically by vertical edges which are the image clear of the transverse edges of the secondary light source 52.

The secondary light sources 52 being substantially contiguous, the pixels 20 obtained are also vertically joined.

For the same reasons of homogeneity of the light beam 14, it may be possible to slightly shift the second object focal surface 48 forward with respect to the secondary light sources 52 to obtain light pixels 20 which overlap slightly vertically, in the sense explained above.

As a variant of the invention shown in figure 13 the guide web is replaced by reflective surfaces. In this case, the space that was occupied by the guide web of the figure 12 is left empty, while the reflective surfaces are carried by prisms 64 which extend longitudinally from their base 66 located on the front face of the substrate 24, between two lines 32 to a free front transverse edge 68. The upper faces 58 and lower 56 of the prisms 64 form reflecting surfaces. The prisms fill exactly the gaps between two guiding layers of the figure 12 . This embodiment operates in the same way as the embodiment of the figure 12 and it provides the same benefits.

Thanks to the light module made according to any of the embodiments described above, the pixels obtained are sharper, particularly on the transverse edges of the area illuminated by the light beam.

In addition, when the imaging device designed according to the other aspect of the invention so that the virtual sphere carrying the objective focusing surface passes through the edges of its input face, the light output of the module light is substantially improved compared to known designs.

Claims (11)

A light module (22) for a motor vehicle comprising: at least one matrix (24) of light sources (26) arranged in at least one horizontal line (32) and vertical columns (34), the light sources (26) being light emitting diode emitting surfaces which are all arranged on a common substrate (30); at least one imaging device (28) designed to project the light sources (26) into a light beam (14) in which each light source (26) produces a light pixel (20), the activation of the light sources ( 26) of a line (32) forming a homogeneously illuminated light pixel light line (20), the imaging device (28) having at least a first object focal surface (40) having a radius curvature defect determined curvature;
characterized in that the substrate (30) has, in a horizontal plane, a curved shape at least partly parallel or merged with the first object focal surface (40) of the imaging device (28). Light module (22) according to the preceding claim, characterized in that the substrate (30) which carries the matrix (24) of light sources (26) is flexible at least in a horizontal plane to adapt its radius of curvature to the radius of curvature of the first object focal surface (40). Light module (22) according to any one of the preceding claims, characterized in that the imaging device (28) has an input face (36) of light rays, the imaging device (28) being designed to that the first object focal surface (40) has a radius of curvature determined so that, in projection in a horizontal plane, the circle (C) virtually extends said first surface object focal length (40) passes through the end edges of the input face (36) of the light rays. Light module (22) according to any one of the preceding claims, characterized in that the light sources (26) coincide with the first object focal surface (40) of the imaging device. Light module (22) according to any one of claims 1 to 3, characterized in that the light sources (26) are offset rearwardly with respect to the first object focal surface (40) by a determined offset distance . Light module (22) according to the preceding claim, characterized in that the offset distance (D3) is defined so that a cone (43) whose base rests on the circumference of the input face (36) of the imaging device (28) and whose apex is located on the focus intercepts, in the extension of its apex, a segment whose length is equal to the distance between the center of two consecutive light sources (26) of a same line (32). The light module (22) according to any one of the preceding claims, characterized in that the imaging device (28) has a single object focal surface (40) which is formed by said first object focal surface (40). Light module (22) according to the preceding claim, characterized in that the vertical distance (D2) separating two adjacent light sources (26) of the same column (34) is substantially equal to the horizontal distance (D1) separating two light sources (26) adjacent the same line (32) so that, in the light beam (14), the light lines of light pixels (20) overlap vertically. Light module (22) according to claim 7, characterized in that the vertical distance (D2) separating two adjacent light sources (26) of the same column (34) is greater than the horizontal distance (D1) separating two adjacent light sources (26) of the same line (32) so that in the light beam (14) the light lines of light pixels (20) appear distinctly one from the other. others with vertical interposition of darker interlayers. Light module (22) according to any one of claims 1 to 6, characterized in that the imaging device (28) comprises a second object focal surface (48), the first object focal surface (42) focusing the light rays in a horizontal plane, and the second object focal surface (48) focusing the light rays in a vertical plane, the light module (22) having a primary optical element (50) which shapes the light rays emitted by the light sources ( 20) to obtain vertically adjacent secondary light sources (52) which are arranged in coincidence or near the second object focal surface (48). Light beam projector (12) for a motor vehicle, characterized in that it comprises two light modules (22A, 22B) each made according to claim 8, the lines of light pixels (20) of a beam light beam (14A) being interposed between the light pixel lines (20) of the other light beam (14B) to create a homogeneous overall light beam.

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