Microlens array and lighting module for a motor vehicle

Abstract

The invention relates to an array (1) of microlenses (10) for a motor vehicle lighting module (2), wherein the array (1) of microlenses (10) is configured to shape light rays (RL) generated by a light source (22) in order to generate a projection beam (FP), wherein the array (1) of microlenses (10) comprises entrance lenses (101) that form an entrance face (104) of the array (1) of microlenses (10), and exit lenses (102) that form an exit face (105) of the array (1) of microlenses (10), and wherein the entrance lenses (101) and the exit lenses (102) form, in pairs, an optical channel (103) configured to project an image (IM) of the light source (22). A modulated face (11) of the array (1) of microlenses (10) has a modulated surface which is superimposed over a base conformation of the modulated face (11), so as to create a gradual decrease in light intensity at the peripheral edges of the image (IM) thus projected.

Description

Description Title of the invention: microlens array and light module for motor vehicle [1] The technical context of the present invention is that of lighting devices for motor vehicles. More particularly, the invention relates to a microlens matrix and to a light module for a motor vehicle comprising such a microlens matrix. [2] In the state of the art, the use of light modules for motor vehicle lighting devices is known for shaping a headlight beam used as a main beam or as a dipped beam to illuminate a road scene located in front of the motor vehicle. Such known light modules comprise: - at least one light source configured to generate light rays; - a microlens array comprising input lenses forming an input face of the microlens array and output lenses forming an output face of the microlens array, each input lens being coupled to the output lens located opposite via an optical channel, the microlens array being configured to shape the light rays generated by the at least one light source in order to generate a projection beam; - a plurality of collimators optically coupling the at least one light source to the input face of the input lenses of the microlens array. [3] Such microlens matrices thus make it possible to shape the incident light rays in order to form the projection beam of a main beam or that of a dipped beam. In order to comply with current national legislation, dipped beam headlights have a cut-off line which delimits a zone of extinction of the projection beam so as not to dazzle a motor vehicle situated in front and to illuminate only the road situated in front, and on the side of the driving lane. [4] In order to correctly position such a cut-off line, the use of masks is known which, applied to the microlens matrix or associated with said microlens matrix, make it possible to form such a cut-off line. cut-off. Unfortunately, the use of such masks associated with microlens matrices complicates the design of such light modules as well as their manufacturing processes, leading to an increase in their production costs. [5] In order to meet these constraints, the use of microlens matrices that are not associated with such masks is known. In this case, such microlens matrices directly shape the projection beam and its cut-off line, by an optimized dimensioning and geometry of each optical channel and its associated input and output lenses. To this end, the microlens matrix projects images of various dimensions of the associated light source, so as to construct the desired projection beam. [6] Such projected images are partially superimposed on each other in order to form a compact luminous area, i.e. without illumination of the road scene without "holes". A disadvantage of this superposition lies in a strong inhomogeneity of the illumination thus achieved. Indeed, for each area of ​​superposition of two adjacent images of the light source associated with the microlens matrix, a stronger luminous intensity will be observed, while the areas formed by a single image of the associated light source will appear - by contrast - darker. This inhomogeneity of illumination is not satisfactory and is not desired. [7] The object of the present invention is to provide a novel microlens array in order to at least largely address the above problems and to further lead to other advantages. [8] Another object of the invention is to construct a projection beam and its cut-off line without resorting to a mask. [9] Another object of the invention is to reduce the inhomogeneity of the luminous intensity of the projection beam below the cut-off line.

[0010] According to a first aspect of the invention, at least one of the aforementioned objectives is achieved with a microlens matrix for a motor vehicle light module, the microlens matrix being configured to shape light rays generated by a light source in order to generate a projection beam, said microlens matrix comprising: - input lenses comprising an input face configured to receive the light rays, said input faces of the input lenses forming an input face of the microlens array; - output lenses comprising an output face configured to allow light rays to exit the microlens array, said output faces of the output lenses forming an output face of the microlens array, each input lens associated with the facing output lens together forming an optical channel configured to produce an image of the light source.

[0011] According to the invention, a modulated face of the microlens array chosen from the input face and / or the output face of said microlens array has a surface modulation associated with a basic conformation of said modulated face.

[0012] The microlens array forms a two-dimensional array of microlenses. Each microlens thus forms a light channel, when exposed to the light rays emitted by the at least one light source, so as to shape said corresponding light rays in order to create a predetermined light function. In other words, the microlens array is an optical element for shaping a light beam in order to produce a predetermined light function depending on the geometry of the associated microlenses.

[0013] Advantageously, the modulated face of the microlens array has a particular surface geometry in order to produce, for each microlens, a particular optical transformation of the light rays passing through it and, ultimately, of the image of the light source imaged by said microlens. This particular optical transformation aims to blur the peripheral edges of the image of the source imaged by the microlens in question. All or part of the microlenses of the microlens array may have such a modulated surface. In addition, depending on the desired effects, the modulated faces of the microlenses may all be identical or they may be different from each other.

[0014] In the context of the present invention, the surface modulation of the modulated face has a complex geometry that complements the basic conformation of said modulated face. In other words, the surface modulation forms a surface complementary to the basic conformation of the modulated face, said modulated surface being superimposed on the basic conformation of said modulated face. In other words, a given microlens of a matrix of known microlenses comprises an input lens and an output lens that are geometrically defined by a predetermined basic conformation, depending on the desired shaping of the light rays passing through it. According to the invention, the surface modulation is added to and superimposed on this basic conformation, so as to ultimately replace it.

[0015] The surface modulation may be performed on all or part of the input face and / or the output face of the microlens array. In other words, the invention provides that all or part of the microlenses forming the microlens array comprise, either at their input face, or at their output face, or at their input face and their output face, such a surface modulation. Such a surface modulation thus makes it possible to make the image of the light source formed by a given microlens blurred at a peripheral region of said image.

[0016] In the context of the present invention, a part of the formed image is said to be blurred if it has a gradient defined as follows: the gradient corresponds to the maximum value of G(a) = log( I (a + 0.05°)) - log( I (a - 0.05°)) obtained by calculating G(a) for any point of a segment perpendicular to the edge considered of the image, and extending on either side of said edge, where a is the angle, along an axis perpendicular to said edge, of said point of the segment traveled and I the intensity of the light beam for the angle considered. By way of non-limiting example, the edge of the image is considered to be blurred when the gradient is less than 0.30, preferably less than 0.20, in particular less than 0.13. These values ​​ensure an edge of the image that is more blurred than that of a cut-off line of a regulatory code beam.

[0017] Alternatively or additionally, the blurring of a part of the projected image can be demonstrated by comparison between an image of the light source obtained, for a given microlens, without the modulation of surface and that obtained with surface modulation for a given microlens.

[0018] Thus, the microlens array according to the first aspect of the invention solves the technical problem in that it makes it possible to reduce the inhomogeneity of the light intensity of the projection beam shaped by such a microlens array, and in particular under the cut-off line. Such a projection beam is thus obtained by the juxtaposition with overlap of several images of the light source formed by the microlens array, and the progressive decrease in light intensity of which induced by the progressive decrease in the density of the light rays projected at the edges of the image makes it possible to propose better smoothing of the light intensity of the projection beam.This progressive decrease is obtained thanks to the surface modulation associated in a particularly clever manner with an already known basic conformation of all or part of the input face and / or the output face of the lenses forming the microlens matrix according to the invention. Subsequently, the microlens matrix according to the first aspect of the invention makes it possible to construct a projection beam and its cut-off line of high quality and without resorting to a mask.

[0019] The cut-off line has at least one horizontal portion. The cut-off line may further also have at least one inclined portion, said horizontal portion and said at least one inclined portion forming an elbow.

[0020] The microlens matrix advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

[0021] - the surface modulation of the modulated face is characterized by a spatial frequency higher than that of the basic conformation of the modulated face, to which basic conformation the surface modulation is superimposed. In particular, the basic conformation of the modulated face thus forms a regular geometry whose curvature is globally concave or globally convex. In general, the basic conformation does not present abrupt variations in geometry: in the frequency domain, a Fourier transform taken along a proper direction of the face The modulated surface shows a decreasing and monotonous curve, reflecting variations in topography of low spatial frequency, i.e. of long wavelength. On the other hand, the surface modulation of the modulated face forms a more irregular surface, comprising very rapid variations in slopes and changes in concavity or convexity. In the frequency domain, a Fourier transform taken along a natural direction of the modulated face reveals several peaks reflecting the existence of these abrupt variations in topography for a given wavelength. Said peaks correspond to the fundamental frequency and to the harmonics of the modulation. The fundamental frequency of the modulation is advantageously between 2mm- 1 , corresponding to a wavelength of 0.5mm, and 50mm- 1, corresponding to a wavelength of 0.025mm, terminals included. Advantageously, the fundamental frequency of the surface modulation of the modulated face is less than 50mm- 1 . A spatial frequency greater than 50mm- 1 for the fundamental frequency is more similar to mechanical machining of the face of the microlens, such as for example machining, like milling, or polishing of said surface, or of the mold imprint allowing said surface to be obtained.

[0022] - the surface modulation of the modulated face is configured to produce a blur in a first direction at the peripheral region of the image of the light source. Thus, this advantageous configuration makes it possible to reduce the discontinuities in light intensity on the projection beam and in the first direction. The first direction is preferably taken as being horizontal or substantially horizontal, so that the intensity of the projection beam is more homogeneous across the road scene illuminated by the light module intended to be equipped with the microlens array according to the invention, relative to said first direction. To this end, for a given microlens, the surface modulation of the modulated face has surface variations which lead to the generation of such a blur, these surface variations extending close to the edges of said microlens.For example, these surface variations extend parallel or substantially parallel to the edges of the microlens considered. To achieve blurring in the first direction, the edges of the microlens considered along which the. surface variations of the modulated face are defined to extend perpendicularly or substantially perpendicularly to said first direction;

[0023] - similarly, the surface modulation of the modulated face is configured to produce a blur in a second direction at the peripheral region of the image of the light source, the second direction being perpendicular to the first direction. This advantageous configuration makes it possible to reduce the discontinuities in light intensity on the projection beam and in the second direction. The second direction is preferably taken as being vertical or substantially vertical, so that the intensity of the projection beam is more homogeneous across the road scene illuminated by the light module intended to be equipped with the microlens matrix according to the invention, relative to said second direction.To this end, for a given microlens, the surface modulation of the modulated face has surface variations which lead to the generation of such a blur, these surface variations extending close to the edges of said microlens. For example, these surface variations extend parallel or substantially parallel to the edges of the microlens considered. To produce a blur in the second direction, the edges of the microlens considered according to which the surface variations of the modulated face are defined extend perpendicular or substantially perpendicular to said second direction;.

[0024] - the surface modulation of the modulated face is configured to produce a blur in a third direction at the peripheral region of the image of the light source, the third direction being oblique relative to the first direction and the second direction. This advantageous configuration makes it possible to reduce the discontinuities in light intensity on the projection beam in both the first direction and the second direction. The third direction is preferably taken as being oblique, so that the intensity of the projection beam is more homogeneous across the road scene illuminated by the light module intended to be equipped with the microlens matrix according to the invention, relative to said first direction and second direction. To this end, for a given microlens, the surface modulation of the modulated face has surface variations which lead to the generation of such blur. For example, these surface variations extend obliquely relative to the edges of the microlens considered. To achieve blurring in the third direction, the surface variations of the modulated face extend in a direction perpendicular or substantially perpendicular to said third direction. Advantageously, the third direction is parallel to an inclined portion of the cut-off line;

[0025] - the surface variations can take several forms depending on the desired effects and - as previously specified, depending for example on a type of blur and an orientation of the desired blur. In particular, the modulated face surface modulation has concave zones and / or convex zones, so as to stretch the image formed from the light source beyond its initial size by creating a peripheral border whose light intensity decreases progressively, from a central region of the image towards an area outside said image. The presence - and the alternation - of such convex and / or concave parts leads to a more or less significant deviation of the light rays which pass through the surface modulation of the modulated face, thus producing a more homogeneous and more spread-out image of the light source than in the absence of such a modulated face on the microlens matrix;

[0026] - the surface modulation of the modulated face is obtained by the development of a modulation function which determines a thickness of said surface modulation with respect to a reference plane surface. In other words, the shape of the modulated face, i.e. the development of its surface with respect to a plane surface taken as a reference, can be obtained by means of a mathematical function which defines, as a function of predetermined dimensional parameters, a family of surfaces which make it possible to generate the desired blur at the level of the central region. In particular, the surface modulation of the modulated face is obtained by the development of a modulation function which determines a thickness AZ of said surface modulation with respect to the basic conformation of the modulated face. As a non-limiting example, such a modulation function can for example be defined by the following equation: Or : - x is the coordinate of the current point on the modulation profile, xmin and xmax being the value of this coordinate at the level of a first end and a second end of the modulation profile respectively, said profile being characterized here along a proper direction of the surface represented by the set of values ​​of x; - E is the whole part of the following expression placed in parentheses; - A is the amplitude in millimeters of the modulation function AZ - that is, the thickness of the surface modulation added to the basic conformation of the modulated face, said basic conformation producing, in the absence of the surface modulation, the corresponding sharp image of the light source -; - n / 2 is a spatial frequency, in mm -1associated with the number of local extrema present in the modulation function, i.e. the number of local maxima and / or local minima introduced by said modulation function, n being a natural integer. The number of extrema also depends on the overall length of the profile; - p is a positive number impacting the width of the blurred parts of each formed image. In particular, the larger the number p, the larger the unblurred central part of the images of the light source formed by each microlens; and - (p is a dimensional parameter chosen between 0 and 1. The lower the value of (p, the greater the slope of the corresponding modulation function at its local extrema;

[0027] - the modulation function can be chosen to be identical - by its mathematical formulation or by the value of its parameters - for all microlenses in the microlens array, or the modulation function can be chosen specifically - by its mathematical formulation or by the value of its parameters - for each microlens. This configuration advantageous thus allows to shape an optimal projection beam and to process the projected images of the light source in different ways by the microlens matrix;

[0028] - the modulated face comprises the input face of at least a portion of the microlens array. In other words, at least a portion of the input lenses has a modulated face within the meaning of the present invention. In other words, at least a portion of the microlenses of the microlens array have, at their input lens, a modulated face within the meaning of the present invention;

[0029] - the modulated face comprises the output face of at least a portion of the microlens array. In other words, at least a portion of the output lenses has a modulated face within the meaning of the present invention. In other words, at least a portion of the microlenses of the microlens array have, at their output lens, a modulated face within the meaning of the present invention.

[0030] According to a second aspect of the invention, a light module for a motor vehicle is provided, the light module comprising: - at least one light source configured to generate light rays; - a microlens array according to the first aspect of the invention or according to any of its improvements, the input face of the microlens array being optically coupled to the at least one light source.

[0031] In the context of the present invention, the at least one light source is of the type comprising one or more light-emitting diodes. By light-emitting diode is meant any type of light-emitting diodes, such as for example LEDs - English acronym meaning "Light Emitting Diode", OLEDs - English acronym meaning "organic LED", AMOLEDs - English acronym meaning "Active-Matrix-Organic LED", or FOLEDs - English acronym meaning "Flexible OLED". Advantageously, the at least one light source is selectively controlled by a control unit which regulates an electrical supply current for each of the light-emitting diodes in order to control their emission of light rays in order to produce the light function. It is thus possible to control selectively switching the light-emitting diodes to configure them in any configuration between an off configuration and a maximum illumination configuration.

[0032] In the context of the present invention, the at least one light source is optically coupled to the microlens array, so that at least a portion of the light rays generated by the at least one light source is injected into the microlens array. Optionally, the light module comprises optical coupling means located in an optically intermediate position between the at least one light source and the microlens array. By way of non-limiting example, such optical coupling means may comprise, for example, one or more collimators making it possible to orient the light rays generated by the at least one light source towards the entry face of the microlens array.

[0033] Advantageously, the light module comprises a plurality of collimators optically coupling the at least one light source to the input face of the input lenses of the microlens array.

[0034] According to a third aspect of the invention, a lighting device for a motor vehicle is provided, the lighting device comprising a housing housing the lighting module according to the second aspect of the invention.

[0035] Advantageously, the lighting device comprises a support on which the at least one light source of said light module is fixed. The support comprises, for example, at least one electronic card on which the at least one light source of said light module is fixed. Alternatively or additionally, the support may, for example, comprise a radiator.

[0036] In the context of the present invention, the light device is for example of the type of a projector and / or a signal light.

[0037] Various embodiments of the invention are provided, incorporating, according to all of their possible combinations, the various optional features set out herein.

[0038] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of realization given for informational and non-limiting purposes with reference to the schematic drawings annexed on the other hand, on which:

[0039] [Fig.1] illustrates a schematic profile view of a light module comprising a microlens matrix known from the prior art;

[0040] [Fig.2] illustrates a schematic side view of a light module according to the second aspect of the invention and comprising a microlens array according to the first aspect of the invention;

[0041] [Fig.3] illustrates a diagram illustrating the modulation function of the modulated face of the microlens array according to the first aspect of the invention;

[0042] [Fig.4] illustrates a two-dimensional representation of an exemplary embodiment of a part of a non-modulated face, known from the prior art, also representative of the basic conformation of a part of the modulated face according to the invention;

[0043] [Fig.5] illustrates a two-dimensional representation of an exemplary embodiment of a surface of a part of a modulated face, in accordance with the invention;

[0044] [Fig.6] illustrates a representative diagram of a one-dimensional Fourier transform of the unmodulated face and the modulated face illustrated in FIGURES 4 and 5, along the same particular direction of said modulated surface.

[0045] Of course, the features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0046] In particular, all the variants and embodiments described can be combined with each other if there is no technical obstacle to this combination.

[0047] In the figures, elements common to several figures retain the same reference.

[0048] With reference to FIGURE 1, a light module 2 known from the prior art is described. Such a light module 2 comprises at least one light source 22 configured to generate light rays RL, and a matrix 1 of microlenses 10 configured to shape light rays RL generated by the at least one light source 22 in order to generate a projection beam FP, said matrix 1 of microlenses 10 being optically coupled to the at least one light source 22.

[0049] Such a matrix 1 of known microlenses 10 generally comprises:

[0050] - input lenses 101 forming an input face 104 of the matrix 1 of microlenses 10. In particular, the input lenses 101 comprise the input face 104 configured to receive the light rays RL;

[0051] - output lenses 102 forming an output face 105 of the matrix 1 of microlenses 10. In particular, the output lenses 102 comprise the output face 105 configured to allow the light rays RL to exit from the matrix 1 of microlenses 10, said output face 105 of the output lenses 102 forming an output face of the matrix 1 of microlenses 10, each input lens 101 associated with the output lens 102 located opposite together forming an optical channel 103 configured to produce an image IM of the light source 22.

[0052] More particularly, the input lenses 101 of the matrix 1 of microlenses 10 are coupled to the at least one light source 22 via collimators 21 which make it possible to collimate the light rays RL generated by the at least one light source 22 at the level of the input face 104 of the matrix 1 of microlenses 10.

[0053] The input lenses 101 and the output lenses 102 of each microlens 10 of the matrix 1 all have a particular geometry, hereinafter called basic conformation, which makes it possible to generate a clear IM image of a part of the at least one associated light source 22, said image IM being projected in front of the light module 2 - onto a road scene located in front of the motor vehicle equipped with such a known light module 2. Consequently, it is indeed the composition of all the images IM projected from the at least one light source 22 by all the microlenses 10 which makes it possible to produce a light beam 3 across the road scene and illuminating said road scene.

[0054] Obviously, the regulatory constraints regarding lighting of the road scene impose precise characteristics in terms of shape, width and light intensity of such a light beam 3 illuminating the road scene. However, the light beam 3 shaped by the known microlens matrices 10 equipping the known light modules 1 exhibit large inhomogeneities in light intensity. Indeed, as visible in the diagram on the right in FIGURE 1, the light beam 3 produced by the known light modules 1 shows a juxtaposition of light cells of decreasing intensity, framed by light or dark borders, depending on the case.

[0055] These light cells are formed by each of the IM images of the at least one light source 22 projected by the matrix 1 of microlenses 10 - and precisely by each of said microlenses 10 - projected in front of the known light modules 1. Due to the conformation of the known microlens matrices 10, the light cells resulting from the IM image of the at least one light source 22s overlap each other, and this superposition of said IM images leads to local increases in light intensity when two or more IM images are locally superimposed on each other or, conversely, to darker areas when a single IM image of the light source 22 is projected into the light cell in question.

[0056] This variation in light density is not sought because it leads - if not to non-conformities - to the formation of a projection beam FP that is not optimal for use in the automotive field. In particular, such known microlens matrices 10 lead to projecting a beam 3 involving numerous inhomogeneities in illumination and light intensity, in turn leading to great driver fatigue.

[0057] It is clear that the known 10 microlens arrays and 1 light modules fail to meet these two objectives, as illustrated in FIGURE 1.

[0058] In order to solve this technical problem, the invention according to its first aspect provides for modifying the conformation of the known microlens matrices 10. The objective sought here is to make the projection beam FP shaped by the matrix 1 of microlenses 10 according to the invention both more homogeneous without sacrificing the good quality of the cut-off line. Also, such a matrix 1 of microlenses 10 according to the invention now comprises: - input lenses 101 comprising an input face 104 configured to receive the light rays RL, said input face 104 forming an input face of the matrix 1 of microlenses 10; - output lenses 102 comprising an output face 105 configured to allow the light rays RL to exit from the matrix 1 of microlenses 10, said output face 105 of the output lenses 102 forming an output face of the matrix 1 of microlenses 10, each input lens 101 associated with the output lens 102 located opposite together forming an optical channel 103 configured to produce an image IM of the light source 22; According to the invention, a modulated face 11 of the matrix 1 of microlenses 10 has a surface modulation associated with the basic conformation of said modulated face 11.

[0059] The modulated face 11 is chosen from the input face 104 and / or the output face 105 of all or part of the microlenses 10 of the matrix 1 of microlenses 10. The surface modulation of the modulated face 11 thus makes it possible to make the image IM of the light source 22 formed by a given microlens 10 blurred at a peripheral region of said image IM. In other words, the image IM formed by a microlens 10 of the matrix 1 of microlenses 10 is stretched in at least one direction in order to blur at least part of the peripheral edges of the image IM. This stretching is made possible by the surface modulation of the modulated face 11 which is superimposed on the basic conformation of said modulated face 11. The basic conformation produces a sharp IM image of the light source 22, while the surface modulation produces a blurred IM image or IM image portion that combines with the sharp IM image formed by the basic conformation.

[0060] Thus, the anamorphic deformation of the IM image of the at least one light source 22 projected by all or part of the input lenses 101 and / or the output lenses 102 of the modified microlenses 10 of the matrix 1 of microlenses 10 and forming the modulated face 11 makes it possible to modulate the light density at the level of the light beam 3. In other words, the modulated face 11 makes it possible, by blurring certain parts of the IM image, to create a progressive decrease in the light intensity of said IM image, preferentially at its peripheral edges. This progressive decrease, not known on the matrices 1 of known microlenses 10, then makes it possible to juxtapose several IM images at their blurred edges in order to create a more homogeneous light beam 3, in comparison to those produced by the matrices 1 of microlenses 10 known previously.

[0061] As visible on the light beam 3 represented on the right part of FIGURE 2, the light cells formed by the superposition of the images IM of the at least one light source 22 together form - henceforth - a more homogeneous surface on the lower part of the projection beam FP.

[0062] Indeed, the modulated face 11 of the microlens matrix 10 now has a particular surface geometry different from that found on known microlens matrices 10, making it possible to deform the image IM of the at least one light source 22 in a manner more favorable to obtaining a more homogeneous light beam 3 and a progressive decrease in the light intensity of the image IM at a portion of its peripheral edges, or even all of its peripheral edges.

[0063] Of course, in the context of the present invention, the exact geometry of the surface modulation of the modulated face 11 may vary depending on a chosen modulation function. Thus, the invention is of course not limited solely to blurring the peripheral edges of the IM image, and a very different distribution of sharp areas and blurred areas may be observed. inside an image projected by the matrix 1 of microlenses 10 according to the invention.

[0064] Generally speaking, the association of the modulated face 11 with a given microlens 10 leads to the geometry of the microlens 10 being more complex: to its predetermined and known basic conformation, the modulated surface 11 is now superimposed, which itself has a complex geometry. Generally speaking, however, the modulation function can be qualified by a spatial frequency higher than that of the basic conformation: the basic conformation of the modulated face 11 defines its shaping such that it allows a sharp IM image of the light source 22 to be projected to infinity; while the modulated surface has a geometry which allows the light rays associated with the peripheral edges of the IM image to be diverged in order to blur said peripheral edges. This blurred IM image is formed by the surface modulation of the modulated face 11 which transforms the sharp IM image formed by the basic conformation of the modulated face 11.We can thus define, for example, the surface modulation of the modulated face 11 as a variation in thickness relative to the basic conformation of said modulated face 11. This variation in thickness follows a complex profile according to the surface modulation of the modulated face 11 and the desired effects in terms of blurring the peripheral edges of the projected IM image.

[0065] For example, for a given microlens 10, the modulated face 11 may have one or more local extrema - that is to say one or more bulges and / or one or more depressions - which induce the presence of convex part(s) and / or concave part(s) at the level of the modulated face 11. The presence - and the alternation - of such convex parts and such concave parts leads to a more or less significant deviation of the light rays RL which pass through the modulated face 11, thus producing an image IM of the light source 22 which is more homogeneous and more deformed than in the absence of such a modulated face 11 on the matrix 1 of microlenses 10. In other words, the presence - and the alternation - of such convex parts and such concave parts forming the surface modulation of the modulated face leads to a stretching of certain parts of the image IM, and in particular all or part of its peripheral edges, so as to produce a more gradual variation in its luminous intensity at the level of said peripheral edges addressed by the surface modulation.

[0066] According to the invention, the blur produced by the surface modulation of the modulated face 11 can be oriented in a first direction X and / or in a second direction and / or in a third direction. When the geometry of the surface modulation of the modulated face 11 makes it possible to produce a blur in the first direction X, then the light beam 3 has a lesser discontinuity of light intensity along the light cells forming the projection beam FP and in the first direction X. The first direction X is preferably taken as being horizontal or substantially horizontal, so that the intensity of the projection beam FP is more homogeneous across the road scene illuminated by the light module 2 equipped with the matrix 1 of microlenses 10 according to the invention.Alternatively or additionally, when the geometry of the surface modulation of the modulated face 11 makes it possible to produce a blur in the second direction, then the light beam 3 has a lesser discontinuity of light intensity along the light cells forming the projection beam FP and in the second direction. The second direction is preferably taken as being vertical or substantially vertical, so that the intensity of the projection beam FP is more homogeneous in a direction perpendicular or substantially perpendicular to the cut-off line, for such a light module 2 equipped with the matrix 1 of microlenses 10 according to the invention.Alternatively or additionally, when the geometry of the surface modulation of the modulated face 11 makes it possible to produce a blur in the third direction, then the light beam 3 has a lesser discontinuity of light intensity along the light cells forming the projection beam FP and in both the first direction and the second direction. The third direction is preferably taken as being oblique, so that the intensity of the projection beam FP is more homogeneous in both the first direction and the second direction, for such a light module 2 equipped with the matrix 1 of microlenses 10 according to the invention. Advantageously, the third direction is parallel to an inclined part of the cut-off line.

[0067] The choice of creating such a blur on the IM image projected in the first direction and / or the second direction depends in particular on the position of the IM image in the projected light beam 3: - if the image IM projected by a microlens 10 is located close to or even touches a horizontal part of the cut-off line of the light beam 3, then the blur generated by the surface modulation of the corresponding modulated face 11 is exclusively oriented along the horizontal direction of the image IM; - if the IM image projected by a microlens 10 is located at a distance from the cut-off line of the light beam 3, relative to the vertical axis, then the blur generated by the surface modulation of the corresponding modulated face 11 is oriented in the horizontal direction of the IM image and / or in the vertical direction of the IM image; - if the IM image projected by a microlens 10 is located near or even touches an inclined part of the cut-off line of the light beam 3, then the corresponding microlens does not have a modulated face so that the projected IM image does not have either vertical blur or horizontal blur. Alternatively, the corresponding microlens has a modulated face and the blur generated by the surface modulation of the corresponding modulated face 11 is exclusively oriented in an oblique direction relative to the horizontal direction and the vertical direction of the IM image, said oblique direction being parallel to said inclined part of the cut-off line. This configuration makes it possible to improve the homogeneity of the beam while maintaining good sharpness of the inclined part of the cut-off line.

[0068] According to a particularly interesting embodiment of the invention, the surface modulation of the modulated face 11 is obtained by developing a modulation function which determines a thickness of said surface modulation relative to the basic conformation of the modulated face 11. Such a modulation function is illustrated in FIGURE 3 which represents a normalized amplitude AZ / Z of the modulated face 11 taken along the first direction X and / or the second direction. The modulation function thus makes it possible to determine a thickness AZ of the surface of the modulated face 11 relative to the basic conformation of the modulated face 11 taken as reference.

[0069] An example of a modulation function is defined by the following equation: - x is the coordinate of the current point on the modulation profile, xmin and xmax being the value of this coordinate at the level of a first end and a second end of the modulation profile respectively, said profile being characterized here along a proper direction of the surface represented by the set of values ​​of x; - E is the whole part of the following expression placed in parentheses; - A is the amplitude in millimeters of the modulation function AZ - that is, the thickness of the surface modulation added to the basic conformation of the modulated face, said basic conformation producing, in the absence of the surface modulation, the corresponding sharp image of the light source; - n / 2 is a spatial frequency, in mm -1 ; - p is a positive number impacting the width of the blurred parts of each IM image formed. In particular, the larger the number p, the larger the unblurred central part of the IM images of the light source 22 formed by each microlens 10; and - (p is a dimensional parameter chosen between 0 and 1. The lower the value of (p, the greater the slope of the corresponding modulation function at its local extrema.

[0070] We can thus see on the graph of FIGURE 3 that the modulation function characterizing the modulated face 11 of the matrix 1 of microlenses 10 according to the invention comprises: - first zones Z1 corresponding to parts of the horizontal or substantially horizontal modulation function. Such first zones Z1 correspond to parts of non-deflection or lesser deviation of the incident light rays RL, so that said light rays RL propagate through the modulated face 11 without being diverged. The first zones Z1 thus make it possible to propose a neutral transformation for the rays luminous RL in the formation of the image IM of the at least one light source 22; - second zones Z2 corresponding to parts of the modulation function having a maximum slope. Such second zones Z2 correspond to parts of maximum deviation or significant deviation of the incident light rays RL, so that said light rays RL propagate through the modulated face 11 converge or diverge towards a lateral zone of the light cell. The second zones Z2 thus make it possible to increase the width or the height of the light cell in order to allow the partial superposition of several adjacent images IM of the at least one light source 22 without an overcurrent zone; - third zones Z3 corresponding to local extremums of the modulation function, i.e. zones of reversal of a tangent to said modulation function. Such third zones Z3 correspond to parts of maximum divergence or significant divergence of the incident light rays RL, so that said light rays RL propagating through the modulated face 11 diverge in several given directions around the local extremum. The third zones Z3 thus make it possible to avoid an accumulation of images IM at the blurred peripheral edges created by the surface modulation, which would have the consequence of causing an overintensity to appear which would be unfavorable for obtaining a homogeneous overall beam. For this purpose, the half-tangents taken at the level of each third zone Z3 advantageously have high slopes.

[0071] Furthermore, it is observed that, in the embodiment illustrated in FIGURE 3, the modulation function has a spatial frequency of order L / 3 where L is the dimension of the image IM according to which the blur is generated, i.e. along the abscissa profile “x”, since three identical patterns M are reproduced periodically between the two opposite edges of the modulated face 11, taken according to the first and / or the second direction X,Y.

[0072] Finally, according to a first embodiment of the invention, all the microlenses 10 of the matrix 1 of microlenses 10 comprise a modulated face 11 or, according to a second embodiment as illustrated schematically in FIGURE 2, only a part of the microlenses 10 comprise a modulated face 11. Furthermore, the modulated faces 11 of all the microlenses 10 comprising such modulated faces 11 may all be identical or they may be different, depending on the desired effects and the contribution of a given microlens 10 in the construction of the projection beam FP and its cut-off line for example.

[0073] FIGURES 4, 5 and 6 allow us to qualify the modulated face 11 in a more qualitative and quantitative manner. In particular: - FIGURE 4 represents a part of an unmodulated face 11 B, known from the prior art, also corresponding to a part of the basic conformation of the face of the modulated face 11 according to the invention. The x, y and z axes of the reference frame are all represented in millimeters; - FIGURE 5 represents a part of a modulated face 11, in accordance with the invention, obtained by adding a modulation to the non-modulated face 11 B of FIGURE 4. The x, y and z axes of the reference frame are all represented in millimeters; It should be noted that in FIGURES 4 and 5, the scale of the z axis is very dilated compared to that of the x and y axes. This allows the modulations of the modulated surface 11 to be clearly seen in FIGURE 5. - FIGURE 6 illustrates the Fourier transform of the surfaces illustrated in FIGURES 4 and 5 and in the same particular direction corresponding to a rectilinear profile taken along each surface, more precisely along the segment parallel to the x axis and positioned at y=0. The abscissa axis represents the spatial frequency, expressed in mm -1. The y-axis corresponds to the coefficient assigned to the component of a given frequency, in Fourier space. Thus, along the profile from which the Fourier transform is calculated, the shape of the modulated face 11 corresponds to the integral sum of the sinusoids of given frequency weighted by the corresponding coefficient. It should also be noted that, in FIGURE 6, the values ​​of the Fourier transform close to the origin of the x-axis have been truncated. In fact, the coefficients there are greater than 1, which is the maximum value represented to ensure the readability of the curves.

[0074] Referring to FIGURE 4, it is observed that the unmodulated face 11 B, corresponding to the basic conformation of the modulated face 11 , forms a regular geometry. The curvature of the basic conformation is globally concave or globally convex. More specifically, the basic conformation of the modulated face is exclusively concave or exclusively convex. Generally speaking, the basic conformation does not present abrupt variations in geometry. This regular topography is qualified in the frequency domain by the Fourier transform illustrated in FIGURE 6 by the TFB curve in dotted lines. It is observed that the Fourier transform of the basic conformation is a decreasing and monotonic curve, as the spatial frequencies increase. In other words, the geometry of the basic conformation of the modulated face 11 is a surface dominated by long wavelengths, i.e. at low spatial frequencies, thus reflecting the smooth and progressive evolution of the profile of the geometry of the basic conformation.

[0075] On the other hand, with reference to FIGURE 5, it is observed that the modulated face 11 forms a more irregular surface showing abrupt variations in topography, including very rapid variations in slopes and changes in concavity or convexity of the surface modulation. This very irregular topography is qualified in the frequency domain by the Fourier transform illustrated in FIGURE 6 by the TFM curve in solid line. It is observed that the Fourier transform of the modulated face 11 is a globally decreasing curve but including several high amplitude peaks superimposed on the decreasing trend of the curve. The globally decreasing characteristic of the surface modulation is linked to its superposition on the basic conformation, the surface modulation taking up the long wavelength structural characteristics of the basic conformation.The peaks that rise above the generally decreasing curve correspond to the fundamental frequency and to odd order harmonics, i.e. harmonics whose frequency is an odd multiple of the fundamental frequency, in the example illustrated here. Of course, this example is not limiting, and many harmonic distributions could be compatible with the modulated face 11 of the invention, in particular even order harmonics, i.e. harmonics whose frequency is an even multiple of the fundamental frequency, or both even and odd order harmonics.

[0076] Each harmonic qualifies a spatial frequency representative of the modulated face 11: the first peak F corresponds to the fundamental frequency of the modulated face 11, that is to say to the spatial frequency most represented on the modulation of the profile of the modulated face 11 along which the Fourier transform is calculated. This first peak here has a maximum located at 5mm- 1 , corresponding to a wavelength of the order of 0.2mm. Advantageously, the fundamental frequency is between 2mm- 1 , corresponding to a wavelength of 0.5mm, and 50mm- 1 , corresponding to a wavelength of 0.025mm, terminals included.

[0077] Advantageously, the fundamental frequency of the surface modulation of the modulated face is less than 50mm- 1 . A peak in the Fourier transform located beyond 50mm- 1for the fundamental frequency is not representative of the invention and the surface modulation. On the contrary, such a peak would be representative of mechanical machining of the face of the microlens, such as for example polishing or milling of said surface, or of the mold imprint allowing said surface to be obtained. On the other hand, harmonic frequency peaks located beyond 50mm- 1 are compatible with the invention.

[0078] In the example of the modulated face 11 whose Fourier transform is illustrated in FIGURE 6, the visible harmonics are those of order 3 corresponding to the peak H3 with a maximum located at 15mm- 1 and of order 5 corresponding to the H5 peak with a maximum located at 25mm- 1 .

[0079] The Fourier transforms that would be obtained for these surfaces along segments parallel to the x-axis and positioned at y-values ​​other than 0 would be similar to those described previously in connection with FIGURE 6. On the other hand, the Fourier transforms that would be obtained for segments parallel to the y-axis would be similar to that described previously for the basic conformation. Indeed, the modulation of the modulated surface 11 of this example is only present along the x-direction. However, it is possible to have a modulation along the y-direction. It is also possible to have both a modulation along the x-direction and a modulation along the y-direction.

[0080] In summary, the invention relates to a matrix 1 of microlenses 10 for a light module 2 of a motor vehicle, the matrix 1 of microlenses 10 being configured to shape light rays RL generated by a light source 22 in order to generate a projection beam FP, said matrix 1 of microlenses 10 comprising input lenses 101 forming an input face 104 of the matrix 1 of microlenses 10, output lenses 102 forming an output face 105 of the matrix 1 of microlenses 10, the input lenses 101 and the output lenses 102 forming two by two an optical channel 103 configured to project an image IM of the light source 22. A modulated face 11 of the matrix 1 of microlenses 10 has a modulated surface 11 which is superimposed on a basic conformation of said modulated face, so as to create a progressive decrease in light intensity at the peripheral edges of the IM image thus projected.

[0081] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations to the extent that they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above can be combined with each other.

Claims

Claims

1. Matrix (1) of microlenses (10) for a light module (2) of a motor vehicle, the matrix (1) of microlenses (10) being configured to shape light rays (RL) generated by a light source (22) in order to generate a projection beam (FP), said matrix (1) of microlenses (10) comprising: - input lenses (101) comprising an input face (104) configured to receive the light rays (RL), said input faces (104) of the input lenses (101) forming an input face of the matrix (1) of microlenses (10); - output lenses (102) comprising an output face (105) configured to allow the light rays (RL) to exit from the matrix (1) of microlenses (10), said output faces (105) of the output lenses (102) forming an output face of the matrix (1) of microlenses (10), each input lens (101) associated with the output lens (102) located opposite together forming an optical channel (103) configured to produce an image (IM) of the light source (22); characterized in that a modulated face (11) of the matrix (1) of microlenses (10) chosen from the input face (104) and / or the output face (105) of said matrix (1) of microlenses (10) has a surface modulation associated with a basic conformation of said modulated face (11).

2. Array (1) of microlenses (10) according to the preceding claim, in which the surface modulation of the modulated face (11) is configured to produce a blur in a first direction (X) at the peripheral region of the image (IM) of the light source (22).

3. Array (1) of microlenses (10) according to the preceding claim, wherein the surface modulation of the modulated face (11) is configured to produce a blur in a second direction at the peripheral region of the image (IM) of the light source (22), the second direction being perpendicular to the first direction (X).

4. An array (1) of microlenses (10) according to any preceding claim, wherein the surface modulation of modulated face (11) has concave zones and / or convex zones, so as to stretch the image (IM) formed from the light source (22) beyond its initial size by creating a peripheral border whose light intensity decreases progressively, from a central region of the image towards a zone outside said image (IM).

5. An array (1) of microlenses (10) according to any preceding claim, wherein the modulated face (11) comprises the output face (105) of at least a portion of the array (1) of microlenses (10).

6. An array (1) of microlenses (10) according to any preceding claim, wherein the modulated face (11) comprises the input face (104) of at least a portion of the array (1) of microlenses (10).

7. Light module (2) for a motor vehicle, the light module (2) comprising: - at least one light source (22) configured to generate light rays (RL); - an array (1) of microlenses (10) according to any one of the preceding claims, the input face (104) of the array (1) of microlenses (10) being optically coupled to the at least one light source (22).

8. A lighting device for a motor vehicle, the lighting device comprising a housing housing the lighting module (2) according to the preceding claim.

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