Microlens array and light emitting module for a motor vehicle

Abstract

The present invention relates to an array (1) of microlenses (10) for a light-emitting module (2) of a motor vehicle, the array (1) of microlenses (10) being configured to shape light (RL) generated by a light source (22) to generate a projected beam (FP). The array (1) of microlenses (10) includes: incident lenses (101) forming an incident surface (104) of the array (10); and exit lenses (102) forming an exit surface (105) of the array (10). The incident lenses (101) and the exit lenses (102) are paired to form an optical channel (103) configured to project an image (IM) of the light source (22). The modulation surface (11) of the array (10) of microlenses (10) has a modulation surface superimposed on the basic configuration of the modulation surface (11) to produce a gradual decrease in luminous intensity at the peripheral edges of the thus projected image (IM).

Description

[0001] The technical background of this invention is the technical background of light-emitting illumination devices for motor vehicles. More specifically, this invention relates to a microlens array and a light-emitting module for motor vehicles including such a microlens array.

[0002] In the prior art, it is known to use light-emitting modules in light-emitting devices for motor vehicles, which enable the formation of a headlight beam that serves as either high beam or low beam to illuminate the road scene ahead of the motor vehicle. Such known light-emitting modules include: - At least one light source, which is configured to produce light; - A microlens array comprising an incident lens forming an incident surface of the microlens array and an exit lens forming an exit surface of the microlens array, each incident lens being coupled to an opposite exit lens via an optical channel, the microlens array being configured to shape light generated by the at least one light source in order to generate a projected beam. - Multiple collimators that optically couple at least one light source to the incident surface of the incident lens of the microlens array.

[0003] Therefore, this microlens array allows for the shaping of incident light rays to form either a high beam or a low beam. To comply with current national regulations, the low beam includes a cutoff line that defines a dark area of ​​the projected beam to prevent glare to oncoming vehicles and to illuminate only the road ahead and one side of the lane in which the vehicle is traveling.

[0004] To accurately position this cutoff line, it is known to use a mask, which, when applied to or associated with a microlens array, allows the formation of this cutoff line. Unfortunately, combining such a mask with a microlens array complicates the design and manufacturing process of this light-emitting module, leading to increased production costs.

[0005] To overcome these constraints, it is known to use a microlens array not associated with such a mask. In this case, the dimensions of each optical channel and its associated incident and exit lenses are determined and their geometry optimized so that the microlens array directly forms the projected beam and its cutoff line. To this end, the microlens array projects images of different sizes of the associated light source in order to construct the desired projected beam.

[0006] The projected images are partially superimposed on each other to form a compact luminous field—that is, a luminous field that illuminates the road scene without “holes.” One drawback of this superposition is the resulting highly uneven illumination. Specifically, for each superimposed region of two adjacent images of a light source associated with the microlens array, a higher luminous intensity will be observed, while the region formed by the single image of the associated light source will appear darker in comparison. This unevenness of illumination is unsatisfactory and undesirable.

[0007] One object of the present invention is to propose a new microlens array that addresses at least most of the aforementioned problems and provides other advantages.

[0008] Another objective of this invention is to construct the projected beam and its cutoff line without the need for the use of a mask.

[0009] Another objective of this invention is to reduce the non-uniformity of the luminous intensity of the projected beam below the cutoff line.

[0010] According to a first aspect of the invention, at least one of the aforementioned objectives is achieved by an array of microlenses for a light-emitting module of a motor vehicle, the array of microlenses being configured to shape light generated by a light source to produce a projected beam, the array of microlenses comprising: - Incident lenses, which include incident surfaces configured to receive light, the incident surfaces of the incident lenses forming the incident surfaces of an array of microlenses; - Exit lenses, which include an exit surface configured to allow light to exit from an array of microlenses, the exit surfaces of the exit lenses forming the exit surfaces of the array of microlenses, each incident lens being associated with an opposite exit lens, together forming an optical channel configured to produce an image of the light source.

[0011] According to the present invention, the modulation surface of the array of microlenses, selected from the incident and / or exit surfaces of the array of microlenses, has surface modulation associated with the basic configuration of the modulation surface.

[0012] An array of microlenses forms a two-dimensional microlens array. Therefore, when exposed to light emitted by the at least one light source, each microlens forms a light-emitting channel to shape the corresponding light, thereby producing a predetermined light-emitting function. In other words, a microlens array is an optical element used to form a light beam to perform a predetermined light-emitting function according to the geometry of the associated microlenses.

[0013] Advantageously, the modulation surface of the microlens array has a specific surface geometry to produce a specific optical transformation for the light passing through each microlens, and ultimately a specific optical transformation for the image of the light source imaged by the microlens. This specific optical transformation is intended to blur the peripheral edges of the image of the source imaged by the microlens in question. All or some of the microlenses in the microlens array may have such a modulation surface. Furthermore, depending on the desired effect, the modulation surfaces of the microlenses may all be identical or they may differ from one another.

[0014] In the context of this invention, the surface modulation of the modulation surface has a complex geometry complementary to the basic configuration of the modulation surface. In other words, the surface modulation forms a surface complementary to the basic configuration of the modulation surface, which is superimposed on the basic configuration of the modulation surface. Furthermore, a given microlens in a known array of microlenses comprises an incident lens and an exit lens, the geometry of which is defined by a predetermined basic configuration, specifically depending on how the light passing through it is desired to be shaped. According to the invention, surface modulation is added to and superimposed on this basic configuration in order to ultimately replace it.

[0015] All or some of the surfaces of the incident and / or exit surfaces of a microlens array can be modulated. In other words, the present invention provides that all or some of the microlenses forming a microlens array include such surface modulation on their incident surface, or on their exit surface, or on both their incident and exit surfaces. This surface modulation thus makes it possible to blur the image of the light source formed by a given microlens in the peripheral region of the image.

[0016] In the context of this invention, a portion of the formed image is referred to as blurred if it has a gradient defined as follows: the gradient corresponds to the maximum value of G(α) = log(I(α + 0.05°)) - log(I(α - 0.05°)), which is obtained by calculating G(α) for any point in a segment perpendicular to and extending on both sides of the relevant edge of the image, where α is the angle of the point in the probed segment along an axis perpendicular to the edge, and I is the intensity of the light beam at the angle in question. As a non-limiting example, the edges of the image are considered blurred when the gradient is less than 0.30, preferably less than 0.20, and especially less than 0.13. These values ​​ensure that the edges of the image are more blurred than the regulated near-light cutoff line.

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

[0018] Therefore, the microlens array according to the first aspect of the invention solves the technical problem because it makes it possible to reduce the non-uniformity of the luminous intensity of the projected beam (particularly below the cutoff line) formed by such a microlens array. Thus, this projected beam is obtained by overlapping and juxtaposing multiple images of a light source formed by the array of microlenses, and the gradual decrease in the luminous intensity of the projected beam (caused by the gradual decrease in the density of light projected at the edges of the images) allows for better smoothing of the luminous intensity of the projected beam. This gradual decrease is achieved by means of surface modulation associated in a particularly ingenious manner with all or some of the known basic configurations of the incident and / or exit surfaces of the lenses forming the microlens array according to the invention. Subsequently, the microlens array according to the first aspect of the invention makes it possible to construct a high-quality projected beam and its cutoff line without the need for a mask.

[0019] The cutoff line has at least one horizontal portion. The cutoff line may also include at least one inclined portion, the horizontal portion and the at least one inclined portion forming a kink.

[0020] The microlens array advantageously includes at least one of the following improvements, and the technical features forming these improvements can be implemented individually or in combination: - Surface modulation of the modulation surface is characterized by a spatial frequency higher than that of the basic configuration of the modulation surface, with the surface modulation superimposed on the basic configuration. Specifically, the basic configuration of the modulation surface thus forms a regular geometry whose curvature is generally concave or generally convex. Typically, the basic configuration does not exhibit any abrupt changes in geometry: in the frequency domain, the Fourier transform calculated along the characteristic direction of the modulation surface returns a decreasing and monotonic curve, reflecting changes in morphology at low spatial frequencies (i.e., long wavelengths). In contrast, surface modulation of the modulation surface forms a more irregular surface, including very rapid changes in slope and variations in concavity or convexity. In the frequency domain, the Fourier transform calculated along the characteristic direction of the modulation surface has multiple peaks, reflecting these abrupt changes in morphology for a given wavelength. These peaks correspond to the fundamental frequency and harmonics of the modulation. The fundamental frequency of the modulation is advantageously at 2 mm. -1 (Corresponding to a wavelength of 0.5 mm) and 50 mm -1 (Corresponding to a wavelength of 0.025 mm) , including the limiting values. Advantageously, the fundamental frequency of surface modulation of the modulation surface is less than 50 mm. -1 For the fundamental frequency, greater than 50 mm -1 The spatial frequency will be more like the surface of a microlens, such as a surface obtained by machining (e.g., milling) or polishing the surface, or by an imprint of a mold that allows the surface to be obtained.

[0021] - The surface modulation of the modulation surface is configured to produce blurring in a first direction in the peripheral region of the image of the light source. Therefore, this advantageous configuration allows for reduction of discontinuities in the luminous intensity of the projected beam in the first direction. The first direction is preferably horizontal or substantially horizontal, such that the intensity of the projected beam is more uniform relative to the first direction in a road scene illuminated by a light-emitting module designed to be equipped with a microlens array according to the invention. For this purpose, for a given microlens, the surface modulation of the modulation surface exhibits surface variations that result in this blurring, these surface variations being close to the edge of the microlens. For example, these surface variations extend parallel or substantially parallel to the edge of the microlens in question. To produce blurring in the first direction, the edge of the microlens in question extends perpendicular or substantially perpendicular to the first direction, and the surface variations of the modulation surface define the edge along the edge; Similarly, the surface modulation of the modulation surface is configured to produce blurring in a second direction perpendicular to the first direction in the peripheral region of the image of the light source. This advantageous configuration allows for reduction of discontinuities in the luminous intensity of the projected beam in the second direction. The second direction is preferably vertical or substantially vertical, such that the intensity of the projected beam is more uniform relative to the second direction in a road scene illuminated by a light-emitting module designed to be equipped with a microlens array according to the invention. To this end, for a given microlens, the surface modulation of the modulation surface exhibits surface variations that result in this blurring, these surface variations being close to the edge of the microlens. For example, these surface variations extend parallel or substantially parallel to the edge of the microlens in question. In order to produce blurring in the second direction, the surface variations of the modulation surface define the edge perpendicular or substantially perpendicular to the second direction. - The surface modulation of the modulation surface is configured to produce blurring in a third direction in the peripheral region of the image of the light source, the third direction being inclined relative to the first and second directions. This advantageous configuration allows for reduction of discontinuities in the luminous intensity of the projected beam in both the first and second directions. The third direction is preferably inclined, such that the intensity of the projected beam is more uniform in a road scene illuminated by a light-emitting module intended to be equipped with a microlens array according to the invention, relative to the first and second directions. For this purpose, for a given microlens, the surface modulation of the modulation surface exhibits surface variations that cause this blurring. For example, these surface variations extend obliquely relative to the edge of the microlens in question. In order to produce blurring in the third direction, the surface variations of the modulation surface extend in a direction perpendicular to or substantially perpendicular to the third direction. Advantageously, the inclined portion of the third direction is parallel to the cutoff line; - Surface variations can take many forms, depending on the desired effect and, as mentioned above, on, for example, the type of blur and the orientation of the desired blur. Specifically, the surface modulation of the modulation surface has concave and / or convex regions to stretch the image formed by the light source beyond its initial size by creating peripheral boundaries, the luminous intensity of which gradually decreases from the central region of the image to the region outside the image. The presence (and alternation) of these convex and / or concave portions causes a relatively significant deviation in the light rays passing through the surface modulation of the modulation surface, thereby producing an image of the light source that is more uniform and more diffuse than in the absence of such a modulation surface on the microlens array; - The surface modulation of the modulation surface is obtained by deriving a modulation function that defines the thickness of the surface modulation relative to a planar reference surface. In other words, the shape of the modulation surface (i.e., the derivation of its surface relative to a planar surface as a reference) can be obtained by a mathematical function that defines a family of surfaces according to predetermined dimensional parameters, the family of surfaces allowing the generation of ambiguity sought in the central region. Specifically, the surface modulation of the modulation surface is obtained by deriving a modulation function that defines the thickness ΔZ of the surface modulation relative to the basic configuration of the modulation surface. As a non-limiting example, such a modulation function can be defined, for example, by the following equation: in: - x is the coordinate of the current point on the modulation profile, and xmin and xmax are the values ​​of this coordinate at the first and second ends of the modulation profile, respectively. The profile is characterized in the characteristic direction of the surface represented by the set of all values ​​of x. - E is the integer part of the following expression within the parentheses; - A is the amplitude of the modulation function ΔZ in millimeters, which is the thickness of the surface modulation added to the basic configuration of the modulation surface, which produces a clear image of the light source in the absence of surface modulation. - n / 2 is the spatial frequency (in mm) -1 The number of extrema (in units) is related to the number of local extrema present in the modulation function (i.e., the number of local maxima and / or local minima introduced by the modulation function), where n is a natural number. The number of extrema also depends on the total length of the profile; - p is a positive number that affects the width of the blurred portion of each image formed. Specifically, the larger the number p, the larger the unblurred center portion of the image of the light source formed by each microlens; and - φ is a size parameter chosen between 0 and 1. The smaller the value of φ, the greater the slope of the corresponding modulation function at its local extrema; - For all microlenses in the microlens array, the modulation function can be chosen to be the same either through its mathematical formula or through the values ​​of its parameters, or the modulation function can be chosen to be specific to each microlens either through its mathematical formula or through the values ​​of its parameters. This advantageous configuration thus allows for the formation of an optimal projected beam and allows for the different processing of the image of the light source projected by the microlens array; - The modulation surface includes at least a portion of the incident surface of the microlens array. In other words, at least some of the incident lenses have a modulation surface as understood in this invention. Furthermore, at least some of the microlenses in the microlens array have an incident lens with a modulation surface as understood in this invention. - The modulation surface includes the exit surface of at least a portion of the microlens array. In other words, at least some of the exit lenses have a modulation surface as defined in this invention. Furthermore, at least some of the microlenses in the microlens array have an exit lens that has a modulation surface as defined in this invention.

[0022] According to a second aspect of the present invention, a light-emitting module for a motor vehicle is provided, the light-emitting module comprising: - At least one light source, which is configured to produce light; - According to the first aspect of the invention or any improvement thereof, the incident surface of the array of microlenses is optically coupled to the at least one light source.

[0023] In the context of this invention, the at least one light source is of a type comprising one or more light-emitting diodes (LEDs). LED means any type of LED, such as conventional LEDs, organic LEDs (OLEDs), active-matrix organic LEDs (AMOLEDs), or flexible OLEDs (FOLEDs). Advantageously, the at least one light source is selectively driven by a control unit that regulates the supply current to each of the LEDs to control their light emission, thereby producing a light-emitting function. This allows the LEDs to be selectively driven to be configured to any configuration between an off configuration and a maximum illumination configuration.

[0024] In the context of this invention, the at least one light source is optically coupled to the microlens array such that at least some of the light generated by the at least one light source is injected into the microlens array. Optionally, the light-emitting module includes an optical coupling device located optically intermediate between the at least one light source and the microlens array. As a non-limiting example, such an optical coupling device may include, for example, one or more collimators that can direct the light generated by the at least one light source in the direction of incident on the surface of the microlens array.

[0025] Advantageously, the light-emitting module includes a plurality of collimators that optically couple the at least one light source to the incident surface of the incident lens of the microlens array.

[0026] According to a third aspect of the invention, a light-emitting device for a motor vehicle is provided, the light-emitting device comprising a housing that houses a light-emitting module according to a second aspect of the invention.

[0027] Advantageously, the light-emitting device includes a carrier to which at least one light source of the light-emitting module is secured. The carrier may include, for example, at least one circuit board to which at least one light source of the light-emitting module is secured. Alternatively or additionally, the carrier may include, for example, a heat sink.

[0028] In the context of this invention, the light-emitting device is, for example, a headlight and / or a signal light.

[0029] Various embodiments of the invention are provided, which incorporate the various optional features described herein in all possible combinations.

[0030] On the one hand, other features and advantages of the invention will become clearer from the following description, and on the other hand, from the numerous non-limiting examples of embodiments given in an indicative manner with reference to the accompanying illustrative drawings, in which: [ Figure 1 This image shows a schematic outline view of a light-emitting module, including a known prior art microlens array; [ Figure 2 A schematic outline view of a light-emitting module that includes a microlens array according to a second aspect of the invention and a first aspect of the invention is shown. [ Figure 3 The graph shows a modulation function of the modulation surface of a microlens array according to a first aspect of the invention. [ Figure 4 This image shows a two-dimensional representation of an example of a portion of a known prior art unmodulated surface, which also represents a basic configuration of a portion of a modulated surface according to the invention; [ Figure 5 [This image shows a two-dimensional representation of an example of a surface representing a portion of a modulation surface according to the present invention;] [ Figure 6 [This shows the meaning] Figure 4 and Figure 5 The graphs shown are one-dimensional Fourier transform curves of the unmodulated surface and the modulated surface in the same specific direction on the modulated surface.

[0031] Of course, the features, variations, and various embodiments of the present invention can be associated with each other in various combinations, as long as they are compatible or not mutually exclusive. In particular, it is conceivable that variations of the present invention may include only the features selected below and described independently of the other features described, provided that such selection of features is sufficient to provide a technical advantage or to distinguish the present invention from the prior art.

[0032] In particular, if there is nothing from a technical point of view that prevents the combination of all the described variations and all the embodiments, then they can be combined with each other.

[0033] In the accompanying drawings, elements included in more than one drawing are indicated by the same reference numerals in all of them.

[0034] refer to Figure 1 The prior art light-emitting module 2 will now be described. Such a light-emitting module 2 includes: at least one light source 22 configured to generate light RL; and an array 1 of microlenses 10 configured to shape the light RL generated by the at least one light source 22 to generate a projected light beam FP, the array 1 of microlenses 10 being optically coupled to the at least one light source 22.

[0035] Such an array 1 of known microlenses 10 typically includes: - Incident lenses 101, which form the incident surface 104 of the array 1 of microlenses 10. In particular, the incident lens 101 includes the incident surface 104, which is configured to receive light rays RL; - Exit lenses 102, which form the exit surface 105 of the array 1 of microlenses 10. Specifically, the exit lens 102 includes an exit surface 105 configured to allow light rays RL to exit from the array 1 of microlenses 10, the exit surface 105 of the exit lens 102 forming the exit surface of the array 1 of microlenses 10, each incident lens 101 associated with an opposite exit lens 102, together forming an optical channel 103 configured to generate an image IM of the light source 22.

[0036] More specifically, the incident lens 101 of the array 1 of microlenses 10 is coupled to the at least one light source 22 via collimators 21, which allow the light RL generated by the at least one light source 22 to be collimated at the incident surface 104 of the array 1 of microlenses 10.

[0037] Each microlens 10 in array 1 has an incident lens 101 and an exit lens 102 comprising a specific geometry (hereinafter referred to as the basic configuration) that allows for the generation of a clear image IM of a portion of at least one associated light source 22, which is projected in front of the light-emitting module 2, i.e., onto a road scene located in front of a motor vehicle equipped with such a known light-emitting module 2. Therefore, it is the combination of all the images IM of at least one light source 22 projected by all the microlenses 10 that allows the light beam 3 to be generated on and illuminate the road scene.

[0038] Of course, regulatory constraints applicable to road scene lighting require that the beam 3 illuminating the road scene possess precise characteristics in terms of its shape, size, and luminous intensity. However, the beam 3 formed by the known microlens array 10 equipped with the known light-emitting module 1 exhibits significant non-uniformity in luminous intensity. Specifically, as... Figure 1 As shown on the right, the light beam 3 generated by the known light-emitting module 1 causes the light-emitting units to be seen to be juxtaposed with reduced intensity, and the light-emitting units are framed by bright or dark boundaries depending on the specific situation.

[0039] These light-emitting units are formed by each of the images IM of the at least one light source 22, which are projected in front of the known light-emitting module 1 by the array 1 of microlenses 10 (and more precisely by each of the microlenses 10). Due to the configuration of the array of known microlenses 10 (i.e., the microlens array), the light-emitting units generated by the images IM of the at least one light source 22 overlap with each other, and when two or more images IM are locally superimposed on each other, this superposition of the images IM results in a local increase in luminous intensity, or conversely, when a single image IM of the light source 22 is projected onto the light-emitting unit in question, it results in a darker area.

[0040] This variation in luminous density is not desirable because it results in (if not non-compliance) a projection beam FP that is not optimal for use in the automotive field. In particular, this array of microlenses 10 is known to cause the projection of beam 3 to contain many non-uniformities in illumination and luminous intensity, which in turn leads to high driver fatigue.

[0041] It goes without saying, such as Figure 1 The known array of microlenses 10 and the known light-emitting module 1 shown do not satisfy these two objectives.

[0042] To address this technical problem, the present invention, according to its first aspect, provides a modified configuration of a known array of microlenses 10. In fact, the objective sought here is to make the projected beam FP formed by the array 1 of microlenses 10 according to the invention more uniform without sacrificing good quality of the cutoff line. Therefore, such an array 1 of microlenses 10 according to the invention now comprises: - Incident lenses 101, these incident lenses include incident surfaces 104 configured to receive light rays RL, the incident surfaces 104 forming the incident surfaces of the array 1 of microlenses 10; - Exit lenses 102, these exit lenses include exit surfaces 105, which are configured to allow light rays RL to exit from the array 1 of microlenses 10, the exit surfaces 105 of the exit lenses 102 forming the exit surfaces of the array 1 of microlenses 10, each incident lens 101 associated with an opposite exit lens 102, together forming an optical channel 103, which is configured to generate an image IM of the light source 22; according to the invention, the modulation surface 11 of the array 1 of microlenses 10 has surface modulation associated with the basic configuration of the modulation surface 11.

[0043] The modulation surface 11 is selected from the incident surface 104 and / or exit surface 105 of all or some of the microlenses 10 in the array 1 of microlenses 10. Surface modulation of the modulation surface 11 can thus blur the image IM of the light source 22 formed by a given microlens 10 in the peripheral region of the image IM. In other words, the image IM formed by the microlenses 10 in the array 1 of microlenses 10 is stretched in at least one direction so that at least a portion of the peripheral edge of the image IM is blurred. This stretching can be achieved by surface modulation of the modulation surface 11, which is superimposed on the basic configuration of the modulation surface 11. The basic configuration produces a sharp image IM of the light source 22, while the surface modulation produces a blurred image IM or a blurred portion of the image IM, which is combined with the sharp image IM formed by the basic configuration.

[0044] Therefore, the cylindrical deformation of the image IM projected by at least one light source 22 from all or some of the incident lenses 101 and / or exit lenses 102 of the modified microlens 10 array 10 forms a modulation surface 11, which allows the luminous density in the beam 3 to be modulated. In other words, the modulation surface 11 can produce a gradual decrease in the luminous intensity of the image IM (preferably at its peripheral edges) by blurring certain portions of the image IM. This gradual decrease, unknown in the known array 1 of microlenses 10, then allows the blurred edges of multiple images IM to be juxtaposed to produce a more uniform beam 3 compared to the beams produced by the previously known array 1 of microlenses 10.

[0045] As in Figure 2 As can be seen in beam 3 shown on the right, the light-emitting units formed by the superposition of the images IM of at least one light source 22 together form a more uniform surface in the bottom part of the projected beam FP.

[0046] Specifically, the modulation surface 11 of the array 1 of microlenses 10 now has a specific surface geometry that is different from the geometry of a known array of microlenses 10, such that the image IM of the at least one light source 22 can be deformed in a way that is more conducive to obtaining a more uniform beam 3 and the luminous intensity of the image IM in a portion or even all of its peripheral edges gradually decreases.

[0047] Of course, in the context of this invention, the exact geometry of the surface modulation of the modulation surface 11 can vary depending on the selected modulation function. Therefore, this invention is certainly not limited to simply blurring the peripheral edges of the image IM, but can produce very different distributions of sharp and blurred areas within an image projected by the array 1 of microlenses 10 according to the invention.

[0048] Typically, the association of the modulation surface 11 with a given microlens 10 results in a more complex geometry for the microlens 10: the modulation surface 11, which itself has a complex geometry, is now superimposed on its predetermined and known basic configuration. However, the modulation function can generally be defined by a spatial frequency higher than the spatial frequency of the basic configuration: the basic configuration of the modulation surface 11 defines how it is shaped, for example, to allow a sharp image IM of the light source 22 to be projected to infinity; while the geometry of the modulation surface allows light rays associated with the peripheral edges of the image IM to diverge, thus blurring the peripheral edges. This blurred image IM is formed by surface modulation of the modulation surface 11, which transforms the sharp image IM formed by the basic configuration of the modulation surface 11. Thus, the surface modulation of the modulation surface 11 can be defined, for example, as a change in thickness relative to the basic configuration of the modulation surface 11. This thickness change follows a complex profile, depending on the effect sought in the surface modulation of the modulation surface 11 and the blurring of the peripheral edges of the projected image IM.

[0049] For example, for a given microlens 10, the modulation surface 11 may have one or more local extrema (i.e., one or more convexities and / or one or more concaveities) that cause convex and / or concave portions to exist on the modulation surface 11. The presence (and alternation) of such convex and concave portions causes a relatively large deviation in the light rays RL passing through the modulation surface 11, resulting in an image IM of the light source 22 that is more uniform and more distorted than if such a modulation surface 11 were not present on the array 1 of microlenses 10. In other words, the presence (and alternation) of such convex and concave portions forms surface modulation of the modulation surface, causing stretching of certain portions of the image IM, and especially all or some of its peripheral edges, to produce a more gradual change in its luminous intensity at said peripheral edges (i.e., the peripheral edges affected by surface modulation).

[0050] According to the invention, the blurring produced by surface modulation of the modulation surface 11 can be oriented in a first direction X and / or in a second direction and / or in a third direction. When the surface modulation geometry of the modulation surface 11 produces blurring in the first direction X, the beam 3 will exhibit less discontinuity in luminous intensity along the length of the light-emitting unit forming the projected beam FP and along the first direction X. The first direction X is preferably horizontal or substantially horizontal so that the intensity of the projected beam FP is more uniform across the road scene illuminated by the light-emitting module 2 equipped with the array 1 of microlenses 10 according to the invention. Alternatively or additionally, when the surface modulation geometry of the modulation surface 11 produces blurring in the second direction, the beam 3 will exhibit less discontinuity in luminous intensity along the length of the light-emitting unit forming the projected beam FP and along the second direction. For such a light-emitting module 2 equipped with the array 1 of microlenses 10 according to the invention, the second direction is preferably vertical or substantially vertical so that the intensity of the projected beam FP is more uniform in a direction perpendicular or substantially perpendicular to the cutoff line. Similarly, alternatively or additionally, when the surface modulation geometry of the modulation surface 11 produces blurring in the third direction, the beam 3 will exhibit less discontinuity in luminous intensity along the length of the light-emitting unit forming the projected beam FP, and in both the first and second directions. For such a light-emitting module 2 equipped with an array 1 of microlenses 10 according to the invention, the third direction is preferably inclined so that the intensity of the projected beam FP is more uniform in both the first and second directions. Advantageously, the inclined portion of the third direction is parallel to the cutoff line.

[0051] The choice of whether to produce such blurring in the first and / or second directions in the projected image IM depends in particular on the position of the image IM in the projected beam 3: - If the image IM projected by the microlens 10 is near or even in contact with the horizontal portion of the cutoff line of the beam 3, the blur produced by the surface modulation of the corresponding modulation surface 11 will be oriented only in the horizontal direction of the image IM. - If the image IM projected by the microlens 10 is located at a certain distance from the cutoff line of the beam 3 relative to the vertical axis, the blur generated by the surface modulation of the corresponding modulation surface 11 will be oriented in the horizontal direction and / or the vertical direction of the image IM. If the image IM projected by microlens 10 is located near or even in contact with the inclined portion of the cutoff line of beam 3, the corresponding microlens will not have a modulation surface, and therefore the projected image IM will have neither vertical nor horizontal blur. Alternatively, the corresponding microlens has a modulation surface, and the blur generated by surface modulation of the corresponding modulation surface 11 is oriented only in the inclined directions relative to the horizontal and vertical directions of the image IM, said inclined directions being parallel to the inclined portion of the cutoff line. This configuration allows for improved beam uniformity while maintaining a satisfactory level of sharpness at the inclined portion of the cutoff line.

[0052] According to a particularly advantageous embodiment of the invention, the surface modulation of the modulation surface 11 is obtained by deriving a modulation function that defines the thickness of the surface modulation relative to the basic configuration of the modulation surface 11. Figure 3 The figure illustrates such a modulation function, showing the normalized amplitude ΔZ / Z of the modulation surface 11 in the first direction X and / or the second direction. The modulation function thus allows the thickness ΔZ of the surface of the modulation surface 11 relative to the basic configuration of the modulation surface 11 as a reference to be defined.

[0053] An example of a modulation function is given by the following equation: in: - x is the coordinate of the current point on the modulation profile, and xmin and xmax are the values ​​of this coordinate at the first and second ends of the modulation profile, respectively. The profile is characterized in the characteristic direction of the surface represented by the set of all values ​​of x. - E is the integer part of the following expression within the parentheses; - A is the amplitude of the modulation function ΔZ in millimeters, which is the thickness of the surface modulation added to the basic configuration of the modulation surface, which produces a clear image of the light source in the absence of surface modulation; - n / 2 is the spatial frequency, in mm. -1 ; - p is a positive number that affects the width of the blurred portion of each image IM formed. Specifically, the larger the number p, the larger the unblurred central portion of the image IM of the light source 22 formed by each microlens 10; and - φ is a size parameter chosen between 0 and 1. The smaller the value of φ, the greater the slope of the corresponding modulation function at its local extrema.

[0054] Therefore, in Figure 3 As can be seen from the curve, the modulation function characterizing the modulation surface 11 of the array 1 of the microlens 10 according to the present invention includes: - A first region Z1, which corresponds to the horizontal or substantially horizontal portion of the modulation function. This first region Z1 corresponds to the portion of the incident light ray RL that is not deflected or is only slightly deflected, so that the light ray RL propagates through the modulation surface 11 without diverging. The first region Z1 thus allows the light ray RL to undergo a neutralization transition when forming the image IM of the at least one light source 22; - A second region Z2 corresponds to the portion of the modulation function with the maximum slope. This second region Z2 corresponds to the portion where the incident light ray RL experiences maximum or significant deflection, so that the light ray RL propagates through the modulation surface 11 and converges or diverges towards the lateral region of the light-emitting unit. The second region Z2 thus allows for increasing the width or height of the light-emitting unit to allow for partial superposition of multiple adjacent images IM of the at least one light source 22 without producing a region of higher brightness; - A third region Z3 corresponds to a local extremum of the modulation function, i.e., the region where the tangent of the modulation function is reversed. This third region Z3 corresponds to the portion where the incident ray RL experiences maximum or significant divergence, which ray RL thus propagates through the modulation surface 11 and diverges in several given directions around the local extremum. The third region Z3 thus prevents the image IM from accumulating at the blurred peripheral boundaries caused by surface modulation, which would otherwise result in higher brightness and be detrimental to obtaining a uniform overall beam. For this purpose, the semi-tangents drawn in each third region Z3 advantageously have a large slope.

[0055] Furthermore, it can be seen that, Figure 3 In the example of the illustrated embodiment, the modulation function has a spatial frequency of order L / 3, where L is the size of the image IM that produces the blur, i.e., the length of the horizontal coordinate or "x-axis" profile, because three identical patterns M are periodically repeated between two opposite edges of the modulation surface 11 in the first direction X and / or the second direction Y.

[0056] Finally, according to the first embodiment of the present invention, all microlenses 10 in the array 1 of microlenses 10 include a modulation surface 11, or according to as... Figure 2 In the second embodiment shown schematically, only some microlenses 10 include a modulation surface 11. Furthermore, the modulation surfaces 11 of all microlenses 10 including such a modulation surface 11 may be identical, or they may be different, depending on the desired effect and the contribution of a given microlens 10 to constructing the projected beam FP and its cutoff line.

[0057] Figure 4 , Figure 5 and Figure 6 This allows for a more qualitative and quantitative definition of the modulation surface 11. Specifically: - Figure 4A portion of the known prior art unmodulated surface 11B is shown, which also corresponds to a portion of the basic configuration of the surface of the modulated surface 11 according to the present invention. The x, y, and z axes of the coordinate system are all expressed in millimeters; - Figure 5 This illustrates the method of applying the present invention to... Figure 4 A portion of the modulated surface 11 obtained by adding modulation to the unmodulated surface 11B. The x, y, and z axes of the coordinate system are all expressed in millimeters; It should be noted that, Figure 4 and Figure 5 In this model, the z-axis scale is significantly larger than the x-axis and y-axis scales. This allows for... Figure 5 The modulation of the modulation surface 11 can be clearly seen in the image.

[0058] - Figure 6 Showing Figure 4 and Figure 5 The surfaces shown are Fourier transforms in the same specific direction corresponding to the straight-line profile intercepted along each surface (and more precisely along the segment parallel to the x-axis and located at y = 0). The x-axis represents the spatial frequency, in mm. -1 The units are expressed as y-axis. The y-axis corresponds to the coefficients assigned to the given frequency component in Fourier space. Therefore, along the contour of the Fourier transform calculation, the shape of the modulation surface 11 corresponds to the integral sum of the sine of the given frequency weighted by the corresponding coefficients. It should also be noted that in Figure 6 In the figure, the Fourier transform values ​​near the origin of the x-axis have been truncated. Specifically, the coefficients are greater than 1, which is the maximum value shown to ensure the readability of the curve.

[0059] refer to Figure 4 As can be seen, the unmodulated surface 11B corresponding to the basic configuration of the modulation surface 11 forms a regular geometric shape. The curvature of the basic configuration is generally concave, or generally convex. More specifically, the basic configuration of the modulation surface is either entirely concave or entirely convex. Typically, the basic configuration does not contain abrupt changes in geometry. This regular morphology is reflected in the frequency domain through... Figure 6 The Fourier transform curve TFB shown in the figure defines the basic configuration. It can be seen that the Fourier transform of the basic configuration is a curve that monotonically decreases with increasing spatial frequency. In other words, the geometry of the basic configuration of modulation surface 11 is a surface dominated by long wavelengths (i.e., low spatial frequencies), thus reflecting a smooth and gradual change in the outline of the geometry of the basic configuration.

[0060] In comparison, reference Figure 5As can be seen, the modulation surface 11 forms a more irregular surface and contains abrupt changes in morphology, including very rapid changes in slope and changes in the concavity or convexity of the surface modulation. This highly irregular morphology is reflected in the frequency domain through... Figure 6 The solid line curve TFM of the Fourier transform shown in the figure defines the modulation surface 11. It can be seen that the Fourier transform of the modulation surface 11 is a curve that is generally decreasing but includes multiple large-amplitude peaks superimposed on the decreasing trend of the curve. The overall decreasing characteristic of the surface modulation is related to its superposition on the basic configuration, and the surface modulation corresponds to the long-wavelength structural characteristics of the basic configuration. In the example shown here, the peaks rising above the overall decreasing curve correspond to the fundamental frequency and odd harmonics, i.e., the frequencies of the odd harmonics are odd multiples of the fundamental frequency. Of course, this example is not limiting, and many harmonic distributions can be compatible with the modulation surface 11 of the present invention, especially even harmonics (i.e., the frequencies of even harmonics are even multiples of the fundamental frequency), or both even and odd harmonics.

[0061] Each harmonic defines a spatial frequency representing the modulation surface 11: the first peak value F corresponds to the fundamental frequency of the modulation surface 11, i.e., to the spatial frequency most representative of the modulation of the profile of the modulation surface 11, along which the Fourier transform is calculated. This first peak value here has a position of 5 mm. -1 The maximum value at this point corresponds to a wavelength on the order of approximately 0.2 mm. Advantageously, the fundamental frequency is at 2 mm. -1 (Corresponding to a wavelength of 0.5 mm) and 50 mm -1 (corresponding to a wavelength of 0.025 mm) including the limit values.

[0062] Advantageously, the fundamental frequency of the surface modulation of the modulation surface is less than 50 mm. -1 In Fourier transforms, the fundamental frequency exceeds 50 mm. -1 The peak value does not indicate the invention or surface modulation. Instead, such a peak value would indicate the machining of the microlens surface, such as polishing or milling of the surface, or the imprinting of a mold that allows the surface to be obtained. In contrast, harmonic frequencies exceeding 50 mm -1 The peak value is compatible with the present invention.

[0063] exist Figure 6 In the example illustrating an embodiment of the modulation surface 11 of its Fourier transform, it can be seen that the harmonic is a third-order harmonic (corresponding to peak value H3, with a maximum value at 15 mm). -1 ) and the 5th harmonic (corresponding to peak value H5, with a maximum value at 25 mm). -1 ).

[0064] The Fourier transform obtained for these surfaces along the segments parallel to the x-axis and located at y values ​​other than 0 will be similar to the one referenced above. Figure 6The Fourier transform described above. In contrast, the Fourier transform obtained for the segment parallel to the y-axis will be similar to the Fourier transform described above regarding the basic configuration. Specifically, the modulation of the modulation surface 11 in this example exists only in the x-direction. However, modulation can also occur in the y-direction. Modulation can also occur in both the x- and y-directions.

[0065] In summary, the present invention relates to an array 1 of microlenses 10 for a light-emitting module 2 in a motor vehicle. The array 1 of microlenses 10 is configured to shape light rays RL generated by a light source 22 to generate a projected light beam FP. The array 1 of microlenses 10 includes an incident lens 101 forming an incident surface 104 and an exit lens 102 forming an exit surface 105. The incident lens 101 and the exit lens 102 are paired to form an optical channel 103 configured to project an image IM from the light source 22. The modulation surface 11 of the array 1 of microlenses 10 has a modulation surface 11 superimposed on the basic configuration of the modulation surface to produce a gradual decrease in luminous intensity at the peripheral edges of the thus projected image IM.

[0066] Of course, the present invention is not limited to the examples already described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, various features, forms, variations, and embodiments of the present invention can be associated with each other in various combinations, as long as they are compatible or non-exclusive. In particular, all the above variations and embodiments can be combined with each other.

Claims

1. An array (1) of microlenses (10) for a light-emitting module (2) of a motor vehicle, the array (1) of microlenses (10) being configured to shape light rays (RL) generated by a light source (22) to generate a projected beam (FP), the array (1) of microlenses (10) comprising: - An incident lens (101) including an incident surface (104) configured to receive the light ray (RL), the incident surface (104) of the incident lens (101) forming the incident surface of the array (1) of the microlenses (10); - An exit lens (102) including an exit surface (105) configured to allow the light ray (RL) to exit from the array (1) of the microlenses (10), the exit surface (105) of the exit lens (102) forming the exit surface of the array (1) of the microlenses (10), and an optical channel (103) formed by each incident lens (101) associated with the opposite exit lens (102), the optical channel being configured to generate an image (IM) of the light source (22); The feature is that the modulation surface (11) of the incident surface (104) and / or exit surface (105) of the array (1) of the microlenses (10) selected from the array (1) of the microlenses (10) has surface modulation associated with the basic configuration of the modulation surface (11).

2. An array (1) of microlenses (10) as described in the preceding claim, wherein, The surface modulation of the modulation surface (11) is configured to produce blurring in a first direction (X) in the peripheral region of the image (IM) of the light source (22).

3. An array (1) of microlenses (10) as described in the preceding claim, wherein, The surface modulation of the modulation surface (11) is configured to produce blurring in a second direction in 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) as described in any of the preceding claims, wherein, The surface modulation of the modulation surface (11) has concave and / or convex regions so as to stretch the image (IM) formed by the light source (22) beyond its initial size by generating a peripheral boundary, the luminous intensity of which gradually decreases from the central region of the image to the region outside the image (IM).

5. An array (1) of microlenses (10) as described in any of the preceding claims, wherein, The modulation surface (11) includes at least a portion of the exit surface (105) of the array (1) of the microlenses (10).

6. An array (1) of microlenses (10) as described in any of the preceding claims, wherein, The modulation surface (11) includes at least a portion of the incident surface (104) of the array (1) of the microlenses (10).

7. A light-emitting module (2) for a motor vehicle, the light-emitting module (2) comprising: - At least one light source (22), said at least one light source being configured to produce light (RL); - An array (1) of microlenses (10) as described in any of the preceding claims, wherein the incident surface (104) of the array (1) of microlenses (10) is optically coupled to the at least one light source (22).

8. A light-emitting device for a motor vehicle, the light-emitting device comprising a housing that accommodates a light-emitting module (2) as described in the preceding claim.

Images