Matrix device comprising a plurality of microlenses.

Abstract

Title of the invention: Matrix device comprising a plurality of microlenses. The present invention relates to a matrix device comprising a plurality of microlenses defining a light channel (14) extending along a defined thickness (14), along a longitudinal direction, between an input surface (10) and an output surface (12). The matrix device (2) has at least two adjacent microlenses whose output surfaces (12) are offset in one direction relative to each other, and whose input surfaces (10) of said at least two adjacent microlenses are offset in the same direction relative to each other. The offset between the output surfaces (12) is greater than the offset between the input surfaces (10). Each light channel (14) overlaps an adjacent light channel (14) in the longitudinal direction over an overlap thickness (22) of at least 1 mm. (Figure 2)

Description

Title of the invention: Matrix device comprising a plurality of microlenses.

[0001] The present invention relates to the field of automotive lighting systems, and more particularly to lighting systems equipped with a matrix device formed of a plurality of microlenses and configured to perform at least one lighting and / or signaling function.

[0002] Vehicles, and in particular motor vehicles, are commonly equipped with headlights to generate different light functions, including lighting functions to illuminate a roadway on which the motor vehicle is traveling.

[0003] Conventionally, motor vehicle headlights are equipped with light modules protected by a transparent lens and in which at least one light unit includes means for emitting light rays, optical elements associated with said emission means for collecting and directing said light rays, and at least one projection lens configured to shape these light rays collected and directed by the optical elements and to project them outwards from the headlight and the motor vehicle by forming a regulatory light beam adapted to the performance of the desired light function.

[0004] For stylistic reasons, for example, light modules can be designed to follow certain surfaces of the vehicles they are intended to equip, such as the transparent lens of the projector, through which the beams are intended to pass after exiting the projection lens, or the front of the vehicle. These vehicle surfaces are not always flat, so it is necessary to adapt the light modules to follow these non-planar surfaces. Furthermore, it is also possible to encounter a relatively flat exterior window or front panel and want to create a light module that deviates from it to create an impression of depth. In both cases, the light modules are configured so that their exit face, that is, the face intended to be in contact with the transparent lens or the front panel, has a curved, controlled, and adapted shape.

[0005] In certain applications, one of the aforementioned lighting functions is achieved by emitting light rays from a light source through a microlens array, also known by the English acronym "MLA". A microlens array comprises, in particular, a plurality of microlenses made of a transparent material and Arranged relative to each other to form light channels extending longitudinally between an input surface and an output surface, these channels are respectively focused so that light rays entering a light channel propagate through the microlens array and exit through the output surface associated with that light channel. To enable the formation of a sharp image by the array, the focal lengths of the microlenses are substantially the same from one light channel to the next, resulting in a longitudinal dimension of these channels that is essentially constant across all light channels.

[0006] Where appropriate, a mask may be interposed within each light circulation channel between input microlenses and output microlenses, to cut off the propagation within this channel of some of the light rays focused by an input microlens and to ensure an adequate shape of a beam of light rays at the output of the corresponding light circulation channel of said microlens matrix device.

[0007] It is advantageous to fabricate such a matrix device by plastic injection molding of said transparent material, to allow for the simple and efficient fabrication of each microlens. This plastic injection molding allows for a specific curvature to be imparted to this matrix device, notably by offsetting the exit surfaces of the light channels from one another along the longitudinal direction corresponding to the principal optical axis of this matrix device. In this respect, it is particularly advantageous not to have an interposed mask, as this is made of an opaque glass plate, and this hinders the flexibility of the fabrication.

[0008] The offset of the output surfaces relative to each other along the longitudinal direction makes it possible to form a matrix device with a curve suitable for matching the curve of the vehicle in the area where the light device equipped with the matrix device is to be installed.

[0009] In order to be able to follow pronounced curves, it is necessary to have a significant longitudinal offset between adjacent output surfaces which implies an equally significant longitudinal offset between adjacent input surfaces and helps to create a small overlap zone between two adjacent light channels.

[0010] However, this small longitudinal overlap zone between two adjacent light channels, in a plastic injection context, does not allow for optimal injection because the space available to allow the injected material to flow from one area of ​​the injection mold intended to form a light channel to another area of ​​the injection mold intended to form an adjacent light channel is not sufficient.

[0011] The present invention falls within this context and aims to overcome at least some of the aforementioned drawbacks. In particular, the present invention aims to enable the formation of a matrix device with a shape that can have a complex curve by plastic injection, and in which this plastic injection is carried out optimally regardless of the offset between two adjacent output surfaces of the matrix device.

[0012] Thus, the present invention relates to a matrix device configured to perform optical treatment of light rays emitted towards the matrix device, the matrix device comprising a plurality of microlenses juxtaposed and superimposed with respect to each other, each microlens defining a light channel extending along a defined thickness, along a longitudinal direction, between an inlet surface and an outlet surface of the microlens, the inlet surface being configured to form the surface through which the light rays enter the light channel and the outlet surface being configured to form the surface through which the light rays exit the light channel,the matrix device having at least two adjacent microlenses whose respective exit surfaces are offset in one direction relative to each other along the longitudinal direction and whose respective entrance surfaces are offset in the same direction relative to each other along this longitudinal direction, the offset between the exit surfaces of said at least two adjacent microlenses measured along the longitudinal direction being greater than the offset between the entrance surfaces of said at least two adjacent microlenses measured along this longitudinal direction, each light channel of a microlens overlapping, in the longitudinal direction, a light channel of an adjacent microlens with an overlap thickness of at least 1 mm.

[0013] The array device is a microlens array made of a transparent, injectable material, for example, a plastic material such as PMMA (polymethyl methacrylate) or PC (polycarbonate). The array device comprises a plurality of microlenses, each defining a light channel for propagating incident light rays arriving at the array device. The light channels thus formed extend between an entrance surface opposite a collimator and an exit surface facing outwards from the vehicle. The thickness of the microlenses is measured along the optical axis of the light channel, here a longitudinal axis, between the optical center of the entrance surface and the optical center of the exit surface.

[0014] The light rays arriving at the matrix device enter it via the inlet surfaces of the different light channels, and these inlet surfaces are focused so that the rays propagate within the associated light circulation channel towards the output surface.

[0015] The microlenses are formed continuously from the inlet surface to the outlet surface. More precisely, there is no interposed mask between the inlet surface and the outlet surface.

[0016] The matrix device is also characterized in that the offset of the output surfaces relative to one another, and at least between an output surface and an adjacent output surface, contributes to forming a pronounced curvature of the matrix device, at least over a local portion of this matrix device. This curvature is considered with respect to an envelope passing substantially through a majority of the optical centers of the output surfaces of the microlenses forming the matrix device. More particularly, the marked profile mentioned above is obtained by an offset of the respective output surface of two adjacent microlenses along the longitudinal direction that is greater than the offset between the input surfaces of the microlenses considered along this longitudinal direction.Furthermore, a pronounced curvature profile is observed on the matrix device when the envelope has a small local radius of curvature, and in particular when the envelope combines a plurality of small and distinct radii of curvature.

[0017] The offset of the exit surfaces between two adjacent microlenses is compensated by an adjustment of the thickness of at least one of the two microlenses so that the light channel of one microlens covers the light channel of the other microlens by at least 1 mm.

[0018] The matrix device may include one or more of the following characteristics, taken alone or in combination.

[0019] According to a non-limiting feature of the invention, at least two adjacent light channels whose exit surfaces are offset along the longitudinal direction have different thicknesses. In other words, having a sufficient overlap thickness from one light channel to the other is achieved by increasing the thickness of one of the two light channels, and therefore by increasing the thickness of one or both of the microlenses that form the light channel whose thickness has been increased relative to the thickness of the other light channel.

[0020] According to a non-limiting feature of the invention, the matrix device comprises a first set formed of two adjacent microlenses and a second set formed of two other adjacent microlenses, the first set having a displacement measured along the longitudinal direction between the exit surfaces of the microlenses that differs from a displacement measured along the longitudinal direction between the exit surfaces of the microlenses of the second set.

[0021] It is understood that the matrix device has a distinct curvature from an inclined plane so that some microlenses present their exit surface with a significant offset or clearance relative to the exit surface of the adjacent microlens.

[0022] According to a non-limiting feature of the invention, for each light channel, an image focal plane of the input surface coincides with an object focal plane of the output surface of said light channel. In other words, each microlens of the matrix device is configured so that light rays, having reached an input surface of one of the light channels in a beam rendered substantially parallel, for example by prior passage through a collimator, emerge from said light channel via the output surface in a beam of parallel rays. Thus, the matrix device forms an afocal system. A microlens participating in the formation of a light channel is configured so that the image focus associated with its input surface is substantially in the vicinity of the object focus associated with the output surface of that microlens.

[0023] According to a non-limiting feature of the invention, for each light channel an image focus of the input surface is coincident with an object focus of the output surface of said light channel.

[0024] According to a non-limiting feature of the invention, the inlet surface of the microlenses has a convex shape and the outlet surface of the microlenses has a concave shape.

[0025] The matrix device does not have a mask, so the microlenses must be configured so that the light rays propagate only within their associated light channel, without spilling into an adjacent light channel, and without loss of luminous efficiency. In this context, it is desirable that the image focal points of the input surfaces be located beyond the output surfaces of the light channels. In other words, each input surface of the microlenses is configured to make the light rays converge on the corresponding output surface; that is, configured so that an image focal point of this input surface is substantially positioned on the optical axis at a distance from the input surface greater than the distance between the optical center of the input surface and the optical center of the output surface.

[0026] According to a non-limiting feature of the invention, the matrix device is configured to perform at least one light function, the ratio between an image focal length of the input surface of the microlenses and the object focal length of the output surface of the microlenses for microlenses configured to ensure the same light function is the same to within 10% from one of said microlenses to another of said microlenses.

[0027] This ratio makes it possible to maintain a similar magnification between each microlens performing the same light function, regardless of the thickness of each microlens. This is particularly important here since at least some of the microlenses involved in forming light channels have a different thickness than other microlenses involved in forming an adjacent light channel. By maintaining a ratio between the image focal length of the input surface and the object focal length of the output surface within ±10%, we ensure that the magnification produced by each microlens performing the same light function, even though these microlenses may have different thicknesses, is substantially the same. This allows us to obtain a homogeneous overall light beam, formed by all the light beams from said microlenses.

[0028] It should be noted that microlenses configured to perform the same light function are similar to microlenses configured to perform the same anamorphosis of the image of the light source.

[0029] According to a non-limiting feature of the invention, the overlap thickness of a light channel of one microlens with another light channel of an adjacent microlens is constant within ±0.5 mm of the matrix device. This constant overlap thickness optimizes the plastic injection molding process for forming the matrix device by generating a material flow zone within the mold that is constant from one microlens to the next. The material thus flows at substantially the same speed, and a substantially equivalent amount of material is present in the flow zones, ensuring uniform cooling of the material throughout the matrix device and resulting in a more homogeneous final structure.It should be noted that this consistency in the overlap thickness, within ±0.5 mm, is measured in increments of 0.5 mm in a first direction along the longitudinal axis and 0.5 mm in a second direction opposite to the first along the longitudinal axis, such that the delta of the variation is at most 1 mm. In other words, across the entire matrix device, the difference between the largest and smallest overlap thicknesses is less than or equal to 1 mm. Naturally, this consistency of the overlap thickness of ±0.5 mm is consistent with the feature of the invention according to which the overlap thickness is at least 1 mm.

[0030] According to a non-limiting feature of the invention, the coating thickness gradually evolves from the minimum to the maximum from a zone of the matrix device or the thickness, along the longitudinal direction, of the light channel is the smaller towards an area of ​​the matrix device or the thickness, along a longitudinal direction, of the light channel is the greatest.

[0031] According to a non-limiting feature of the invention, the covering thickness is constant over the entire matrix device.

[0032] According to a non-limiting feature of the invention, each light channel of the microlenses forms a volume defined by its thickness, a height corresponding to a direction perpendicular to the direction of the thickness, and a width corresponding to a direction perpendicular to both the direction of the thickness and the direction of the height, the height and width of the light channel being less than or equal to 10 mm. Such dimensions of the microlenses make it possible to limit the mass of the array device. Preferably, the height and width of the light channel are greater than or equal to 0.3 mm. Thus, the array device can be obtained by a simple injection molding process. More preferably, the height and width of the light channel are between 1 mm and 5 mm. These dimensions make it possible to obtain microlenses whose size is small enough not to be distinguished at the usual viewing distance.It should be noted that the height and width of the microlenses remain constant to within plus or minus 10% along the thickness of the light channel.

[0033] According to a non-limiting feature of the invention, at least some of the light channels are produced during a single injection pass. This single injection pass is part of an injection process that can produce all the light channels so that all the light channels are formed in one continuous operation. In other words, this aspect of the injection process is characterized by a single injection step during which the material is injected through a single orifice and then spreads uniformly inside a mold to form the matrix device. Such an injection process simplifies the manufacture of the matrix device. The injected plastic material is transparent or translucent, and by way of non-limiting example of the invention, this plastic material can be polymethyl methacrylate (PMMA) or polycarbonate (PC).Alternatively, this same injection pass can allow the creation of at least some light channels which have previously been partially created using another material, for example an opaque material suitable for forming occulting areas, and these light channels are then finalized in the same injection operation of a transparent or translucent plastic material of the PC / PMMA type for the creation of the optical part.

[0034] According to a non-limiting feature of the invention, at least some of the light channels, in particular all the light channels, are made by several injection passes of the same material, each injection pass making it possible to make a part of the thickness of said channels. This makes it possible, for example, to manufacture, with limited time and good precision, a matrix device whose light channels are of great thickness.

[0035] The present invention also relates to a light module for equipping a motor vehicle, comprising at least one light emission assembly, at least one collimator disposed opposite the light emission assembly, the light emission assembly comprising at least one light source configured to emit a set of light rays towards the collimator, the collimator being configured to direct the light rays into a beam of rays substantially parallel to each other, and at least one matrix device according to the present invention, the matrix device being disposed opposite the collimator so that the beam of parallel rays is directed onto the input surface of the matrix device.

[0036] The light module according to the invention is intended to equip a motor vehicle for the performance of at least one lighting function, the light beam generated by the light module for the purpose of performing this lighting function being projected along an optical axis of the light module.

[0037] The light module comprises one or more light sources designed to emit light rays towards a collimator. The collimator transforms the light rays emitted by the light source and directs them towards the matrix device into a beam of parallel incident light rays. The incident light rays arriving at the matrix device are more precisely parallel, with the exception of divergences related to the dimensions and parameters of the various elements forming the light module.

[0038] It should also be noted that the expression "substantially parallel" means that the beam directed towards the matrix device may have an angular opening due in particular to the size of the light source, and to the focal length of the collimator and where applicable to manufacturing tolerances.

[0039] According to a non-limiting feature of the invention, at least some or all of the microlenses of the matrix device are configured to project an anamorphic image of the light source to form an overall light beam performing a lighting function. Within the matrix device, some microlenses can project images having the shape and proportions of at least one light source. Indeed, such images may not be an anamorphosis of the at least one light source but may simply be more or less enlarged and / or angularly shifted within the projected light beam. Alternatively, each microlens can project an anamorphic image of at least one light source, that is to say, presenting a shape and / or proportions different from at least one light source.

[0040] According to a non-limiting feature of the invention, each microlens of the matrix device is configured to perform the same anamorphic transformation of the image of the light source. This anamorphic transformation results in a magnification corresponding to the transformation of the size of the light source into a more or less significant angular separation in the light beam. By maintaining the same magnification for microlenses performing the same lighting function, it is ensured that the overall light beam obtained by the sum of the light beams produced by each microlens performing the same lighting function is homogeneous.

[0041] According to a non-limiting feature of the invention, the object focal length of the exit surface of a microlens is at least equal to the thickness of the light channel of said microlens divided by a magnification of an image of the light source projected by said microlens.

[0042] The light module forms an afocal system. To maintain this property of the light module, the image focal plane of the input surface and the object focal plane of the output surface of the same microlens must be substantially coincident. Furthermore, the magnification produced by the microlens is equal to the ratio between the image focal length of the input surface and the object focal length of the output surface. In a context where the focal planes are positioned outside the light channel arranged between the input and output surfaces, with the image focal length of the input surface being strictly greater than the thickness of the microlens in question, it follows that the object focal length of the output surface is at least equal to the ratio of the thickness of the microlens in question to the magnification produced by that microlens.

[0043] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings on the other hand, in which:

[0044] [Fig.1] schematically represents a general view of a matrix device according to the present invention, the matrix device having a complex shape;

[0045] [Fig.2] schematically represents a plan view of a superposition of microlenses of the matrix device highlighting a shift along a longitudinal direction between certain exit surfaces of the microlenses;

[0046] [Fig.3] schematically represents a detailed view of two microlenses adjacent exhibiting different thicknesses and different image and object focal lengths;

[0047] [Fig.4] schematically represents the emission of light rays emitted by a light source and rectified by a collimator towards the matrix device.

[0048] The features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0049] In the detailed description that follows, the terms "longitudinal," "transverse," and "vertical" refer to the orientation of a light channel of the matrix device according to the invention. A longitudinal direction corresponds to a thickness of a light channel of the matrix device, this thickness being parallel to a longitudinal axis L of a frame L, V, T illustrated in the figures. A vertical direction corresponds to a height of the light channel corresponding to an axis of superposition of the microlenses of the matrix device, this axis of superposition being parallel to a vertical axis V of the frame L, V, T, this vertical axis V being perpendicular to the longitudinal axis L. Finally, a transverse direction corresponds to an axis of juxtaposition of the microlenses, this axis of juxtaposition being parallel to a transverse axis T of the frame L, V, T, this transverse axis T being perpendicular to the longitudinal axis L and to the vertical axis V.The vertical axis V and the transverse axis T can, in particular, correspond respectively to the vertical and transverse directions when the matrix device is in its normal position and orientation of use.

[0050] Figure 4 schematically illustrates a general view of a matrix device 2 according to the invention. The matrix device 2 is configured to perform optical processing of light rays emitted towards the matrix device 2. This optical processing of the light rays makes it possible to form at least one lighting and / or signaling function.

[0051] For this purpose, the matrix device 2 comprises a plurality of microlenses 4 juxtaposed next to each other along a juxtaposition axis 6 and superimposed one above the other along a superposition axis 8, as can be seen in particular in [Fig.2].

[0052] The matrix device 2 is intended to equip a light module 1, itself intended to equip a motor vehicle. The light module 1 comprises at least one light emission assembly 3, the matrix device 2, and a collimator 5. arranged on the one hand, with regard to the light emission assembly 3 and on the other hand, with regard to the matrix device 2.

[0053] In the embodiment shown in [Fig. 4], the light-emitting assembly 3 comprises a support 7, here a printed circuit board, on which at least one light source 9 is mounted. The at least one light source 9 is configured to generate light beams 11 in a plurality of directions. The collimator 5 is configured around an optical axis and deflects the light beams 11 emitted by the light source 9 so that all the light beams are directed substantially parallel to the optical axis of the collimator 5 in the direction of the matrix device 2.

[0054] It is understood that the light rays redirected by the collimator 5 towards the matrix device 2 are substantially parallel to each other. It should be noted that the light module 1 can comprise a plurality of light sources 9 and a plurality of collimators 5 so that the matrix device 2 is capable of generating a plurality of lighting functions, in particular via specific control of the activation of one or another light source.

[0055] The light rays 21 redirected by the collimator 5 and reaching the matrix device 2 enter the microlenses 4 through an entrance surface 10 of said microlenses 4 and exit the microlenses 4 through an exit surface 12 of said microlenses 4. Passing through the different optical surfaces of the microlenses 4, i.e., the entrance surface 10 and the exit surface 12, the light rays are optically processed so that the matrix device 2 projects an anamorphic image of at least one light source to form at least one overall light beam providing a given light function. This overall light beam is obtained by the summation of the light beams formed by the microlenses 4 associated with the same light function.

[0056] It should be noted that in the embodiment shown, at least some of the microlenses 4, or alternatively all of the microlenses 4, of the matrix device 2 are configured to perform the same anamorphosis of the image of the light source. More precisely, this anamorphosis results in a transformation of the dimensions of the light source into a greater or lesser spacing in the light beam formed by each microlens 4. Thus, the light function produced by these microlenses 4 is homogeneous.

[0057] We will now describe in more detail the matrix device in relation to figures 2 to 4.

[0058] The matrix device 2 is formed by a plastic injection process in which a transparent plastic or thermoplastic material, such as polycarbonate, is injected into a mold with an appropriate shape according to the light function(s) that one wishes to achieve by means of matrix device 2.

[0059] More specifically, this plastic injection process allows the matrix device 2 to form a single-material element produced in a single plastic injection. This injection process results in a continuity of material between each microlens 4 of the matrix device 2, thus avoiding the formation of a demarcation between two adjacent light channels, which would be inherent in manufacturing these channels in several stages. The absence of such a demarcation avoids the potential risk that it might not be planar, and that the presence of a demarcation encroaching on one of the light channels could lead to local inhomogeneity in the light function provided by the matrix device 2.

[0060] Furthermore, the matrix device 2 is here devoid of a mask interposed between the entrance surface 10 of a microlens 4 and its exit surface 12.

[0061] The implementation of this injection method is part of obtaining a matrix device 2 with a complex curve, that is, a curve that evolves when considering at least one particular direction. This curve forms the profile of the matrix device 2 at the exit surfaces 12 of the microlenses 4. To this end, the curve passes through the center of each of the exit surfaces 12 of the microlenses 4, this center of the exit surfaces 12 being considered as the optical center of the exit surface 12 under consideration. As illustrated in [Fig. 2], the curve can be evolving insofar as the overlap thickness tends to increase non-linearly as one moves along at least one direction, here along the vertical direction. As illustrated in [Fig.[3], the curve can be evolving insofar as the thickness tends to increase and then decrease as one moves along at least one direction, here along the vertical direction.

[0062] Figure 2 schematically represents a more detailed view of a superposition of microlenses 4 of a matrix device 2 according to a particular embodiment of the matrix device 2. This view of the matrix device 2 schematically highlights the superposition of the microlenses 4 with respect to each other along the superposition axis 8. However, the description that follows relating to the superposition of the microlenses 4 along the superposition axis 8 applies mutatis mutandis to the juxtaposition of the microlenses along the juxtaposition axis 6.

[0063] As can be seen in [Fig. 2], each microlens 4 defines a light channel 14 extending along a thickness 16, that is, in a longitudinal direction parallel to the longitudinal axis L, between the entrance surface 10 and the exit surface 12 of the microlens 4 in question. It should be noted that these light channels 14 are also shown in image form in [Fig. 1].

[0064] As mentioned previously, the entrance surface 10 of the microlenses 4 forms the surface through which the light rays emitted by the light-emitting assembly enter the microlens 4. The exit surface 12 forms the surface through which the light rays exit the microlens 4, having been shaped to contribute to the formation of the overall light beam. It should be noted that in an alternative embodiment of the invention, a microlens 4 of the matrix device 2 may comprise a plurality of entrance surfaces 10 and / or a plurality of exit surfaces 12.

[0065] To form a complex curve of the matrix device 2, the exit surfaces 12 of two adjacent microlenses 4 are offset from one another along the thickness 16 of the microlenses 4, that is to say along the longitudinal direction, by a dimension, equal to an overlap thickness 22, which is different from the corresponding overlap thickness 22 that exists between two other exit surfaces 12 of two other adjacent microlenses 4.

[0066] It should be noted that this offset of a microlens 4 with an adjacent microlens 4 along the thickness 16 of the microlenses 4 can be observed as seen in [Fig.2], i.e. in a plane extending parallel to the longitudinal axis L and the vertical axis V. Moreover, an offset similar to that seen in [Fig.2] can be observed in a plane extending parallel to the longitudinal axis L and the transverse axis T.

[0067] In other words, considering the superposition axis 8, at least two adjacent microlenses 4 of the matrix device 2 have an offset between their respective exit surfaces 12 along the thickness 16. Furthermore, considering the juxtaposition axis 6, at least two adjacent microlenses 4 of the matrix device 2 have an offset between their respective exit surfaces 12 along the thickness 16.

[0068] More specifically, the offset between the exit surfaces 12 of two adjacent microlenses 4 along the longitudinal direction is greater than the offset between the entrance surfaces 10 of said microlenses 4 along the longitudinal direction, the two offsets being in the same direction. Furthermore, the microlenses 4 have a lateral dimension 18 which is a dimension extending from edge to edge of the light channel 14 and is perpendicular to the thickness 16 of the light channel 14. In the embodiment shown, this lateral dimension 18 corresponds to the height of the light channel 14 and is measured parallel to the overlap axis 8. It should be noted that in an alternative embodiment of the invention, the lateral dimension 18 may correspond to the width of the light channel 14 and is measured parallel to the juxtaposition axis 6.Moreover, in the case of a microlens 4 with a circular cross-section for example, the width and height respectively form the most . large dimension of the microlens 4 measured parallel to the juxtaposition axis 6 and the superposition axis 8. Moreover, the height and width are constant throughout the thickness 16 of the microlens 4.

[0069] It is understood that each light channel 14 of the microlenses 4 forms a volume defined by the thickness 16, the height corresponding to a direction perpendicular to the direction of the thickness 16, and here corresponding more precisely to the lateral dimension 18, and the width corresponding to a direction perpendicular to the direction of the thickness 16 and to the direction of the height. The height and width of the light channel 14 are less than 10 mm. Preferably, the height and width of the light channel 14 are greater than 0.3 mm. More preferably, the height and width of the light channel 14 are between 1 mm and 5 mm.

[0070] In [Fig. 2], a hypothetical arrangement of microlenses with an equal primary thickness 21 from one microlens 4 to the next for the same offset between their exit surfaces 12 has been represented by dashed lines for ease of understanding. It is particularly noteworthy that when each microlens 4 of the matrix device 2 has the same primary thickness 21, a primary overlap area 20 between two light channels 14 of two adjacent microlenses 4 can be relatively small depending on the offset between the exit surfaces 12 of said microlenses 4.

[0071] This small primary overlap zone 20 does not allow optimal circulation of the injected material between two adjacent microlenses 4 during the implementation of the injection process. Indeed, below a certain overlap value between one light channel 14 and another adjacent light channel 14, the injected material is constrained and the injection to form the matrix device 2 is degraded.

[0072] Also, to allow optimal injection, according to the invention, each light channel 14 of a microlens 4 overlaps in the longitudinal direction a light channel 14 of an adjacent microlens 4 over an overlap thickness 22 of at least 1 mm. Such an overlap thickness 22 makes it possible to form in the mold used to make the matrix device 2 sufficient spaces to allow a homogeneous distribution of the injected material throughout the mold with a single injection step.

[0073] This overlap thickness 22 is obtained by shifting the position of the entrance surface 10 of one of the microlenses 4 along the longitudinal direction. More precisely, this shift of the entrance surface 10 of one of the microlenses 4 corresponds to an increase in the primary thickness 21 until a final thickness 16 of the microlens 4 is obtained, which can therefore differ from the final thickness of the adjacent microlens 4 if the latter is not modified.

[0074] Furthermore, the primary thickness 21 is increased without changing the position of the exit surface 12 of the microlens 4 so that the curvature of the matrix device 2 is not impacted by the change in the thickness 16 of the microlens 4. In other words, the increase in the thickness 16 of a microlens 4 is considered by changing the position along the longitudinal direction of only the inlet surface 10.

[0075] It is particularly notable on [Fig.2], that the modification of the thickness of a microlens 4 to go from the primary thickness 21 to a final thickness 16 is a function of the overlap thickness 22. In other words, if the distance over which an initial overlap thickness extends is less than a minimum value that is desired for the final overlap thickness 22, then the primary thickness 21 of the microlens is increased so that the final overlap thickness 22 is equal to the initial overlap thickness plus the distance over which the thickness of the microlens 4 was modified to go from the primary thickness 21 to the final thickness 16.

[0076] Furthermore, to ensure a homogeneous distribution of the injected material during the injection step, the overlap thickness 22 of a light channel 14 of a microlens 4 of another light channel 14 of an adjacent microlens 4 is constant to plus or minus 0.5 mm within the matrix device 2. Such constancy in the overlap thickness 22 within the matrix device 2 helps to ensure a homogeneous distribution of the injected material and in particular to ensure that the polymerization of the injected material in the mold is substantially uniform.

[0077] Thus, as seen in [Fig.2], a deviation 24 measured along the longitudinal direction between the actual position of the input surface 10 and a primary position 26, visible in dotted lines and corresponding to a fictitious position where each microlens has the same primary thickness 21, of said input surface 10 for the same microlens 4 can be different between two adjacent microlenses 4.

[0078] The value of the gap 24 is a function of the primary overlap 20 between two adjacent light channels 14. Indeed, in order to obtain a constant overlap thickness 22, the smaller the primary overlap 20 measured along the longitudinal direction, the larger the value of the gap 24 will be.

[0079] This value of the gap 24 can also be appreciated with regard to the distance of the offset between two adjacent output surfaces 12 measured along the longitudinal direction so that the greater the distance of the offset and the greater the value of the gap 24 will be and therefore the greater the thickness 16 of the microlens 4 whose output surface 12 is furthest away, along an optical axis of the microlens 4, from the light source will be.

[0080] This offset between two exit surfaces 12 of two adjacent microlenses 4 is particularly noticeable between a first set 28 formed of two adjacent microlenses 4 and a second set 30 formed of two other adjacent microlenses 4. A first offset 32 ​​measured along the longitudinal direction between the exit surfaces 12 of the microlenses 4 of the first set 28 is different from a second offset 34 measured along the longitudinal direction between the exit surfaces 12 of the microlenses 4 of the second set 30.

[0081] More precisely, the first offset 32 ​​extends along the longitudinal direction over a shorter distance than the second offset 34. This variation between the first offset 32 ​​and the second offset 34 contributes to the formation of the complex curvature of the matrix device 2. Moreover, it is noteworthy that the larger the offset, that is, the greater the distance over which the offset extends, the larger the value of the gap 24. Or, in other words, the larger the offset, the greater the thickness 16 of one of the two adjacent microlenses 4.

[0082] When a misalignment between two exit surfaces 12 of two light channels 14 requires adapting the thickness 16 of one of the microlenses so that the overlap thickness 22 is, in accordance with the present invention, at least 1 mm, then the microlens 4 whose exit surface 12 is arranged most outwards along the longitudinal direction, along a direction of the optical axis of the microlens, has its thickness 16 adapted.

[0083] It should be noted that when considering two adjacent microlenses 4, the microlens 4 whose exit surface 12 is furthest from the associated light source is the microlens 4 which has the exit surface 12 which is arranged furthest outwards.

[0084] To maintain homogeneity in the projection of the image of the light source by the microlenses 4, it is possible to modify the configuration of the entrance surface 10 and the exit surface 12 of the microlenses 4 whose longitudinal dimension has been modified relative to that of the other microlenses 4, as will be described in more detail with reference to [Fig. 3]. [Fig. 3] schematically represents a detailed view of two adjacent microlenses 4, highlighting ray tracings consistent with what has been described previously. Thus, as can be seen in [Fig. 3], light rays redirected 36 by a collimator reach the entrance surface 10 of the microlenses 4.

[0085] The entrance surface 10 of a microlens 4 has a convex shape that allows the redirected light rays 36 to be directed towards an image focal plane 38. The convex shape of said microlens 4 is seen by observing the entrance surface 10 of the microlens 4 from outside the matrix device 2. More Specifically, the convex shape of the input surface 10 presents a curved shape oriented outwards from the light channel 14 associated with said microlens 4. The image focal plane 38 corresponds to a plane passing through the image focus of the input surface 10 and perpendicular to an optical axis 40 specific to each microlens 4. The optical axes 40 of the microlenses of the matrix device 2 are substantially parallel to each other. Furthermore, the optical axis 40 associated with a microlens 4 passes through the optical center of the input surface 10 and through the optical center of the output surface 12.

[0086] The output surface 12 of a microlens 4 has a concave shape that allows the light rays redirected 36 by the collimator 5 to pass through the input surface 10 and are then directed towards an object focal plane 39 parallel to each other at the output surface 12. The concave shape of said microlens 4 is considered by observing the output surface 12 of the microlens 4 from outside the matrix device 2. More specifically, the concave shape of the output surface 12 has a convex shape oriented towards the interior of the light channel 14 associated with said microlens 4. The object focal plane 39 corresponds to a plane passing through the object focus of the output surface 12 and perpendicular to the optical axis 40 of the microlens 4.

[0087] The image focal plane 38 and the object focal plane 39 associated with the same microlens 4 coincide. Thus, the image focus of the input surface 10 is positioned at the object focal plane 39, and the object focus of the output surface 12 is positioned at the image focal plane 38. In other words, this specific construction of the matrix device 2 makes it possible to form an afocal system in which the image focus of the input surface 10 coincides with the object focus of the output surface 12, so that the light rays exiting a microlens 4 are substantially parallel to each other. This parallelism between the light rays exiting a microlens 4 makes it possible to define an angular separation 42 between the two light rays furthest apart on either side of the optical axis of the microlens 4.

[0088] As mentioned previously, modifying the thickness 16 of a microlens 4 to obtain a sufficient overlap thickness 22 for optimal plastic injection of the matrix device 2 implies a modification of the position of the image and object focal planes 38, 39 according to the modification of the thickness 16 of the microlens 4 made.

[0089] Indeed, in order to preserve the properties of the afocal system with the angular separation 42 of the light beam produced by each microlens 4, participating in the production of the same overall light beam, substantially constant for each microlens 4, the image focal length 44 measured along the longitudinal direction between the optical center of the entrance surface 10 and the image and object focal planes 38, 39 and the object focal length 46 measured along the longitudinal direction between the optical center of the output surface 12 and the image and object focal planes 38, 39 must maintain a substantially constant ratio for each microlens 4 participating in the realization of the same light function.

[0090] More specifically, the ratio between the image focal length 44 of the input surface 10 of the microlenses 4 and the object focal length 46 of the output surface 12 of the microlenses 4 for microlenses 4 configured to ensure the same luminous function is the same to within 10% of one of said microlenses 4 to another of said microlenses 4.

[0091] This ratio is defined as a function of the thickness 16 of the microlens 4 considered and the magnification of the image of the desired light source, such that the image focal length 44 is always greater than the thickness 16 of the light channel 14 of the microlens 4, and the object focal length 46 is at least equal to the thickness 16 of the microlens 4 divided by the desired magnification. It should be noted that the magnification corresponds to the transformation of the size of the light source into a more or less significant angular separation in the light beam formed by a microlens 4.

[0092] This ratio can be defined by the following relationship:

[0093] x = £2

[0094] With: F' 1: Focal length image 44. F2: Object focal length 46. X: Magnification.

[0095] The ratio between the image focal length 44 and the object focal length 46 allows the positioning of the focal plane 38 relative to the respective optical center of the entrance surface 10 and the exit surface 12 to be defined as a function of the thickness 16 of the microlens 4.

[0096] In order to adjust the position of the image and object focal planes 38, 39 to obtain the aforementioned ratio, the convex and concave shapes of the input surface 10 and output surface 12, respectively, are modified to achieve the desired position of the image and object focal planes 38, 39. It should be noted that this modification of the input surface 10 and output surface 12 is carried out in such a way as to preserve the properties of an afocal system. In other words, the modification(s) made to the input surface 10 and output surface 12 are such that the image focal plane 38 always coincides with the object focal plane 39.

[0097] It is understood that this modification of the outlet surface 12 and the inlet surface 10 is achieved by adapting the shape of the mold so that the plastic material injected which comes into contact with the walls of the mold corresponding to the inlet surfaces 10 and outlet surfaces 12 takes the desired shape allowing to obtain the desired optical properties for the inlet surface 10 and the outlet surface 12 of each microlens 4.

[0098] It is noteworthy here, as mentioned previously, that the propagation of the plastic material within the mold during the injection operation is homogeneous, without jerks, due to the presence of sufficient overlap thicknesses 22, and that this makes it possible to ensure that the plastic material is correctly deposited on the walls of the mold to form the optical surface to the desired quality.

[0099] In other words, it is possible here to modify the thickness 16 of a microlens 4 to obtain a covering thickness 22 sufficient for carrying out the injection process while retaining the properties of an afocal system with a common magnification for each microlens 4 and therefore a clear and homogeneous overall light beam.

[0100] The present invention achieves its intended purpose by proposing a matrix device with a complex shape and the properties of an afocal system. However, the present invention is not limited to the means and configurations described and illustrated herein, and also extends to any equivalent means and configuration, as well as to any technically feasible combination of such means.

Claims

Demands

1. Matrix device (2) configured to perform optical processing of light rays (36) emitted in the direction of the matrix device (2), the matrix device (2) comprising a plurality of microlenses (4) juxtaposed and superimposed with respect to each other, each microlens (4) defining a light channel (14) extending along a defined thickness (14), along a longitudinal direction, between an inlet surface (10) and an outlet surface (12) of the microlens (4), the inlet surface (10) being configured to form the surface through which the light rays enter the light channel (14) and the outlet surface (12) being configured to form the surface through which the light rays exit the light channel (14),the matrix device (2) having at least two adjacent microlenses (4) whose respective exit surfaces (12) are offset in one direction relative to each other along the longitudinal direction and whose respective entrance surfaces (10) are offset in the same direction relative to each other along this longitudinal direction, the offset between the exit surfaces (12) of said at least two adjacent microlenses (4) measured along the longitudinal direction being greater than the offset between the entrance surfaces (10) of said at least two adjacent microlenses (4) measured along this longitudinal direction, each light channel (14) of a microlens (4) overlapping, in the longitudinal direction, a light channel (14) of an adjacent microlens (4) with an overlap thickness (22) of at least 1 mm.

2. Matrix device (2) according to claim 1, comprising a first set (28) formed of two adjacent microlenses (4) and a second set (30) formed of two other adjacent microlenses (4), the first set (28) having a shift measured along the longitudinal direction between the exit surfaces (12) of the microlenses (4) different from a shift measured along the longitudinal direction between the exit surfaces (12) of the microlenses (4) of the second set (30).

3. Matrix device (2) according to any one of claims 1 and 2, wherein for each light channel (14) a focal plane image (38) of the input surface (10) is coincident with an object focal plane (39) of the output surface (12) of said light channel (14).

4. Matrix device (2) according to any one of claims 1 to 3, wherein the inlet surface (10) of the microlenses (4) has a convex shape and the outlet surface (12) of the microlenses (4) has a concave shape.

5. Matrix device (2) according to any one of claims 1 to 4, configured to perform at least one light function, the ratio between an image focal length (44) of the input surface (10) of the microlenses (4) and the object focal length (46) of the output surface (12) of the microlenses (4) for microlenses (4) configured to perform the same light function is the same to within ±10% from one of said microlenses (4) to another of said microlenses (4).

6. Matrix device (2) according to any one of claims 1 to 5, wherein at least two adjacent light channels (14) whose exit surfaces (12) are offset along the longitudinal direction have different thicknesses (16).

7. Matrix device (2) according to any one of claims 1 to 6, wherein the overlap thickness (22) of a light channel (14) of a microlens (4) of another light channel (14) of an adjacent microlens (4) is constant to plus or minus 0.5 mm within the matrix device (2).

8. Matrix device (2) according to any one of claims 1 to 7, wherein each light channel (14) of the microlenses (4) forms a volume defined by the thickness (16), a height corresponding to a direction perpendicular to the direction of the thickness (16) and a width corresponding to a direction perpendicular to the direction of the thickness (16) and to the direction of the height, the height and width of the light channel (14) being less than or equal to 10 mm.

9. Matrix device (2) according to any one of claims 1 to 8, wherein at least some of the light channels (14) are made during the same material injection pass.

10. A light module for equipping a motor vehicle, comprising at least one light-emitting assembly (3), at least one collimator (5) disposed opposite the light-emitting assembly (3), the light-emitting assembly (3) comprising at least one light source (9) configured to emit a set of light rays (11) in the direction of the collimator (5), the collimator (5) being configured to direct the light rays (11) into a beam of rays substantially parallel to each other, and at least one matrix device (2) according to any one of claims 1 to 9, the matrix device (2) being arranged opposite the collimator (5) so that the beam of parallel rays is directed onto the inlet surface (10) of the matrix device (2).

11. Light module according to claim 10, wherein at least some microlenses (4) of the matrix device (2), or all of the microlenses (4) of the matrix device (2), are configured to project an anamorphic image of the light source (9) to form an overall light beam providing a light function.

12. Light module according to claim 11, wherein each microlens (4) of the matrix device (2) is configured to perform the same anamorphosis of the image of the light source (9).

13. Light module according to any one of claims 10 to 12, wherein the object focal length of the exit surface (12) of a microlens (4) is at least equal to the thickness (16) of the light channel (14) of said microlens (4) divided by a magnification of an image of the light source (9) projected by said microlens (4).

Images