OPTICAL PROJECTION SYSTEM AND LIGHTING MODULE FOR A VEHICLE

Description

[0001] The present invention relates in particular to an optical projection system and a vehicle lighting module.

[0002] A preferred application is in the automotive industry, for vehicle equipment, particularly for the creation of devices capable of emitting light beams, also known as lighting and / or signaling functions, generally complying with regulations. For example, the invention can enable the production of a segmented light beam, notably for use in front-end vehicle lighting and / or potentially signaling functions.In particular, the invention can enable the generation of a supplementary high beam (associated with a basic beam totally or at least predominantly projected below a horizontal cut-off line of the type used for the dipped beam function, the supplementary high beam being added to the basic beam so as to complete it above the cut-off line; advantageously, this supplementary high beam is adaptive to turn on or off certain parts of the overall projected beam, for example for anti-glare functions.

[0003] Vehicle signal and / or lighting devices are lighting systems that include one or more light sources and a lens that closes the light. In simple terms, the light source emits light rays to form a beam that is directed towards the lens, which then transmits the light to the outside of the vehicle. These functions must comply with regulations, particularly regarding light intensity and visibility angles.

[0004] The lighting modules known to date are designed to emit light fulfilling a lighting function, for example: a dipped beam, mostly directed downwards (there are usually minority parts of the beam which are upwards and which illuminate above the horizon), sometimes still called a dipped beam and used when other vehicles are present on the roadway; a main beam without a cut-off, and characterized by maximum illumination in the axis of the vehicle; a fog light beam, characterized by a flat cut-off and a large illumination width.

[0005] These functions typically relate to a forward projection.

[0006] Recently, technologies have been developed to produce a segmented, also called pixelated, beam for adaptive lighting functions, such as those described in UNECE Regulation 123. This is particularly relevant for a "highway supplement" lighting function, generally based on multiple lighting units, each containing a light-emitting diode (LED), which can be individually controlled. The beam, resulting from the different beam segments produced by each diode, is projected using an optical projection system that typically includes one or more lenses.

[0007] In this description, a segmented beam is defined as a beam whose projection forms an image composed of beam segments, each segment of which can be illuminated independently. A pixelated light source can be used to form these segments.

[0008] In some cases, particularly in floor-based writing applications using digital micromirror arrays (DMDs), the pixel count is exceptionally high (over 100,000 pixels), and the projection optical system does not require a large numerical aperture. However, the use of high-resolution technologies (over 100,000 pixels) significantly impacts the final cost of the lighting system. To achieve a pixelated, glare-free beam over a wide area, a large numerical aperture is desirable. At the same time, a large aperture must not compromise the quality of the emitted beam, particularly in terms of chromatic aberration.

[0009] The present invention aims to remedy at least partially this problem.

[0010] A cinematographic projection system is known from patent US2003 / 0112525. The projection lens comprises a lens assembly forming a so-called double Gauss structure, preceded upstream by a field lens and downstream by a Fraunhofer-type doublet lens. However, this system has a small aperture (1:1.9 or f / 1.9) and a significant size (between 100 and 400 mm), resulting in low flux efficiency and mechanical integration difficulties for applications in automotive lighting. The invention aims to provide an efficient and compact optical system for automotive lighting modules.

[0011] The invention is defined by the claims.

[0012] Thanks to the lens combination of the invention, the optical system provides a large numerical aperture, i.e., with an aperture number N<1. In particular, the input optical group functions as a field lens, increasing this aperture. Furthermore, the plurality of lenses allows for a precise selection of materials, such as glass, particularly for adjusting chromatic aberration corrections; chromatic aberration control is especially important for adaptive beam applications where the contrast within the beam is high (between illuminated and unilluminated areas). Moreover, this lens combination ensures a compact optical system, advantageously less than 75 mm along the optical axis. Finally, this lens combination has the advantage that the system's exit pupil is located on the outermost diopter and therefore does not require a diaphragm.

[0013] In a preferred case, the lighting module participates in dipped beam or dipped beam functions. This can be done by means of an overlapping strip used for correct homogeneity, either at least 1° below the horizontal cut of the dipped beam (in particular the module can participate in or carry out the formation of the part of the dipped beam located above the level of the horizontal cut (in this case there is not necessarily an additional dipped module as such, but a simple flat cut module) or of a class E beam as defined in UNECE Regulation 123, version in force on the date of filing of this application.

[0014] Alternatively, the lighting function can be a high beam supplement function used to participate in a high beam in combination with a basic module, for example used for the low beam function.

[0015] According to another aspect, the present invention also relates to a module comprising a light source associated with an optical projection system according to the invention and which is configured to produce an output light beam, emitted by an output diopter of the output optical group, from light from at least one light source and entering directly into the optical projection system.

[0016] According to an unclaimed possibility, a vehicle is equipped with at least one module according to the present invention. Alternatively, a device composed of two modules spaced laterally at the front of the vehicle may be used. Another possibility is the use of two modules arranged in a single projector, that is, in a single projector body with a single closing lens. In this context, the two optical projection systems may be offset laterally, for example, by a distance corresponding to the spacing between two light sources of a module.

[0017] According to the invention, the input optical group consists of a lens provided with an aspheric input diopter or an aspheric output diopter. This fulfills the function of a field lens while allowing for specific correction of aberrations at the edges of the field.

[0018] In an alternative embodiment of the invention, the input optical group consists of two spherical lenses. This makes it possible to obtain a result equivalent to the previous case, with, admittedly, more lenses, but lenses that are easier to manufacture.

[0019] Optionally, the entrance diopter of the input optical group is convex.

[0020] Preferably, the types of glass used for at least one of the optical groups are different so as to compensate for chromatic aberration. In particular, Flint and Crown glass lenses can be alternated; this can be achieved by using doublets based on two lenses of each type of glass, thus creating achromatic doublets. Advantageously, Flint and Crown glass are alternated along the path of the light rays throughout the entire optical system.

[0021] According to one possibility, at least the output lens of the optical system (typically the fourth lens) is made of Crown glass.

[0022] In one embodiment, the module of the invention comprises a plurality of light sources, these sources being spaced apart from each other transversely to the optical axis of the optical projection system, with respect to which they are preferably symmetrical.

[0023] Following a non-limiting approach, the module is configured so that the maximum sharpness of the projected beam is not centered, and preferably is located between the midpoint and two-thirds of a horizontal projection sector at the optical axis. This corresponds to the fact that the radii of curvature are chosen so that the percussive response, measured as a mean ray (preferably using a root mean square of the RMS type) of the spot, has a minimum located in the off-axis field (between the midpoint and two-thirds of the field).

[0024] Advantageously, the following options can also be implemented alternatively or in any combination thereof: The entrance diopter of the input optical group is convex as seen from the source. The first lens is a meniscus lens whose concave diopter is turned away from the second lens. The entrance diopter of the second lens is convex, concave, or planar; thus, the second lens may be a biconvex lens, or a plano-convex lens whose planar diopter is turned towards the first lens, or a concave-convex lens whose concave diopter is turned towards the first lens, or the second lens may be a meniscus; preferably, the entrance diopter of the second lens has a larger radius of curvature than that of the exit diopter of the second lens;For example, the ratio of the radii of curvature can be greater than 5. The largest radius can be 163 mm and the smallest 30 mm. The third lens is a meniscus lens with its concavity facing the fourth lens. The fourth lens is a biconvex lens, or a plano-convex lens whose plane diopter is facing the third lens. The first lens is made of Flint glass. The second lens is made of Crown glass. The third lens is made of Flint glass. The fourth lens is made of Crown glass. The lenses of the intermediate optical group and the exit optical group all have spherical diopters; the term spherical is understood to also cover infinite radii of curvature, that is, lens surfaces of a flat shape; at least one lens is formed by the combination of two sublenses joined together, notably by gluing; the optical groups can follow one another, separated by an air gap;The input group is a Crown glass lens; alternatively, the input group comprises an upstream Flint glass lens followed directly by a downstream Crown glass lens; at least one light source is a pixelated light source, such as a monolithic LED chip; the light beam is projected directly onto the road; the light beam is configured to illuminate mostly or entirely above a horizontal cutoff line; the beam is applied to a high beam function to perform it completely or in addition to another beam, for example, a base beam below the horizon line; this function is possibly of the adaptive high beam type.

[0025] In a preferred embodiment, the module is configured to project to the front of a motor vehicle.

[0026] Other features and advantages of the present invention will be better understood with the aid of the exemplary description and drawings, among which: there figure 1 shows a schematic representation of a module of the invention, in an embodiment with two light sources; the figure 2 illustrates a first embodiment with a selection of lenses for the projection system; the figure 3 shows a variant of the embodiments of the figure 2 .

[0027] Unless specifically stated otherwise, technical features described in detail for a given embodiment may be combined with technical features described in the context of other embodiments described by way of example and not limitation.

[0028] In the characteristics described below, the terms relating to verticality, horizontality, and transverseity (or lateral direction), or their equivalents, refer to the position in which the lighting module is intended to be mounted in a vehicle. The terms "vertical" and "horizontal" are used in this description to designate directions, with "vertical" (corresponding to the height of the modules) being perpendicular to the horizontal plane, and "horizontal" being parallel to the horizontal plane. These directions are to be considered under the operating conditions of the device in a vehicle. The use of these terms does not imply that slight variations around the vertical and horizontal directions are excluded from the invention.For example, an inclination of + or - 10° relative to these directions is considered here as a minor variation around the two preferred directions. With respect to the horizontal plane, the inclination is generally between -5° and +4°, and laterally between -6° and +7.5°.

[0029] The optical system of the invention comprises a plurality of lenses. By convention, they are identified in the drawings with increasing reference numbers.

[0030] The module of the invention incorporates at least a first light source 1 enabling the generation of a segmented beam to be projected via the optical system 2.

[0031] The invention can contribute to a low beam function or, optionally, to a high beam function. The basic high beam function is to illuminate a wide area in front of the vehicle, as well as a considerable distance, typically around two hundred meters. This light beam, by its very nature, is located primarily above the horizon line. It may, for example, have a slightly upward optical axis of illumination. In particular, it can be used to generate a "high beam supplement" function, which forms a portion of a high beam complementary to that produced by a near beam. The high beam supplement aims to illuminate all or at least mostly above the horizon line, while the near beam (which may have the characteristics of a low beam) aims to illuminate all or at least mostly below the horizon line.

[0032] The device can also be used to create other lighting functions via or outside of those described previously.

[0033] There figure 1 shows a schematic representation of an example module with two light sources 1 and an optical projection system 2 comprising optical groups 3, 4, 5, the light rays passing through system 2 producing a beam 6 projected towards the front of the module. The optical axis 7 of the optical system is also shown schematically on the figure 1 .

[0034] As is known per se, the present invention can utilize light sources of the type light-emitting diodes, commonly known as LEDs. These may optionally be organic LED(s). In particular, these LEDs may be equipped with at least one chip using semiconductor technology and capable of emitting light. Furthermore, the term "light source" here refers to an assembly of at least one elementary source, such as an LED, capable of producing a flux that generates at least one light beam at the output of the module of the invention. In an advantageous configuration, the output face of the source has a rectangular cross-section, which is typical for LED chips.

[0035] Preferably, the light source comprises at least one monolithic array of light-emitting elements, also called a monolithic matrix. In a monolithic matrix, the light-emitting elements are grown from a common substrate and are electrically connected in such a way that they can be selectively activated, either individually or in subsets. The substrate may be predominantly made of a semiconductor material. The substrate may also include one or more other materials, for example, non-semiconductors. Thus, each light-emitting element or group of light-emitting elements can form a luminous pixel and emit light when its material or materials are supplied with electricity.The configuration of such a monolithic matrix allows for the arrangement of selectively activated pixels very close to one another, compared to conventional light-emitting diodes intended to be soldered onto printed circuit boards. The monolithic matrix as defined in the invention comprises electroluminescent elements whose principal elongation dimension, namely the height, is substantially perpendicular to a common substrate, this height being at most equal to one micrometer.

[0036] Advantageously, the monolithic matrix(s) capable of emitting light beams can be coupled to a control unit for the light emission of the pixelated source. The control unit can thus command (or, in other words, control) the generation and / or projection of a pixelated light beam by the lighting device. The control unit can be integrated into the lighting device. The control unit can be mounted on one or more of the matrices, the assembly thus forming a lighting module. The control unit may include a central processing unit coupled with memory on which a computer program is stored. This program contains instructions that allow the processor to perform steps that generate signals enabling the control of the light source. The control unit can thus, for example, individually control the light emission of each pixel of a matrix.In addition, the luminance obtained by the plurality of electroluminescent elements is at least 60Cd / mm 2<, preferably at least 80Cd / mm 2<.

[0037] The control unit can be an electronic device capable of controlling the electroluminescent elements. The control unit can be an integrated circuit. An integrated circuit, also called an electronic chip, is an electronic component that reproduces one or more electronic functions and can integrate several types of basic electronic components, for example, in a small volume (i.e., on a small board). This makes the circuit easy to implement. The integrated circuit can be, for example, an ASIC or an ASSP. An ASIC (acronym for "Application-Specific Integrated Circuit") is an integrated circuit developed for at least one specific application (i.e., for a customer). An ASIC is therefore a specialized integrated circuit (microelectronics). In general, it incorporates a large number of unique or customized functionalities.An ASSP (Application Specific Standard Product) is an integrated electronic circuit (microelectronics) that incorporates a large number of functionalities to meet the needs of a generally standardized application. An ASIC is designed for a more specific need than an ASSP. The monolithic matrices are powered via the electronic device, which is itself powered by means of, for example, at least one connector linking it to a power source. The power source can be internal or external to the device, according to the invention. The electronic device supplies power to the light source. The electronic device is thus capable of controlling the light source.

[0038] According to the invention, the light source preferably comprises at least one monolithic matrix whose electroluminescent elements protrude from a common substrate from which they respectively grew. Different arrangements of electroluminescent elements can meet this definition of a monolithic matrix, provided that the electroluminescent elements have one of their principal elongation dimensions substantially perpendicular to a common substrate and that the spacing between the pixels, formed by one or more electroluminescent elements electrically grouped together, is small compared to the spacings imposed in known arrangements of flat square chips soldered onto a printed circuit board.

[0039] In particular, the light source according to one aspect of the invention may comprise a plurality of electroluminescent elements distinct from the others and which are grown individually from the substrate, being electrically connected to be selectively activatable, where appropriate by subsets within which rods can be activated simultaneously.

[0040] According to an embodiment not shown, the monolithic matrix comprises a plurality of electroluminescent elements, of submillimeter dimensions, which are arranged protruding from a substrate to form rods with a hexagonal cross-section. The electroluminescent rods extend parallel to the optical axis of the light module when the light source is in position within the housing.

[0041] These electroluminescent rods are grouped, notably by electrical connections specific to each group, into a plurality of selectively activatable portions. The electroluminescent rods originate on one face of a substrate. Each electroluminescent rod, here formed using gallium nitride (GaN), extends perpendicularly, or substantially perpendicularly, from the substrate, which is here made of silicon. Other materials, such as silicon carbide, could be used without departing from the scope of the invention. By way of example, the electroluminescent rods could be made from an alloy of aluminum nitride and gallium nitride (AlGaN), or from an alloy of aluminum, indium, and gallium phosphides (AlInGaP).Each electroluminescent rod extends along an elongation axis defining its height, the base of each rod being arranged in a plane of the upper face of the substrate.

[0042] The electroluminescent rods of a single monolithic matrix advantageously have the same shape and dimensions. Each is delimited by an end face and a circumferential wall extending along the rod's elongation axis. When the electroluminescent rods are doped and polarized, the resulting light output from the semiconductor source is emitted primarily from the circumferential wall, although some light rays may also emerge from the end face. Consequently, each electroluminescent rod acts as a single LED, and the luminance of this source is enhanced both by the density of the electroluminescent rods present and by the size of the illuminating surface defined by the circumferential wall, which extends around the entire circumference and height of the rod.The height of a rod can be between 2 and 10 µm, preferably 8 µm; the largest dimension of the terminal face of a rod is less than 2 µm, preferably less than or equal to 1 µm.

[0043] It is understood that, during the formation of the electroluminescent rods, the height can be modified from one area of ​​the light source to another, thereby increasing the luminance of the corresponding area when the average height of the rods constituting it is increased. Thus, one group of electroluminescent rods can have a different height, or heights, than another group of electroluminescent rods, these two groups being part of the same semiconductor light source comprising electroluminescent rods of submillimeter dimensions. The shape of the electroluminescent rods can also vary from one monolithic matrix to another, particularly in terms of the rod cross-section and the shape of the terminal face. The rods generally have a cylindrical shape, and they can also have a polygonal cross-section, and more specifically a hexagonal shape.It is understood that it is important that light can be emitted through the circumferential wall, whether it has a polygonal or circular shape.

[0044] Furthermore, the terminal face may have a substantially flat shape and be perpendicular to the circumferential wall, so that it extends substantially parallel to the upper face of the substrate, or it may have a convex or pointed shape in its center, so as to multiply the directions of emission of the light coming out of this terminal face.

[0045] The electroluminescent rods are arranged in a two-dimensional matrix. This arrangement could be such that the rods are staggered. Generally, the rods are placed at regular intervals on the substrate, and the separation distance between two immediately adjacent electroluminescent rods in each dimension of the matrix must be at least 2 µm, preferably between 3 µm and 10 µm, so that the light emitted by the circumferential wall of each rod can escape from the electroluminescent rod matrix. Furthermore, it is expected that these separation distances, measured between two elongation axes of adjacent rods, will not exceed 100 µm.

[0046] According to another embodiment not shown, the monolithic matrix may comprise electroluminescent elements formed by epitaxially layered electroluminescent elements, specifically a first layer of n-doped GaN and a second layer of p-doped GaN, on a single substrate, for example silicon carbide, which is cut (by grinding and / or ablation) to form a plurality of pixels originating from the same substrate. This design results in a plurality of electroluminescent blocks, all originating from the same substrate and electrically connected so that they can be selectively activated from one another.

[0047] In an example of this alternative implementation, the monolithic matrix substrate can have a thickness between 100 µm and 800 µm, particularly 200 µm; each block can have a width of 50 µm and a width of 500 µm, preferably between 100 µm and 200 µm. In a variant, the length and width are equal. The height of each block is less than 500 µm, preferably less than 300 µm. Finally, the output surface of each block can be formed via the substrate on the side opposite the epitaxy. The separation distance between two pixels can be less than 1 µm, particularly less than 500 µm, and is preferably less than 200 µm.

[0048] Regarding monolithic chips with light-emitting blocks: The number of pixels can range from 250 to several thousand, with a typical value around one thousand pixels. Their overall shape is usually square, but can also be rectangular. The aspect ratio is generally between 1:1 and 1:5. The size of a single pixel (square in all known cases, possibly rectangular) is between 100 and 300 µm in the current state of the art.

[0049] According to another embodiment not shown, whether with electroluminescent rods extending from the same substrate, as described above, or with electroluminescent blocks obtained by cutting electroluminescent layers superimposed on the same substrate, the monolithic matrix may further comprise a layer of a polymer material in which the electroluminescent elements are at least partially embedded. This layer may extend over the entire surface of the substrate or only around a specific group of electroluminescent elements. The polymer material, which may be silicone-based, creates a protective layer that safeguards the electroluminescent elements without hindering the diffusion of light rays.Furthermore, wavelength conversion devices, such as phosphors, can be integrated into this polymer layer. These phosphors are capable of absorbing at least a portion of the light emitted by one of the elements and converting at least a portion of the absorbed excitation light into emitted light with a different wavelength. The phosphors can be either embedded within the polymer material or placed on its surface. The light source may also include a reflective coating to deflect the light rays towards the output surfaces of the pixelated source.

[0050] Electroluminescent elements of submillimeter dimensions define a specific output surface in a plane substantially parallel to the substrate. It is understood that the shape of this output surface is defined according to the number and arrangement of the electroluminescent elements that compose it. Thus, a substantially rectangular shape of the emission surface can be defined, it being understood that this shape can vary and take on any form without departing from the scope of the invention.

[0051] In the implementation of the figure 1 , two sources 1 are used and they are spaced relative to the optical axis 7 of the optical system 2, of the light from each of the sources 1 entering simultaneously into the system 2 through its input diopter, into the input group 3.

[0052] Surprisingly, the combination of three lens groups in system 2 provides both a wide field projection and optical quality that meets the requirements for lighting functions, particularly high beam functions, and even more specifically, adaptive high beam functions requiring the ability to efficiently transition (i.e., over a small angular distance, notably smaller than the angular size of the image of three, or preferably two, contiguous elementary sources) from an illuminated area to a non-glaring dark area (i.e., with system radiant intensities in this area below 625 cd) within the overall beam, all while minimizing chromatic aberration. A description of each optical group follows. Preferably, the lenses used have a circular cross-section (perpendicular to the optical axis).They are preferably made of glass. A lens can, as such, be formed from several sub-lenses of the same material assembled, notably by gluing; for example, two plano-convex sub-lenses can be joined to form a biconvex lens.

[0053] The optical input group 3 can be formed from a single lens or, alternatively, from a pair of lenses.

[0054] The first case is represented at the figure 2 with a biconvex 31 aspheric lens. Preferably, the type of glass used is different for this lens and the lens following it; it could be a Crown glass lens. The use of an aspheric lens improves the impulse response of the system for directions near the edge of the illuminated field, with a progressive modification of the lens curvature, particularly at its exit diopter: moving towards the periphery of the lens, for example, one passes from a zone of principal radius of curvature to a zone dealing only with rays from the lateral field, with a different curvature, preferably less than the principal curvature; an intermediate zone between the two previous zones can be formed to deal with less extreme rays.In general, it should be noted that the exit diopter of lens 31 can exhibit variable curvature towards its periphery, and in particular a peripheral zone of decreasing curvature. This zone may cover less than 10% of the lens diameter. An equivalent result is obtained, alternatively, with an aspheric entrance diopter, for example, following the profile described above for the exit diopter.

[0055] An alternative realization of input group 3 emerges from the figure 3 with a two-lens configuration, this time with spherical lenses. In this example, a lens 32 comprising the system's input diopter has a convex face 321 and an opposite concave face 322. It is followed by a lens 33 with a planar input diopter 331 and a convex output diopter 332. As mentioned previously, it is advantageous for the two lenses to be made of different types of glass. For example, lens 32 could be made of Flint glass and lens 33 of Crown glass.

[0056] Returning to the method of implementation of the figure 2 The intermediate optical group 4, following the input optical group 3, consists of a first lens 41 and a second lens 42. It is understood that the input diopter 411 of lens 41 receives the rays from the input group 3. Diopters 412 and 421 are opposite each other, and diopter 422 emits the light rays towards the output group 5. Lens 41 is a meniscus lens with one face 411 forming the meniscus cavity and an opposite face 412 being convex, the whole being preferably spherical. Lens 42, in the case shown, is a concave-convex lens, the convex surface forming the output diopter 422. Diopter 421 can alternatively be convex, as is the case in the embodiment of the figure 3 As with the first group, it is advantageous to continue alternating the types of glass in this second group 4. The combination of lenses 41 and 42 is configured to form a Gaussian doublet.

[0057] In an embodiment not shown, the intermediate group 4 is a pair of lenses replacing lens 42; in particular, two concave-convex lenses can be used in succession, with the convexity of an upstream lens being followed by the concave face of the downstream lens. The concave faces may have an infinite radius of curvature, i.e., be planar.

[0058] The third group is the optical output group 5. The embodiments of figures 2 And 3illustrate identical arrangements for this group. In particular, it consists of a third lens 51 (following the second lens 42 described previously) and a fourth lens 52 following the third lens 51. Lens 51 is of the meniscus type with a convex entrance diopter 511 and a meniscus cavity forming the exit diopter 512. Lens 52 comprises an entrance diopter 521 of the convex or planar type and a convex exit diopter 522. This latter portion forms the output of the entire projection system 2. The combination of lenses 51 and 52 is configured to form a Fraunhofer doublet.

[0059] Examples of glass type and lens geometry corresponding to the implementation of the figure 3 , without it being absolutely necessary to use these examples in strict combination (the reference to the type of materials is given according to the SCHOTT ® classification; the diameter of the largest lenses is preferably around 40 mm): Lens 32: ∘ Flint glass N-LAF2 ∘ Surface 321: spherically convex with a radius of convexity of 40 mm ∘ Surface 322: spherically meniscus with a radius of convexity of 21.254 mm Lens 33: ∘ Crown glass, type N-LAK10 ∘ Surface 331: flat ∘ Surface 332: spherically convex with a radius of convexity of 16.597 mm Lens 41: ∘ Flint glass, type N-SF6 ∘ Surface 411: spherically meniscus with a radius of convexity of 14.398 mm ∘ Surface 412: spherically convex with a radius of convexity of 25.332 mm Lens 42: ∘ Crown glass, type N-LAK10 ∘ Surface 421: spherically convex with a radius of convexity at 163.091 mm ∘ face 422 convex spherical with a radius of convexity of 30.557 mm lens 51: ∘ Flint glass type N-SF6 ∘ face 511 flat ∘ face 522 concave spherical with a radius of concavity of 42.48 mm lens 52: ∘ Crown glass type N-LAK10 ∘ face 521 flat ∘ face 522 convex spherical with a radius of convexity of 31.645 mm The optical system according to this example has an aperture number N=0.75, also noted f / 0.75 or 1:0.75, and its footprint along the optical axis is less than 55 mm.

[0060] The invention is not limited to the embodiments described but to the scope of the attached claims. REFERENCES

[0061] 1. Light source 11. Emitting face 2. Optical projection device 3. Input optical group 31. Aspheric lens 311. Input diopter 312. Output diopter 32. Upstream lens 321. Input diopter 322. Output diopter 33. Downstream lens 331. Input diopter 332. Output diopter 4. Intermediate optical group 41. First lens 411. Input diopter 412. Output diopter 42. Second lens 421. Input diopter 422. Output diopter 5. Output optical group 51. Third lens 511. Input diopter 512. Output diopter 52. Fourth lens 521. Input diopter 522. Output diopter 6. Output light beam 7. Optical axis

Claims

1. Optical projection system (2) of a vehicle lighting module, characterized in that it consists of: - an input optical group (3) comprising at least one lens, capable of receiving light rays from a light source and making them converge, said input optical group (3) consists either of a lens (31) provided with an aspherical input diopter (311) or an aspherical output diopter (312) or of two spherical lenses (32,33); - an intermediate optical group (4) which consists of a first meniscus-type lens (41), directly receiving light rays from the input optical group (3), and a second lens (42) having a convex output diopter (422), the meniscus cavity of the first lens (41) being oriented away from the second lens (42); - an output optical group (5) which consists of a third meniscus-type lens (51), directly receiving light rays from the intermediate optical group (4), and a fourth biconvex or plano-convex lens (52) whose plane diopter is turned toward the third lens (51), the meniscus cavity of the third lens (51) being oriented toward the fourth lens (52).

2. Optical projection system (2) according to one of the preceding claims, in which the input diopter (311) of the input optical group (3) is convex.

3. Optical projection system (2) according to one of the preceding claims, in which the input diopter of the second lens (42) is convex, concave or plane, or in which the second lens (42) is a meniscus.

4. Optical projection system according to one of the preceding claims, in which the input diopter of the second lens (42) has a radius of curvature greater than that of the output diopter (422) of the second lens (42).

5. Optical projection system (2) according to one of the preceding claims, in which the first lens (41) is made of Flint glass.

6. Optical projection system (2) according to one of the preceding claims, in which the second lens (42) is made of Crown glass.

7. Optical projection system (2) according to one of the preceding claims, in which the third lens (51) is made of Flint glass.

8. Optical projection system (2) according to one of the preceding claims, in which the fourth lens (52) is made of Crown glass.

9. Optical projection system (2) according to one of the preceding claims, in which the lenses of the intermediate optical group (4) and the output optical group (5) all have spherical diopters.

10. Automotive lighting module comprising a light source (1) and an optical projection system (2) according to one of the preceding claims and which is configured to produce an output light beam (6), emitted by an output diopter (512) of the output optical group (5), from light from the at least one light source (1) and entering directly into the optical projection system (2).

11. Module according to the preceding claim, comprising at least one other light source (1) associated with the optical projection system (2) to produce the output light beam (6).

12. Module according to the preceding claim, in which the light sources (1) are symmetrically spaced around an optical axis (7) of the optical projection system (2).

13. Module according to one of claims 10 to 12, configured so that the maximum sharpness of the projected beam is located between the middle and two-thirds of a horizontal projection angular sector at the level of the optical axis.