Light emitting module

Abstract

The invention relates to a light module with beam scanning, in particular for motor vehicles, comprising: a light source (10) configured to generate a first light beam with a fast axis and a slow axis; a wavelength conversion element (7) comprising a conversion surface; a focusing system allowing the generation of a scanning light beam focused on the conversion surface. The focusing system comprises a collimating lens (1) at the output of the light source (10) and three refractive interfaces (21, 31, 41), one of which is dedicated to beam adjustment along the fast axis and the other two are dedicated to beam adjustment along the slow axis.

Description

Technical Field

[0001] The invention relates to the field of lighting modules and lighting and / or signaling devices. The invention can be used particularly advantageously in the field of motor vehicles. Background Art

[0002] Motor vehicle headlamps are equipped with one or more light modules arranged in a housing enclosed by an outer lens in order to obtain one or more lighting and / or signaling light beams output from the headlamp. In simple terms, the light module of the housing comprises in particular a light source emitting a light beam, an optical system comprising one or more lenses, and in some cases optical elements (e.g. reflectors) for directing the light generated by the light source to form a light beam output from the optical module. The same is true for taillights.

[0003] As regards the light source, laser diodes may advantageously be used instead of light emitting diodes to generate the light beams used to form the output illumination and / or signaling light beams.

[0004] However, the color of conventional laser beams does not correspond to the prescribed color of such lamps. Therefore, the lighting module comprises a wavelength conversion element having a conversion surface. The conversion element receives the light beam of the laser source and re-emits it (e.g. in the form of white light) towards the projection optical system. Therefore, the laser beam is not used directly to form an illumination and / or signaling beam, but is first projected onto a photoluminescent wavelength conversion element, e.g. of the phosphorescent and / or fluorescent type.

[0005] In order to illuminate a larger area of ​​the conversion element with the beam of the laser source, a scanning device is required. The beam is scanned from one edge of the area of ​​the conversion element to the other edge and preferably at a sufficiently high frequency that the human eye does not perceive the movement but sees the illumination beam generated by the light-emitting module as a continuous illumination. The scanning amplitude defines the movement of the beam in space and thus the size of the illuminated area on the conversion element.

[0006] Known scanning devices are, for example, MEMS (MEMS stands for Micro-Electro-Mechanical Systems) comprising one or more micromirrors that reflect the laser beam onto the area. For example, these micromirrors are driven to perform at least one rotational movement about an axis so that the area is scanned in a first direction. Scanning in two directions is optionally possible by a second micromirror, or by another rotational movement of the first micromirror about a second axis perpendicular to the first axis.

[0007] The dimensions of these elements constrain the arrangement of the elements in the light module. Specifically, the distance between the scanning device and the conversion element defines the size of the area scanned by the light beam, given that the scanning amplitude depends on the configuration of the scanning device. It is also required to obtain a specific size of the intersection point of the laser beam and the conversion element, which is called the target or "spot". Therefore, it is the spot that is scanned over the area of ​​the conversion element.

[0008] Furthermore, for reasons of efficiency, it is desirable to illuminate the surface of the micromirror substantially completely (especially so that the light beam is not concentrated on too small an area of ​​the micromirror), while ensuring that the light beam does not extend beyond the edge of the micromirror, which would cause energy loss and burn other components of the scanning device. Ideally, the light spot contacts the edge of the reflector when it reaches its maximum size. Therefore, the light beam of the light source must be calibrated so that its width is adapted to the size of the micromirror. For example, there are scanning devices that have micromirrors with rounded surfaces, or other micromirrors that have elongated cross-sections (e.g., 1 mm by 1.2 mm). Therefore, it is necessary to obtain a beam size that matches these different sizes through an optical device.

[0009] Furthermore, a light source, such as a laser diode, has a fast axis and a slow axis. The beam divergence is stronger along a first axis, called the "fast" axis, than along a second axis, called the "slow" axis. In other words, the behavior of a laser beam in the near field and in the far field is different in these two directions. Furthermore, the dimensions of the exit surface of the light source parallel to the slow axis are different from (larger than) the dimensions of the exit surface of the light source parallel to the fast axis. Thus, the beam generated by a laser source is wider in the direction of the slow axis than in the direction of the fast axis when close to the light source, and is smaller in the direction of the slow axis than in the direction of the fast axis when farther away from the light source.

[0010] This difference in divergence speed places an additional constraint on the definition of the shape of the light beam to be generated.

[0011] All these constraints have to be met, which means in the prior art using lenses of complex shapes, typically aspherical or ascylindrical surfaces, and bulky focusing systems.

[0012] It is therefore an object of the present invention to provide an improved module for projecting a scanning light beam, thereby ensuring that the light beam used for scanning has an appropriate size at the scanning device and the conversion element.

[0013] Other objects, features and advantages of the present invention will become apparent by reviewing the following description and accompanying drawings. It should be understood that other advantages may be combined. Summary of the invention

[0014] According to one embodiment, the invention provides a lighting module in which a light beam is scanned, said module being particularly intended for a motor vehicle and comprising:

[0015] - a light source configured to generate a first light beam having a fast axis and a slow axis;

[0016] - a wavelength converting element comprising a converting surface;

[0017] - a focusing system arranged to generate a light beam, the focusing system comprising an optical device and a scanning device, the optical device being configured to generate a second light beam from a first light beam, the scanning device generating a light beam by reflecting the second light beam, and the optical device and the scanning device being arranged so that the light beam scans a conversion surface, the focusing system being configured so that the light beam is focused on the conversion surface.

[0018] Advantageously, the module is such that the optical device comprises:

[0019] - a collimating lens configured to generate a collimated light beam from the first light beam;

[0020] - Three non-planar cylindrical refractive interfaces, the non-planar cylindrical refractive interfaces are placed after the collimating lens on the path of the light from the light source and include: a first refractive interface, the first refractive interface is configured to produce beam convergence only along the fast axis, so that along the fast axis, the size of the second light beam is suitable for the size of the scanning device, a second refractive interface, the second refractive interface is configured to produce beam divergence only along the slow axis, and a third refractive interface, the third refractive interface is placed after the second refractive interface on the path of the light from the light source, the third refractive interface is configured to produce beam convergence only along the slow axis, the second cylindrical refractive interface and the third cylindrical refractive interface are configured so that along the slow axis, the size of the second light beam is suitable for the size of the scanning device.

[0021] In this way, based on the light beam output from the collimating lens, the light beam to be focused on the conversion surface is formed in an improved manner using a refractive surface that is easy to design and manufacture. The collimating lens can be a lens integrated into the light source. In particular, a light source in the form of a laser diode can be used, in which there is an aspherical collimating lens at its exit.

[0022] Advantageously, the second cylindrical refractive interface and the third cylindrical refractive interface are configured so that along the slow axis, the size of the image of the light source when it reaches the conversion device is smaller than a given size. In this way, two parameters are adjusted along the slow axis: the size of the light beam is suitable for the scanning device, and the magnification (because the size of the light source is not negligible in this direction), so that when the light spot reaches the conversion element, the size of the light spot is not too large (to allow the projection beam to have good precision).

[0023] It should be noted that in a module such as the one according to the invention, it is crucial to define the light beam under strict constraints. In particular, the surface of the scanning device must be covered as widely as possible in order to distribute the heat as best as possible, but it is avoided that the light beam extends beyond this surface so as not to damage peripheral components such as the mirror drive components (especially magnets and universal joints). For this purpose, the size of the light beam must be set specifically by the focusing system. At the same time, the light beam received by the conversion surface must be focused as best as possible in order to increase the precision of the useful light beam emitted (especially towards the front or rear of the vehicle). According to the invention, these constraints can be met in a simple and as compact as possible manner.

[0024] Optionally, the first refractive interface is placed between the second and third refractive interfaces on the light path from the light source. By nesting in this way, the refractive interfaces can be arranged compactly despite their different functions; the two refractive interfaces for the slow axis can be sufficiently far apart to achieve sufficient divergence using the second refractive interface and then insert the first refractive interface.

[0025] Advantageously, the three cylindrical refractive interfaces are carried by three different lenses. The lenses may be plano-concave or plano-convex lenses of simple geometry with cylindrical properties.

[0026] Preferably, the planar refractive interface is directed downstream on the light path such that the three cylindrical refractive interfaces face the light source.

[0027] Another aspect of the invention relates to a lighting device, in particular for lighting and / or signaling a motor vehicle, comprising at least one module according to the invention. This device may comprise a housing which accommodates the module and is enclosed by an outer lens through which an output light beam is projected from the module and possibly via projection optics towards a road.

[0028] A further aspect of the invention is a motor vehicle equipped with at least one module and / or at least one device according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The objects, purposes, features and advantages of the present invention will become more apparent through the detailed description of an embodiment of the present invention, which is illustrated by the following accompanying drawings, in which:

[0030] [ Figure 1 ] shows a spatial representation of a module according to the invention, wherein the path followed by light from the light source to the conversion surface is illustrated.

[0031] [ Figure 2 ] is a planar representation of the module in a plane containing the optical axis of the light source and its fast axis.

[0032] [ Figure 3] shows the beam formation along the fast axis.

[0033] [ Figure 4 ] is a planar representation of the module in a plane containing the optical axis of the light source and its slow axis.

[0034] [ Figure 5 ] shows the beam formation along the slow axis.

[0035] The accompanying drawings are given by way of example and do not limit the present invention. They are intended to facilitate understanding of the present invention and are not necessarily drawn to scale for actual applications. In particular, for simplicity, Figures 2 to 5 shows a planar representation, whereas in reality the scanning device changes the direction of the scanning beam sent towards the conversion surface, as Figure 1 shown. DETAILED DESCRIPTION

[0036] Before starting to discuss the embodiments of the present invention in detail, optional features that may be optionally used in combination with or alternatively used with the embodiments of the present invention will be described below:

[0037] - the first refractive interface 31 is placed between the second refractive interface 21 and the third refractive interface 41 on the path of the light coming from the light source 10;

[0038] - The collimating lens 1 is an aspherical lens;

[0039] - the collimating lens is formed integrally with the light source;

[0040] - the light source 10 is a laser diode;

[0041] - the most upstream refractive interface of the three cylindrical refractive interfaces 21, 31, 41 on the path of the light from the light source 10 is placed directly after the collimating lens 1; "directly after" means that no other optical elements are placed between the light source 10 and the collimating lens 1;

[0042] - three cylindrical refractive interfaces 21, 31, 41 are carried by three different lenses 2, 3, 4;

[0043] - three cylindrical refractive interfaces 21, 31, 41 are formed by the incident refractive interfaces of the three lenses 2, 3, 4 respectively;

[0044] - Each of the three lenses 2, 3, 4 has a planar exit refractive interface;

[0045] - the three lenses 2, 3, 4 are directly adjacent to each other; "directly adjacent" means that no other optical elements are placed between them;

[0046] the second light source and the second optical device are configured to generate an additional second light beam, and the module comprises an element for combining the second light beam 53 and the additional second light beam upstream of the scanning device 6;

[0047] - The combining element comprises an optical unit 5 for unifying the light beam.

[0048] - the first refractive interface 31 is arranged so that, along the slow axis, the size of the second beam 53 is smaller than or equal to the size of the scanning surface; it may be, for example, smaller than 10%, or even smaller than 5%;

[0049] - the second cylindrical refractive interface 21 and the third cylindrical refractive interface 41 are configured so that along the fast axis, the size of the second light beam 53 is smaller than or equal to the size of the scanning surface; it may be, for example, smaller than 10%, or even smaller than 5%;

[0050] the scanning device 6 comprises a surface for reflecting the second light beam 53 to produce a change in direction so as to form a light beam to be irradiated onto the conversion surface; the scanning device 6 is advantageously equipped with at least one movable micromirror configured to scan the conversion surface with the light beam at least in a first direction;

[0051] - The three cylindrical refractive interfaces 21, 31, 41 have arc-shaped cross sections;

[0052] - the conversion element 7 comprises a phosphorescent material;

[0053] The generated light beam is a laser beam, preferably produced by a laser diode.

[0054] The lighting module can be used, in particular, for lighting, taillights or headlights and / or interior lighting of a motor vehicle.

[0055] exist Figure 1 In the embodiment, the light module comprises a light source 10, preferably a monochromatic light source, such as coherent light, which can generate a first light beam having a propagation axis indicated by a dotted line starting from the light source 10, and a slow axis and a fast axis oriented in directions perpendicular to each other and perpendicular to the propagation axis. The light source is also advantageously configured to emit a polarized light beam. The light source 10 is preferably a laser diode, the light waves of the laser beam generated by the laser diode having substantially the same wavelength (e.g. 448 nm) to obtain a blue color.

[0056] The light module further comprises a wavelength conversion element 7, which advantageously has a photoluminescent conversion surface, which is configured to convert the wavelength (or wavelength interval) of the light beam it receives, for example by spreading the light wave distribution to wavelengths corresponding to different colors. Thus, by means of the conversion element 7, a light beam 72 is obtained from the initial light beam 63, which light beam 72 is re-emitted by the conversion element in another color spectrum distribution, in particular another color (for example white). According to another possibility, the light beam does not pass through the conversion element 7, and the conversion material is instead arranged on a reflector so that the converted light and the unconverted part of the incident light are reflected toward the projection optical device (in particular, in the taillight, even directly toward the exit outer lens). The conversion element 7 further comprises a conversion material and a reflector. The white light beam is used, for example, as an illumination beam in a motor vehicle lighting device. Therefore, a white light beam can be obtained by additively synthesizing a portion of the light emitted by the light source 10 and a portion of the light converted by the conversion element 7. Preferably, the luminescent material used is selected from the following compounds: Y 3 A 15 O 12 :Ce 3+ (YAG), (Sr,Ba) 2 SiO 4 :Eu 2+ , Ca x (Si,Al) 12 (O,N) 16 :Eu 2+ .

[0057] The light module further comprises a scanning device 6 so that the surface of the conversion element 7 is scanned by the light beam 63, which causes the light beam 53 to be scanned. The scanning device 6 is in particular a MEMS (MEMS stands for Micro-Electro-Mechanical System) comprising at least one micromirror. The micromirror is placed so as to interfere with the light beam from the light source 10. The micromirror reflects the light beam 53 (also referred to herein as the second light beam) towards the conversion surface of the conversion element 7. The micromirror is preferably driven to perform a rotational movement around an axis, which causes the surface of the conversion element 7 to be scanned. The light beam 53 advantageously scans the entire selected area on the conversion surface at a sufficiently high frequency, for example at least 200 Hz, or even at least 400 Hz, or even at least 700 Hz, that the human eye does not perceive the movement, but sees that the illumination due to the illumination beam generated by the conversion element 7 is continuous. The light module may comprise a protective housing for protecting the components, the housing comprising a transparent panel or a translucent panel, for example made of glass, so that the final light beam 72 is emitted.

[0058] The lighting module further comprises a focusing system placed between the light source 10 and the scanning device 6 to focus the light beam on the scanning device 6 so as to cover a large part of the micromirror while avoiding extending beyond its surface and in order to obtain the desired focus on the conversion surface of the conversion element 7 .

[0059] like Figure 1 As shown in the schematic representation of , the focusing system comprises a collimating lens 1 downstream of the light source 10 and preferably directly after the light source. This lens is used to produce a collimated light beam in the direction of the rest of the focusing system. The collimating function can be performed by the exit refractive interface 12 of the lens 1, in particular by the spherical shape of the refractive interface 1. Preferably, the lens 1 is formed integrally with the light source 10; in particular, some laser diodes include an optical focusing system directly connected thereto, such as The diode is manufactured by the company and carries the reference number NUB 805. The laser diode in question produces a diverging beam polarized linearly in the direction of the slow axis, and an associated collimating lens extracts therefrom a resultant beam having an elliptical base cylinder.

[0060] The composite beam is composed of Figure 1 The light beam 13 is denoted by the reference numeral 13 in the figure. Due to the difference in divergence of the light source 10 along its slow axis and along its fast axis, the final shape of the light beam 13 is a cylinder whose carrier corresponds to the main propagation axis (optical axis of the light source) and whose generatrix has an elongated shape, typically an ellipse, with the major axis of the ellipse oriented along the fast axis.

[0061] On the path of the light from the light source 10, the lens 1 is followed by three lenses 2, 3, 4, generating beams 23, 33, 43 respectively. These lenses 1, 2, 3, 4 are advantageously coaxial. This is a preferred, non-limiting way of arranging the three refractive interfaces, which, according to the invention, are used to match the focusing form of the beams with the constraints associated with the shape of the beams output by the light source (of the slow axis and the fast axis) to define the spot on the surface of the scanning device 6 and to achieve focusing on the conversion surface. Two refractive interfaces, indicated by reference numerals 21 and 41, are used here to change the beam only along the slow axis, and another refractive interface 31 is used to change the beam only along the fast axis.

[0062] In the case where each of the three refractive interfaces is carried by a separate lens, another refractive interface of these lenses is advantageously of planar shape. In the case where the refractive interfaces 21, 31, 41 themselves can be of simple geometric shape (typically a cylindrical shape with a circular arc cross section), it is therefore possible to use lenses 2, 3, 4 of simple design, typically plano-concave lenses or plano-convex lenses. Advantageously, the three refractive interfaces 21, 31, 41 are oriented to face the light source 10. In Figure 1 In the case of , the other refractive interfaces 22 , 32 , 42 of the lenses (these interfaces are planar) are oriented facing the scanning device 6 .

[0063] The functions and designs of the three refractive interfaces 21, 31, and 41 are described in detail below.

[0064] Figure 2 and Figure 3 A planar representation of the sequence of elements of the module of the invention is shown in a plane including the optical axis of the focusing system and the fast axis of the light source 10. The light source is shown as a point, which is very close to the reality along the fast axis. The divergence cone of the light beam emitted by the light source 10 is represented by Figure 3 The angle θ shown ⊥ Limited. Figure 2 , a cross section of lenses 1, 2, 3, 4 is given in the plane in question. However, it should be noted that in this plane, only the refractive interfaces 12 and 31 are not optically neutral.

[0065] Figure 3 The transformation of the light beam coming from the light source 10 in the plane in question is shown, considering for simplicity only the collimating lens 1 and the lens 3 carrying the dioptric interface 31 (this dioptric interface is also called the first dioptric interface in this description). In the following calculations for defining the optical element, the lens 2 has no influence here (planar plate with parallel faces in the calculation plane, where the collimated light beam is incident at right angles). The lens 4 and the combiner 5 also act as plates with plane faces and parallel in the calculation plane and have an effect equivalent to a corresponding increase in the "optical thickness" of the lens 3. Therefore, in the simplified thin lens calculation, they have no influence, but they must be taken into account in the calculation of the real lens. On the contrary, when the system is actually installed, the lens has a certain thickness, which must be advantageously taken into account. As can be seen above, the collimating lens 1 allows the divergent light beam output from the light source 10 to be collimated. The light source 10 is separated from the lens 1 by the focal length f a The collimated light beam 13 then impinges on the lens 3 and, through the dioptric interface 31 , is converged in the direction of the reflective surface of the scanning device 6 . Typically, this convergence is caused by the convex shape of the dioptric interface 31 .

[0066] The appropriate distance between the conversion element 7 and the lens 3 can be determined via geometric construction. Specifically, certain parameters of the module are usually predefined. For example, the parameter θ ⊥ and f aIn this case, it can be set in particular by the manufacturer of the laser diode with collimating lens. In addition, the distance D separating the scanning device 6 from the conversion element 7 can also be given; this distance depends on the area of ​​the conversion element that is desired to be scanned and on the maximum deflection angle of the scanning device: D tends to be chosen to be as small as possible in order to reduce the size of the device while still allowing the desired area to be scanned (and at the same time avoiding shadowing of the projection optics that may be located downstream of the device in the case where the conversion device operates in reflection). Finally, the size of the useful reflection surface of the scanning device in this plane (i.e. along the fast axis) is also determined by data from the manufacturer of this type of device. Symbol R mems Used to denote half of this dimension along the fast axis. In general, in the projection in a plane perpendicular to the propagation axis of the beam illuminating the mirror, the available width will be smaller than the dimension of the mirror in this direction in the case of reduced rotation of the mirror; the value of Rmems will then be set by the total half-width of the mirror and the maximum angle of rotation of the mirror (being the product of the half-width of the mirror by the cosine of the maximum angle of rotation from a rest position perpendicular to the axis of the beam to be reflected). The lens 3 is located at the intersection of the beam 13 and the convergent beam 53, which advantageously passes through the edge of the reflective surface of the scanning device 6 (without extending beyond this edge) and is focused on the conversion surface of the conversion element 7.

[0067] Then, the focal length f of the cylindrical lens 3 which separates the lens 3 from the surface of the conversion element 7 can be given by c :

[0068] [Formula 1]

[0069]

[0070] Regarding changing focus along the slow axis, Figure 4 and Figure 5 Shown with the Figure 2 and Figure 3 Exemplary embodiments equivalent to those described for the fast axis.

[0071] Figure 4 It is shown that, in the plane defined by the optical axis of the focusing system and by the slow axis, lens 3 is optically neutral, while the refractive interfaces 12 of lens 1, 21 of lens 2 and 41 of lens 4 successively modify the beam. For calculation purposes, lenses 1 and 3 are considered here to have no influence along this axis, equivalent to lens 2 in the other direction; therefore, in the simplified thin-sheet calculations, these elements have no influence, but they must be taken into account when calculating real lenses. On the contrary, when the system is actually installed, the lenses have a certain thickness, which must be advantageously taken into account. Lens 1 is based on the output of the light source 10 and corresponds to Figure 5 The cone angle θ shown in / / The divergent beam produces the collimation described above. In the plane in question, corresponding to the slow axis of the laser diode, the collimated beam has a smaller width. As above, fa represents the distance between the refractive interface 12 of the lens 1 and the light source 10. In this orientation, the collimated beam has a smaller width than the reference beam. Figures 2 to 3 Unlike the previous planes described, the initial object has a non-negligible size. Therefore, according to a preferred embodiment of the invention, along the slow axis, the magnification of the optics must be taken into account, since the light source is more elongated along this axis. Therefore, in addition to the use of a refractive interface 41 (here carried by the lens 4) with a converging effect in the direction of the scanning device 6, a refractive interface 21 (here carried by the lens 2) with a divergent effect is used, which serves to increase the cross-sectional area of ​​the light beam 33 impinging on the lens 4 in the plane of the figure, so that the intersection of the cone starting at the spot on the conversion device and passing through the edge of the scanning device in the plane of the figure with the cone starting at the lens 2 is located upstream of the scanning device and the optional combiner, the intersection being determined by the position of the lens 4. Advantageously, considering that the light beam impinging on the scanning device must not extend beyond the scanning device while remaining as wide as possible, it should be remembered that the angular deflection of the reflecting surface of the scanning device also means that the size of the spot of the light beam on the scanning device is reduced (for this purpose, the cosine of the deflection angle is taken into account).

[0072] Therefore, in Figure 4 and Figure 5 In the plane discussed in , a lens is used to change the shape of the light beam. Preferably, as Figure 4 As shown, the lens 3 discussed above with respect to its action along the fast axis is inserted between the two lenses 2 and 4 for the slow axis.

[0073] It should be noted that the use of three different lenses enables the use of an inexpensive and geometrically simple optical device. However, the invention does not exclude the use of a different number of lenses, in particular a single lens carrying two of the three refractive interfaces.

[0074] Figure 5 The geometric elements shown in demonstrate a method for determining the positions of lens 2 and lens 4. Some parameters as described above with respect to the fast axis, especially the following parameters, will typically be known / set by construction:

[0075] - Angle θ / / ;

[0076] - Distance f a ;

[0077] -R' mems ; This value preferably takes into account the deflection of the mirror and can be obtained along the fast axis (see R above mems Calculation of

[0078] - The height of the light source, h, is half the length of the light source along the slow axis;

[0079] - distance D;

[0080] - the height H of the image of the light source on the conversion surface is half the maximum size of the light spot;

[0081] - the distance Δ from the lens 4 to the conversion device for the light rays coinciding with the optical axis - the lens 4 is placed as close as possible to the scanning device (in order to minimize the overall volume of the device) while respecting the geometrical constraints imposed by the mechanical dimensions of the scanning system and allowing the provision of a second focusing branch coupled through the element 5;

[0082] In addition, using f d Denote the focal length of diverging lens 2, expressed in g 1 Denote the magnification of diverging lens 2, expressed in g 2 represents the magnification of the converging lens 4, d represents the distance between the lenses 2 and 4, and H represents 1 The height of the virtual image of the light source 10 passing through the diverging lens 2 is represented by f' c represents the focal length of the converging lens, which can be written as:

[0083] [Formula 2]

[0084]

[0085] [Formula 3]

[0086]

[0087] [Formula 4]

[0088]

[0089] [Formula 5]

[0090]

[0091] [Formula 6]

[0092]

[0093] The last two inequalities make it possible to choose d and fd from which f′c can be derived, which ultimately allows the characteristics and relative positioning of the thin lenses used to approximate lenses 2 and 3 to be determined.

[0094] The distance Δ is chosen, and the position of lens 2 and lens 4 is determined relative to the conversion device and the scanning device by calculating fc, and the position of lens 3 is also determined. The distance from the light source to the first lens is set by the recorded value of lens 1 (the distance between the light source and the entrance surface of the lens (the recorded value is equal to the focal length only when the lens is a thin lens)), and a single distance is not defined: the distance between lens 1 and lens 2. This distance can be chosen arbitrarily and is usually chosen to be as small as possible, taking into account the constraints of mechanical integration, especially the constraints of any focusing device set in the system.

[0095] According to a non-limiting embodiment, the module of the invention also comprises means allowing the light beams generated by two different light sources to be unified so as to form a stronger overall composite light beam in the direction of the scanning means 6. To this end, Figure 1 , Figure 2 and Figure 4 An exemplary embodiment schematically shown in FIG. 1 is to use a beam splitter for a backward polarized beam, i.e., to receive two different beams (beam 53, and another perpendicularly polarized beam preferably obtained by using the same devices as described above to generate beam 53, including a light source such as a laser diode with a collimating lens, and a focusing system including three refractive interfaces for changing the beam along the slow axis and the fast axis) and combine them into a single output. Figure 1 As an example, an additional light beam (not shown) will enter unit 5 laterally in a direction parallel to the slow axis. Unit 5 is typically a polarizing beam splitter consisting of two prism sections, each of which receives one of the two light beams and produces a combined output beam 53 in the direction of the scanning device by angularly steering one of the two input beams reflected at the interface of the prism. This principle (i.e., additional light beams and beam combination) can be reproduced many times using at least one other light source and one other system for generating one other additional light beam and one other unit for combining light beams. This can be done not by polarization, but by multiplexing different wavelengths (using dichroic mirrors). The beam splitter will pass the first wavelength and reflect the second wavelength.

[0096] The invention is not limited to the embodiments described above, but extends to all embodiments covered by the claims.

Claims

1. A lighting module with a scanning light beam (63), the module being for a motor vehicle and comprising: - a light source (10) configured to generate a first light beam (13) having a fast axis and a slow axis; - a wavelength conversion element (7) comprising a conversion surface; - a focusing system, the focusing system being arranged to generate the scanning beam (63), the focusing system comprising an optical device and a scanning device (6), the optical device being arranged to generate the second beam (53) from the first beam (13), the scanning device generating the scanning beam by reflecting the second beam (53) and being arranged such that the scanning beam (63) scans the conversion surface, the focusing system being arranged such that the scanning beam (63) is focused on the conversion surface, characterised in that the optical device comprises: - a collimating lens (1) configured to generate a collimated light beam from the first light beam (13); - three non-planar cylindrical refractive interfaces (21, 31, 41), which are placed after the collimating lens (1) on the path of the light from the light source and include: a first refractive interface (31), which is configured to produce a beam convergence only along the fast axis, so that along the fast axis, the size of the second light beam (53) is suitable for the size of the scanning device (6), a second refractive interface (21), which is configured to produce a beam divergence only along the slow axis, and a third refractive interface (41), which is placed after the second refractive interface (21) on the path of the light from the light source (10), and the third refractive interface (41) is configured to produce a beam convergence only along the slow axis, and the second and third refractive interfaces (21, 41) are configured so that along the slow axis, the size of the second light beam (53) is suitable for the size of the scanning device (6).

2. The module according to claim 1, wherein: The first refractive interface (31) is placed between the second refractive interface and the third refractive interface (21, 41) on the path of light from the light source (10).

3. The module according to claim 1, wherein: The collimating lens (1) is an aspherical lens.

4. The module according to claim 1, wherein: The collimating lens (1) is formed integrally with the light source (10).

5. The module according to claim 1, wherein: The light source (10) is a laser diode.

6. The module according to claim 1, wherein: The most upstream refractive interface of the three cylindrical refractive interfaces (21, 31, 41) along the path of the light from the light source (10) is placed directly after the collimating lens (1).

7. The module according to claim 1, wherein: The three cylindrical refractive interfaces (21, 31, 41) are carried by three different lenses (2, 3, 4).

8. The module according to claim 7, wherein: The three cylindrical refractive interfaces (21, 31, 41) are respectively formed by the incident refractive interfaces of the three lenses (2, 3, 4).

9. The module according to claim 7, wherein: Each of the three lenses has a planar exit refractive interface.

10. The module according to any one of claims 7 to 9, wherein: The three lenses (2, 3, 4) are directly adjacent to each other.

11. A module as claimed in claim 1, comprising a second light source and a second optical device configured to generate an additional second light beam, and an element for combining the second light beam (53) and the additional second light beam upstream of the scanning device (6).

12. The module of claim 11, wherein: The combining element comprises an optical unit (5) for unifying the light beam.

13. A lighting device for lighting and / or signaling of a motor vehicle, comprising at least one module as claimed in one of the preceding claims.

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