MOTOR VEHICLE LIGHTING MODULE WITH ONE ELEMENT FOR HOLDING THE PROJECTION LENS

Description

[0001] The present invention relates to a light module intended to be integrated into a lighting device for a motor vehicle.

[0002] It is well known that lighting devices heat up during use due to the heat emitted by the light sources within them. The temperature inside the lighting device rises, which can affect its internal components. For example, lenses housed within the lighting device often expand as the temperature increases when it is used to project a beam of light.

[0003] Thermal expansion of lenses can cause the focal point, or focal plane, associated with those lenses to shift. If the light source is designed to project a pattern, the shifted focal plane is no longer aligned with the pattern. The projected image therefore loses its sharpness. In other words, the quality of the projected image is compromised. This phenomenon is also called defocusing.

[0004] To address this problem, lenses are made from glass, a thermally stable material that withstands temperature increases well. However, these lenses are heavy and expensive. Furthermore, manufacturing glass lenses is complex. For use in automotive lighting, a portion of the glass lens is often made of plastic, which requires overmolding onto glass and complicates the manufacturing process.

[0005] Another proposed solution is to install the lens(es) in a support element that is highly resistant to high temperatures to prevent lens expansion. Specifically, the support element clamps around the perimeter of the lens or lens assembly. It thus remains rigid despite temperature increases and applies a constraint to the lens or lens assembly, preventing expansion. However, this localized constraint around the perimeter of the lenses shifts the deformation due to thermal expansion to a stress-free zone, particularly the central area where the optical surface of the lenses is located. Consequently, the optical surface is deformed more significantly than without a support element. This deformation is difficult to control and can have unpredictable effects on the focal plane location.

[0006] Known light modules are disclosed in documents DE 102017106654 A, US 2019 / 204528 A and JP 2021076621 A.

[0007] In light of the above, one objective of the invention is to design a light module, intended for mounting in a lighting device, which reduces, or even eliminates, the problem of defocusing due to the thermal expansion of optical elements. Such a light module also meets the requirements for manufacturing cost and weight while being simple to implement.

[0008] With this objective in mind, the invention proposes a lighting module comprising: a fixed base intended to serve as a support for a light source; a projection optic having a focal plane and arranged to project a beam of light from the light rays emitted by the light source; a holding element for the projection optic, said element comprising: a first support element; a second support element serving as a support for the projection optic.

[0009] According to the invention, the second support element is arranged to allow thermal expansion of the projection optics causing displacement of the focal plane in a first direction.

[0010] Furthermore, the first support element has a first coefficient of thermal expansion, while the second support element has a second coefficient of thermal expansion that differs from the first. Finally, the first support element is connected on one side to the fixed base and on the other side to the second support element in such a way that the second support element is displaced during the deformation of the first support element along a second direction opposite to the first direction.

[0011] Here, the fixed base serves as a reference point. It reacts little or not at all to temperature variations within the light module. For example, the fixed base could be made of an inert, temperature-insensitive material. The second support element carries the projection optics. For instance, the second support element includes a housing in which the projection optics are installed. Finally, the first support element acts as an intermediary between the fixed base and the second support element.

[0012] In the proposed light module, the projection optics are free to deform due to thermal expansion caused by the temperature increase inside the module. The displacement of the focal plane caused by this deformation is compensated by the holding mechanism.

[0013] Indeed, since the retaining element does not impede the expansion of the projection optics, the focal plane can move within a defined perimeter. However, the second element of the retaining element is designed to direct the movement of the focal plane in a specific direction. Simultaneously, the retaining element is also deformed, under the influence of temperature, so as to move the projection optics in the opposite direction to the movement of the focal plane.

[0014] Consequently, the focal plane remains close to or near its position before the temperature increase, despite its displacement caused by the thermal expansion of the projection optics. In other words, the defocusing phenomenon is compensated for in the proposed light module.

[0015] Thus, the projected image always remains sharp for good image quality, regardless of the operating time of the light module.

[0016] Furthermore, since the light module is capable of compensating for defocusing due to thermal expansion, it is possible to use a projection lens material that is sensitive to temperature variations but, conversely, inexpensive. For example, the projection lens can be made of polycarbonate (PC), polymethyl methacrylate (PMMA), or cycloolefin polymer (PCO), such as the Zeonex® brand. However, the proposed mounting bracket is perfectly suited to a glass projection lens.

[0017] In this document, the projection optics create a real, and possibly anamorphic, image of a part of the module, for example the source itself, or of an intermediate image of the source, at a distance (finite or infinite) much greater than the dimensions of the module (by a ratio of at least 30, preferably 100). This projection optics may consist of one or more reflectors, or one or more lenses, or one or more light guides, or a combination of these.

[0018] The light module according to the invention may optionally have one or more of the following characteristics: When the temperature varies from an initial value to a final value, the thermal expansion of the projection optics causes the focal plane to move a first distance, and the deformation of the first support element causes the second support element to move a second distance; furthermore, the first coefficient of thermal expansion and the second coefficient of thermal expansion are defined such that the first distance is approximately equal to the second distance; by "approximately equal" is meant that the second distance may be equal to or slightly less than the first distance; thus, in addition to the opposing displacements, the projection optics and the focal plane are displaced approximately by the same distance; the displacement of each between the projection optics and the focal plane is characterized by a direction and a magnitude as a vector;In the case where the distances are equal, the vector characterizing the displacement of the projection optics and the vector characterizing the displacement of the focal plane are two opposite vectors that cancel each other out; thus, the focal plane is maintained at a desired location in the light module; here, by "desired location," we mean the place where, when the focal plane is located there, the image projected by the light module has good sharpness and luminance; the first support element is in contact with the fixed base at a first contact zone and in contact with the second support element at a second contact zone located opposite the first contact zone; in other words, the first support element has a fixed end by its connection with the fixed base and a free end by its connection with the second support element;In this way, when the temperature in the light module varies, the structural deformation of the first support element occurs at the second contact zone, or the free end, of the latter; here, "structural deformation" means the modification of a dimension of the first support element consisting, for example, of an elongation or a shortening of the latter; moreover, the structure of the first support element is simple and easy to make while being effective in compensating for the displacement of the focal plane of the projection optics; the first contact zone between the first support element and the fixed base can include at least a portion which is located substantially at the same level as the first face of the slide; thus, the working length in thermal expansion of the first element is maximized;of course, other portions of the first contact area are not necessarily at the same level as the first face of the slide; the projection optic has a first side oriented towards the light source, the second support element supporting the projection optic at the level of the first side; the projection optic comprises a central area performing an optical function, and a peripheral area surrounding the central area, the second support element being arranged so as to at least partially follow the peripheral area; this allows a good grip on the projection optic by the second support element; the projection optic has a second side opposite the first side, the second support element comprising an elastically deformable member bearing against the second side of the projection optic;Thus, under normal conditions, the elastically deformable member ensures good support of the projection optics by the second support element; however, when the temperature increases, this member deforms, which makes it possible for the projection optics to expand; the second support element comprises two distinct parts; according to an example, the second projection element comprises a first part and a second part which fit into each other so as to form a housing space for the projection optics, one of the two parts supporting the projection optics at the level of a first side of the projection optics and the other part comprising the elastically deformable member bearing on the projection optics at the level of a second side opposite to the first side;For example, the first part and the second part are hollow cylinders designed to fit into one another so as to form a space for the projection optics; the first part is intended to support the projection optics at the first end located on the side of the fixed base, the second part is partially fitted into the first part; and the unfitted portion of the second part includes an edge folded inwards towards the space to form an elastically deformable member; the folded edge bears against the second end of the projection optics; alternatively, the second support element is made in one piece; as an example, the second support element comprises a hollow cylindrical body with an annular wall and a collar projecting radially from this wall; the collar is intended to bear against one end of the first support element;The collar can be secured to the first support element by means of a layer of adhesive interposed between these two elements; the first and second support elements are connected to each other by gluing or snap-fitting; for example, fixing by gluing consists of using an adhesive cross-linked by ultraviolet radiation; obviously, other means of fixing can be considered; the light module includes a slide positioned upstream of the projection optics according to the direction of propagation of the light rays in the light module, the slide having a first face bearing a pattern to be projected and oriented towards the projection optics, and the desired location of the focal plane being on said first face or in the vicinity of said first face;In this application, "in the vicinity of" means a focal plane location at a distance from the first face such that the ray from the light source emerges substantially parallel to the optical axis of the projection lens; this distance is, for example, equal to one-tenth of the focal length of the projection lens; thus, the focal plane is always located at and near the first face of the slide so as to ensure a sharp projection of the image; alternatively, in an example where the light module does not have a slide, the desired focal plane location is on the light source; thus, the projection lens projects the image of the light source; according to one embodiment, the fixed base also serves as a support for the slide; thus, the light source and the slide are correctly positioned relative to each other from the outset, which simplifies the setup;the second coefficient of thermal expansion is less than the first coefficient of thermal expansion; in this document, the coefficients of thermal expansion are the linear thermal expansion coefficients in Kelvins to the power of minus one (K⁻¹); according to an example, the first support element is made from a material whose coefficient of thermal expansion is between 90 x 10⁻⁶ K⁻¹ and 180 x 10⁶ K⁻¹, preferably between 100 x 10⁶ K⁻¹ and 150 x 10⁶ K⁻¹; the first support element is made from polyamide; the second support element is made from a material whose coefficient of thermal expansion is between 12 x 10 -6< K -1< and 30 x 10 6< K -1<, preferably between 15 x 10 -6< K -1< and 24 x 10 -6< K -1<; the second support element is made from a material chosen from aluminium and steel;The projection optics have a coefficient of thermal expansion greater than the coefficient of thermal expansion of the second support element; the projection optics comprise several lenses which are stacked one on top of the other; for example, the number of lenses may be between 2 and 6; optionally, the projection optics comprise four lenses; these four lenses may be made of the same material chosen from glass or plastic, or they may be a combination of glass and plastic lenses; the light module further comprises a light source and a collimator disposed downstream of the light source according to the direction of propagation of the light rays from the light source, the collimator comprising an upstream face disposed opposite the light source and a downstream face disposed opposite the slide;Thus, the light beam exiting the collimator is composed of parallel rays directed towards the projection optics; the collimator therefore limits the dispersion of the light rays emitted by the light source; when the light module is integrated into a lighting device, the fixed base is connected to a housing of this device;

[0019] The invention also relates to a motor vehicle lighting device comprising a lighting module according to the invention.

[0020] As an example, the lighting device provides an auxiliary function of illuminating the space located on either side of the vehicle.

[0021] In one embodiment, the lighting device comprises a housing. The fixed base is connected to the housing by suitable fastening means.

[0022] Other innovative features and advantages will become apparent from the following description, provided for illustrative purposes only and not as a limitation, with reference to the attached drawings, in which: [ Fig.1 ] represents a side view of a motor vehicle comprising a light module according to an embodiment of the invention; [ Fig.2 ] represents a cross-sectional view of the light module of the [ Fig.1 ] ; ] Fig.3 ] represents a detailed cross-sectional view of the light module of the [ Fig.1 ] ; ] Fig.4 ] represents an exploded view of the light module illustrated in the [ Fig.3 ]. Fig.5 ] represents a schematic illustration of the light module at ambient temperature T0 ( figure 5A ) and at a first temperature T1 higher than the ambient temperature ( figure 5B ).

[0023] With reference to these figures, in particular to the [ Fig.1 ], a motor vehicle 10 includes, on the left side shown, a front door 11 and a rear door 13. A lighting device comprising a light module 1 (not visible on the [ Fig.1 ]) is installed in a door sill 12 located under the front doors 11 and rear doors 13. In the illustrated example, the lighting device is located at the front end of the door sill 12 and is arranged to project onto the ground a field of illumination S which extends parallel to the main axis P of the vehicle 10 and to the rear of the vehicle 10. The projection axis forms an angle α with a horizontal axis.

[0024] The lighting device serves as a means of lateral lighting for the space located next to the front and rear entrance doors.

[0025] On the [ Fig.2 ], the light module 1 includes a light source 2, a projection optic 3 and a slide 5 arranged between the light source 2 and the projection optic 3.

[0026] Light source 2 is a light-emitting diode (LED). Other types of light sources are possible. Light source 2 may consist of one or more LEDs.

[0027] In the illustrated example, the projection optic 3 has a focal plane F and is composed of a plurality of lenses 30 which are stacked against each other. There are four lenses in this example.

[0028] Each of the lenses 30 comprises a central zone 311 with dioptric surfaces performing an optical function and a peripheral zone 312 surrounding the central zone 311. The dioptric surfaces are parameterized to project the rays from the light source 2 while limiting optical aberrations, such as distortion. The projection optics 3 are hereinafter referred to as the lens assembly 3.

[0029] The peripheral zone 312 is provided with engagement means intended to cooperate with complementary engagement means of the peripheral zone of the adjacent lens. By way of example, engagement means may include a groove or a rib.

[0030] Slide 5 is shown here as a transparent plate 53, which, for illustrative purposes, has a square cross-section. Slide 5 can be made of glass, for example borosilicate glass, or of plastic, for example polyethylene terephthalate (PET).

[0031] Slide 5 has a first face 51 and a second face 52. The slide is placed in the light module 1 so that the first face 51 is oriented towards the lens assembly 3 and the second face 52 is oriented towards the light source 2. The first face 51 is also called the downstream face and the second face 52 the upstream face. The terms "upstream" and "downstream" are defined according to the direction of light propagation in the light module 1.

[0032] THE figures 3 et 4 illustrate in more detail the light module 1 by showing additional elements of the light module 1, including a retaining element 4 and a fixed base 7.

[0033] In the illustrated example, the fixed base 7 serves as a support for the light source 2 and for the slide 5. Here, the fixed base 7 includes a base 20 on which the light source 2 is mounted. The base 20 can be a printed circuit board (also called PCB, the abbreviation of the Anglo-Saxon term: Printed circuit board).

[0034] The fixed base further includes a frame 50 carrying the slide 5 and a collimator 6 placed between the light source 2 and the slide 5. Here, the collimator 6 is an integral part of the frame 50. The collimator 6 comprises an upstream face 61 arranged opposite the light source 2 and a downstream face 62 arranged opposite the slide 5.

[0035] In this example, the frame 50 is attached to the base 20 by means of two fixing tabs 51 and two pins 52. Specifically, the fixing tabs 51 are abutted against a secondary face 22 of the base 20 while the pins 52 are engaged in the corresponding holes made in the base 20. In this way, the base 20 and the frame 50 form a block constituting the fixed base 7.

[0036] The projection optic 3 is connected to the fixed base 7 via the retaining member 4. Here, the retaining member 4 serves both as a lens support 30 and as a means of positioning the lenses relative to the slide 5.

[0037] According to the invention and as in the illustrated example, the retaining member 4 comprises a first support element 41 and a second support element 42.

[0038] The first support element 41 is the intermediate piece that connects the fixed base 7 to the second support element 42. Specifically, the first support element 41 is formed by a cylindrical sleeve interposed between the fixed base 7 and the second support element 42. This first element is also referred to as a barrel in the terminology of those skilled in the art. The first support element 41 includes engagement tabs 412 which are designed to be inserted into grooves 513 formed in the fixed base 7 to assemble these two elements.

[0039] Once assembled, the first support element 41 is in contact with the fixed base 7 at its first end 411 oriented towards the fixed base 7. The first end 411 is also called the first contact zone 411.

[0040] Here, the first contact zone 411 comprises several contact portions. Some of these are located at the same level as the first face 51 of the slide 5. Others are located at a higher level than the slide, notably the contact portions between the first support element 41 and the shoulder of the mounting tabs 51 of the frame 50. In other words, the connection between the first contact zone 411 and the first face 51 can be made at different levels.

[0041] In the illustrated example, the first support element 41 is connected to the second support element 42 at its second end 412, located opposite the first end 411. Here, the first support element 41 is in contact with the second support element 42 via a layer of adhesive that bonds the two elements together. Other means of connection can be considered. The adhesive bond between the first support element 41 and the second support element 42 allows for easy adjustment of the focal plane F of the lens assembly 3 relative to the slide 5.

[0042] Here, the second support element 42 comprises two separate parts that fit together to form a housing space for the lens assembly 3. The second support element 42 is also called the lens box.

[0043] Specifically, the first part 421 comprises a hollow cylindrical body open at both ends. However, the opening on one end is narrower than the other. The first end of the first part 421, the one facing the light source, has an inwardly folded edge to create an annular seat 423. This annular seat 423 has a shape complementary to the shape of the peripheral area 311 of the lens 30, which is in direct contact with it. In this way, the annular seat 423 fits perfectly against the peripheral area 311 to ensure a secure connection between the first part 421 and the lens 30. The annular seat 423 defines a first opening 425 whose diameter corresponds to the diameter of the central area 312 of the lenses 30.

[0044] The second side of the first part 421, opposite the first side, includes a collar 424 that rests on the second end 412 of the first support element 41 and is fixed thereto by suitable means, for example, by an ultraviolet-curing adhesive, a thermal adhesive, or a combination of these two types of adhesives. The collar 424 defines a second opening 426 having a diameter larger than the diameter of the first opening 425. The second opening 426 is provided to be sufficiently large to receive the second part 422 of the second support element 42.

[0045] Here, the second part 422 also includes a hollow, through-cylindrical body. The second part 422 is partially fitted into the first part 421. The free end, that is, the unfitted end, of the second part 422 includes an edge 428 folded inwards and bearing against a diaphragm 33. The latter is part of the lens assembly 3 and includes an aperture that defines the optical surface of the lens assembly 3.

[0046] The second part 422 is designed so that the folded edge 428 exhibits elastic deformation behavior, meaning that the edge 428 tends to return to its initial position when deformed. Here, the second part 422 has a sufficiently small thickness to give the edge 428 this elastic behavior. The edge 428 as shown in the [ Fig.3 ] is in its initial position in which it rests on the diaphragm 33. This support is added to the contact of the annular seat 423 with the lens assembly 3 on the other side to tighten this assembly 3 by eliminating the play between the lenses 30.

[0047] The second part 422, thus designed, is also called the elastically deformable element. Furthermore, the elastic deformation of the edge 428 allows the lens assembly 3 to expand when the temperature of the light module increases. Indeed, the edge 428 is lifted by the pressure exerted by the lens assembly 3 as it expands.

[0048] Once the first part 421 and the second part 422 are assembled, these two parts form a housing in which the lens assembly 3 is housed. This housing constitutes the second support element 42.

[0049] In the illustrated example, each of the three lenses—the first support element 41 and the second element 42—expands as the temperature changes. Here, each of these elements is made from a material with a positive coefficient of thermal expansion; that is, these elements expand and increase in size as the temperature rises. However, the coefficients of thermal expansion of these elements are different, and this, along with the previously described setup, helps to limit the defocusing of the projection optics. In other words, the arrangement of the light module described above and the different composition of certain elements within this light module allow the focal plane F to be maintained at a desired location, here approximately at the level of the first face 51 of slide 5, despite the temperature increase within the module.

[0050] We will explain in detail the operating principle of the concept presented in support of the [ Fig.5 ].

[0051] There [ Fig.5 ] includes a first figure 5A illustrating the light module 1 at ambient temperature T0 and a second figure 5B illustrating the light module 1 at a temperature T1 higher than the ambient temperature T0. As observed in these figures, the lens set 3, the first support element 41 and the second support element 42 change in dimensions and / or position when going from the ambient temperature T0 to the higher temperature T1 while the focal plane F is maintained in the same place in both cases.

[0052] In the illustrated example, the first support element 41 is made of a material with a first coefficient of thermal expansion α1. The second support element 42 is made of a material with a second coefficient of thermal expansion α2. The lens assembly 3 has a third coefficient of thermal expansion α3. Here, these coefficients are listed in descending order of their value as follows: the first coefficient of thermal expansion α1; the third coefficient of thermal expansion α3; and the second coefficient of thermal expansion α2.

[0053] If the retaining element 4 had not been present, the expansion of the lens assembly 3 due to a temperature increase in the module would have caused the focal plane F to move towards the fixed base 7 as shown by arrow D in the illustration. figure5A until reaching the position of the focal plane F' illustrated on the figure 5A at temperature T1. Note that the final position of the focal plane F due to the expansion of the lens assembly 3 in the absence of the retaining element 4 is shown on the figure 5A to facilitate understanding and is not related to the situation of the figure 5A at ambient temperature T0.

[0054] The displacement distance of the focal plane F, called the second distance d2, depends on the temperature variation: d 2 = f ΔT with, here: ΔT = T1 -T0.

[0055] In the light module of the illustrated example, when the temperature increases, the lens assembly 3, arranged in the retaining element 4, expands in a direction opposite to the fixed base 7, as represented by arrow C shown on the figure 5B This expansion is possible thanks to the configuration of the second support element 42 with the elastically deformable member 422 described previously. Furthermore, since the second support element 42 has a coefficient of thermal expansion α2 lower than that (α3) of the lens assembly 3, this second element forces the assembly 3 to expand more in one direction than the other. Here, the assembly 3 expands more on the side of the second part 422 than on the side of the first part. Moreover, when the temperature drops, the second support element 42 contracts more than the lens assembly 3 to ensure a tight fit for the assembly 3.

[0056] The expansion of the lens assembly (3) causes a displacement of the focal plane F. In practice, and without limitation, the displacement of the focal plane F at a given temperature variation is calculated by a thermo-optical simulation using the contact area between the first element and the fixed base as a reference point. This calculation can be performed for each point within the operating temperature range.

[0057] Knowing the behavior of the lens assembly 3 and the displacement of the focal plane, the first and second elements 41 and 42 are designed to position the focal plane F at the level of the first face 51 of the slide despite the expansion. Specifically, the difference between the coefficient of thermal expansion of the first element 41 (α1) and that of the second element 42 (α2) must be large enough to displace the lens assembly 3 in the opposite direction to the displacement of the focal plane F and by a distance approximately equal to the displacement distance of the focal plane F.

[0058] Indeed, when the temperature increases to the value T1, the first support element 41 elongates in the direction opposite to the fixed base 7, represented by arrow A on the figure 5B The length of the first support element 41 evolves from an initial value L0 at ambient temperature T0 to a higher value L1 at temperature T1.

[0059] Simultaneously, the second support element 42 extends towards the fixed base 7, represented by arrow B. Here, it is the first part 421 that extends towards the fixed base 7, since the other end of the first part is connected to the first support element 41. The extension of the second support element 42 reflects the expansion of the lens assembly 3. The second support element 42 acts as an intermediary, allowing the assembly 3 to expand and, at the same time, being displaced by the deformation of the first support element. This displacement shifts the lens assembly 3 in the opposite direction to the movement of the focal plane F. The value of the displaced distance depends on the coefficients of thermal expansion of the first and second support elements 41 and 42.

[0060] Indeed, the deformation of the first support element 41 and the second support element 42 results in the lens assembly 3 being displaced in the opposite direction to the fixed base 7, represented by arrow E, by a first distance d1. This distance depends on the elongation of each of the first and second support elements 41, 42 and their respective coefficients of thermal expansion: d 1 = α 1 − α 2 × L 0 × ΔT with here: L 0: the initial length of the first support element 41; ΔT = T 1 − T 0

[0061] The focal plane F associated with the lens set 3 is moved in the same way as this set, that is to say in the opposite direction to the fixed base 7 and by a value of the first distance d1.

[0062] Thus, in order to have the focal plane F positioned relatively close to the initial location, or even in the same place as before the temperature increase, the rise of the assembly 3 of lenses must compensate for the displacement of the focal plane F due to the phenomenon of expansion.

[0063] In other words, in addition to the fact that the lens assembly 3 and the focal plane F move in opposite directions, the first distance d1 and the second distance d2 must be approximately equal: dl = d2 (to within + / - 10%). This is achieved by a suitable choice of the first and second coefficients of thermal expansion α1 and α2.

[0064] The result obtained is illustrated on the figure 5BRaising the lens assembly (3) raises the focal plane F' to position F" which is in the same location as the focal plane F at room temperature. Of course, position F" may not be exactly in its initial location, but in this case, it is close to it to ensure good image quality projected by the light module.

[0065] Therefore, the light module 1, as described, solves the defocusing problem encountered when the temperature inside the module increases. Since the focal plane is maintained on the first face of the slide, the projected image remains sharp throughout the module's use, regardless of the duration.

Claims

1. Light module (1) comprising: - a fixed mount (7) intended to act as a support for a light source (2); - a projection optic (3) that has a focal plane (F) and is designed to project a light beam from the light rays emitted by the light source (2); - a member (4) for holding the projection optic (3), said member comprising: ▪ a first support element (41); ▪ a second support element (42) that acts as a support for the projection optic; wherein: - the second support element (42) is arranged so as to allow the thermal expansion of the projection optic (3), causing the focal plane (F) to shift in a first direction (D); - the first support element (41) exhibits a first coefficient of thermal expansion (α1), the second support element exhibiting a second coefficient of thermal expansion (α2) which is different from the first coefficient of thermal expansion; and - the first support element (41) is connected on one side to the fixed mount (7) and on the other side to the second support element (42) so as to shift the second support element (42) during the deformation of the first support element (41) in a second direction (C) opposite to the first direction (D); Characterized in that - the second support element (42) comprises two separate parts (421, 422) - the second support element (42) comprises a first part (421) and a second part (422) which are fitted one in the other so as to form an accommodating space for the projection optic (3), one of the two parts supporting the projection optic on a first side (31) of the projection optic and the other part comprising an elastically deformable member bearing on the projection optic on a second side (32) on the opposite side from the first side (31).

2. Light module according to Claim 1, characterized in that: - when the temperature varies from an initial value (T0) to a final value (T1): • the thermal expansion of the projection optic (3) causes the focal plane (F) to shift by a first distance (d1), and ▪ the deformation of the first support element (41) shifts the second support element by a second distance (d2); and wherein the first coefficient of thermal expansion (α1) and the second coefficient of thermal expansion (α2) are defined such that the first distance (d1) is substantially equal to the second distance (d2).

3. Light module according to Claim 1 or according to Claim 2, characterized in that the second coefficient of thermal expansion (α2) is lower than the first coefficient of thermal expansion (α1).

4. Light module according to Claim 1, characterized in that the first support element (41) is in contact with the mount (7) in a first contact zone (411) and in contact with the second support element (42) in a second contact zone (412) situated on the opposite side from the first contact zone (411).

5. Light module (1) according to one of the preceding claims, characterized in that the first side (31) of the projection optic (3) is oriented towards the light source (2).

6. Light module (1) according to the preceding claim, characterized in that the projection optic (3) comprises a central zone (311) that realizes an optical function, and a peripheral zone (312) surrounding the central zone (311), the second support element (42) being arranged so as to at least partially conform to the shape of the peripheral zone (312).

7. Light module (1) according to one of the preceding claims, characterized in that the first and second support elements (41, 42) are connected together by adhesive bonding or by snap-fastening.

8. Light module (1) according to one of the preceding claims, characterized in that it comprises a slide (5) disposed upstream of the projection optic (3) in the direction of propagation of the light rays in the light module, the slide having a first face (51) that bears a pattern to be projected and is oriented towards the projection optic, and the desired location of the focal plane (F) being on said first face or in the vicinity of said first face.

9. Light module (1) according to the preceding claim, characterized in that the fixed mount (7) also acts as a support for the slide (5).

10. Light module (1) according to one of the preceding claims, characterized in that the projection optic (3) comprises a plurality of lenses (30) which are stacked one on top of another.

11. Lighting device for a motor vehicle, characterized in that it comprises a light module according to one of the preceding claims.

12. Lighting device according to the preceding claim, characterized in that it comprises a housing, and in that the fixed mount (7) of the light module (1) is connected to the housing.