Optical element for the optical module of a motor vehicle

Abstract

TITLE: Optical element for a motor vehicle optical module. Optical element (1) for a motor vehicle optical module comprising a first optical plate (2) and a second optical plate (3) superimposed and held together by means of at least one intermediate layer (4) disposed between the first optical plate (2) and the second optical plate (3) and comprising a first adhesive fluid (41), of the mechanical adhesive type, arranged in a continuous bead delimiting a closed frame, and a second fluid (42) disposed within the frame delimited by the first adhesive fluid (41). Figure for the abbreviation: Figure 1

Description

Title of the invention: Optical element for an automotive vehicle optical module

[0001] The invention relates to an optical element for an optical module of a motor vehicle. It also relates to a method for manufacturing such an optical element for an optical module of a motor vehicle.

[0002] Motor vehicles are conventionally equipped with lighting devices, such as headlights or projectors, particularly at the front, for example, intended to illuminate the road ahead of the vehicle at night or in low-light conditions. A lighting device comprises at least one light module, also called an optical module, including a light source and an optical element that transmits the light emitted by the light source according to predefined lighting characteristics.

[0003] As is known, the optical element may comprise a plurality of optical plates, also called lenses, superimposed one on top of the other. Optionally, an intermediate plate may be interposed between the optical plates. In order to obtain such a superposition and to keep the different plates joined together, the optical plates are conventionally molded, each on one of the two faces of the intermediate plate, and hardened.

[0004] One disadvantage of such an optical element lies in its high manufacturing cost.

[0005] To solve such a problem, it is known to bond the different plates together using adhesives, particularly glues. Among known adhesives, mechanical glues typically have characteristics unsuitable for use on the optical surface of optical plates, as they tend to degrade the light beam passing through them. Optical glues have characteristics that prevent them from impacting the light beam.

[0006] However, such adhesives are mechanically unsuitable because they tend to be very liquid, in other words, they have low viscosity, thus making their application complex. For example, in order to apply optical adhesive to a precise thickness, it is necessary to use specific solutions whose composition may vary during manufacturing. As a result, significant losses of optical adhesive are observed during production, thus generating additional costs and variability in the manufacturing of optical elements. Adhesives with suitable mechanical and optical characteristics are few in number and have the disadvantage of being expensive.

[0007] The invention falls within this context and aims to offer an alternative to the elements optics are known to be less expensive and less complex to manufacture.

[0008] To this end, the invention relates to an optical element for an optical module of a motor vehicle comprising a first optical plate and a second optical plate superimposed one on top of the other and held together by means of at least one intermediate layer disposed between the first optical plate and the second optical plate, the at least one intermediate layer comprising: • a first adhesive fluid, of the mechanical glue type, arranged in a continuous bead delimiting a closed frame; • a second fluid placed in the frame delimited by the first adhesive fluid.

[0009] In particular, the first optical plate and the second optical plate each comprise an optical surface, in particular having a central position within the optical plate considered, said optical surfaces being arranged opposite each other, the frame formed by the first adhesive fluid being arranged at a non-zero distance from said optical surfaces and: • the second fluid being disposed in contact with and / or opposite at least one of said optical surfaces; and / or • the second fluid being arranged so as to extend over a portion of the area of ​​the first optical plate and / or the second optical plate at least equal to an area of ​​at least one of said optical surfaces so as to cover it totally.

[0010] Optionally, the first adhesive fluid is selected from: • an adhesive with a viscosity greater than or equal to 100 mPa·s and / or with a Young's modulus greater than or equal to 5 MPa, or even 7 MPa; and / or • an opaque glue.

[0011] Optionally, the second fluid is a fluid defined by a refractive index equal to, or substantially equal to, a refractive index of the glass, plastic and / or material of the first optical plate and / or the second optical plate.

[0012] In particular, the second fluid is selected from: • a liquid fluid, especially a transparent one, such as water; or • a second adhesive fluid, in particular of the optical glue type.

[0013] In particular, the first optical plate and / or the second optical plate: • is made of a plastic material selected from polymethyl methacrylate, polycarbonate, a cycloolefin copolymer or a cycloolefin polymer; and / or • includes optical patterns larger than 1 mm.

[0014] Also, the optical element optionally includes, in addition: • at least one intermediate plate, interposed between the first optical plate and the second optical plate; • a plurality of intermediate layers, at least one intermediate layer, hereafter referred to as the first intermediate layer, being disposed between the first optical plate and the intermediate plate, a second intermediate layer being disposed between the intermediate plate and the second optical plate.

[0015] For example, the second intermediate layer comprises: • a first adhesive fluid, of the mechanical glue type, arranged in a continuous bead delimiting a frame; • a second fluid placed in the frame delimited by the first adhesive fluid.

[0016] The invention also relates to a method for manufacturing an optical element for an optical module of a motor vehicle, comprising: • a manufacturing step involving molding, particularly injection molding, of a first optical plate and a second optical plate; and • a step of applying at least one intermediate layer comprising the positioning of a first adhesive fluid, of the mechanical glue type, on a first face of the first optical plate, so as to form a continuous bead delimiting a closed frame, and the application of a second fluid within the closed frame delimited by the first adhesive fluid; then • and a step of positioning the second optical plate so as to form a stack such that at least one intermediate layer is disposed between the first optical plate and the second optical plate.

[0017] In particular, the manufacturing process is carried out in such a way that: • the first adhesive fluid is applied so as to have a thickness between 100 and 300 µm at the time of application, the second fluid then being applied with a thickness strictly less than that of the first adhesive fluid; and / or • The first adhesive fluid is placed on a contour of the first optical plate so that the intermediate layer extends over the entire surface of the first optical plate.

[0018] Optionally, the manufacturing process further comprises, prior to the positioning of the second optical plate: • the positioning of an intermediate plate on the assembly formed by the first optical plate and at least one intermediate layer; then • a step of applying an intermediate layer to the inter- plate median.

[0019] Other details, features and advantages will become clearer upon reading the detailed description given below, by way of example and not limitation, in relation to the various embodiments illustrated in the following figures:

[0020] Fig. 1 is a schematic side view representation of a first example of the embodiment of an optical element for an automotive optical module, in particular a light module.

[0021] Fig. 2 is a top view representation of part of the optical element illustrated in Fig. 1.

[0022] Fig. 3 is a schematic side view representation of a second example of an embodiment of the optical element.

[0023] Fig. 4 is a schematic representation of an example embodiment of the light module.

[0024] Figures 1 to 4 schematically illustrate examples of the embodiment of an optical element 1 for a light module 10 of a motor vehicle, also referred to as the optical module. The light module 10 is, by way of non-limiting example, a headlight, in particular a front headlight. The light module 10 comprises at least one light source 11 capable of generating a light beam 12 passing through one or more optical element(s) according to the invention so as to be projected onto the road surface.

[0025] By convention in the description below, the terms "first" and "second" are intended to distinguish similar components and not to define a hierarchy within said components.

[0026] Generally, the optical element 1 according to the invention comprises a first optical plate 2 and a second optical plate 3 superimposed one on top of the other, in particular superimposed along a first direction 100. "Superimposed" means that said plates are arranged one above the other along a given direction, here for example the first direction 100, whether or not they are in direct contact with each other. The optical element 1 further comprises at least one intermediate layer 4 configured to hold, directly or indirectly, the first optical plate 2 and the second optical plate 3 together. "Layer" here means a single portion of a given thickness of the optical assembly 1, said thickness being defined here along the first direction 100.In this case, at least one intermediate layer is an adhesive layer, also described as a bonding layer, meaning that it is at least partially adhesive.

[0027] The first optical plate 2 and the second optical plate 3, also referred to as optical lenses, are made of materials chosen for their properties optical properties with respect to the light source 11 used. Also, preferably, the materials used for the first optical plate 2 and for the second optical plate 3 have compatible optical properties. Optionally, the materials used have optical and / or mechanical properties compatible with specific manufacturing techniques for the optical element 1, further described below, such as crosslinking techniques with an adhesive fluid or curing by heat treatment.

[0028] The first optical plate 2 and the second optical plate 3 are preferably made of a plastic material, in particular a resin. For example, without limitation, the first optical plate 2 and / or the second optical plate 3 comprise a plastic material selected from polymethyl methacrylate, also known by the acronym PMMA, polycarbonate, or PC, a cycloolefin copolymer, or COC, or a cycloolefin polymer, or COP.

[0029] The first optical plate 2 comprises a first face 21, configured to face the second optical plate 3 and / or at least one intermediate layer 4, and a second face 22, opposite the first face 21. The same applies to the second optical plate 3, which comprises a first face 31 and a second face 32. Optionally, the first optical plate 2 and / or the second optical plate 3 comprise optical patterns 5. These optical patterns 5 are notably located on the second face 22 of the first optical plate 2 and / or on the second face 32 of the second optical plate 3. The optical patterns 5 make it possible to induce a particular optical effect, each pattern behaving as an independent optical cell.

[0030] The optical patterns 5 may have varying shapes and / or dimensions, between the first optical plate 2 and the second optical plate 3, or even within the same optical plate. According to a non-limiting example, the optical patterns 5 have at least one dimension greater than 1 mm, for example, a height defined along the first direction 100 within the optical element 1, or a width and / or a length defined along a direction orthogonal to the first direction 100. For example, the optical patterns 5 may have the form of a regular mesh. Alternatively, the optical patterns 5 may have a more complex geometry, for example, such as to include irregular patterns and / or patterns of different sizes and / or shapes within the optical plate in question.

[0031] At least one intermediate layer 4 is disposed between the first optical plate 2 and the second optical plate 3. It is thus interposed between the first optical plate 2 and the second optical plate 3 along the first direction 100. According to one embodiment, at least one intermediate layer 4 is disposed on the first optical plate 2, in particular on the first face 21. In particular, at least an intermediate layer 4 extends over all or part of the surface of the first face 21 of the first optical plate 2.

[0032] At least one intermediate layer 4 allows the first optical plate 2 and the second optical plate 3 to be held together. According to various embodiments described below, the at least one intermediate layer 4 can achieve such bonding directly, by being positioned in contact with the first optical plate 2 and the second optical plate 3, or indirectly, by contact with a separate plate of the second optical lacquer 3. Also, according to some embodiments, the optical element 1 optionally comprises a plurality of intermediate layers. Therefore, it is understood that the following description, given with reference to an intermediate layer 4, can be applied mutatis mutandis to all or part of a plurality of intermediate layers of the optical element 1.

[0033] The intermediate layer 4 comprises a first adhesive fluid 41 and a second fluid 42. The first adhesive fluid 41 is disposed within the intermediate layer 4, here for example on the first face 21 of the first optical plate 2, so as to form a continuous bead delimiting a closed frame. The second fluid 42 is disposed, within the intermediate layer 4, in the frame delimited by the first adhesive fluid 41. The first adhesive fluid 41 thus delimits a location, or compartment, with at least one of the first optical plate 2 and / or the second optical plate 3, suitable for receiving the second fluid 42.

[0034] The first adhesive fluid 41 is an adhesive, particularly a mechanical adhesive. A "mechanical adhesive," or structural adhesive, is understood to be an adhesive with mechanical properties suitable for fastening, i.e., for joining two parts, particularly for transmitting mechanical forces greater than or equal to 5 MPa, or even 7 MPa, in a given environment for the expected lifespan of the object. The mechanical properties sought in the present invention include, in particular, a Young's modulus greater than or equal to 5 MPa, or even 7 MPa. Preferably, the first adhesive fluid 41 has a viscosity greater than or equal to 100 mPa-s, or even 500 mPa-s, and / or the first adhesive fluid 41 has a Young's modulus greater than or equal to 5 MPa, or even 7 MPa.For example, mechanical adhesive is selected from among methacrylate adhesive, cyanoacrylate adhesive, polyurethane adhesive, silicone adhesive, epoxy resin, also known as polyepoxide, modified epoxy resin, acrylic resin, or a mixture of the aforementioned examples.

[0035] Additionally or alternatively, the first adhesive fluid 41 is optionally opaque, in particular an opaque adhesive, or tinted. Such a principle advantageously makes it possible to limit, or even prevent, light leakage at the level of lateral portions of the optical element 1, that is to say at the level of a thickness of the in- layer termedial 4.

[0036] The second fluid 42 is an optical fluid, that is, a fluid with characteristics that have little or no effect on the light beam 12 passing through the optical element 1. For example, the second fluid 42 has a refractive index equal to, or substantially equal to, the refractive index of glass, plastic, or a material used for the first optical plate 2 and / or the second optical plate 3, that is, a material of at least one of the plates to be bonded. "Substantially equal" here means a variation of approximately ±10% in the refractive index. In particular, the second fluid 42 is transparent and / or untinted.

[0037] According to one embodiment, the second fluid 42 is a liquid fluid, such as water. Advantageously, the second fluid 42 can thus remain in a liquid state in the optical element 1, fitted in the vehicle, without it being necessary to solidify it during the manufacture of the optical element 1, as described below with reference to the manufacturing process according to the invention.

[0038] Alternatively, the second fluid 42 is a second adhesive fluid 42a. In particular, the second adhesive fluid 42a is an optical adhesive. As is known, optical adhesives have optical properties that allow for use without, or with little risk of, affecting the light beam 12. In particular, as indicated above, an optical adhesive typically has a refractive index close to or equal to that of the glass, plastic, and / or materials of the first optical plate 2 and / or the second optical plate 3. Optical adhesives, however, have the disadvantage of being very liquid, thereby making their application complex and likely to generate overflows beyond the surface of the optical plate to which they are applied. The invention advantageously allows for the delimitation of a partially enclosed space into which the second fluid 42 can be poured without risk of overflow.The first adhesive fluid 41 thus also ensures the sealing of the final optical element 1.

[0039] Thus, for example, the second optical fluid 42 can be selected from optical adhesives of the epoxy, modified epoxy, acrylate, urethane-acrylate, polyurethane, silicone type or a mixture of the aforementioned examples.

[0040] In particular, as shown in dashed lines in [Fig. 1] or 2, the first optical plate 2 and the second optical plate 3 each comprise an optical surface 6, corresponding to a surface, demarcated or not, intended for the passage of the light beam 12, in particular a central surface of the plate in question. The optical surfaces 6 are arranged directly or indirectly opposite each other along the first direction 100. In particular, each optical surface 6 has a central position within the optical plate comprising it. The frame formed by the first adhesive fluid 41 can then be particularly arranged so as to include the optical surface 6 of the first optical plate 2 and / or the second optical plate 3. The first adhesive fluid 41 can, for example, be arranged at a non-zero distance from said optical surfaces 6. Conversely, the second fluid 42 is arranged in contact and / or opposite at least one of said optical surfaces 6. In this way, the light beam 12 passing through the optical element 1 and intended to be projected onto the road passes only through the second fluid 42.

[0041] Alternatively or additionally, the second fluid 42 is disposed on a portion of the area of ​​the first optical plate 2 and / or the second optical plate 3 at least equal to an area of ​​the optical surface 6 proper to the optical plate considered so as to cover it totally.

[0042] According to one embodiment, the first adhesive fluid 41 is disposed along edges of the first optical plate 2 and / or the second optical plate 3 so as to follow a contour of at least one of said plates.

[0043] In particular, optionally, the intermediate layer 4 has, within the optical element 1, a thickness of between 100 and 300 pm. The thickness here corresponds to the dimension defined along the first direction 100.

[0044] Optionally, the optical element 1 further comprises at least one optical mask 7. The optical mask 7 is designed to allow the light beam 12 to pass only according to a predefined pattern. To this end, it can be made of an opaque material, having at least one partially transparent opening, the contours of which correspond to the shape of the light pattern to be projected. The optical mask 7 can be formed by any known means, for example, by depositing a coating that is not transparent to the light used in an optical module. Such a coating can, for example, be deposited by a vapor deposition technique, known by the acronym PVD, optionally followed by laser finishing. Alternatively, it can be deposited by a lithography technique. The mask comprises, for example, a metallic material, such as aluminum or chromium.

[0045] According to a non-limiting embodiment, the optical mask 7 is disposed on the first face 21 of the first optical plate 2. In particular, it extends beyond the first face 21 so that it is at least partially contained within the thickness of at least one intermediate layer 4. Alternatively, the first optical plate 2 may include a recess in which the optical mask 7 is disposed so as to extend flush with at least a portion of the first face 21. The intermediate layer 4 may thus be in contact with the first optical plate 2 and / or the optical mask 7. Preferably, the optical mask 7 extends only over a portion of the first face of the first optical plate 2.

[0046] According to an alternative embodiment, illustrated in Figures 3 or 4, the optical element The optical element 1 further comprises at least one intermediate plate 8, disposed between the first optical plate 2 and the second optical plate 3. This intermediate plate 8 is thus interposed between the first optical plate 2 and the second optical plate 3, particularly along the first direction 100. For example, the intermediate plate 8 is made of glass, advantageously Flint glass. Alternatively, it may be made of plastic. In this case, the optical element 1 comprises a single intermediate plate 8. However, it is understood that the present invention extends to an optical element 1 comprising a plurality of intermediate plates.

[0047] In order to keep the first optical plate 2, the second optical plate 3 and at least one intermediate plate 8 together, the optical element 1 comprises a plurality of intermediate layers 4. In particular, the optical element 1 comprises, for a total number n of intermediate plates, an n+1 number of intermediate layers.

[0048] The optical element 1 as illustrated in Figures 3 and 4 comprises two intermediate layers 4 and an intermediate plate 8. The at least one intermediate layer 4 as described above is hereafter referred to as the first intermediate layer 4a. It is disposed between the first optical plate 2 and the intermediate plate 8. A second intermediate layer 4b is disposed between the intermediate plate 8 and the second optical plate 3.

[0049] According to one embodiment, the second intermediate layer 4b may comprise a simple optical adhesive.

[0050] According to a preferred embodiment, the second intermediate layer 4b comprises, similarly to the first intermediate layer 4a, a first adhesive fluid 41, of the mechanical adhesive type, arranged in a continuous bead delimiting a closed frame, and a second fluid 42 disposed within the frame delimited by the first adhesive fluid 4B. Therefore, the entire preceding description referring to at least one intermediate layer 4 can be extended to the second intermediate layer 4b. It should be noted that the first intermediate layer 4a and the second intermediate layer 4b can be made identically or differently. They can thus comprise a first adhesive fluid 41, a second fluid 42, a thickness, and / or a similar or different frame position and / or dimensions.In the illustrated example, the first intermediate layer 4a and the second intermediate layer 4b are made with similar characteristics in order to simplify the process and limit manufacturing costs.

[0051] Also, when the optical element 1 includes, optionally, an optical mask 7, the latter can be arranged at the level of the intermediate plate 8. It can then be arranged on at least one face of the intermediate plate 8, for example turned towards the first optical plate 2 or towards the second optical plate 3. Specifically, the optical mask 7 is arranged to project from the face in question, as described above. The optical mask 7 is then at least partially located within the thickness of the second intermediate layer 4b or the first intermediate layer 4a. Alternatively, the intermediate plate 8 includes a recess as described previously.

[0052] The invention also extends to a method for manufacturing an optical element 1, in particular an optical element 1 as previously defined. It is understood that the characteristics and alternatives described above, relating to the optical element 1, the first optical plate 2, the second optical plate 3, at least one intermediate layer 4, at least one intermediate plate 8, or the optical mask 7, extend to these same elements mentioned in the context of the method according to the invention.

[0053] The process includes a manufacturing step by molding the first optical plate 2 and the second optical plate 3. Optionally, but preferably, the first optical plate 2 and / or the second optical plate 3 may be obtained by injecting a plastic material into a mold. Alternatively, this step includes casting, which consists of filling a mold of the desired shape with a liquid material, which gradually solidifies inside the mold. Alternatively again, any known type of molding may be implemented.

[0054] Optionally, when an optical element 1 as illustrated in [Fig. 3] is produced, the process further comprises a manufacturing step of at least one intermediate plate 8 as described above. For example, the at least one intermediate plate 8 is made of glass. Alternatively, it is made of a plastic material and can, for example, be obtained by molding according to any of the aforementioned techniques.

[0055] Alternatively, when the optical element 1 includes an optical mask 7 as described above, the manufacturing process includes a step of applying said mask to at least one of the plates of the optical element 1. The plate in question may be the first optical plate 2, as illustrated in [Fig. 3], at least one intermediate plate 8, or, according to an alternative not shown, the second optical plate 3. For example, the optical mask 7 is formed on the first face of the first optical plate 2 or the second optical plate 3, or on at least one face of at least one intermediate plate 8. As indicated above, the optical mask 7 may be formed by any known means, for example by depositing a coating that is not transparent to the light used in a light module 10, in particular a coating comprising a metallic material such as aluminum or chromium.Such a coating is, for example, applied via a vapor phase deposition technique optionally followed by . laser retouching or via a lithography technique.

[0056] The method includes a step of applying at least one intermediate layer 4 to the first optical plate 2. Such an application initially comprises positioning the first adhesive fluid 41, of the mechanical adhesive type as described above, on the first face 21 of the first optical plate 2 so as to form a continuous bead delimiting a closed frame. The application of the intermediate layer 4 then comprises applying the second fluid 42 as described previously so that it is disposed within the closed frame delimited by the first adhesive fluid 41. The first adhesive fluid 41 and the second fluid 42 can be applied manually or automatically by means of an applicator.

[0057] Optionally but preferably, at the time of application, the first adhesive fluid 41 is applied so as to have a thickness between 100 and 300 pm, in particular defined here along the first direction 100. The second fluid 42 is then applied with a thickness strictly less than the thickness of the first adhesive fluid 4L. For example, the first adhesive fluid 41 is disposed along a contour of the first optical plate 2, i.e. at the edges of said plate, so that the intermediate layer 4 extends over the entire first face of the first optical plate 2. Alternatively, the first fluid is disposed at a distance from the edges of the first optical plate 2 so as to extend only over a part of the first face of the first optical plate 2.

[0058] When an optical element 1 as illustrated in [Fig. 2] is produced, the manufacturing process then includes a step of positioning the second optical plate 3 so as to form a stack such that at least one intermediate layer 4 is disposed between the first optical plate 2 and the second optical plate 3, in particular along the first direction 100. In such an embodiment, the first face 21 of the second optical plate 3 is then in contact with at least one intermediate layer 4. The pressure exerted by the positioning of the second optical plate 3 advantageously allows the crushing and / or spreading of at least a part of the at least one intermediate layer 4, particularly of the first adhesive fluid 4L. This thus makes it possible to avoid the presence of air between the different optical plates.It also advantageously allows the homogenization of the thickness of at least one intermediate layer 4 and / or the distribution of at least one intermediate layer 4 over the surface of the first optical plate 2. The first adhesive fluid 41 then ensures the sealing of the optical element 1 at the level of its thickness and prevents the overflow of the second fluid 42.

[0059] Optionally, the manufacturing process includes hardening all or part of at least one intermediate layer 4. In particular, at least the first The adhesive fluid 41 is cured. According to one embodiment, such curing is achieved by cross-linking with ultraviolet radiation. In particular, the ultraviolet radiation is applied through the first optical plate 2 when it comprises a material at least partially transparent to the cross-linking radiation. Alternatively, this radiation can be applied through the second optical plate 3. According to yet another alternative, the curing of all or part of at least one intermediate layer 4 is achieved by heat treatment, for example at a temperature of 80°C or higher. In such a variant, the materials of the individual plates are chosen so as to withstand the heat treatment temperature.

[0060] Alternatively, to manufacture an optical element 1 as illustrated in [Fig. 3], the manufacturing process further comprises: - the positioning of at least one intermediate plate 8 on the assembly formed by the first optical plate 2 and at least one intermediate layer 4; then - a step of applying an intermediate layer on the intermediate plate 8, hereinafter referred to as the second intermediate layer 4b, distinct from the at least one intermediate layer 4 as described above, hereinafter referred to as the first intermediate layer 4a.

[0061] These steps are performed prior to the positioning of the second optical plate 3 and subsequent to the application of the first intermediate layer 4a described above. Furthermore, the positioning of at least one intermediate plate 8 is performed prior to the curing of at least a portion of the first intermediate layer 4a.

[0062] The positioning of the at least one intermediate plate 8 is carried out similarly to the positioning step of the second optical plate 3 as described above, so the preceding description applies mutatis mutandis. The at least one intermediate plate 8 is arranged to form a stack such that the at least one intermediate layer 4, here referred to as the first intermediate layer 4a, is positioned between the first optical plate 2 and the at least one intermediate plate 8 along the first direction 100. The positioning of the at least one intermediate plate 8 allows, in particular, the crushing and / or spreading of at least a portion of the at least one intermediate layer 4 and, by extension, the homogenization of the thickness of the at least one intermediate layer 4.

[0063] Once at least one intermediate plate 8 is in position, the curing of the first intermediate layer 4a is optionally carried out. When the curing is performed by cross-linking using ultraviolet radiation, this can be carried out through the first optical plate 2 and / or at least one intermediate plate 8.

[0064] The second intermediate layer 4b is then applied to the face of at least one intermediate plate 8 opposite the face in contact with the first intermediate layer 4a. According to one embodiment, the second intermediate layer 4b may comprise a simple optical adhesive. Alternatively, the second intermediate layer 4b comprises a first adhesive fluid 41 and a second fluid 42 as described above with reference to the at least one intermediate layer 4. The step of applying such a layer applies mutatis mutandis to the second intermediate layer 4b, except that it is disposed on the at least one intermediate plate 8 instead of the first optical plate 2.

[0065] The second optical plate 3 can then be placed on the second intermediate layer 4b in a manner similar to that described previously with reference to its positioning on the first intermediate layer 4a. Likewise, the hardening of the second intermediate layer 4b can be carried out in a manner similar to that described with reference to the first intermediate layer 4a. Alternatively, the hardening of both intermediate layers can be carried out simultaneously.

[0066] Thus, the present invention proposes a less complex and less expensive optical element. The at least one intermediate layer of the optical element is advantageously adapted to limit the presence of air between the different plates, which would be detrimental to the optical performance of the optical element. Also, the use of a first opaque adhesive fluid makes it possible to broaden the range of adhesives that can be used and to limit light leakage through the thickness of the optical element.

[0067] The present invention cannot, however, be limited to the means and configurations described and illustrated herein and it also extends to any equivalent means or configuration and to any technically operative combination of such means insofar as they ultimately fulfill the functionalities described and illustrated in this document.

Claims

Claims

1. Optical element (1) for an optical module of a motor vehicle comprising a first optical plate (2) and a second optical plate (3) superimposed on each other and held integral with each other by means of at least one intermediate layer (4) arranged between the first optical plate (2) and the second optical plate (3), the at least one intermediate layer (4) comprising: • a first adhesive fluid (41), of the mechanical glue type, arranged in a continuous bead delimiting a closed frame; • a second fluid (42) arranged in the frame delimited by the first adhesive fluid (41).

2. Optical element (1) according to the preceding claim, wherein the first optical plate (2) and the second optical plate (3) each comprise an optical surface (6), in particular having a central position within the optical plate in question, said optical surfaces (6) being arranged opposite one another, the frame formed by the first adhesive fluid (41) being arranged at a non-zero distance from said optical surfaces (6) and: • the second fluid (42) being arranged in contact with and / or opposite at least one of said optical surfaces (6); and / or • the second fluid (42) being arranged so as to extend over a portion of the area of the first optical plate (2) and / or of the second optical plate (3) at least equal to an area of at least one of said optical surfaces (6) so as to cover it completely.

3. Optical element (1) according to one of the preceding claims, in which the first adhesive fluid (41) is selected from: • an adhesive having a viscosity greater than or equal to 100 mPa.s and / or having a Young's modulus greater than or equal to 5 MPa, or even 7 MPa; and / or • an opaque adhesive.

4. Optical element (1) according to one of the preceding claims, wherein the second fluid (42) is a fluid defined by a refractive index equal, or substantially equal, to a refractive index of the glass, of a plastic and / or of a material of the first optical plate (2) and / or of the second optical plate (3).

5. Optical element (1) according to one of the preceding claims, in which the second fluid (42) is selected from: • a liquid fluid, in particular transparent, such as water; or • a second adhesive fluid (42a), in particular of the optical glue type.

6. Optical element (1) according to one of the preceding claims, in which the first optical plate (2) and / or the second optical plate (3): • is made of plastic material selected from polymethyl methacrylate, polycarbonate, a cycloolefin copolymer or a cycloolefin polymer; and / or • comprises optical patterns (5) of dimensions greater than 1 mm.

7. Optical element (1) according to one of the preceding claims, further comprising: • at least one intermediate plate (8), interposed between the first optical plate (2) and the second optical plate (3); • a plurality of intermediate layers, the at least one layer, hereinafter referred to as the first intermediate layer (4a), being arranged between the first optical plate (2) and the intermediate plate (8), a second intermediate layer (4b) being arranged between the intermediate plate (8) and the second optical plate (3).

8. Method of manufacturing an optical element (1) for an optical module of a motor vehicle, characterized in that it comprises: • a manufacturing step by molding, in particular by injection of a first optical plate (2) and a second optical plate (3); and a step of applying at least one intermediate layer (4) comprising the positioning of a first adhesive fluid (41), of the mechanical glue type, on a first face (21) of the first optical plate (2), so as to form a continuous bead delimiting a closed frame and the application of a second fluid (42) in the closed frame delimited by the first adhesive fluid (41); then and a step of positioning the second optical plate (3) so as to form a stack such that the at least one intermediate layer (4) is arranged between the first optical plate (2) and the second optical plate (3).

9. Method of manufacturing an optical element (1) according to the preceding claim, in which: the first adhesive fluid (41) is applied so as to have, at the time of the application step, a thickness of between 100 and 300 μm, the second fluid (42) then being applied with a thickness strictly less than the thickness of the first adhesive fluid (41); and / or the first adhesive fluid (41) is arranged on a contour of the first optical plate (2) so that the intermediate layer (4) extends over the entire surface of the first optical plate (2).

10. Method of manufacturing an optical element (1) according to claim 8. or 9, further comprising, prior to positioning the second optical plate (3): the positioning of an intermediate plate (8) on the assembly formed by the first optical plate (2) and the at least one intermediate layer (4); then a step of applying an intermediate layer (4) to the intermediate plate (8).

Images