Light module for a motor vehicle

Abstract

The invention relates to a lighting module (5) for a motor vehicle, said lighting module comprising a lighting device (5A) having a stack comprising: a) a protective panel (20), b) an intermediate layer (30) comprising at least two radar antennas (100, 101) and two parasitic antennas (200, 201) positioned between the two radar antennas, the parasitic antennas not being electrically connected, and c) a conductive layer (40) adapted to partially form a ground plane for the radar antennas, and the lighting module comprising a light source (70) emitting a light beam (Li) propagating from the conductive layer to the protective panel, the light beam having a propagation field, the parasitic antennas being positioned within the propagation field of the light beam (Li), the radar antennas being located outside the propagation field. Figure to be published with the abbreviation: Figure 2

Description

Title of the invention: Lighting module for a motor vehicle TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention relates generally to motor vehicle equipment fitted with a radar sensor.

[0002] In particular, the invention relates to a lighting module for a motor vehicle, included within that motor vehicle and comprising a radar sensor. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] A large majority of motor vehicles are now equipped with advanced driver assistance systems (or ADAS for "Advanced Driver Assistance Systems," according to the commonly used Anglo-Saxon acronym). These driver assistance systems are, for example, safety and driver assistance systems designed to help avoid potentially dangerous situations that could lead to an accident.

[0004] These driver assistance systems rely in particular on the use of detection systems equipped, for example, with radar sensors. These radar sensors include, in particular, at least one radar sensor capable of emitting radar waves.

[0005] It is known, in particular, to integrate the radar sensor directly into lighting or signaling devices. However, radar sensors must not be aesthetically visible and must not affect the performance of the lighting or signaling devices. In particular, optical phenomena such as reflection and diffraction must be avoided for the propagation of light beams used to effectively implement the lighting or signaling functions. Summary of the invention

[0006] The present invention then proposes to improve the integration of a radar sensor in a light module for a motor vehicle, intended for example to implement lighting or signaling functions, in order to guarantee efficient propagation of radar waves and light beams.

[0007] One aspect of the invention thus relates to a lighting module for a motor vehicle, said lighting module comprising a lighting device configured to implement a lighting function or a signaling function of the motor vehicle, the lighting device comprising a stack comprising:

[0008] a) a protective panel,

[0009] b) an intermediate layer comprising at least two radar antennas of a radar sensor configured to emit and / or receive associated radar waves, radar waves emitted by the radar antennas propagating towards the panel of protection, the intermediate layer also comprising at least two parasitic antennas positioned between the two radar antennas, the parasitic antennas not being electrically connected, each radar antenna comprising a first metallic mesh, each parasitic antenna comprising a second metallic mesh, the first metallic mesh having a mesh density higher than another mesh density of the second metallic mesh, and

[0010] c) the conductive layer adapted to partially form a ground plane for the radar antennas, the intermediate layer being positioned between the protective panel and the conductive layer, and

[0011] the light module also comprising a light source adapted to enable the implementation of a lighting function, the light source emitting a light beam propagating from the conductive layer to the protective panel, the light beam having an angular opening defining a propagation field, the parasitic antennas being positioned in the propagation field of the light beam, the radar antennas being located outside the propagation field of the light beam.

[0012] These arrangements are particularly advantageous because the parasitic antennas, with their lower mesh density, do not impede the propagation of the light beam (for the purpose of implementing the lighting and / or signaling functions). Indeed, the lower mesh density ensures better optical transparency (i.e., to the visible spectrum) of the lighting device compared to the parts equipped with the radar antennas. The light beam then propagates through these parts with this improved optical transparency, thus guaranteeing the effective implementation of the lighting and / or signaling functions.

[0013] In other words, the electrically connected conductive elements (here, the radar antennas) are positioned outside the propagation field of the light beam so as not to interfere with its propagation. This ensures, in particular, that the lighting and signaling functions are clearly visible from outside the vehicle to road users. Specifically, this arrangement prevents any potential diffraction phenomena during the propagation of the light beam.

[0014] In addition to the characteristics mentioned in the preceding paragraph, the light module according to the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations:

[0015] - the mesh density of the first metallic mesh is at least 10 times superior to the other mesh density of the second metallic mesh;

[0016] - a parasitic antenna is spaced from an adjacent radar antenna by a distance of the order of a wavelength of the light beam;

[0017] - two adjacent parasitic antennas are spaced a distance from each other the order of half a wavelength of the light beam;

[0018] - the angular opening of the light beam extends between -4 degrees and +4 degrees;

[0019] - the conductive layer comprises a first part and a second part, the the second part of the conductive layer being positioned opposite the parasitic antennas, the first part of the conductive layer being positioned opposite the radar antennas, the first part of the conductive layer having a surface resistance greater than another surface resistance of the second part of the conductive layer;

[0020] - the other surface resistance of the second part of the conductive layer is at least ten times smaller than the surface resistance of the first part of the conductive layer;

[0021] - the radar antennas and the parasitic antennas are glued into the layer intermediate ;

[0022] - the radar antennas and the parasitic antennas are encapsulated in the layer intermediate ;

[0023] - the thickness of the protective panel is less than 5 millimeters;

[0024] - the conductive layer comprises indium tin oxide;

[0025] - the conductive layer comprises another metallic mesh;

[0026] - one pitch of the metallic mesh of the radar antenna is smaller than another pitch of the other metallic mesh of the conductive layer;

[0027] - the intermediate layer comprises a flexible transparent material;

[0028] - the protective panel comprises a transparent polymer material;

[0029] - the light module also includes another protective panel, the layer conductive being positioned between the intermediate layer and the other protective panel;

[0030] - the other protective panel has the same thickness as the panel of protection;

[0031] - the other protective panel comprises a polymer material; and

[0032] - the protective panel forms an external window of the motor vehicle. BRIEF DESCRIPTION OF THE FIGURES

[0033] Other features and advantages of the invention will become apparent from the description, which can be read in conjunction with the figures. These figures are provided for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] [Fig. 1] Fig. 1 represents a partial schematic view of a motor vehicle within the scope of the present invention,

[0035] [Fig.2] Fig.2 represents a schematic cross-sectional view of a first example of fabrication of a lighting module for a motor vehicle according to the invention,

[0036] [Fig.3] The [Fig.3] represents a schematic view in functional form of a radar sensor included in the light module according to the invention,

[0037] [Fig.4] Fig.4 represents a schematic view of a radar antenna included in the radar sensor of [Fig.3],

[0038] [Fig. 5] Fig. 5 represents a schematic cross-sectional view of the radar antenna represented in [Fig.4], according to a section plane AA,

[0039] [Fig. 6] Fig. 6 represents a schematic cross-sectional view of a second example of the realization of the light module according to the invention, and

[0040] [Fig. 7] Fig. 7 represents a schematic cross-sectional view of a third example of the realization of the light module according to the invention.

[0041] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED DESCRIPTION

[0042] The present invention aims to provide a light module comprising a radar sensor that enables efficient propagation of radar waves and ensures efficient propagation of a light beam from a lighting or signaling device. More particularly, the light module has a structure that improves the integration of radar antennas within a radar sensor, notably to ensure that the radar sensor does not interfere with the propagation of a light beam in a lighting or signaling device.

[0043] Figure 1 shows a partial schematic view of a vehicle 1 relevant to the invention. In this description, the vehicle 1 considered is a motor vehicle. "Motor vehicle" means any type of motorized vehicle. Hereafter, the terms "vehicle" and "motor vehicle" are used to describe the vehicle relevant to the present invention.

[0044] In a conventional manner, the motor vehicle 1 includes in particular a signaling device 2 and a lighting device 3. Here, the motor vehicle 1 also includes a lidar 4. As these elements do not constitute the core of the invention, they are not described in more detail in the following.

[0045] As can be seen in [Fig. 1], a forward direction Z of movement of vehicle 1 is defined. This direction Z also corresponds to a longitudinal axis of vehicle 1 (this longitudinal axis can also be called the "vehicle axis"). An XZ plane here corresponds to the horizontal plane of vehicle 1.

[0046] The motor vehicle 1 includes a light module 5. A first example of this light module 5 is shown in [Fig. 2]. As can be seen in this figure, this light module 5 includes a light device 5A equipped with a radar sensor 10, a protective panel 20, an intermediate layer 30 and a conductive layer 40. The light module 5 also includes a light source 70.

[0047] Here, the lighting device 5A comprises a stack of layers. This stack includes the protective panel 20, the intermediate layer 30, and the conductive layer 40. It is important to note here that this stack of layers is achieved without any air gaps between the different layers concerned. In other words, the different layers comprising the lighting device 5A according to the invention are bonded together.

[0048] The overall thickness of the stack formed is, for example, less than 20 millimeters (mm). Preferably, this overall thickness is between 1 and 15 mm, and even more preferably between 1 and 12 mm.

[0049] The radar sensor 10 is configured to emit and receive RI, R2 radar waves.

[0050] In practice, the radar sensor 10 is a millimeter-wave radar sensor (with frequencies between 24 Gigahertz (GHz) and 300 GHz). Alternatively, the radar sensor is a microwave radar sensor (with frequencies between 300 Megahertz (MHz) and 81 GHz). As a further alternative, the radar sensor is a microwave radar sensor (between 1 GHz and 300 GHz).

[0051] Preferably in the present invention, the radar sensor 10 operates at a radar frequency between 76 GHz and 81 GHz. The RI radar waves are, for example, emitted over a frequency band between 100 MHz and 3 GHz. Thus, in a preferred example, if the sensor operates at a radar frequency of 77 GHz with a frequency band of 1 GHz, the radar sensor 10 operates over a frequency band from 76.5 GHz to 77.5 GHz. The RI radar waves are therefore emitted over the frequency range of 76.5 GHz to 77.5 GHz, corresponding to a wavelength range I1 of between 3.87 millimeters (mm) and 3.92 mm.

[0052] In another embodiment, if the radar sensor 10 operates at a radar frequency of 78.5 GHz with a frequency band of 5 GHz, the radar sensor 10 operates on a frequency band from 76 GHz to 81 GHz. In this case, the RI radar waves are thus emitted on the frequency range of 76 GHz to 81 GHz, corresponding to a wavelength range I1 of wavelengths between 3.701 mm and 3.945 mm.

[0053] The radar sensor 10 is configured to scan the external environment of the motor vehicle 1, by means of the emission of radar waves RI, R2.

[0054] For this purpose, as shown in [Fig. 3], the radar sensor 10 comprises:

[0055] - at least one transmitting antenna 100 configured to emit first waves RI radar and second-wave R2 radar, and

[0056] - at least two receiving antennas 101 configured to receive radar waves (not shown) received by reflection from the external environment of the motor vehicle 1.

[0057] In practice, the radar sensor 10 also includes at least one transmitter 103 configured to generate the radar waves RI, R2. It also includes at least one receiver 104 configured to process the radar waves received in return.

[0058] In one embodiment, a single electronic component can be used to implement both the transmission and reception functions. The lighting device then comprises, in this case, one or more transmitter / receivers (also called "transceivers" according to the commonly used Anglo-Saxon term).

[0059] In practice, the transmitter 103 generates radar waves RI, R2 which are subsequently emitted by the transmitting antenna 100. When these waves encounter an object (not visible in the figures) in the external environment of the motor vehicle 1, they are reflected by that object. The reflected radar waves are transmitted back to the radar sensor 10. These are the radar waves received by the receiving antennas 101. They correspond to the radar waves retransmitted towards the radar sensor 10.

[0060] In one embodiment, the radar waves RI, R2 and the radar waves received in return are radio frequency waves.

[0061] Alternatively (not shown), the radar sensor may comprise a plurality of transmitters and a plurality of receivers.

[0062] In practice, the transmitting antenna 100 is configured to transmit the radar waves RI, R2 generated by the transmitter 103. The receiving antennas 101 are configured to receive the returning radar waves and transmit them to the receiver 104, which then processes them. There is a phase shift between the radar waves received by the receiving antennas 101, which allows the position of the object in question to be deduced relative to the motor vehicle 1, an object located in the external environment of the motor vehicle 1.

[0063] In the following, the transmitting antenna 100 and the receiving antennas 101 are denoted "radar antennas 100, 101", it being understood that, in the minimum configuration, the radar sensor 10 comprises one transmitting antenna 100 and two receiving antennas 101.

[0064] In practice here, the radar antennas 100, 101 are offset from the other elements of the radar sensor 10 (shown in dotted lines in [Fig. 2] to illustrate this "offset" characteristic). The transmitter 103 and the receiver 104 are then arranged on a printed circuit board 105. The printed circuit board 105 is then connected to the radar antennas 100, 101 but positioned at a distance from these antennas 100, 101 (the radar antennas 100, 101 are therefore offset from the printed circuit board 105). The printed circuit board is, for example, a rigid printed circuit board also called a PCBA (for "Printed Circuit Board Assembly" according to the commonly used Anglo-Saxon terminology). Alternatively, the printed circuit board can be a flexible printed circuit board (or "Flexboard" according to the commonly used Anglo-Saxon terminology).

[0065] The radar sensor 10 further includes an electronic control unit 106 configured to control the transmitter 103 and the receiver 104.

[0066] In practice, the radar antennas 100, 101 are, for example, so-called "patch antennas" (or "patch antennas" according to the commonly used Anglo-Saxon terminology). Alternatively, the radar antennas may be so-called "slot antennas" (or "slot antennas" according to the commonly used Anglo-Saxon terminology).

[0067] Preferably here, the radar antennas 100, 101 are in the form of a first metallic mesh (or “mesh” according to the original Anglo-Saxon term).

[0068] Figure 4 schematically represents the radar antenna 100, 101 according to the present invention. The radar antenna 100, 101 therefore comprises a first metallic mesh. This first metallic mesh is, for example, formed in the XY plane (orthogonal to the horizontal plane of the motor vehicle 1). This first metallic mesh is conductive.

[0069] Advantageously, the radar antenna 100 is made so as to obtain a horizontal polarization direction of the wave (i.e. in the horizontal plane of the motor vehicle 1).

[0070] As can be seen in [Fig. 4], the radar antenna 100, 101 here has an overall zigzag shape. This overall shape optimizes the antenna's performance. Alternatively, any other shape may be used.

[0071] The length of the radar antenna 100, 101, along the X direction, is on the order of a few centimeters (cm). For example, this length is between 3 and 6 cm, preferably on the order of 5 cm.

[0072] In this overall zigzag shape, the first metal mesh is visible, but its arrangement and dimensions make it almost transparent to the naked eye. It comprises 110 metal strips arranged to form a metal grid.

[0073] Advantageously, these metallic strips 110 are micrometric, that is to say, they form metallic patterns of micrometric dimensions. In other words, by defining a first mesh size dl (visible in [Fig. 5]), that is to say, a dimension of a pattern repeated in the first metallic mesh, this first The mesh size dl is micrometric. A micrometric metallic grid is thus formed. These micrometric dimensions are particularly advantageous because the formed metallic grid is barely visible to the naked eye. Furthermore, such a structure allows for very good performance of the radar antenna 100, 101. In addition, the first metallic mesh does not affect the performance of a lighting or signaling device that emits a light beam passing through this first metallic mesh. Finally, such dimensions, which are not too small, facilitate the manufacture of the radar antenna 100, 101.

[0074] Preferably, the width b (visible in [Fig. 5]), in the XY plane, of each metal strip 110 is on the order of a few tens to hundreds of nanometers (nm). Each metal strip 110 has a thickness (along the Z-axis) ranging from a few nanometers to a few micrometers. This thickness depends in practice on the manufacturing process used to produce the first metal mesh. Preferably, this thickness is less than 20 micrometers (pm). Even more preferably, this thickness is less than 10 pm, or even less than 8 pm. These thickness values ​​are particularly easy to obtain by screen printing. This process is notably inexpensive and simple to implement.

[0075] Within the scope of the present invention, the thickness of each metal strip 110 can also be between 200 nm and 2 pm. These thickness values ​​are obtained, for example, by lithography. This makes it possible to obtain very thin strips for each metal strip 110, ensuring transparency of the luminous module 5 described below.

[0076] The first metallic mesh comprises, for example, copper. Alternatively, it may comprise silver, platinum, aluminum, or nickel. In practice, the metallic strips are formed, for example, by nanolithography.

[0077] In practice, each radar antenna 100, 101 is, for example, formed by cutting, here in a zigzag shape, from a plate comprising the first metal mesh. Alternatively, the metal strips 110 can be selectively deposited so as to form the first metal mesh and the overall shape of each radar antenna 100, 101. Alternatively still, the metal strips 110 can be produced by engraving the different metal patterns side by side.

[0078] As can be seen in particular in [Fig. 1], the light module 5 is intended to be positioned in the path of a light beam coming, for example, from a lighting device. However, given the regular pattern of the first metallic mesh forming each radar antenna 100, 101 and the dimensions of the first metallic mesh, this first metallic mesh forms a diffraction grating for the light beam passing through the radar antenna 100, 101.

[0079] In order to limit or even completely eliminate higher orders of diffraction, the first mesh size dl is advantageously chosen in the present invention. More particularly, the first mesh size dl is advantageously determined so as to allow only 0th-order propagation (so as not to observe diffraction phenomena after the propagation of the light beam L; through the radar antenna 100, 101 in the form of the first metallic mesh). In other words, the first mesh size dl is predefined and determined so as to prevent diffraction phenomena during the propagation of a light beam L; through the light module 5.

[0080] Fig. 5 represents a cross-sectional view of the radar antenna 100, 101 shown in Fig. 4, along a section plane AA.

[0081] As can be seen in Figure 5, three characteristic dimensions are introduced to define the first metallic mesh of the radar antenna 100, 101: the width b of each metallic strip 110, a spacing a between two adjacent metallic strips 110 and the first mesh pitch dl (corresponding to the dimension of the repeated pattern to form the metallic grid structure of the radar antenna 100). By definition, the following relationship is observed between these three characteristic dimensions: dl = b + a.

[0082] As will be described later, each radar antenna 100, 101 is in practice overmolded or encapsulated in the intermediate layer 30. This intermediate layer 30 has a refractive index denoted n2. The refractive index n2 of the intermediate layer 30 is less than 2. Preferably, it is between 1.4 and 1.95. It should be noted here that the intermediate layer 30 includes the radar antennas 100, 101 (and the parasitic antennas 200, 201 described below) of the radar sensor 10 and that the other elements of this radar sensor 10 are offset from the radar antennas 100, 101 and the parasitic antennas 200, 201 (in other words, the other elements of the radar sensor 10 are positioned outside the intermediate layer 30).

[0083] It is noted here that the light beam L; propagates in a first medium with refractive index n3, then is incident on the intermediate layer 30 comprising the radar antenna 100. At the level of this intermediate layer 30, the angle of incidence is noted 0;. It should be noted here that the first medium corresponds, for example, in the case of [Fig.2], to the conductive layer 40.

[0084] In practice, by arrangement of the different elements (lighting device, luminous device 5A) in the motor vehicle 1, this angle of incidence 0; is, in absolute value, less than 60 degrees (°).

[0085] Thus, by applying the classical formula for transmission networks, and in order to obtain only zero-order propagation (therefore no phenomena (diffraction), the first mesh step dl must satisfy the following inequality (X here corresponds to the wavelength of the light beam L;):

[0086] dii--A—

[0087] In other words, the first mesh step dl is less than a value depending on the wavelength X of the light beam L;, the refractive index n2 of the intermediate layer 30, the refractive index n3 of the first medium (here the conducting layer 40) and the angle of incidence 0; of the light beam L; at the level of the intermediate layer 30.

[0088] In practice in the present invention, the first mesh size dl is less than a few hundred nanometers, for example less than 500 nanometers, in order to prevent the first metallic mesh of the radar antenna 100, 101 from behaving like a diffraction grating for a light beam L; (corresponding to a wavelength of the visible spectrum).

[0089] For example, considering a light beam L; with a wavelength of the order of 550 nm, the first mesh step dl is less than 230 nm in order to avoid the presence of diffraction phenomena (which would be due to the regular metallic mesh forming the radar antenna 100, 101).

[0090] In practice, if the light beam were to pass through several layers before the first medium with refractive index n3, it would be possible to modify the inequality presented above by applying, for all the layers traversed before the first medium, a succession of Snell's law of refraction to express the angle of incidence θ on the intermediate layer. The resulting expression would then be combined with the classical formula for transmission gratings to obtain the inequality concerning the first mesh size dl. In general, the first mesh size dl is less than a quantity that depends on the wavelength X of the light beam L, the refractive indices of the different layers traversed, and the angle of incidence of the light beam L on the light modulus.

[0091] As shown in [Fig.2], the radar sensor 10 also includes at least two parasitic antennas 200, 201. As can be seen in particular in [Fig.2], the parasitic antennas 200, 201 are positioned between the radar antennas 100, 101.

[0092] In practice, a parasitic antenna 200, 201 is spaced from an adjacent radar antenna 100, 101 by a distance on the order of the wavelength X of the light beam L;. Furthermore, two adjacent parasitic antennas 200, 201 are spaced from each other by a distance on the order of half the wavelength X of the light beam L;. This positioning ensures proper operation of the radar sensor 10.

[0093] The parasitic antennas 200, 201 resemble, in structure, the radar antennas 100, 101 but have one major difference in that these parasitic antennas 200, 201 are not electrically connected. In other words, the parasitic antennas 200, 201 are not connected to a power supply that would allow the flow of a "direct" electric current, i.e., from a power supply, in these parasitic antennas 200, 201 (however, as indicated below, an induced electric current may flow in these parasitic antennas 200, 201).

[0094] Conventionally, with regard to the operation of these parasitic antennas 200, 201, an electric current flowing in the radar antennas 100, 101 produces an electromagnetic field that induces electric currents in the parasitic antennas 200, 201. The current induced in these parasitic antennas 200, 201 in turn produces other radiated electromagnetic fields, which will induce other electric currents (including in the radar antennas 100, 101). The electromagnetic field radiated by the radar sensor 10 then corresponds to the sum of the fields radiated by each of the radar antennas 100, 101 and parasitic antennas 200, 201 in a given direction.

[0095] The parasitic antennas 200, 201 are, for example, so-called "dot" antennas. Alternatively, the parasitic antennas 200, 201 may be so-called "slit" antennas.

[0096] Preferably, as was the case for the radar antennas 100, 101 described previously, the parasitic antennas 200, 201 take the form of a second metallic mesh. This second metallic mesh is, for example, formed in the XY plane (orthogonal to the horizontal plane of the motor vehicle 1). Advantageously, the second metallic mesh is arranged to obtain a horizontal polarization direction of the wave (i.e., in the horizontal plane of the motor vehicle 1).

[0097] The length of each parasitic antenna 200, 201, along the X direction, is on the order of a few centimeters (cm). For example, this length is between 3 and 6 cm, preferably on the order of 5 cm.

[0098] As in the case of the radar antennas 100, 101 described previously, this second metallic mesh is visible. It also comprises metallic strips arranged to form a metallic grid. Where a regular metallic grid is formed, the second metallic mesh has characteristics similar to those described for the radar antennas 100, 101 previously (they are therefore not described in detail again here).

[0099] Essentially, the metal strips of this second metal mesh are, for example, micrometric, that is to say, with a second mesh size d2 having a micrometric dimension. Preferably, the first mesh size The mesh size dl of each radar antenna 100, 101 is less than the second mesh size d2 of the second metal mesh of each parasitic antenna 200, 201. In other words, the first metal mesh of each radar antenna 100, 101 has a higher mesh density than another mesh density of the second mesh of each parasitic antenna 200, 201. This makes it easier to manufacture the second metal mesh (because the parasitic antennas have fewer constraints to respect than the radar antennas).

[0100] Here, the mesh density of the first metallic mesh of each radar antenna 100, 101 is for example at least 10 times greater than the other mesh density of the second metallic mesh of each parasitic antenna 200, 201.

[0101] The width, in the XY plane, of each metal strip of the second metal mesh is on the order of a few tens to hundreds of nanometers. Each metal strip of this second metal mesh has a thickness (along the Z-axis) ranging from a few nanometers to a few micrometers. This thickness depends in practice on the manufacturing process used to produce this second metal mesh. Preferably, this thickness is less than 20 micrometers (µm). Even more preferably, this thickness is less than 10 µm, or even less than 8 µm. These thickness values ​​are particularly easy to obtain by screen printing. This process is notably inexpensive and simple to implement.

[0102] In the context of the present invention, the thickness of each metal strip of the second metal mesh is between 200 nm and 2 pm. These thickness values ​​are obtained, for example, by lithography. This makes it possible to obtain very thin thicknesses for each metal strip of the second metal mesh, guaranteeing transparency of the lighting device according to the invention.

[0103] The second metallic mesh comprises, for example, copper. Alternatively, it may comprise silver, platinum, aluminum, or nickel. In practice, the metallic strips are formed, for example, by nanolithography.

[0104] In practice, the second metal mesh is formed, for example, by cutting from a plate comprising the metal strips. Alternatively, the metal strips can be selectively deposited to form the second metal mesh. As a further alternative, the metal strips can be produced by engraving the different metal patterns side by side.

[0105] Alternatively, for the case of the parasitic antennas 200, 201 (which are not electrically connected), the second metallic mesh can be irregular. In other words, the metallic strips can have random shapes. Put another way, no periodicity of patterns is observed in this irregular structure. The use of this irregular structure for the parasitic antennas 200, 201 allows to avoid diffraction phenomena for the light beam coming from the signaling and / or lighting device.

[0106] Furthermore, and as discussed later with regard to the conductive layer, the second metallic mesh can also be adapted to perform a defrosting function, for example when an electric current passes through it. This is particularly advantageous when the lighting device is exposed to variable weather conditions (rain, snow, ice).

[0107] As can be seen in [Fig.2], the light module 5 also includes the protective panel 20.

[0108] This protective panel 20 corresponds, for example, here to an external window of the motor vehicle 1. The protective panel 20 forms, for example, part of the lighting device 5A which corresponds, for example, to a headlight or a rear light of the motor vehicle 1. In practice, the protective panel 20 forms an outer layer of the lighting module 5, that is to say, a layer which is in direct contact with the external environment of the motor vehicle 1.

[0109] Whatever the use considered, the protective panel 20 is particularly suitable for protecting radar antennas 100, 101 and parasitic antennas 200, 201.

[0110] In the example shown in [Fig.2], the protective panel 20 is positioned opposite the radar antennas 100, 101 and the parasitic antennas 200, 201. The protective panel 20 has a refractive index ni on the wavelength scale / ., of the range Al of wavelengths introduced previously.

[0111] Here, the protective panel 20 is in the form of a layer and comprises an outer face 21 and an inner face 22, opposite the outer face 21. The outer face 21 is here directly in contact with the external environment of the motor vehicle 1.

[0112] Advantageously, the protective panel 20 comprises a material transparent to wavelengths I, of radar waves RI emitted by the radar antenna 100 and transparent to wavelength X of the light beam L from a lighting or signaling device. In other words, the protective panel 20 comprises a material transparent to radar waves and to a light beam with a wavelength in the visible spectrum.

[0113] Here, the protective panel 20 comprises a polymer material. Preferably, this is polycarbonate (PC). Alternatively, the protective panel may comprise poly(methyl methacrylate) (PMMA). Alternatively still, the protective panel may comprise polyurethane (PUR).

[0114] In order to comply with dimensioning requirements associated with the integration of the lighting device 5A into the motor vehicle 1, a thickness ei (i.e. A dimension along the Z-axis of the protective panel 20 is less than 5 millimeters (mm). Preferably, this thickness ei is between 300 µm and 4 mm.

[0115] The radar sensor 10 (and more specifically the radar antenna 100) emits the first RI radar waves, which propagate towards the protective panel 20. Due to the differences in refractive indices and the interfaces formed by the inner face 22 and the outer face 21 of the protective panel 20, the first RI radar waves are partially reflected. The reflection of some of the first RI radar waves by the inner face 22 of the protective panel 20 forms second reflected radar waves R22, which propagate towards the intermediate layer 30. Furthermore, the reflection of some of the first RI radar waves by the outer face 21 of the protective panel 20 forms third reflected radar waves R21, which also propagate towards the intermediate layer 30.

[0116] Advantageously, according to the invention, the thickness ei of the protective panel 20 is optimized so that the second reflected radar waves R22 and the third reflected radar waves R21 are out of phase. In other words, the thickness ei of the protective panel 20 is determined here so as to obtain destructive interference between the second reflected radar waves R22 and the third reflected radar waves R21.

[0117] In practice, the thickness ei is chosen so as to introduce a phase shift of ir / 2 between the second reflected radar waves R22 and the third reflected radar waves R21.

[0118] This condition for determining the thickness ei of the protective panel 20 makes it possible to reduce or even eliminate the reflected radar waves R21, R22 on the protective panel 20, which would degrade the efficiency (and in particular the range) of the radar sensor 10. This optimization of the thickness ei of the protective panel 20 improves the signal-to-noise ratio of the radar sensor 10 because the parasitic reflections are eliminated (or greatly reduced so that they do not reduce the signal-to-noise ratio associated with the radar sensor). The performance of the radar sensor 10 is therefore considerably improved.

[0119] As can be seen in [Fig. 2], the light module 5 also includes the intermediate layer 30. This intermediate layer 30 comprises a transparent flexible material. As with the protective panel 20, the intermediate layer 30 is transparent to wavelengths I, R2, of the radar waves emitted by the radar antenna 100 and transparent to the wavelength of a light beam from a lighting or signaling device. In this description, the term "flexible material" means a material that has the ability to deform (for example, to bend) without breaking or cracking. Thanks to this characteristic flexible, the intermediate layer is not necessarily contained in a plane but can have a curved shape (depending on the position in which it is placed).

[0120] Preferably, the intermediate layer 30 comprises a polymer material. For example, polyethylene terephthalate (PET). Alternatively, the intermediate layer 30 may comprise silicone.

[0121] In practice, the intermediate layer 30 is, for example, bonded to the protective panel 20. The adhesive used here is, for example, an optically clear adhesive (or OCA for "Optically Clear Adhesive," according to the commonly used Anglo-Saxon acronym). Alternatively, the intermediate layer 30 can be laminated to the protective panel 20.

[0122] As previously stated, this intermediate layer 30 includes the radar antennas 100, 101 and the parasitic antennas 200, 201. Here, the intermediate layer 30 forms, for example, a support substrate for the radar antennas 100, 101 and the parasitic antennas 200, 201 (in particular for the first metallic mesh forming the radar antennas 100, 101 and for the second metallic mesh forming the parasitic antennas 200, 201).

[0123] According to the example shown in [Fig.2], the intermediate layer 30 comprises a first part 34 and a second part 35. The first part 34 and the second part 35 of the intermediate layer 30 are arranged so as to sandwich the radar antennas 100, 101 and the parasitic antennas 200, 201. The second part 35 of the intermediate layer 30 forms, for example, a support substrate for the radar antennas 100, 101 and the parasitic antennas 200, 201 (in particular for the first metallic mesh forming the radar antennas 100, 101 and for the second metallic mesh forming the parasitic antennas 200, 201). In other words, in this example, radar antennas 100, 101 and parasitic antennas 200, 201 are encapsulated in the intermediate layer 30.This positioning example is particularly advantageous because it allows for an assembly in which the radar antennas 100, 101 and the parasitic antennas 200, 201 are protected from the outside (in particular from shocks).

[0124] Here, the first part 34 of the intermediate layer 30 is positioned between, on the one hand, the protective panel 20 and, on the other hand, the radar antennas 100, 101 and the parasitic antennas 200, 201. In practice, the first part 34 of the intermediate layer 30 is, for example, glued to the protective panel 20. Alternatively, the first part 34 can be laminated onto the protective panel 20.

[0125] This example introduces a symmetry advantage in the structure of the light device 5A, thereby optimizing the performance of the radar sensor 10 and the efficiency of the light module 5.

[0126] In an alternative (not shown), the radar antennas 100, 101 and the parasitic antennas 200, 201 can be positioned on a first face 31 of the intermediate layer 30. In other words, in this alternative, the radar antennas 100, 101 and the parasitic antennas 200, 201 are positioned directly between the protective panel 20 and the intermediate layer 30.

[0127] In this case, the radar antennas 100, 101 and the parasitic antennas 200, 201 are, for example, glued to the first face 31 of the intermediate layer 30. Alternatively, the radar antennas 100, 101 and the parasitic antennas 200, 201 can be overmolded onto the first face 31 of the intermediate layer 30. This placement of the radar antennas 100, 101 and the parasitic antennas 200, 201 on the first face 31 of the intermediate layer 30 is particularly easy and inexpensive to implement.

[0128] Advantageously according to the invention, the light device 5A of the light module 5 also includes the conductive layer 40. This conductive layer 40 is arranged in such a way that the intermediate layer 30 is positioned between the protective panel 20 and the conductive layer 40.

[0129] The conductive layer 40 is here adapted to form in part a ground plane of the radar sensor 10 (more particularly of the radar antennas 100, 101 included in the radar sensor 10). In other words, this conductive layer 40 forms a reflective surface for radar waves and has dimensions (of the elements forming this conductive layer 40) large compared to the wavelength λ of the radar waves.

[0130] As shown in [Fig.2], the radar sensor 10 (and more particularly the radar antenna 100) emits the second radar waves R2, which propagate towards the conductive layer 40. Given the ground plane functionality formed by the conductive layer 40, the second radar waves R2 are partly reflected by a first face 41 of the conductive layer 40 so as to form other reflected radar waves R41, which propagate towards the intermediate layer 30.

[0131] The first face 41 of the conductive layer 40 is oriented towards the radar antenna 100. In other words, the first face 41 of the conductive layer 40 is the face of the conductive layer 40 that is closest to the radar antenna 100. The radar antenna 100 is positioned at a distance e2 from the first face 41 of the conductive layer 40. According to the example shown in [Fig. 2], the distance e2 corresponds to the thickness of the second part 35 of the intermediate layer 30. Alternatively (not shown), if the radar antenna is positioned on the first face 31 of the intermediate layer 30, the distance e2 corresponds to the thickness of the intermediate layer 30.

[0132] Advantageously, according to the invention, this distance e2 is optimized so that the first RI radar waves and the other reflected radar waves R41 are in phase. In other words, the distance e2 between the radar antenna 100 and the conductive layer 40 is determined here so as to obtain constructive interference between the first RI radar waves and the other reflected radar waves R41.

[0133] In practice, the distance e2 is chosen so as to introduce a phase shift of ir between the first radar waves RI and the other reflected radar waves R41.

[0134] This condition for determining the distance e2 between the radar antenna 100 and the conductive layer 40 then makes it possible to optimize the transmission of radar waves in the luminous device 5A of the luminous module 5. This optimization of the distance e2 between the radar antenna 100 and the conductive layer 40 also makes it possible to improve the signal-to-noise ratio of the radar sensor 10 and therefore the performance of the radar sensor 10.

[0135] In practice, in order to obtain this condition of constructive interference, the distance e2 is proportional to one quarter of the wavelength / ., of the radar waves RI, R2 emitted by the radar antenna 100 or to half of this wavelength Xr.

[0136] For radar frequencies between, for example, 76 and 81 GHz (corresponding to a wavelength of RI, R2 radar waves between 3.7 and 4 mm), the distance e2 is on the order of a few millimeters, more particularly between 0.9 and 4 mm for refractive indices n2 of the intermediate layer 30 between 1.4 and 1.95 (the radar antenna 100 being overmolded or encapsulated in this intermediate layer 30).

[0137] The conductive layer 40 has a thickness of a few micrometers. Preferably, this thickness is less than 5 pm. Even more preferably, the thickness of the conductive layer 40 is between 200 nm and 2 pm. Generally, the intermediate layer 30 is thick enough to withstand the mechanical stresses that the light-emitting device 5A of the light module 5 might experience. It is also thin enough to retain its supple and flexible nature. Its thickness is therefore determined by satisfying this compromise.

[0138] In practice, the conductive layer 40 comprises a material transparent to the wavelength of the light beam from a lighting or signaling device. For example, the conductive layer 40 comprises a material transparent to wavelengths in the visible spectrum while retaining its conductive character.

[0139] In a first embodiment of the conductive layer 40 (shown in [Fig. 2]), the latter comprises indium tin oxide (or ITO for "Indium tin oxide” according to the original Anglo-Saxon name). In this example, the conductive layer 40 is then formed of a block.

[0140] In a second embodiment of the conductive layer 40, shown for example in [Fig. 6], the conductive layer 40 comprises a third metallic mesh 40a. This third metallic mesh 40a is, for example, formed in the XY plane (orthogonal to the horizontal plane of the motor vehicle 1). Advantageously, the third metallic mesh 40a is formed parallel to a direction of radar polarization. As can be seen in [Fig. 6], the conductive layer 40 here comprises a substrate 40b forming a support for the third metallic mesh 40a.

[0141] The length of the third metallic mesh 40a, along the X direction, is on the order of a few centimeters. For example, this length is at least greater than the length of the radar antenna 100.

[0142] As in the case of the radar antennas 100, 101 described previously, this third metallic mesh 40a is visible. It also comprises metallic strips arranged to form a metallic grid. Where a regular metallic grid is formed, the third metallic mesh 40a has characteristics similar to those described for the radar antennas 100, 101 previously (they are therefore not described in detail again here).

[0143] Essentially, the metallic strips of this third metallic mesh 40a are, for example, micrometric, that is to say, with a mesh size of one micrometer. Preferably, the first mesh size of the first metallic mesh of the radar antennas 100, 101 is smaller than the third mesh size of the third metallic mesh 40a of the conductive layer 40. This makes it easier to manufacture this third metallic mesh 40a (because the conductive layer 40 has fewer constraints to meet than the radar antennas 100, 101).

[0144] The width, in the XY plane, of each metal strip of this third metal mesh 40a is on the order of a few tens to hundreds of nanometers. Each metal strip of this third metal mesh 40a has a thickness (along the Z-axis) ranging from a few nanometers to a few micrometers. This thickness depends in practice on the manufacturing process used to produce this third metal mesh. Preferably, this thickness is less than 20 micrometers (pm). Even more preferably, this thickness is less than 10 pm, or even less than 8 pm. These thickness values ​​are particularly easy to obtain by screen printing. This process is notably inexpensive and simple to implement.

[0145] In the context of the present invention, the thickness of each metal strip of this third metal mesh 40a is between 200 nm and 2 pm. These thickness values ​​are obtained, for example, by lithography. This makes it possible to obtain very thin thicknesses for each metal strip of this third metal mesh, guaranteeing transparency of the light module according to the invention.

[0146] The third metallic mesh 40a comprises, for example, copper. Alternatively, it may comprise silver, platinum, aluminum, or nickel. In practice, the metallic strips are formed, for example, by nanolithography.

[0147] In practice, the third metal mesh 40a is, for example, formed by cutting from a plate comprising the metal strips. Alternatively, the metal strips can be selectively deposited to form the other metal mesh. As a further alternative, the metal strips can be produced by engraving the different metal patterns side by side.

[0148] Alternatively, for the conductive layer 40, whose important characteristic is to form a ground plane for the radar antennas 100, 101 (and thus a reflective surface for the RI, R2 radar waves), the third metallic mesh 40a can be irregular. In other words, the metallic bands can have random shapes. Put another way, no periodicity of patterns is observed in this irregular structure. The use of this irregular structure makes it possible to avoid diffraction phenomena for the light beam from signaling and / or lighting devices.

[0149] Thus, the use of the conductive layer 40 optimizes the transmission of radar waves in the light module 5, thereby improving the performance of the radar sensor 10. Furthermore, this conductive layer 40 forms a ground plane for the radar sensor 10 (and more particularly for the radar antennas 100, 101), necessary for the proper functioning of this radar sensor 10 (making it possible in particular to create a potential difference which is the origin of the generation of radar waves).

[0150] Furthermore, the conductive layer 40 also has the advantage of being able to behave as a heating element directly integrated into the light device 5A of the light module 5. This is particularly advantageous because, in addition to improving the performance of the radar sensor thanks to the positioning of the conductive layer 40 relative to this radar sensor 10, the conductive layer behaving as a heating element will prevent the deposition of water or frost in front of the radar sensor (these deposits altering the detection functionalities of the radar sensor because the water droplets also disrupt the radar sensor, the water partially absorbing the radar waves used for detection).

[0151] In this regard, optionally (represented only in the example of [Fig. 7]), the luminous device of the luminous module may include a layer thermally conductive, positioned on a second face 42 of the conductive layer 40 (i.e., on the face of the conductive layer 40 furthest from the radar antenna 100, 101). This thermally conductive layer improves the homogeneity of the heating effects from the conductive layer 40.

[0152] In practice, this thermally conductive layer comprises indium tin oxide. Alternatively, the thermally conductive layer may comprise carbon nanotubes. Alternatively, this thermally conductive layer may comprise graphene.

[0153] Furthermore, in order to ensure transparency properties for the lighting device, the thermally conductive layer comprises a material transparent to the wavelength X of a light beam L from a lighting or signaling device. In other words, the thermally conductive layer comprises a material transparent to a light beam with a wavelength in the visible spectrum.

[0154] In the case of a thermally conductive layer comprising indium tin oxide, a light transmission rate for the visible spectrum is greater than 85%, guaranteeing the transparency properties mentioned above.

[0155] The thermally conductive layer has a thickness on the order of a few hundred micrometers. For example, this thickness is between 40 and 200 pm.

[0156] In practice, the thermally conductive layer is, for example, bonded to the conductive layer. The adhesive used here is, for example, an optically transparent adhesive (or OCA). Alternatively, the thermally conductive layer can be laminated onto the conductive layer.

[0157] As shown in [Fig.2], the light module 5 also includes the light source 70. This light source 70 is adapted to enable the implementation of a lighting function or a signaling function.

[0158] The light source 70 is positioned opposite the second face 42 of the conductive layer 40. The light source 70 is, for example, positioned at a distance of less than 50 centimeters (cm) from the nearest face of the light-emitting device (here, for example, the second face 42 of the conductive layer 40). Preferably, this distance is less than 20 cm.

[0159] In the present invention, the light source 70 is adapted to project a cutoff beam so as to perform a lighting function. Preferably, the light source comprises, for example, a collector in the form of an elliptical reflector, and a lens. This lens is arranged to project an image of an edge of the collector so as to form the cutoff in the light beam.

[0160] In practice, the light source 70 is for example of the semiconductor type, such as in particular a light-emitting diode.

[0161] The light source 70 then emits the light beam L, enabling the implementation of the lighting and / or signaling functions. This light beam L, emerging from the light source 70, propagates through the lighting device 5A. More specifically, the light beam L propagates from the conductive layer 40 towards the protective panel 20.

[0162] The light beam L; has an angular aperture a which allows a propagation field of this light beam L; to be defined. In practice, this angular aperture a extends between -4 and +4 degrees (corresponding to a total angular aperture of 8 degrees).

[0163] Advantageously, according to the present invention, the parasitic antennas 200, 201 are positioned in the propagation field of the light beam L;. In other words, the light beam L; propagates through the parasitic antennas 200, 201.

[0164] Moreover, the radar antennas 100, 101 are located outside the propagation field of the light beam L;.

[0165] These arrangements are particularly advantageous because the parasitic antennas, with their lower mesh density, do not impede the propagation of the light beam L; (in order to implement the lighting and / or signaling functions). Indeed, the lower mesh density ensures better optical transparency (i.e., to the visible spectrum) of the lighting device compared to the parts equipped with the radar antennas. The light beam L; then propagates through these parts with this improved optical transparency, thus guaranteeing the effective implementation of the lighting and / or signaling functions.

[0166] In other words, the electrically connected conductive elements (here, the radar antennas 100, 101) are positioned outside the propagation field of the light beam L, so as not to interfere with the propagation of this light beam. This ensures, in particular, that the lighting and signaling functions are clearly visible from outside the motor vehicle 1 to users outside the vehicle. Specifically, this arrangement prevents any potential diffraction phenomena during the propagation of the light beam L.

[0167] In practice, for example when the light module is integrated into a headlight of the motor vehicle 1, the light module 5 forms, for example, a low-beam or dipped beam (or "low-beam" according to the commonly used Anglo-Saxon term) with a horizontal cut-off equipped with a kink (or "kink" according to the Anglo-Saxon term). The parasitic antennas and the propagation field of the light beam are then arranged to be positioned in relation to this bump. This notably allows for compliance with the various regulatory requirements regarding signaling in a motor vehicle.

[0168] Fig. 6 represents a cross-sectional view of a light module 6 according to a second embodiment of the invention.

[0169] In this second embodiment, the light device 6A of the light module 6 also includes another protective panel 50. The conductive layer 40 is here situated between the intermediate layer 30 and the other protective panel 50.

[0170] This other protective panel 50 is introduced here to give structural symmetry to the lighting device 6A of the lighting module 6. This structural symmetry makes it possible to give stability to the lighting device, thus ensuring efficient operation.

[0171] For this purpose, the other protective panel 50 has structural characteristics similar to the protective panel described above. In particular, the other protective panel 50 has a thickness similar to that of the protective panel 20. By "similar," it is understood here that a difference of less than 5% can be observed between the thickness of the other protective panel and the thickness of the protective panel.

[0172] In order to comply with the dimensioning requirements associated with the integration of the lighting device 6A into the motor vehicle 1, the thickness of the other protective panel 50 is less than 5 mm. Preferably, this thickness is between 1.8 and 4 mm.

[0173] Here, the other protective panel 50 comprises a polymer material. Preferably, this is polycarbonate (PC). Alternatively, the other protective panel may comprise poly(methyl methacrylate) (PMMA). Alternatively still, the other protective panel may comprise polyurethane (PUR).

[0174] Advantageously, the other protective panel 50 comprises a material transparent to the wavelength of a light beam from a lighting or signaling device. It is not necessary for this material to be transparent to the wavelengths of radar waves emitted by the radar sensor 10, since these radar waves do not propagate through this other protective panel 50.

[0175] Although not shown in the figures, the lighting device 5A; 7A shown in figures 2 and 7 may of course include such another protective panel.

[0176] Optionally (not shown) in this second embodiment, the lighting device may also include the thermally modified layer conductive. This thermally conductive layer is positioned here between the conductive layer 40 and the other protective panel 50.

[0177] Fig. 7 represents a cross-sectional view of a light module 7 according to a third embodiment of the invention.

[0178] In this embodiment, the conductive layer 40 has a first part 44 and a second part 45. The first part 44 of the conductive layer 40 is positioned opposite the radar antennas 100, 101. The second part 45 of the conductive layer 40 is positioned opposite the portion of the intermediate layer 30 housing the parasitic antennas 200, 201.

[0179] In practice, the distinction between the first part 44 and the second part 45 of the conductive layer 40 is based on a difference in surface resistance (or "sheet resistance" according to the commonly used Anglo-Saxon term) between these two parts.

[0180] More particularly, in order to ensure the ground plane function for the radar antennas 100, 101, the surface resistance of the first part 44 of the conductive layer 40 is greater than the surface resistance of the second part 45 of the conductive layer 40.

[0181] Preferably, the surface resistance of the second part 45 of the conductive layer 40 is ten times smaller than the surface resistance of the first part 44 of the conductive layer 40.

[0182] Thus, this difference in surface resistance ensures that, with respect to the radar antennas 100, 101, the conductive layer 40 behaves as a ground plane, but that outside this area with respect to the radar antennas (in particular with respect to the parasitic antennas 200, 201), the conductive layer 40 can behave as a heating element. In other words, the formation of the conductive layer in two parts with different surface resistances (and with a difference of an order of magnitude) makes it possible to decouple the two functions (ground plane and heating) but to implement them nonetheless within the same conductive layer.

[0183] This is particularly advantageous because the proper functioning of the radar antennas 100, 101 is guaranteed (the potential difference necessary to generate the radar waves is obtained thanks to the first part of the conductive layer) and, at the same time, the efficiency of the radar sensor is also guaranteed because the second part of the conductive layer protects the light-emitting device from the elements. Indeed, thanks to the heating function of the second part of the conductive layer, water droplets, which would be due to rain, fog, snow, or frost, do not impede the proper functioning of the radar sensor. The second part of the conductive layer thus forms a heat diffuser.

[0184] Thanks to the two-part conductive layer according to the present invention, the radar (with the generation of radar waves) and heating functions can be implemented simultaneously in the lighting device.

[0185] In particular, the first part 44 and the second part 45 of the conductive layer 40 are not electrically connected. In other words, the first part 44 and the second part 45 of the conductive layer 40 are electrically driven independently.

[0186] For example, when the radar antennas 100, 101 are in operation, only the second part 45 has a heating function (so as to heat around the radar antennas but not opposite them).

[0187] In a defrosting mode, the radar antennas 100 are switched off while an electric current flows in the first part 44 and the second part 45 of the conductive layer 40 in order to implement the heating function.

[0188] In practice, each of the first part 44 and the second part 45 of the conductive layer 40 comprises, for example, indium tin oxide.

[0189] According to a preferred embodiment, each of the first part 44 and the second part 45 of the conductive layer 40 comprises a metallic mesh. The metallic mesh of the first part 44 of the conductive layer 40 is thus different from the metallic mesh of the second part 45 of the conductive layer 40. This difference is observed from the point of view of the mesh spacing and also from the point of view of the mesh pattern. This implementation is advantageous because the same deposition technology is used and makes it possible to obtain the two different functions, ground plane and heating. Moreover, this embodiment is particularly easy to implement and inexpensive.

[0190] In practice, the metallic mesh of the first part 44 of the conductive layer 40 is made parallel to a direction of polarization of the radar wave (so as to be able to reflect this radar wave).

[0191] In this case, and in order to comply with the constraint on the surface resistance, the mesh size of the first part 44 of the conductive layer 40 is less than the mesh size of the second part 45 of the conductive layer 40.

[0192] Alternatively, the second part 45 may comprise carbon nanotubes so as to provide the desired heating function. Alternatively, the second part 45 of the conductive layer 40 may comprise graphene.

[0193] Alternatively, it is possible that the first part 44 and the second part 45 of the conductive layer 40 are formed differently. For example, the first part 44 of the conductive layer 40 may comprise a metallic mesh while the second part 45 of the conductive layer 40 may comprise indium tin oxide or carbon nanotubes or graphene.

[0194] Optionally (shown in dashed lines in [Fig. 7]), the lighting device 7A may include the thermally conductive layer 60, positioned on the second face 42 of the conductive layer 40. This thermally conductive layer 60 improves the homogeneity of the heating effects from the conductive layer 40. In particular, this thermally conductive layer 60 will allow better heat diffusion from the second part 45 to the first part 44.

[0195] Although described in the context of this third embodiment example, this two-part conductive layer can of course be integrated into the embodiment examples of the light module described previously.

[0196] Regardless of the embodiment considered, the light module 5; 6; 7 is integrated into automotive equipment. The light module 5; 6; 7 according to the invention is then configured to implement lighting functions for the motor vehicle 1 using the light beam L; emitted by the light source 70. It is thus made possible to fulfill a lighting or aesthetic function, as well as an antenna function for a radar application.

[0197] In practice, as can be seen in [Fig.1], the light module 5; 6; 7 according to the invention can be integrated into the lighting device 3 and / or the signaling device 2 and / or in front of the lidar 4.

Claims

Demands

1. A light module (5; 6; 7) for a motor vehicle (1), said light module (5; 6; 7) comprising a light device (5A; 6A; 7A) configured to perform a lighting or signaling function of the motor vehicle (1), the light device (5A; 6A; 7A) comprising a stack including: a) a protective panel (20), b) an intermediate layer (30) comprising at least two radar antennas (100, 101) of a radar sensor (10) configured to emit and / or receive associated radar waves (RI), radar waves (RI) emitted by the radar antennas (100) propagating towards the protective panel (20), the intermediate layer (30) also comprising at least two parasitic antennas (200, 201) positioned between the two radar antennas (100, 101), the parasitic antennas (200, 201) not being electrically connected, each radar antenna (100, 101) comprising a first metallic mesh,each parasitic antenna (200, 201) comprising a second metallic mesh, the first metallic mesh having a mesh density greater than another mesh density of the second metallic mesh, and c) the conductive layer (40) adapted to partially form a ground plane for the radar antennas (100), the intermediate layer (30) being positioned between the protective panel (20) and the conductive layer (40), and the light module (5; 6; 7) also comprising a light source (70) adapted to enable the implementation of a lighting function, the light source (70) emitting a light beam (Li) propagating from the conductive layer (40) to the protective panel (20), the light beam (L;) having an angular opening (a) defining a propagation field, the parasitic antennas (200, 201) being positioned in the propagation field of the light beam (L;),the radar antennas (100) being located outside the propagation field of the light beam (L).,

2. Light module (5; 6; 7) according to claim 1, wherein the mesh density of the first metal mesh is at least 10 times greater than the other mesh density of the second metal mesh.

3. Light module (5; 6; 7) according to claim 1 or 2, wherein a parasitic antenna (200, 201) is spaced from an adjacent radar antenna (100) by a distance on the order of one wavelength (X) of the light beam (L;).

4. Light module (5; 6; 7) according to any one of claims 1 to 3, wherein two adjacent parasitic antennas (200, 201) are spaced apart from each other by a distance on the order of half a wavelength (X) of the light beam (L).

5. Light module (5; 6; 7) according to any one of claims 1 to 4, wherein the angular opening (a) of the light beam (L;) extends between -4 degrees and +4 degrees.

6. Light module (7) according to any one of claims 1 to 5, wherein the conductive layer (40) comprises a first part (44) and a second part (45), the second part (45) of the conductive layer (40) being positioned opposite the parasitic antennas (200, 201), the first part (44) of the conductive layer (40) being positioned opposite the radar antennas (100), the first part (44) of the conductive layer (40) having a surface resistance greater than another surface resistance of the second part (45) of the conductive layer (40).

7. Light module (7) according to claim 6, wherein the other surface resistance of the second part (45) of the conductive layer (40) is at least ten times smaller than the surface resistance of the first part (44) of the conductive layer (40).

8. Light module (5; 6; 7) according to any one of claims 1 to 7, wherein the radar antennas (100, 101) and the parasitic antennas (200, 201) are encapsulated in the intermediate layer (30).

9. Light module (5; 6; 7) according to any one of claims 1 to 8, wherein the protective panel (20) comprises a transparent polymer material.

10. Light module (5; 6; 7) according to any one of claims 1 to 9, wherein the protective panel (20) forms an external window of the motor vehicle (1).

Images