Vehicle assembly including radar sensor and light-emitting signaling module

Abstract

The present invention relates to a vehicle component (1), comprising: a radar sensor (10) configured to emit radar waves (R1) within a range (Δ1) of wavelengths (λ); and a light emitting module (13); the component being characterized in that the light emitting module (13) comprises a sublayer (14) and a pattern (150) layer (15), the pattern (150) layer (15) forming a repetition period of a pattern (150) that is less than one quarter of the wavelength (λ) within the range (Δ1), and characterized in that the total thickness (e0) of the light emitting module (13) is equal to m multiplied by the wavelength (λ) within the range (Δ1), as a whole divided by the product of twice the equivalent refractive index of the sublayer (14) and the pattern (150) layer (15) and the cosine of the refraction angle corresponding to the angle of incidence of the radar wave (R1), wherein m is an integer.

Description

Technical Field

[0001] The present invention relates to a vehicle assembly for a vehicle having particular, but not limiting, application in motor vehicles. Background Art

[0002] More and more radar sensors are used to detect objects in the external environment of a motor vehicle and estimate their angular position and accordingly perform automatic emergency braking, speed regulation or even blind spot detection functions. Conventionally, these radar sensors are mounted behind the bumper of the motor vehicle.

[0003] One disadvantage of this prior art is that integration behind the bumper reduces the performance capabilities of the radar sensor due to the metallized paint layer applied to the bumper and due to the curved shape of the bumper. This results in a poor estimation of the angular position of objects. Summary of the Invention

[0004] In this context, the object of the present invention is to propose a vehicle assembly allowing to resolve the above-mentioned drawbacks.

[0005] To this end, the present invention proposes a vehicle component for a vehicle, the vehicle component comprising:

[0006] - a radar sensor configured to transmit radar waves within a range of wavelengths; and

[0007] - a lighting module configured to perform a signaling function;

[0008] -characterized in thatthe light-emitting module comprises a sublayer and a pattern layer, wherein the pattern layer forms a subwavelength structured dielectric element, the subwavelength structured dielectric element having a pattern repetition period that is less than one-quarter of the wavelength in the range, and characterized in thatthe total thickness of the light-emitting module is equal to m multiplied by the wavelength in the range, the whole divided by the product of twice the equivalent refractive index of the sublayer and the pattern layer and the cosine of the refraction angle corresponding to the incident angle of the radar wave, wherein m is an integer.

[0009] According to a non-limiting embodiment, the vehicle assembly may additionally comprise one or more additional features selected from the following, alone or in any technically possible combination.

[0010] According to a non-limiting embodiment, the radar sensor is a millimeter wave, ultra-high frequency wave, or microwave radar sensor.

[0011] According to one non-limiting embodiment, the radar waves are emitted in a frequency band ranging between 100 MHz and 5 GHz.

[0012] According to one non-limiting embodiment, the repetition period of the pattern is less than one tenth of the wavelength of the radar waves.

[0013] According to one non-limiting embodiment, the pattern is a segment of a cylindrical prism, or a rectangular prism, or a pyramidal prism, or a cubic prism, or a torus.

[0014] According to one non-limiting embodiment, the pattern has a size smaller than 0.4 mm.

[0015] According to one non-limiting embodiment, the total thickness is formed by the height of the pattern and the thickness of the sub-layer.

[0016] According to one non-limiting embodiment, if the angle of incidence is equal to zero, the total thickness is equal to the wavelength divided by twice the equivalent refractive index.

[0017] According to one non-limiting embodiment, the total thickness is defined by an angle of incidence equal to arctan(d1 / (2e4)), where e4 is the distance between the radar sensor and the lighting module, and d1 is the distance between the transmitter antenna and the receiver antenna of the radar sensor.

[0018] According to a non-limiting embodiment, the light-emitting module further includes a reflective layer, and the total thickness of the light-emitting module is equal to m multiplied by the wavelength in the range, divided as a whole by the product of twice the equivalent refractive index of the sub-layer, the patterned layer, and the reflective layer and the cosine of the refraction angle corresponding to the incident angle of the radar wave, where m is an integer.

[0019] According to one non-limiting embodiment, the equivalent refractive index is calculated for an angle of incidence of the radar wave equal to the center of the field of view of the radar sensor.

[0020] According to a non-limiting embodiment, the lighting module is a daylight lighting module, or an indicator light, or a retro-reflector, or a high-mounted parking light.

[0021] A light-emitting module is also proposed, which is arranged facing a radar sensor, and the radar sensor is configured to emit radar waves within a range of wavelengths, wherein the light-emitting module is configured to perform a signaling function and includes a sublayer and a pattern layer, characterized in that the pattern layer forms a subwavelength structured dielectric element, and the subwavelength structured dielectric element has a pattern repetition period that is less than one-quarter of the wavelength in the range, and characterized in that the total thickness of the light-emitting module is equal to m multiplied by the wavelength, divided by the product of twice the equivalent refractive index of the sublayer and the pattern layer and the cosine of the refraction angle corresponding to the incident angle of the radar wave, where m is an integer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention and its various applications will be better understood by reading the following description and referring to the accompanying drawings, in which:

[0023] Figure 1 is a schematic diagram of a vehicle assembly according to a non-limiting embodiment of the present invention, the vehicle assembly including a radar sensor and a lighting module;

[0024] Figure 2 According to a non-limiting embodiment, Figure 1 Schematic diagram of radar waves emitted by a radar sensor, wherein the radar waves Figure 1 The light emitting module is partially reflected;

[0025] Figure 3 According to a non-limiting embodiment Figure 1 A schematic diagram of a light-emitting module, wherein the light-emitting module includes a sub-layer and a pattern layer;

[0026] Figure 4 According to a non-limiting embodiment Figure 3 A perspective view of a local area of ​​a pattern of a pattern layer of a light emitting module;

[0027] Figure 5 According to a non-limiting embodiment, Figure 1 Schematic diagram of radar waves emitted by a radar sensor, wherein the radar waves Figure 1 The light emitting module comprises an additional layer as a reflective layer.

[0028] Unless otherwise stated, structurally or functionally identical elements appearing in the various figures are given the same reference numerals. DETAILED DESCRIPTION

[0029] refer to Figures 1 to 5 A vehicle assembly 1 of a vehicle 2 according to the present invention is described. Vehicle assembly 1 is also referred to as vehicle system 1. In one non-limiting embodiment, vehicle 2 is a motor vehicle. Motor vehicle is understood to mean any type of motor vehicle. Throughout the remainder of the description, this embodiment is to be regarded as a non-limiting example. Throughout the remainder of the description, vehicle 2 is also referred to as motor vehicle 2. In another non-limiting embodiment, vehicle assembly 1 is arranged in a lighting device or signaling device (located at the front or rear) of motor vehicle 2.

[0030] like Figure 1 As shown in FIG, a lamp device for a vehicle 2 includes:

[0031] a radar sensor 10 having a field of view FOV and configured to emit radar waves R1 within a range Δ1 of wavelength λ in said field of view FOV;

[0032] A lighting module 13 configured to perform a signaling function f1 (also referred to as function f1 ). It is therefore also referred to as a signaling lighting module 13 .

[0033] The vehicle assembly 1 further comprises an output outer lens 12. The output outer lens 12 may or may not form part of the light module 13.

[0034] The radar sensor 10 is described below. Figure 1 As shown in FIG, the radar sensor 10 is arranged to face the light emitting module 13. In a non-limiting embodiment, the radar sensor 10 is a millimeter wave (between 24 GHz and 300 GHz) or ultra-high frequency wave (between 300 MHz and 81 GHz) or microwave (between 1 GHz and 300 GHz) radar sensor. In a non-limiting alternative embodiment, the radar sensor 10 operates at a radar frequency ranging from 76 GHz to 81 GHz. In a non-limiting embodiment, the radar wave R1 is emitted in a frequency band ranging from 100 MHz to 5 GHz. Therefore, in a non-limiting example, if the sensor operates at a radar frequency of 77 GHz (i.e., a wavelength λ of 3.95 mm) with a frequency band of 1 GHz, the radar sensor 10 will operate in a frequency band of 76.5 GHz to 775 GHz. Therefore, the radar wave R1 will be emitted in a frequency range of 76.5 GHz to 77.5 GHz (i.e., a range Δ1 of a wavelength λ of 3.87 mm to 392 mm). Therefore, in another non-limiting example, if radar sensor 10 operates at a radar frequency of 78.5 GHz in a 5 GHz band, radar sensor 10 will operate in a frequency band of 76 GHz to 81 GHz. Therefore, radar waves R1 will be emitted within a frequency range of 76 GHz to 81 GHz (i.e., a range Δ1 of wavelengths λ of 3.701 mm to 3.945 mm).

[0035] like Figure 2 , the emitted radar wave R1 arrives at the light emitting module 13 at an angle of incidence θ. In one non-limiting embodiment, the angle of incidence θ is in the range between 0° and + / - 30°. Therefore, the field of view FOV varies between -30° and +30°. The center of the field of view FOV is at an angle of 0° relative to the longitudinal axis of the vehicle (also referred to as the axis of the vehicle). In another non-limiting embodiment, the field of view FOV therefore varies between -90° and +45°. The center of the field of view FOV is at an angle of -45° relative to the axis of the vehicle, and the angle of incidence θ of the radar wave R1 on the light emitting module 13 remains close to 0° (wherein the vehicle component 1 is then positioned at approximately 45° to the axis of the vehicle).

[0036] The radar sensor 10 is configured to scan the external environment of the motor vehicle 2 by means of the emission of radar waves R1. Figure 1 As illustrated in FIG, the radar sensor 10 thus comprises:

[0037] at least one transmitter antenna 100 configured to transmit a radar wave R1 (also referred to as a primary radar wave R1 );

[0038] At least two receiver antennas 101 configured to receive radar waves R2 (also referred to as secondary radar waves R2 or return radar waves R2 ).

[0039] Radar sensor 10 also includes at least one transmitter 103 configured to generate primary radar waves R1 and at least one receiver 104 configured to process received, returned secondary radar waves R2. In one non-limiting embodiment, a single electronic component can be used for both (transmitting and receiving) functions. Therefore, one or more transceivers will be present. Transmitter 103 generates primary radar waves R1, which are then transmitted by transmitter antenna 100. When this wave encounters an object 3 in the external environment of motor vehicle 2 (in this case, a pedestrian in the illustrated non-limiting example), it is reflected from the object 3. These reflected radar waves are then transmitted back to radar sensor 10. These are secondary radar waves R2 received by receiver antenna 101. These are the radar waves retransmitted toward radar sensor 10. In one non-limiting embodiment, primary radar waves R1 and secondary radar waves R2 are radio frequency waves. In one non-limiting embodiment, radar sensor 10 includes multiple transmitters 103 and multiple receivers 104.

[0040] Transmitter antenna 100 (also referred to as antenna 100) is configured to transmit primary radar waves R1 generated by transmitter 103. Receiver antenna 101 (also referred to as antenna 101) is configured to receive secondary radar waves R2 and transmit them to receiver 104, which then processes them. A phase shift exists between secondary radar waves R2 received by receiver antenna 101, which allows the angular position of object 3 located in the external environment of motor vehicle 2 to be deduced relative to motor vehicle 2. In a non-limiting embodiment, antennas 100, 101 are patch antennas or slot antennas.

[0041] In one non-limiting embodiment, antennas 100, 101, transmitter 103, and receiver 104 are disposed on a printed circuit board 105. In one non-limiting embodiment, the printed circuit board is a rigid printed circuit board (also referred to as a printed circuit board assembly (PCBA)) or a flexible printed circuit board (also referred to as a "flexboard").

[0042] The radar sensor 10 further comprises an electronic control unit 106 configured to control the transmitter 103 and the receiver 104. Since radar sensors are known to those skilled in the art, they will not be described in further detail herein.

[0043] The lighting module 13 is described below. The lighting module 13 is configured to perform the signaling function f1. In a non-limiting embodiment, the lighting module 13 is a daylight lighting module, an indicator light, a retro-reflector, or a high-mounted parking light.

[0044] The light emitting module 13 has a refractive index n corresponding to the wavelength λ in the wavelength range Δ1. eq It should be noted that due to the optical design of the signalling function f1 (and therefore of the layer 15 (also referred to as optical layer 15 ) described below), n1 may be variable, which means that the equivalent refractive index n eq is variable. This must be taken into account in the calculation of the thickness e0 described below.

[0045] like Figure 2 and Figure 3 As shown in FIG, the light emitting module 13 includes a sublayer 14 and a pattern 150 layer 15. The sublayer 14 is configured to support the pattern 150 layer 15. The sublayer 14 is arranged to directly face the radar sensor 10. The refractive index of the sublayer 14 is n2. In a non-limiting embodiment, the sublayer 14 is made of plastic, glass or ceramic material. In a non-limiting example, the plastic is polycarbonate. The pattern 150 layer 15 forms a subwavelength structured dielectric element. It has a refractive index n1 (also called a local refractive index n1), which depends on the pattern 150 and its spacing. The pattern 150 is defined during the optical design to perform the signaling function f1. In a non-limiting embodiment, the pattern 150 is used to decouple light in the visible light guide or to shape the light beam emitted by the light emitting module 13. The pattern 150 is defined so that when the function f1 is turned on, it meets the aesthetic requirements of the light beam of the light emitting module 13 and its visible appearance. Therefore, the optical design is applied regardless of the presence or absence of radar sensor 10 , in particular in order not to create several versions of optical layer 15 .

[0046] In non-limiting embodiments, the dielectric element is made of plastic, glass, or ceramic. In one non-limiting example, the plastic is polycarbonate. As a reminder, unlike conductive materials, dielectric materials are non-conductive, thus allowing radar waves R1 to pass through. When radar waves R1 are emitted by radar sensor 10 , they first encounter sub-layer 14 , then pattern 150 layer 15 , and finally, output outer lens 12 .

[0047] "Structured" is understood to mean that layer 15 includes a pattern 150 (also referred to as a structure). "Subwavelength" is understood to mean that the structured dielectric material has a scale smaller than the wavelength λ of the range Δ1. The fact that pattern 150 of layer 15 is subwavelength allows this layer 15 to be modeled as a variable refractive index layer. Otherwise, layer 15 would have to be considered a diffractive optical element.

[0048] like Figure 4 As shown in the figure, Figure 4 is a view of a local area Z1 of a pattern 150 of layer 15, the pattern 150 having dimensions a1 (width), a2 (width), h1 (height). In a non-limiting embodiment, the pattern 150 is a cylindrical prism (also called a cylindrical column), or a rectangular prism (also called a rectangular column), or a pyramidal prism (also called a pyramidal column), or a cubic prism (also called a square column) (the latter case is in Figure 4 ) or even segments of a torus. They can also take on any other parallelepiped shape. In one non-limiting embodiment, pattern 150 has dimensions a1, a2 that are less than 0.4 mm. This value is very small compared to the wavelength λ of the range Δ1. For example, at a frequency of 77 GHz, the wavelength λ is 4 mm; in this case, the values ​​of a1, a2 are approximately equal to λ / 10.

[0049] like Figure 3 and 4 As shown in FIG, the pattern 150 layer 15 is composed of individual units 152, each of which includes a pattern 150 and an inflatable segment, i.e., an air-filled segment, surrounding the pattern 150. Figure 3 In one non-limiting alternative embodiment illustrated in FIG, the pattern 150 is adjacent on a boundary surface between the layer 15 and the sub-layer 14 (where they abut on that boundary surface). This non-limiting alternative embodiment is applicable to patterns 150 in the shape of segments of a pyramid or a torus. The individual cells 152 are defined by a repetition period Λ of the structure 150 (also referred to as the repetition period Λ of the pattern 150 or even the grating period Λ), where Λ=Λ1xΛ2. Λ1 is the grating period in the first direction Ax (e.g., Figure 4 ), and Λ2 is the grating period in the second direction Ay (as shown in Figure 4 ( , as shown in FIG. ). Ax and Ay are arbitrary directions that are not parallel to each other. In one non-limiting embodiment, the second direction Ay is perpendicular to the first direction Ax. In another non-limiting example, the individual cells 152 are squares, hexagons, parallelograms, or any other shape that allows the boundary surface between the layer 15 and the sublayer 14 to be periodically tiled. A third direction perpendicular to the first and second directions Ax and Ay will be denoted as Az, and these directions together form the Ax, Ay, and Az reference system.

[0050] In a first non-limiting embodiment, the subwavelength structured dielectric element forming layer 15 has a constant refractive index n1. It is a periodic subwavelength structured dielectric element. The dimensions a1, a2 of pattern 150 remain constant, and Λ1 and Λ2 are also constant. In other words, the patterns 150 are equally spaced from each other in the first direction Ax and equally spaced in the second direction Ay. In other words, the layer 15 between the patterns 150 has the same spacing 151x in the first direction Ax and the same spacing 151y in the second direction Ay (e.g., Figure 4 ), that is, there is the same amount of air between the patterns 150.

[0051] In a second non-limiting embodiment, the subwavelength structured dielectric element forming layer 15 has a variable refractive index n1. In the first non-limiting alternative embodiment, it is a periodic unit subwavelength structured dielectric element. The dimensions a1 and a2 of pattern 150 vary along layer 15, thereby changing the refractive index n1 of layer 15, while Λ1 and Λ2 are constant. In a second non-limiting alternative embodiment, it is a non-periodic unit subwavelength structured dielectric element. Λ1 and Λ2 vary along layer 15, thereby changing the refractive index n1 of layer 15, while the dimensions a1 and a2 of pattern 150 can remain constant. Layer 15 includes variable spacing 151x and 151y between patterns 150, that is, there are different amounts of air between patterns 150. Therefore, in this second alternative embodiment, Λ1 and Λ2 and dimensions a1 and a2 of pattern 150 can be varied to change the refractive index of layer 15. In one non-limiting example, for patterns 150 in the form of segments of a torus, the radius of curvature is variable between patterns 150. In another non-limiting example, for patterns 150 in the form of truncated pyramids, it is the truncation height that varies.

[0052] "Subwavelength" is understood to mean that the grating periods Λ1, Λ2 are less than one-quarter of the wavelength λ of the wavelength λ range Δ1. In one non-limiting example, the wavelength λ considered is the shortest wavelength in the range Δ1. Thus, Λ1 < λ / 4 and Λ2 < λ / 4. In one non-limiting embodiment, the grating periods Λ1, Λ2 are less than one-tenth of the wavelength λ. Thus, Λ1 < λ / 10 and Λ2 < λ / 10. It should be noted that this wavelength λ is selected from the range Δ1 and will be the wavelength λ used in the following formulas.

[0053] like Figure 2As shown in the figure, when the radar wave R1 is emitted by the radar sensor 10, the radar wave R1 propagates to the light emitting module 13 having a thickness e0. The radar wave R1 reaches the light emitting module 13 at an incident angle θ corresponding to the refraction angle r. The radar wave R1 is reflected on the light emitting module 13 and generates two reflected waves, one of which, R11, has been reflected on the outside of the sublayer 14 of the light emitting module 13, and the other has been reflected inside the light emitting module 13. The two reflected waves R11 and R12 are reflected waves (called first-order reflected waves) that return to the radar sensor 10. These are stray light reflections. When the incident angle O is different from 0°, the corresponding refraction angle r is also different from 0°. The phase difference between the two reflected waves R11 and R12 is (Also called phase shift )equal:

[0054] [Mathematical function 1]

[0055]

[0056] in:

[0057] -n eq is the equivalent refractive index of sublayer 14 and layer 15;

[0058] -δ is the path of the reflected wave R12 in the material, which is equal to 2e0 / cos(r);

[0059] -nδ / λ is the phase shift due to the path through the material;

[0060] -π is the phase shift due to internal reflections in the sub-layer 14 and the pattern 150 layer 15;

[0061] --((2e0tan(r)sin(θ)) / λ) is a phase shift in the air caused by the difference between the reflection point Pt1 of the reflected wave R11 and the appearance point Pt2 of the reflected wave R12.

[0062] Since sin(θ)=n eq x sin(r), so we get the following:

[0063] [Mathematical function 2]

[0064]

[0065] Right now:

[0066] [Mathematical function 3]

[0067]

[0068] And this is the case regardless of the value of the refraction angle r.

[0069] Since the reflected waves R11 and R12 return to the radar sensor 10, they cause interference on the radar sensor 10, that is, they cause a decrease in the signal-to-noise ratio. In order to eliminate this interference, the total thickness e0 of the light emitting module 13 will be defined so that the reflected waves R11 and R12 have opposite phases to produce destructive interference. In order to obtain destructive interference, the phase difference between the two reflected waves R11 and R12 is Modulo 2π must equal π. Therefore, Where m is a natural integer. Therefore, the following results are obtained:

[0070] [Mathematical function 4]

[0071]

[0072] Right now:

[0073] Let e0=mλ / (2n eq cos(r)).

[0074] It should be noted that regardless of the value of the angle r, the equation e0 = mλ / (2n eq cos(r)) applies. Therefore, the total thickness e0 is dimensioned so that it is equal to m multiplied by the wavelength λ, the whole divided by the equivalent refractive index n of the pattern 150 layer 15 and the sublayer 14 eq The product of twice the cosine of the refraction angle r corresponding to the incident angle θ of the radar wave R1, where m is an integer. Therefore, based on the equivalent refractive index n eq The total thickness e0 can be determined by using a wavelength λ within the operating frequency range of the radar sensor 10 so that the reflected waves R11 and R12 cancel each other. In a non-limiting embodiment, the wavelength λ used is a wavelength located in the middle of the allowed range Δ1.

[0075] When the incident angle θ is equal to 0 and m is equal to 1, the ideal total thickness e0 is defined. When θ=0, r=0. Therefore, for m=1, the ideal total thickness e0 of the light emitting module 13 is thus e0=λ / (2n eq ). When r = 0°, cos(r) = 1.

[0076] In one non-limiting embodiment, the light emitting module 13 has a total thickness e0 in the range of 0.8 to 1.2 times the ideal total thickness e0. This range of values ​​takes into account the possible emission angles of the radar sensor 10. It should be noted that the value of the angle of incidence θ is included in the possible emission angles of the radar sensor 10. The possible values ​​of the angle of incidence θ are defined in the technical specifications of the radar sensor 10, which means that the possible values ​​of the angle of incidence θ are within the field of view of the radar sensor 10. In one non-limiting example, the angle of incidence θ is in the range of 0° to + / - 30°. The range of values ​​from 0.8 to 1.2 allows for manufacturing tolerances of the total thickness e0 to be taken into account.

[0077] It should be noted that there is a value of the incident angle of 0, for which the reflected radar waves R11 and R12 cause the maximum interference to the receiver antenna 101 of the radar sensor 10. This incident angle θ is called the critical incident angle θ. In one non-limiting embodiment, this value is equal to θ = arctan (d1 / (2e4)), where d1 is the distance between the transmitter antenna 100 and the receiver antenna 101, and e4 is the distance between the radar sensor 10 and the light module 11. Figure 2 It should be noted that, in one non-limiting example, the midpoint of the receiver antenna 101 is taken to calculate d1.

[0078] Therefore, based on the value of the local refractive index n1 and the value of the wavelength λ used within the operating frequency range of the radar sensor 10 (in the non-limiting example used, between 76 GHz and 81 GHz), the value of the total thickness e0 can be determined so that the first-order reflected waves R11 and R12 cancel each other. The reflected radar waves R11 and R12 are reflected within a limited area on the light emitting module 13.

[0079] It should be noted that when the light emitting module 13 has a variable equivalent refractive index n eq In a non-limiting embodiment, the thickness e0 of the light emitting module 13 is found to have a variable equivalent refractive index n. eq In this case, the thickness e0 is variable along the surface of the light emitting module 13. In contrast, when the light emitting module 13 has a constant equivalent refractive index n eq In this case, the thickness e0 is adjusted for the entire surface of the light emitting module 13. Therefore, the thickness e0 is constant along the surface of the light emitting module 13.

[0080] The light emitting module 13 has a total thickness e0 formed by the height h1 of the pattern 150 and the thickness e2 of the sublayer 14. To determine the size of the total thickness e0, the thickness e2 of the sublayer 14 is adjusted so that for a given r, e0=mλ / (2n eqcoS(r). In this way, the pattern 150 imposed by the optical design is not modified. In one non-limiting embodiment, the given r corresponds to the critical angle of incidence θ.

[0081] Therefore, the receiver antenna 101 sees less noise and a better signal-to-noise ratio is achieved.

[0082] Equivalent refractive index n eq equal:

[0083] [Mathematical function 5]

[0084]

[0085] Where n1 is the local refractive index of the pattern 150 layer 15, n2 is the refractive index of the sub-layer 14, e1 is the height h1 of the pattern 150, and e2 is the thickness of the sub-layer 14. When the light-emitting module 13 is a gradient refractive index light-emitting module, it should be noted that n1 depends on the position of the local area Z1 of the pattern 150 on the layer 15 for which it is calculated. Therefore, the equivalent refractive index n eq It depends on the position of the local area Z1 on the layer 15. When the light-emitting module 13 is not a gradient refractive index light-emitting module, the calculation can be performed at any point of the pattern 150 layer 15 (ie, in any area Z1).

[0086] It should be noted that the layer 15 of patterns 150 has a local refractive index n1 which depends on the local density τ of said patterns 150 in the layer 15. r The local density τ at the point of the light emitting module 13 is calculated. r is the filling factor τ of each cell 152 located at a distance from the point under consideration r152 The weighted average of the distances is less than a given value of the order of magnitude of one wavelength in the wavelength range Δ1 used. The local refractive index n1 is also called the effective refractive index n eff , and consists of two effective refractive indices n effTE and n effTM These two effective refractive indices depend on the polarization of the incident wave (i.e., the main radar wave R1) and can be expressed as the local density τ r (also known as the filling factor τ r ), which represents the amount of material occupied by a medium with a high refractive index n1 (in this case, pattern 150) relative to a medium with a low refractive index n0 (in this case, air). It should be noted that the local density τ r expresses the amount of material occupied by the medium with high refractive index n1 in an area of ​​the order of magnitude of one wavelength in the wavelength λ of the wavelength range Δ1 used. This gives:

[0087] [Mathematical Function 6]

[0088]

[0089] [Mathematical Function 7]

[0090]

[0091] The term TE represents the polarization of the incident wave (ie, the radar wave R1 reaching the light module 13 in this case) perpendicular to the plane of the substrate (ie, the sublayer 14), TM represents the polarization parallel to the plane of the substrate, and ε max represents the dielectric constant of the medium with the highest refractive index (ie, pattern 150), and ε min represents the dielectric constant of the medium with the lowest refractive index (ie air in this case). In another non-limiting embodiment, the air can be replaced by a plastic with a very low refractive index.

[0092] It should be noted that when an incident wave (in this case a radar wave R1) strikes the structured dielectric element (i.e., layer 15) and has a wavelength λ (within the range Δ1) that is much larger than the repetition period Λ1, Λ2 of the structure 150 (λ>>Λ1 and λ>>Λ2), this involves a propagation state known as the static limit.

[0093] For a two-dimensional structure 150 such as Figure 4 The effective refractive index n of the two-dimensional structure is eff2D It can be approximated by taking the mean square of the effective refractive indices of the two polarizations TM and TE in one dimension of order 0 corresponding to the static limit. In this particular case, the filling factor τ of the individual cells 152 is r152 yes:

[0094] [Mathematical Function 7]

[0095]

[0096] as well as:

[0097] [Mathematical function 8]

[0098]

[0099] In the more general case, for any shape of pattern 150 with any Λ1, Λ2 and with individual cells 152 having rectangular bases, the filling factor τ of the individual cells 152 is r152 will be:

[0100] [Mathematical function 9]

[0101]

[0102] It corresponds to the volume of material in the individual cells 152 (V 152 ) to the empty package volume (Λ1.Λ2.hmax), where hmax is the maximum height of the pattern 150 in the individual cells 152 (ie, the highest height in the pattern 150); and

[0103] [Mathematical Function 10]

[0104]

[0105] Where (X 152 , Y 152 , 0) are the coordinates of the corner C1 of the single cell 152, and if the point of coordinates (X, Y, Z) is located in the material, then M(X, Y, Z) = 1, if not, that is, if the point of coordinates (X, Y, Z) is located in the air, then M(X, Y, Z) = 0. It should be noted that when it is located in the material, the point is located in the pattern 150 of the individual cell 152, and when it is located in the air, the point may or may not be located within the pattern 150 (because in one non-limiting example, the pattern 150 may actually contain pores). It should be noted that in Figure 4 In the non-limiting example described above, hmax=h1.

[0106] It should be noted that regardless of the shape of the pattern 150 in the individual cells 152, the material V 152 This formula for the volume of is valid for any individual cell 152 with a rectangular base. Thus, since Λ1 and A2 may vary from one individual cell 152 to another, and since the maximum height hmax may vary from one pattern 150 to another, each individual cell 152 may contain a different amount of material and therefore have a different fill factor τ. r152 In order to obtain a filling factor τ of the entire layer 15 of pattern 150 at a given point of the light emitting module 13 r , calculate the filling factor τ of each cell 152 located at a distance from the considered point on the light module 13 r152 The weighted average of the distances is less than a given value of the order of magnitude of one wavelength λ of the wavelength range Δ1 used. This definition is valid for all points of the light module 13. In a non-limiting embodiment, these points belong to the surface of the sublayer 14 with coordinate Z=0.

[0107] This gives:

[0108] [Mathematical Function 11]

[0109]

[0110] Here n denotes any individual cell of the individual cells 152 located at a distance from the considered point on the lighting module 13 that is smaller than a given value of the order of magnitude of one of the wavelengths λ of the wavelength range Δ1 used.

[0111] exist Figure 5 In a non-limiting embodiment shown in FIG, the light emitting module 13 further includes a reflective layer 16 for the radar sensor 10 in the field of visible light and transparent light or weakly absorbed light, wherein the reflective layer has a refractive index n3 for radar waves. In this case, the total thickness e0 of the light emitting module 13 is equal to m multiplied by the wavelength λ of the range, divided by the equivalent refractive index n of the sub-layer 14, the pattern layer 150, and the reflective layer 16. eq The product of twice and the cosine of the refraction angle r corresponding to the incident angle θ of the radar wave R1, where m is an integer. Therefore, for an incident angle θ equal to zero, the total thickness e0 of the light emitting module 13 is equal to the wavelength λ divided by the equivalent refractive index n of the sub-layer 14, the pattern layer 150, and the reflective layer 16. eq Therefore, when calculating the equivalent refractive index n eq , this reflective layer 16 is taken into account. Therefore, the previous calculations must also take into account the refractive index n3. The reflective layer 16 covers the pattern 150 layer 15. In a non-limiting example, the reflective layer 16 is an indium layer or a reflective lacquer layer covering the pattern 150.

[0112] Of course, the description of the present invention is not limited to the above-described embodiments and fields. Therefore, in another non-limiting embodiment, the radar sensor 10 includes more than one transmitter antenna 100 and more than two receiver antennas 101. Therefore, in a non-limiting embodiment, the light emitting module 13 may include more than three layers. Therefore, the equivalent refractive index n eq The calculation will take into account all layers that form the lighting module 13. Therefore, in one non-limiting embodiment, the vehicle component 1 also includes an additional lighting module configured to perform a lighting function, the additional lighting module including a housing. Therefore, the additional lighting module is a lighting module. In a non-limiting example, the additional lighting module is a headlight, a taillight, or a fog light. In this embodiment, the signaling light module 13 and the radar sensor 10 are integrated into the housing of the lighting module, and the signaling light module 13 is arranged next to the lighting module. It should be noted that integrating the radar sensor 10 behind the signaling light module 13 rather than behind the lighting module allows circumventing manufacturer requirements that tend to limit the space behind the lighting module. It should be noted that the lighting module is typically much larger in the longitudinal direction than the signaling light module. Therefore, there is often insufficient space to place the radar sensor 10 behind the lighting module.

[0113] The invention described thus has, inter alia, the following advantages:

[0114] - Integrating the radar sensor 10 behind the signaling light module 13 instead of behind the bumper avoids reducing the performance capability of the radar sensor 10;

[0115] It allows to eliminate the first-order reflected waves R11, R12 reflected towards the radar sensor 10. Therefore, the signal-to-noise ratio of said radar sensor 10 is no longer low.

Claims

1. A vehicle component (1) for a vehicle (2), the vehicle component (1) comprising: - a radar sensor (10) configured to emit radar waves R1 within a range Δ1 of wavelength λ; and - a lighting module (13) configured to perform a signaling function f1; -characterized in that the light emitting module (13) comprises a sublayer (14) and a pattern (150) layer (15), the pattern (150) layer (15) forming a subwavelength structured dielectric element, the subwavelength structured dielectric element having a repetition period Λ1, Λ2 of the pattern (150) that is less than one quarter of the wavelength λ of the range Δ1, and the total thickness e0 of the light emitting module (13) is equal to m multiplied by the wavelength λ of the range, as a whole divided by the equivalent refractive index n of the sublayer (14) and the pattern (150) layer (15). eq The product of twice and the cosine of the refraction angle r corresponding to the incident angle θ of the radar wave R1, where m is an integer.

2. The vehicle component (1) according to claim 1, wherein The radar sensor (10) is a millimeter wave, ultra-high frequency wave, or microwave radar sensor.

3. The vehicle component (1) according to claim 2, wherein The radar wave R1 is emitted in a frequency band ranging between 100 MHz and 5 GHz.

4. The vehicle component (1) according to any one of claims 1 to 3, wherein The repetition periods Λ1, Λ2 of the pattern (150) are smaller than one tenth of the wavelength λ of the radar wave R1.

5. The vehicle component (1) according to any one of claims 1 to 3, wherein The pattern (150) is a segment of a cylindrical prism, or a rectangular prism, or a pyramidal prism, or a cubic prism, or a torus.

6. The vehicle component (1) according to any one of claims 1 to 3, wherein The pattern (150) has dimensions a1, a2 less than 0.4 mm.

7. The vehicle component (1) according to any one of claims 1 to 3, wherein The total thickness e0 is formed by the height h1 of the pattern (150) and the thickness e2 of the sub-layer (14).

8. The vehicle component (1) according to claim 7, wherein If the incident angle θ is equal to zero, the total thickness e0 is equal to the wavelength λ divided by the equivalent refractive index n eq twice as much.

9. The vehicle component (1) according to any one of claims 1 to 3, wherein The total thickness e0 is defined by an angle of incidence θ equal to arctan(d1 / (2e4)), where e4 is the distance between the radar sensor (10) and the light emitting module (13), and d1 is the distance between the transmitter antenna (100) and the receiver antenna (101) of the radar sensor (10).

10. The vehicle component (1) according to any one of claims 1 to 3, wherein The light emitting module (13) further includes a reflective layer (16), and the total thickness e0 of the light emitting module (13) is equal to m multiplied by the wavelength λ in the range, divided as a whole by the equivalent refractive index n of the sublayer (14), the pattern (150) layer (15), and the reflective layer (16). eq The product of twice and the cosine of the refraction angle r corresponding to the incident angle θ of the radar wave R1, where m is an integer.

11. The vehicle component (1) according to any one of claims 1 to 3, wherein The equivalent refractive index n is calculated for an incident angle θ of the radar wave R1 equal to the center of the field of view FOV of the radar sensor (10). eq .

12. The vehicle component (1) according to any one of claims 1 to 3, wherein The light emitting module (13) is a daylight light emitting module, or an indicator light, or a retroreflector, or a high-mounted parking light.

13. A light emitting module (13) disposed facing a radar sensor (10), the radar sensor being configured to emit radar waves R1 within a range Δ1 of a wavelength λ, the light emitting module (13) being configured to perform a signaling function f1, and comprising a sublayer (14) and a pattern (150) layer (15), characterized in that: The pattern (150) layer (15) forms a sub-wavelength structured dielectric element having a repetition period Λ of the pattern (150) that is less than one quarter of the wavelength λ of the range Δ1, and the total thickness e0 of the light emitting module (13) is equal to m multiplied by the wavelength λ, as a whole divided by the equivalent refractive index n of the sub-layer (14) and the pattern (150) layer (15). eq The product of twice and the cosine of the refraction angle r corresponding to the incident angle θ of the radar wave R1, where m is an integer.

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