EP4162296A1

EP4162296A1 - Radar detection system for a vehicle

Info

Publication number: EP4162296A1
Application number: EP21728931.3A
Authority: EP
Inventors: Christophe GRARD
Original assignee: Valeo Vision SAS
Current assignee: Valeo Vision SAS
Priority date: 2020-06-09
Filing date: 2021-05-31
Publication date: 2023-04-12
Also published as: WO2021249806A1; CN115698762A; US20230314601A1; FR3111195A1

Abstract

The invention relates to a radar detection system (1) for a vehicle (2), said radar detection system (1) comprising: - a radar sensor (10) configured to emit/receive a plurality of radar waves (S1, S2), - a lighting element (11) arranged facing said radar sensor (10) and comprising at least one light source (110) configured to emit light rays (R1), and a plurality of layers (111) including a transparent layer (111a) configured to propagate said light rays (R1), characterized in that said layers (111) have substantially equal dielectric permittivities (ε).

Description

Title of the invention: Radar detection system of a vehicle

[1] The present invention relates to a radar detection system for a vehicle. It finds a particular but nonlimiting application in motor vehicles.

[2] In the field of motor vehicles, a radar detection system 5 of a vehicle well known to those skilled in the art illustrated in FIG. 1 comprises:

a radar sensor 50 configured to transmit / receive a plurality of radar waves S5,

a luminous element 51 arranged opposite said radar sensor and comprising at least one light source 510 configured to emit light rays, and a plurality of layers 511 including a transparent layer 511a configured to diffuse said light rays. The transparent layer 511a is delimited by two layers 511b and 511c.

[3] A drawback of this state of the art is that when the light element 51 is crossed by the radar waves from the radar sensor 50, the different layers 511 of the light element disturb the radar waves S5 emitted. Indeed, the different layers 511 represent different media that the radar waves must pass through. Each transition from one medium to another results in double reflections, namely the radar waves are reflected and then the reflections which are directed in the opposite direction to the radar waves are again reflected. There are thus several series of reflections S5 ′ illustrated in FIG. 1 of the radar waves S5 on these different layers 511, and on the surface of the radar sensor 50 itself. The reflected S5 ’radar waves mix with the transmitted S5 radar waves, which disrupts the emission of said radar waves.

[4] In this context, the present invention aims to provide a radar detection system of a vehicle which overcomes the mentioned drawback.

[5] To this end, the invention provides a radar detection system for a vehicle, said radar detection system, comprising:

- a radar sensor configured to transmit / receive a plurality of radar waves,

a light element arranged opposite said radar sensor and comprising at least one light source configured to emit light rays, and a plurality of layers including a transparent layer configured to propagate said light rays, characterized in that said layers have permittivities substantially equal dielectrics. [6] According to non-limiting embodiments, said radar detection system may further include one or more additional characteristics taken alone or in any technically possible combination, among the following.

[7] According to a nonlimiting embodiment, said transparent layer is a light guide.

[8] According to a non-limiting embodiment, said transparent layer is delimited by two layers including a dark layer.

[9] According to a non-limiting embodiment, said dark layer is placed opposite said radar sensor.

[10] According to a non-limiting embodiment, the other layer which delimits said transparent layer is a reflecting layer.

[11] According to a non-limiting embodiment, one of the layers other than the transparent layer is configured to produce a pattern.

[12] According to a nonlimiting embodiment, the dielectric permittivities of said layers are between 2.4 and 3.5.

[13] According to a nonlimiting embodiment, said radar sensor is a millimeter wave or microwave or microwave radar sensor

[14] According to a nonlimiting embodiment, said radar sensor operates at a radar frequency between 76GHz and 81GHz.

[15] According to a nonlimiting embodiment, said layer which produces a pattern is a reflective layer.

[16] According to a non-limiting embodiment, said transparent layer is an optical element configured to propagate the light rays from said at least one light source and direct them towards another layer.

[17] According to a non-limiting embodiment, said other layer is a reflective layer.

[18] According to a nonlimiting embodiment, said transparent layer is made of transparent polycarbonate, said dark layer is made of black polycarbonate, and said reflecting layer is made of indium coated polycarbonate.

[19] The invention and its various applications will be better understood on reading the following description and examining the accompanying figures: [20] [Fig. 1] is a schematic view of a radar detection system of a vehicle according to the prior art, the radar detection system comprising a radar sensor and a light element with at least one light source and a plurality of layers,

[21] [Fig. 2] is a schematic view of a radar detection system of a vehicle, the radar detection system comprising a radar sensor and a light element with at least one light source and a plurality of layers, according to an embodiment not limiting the invention,

[22] [Fig. 3] is a schematic view of the radar sensor of the radar detection system of FIG. 2, according to a non-limiting embodiment,

[23] [Fig. 4] is a schematic front view of a pattern produced in one of the layers of the light element of the radar detection system of FIG. 2, according to a non-limiting embodiment,

[24] [Fig. 5] is a schematic view of radar wave reflections from the radar sensor on said plurality of layers of the light element of the radar detection system of Figure 2, said plurality of layers being seen as a single layer by the radar waves which pass through it and on which said radar waves are reflected, according to a non-limiting embodiment.

[25] Elements which are identical, by structure or by function, appearing in different figures retain the same references, unless otherwise specified.

[26] The radar detection system 1 according to the invention is described with reference to Figures 2 to 5. In a non-limiting embodiment, the vehicle 2 is a motor vehicle. By motor vehicle is meant any type of motor vehicle. This embodiment is taken as a non-limiting example in the remainder of the description. In the remainder of the description, the vehicle 2 is thus otherwise called motor vehicle 2.

[27] As illustrated in Figure 2, in a non-limiting embodiment, the radar detection system 1 is integrated behind the grille at the front of the motor vehicle 2. In another non-limiting embodiment, the Radar detection system is integrated in the grille at the rear of the motor vehicle 2.

[28] As illustrated in Figure 2, the radar detection system 1 comprises:

- a radar sensor 10,

- a light element 11.

[29] In a non-limiting embodiment, the radar sensor 10 is a radar for detecting objects 3 (pedestrian, bicycle, vehicle, tree, etc.) which are located in the external environment of the vehicle. motor vehicle 2. A non-limiting example of an object 3 is illustrated in FIG. 3. It is a pedestrian in the non-limiting example. In a non-limiting embodiment, the radar sensor 10 is a millimeter wave (between 24 GHz and 300 GHz) or microwave (between 300 MHz and 79 GHz) or microwave (between 1 GHz and 300 GHz) radar sensor. In a non-limiting variant embodiment, the radar sensor 10 operates at a radar frequency of between 76 and 81 GHz. The radar sensor 10 is configured to transmit / receive radar waves S1, S2.

[30] As illustrated in Figure 3, the radar sensor 10 comprises:

a transmitter 100 configured to generate a plurality of SI radar waves, otherwise called SI primary radar waves,

a receiver 101 configured to process a plurality of radar waves S2, otherwise called secondary radar waves S2,

- several antennas 102.

[31] In a nonlimiting embodiment, a single electronic component can be used for both transmission and reception functions. There will thus be one or more transmitter / receiver. Said transmitter 100 is configured to generate primary radar waves SI, which when they encounter an object 3 in the external environment of the vehicle 2 are reflected (bounced back) on said object 3. The radar waves thus reflected are waves transmitted back to the radar sensor 10. These are the secondary radar waves S2 received by the antennas 102 and processed by the receiver 101. In a non-limiting embodiment, the primary radar waves SI and the secondary radar waves S2 are radio frequency waves. The operation of a radar sensor 10 being known to those skilled in the art, it is not described in more detail here.

[32] As illustrated in Figure 2, in a non-limiting embodiment, the radar detection system 1 further comprises an electronic control unit 14 configured to analyze the secondary radar waves S2 processed by the receiver 101 and in deduce whether there is an object 3 in the external environment of the motor vehicle 2. It will be noted that the analysis can also be done directly in the radar sensor 10 in another non-limiting embodiment.

[33] As illustrated in Figure 2, in a non-limiting embodiment, the radar sensor 10 is disposed facing said light element 11, centered on the light element 11. It is disposed behind the element. light 11 along a through axis Ax (otherwise called transverse axis) of the motor vehicle 2 which passes through the light element 11, said through axis Ax extending in a direction opposite to the movement of the motor vehicle 2. In the example non-limiting taken from Figure 2, the motor vehicle 2 moves forward. In a nonlimiting embodiment, the radar sensor 10 is fixed to the light element 11. In a nonlimiting example, it is hung by means of fixing clips (not illustrated).

[34] As illustrated in Figure 2, the light element 11 comprises:

- at least one light source 110,

a plurality of layers 111 including a transparent layer 111a.

[35] The light source 110 is configured to emit light rays RI which are propagated by the transparent layer 111a. In a non-limiting embodiment, said at least one light source 110 is a semiconductor light source. In a non-limiting embodiment, said semiconductor light source forms part of a light emitting diode. By light-emitting diode is meant any type of light-emitting diode, whether in non-limiting examples of LEDs (“Light Emitting Diode”), OLED (“organic LED”), AMOLED (Active-Matrix-Organic LED), or FOLED (Flexible OLED). In another nonlimiting embodiment, said at least one light source 10 is a bulb with a filament. In a nonlimiting embodiment illustrated in FIG. 2, the luminous element 11 comprises two light sources 110. This nonlimiting embodiment is taken as a nonlimiting example in the remainder of the description. In a non-limiting embodiment illustrated in FIG. 2, the two light sources 110 are arranged on either side of the light element 11. Thus, they are offset relative to the light element 11 and therefore by in relation to its different layers.

[36] In a non-limiting embodiment, the transparent layer 111a is an optical element configured to propagate the light rays RI from the two light sources 110 and direct them towards another layer 111c. In a non-limiting variant embodiment illustrated in FIG. 2, the transparent layer 111a is a light guide.

[37] In a non-limiting embodiment, the transparent layer 111a is delimited by two layers 111 including a dark layer 111b. In a non-limiting embodiment, the other layer 111c which delimits the transparent layer 111a is a reflecting layer. Thus, in a non-limiting embodiment, the transparent layer 111a is configured to propagate the light rays RI from the two light sources 110 and project them through the reflecting layer 111c and also to project them directly through the pattern 13 described. later if such a pattern 13 is present.

[38] In a non-limiting embodiment, the dark layer 111b extends along the transparent layer 111a on the side opposite to the reflective layer 111c. The dark layer 111b is thus located behind the reflective layer 111c along the transverse axis Ax. The dark layer 111b is opaque or semi-opaque. In a non-limiting embodiment, the dark layer 111b is located opposite the radar sensor 10. The latter is thus located behind the dark layer 111b along the transverse axis Ax. In a first nonlimiting exemplary embodiment, the dark layer 111b is made of black polycarbonate. In a second nonlimiting exemplary embodiment, the dark layer 111b is a dark paint which covers the side of the transparent layer 111a opposite to the reflective layer 111c.

[39] The reflective layer 111c is a layer visible to an observer from outside the motor vehicle 2. The reflective layer 111c is thus located in front of the transparent layer 111a along the transverse axis Ax. In a nonlimiting embodiment, it extends along the transparent layer 111a. It is a reflective layer of light. It makes it possible to obtain a mirror effect. In non-limiting embodiments, the reflective layer 111c is made of indium, silicon oxide, titanium or any other reflective material. These materials make it possible to produce a reflective layer 111c which is sufficiently thin so that the radar waves S1, S2 from the radar sensor 10 can pass through. In a non-limiting variant embodiment, the reflective layer 111c is composed of a stack of layers of said reflective material. This is the case for silicon oxide in a non-limiting example.

[40] As illustrated in FIG. 4, in a non-limiting embodiment, the reflective layer 111c is configured to produce a pattern 13. In a non-limiting embodiment, the pattern 13 is produced by laser engraving. When the pattern 13 is cut by laser engraving, areas 130 are cut by laser engraving in the reflecting layer 111c. They let the light rays RI from the light sources 110 pass. The pattern 13 makes it possible to have a light signature when the two light sources 110 are on. In a non-limiting embodiment, the pattern 13 is a logo. The signature is thus the logo of the manufacturer of the motor vehicle 2 in a non-limiting example. Thus, the radar sensor 10 is placed behind the pattern 13 along the transverse axis Ax.

[41] As illustrated in FIG. 5, the plurality of layers 111 is crossed by the radar waves SI emitted by the radar sensor 10. A part of these radar waves SI is reflected on said plurality of layers 111 and produces reflections. SI ', otherwise called parasitic reflections or parasitic waves. The plurality of layers 111 of the luminous element 11 have different refractive indices of light n. Furthermore, the plurality of layers 111 of the luminous element 11 have substantially equal dielectric permittivities e. [42] Thus, the transparent layer 111a and the two layers which delimit it, namely the dark layer 111b and the reflective layer 111c in the non-limiting example taken, respectively exhibit refractive indices of light ni, n2, n3 different. This makes it possible to reflect the light rays RI from the light sources 110 and to orient them correctly at the desired location, here towards the layer visible from the outside of the motor vehicle 2, namely the reflective layer 111c in the non-limiting example. taken.

[43] Thus, the transparent layer 111a the dark layer 111b and the reflecting layer 111c in the non-limiting example taken, respectively have dielectric permittivities eΐ, e2, e3 which are substantially equal. In a nonlimiting embodiment, their dielectric permittivity eΐ, e2, e3 is between 2.4 and 3.5. This makes it possible to significantly reduce the reflections of the transmitted SI radar waves. There will be less reflections, called parasitic reflections, which interfere with the emission of said SI radar waves. Therefore, the detection of an object 3 will be more efficient. As illustrated in FIG. 5, the plurality of layers 111a, 111b, 111c, of the luminous element 11 is seen by the radar waves SI emitted as a single layer 111 which is therefore crossed by said radar waves SI. Therefore, there will only be a series of SI 'reflections on this layer. Indeed, as the layers 111a, 111b, 111c have dielectric permittivities eΐ, e2, e3 which are substantially equal, they are seen as the same medium by the radar waves SI. They will thus have the same propagation effect on the SI radar waves without these SI radar waves being disturbed by internal reflections which would be due to discontinuities in dielectric permittivities. This eliminates the need for discontinuities in dielectric permittivities.

[44] As can be seen in figure 5, there is also a series of reflections SI 'on the surface of the radar sensor 10. A part of its reflections start again in the direction opposite to the direction of the transverse axis A x , namely towards the outside of the motor vehicle 2, the other part is reflected again on the layer 111 considered to be unique.

[45] In order to obtain dielectric permittivities eΐ, e2, e3 which are substantially equal, in non-limiting embodiments, the transparent layer 111a will be composed of transparent polycarbonate, the dark layer 111b will be composed of black polycarbonate, and the reflective layer 111c will be composed of polycarbonate coated with indium (thin layers of a few tens of nanometers in a non-limiting embodiment). For a given material and color depending on the manufacturer and the manufacturing process, we can find different values of dielectric permittivity. Thus, in nonlimiting examples, for transparent polycarbonate, it is possible to have a dielectric permittivity eΐ of 2.5, 2.57 and 2.77. In nonlimiting examples, for black polycarbonate, it is possible to have a dielectric permittivity e2 of 2.49, 2.57 and 2.95. In a non-limiting example, for polycarbonate coated with indium, it is possible to have a dielectric permittivity e3 of 2.77. It will be noted that the thin layers of indium do not significantly change the dielectric permittivity of the polycarbonate (thin layers with a thickness of nanometers).

[46] In order to obtain substantially equal permittivities eΐ, e2, e3, in a nonlimiting embodiment, provision can be made to load the material with one or more layers 111, with polycarbonate microbeads referenced PC, the material of which is is more dense. Thus, the more dense the material of a layer, the more its dielectric permittivity e will increase.

[47] Of course, the description of the invention is not limited to the embodiments described above and to the field described above. Thus, in another nonlimiting embodiment, the transparent layer 111a is formed of prisms and / or micro-prisms. Thus, in another non-limiting embodiment, the transparent layer 111a can be delimited by two dark layers instead of a dark layer and a reflective layer. Thus, in another nonlimiting embodiment, the plurality of layers 111 of the luminous element 11 can comprise more than three layers. Thus, in another nonlimiting embodiment, the plurality of layers 111 can comprise at least one layer of air with the different layers other than said at least one layer of air of substantially equal dielectric permittivity. Thus, in a non-limiting variant embodiment, the transparent layer 111a is separated from the dark layer 111c by a layer of air, and / or from the reflecting layer 111c by another layer of air. The number of reflections will decrease with respect to a plurality of layers of different dielectric permittivity including one or more layers of air of dielectric permittivity also different from the other layers. Thus, in another nonlimiting embodiment, the two light sources 110 are arranged facing the dark layer 111b on a side opposite to the reflecting layer 111c. Thus, in another non-limiting embodiment, the radar detection system 1 is placed in a lighting device of the vehicle 2. In non-limiting examples, the lighting device is a headlight or a rear light. Thus, in a nonlimiting embodiment, the radar sensor 10 comprises a plurality of transmitters 100 and a plurality of receivers 101.

[48] Thus, the invention described has the following advantages in particular:

- It makes it possible to reduce the parasitic reflections of the radar waves SI emitted by the radar sensor 10 while continuing to propagate and direct the light rays RI from said at least one light source 110; thus this reduces the disturbance of the transmitted SI radar waves and the detection of a object 3 located in the external environment of the vehicle 2 is more precise, - it makes it possible to have for a luminous element 11 with a plurality of layers, reflections substantially similar to a luminous element 11 which comprises only one layer .

Claims

[Claim 1] A radar detection system (1) of a vehicle (2), said radar detection system (1) comprising:

- a radar sensor (10) configured to transmit / receive a plurality of radar waves (SI, S2),

- a luminous element (11) arranged opposite said radar sensor (10) and comprising at least one light source (110) configured to emit light rays (RI), and a plurality of layers (111) including a transparent layer ( 111a) configured to propagate said light rays (RI), characterized in that said layers (111) have substantially equal dielectric permittivities (e).

[Claim 2] A radar detection system (1) according to claim 1, wherein said transparent layer (111a) is a light guide.

[Claim 3] A radar detection system (1) according to any one of the preceding claims, wherein said transparent layer (111a) is delimited by two layers (111b, 111c) including a dark layer (111b).

[Claim 4] A radar detection system (1) according to the preceding claim, wherein said dark layer (111b) is disposed opposite said radar sensor (10).

[Claim 5] A radar detection system (1) according to any one of claims 3 or 4, wherein the other layer (111c) which delimits said transparent layer (111a) is a reflective layer.

[Claim 6] A radar detection system (1) according to any preceding claim, wherein one (111c) of the layers (111) other than the transparent layer (111a) is configured to provide a pattern (13).

[Claim 7] A radar detection system (1) according to any preceding claim, wherein said dielectric permittivities (e) of said layers (111) are between 2.4 and 3.5.

[Claim 8] A radar detection system (1) according to any preceding claim, wherein said radar sensor (10) is a millimeter wave or microwave or microwave radar sensor.

[Claim 9] A radar detection system (1) according to the preceding claim, wherein said radar sensor (10) operates at a radar frequency between 76GHz and 81GHz.