LIDAR SENSOR SYSTEM WITH IMPROVED SURFACE QUALITY

Description

[0001] The present invention relates to a sensor system comprising a LiDAR unit with a transmitter for laser light with a wavelength of 800 nm to 1600 nm and a receiver for light with a wavelength of 800 nm to 1600 nm, and a cover arranged such that IR light emitted and received by the LiDAR unit passes through the cover. The invention also relates to a manufacturing method for such a system, a vehicle having such a sensor system, and the use of a thermoplastic material for manufacturing covers for LiDAR sensors and / or LiDAR receivers.

[0002] Driver assistance systems such as emergency braking assistants, lane departure warning systems, traffic sign recognition systems, adaptive cruise control systems, and distance control systems are well known and used in today's vehicles. Environmental detection sensors, typically based on radar, LiDAR, ultrasonic, and camera sensors, are used to implement these functions. Stereo-optical camera systems and LiDAR sensors are particularly important for highly automated and autonomous driving because they are capable of providing high-resolution three-dimensional images of the vehicle's surroundings from near to far range. The substrate materials described in the present invention are particularly suitable for optical camera systems such as mono- and stereo-camera systems and LiDAR sensors. Furthermore, the substrate materials are suitable for radar sensors.

[0003] Optical camera systems are already being used in vehicle sensor technology, for example in lane departure warning systems. A major advantage of optical sensors is that they can provide a very precise image of the surroundings, i.e. the surroundings are not recorded at a specific point, but rather imaged over a large area. If the distance, for example to an object or another vehicle in front of the vehicle, is to be determined, multiple cameras such as stereo cameras are used instead of mono cameras. Instead of a rotating LiDAR system, two or more LiDAR sensors can be used. By capturing at least two images, a three-dimensional image can be calculated, for example using triangulation. This type of method therefore also enables distance measurements. Although optical distance measurement systems are very precise, their accuracy decreases with the distance to the respective object.As a sole sensor system, an optical camera system is dependent on the prevailing lighting conditions. Certain lighting conditions, such as backlighting, strong sunlight, twilight, or darkness, can significantly negatively impact the measurement results. Problems can also arise when detecting objects that lack strong contrast or contours. This can lead to incorrect interpretations of the surroundings.

[0004] For these reasons, multiple sensor systems are used. This allows digital camera images to be compared with information from other sensor systems, such as radar and, above all, LiDAR sensors. By combining this information, the software can create a representation of the environment that is as accurate as possible and correct potential false detections by individual sensor systems. Creating such a precise representation of the environment is essential for autonomous driving systems. Therefore, a cover made of a thermoplastic material must be suitable for several sensor types at the same time. For design reasons, it is particularly desirable to be able to create the respective cover from a single material rather than having to use multiple materials.

[0005] LiDAR (short for light detection and ranging) or LaDAR (laser detection and ranging) is a radar-related method for optical distance and speed measurement. Instead of the radio or microwaves used in radar, infrared laser beams are used. There are very different types of LiDAR systems, which differ, among other things, in their horizontal detection range (e.g., 70° to 360°), the laser type (e.g., scanning continuous wave laser or static pulse laser), and the sensor technology (e.g., mechanically rotating mirror or semiconductor electronics). The present invention also covers infrared cameras that are technically related to LiDAR but use their own infrared light source.

[0006] Components based on thermoplastic materials offer many advantages for automotive applications over conventional materials such as glass. These include increased shatter resistance and / or weight savings, which in the case of automobiles enable greater occupant safety in traffic accidents and lower fuel consumption. Finally, materials containing thermoplastic polymers allow for significantly greater design freedom due to their easier formability.

[0007] A cover made of a thermoplastic material is intended to conceal the LiDAR sensor and any optical camera system and also to protect the sensitive sensor electronics.

[0008] Lidar sensors and the use of the polycarbonate Makrolon 2405 with the color formulation 450601 are described in US 2012 / 0287417 A1. Further polycarbonate applications or compositions relating to lidar sensors are described in WO 2018 / 197398 A1.

[0009] Polycarbonate compositions containing glycerol esters or long-chain carboxylic acid esters, but without pentaerythritol esters, have already been described in the prior art. For example, WO 2010 / 090893 A1 discloses, in the experimental section on page 28, how polycarbonate pellets are sprayed with 400 ppm of Loxiol 3820 before adding powdered additives and extrusion.

[0010] US 2011 / 0129631 A1 discloses, in the experimental section in Table 1, polycarbonate compositions containing, among other ingredients, Loxiol 3820 as the mold release agent "MRA-1." Loxiol 3820 is identified in this publication as octyldodecyl stearate.

[0011] EP 2 810 978 A1 describes in Example 2, paragraph

[0049] that the polycarbonate Makrolon 2600 is extruded together with a mixture of carbon nanotubes (Baytubes C 150 P) and 2-octyldocecyl stearate (Loxiol 3820).

[0012] EP 0 732 360 A1 discloses in the experimental part in Tables 1, 3 and 5 polycarbonate compositions with Loxiol EP 218 ("E1", glycerol tristearate), Loxiol EP 12 ("E2", glycerol monostearate), Loxiol EP 32 ("E3", ester of C 16 alcohol with stearic acid) and Loxiol EP 47 ("E4", ester of a C 18 alcohol with behenic acid).

[0013] EP 0 205 192 A1 describes in the experimental part in Table 1 polycarbonate compositions with Resistat AF-101 ("B1", partial esters of C 18 - C 22 monobasic fatty acids and glycerol) and Rickemal S-100A ("B2", stearyl monoglyceride).

[0014] The present invention aims to provide a sensor system with a cover that exhibits lower LiDAR signal attenuation. The cover should exhibit good demolding properties, especially when the application field is two- or three-dimensionally shaped cover panels for LiDAR sensors. If the demolding properties are insufficient, adhesion or sticking of the molded part can lead to surface defects, which in turn attenuate the LiDAR signal. Since quality requirements in the sensor field are very high, it is important to prevent such defects.

[0015] According to the invention, the object is achieved by a sensor system according to claim 1 and a vehicle according to claim 12. The invention also relates to a method according to claim 11 and a use according to claim 13. Advantageous further developments are specified in the subclaims. They can be combined in any desired manner unless the context clearly indicates otherwise.

[0016] The sensor system includes: a LiDAR unit with a transmitter for laser light with a wavelength of 800 nm to 1600 nm and a receiver for light with a wavelength of 800 nm to 1600 nm and a cover which is arranged so that IR light emitted and received by the LiDAR unit passes through the cover.

[0017] The cover comprises a layer of a thermoplastic material, wherein the thermoplastic material contains a transparent thermoplastic polymer and a monoester of a monocarboxylic acid having 15-20 C atoms with glycerol or with a monoalcohol having ≥ 15 C atoms.

[0018] Furthermore, the thermoplastic material must be free from mono-, di-, tri- and tetraesters of stearic acid with pentaerythritol.

[0019] Surprisingly, it was found that replacing the usual pentaerythritol-based demolding agents, especially PETS, with the above-mentioned monoesters can simultaneously achieve good demolding behavior in injection molding and superior surface quality, i.e., lower attenuation of the LiDAR signal.

[0020] The term "free from" specifically means that no mono-, di-, tri-, or tetraesters of stearic acid with pentaerythritol have been intentionally added. Unwanted but technically unavoidable traces / impurities are then included in the term "free from."

[0021] Preferably, the thermoplastic material is generally free of mono-, di-, tri- and tetraesters of pentaerythritol.

[0022] The cover is preferably a molded part used in the front or rear area of ​​a vehicle, e.g., a bumper, radiator grille, front panel, or rear panel, in particular a front panel for a motor vehicle, but can also be a vehicle side panel. The cover can also be a roof or roof module for a motor vehicle.

[0023] It is equally possible for the cover to be a molded part that is used inside a vehicle. In this case, the system according to the invention can be used to detect control gestures by vehicle occupants.

[0024] The cover can be manufactured using an injection molding process. Polycarbonate, in particular, also exhibits excellent properties such as high heat resistance and high rigidity.

[0025] For example, the distance between the cover and the LiDAR unit can range from 1 cm to 20 cm.

[0026] A "system" is understood not only in the narrow sense of a package of mechanically connected individual parts, such as a device, but also more broadly as a mere combination of (merely) functionally connected individual parts. The LiDAR transmitter and receiver can be installed separately in the respective vehicle, and the cover can be provided for a desired location in the vehicle through which the pulses from the LiDAR sensor are to pass. However, it can also be a mechanically connected combination.

[0027] The LiDAR unit has a transmitter for laser light with a wavelength of 800 nm to 1600 nm. Due to the nature of laser light, this does not mean that the transmitter emits light at every wavelength between 800 nm and 1600 nm. Rather, it is sufficient if light of one wavelength, for example, 905 nm, is emitted. It is also possible to use multiple lasers with different wavelengths within this range.

[0028] The receiver is typically narrowband tuned to the emitted laser light, for example, 903 nm or 905 nm. It is also possible for the receiver to be tuned to a broader spectral window in the wavelength range from 800 nm to 1600 nm, or narrowband tuned to a variety of wavelengths.

[0029] The thermoplastic material contains a transparent thermoplastic polymer. "Transparent" in the context of the present invention means that the plastic has a light transmission (based on ASTM 1003 or ISO 13468; specified in % and illuminant D65 / 100) of at least 6%, more preferably at least 12%, and particularly preferably at least 23%. Furthermore, the turbidity (ASTM D1003: 2013) is preferably less than 3%, more preferably less than 2.5%, and particularly preferably less than 2.0%.

[0030] Examples of suitable thermoplastics are polycarbonate including copolycarbonate, polyester carbonate, polystyrene, styrene copolymers, aromatic polyesters such as polyethylene terephthalate (PET), PET-cyclohexanedimethanol copolymer (PETG), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyamide, cyclic polyolefins, poly- or copolyacrylates and poly- or copolymethacrylates such as poly- or copolymethyl methacrylates (such as PMMA) as well as copolymers with styrene such as transparent polystyrene acrylonitrile (PSAN), thermoplastic polyurethanes, polymers based on cyclic olefins (e.g. TOPAS ®< , a commercial product of Ticona). Here and elsewhere, when "polycarbonate" is mentioned, aromatic polycarbonate is preferably meant.

[0031] The thermoplastic material may also contain conventional additives such as flame retardants, antistatic agents, UV absorbers, stabilizers, and antioxidants. Suitable ultraviolet absorbers are benzotriazoles, triazines, benzophenones, and / or arylated cyanoacrylates. Phosphites, phosphonites, and phosphines are preferred stabilizers. Alkyl phosphates, such as mono-, di-, and trihexyl phosphate, triisoctyl phosphate, and trinonyl phosphate, may also be used. Phenolic antioxidants such as alkylated monophenols, alkylated thioalkylphenols, hydroquinones, and alkylated hydroquinones can be used as antioxidants.

[0032] The thermoplastic material preferably contains less than 0.1% by weight, and the compositions of the substrate layer are most preferably free of scattering additives, e.g., those based on acrylate, polyethylene, polypropylene, polystyrene, glass, aluminum oxide, and / or silicon dioxide. Furthermore, the composition most preferably contains less than 0.1% by weight, and is most preferably free of white pigments or similar pigments such as, for example, titanium dioxide, kaolin, barium sulfate, zinc sulfide, aluminum oxide, aluminum hydroxide, quartz powder, interference pigments, and / or pearlescent pigments, i.e., platelet-shaped particles such as mica, graphite, talc, SiO 2 , chalk, and / or titanium dioxide, coated and / or uncoated.

[0033] Furthermore, the thermoplastic material preferably contains less than 0.1 wt.%, and the composition is particularly preferably free of nanoparticulate systems such as metal particles and metal oxide particles. The composition preferably also contains less than 0.1 wt.%, and particularly preferably free of pigments based on insoluble pigments, as described, for example, in DE 10057165 A1 and WO 2007 / 135032 A2.

[0034] It is further advantageous for the thermoplastic material to contain 0 to ≤ 0.0005% by weight, based on the total weight of the composition, of infrared absorbers. The composition is preferably free of infrared absorbers. This is related to the attenuation of the LiDAR signal by infrared absorbers in the polymer. Infrared absorbers are particularly carbon black, LaB6, and molecules with a quaterylene structure.

[0035] Glycerol monostearate and / or 2-octyldodecyl stearate are particularly suitable as monoesters.

[0036] The thermoplastic material preferably contains no other monoesters than those of a monocarboxylic acid having ≥ 15 C atoms with glycerol or with a monoalcohol having ≥ 15 C atoms. According to a further embodiment, the monoester is present in a proportion of ≥ 0.01 wt.% to ≤ 0.6 wt.%, based on the total weight of the thermoplastic material of the described layer of the cover. It is further preferred that corresponding glycerol monoesters (for example, glycerol monostearate) are present in proportions of ≥ 0.01 wt.% to ≤ 0.06 wt.% and / or corresponding monoesters of a monocarboxylic acid with a monoalcohol having ≥ 15 C atoms, for example, 2-octyldodecyl stearate, are present in proportions of ≥ 0.15 wt.% to ≤ 0.6 wt.%.

[0037] According to another embodiment, the thermoplastic polymer is a polycarbonate. This includes polycarbonate and copolycarbonate. Thus, the polycarbonate can be an aromatic polycarbonate with a melt volume ratio (MVR) of 8 to 20 cm³ / (10 min), determined according to ISO 1133-1:2012-03 (300°C, 1.2 kg).

[0038] Particularly preferably, the thermoplastic material contains only aromatic polycarbonate as the thermoplastic polymer.

[0039] Aromatic polycarbonates particularly preferred according to the invention as component i) preferably have weight-average molecular weights Mw of 22,000 to 29,000 g / mol, although in principle weight-average molecular weights Mw of 10,000 to 50,000 g / mol, more preferably of 14,000 to 40,000 g / mol, and particularly preferably of 16,000 to 32,000 g / mol would also be suitable. The Mw values ​​are determined by gel permeation chromatography, calibrated against bisphenol A polycarbonate standards using dichloromethane as the eluent. The polycarbonates are preferably prepared by reactions of bisphenol compounds with carbonic acid compounds, in particular phosgene, or in the melt transesterification process with diphenyl carbonate or dimethyl carbonate.

[0040] Homopolycarbonates based on bisphenol A and copolycarbonates based on the monomers bisphenol A and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, e.g. Apec ®< from Covestro Deutschland AG, are particularly preferred.

[0041] According to a further embodiment, the cover attenuates the LiDAR signal only to the extent that the signal intensity of the IR light emitted and received by the LiDAR unit (determined by reflection from a smooth surface coated with TiO 2 -containing white paint at a distance of 3.2 m) is ≥ 80% of a reference intensity determined without the cover.

[0042] According to a further embodiment, the thermoplastic material has a static friction coefficient, determined as described in EP 1 377 812 B1, of ≤ 0.37. Preferred sliding friction coefficients, also determined as described in EP 1 377 812 B1, are ≤ 0.37.

[0043] According to a further embodiment, the system further comprises a camera for visible light with a wavelength of 380 nm to 780 nm, wherein visible light received by the camera passes through the cover. The camera records light in the wavelength range from 380 nm to 780 nm, although this wavelength range is not intended to be exhaustive. This wavelength range can be broader, for example up to 800 nm, 900 nm, 1000 nm, or 1100 nm. Visible light cameras often have an upstream IR filter. If this is removed, some models can record images in the wavelength range up to 1100 nm. In a further embodiment, the camera therefore has no or a limited infrared filter.

[0044] The camera is preferably a video camera to provide information to the vehicle's driver assistance system or autonomous driving system in real time, if possible. The camera is also preferably a stereo camera.

[0045] According to a further embodiment, the cover further comprises a layer containing dyes and / or colorants are contained in the thermoplastic material, so that the cover has a light transmission Ty in the range from 380 to 780 nm of ≥ 3% to ≤ 25%, determined according to DIN ISO 13468-2:2006 (D65, 10°), and the colorants are at least one green and / or one blue colorant and at least one red and / or violet colorant.

[0046] This design makes the cover appear dark to black to the observer, and electronic elements behind it, such as sensors or cameras, are barely noticeable or not noticeable at all. This is known as the "black panel" effect and allows automotive designers greater freedom in designing aesthetically pleasing car exteriors. The colorants are preferably those that exhibit little or no absorption in the infrared range, especially in the wavelength range of the LiDAR laser(s).

[0047] Preferably, the cover has a transmission for light in the range from 380 nm to 1100 nm of ≥ 40%, determined according to DIN ISO 13468-2:2006 (based on this standard, wavelength range was used as stated).

[0048] The transmissions given are averaged transmissions (arithmetic mean), averaged over all wavelengths in the respective range.

[0049] In one embodiment, the green / blue colorant is selected from the formulas (1), (2a-c), (3), (4a), (4b), (5), (6), (7) and / or (8) and the red / violet colorant is selected from the formulas (9), (10), (11), (12), (13), (14a), (14b) and / or (15):

[0050] The colorant of formula (1) is known under the name Macrolex Green 5B from Lanxess Deutschland GmbH, Color Index number 61565, CAS number: 128-90-3, and is an anthraquinone dye.

[0051] Colorants of formulas (2a), (2b) and (2c) are known, among other things, under the name Macrolex Green G (Solvent Green 28).

[0052] Blue colorants used according to this embodiment are colorants of the formulas (3) and / or (4a / 4b) and / or (SalSb): available under the name "Keyplast Blue KR", CAS number 116-75-6, where Rc and Rd independently of one another represent a linear or branched alkyl radical or halogen, preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl, or Cl, more preferably methyl, Cl and particularly preferably Cl, n independently of the respective R represents a natural number between 0 and 3, where the radical for n=0 is hydrogen.

[0053] In a preferred embodiment, Rc and / or Rd are Cl and are located in the ortho and / or para positions to the carbon atoms bearing the amine functionalities, such as diorthochloronaphthalino, di-ortho, mono-para-chloronaphthalino, and mono-orthonaphthalino. Furthermore, in a preferred embodiment, Rc and Rd each represent a tert-butyl radical, which is preferably located in the meta position to the carbon atoms bearing the nitrogen functionalities.

[0054] In a particularly preferred embodiment, n=0 in all rings, so that all Rc and Rd = H.

[0055] The radicals R(5-20) are each independently hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl, fluorine, chlorine, bromine, sulfone, CN.

[0056] Preferably, R(5-20) is the same in all positions. More preferably, R(5-20) is H in all positions. In an alternative embodiment, R(5-20) is Cl in all positions.

[0057] M is preferably aluminum (with R=H: aluminum phthalocyanine, CAS: 14154-42-8). Nickel (with R=H: nickel phthalocyanine, CAS: 14055-02-8), cobalt (with R=H: cobalt phthalocyanine, CAS: 3317-67-7), iron (with R=H: iron phthalocyanine, CAS: 132-16-1), zinc (with R=H: zinc phthalocyanine, CAS: 14320-04-08), copper (with R=H: copper phthalocyanine, CAS: 147-14-8; with R=H and Cl: polychlorocopper phthalocyanine, CAS: 1328-53-6; with R=Cl: hexadecachlorophthalocyanine, CAS: 28888-81-5; with R=Br: hexadecabromophthalocyanine, CAS: 28746-04-5), manganese (with R=H: manganese phthalocyanine, CAS: 14325-24-7).

[0058] Particularly preferred is the combination of M = Cu and R = H for all positions. Thus, a compound of structure (5b) with M=Cu and R(5-20)=H is available as Heliogen®< Blue K 6911D or Heliogen®< Blue K 7104 LW from BASF AG, Ludwigshafen.

[0059] Compounds of structure (5a) are available, for example, as Heliogen ®< Blue L 7460 from BASF AG, Ludwigshafen.

[0060] Furthermore, the following can be used as blue colorants: Colorants of formula (6), available under the name "Macrolex Blue 3R Gran" and / or colorants of formula (7), available under the name "Macrolex Blue RR" (CAS 32724-62-2; Solvent Blue 97; CI 615290),

[0061] Furthermore, the following can be used as a blue colorant: where R1 and R2 independently of one another represent a linear or branched alkyl radical or halogen, preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl or Cl, more preferably methyl, Cl and particularly preferably Cl, n represents a natural number between 0 and 4.

[0062] In a particularly preferred embodiment, n=0 in all rings, so that all R1 and R2 = H.

[0063] Colorants of this structure (8) are commercially available under the Paliogen Blue series from BASF AG.

[0064] When using colorants of structure (8), particular preference is given to pigments which have a bulk volume (determined according to DIN ISO 787-11:1995-10) of 2 l / kg - 10 l / kg, preferably 3 l / kg - 8 l / kg, a specific surface area (determined according to DIN 66132:1975-07) of 5 m 2 < / g - 60 m 2 < / g, preferably 10 m 2 < / g - 55 m 2 < / g, and a pH value (determined according to DIN ISO 787-9) of 4 - 9.

[0065] The preferred red colorant is a colorant of formula (9), available under the name "Macrolex Red 5B", with the CAS number 81-39-0:

[0066] Furthermore, colorants of the formulas (10) with the CAS number 20749-68-2 (also: 71902-17-5) and (11) with the CAS number 89106-94-5 can be used:

[0067] Preferred violet colorants are colorants of the formulas (12) with the CAS number 61951-89-1, (13), available under the name "Macrolex Violet B" from Lanxess AG, with the CAS number 81-48-1, or (14a / 14b): wherein R is selected from the group consisting of H and p-methylphenylamine residue; preferably R = H; where Ra and Rb independently of one another represent a linear or branched alkyl radical or halogen, preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl, or Cl, more preferably methyl, Cl and particularly preferably Cl, n independently of the respective R represents a natural number between 0 and 3, where the radical for n=0 is hydrogen.

[0068] In a preferred embodiment, Ra and / or Rb are Cl and are located in the ortho and / or para positions to the carbon atoms bearing the amino functionalities, such as diorthochloronaphthalino, di-ortho, mono-para-chloronaphthalino, and mono-orthonaphthalino. Furthermore, in a preferred embodiment, Ra and Rb each represent a tert-butyl radical, which is preferably located in the meta position to the carbon atoms bearing the nitrogen functionalities.

[0069] In a particularly preferred embodiment, n=0 in all rings, so that all Ra and Rb = H.

[0070] Furthermore, colorants corresponding to formula (15), available under the name "Macrolex RedViolet R", CAS number 6408-72-6, can be used:

[0071] According to a further embodiment, the thermoplastic material comprises the following components: at least 99 wt.%, based on the total weight of the material, aromatic polycarbonate with a melt volume rate MVR of 15 to 20 cm3 / (10 min), determined according to ISO 1133-1:2012-03 (300°C, 1.2 kg); colorant of formula (2a), (2b) and / or (2c); colorant of formula (5b) with M = Cu and R(5-20) = H; colorant of formula (10); where the sum of the total colorants used is ≥ 0.017 wt.% to ≤ 0.057 wt.%, based on the total weight of the material.

[0072] According to a further embodiment, the thermoplastic material comprises a yellow and / or orange colorant of the formulas (16), (17), (18), (19), (20) or a mixture of at least two thereof:

[0073] The yellow colorants used are colorants of the formulas (16), available under the name "Macrolex Yellow 3G" with the CAS number 4702-90-3, and / or (17), available under the name "Macrolex Orange 3G" (CAS number 6925-69-5, CI 564100):

[0074] Furthermore, it is possible to use colorants of the formulas (18), available under the name "Oracet Yellow 180" with the CAS number 13676-91-0, (19) with the CAS number 30125-47-4 and / or (20), available under the name "Oracet Orange 220; Solvent Orange 116" with the CAS number 669005-94-1.

[0075] In principle, however, additional colorants can be used in addition to the colorants described above. Preferred colorants are Heliogen Green types (such as Heliogen Green K 8730; CAS 1328-53-6; Pigment Green 7; CI 74260).

[0076] Particularly preferred are Green G (2a, b, c), Heliogen Green and Heliogen Blue (5a, 5b), Paliogen Blue (8) in one group and Macrolex Red EG (10) and Amaplast Violet PK (14a, 14b) and M. Violet B (13) in the other group in combination with yellow colorants.

[0077] Exemplary colorant combinations are listed below, whereby the weight percentages are based on the total weight of the thermoplastic material and may deviate by ± 10% of the stated value: Macrolex Violet 3R (12) and Macrolex Green 5B (1), each 0.1 wt% of both of these colorants; Macrolex Red EG (10) 0.004 wt%, Macrolex Violet 3R (12) 0.001 wt% and Heliogen Blue K6911 [(5b) with M=Cu and R(5-20)=H] 0.0024 wt%; Oracet Yellow 180 (18) 0.0004 wt%, Macrolex Red EG (10) 0.0045 wt% and Macrolex Green 5B (1) 0.0046 wt%; Macrolex Red EG (10) 0.0007 wt%, colorants of structure (14a) and / or (14b) 0.0014 wt% and Paliogen Blue L6385 (8) 0.0030 wt%; Colorants of structure (11) 0.0015 wt%, Macrolex Violet B (13) 0.0012 wt% and Heliogen Blue K6911 [(5b) with M=Cu and R(5-20)=H] 0.0010 wt% and 0.0018 wt%, Macrolex Blue RR (7) 0.0032 wt% and Macrolex Red EG (10) 0.0031 wt%.

[0078] According to a further embodiment, the cover further comprises a topcoat layer. This can serve to improve scratch and weather resistance. The coating systems particularly suitable for this purpose, which are used, for example, for polycarbonate sheets in the construction sector, for polycarbonate headlight covers, or also in the field of polycarbonate automotive glazing, can be roughly divided into three categories: (a) Thermally curing coating systems based on a polysiloxane varnish, which can be single-layer or multi-layer (with only an adhesion-promoting primer layer between the substrate and the polysiloxane topcoat). These are described, among others, in US 4,278,804, US 4,373,061, US 4,410,594, US 5,041,313 and EP-A-1 087 001. One variant is the use of the adhesion primer required for the siloxane-based topcoat as a UV protection primer by adding UV absorber to it and applying it in a thicker layer. (b) Thermally curing multi-layer systems with a UV protection primer and a topcoat based on a polysiloxane varnish. Suitable systems are known, for example, from US 5,391,795 and US 5,679,820. (c) Likewise, UV-curing coating systems can be used, e.g.Based on acrylate, urethane acrylate, or acrylosilane, which may contain fillers to improve scratch resistance, provide sufficient weather protection due to their wider application thickness range. Such systems are known and are described, among others, in US 3,707,397 or DE 69 71 7959, US 5,990,188, US 5,817,715, US 5,712,325, and WO 2014 / 100300.

[0079] In a further embodiment, the topcoat used in the topcoat layer is a UV-curing topcoat, as already described above under point c).

[0080] In a further embodiment, the topcoat layer contains an organo-modified silane or its reaction product.

[0081] According to a further embodiment, an adhesion promoter layer (primer layer) is present between the topcoat layer and the thermoplastic material. A preferred combination is an adhesion-promoting UV protection primer based on polymethyl methacrylate with dibenzoylresorcinol as a UV absorber and a polysiloxane topcoat with a silylated UV absorber. Both layers, i.e., primer and topcoat together, provide the UV protection.

[0082] According to a further embodiment, the cover further comprises: an anti-reflective layer, an anti-fog layer, an anti-dust layer, a layer improving media resistance, a layer improving scratch resistance, or a combination thereof. Examples of anti-fog and anti-dust coatings (anti-dust coatings) are layers obtained by flame silicating. Anti-reflective layers include all single- or multi-layer coating structures that have a low-refractive index layer (nD <1.5) as the outer layer. The use of the coating used on the outside can also improve the following properties, among others: media resistance, scratch resistance, reduced reflection (anti-reflective), and a slight anti-dust effect.

[0083] The method for producing a system according to the invention comprises the steps: Providing a cover produced at least partially by injection molding, as defined above; providing a LiDAR unit with a transmitter for laser light having a wavelength of 800 nm to 1600 nm and a receiver for light having a wavelength of 800 nm to 1600 nm; arranging the cover such that IR light emitted and received by the LiDAR unit passes through the cover.

[0084] Another aspect of the invention is a vehicle comprising a system according to the invention. The system can be mounted not only on motor vehicles, but also on other means of transport and locomotion, such as drones, airplanes, helicopters, or rail vehicles, all of which are subsumed under the term "vehicles" according to the invention. This also includes (semi-)autonomous machines that are not necessarily used for locomotion, such as robots, harvesters, and the like.

[0085] The invention further relates to the use of a thermoplastic material for producing covers for LiDAR sensors and / or LiDAR receivers, wherein the thermoplastic material contains a transparent thermoplastic polymer and a monoester of a monocarboxylic acid having ≥ 10 C atoms with an alcohol having ≥ 3 C atoms and with the proviso that the thermoplastic material is free of mono-, di-, tri- and tetraesters of stearic acid with pentaerythritol and wherein the monoester is a monoester of a monocarboxylic acid having ≥ 15 C atoms with glycerol or with a monoalcohol having ≥ 15 C atoms.

[0086] According to one embodiment of the use, the thermoplastic polymer is an aromatic polycarbonate. For further embodiments and definitions, reference is made to the explanations regarding the system according to the invention to avoid repetition. These are equally applicable to the use according to the invention. Examples

[0087] The present invention is further illustrated by the following examples, but is not limited thereto. The determination methods described here apply to all corresponding quantities in the present description of the invention, unless otherwise stated. Components

[0088] PC-1: Linear bisphenol A homopolycarbonate with phenol-based end groups with a melt volume rate MVR of 19 cm 3 / 10 min (measured at 300 °C and 1.2 kg load according to ISO 1133-1:2011), PC-2: Linear bisphenol A homopolycarbonate with phenol-based end groups with a melt volume rate MVR of 12 cm 3 / 10 min (measured at 300 °C and 1.2 kg load according to ISO 1133-1:2011), PC-3:Linear bisphenol A homopolycarbonate with phenol-based end groups with a melt volume rate MVR of 6 cm 3 / 10 min (measured at 300 °C and 1.2 kg load according to ISO 1133-1:2011), A: Pentaerythritol tetrastearate, CAS 115-83-3 (Glycolube P from Lonza GmbH Germany), B: Glycerol monostearate, CAS 31566-31-1 (Dimodan Hab Veg from Danisco Deutschland GmbH, Germany), C: 2-Octyldodecyl stearate, CAS 22766-82-1 (Loxiol 3820 from Emery Oleochemicals Europe, Düsseldorf, Germany), D: Pentaerythritol distearate, CAS 13081-97-5 (Struktol VPEDS from Struktol Company of America; Ohio USA). Compounding

[0089] The materials were compounded on a KraussMaffei Berstorff ZE25 twin-screw extruder at a barrel temperature of 260 °C and a melt temperature of approximately 280 °C, respectively, and a speed of 100 rpm. Additives A to D were mixed with powdered polycarbonate PC-3 in the amounts specified below and then compounded with the polycarbonates PC-1 or PC-2. Measuring LiDAR signal strength

[0090] To reduce stray light signals, the sensor head of the LiDAR sensor was shielded on the side facing away from the measurement path. Only lasers 1, 3, 5, 7, 8, 10, 12, and 14 were used. Furthermore, the field of view (FOV) of the sensor in the sensor interface was limited to 20° (350°-10°). A smooth white surface painted with TiO2-containing paint served as the reflection surface. The wall was located 3.2 m from the LiDAR sensor.

[0091] The test samples were tested using a sample holder parallel to the LIDAR, with the back of the sample positioned approximately 15 mm in front of the LiDAR sensor, so that both the output signal and the reflected input signal had to penetrate the wall thickness of the test plate. The evaluation was performed using the "VeloView" software from the manufacturer of the LiDAR sensor, Velodyne. The mean of the measured intensities of a sample was determined. This sample mean was divided by the mean of the reference measurement (air) to determine the relative intensity.

[0092] The measured intensities of the recaptured laser signal ranged from 0% to 100%. The lower the attenuation (weakening) of the signal, i.e., the higher the measured signal intensity, the more suitable the coverage is for LiDAR-based sensor applications in the automotive sector. The intensities measured in the examples are documented in the column "LIDAR signal relative to air value in %." Measurement of static friction

[0093] The friction coefficients were determined using a modified Arburg 370S-800-150 injection molding machine. The method is described in EP 1 377 812 B1. Static friction is the friction coefficient derived from the force required to set relatively stationary bodies (punch / test specimen) in motion (threshold value).

[0094] The static friction coefficient is defined as follows: FR = µ x FN or, rearranged for µ, µ = FR / FN (FN = normal force, FR = friction force, µ = friction coefficient).

[0095] For circular motion the following relationship applies: FR = M d / rm (M d = torque, rm = mean radius of the friction surface (ring surface)) and M d / rm = µ x FN and, rearranged for µ, µ = M d / (rmx FN ).

[0096] A disc-shaped test specimen with an outer diameter of 92 mm and a thickness of 2.6 mm was manufactured in a friction coefficient tool. This specimen had a 5 mm high and 3 mm wide ridge on the outer edge, which contained shallow recesses similar to a timing belt pulley, through which the torque is transferred from the tool to the test specimen.

[0097] It allows the direct determination of the coefficient of static friction on a disc-shaped test specimen immediately after it has solidified. The relationship here is that the friction force is proportional to the torque. When the mold is opened, a punch connected to a torque transducer moves against the molded part (friction partner) with a defined normal force FN. The test specimen is held on the other side of the molded part and rotated. The coefficient of static friction between the punch and test specimen is determined using the torque measured on the punch. Since friction is caused by the unevenness of the surfaces sliding against each other (jamming), the punch was designed with an average surface roughness Ra = 0.05 µm.

[0098] The materials were melted on an injection molding machine and injected at a melt temperature of 280 °C into a closed friction coefficient mold with a mold wall temperature of 80 °C. The mold was held under holding pressure of 550 bar for 15 s. After a residual cooling time of 20 s, the mold was opened slightly, and the static and dynamic friction coefficients were determined.

[0099] The results are listed in the table below. Examples marked with "V" are comparative examples, and examples marked with "E" are inventive. 1V 2V 3V 4E 5E 6E 7E 8V 9V 10V 11E Composition [wt%] PC-1 95 95 95 95 95 95 95 95 95 PC-2 95 95 PC-3 4,8 4,7 4,6 4,98 4,96 4,85 4,7 4,97 4,96 4,6 4,96 A 0,2 0,3 0,4 0,4 B 0,02 0,04 0,04 C 0,15 0,3 D 0,03 0,04 Results LiDAR signal strength [%] 78,7 78,4 73,7 80,8 80,2 82,6 80,7 81,9 82,6 78,4 80,4 Coefficient of static friction 0,32 0,29 0,27 0,37 0,33 0,29 0,25 0,44 0,43 0,27 0,27 coefficient of sliding friction 0,35 0,33 0,30 0,37 0,34 0,31 0,25 0,44 0,43 0,30 0,27

[0100] It can be seen that only the compositions according to the invention simultaneously deliver a high residual signal strength and the required demolding effect, expressed as sliding and static friction coefficients. Compositions with other demolding agents did not exhibit the desired combination of properties.

Claims

1. Sensor system comprising - a LiDAR unit having a transmitter for laser light having a wavelength of 800 nm to 1600 nm and a receiver for light having a wavelength of 800 nm to 1600 nm and - a cover arranged such that IR light transmitted by the LiDAR unit and received thereby passes through the cover, characterized in that the cover comprises a layer of a thermoplastic material, wherein the thermoplastic material contains a transparent thermoplastic polymer and a monoester of a monocarboxylic acid having ≥ 10 C atoms with an alcohol having ≥ 3 C atoms, wherein the monoester is a monoester of a monocarboxylic acid having 15 to 20 C atoms with glycerol or with a monoalcohol having ≥ 15 C atoms, with the proviso that the thermoplastic material is free from mono-, di-, tri- and tetraesters of stearic acid with pentaerythritol.

2. System according to Claim 1, wherein the monoester is present in a proportion of ≥ 0.01% by weight to ≤ 0.6% by weight based on the total weight of the thermoplastic material.

3. System according to either of the preceding claims, wherein the transparent thermoplastic polymer is an aromatic polycarbonate.

4. System according to any of the preceding claims, wherein the cover attenuates the LiDAR signal only to the extent that the signal intensity of IR light transmitted by the LiDAR unit and received again thereby, determined by reflection from a smooth surface painted with TiO2-containing white paint at a distance of 3.2 m, is ≥ 80% of a reference intensity determined without the cover.

5. System according to any of the preceding claims, wherein the thermoplastic material has a coefficient of static friction, determined as described in EP 1 377 812 B1, of ≤ 0.37.

6. System according to any of the preceding claims, further comprising a camera for visible light having a wavelength of 380 nm to 780 nm, wherein visible light received by the camera passes through the cover.

7. System according to any of the preceding claims, wherein the cover further comprises a layer containing dyes and / or the thermoplastic material contains colourants with the result that the cover has a light transmission Ty in the range of 380 to 780 nm from ≥ 3% to ≤ 25% determined according to DIN ISO 13468-2:2006 (D65, 10°) and the colourants comprise at least one green and / or blue colourant and at least one red and / or purple colourant.

8. System according to any of the preceding claims, wherein the cover further comprises a topcoat layer.

9. System according to Claim 9, wherein an adhesion promoter layer is present between the topcoat layer and the thermoplastic material.

10. System according to any of the preceding claims, wherein the thermoplastic material of the layer described in Claim 1 contains only aromatic polycarbonate as the transparent thermoplastic polymer and no monoesters of monocarboxylic acids other than those mentioned.

11. Process for producing a system according to any of the preceding claims comprising the steps of: - providing a cover as defined in any of the preceding claims at least partially produced by injection moulding; - providing a LiDAR unit having a transmitter for laser light having a wavelength of 800 nm to 1600 nm and a receiver for light having a wavelength of 800 nm to 1600 nm; - arranging the cover such that IR light transmitted by the LiDAR unit and received thereby passes through the cover.

12. Vehicle comprising a system according to any of Claims 1 to 10.

13. Use of a thermoplastic material for producing covers for LiDAR sensors and / or LiDAR receivers, characterized in that the thermoplastic material contains a transparent thermoplastic polymer and a monoester of a monocarboxylic acid having ≥ 10 C atoms with an alcohol having ≥ 3 C atoms, with the proviso that the thermoplastic material is free from mono-, di-, tri- and tetraesters of stearic acid with pentaerythritol and wherein the monoester is a monoester of a monocarboxylic acid having 15-20 C atoms with glycerol or with a monoalcohol having ≥ 15 C atoms.

14. Use according to Claim 13, wherein the transparent thermoplastic polymer is an aromatic polycarbonate.