IR-TRANSPARENT SENSOR AND CAMERA SYSTEM FOR MOTOR VEHICLES

Abstract

A sensor system comprises a LiDAR unit, a camera for visible light and a cover through which light arrives at the LiDAR unit and the camera. The cover comprises a layer containing dyes.

The light transmission of the cover in the range from 380 nm to 780 nm is 3% to 25% and in the range from 380 nm to 1100 nm is 40% or more. The attenuation of the LiDAR signal by the cover is such that at least 65% of the original signal intensity reaches the LiDAR detector.

The layer containing dyes contains a composition comprising i) at least 70% by weight of a transparent thermoplastic polymer, ii) at least one green and/or red dye and iii) at least one red and/or violet dye.

The product of the sum of the weight % fractions of dyes ii) and iii) and the thickness of the layer containing dyes is 0.041 to 0.12 wt % mm.

Finally, the composition contains 0% to 0.0005% by weight of IR absorbers.

Claims

1.-15. (canceled)

16. A 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; a camera for visible light having a wavelength of 380 nm to 780 nm and a cover arranged such that IR light transmitted by the LiDAR unit and received thereby and visible light received by the camera passes through the cover, wherein the cover comprises a layer containing dyes, wherein 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, the cover has a transmission for light in the range of 380 nm to 1100 nm of ≥40% determined according to DIN ISO 13468-2:2006, the cover attenuates the LiDAR signal only to the extent that the signal intensity of the IR light transmitted by the LiDAR unit and re-received thereby (determined by reflection from a smooth surface painted with TiO.sub.2-containing white paint at a distance of 3.2 m) is ≥65% of a reference intensity determined without the cover and in that the layer containing dyes comprises a thermoplastic composition comprising the following components: i) at least 70 wt % based on the total weight of the composition of a transparent thermoplastic polymer; ii) at least one green and/or blue colourant; iii) at least one red and/or violet colourant; wherein the product of the sum of the weight percent fractions (based on the total weight of the composition) of the colourants ii) and iii) and the thickness of the layer containing dyes is ≥0.041 wt % mm to ≤0.12 wt % mm and wherein the composition contains 0 to ≤0.0005 wt % based on the total weight of the composition of infrared absorbers.

17. The system as claimed in claim 16, wherein the component ii) is selected from the formulae (1), (2a-c), (3), (4a), (4b), (5), (6), (7) and/or (8) and the component iii) is selected from the formulae (9), (10), (11), (12), (13), (14a), (14b) and/or (15): ##STR00015## ##STR00016## wherein Rc and Rd independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents a natural number between 0 and 3, ##STR00017## where the radicals R(5-20) independently of one another represent hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl, fluoro, chloro, bromo, sulfone or CN and M is aluminum, nickel, cobalt, iron, zinc, copper or manganese, ##STR00018## wherein R1 and R2 independently of one another represent a linear or branched alkyl radical or halogen, n is a natural number between 0 and 4, ##STR00019## ##STR00020## wherein R is selected from the group consisting of H and p-methylphenylamine radical, ##STR00021## wherein Ra and Rb independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents a natural number between 0 and 3, ##STR00022##

18. The system as claimed in claim 16, wherein the thermoplastic composition of the layer containing dyes comprises the following components: at least 99 wt % based on the total weight of the composition of aromatic polycarbonate having a melt volume rate MVR of 15 to 20 cm.sup.3/(10 min) determined according to ISO 1133-1:2012-03 (300° C., 1.2 kg); colourants of formula (2a), (2b) and/or (2c); colourants of formula (5b) where M=Cu and R(5-20)=H; colourants of formula (10); wherein the sum of the colourants employed in total is ≥0.017 wt % to ≤0.057 wt % based on the total weight of the composition.

19. The system as claimed in claim 16, wherein the thermoplastic composition of the layer containing dyes comprises a yellow and/or orange-coloured dye of formulae (16), (17), (18), (19), (20) or a mixture of at least two thereof: ##STR00023## ##STR00024##

20. The system as claimed in claim 16, wherein the camera has a limited infrared filter, if any.

21. The system as claimed in claim 16, wherein the cover further comprises a topcoat layer.

22. The system as claimed in claim 21, wherein the topcoat layer contains an organomodified silane or a reaction product thereof.

23. The system as claimed in claim 21, wherein an adhesion promoter layer is present between the topcoat layer and the layer containing dyes.

24. The system as claimed in claim 21, wherein the topcoat used in the topcoat layer is a UV-curable topcoat.

25. The system as claimed in claim 21, wherein a further layer is present on the side of the layer containing dyes that is opposite the topcoat layer.

26. The system as claimed in claim 25, wherein the further layer is an antireflection layer, an anti-condensation layer, an anti-dust layer, a layer improving media resistance or a layer improving scratch resistance or a combination thereof.

27. The system as claimed in claim 16, wherein in the cover the layer containing dyes has a thickness of ≥0.15 mm to ≤5 mm.

28. The system as claimed in claim 16, wherein the cover comprises a plurality of layers containing dyes which may be identical or different.

29. The system as claimed in claim 16, wherein the cover further comprises a layer of an aromatic polycarbonate which does not contain green, blue, red and/or violet colourants.

30. A vehicle comprising a system as claimed in claim 16.

Description

EXAMPLES

[0134] The present invention is elucidated in detail by the examples which follow, but without being limited thereto.

[0135] Materials Used

[0136] PC1: Linear bisphenol A polycarbonate comprising end groups based on 4-butylphenol having an MVR of 19 cm.sup.3/(10 min) measured at 300° C. and a loading of 1.2 kg according to ISO 1033 and containing 0.40% by weight of pentaerythritol tetrastearate as a demoulding agent.

[0137] A: Macrolex Green G: Solvent Green 28; CAS Number 4851-50-7 from Lanxess AG, Leverkusen. Conforms to formulae (2a), (2b) or (2c).

[0138] B: Heliogen Blue K7104: Pigment Blue 15:4; CAS Number 147-14-8 from BASF SE, Ludwigshafen. Conforms to structure (5b) where M=Cu and R(5-20)=H.

[0139] C: Macrolex Yellow 3G: Solvent Yellow 93; CAS Number 4702-90-3 from Lanxess AG, Leverkusen. Conforms to structure (16).

[0140] D: Macrolex Red EG: Solvent Red 135; CAS Number 20749-68-2 from Lanxess AG, Leverkusen. Conforms to structure (10).

[0141] PC2: Composition containing 99.8% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. and a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol and containing 0.1% by weight of Macrolex Violet 3R (conforms to structure (12)) and 0.1% by weight of Macrolex Green 5B (conforms to structure (1)).

[0142] PC3: Polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. and a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol and containing UV absorbers and demoulding agents; the colourant content was <0.0002% by weight.

[0143] PC4: Polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. and a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol and containing UV absorbers and demoulding agents; the colourant content was <0.0002% by weight.

[0144] SHP 470 FT 2050 (primer)/AS 4700 F (topcoat): Silicone-based scratch resistant coating from Momentive Performance Materials, USA. The use of primer and topcoat was carried out according to manufacturer's instructions. If the following examples refer to the AS 4700 F coating, this was always employed together with this primer.

[0145] Employed LiDAR Sensor

[0146] A Velodyne Ty Puck VLP 16 LiDAR sensor was employed. Said sensor operates in the wavelength range from 895 to 915 nm (tolerance range). The nominal wavelength, i.e. actual operating wavelength, of the 16 lasers is 903 nm.

[0147] The essential characteristics of this sensor include:

[0148] Vertical detection angle −15° to +15° with 2° spacing between scanning planes; horizontal detection angle 360°. The software includes a multibeam function with 16 beams for minimizing shadow effects. Horizontal resolution of the laser system is 0.1° to 0.4° depending on rotational velocity. The rotational velocity of vertical detection is adjustable between 5 to 20 Hz. At a data rate of 2 Mbyte/sec, 300 000 points/second are detected. The measurement accuracy achieved is about +/−3 cm, corresponding to 1 sigma. The detectable measuring distance is between 1 mm to 100 metres. The energy requirement of the sensor system is 8 watts of electrical power, corresponding to 0.7 A at 12 volts. The overall dimensions of the sensor are: diameter 100 mm and height 65 mm.

[0149] Method of Measurement

[0150] To reduce the scattered-light signals, the sensor head of the LiDAR sensor was shielded on the side 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°. The reflection surface used was a smooth white surface coated with TiO.sub.2-containing paint. The wall was at a distance of 3.2 m from the LiDAR sensor.

[0151] The test specimens were tested using a sample holder parallel to the LiDAR, wherein the back side of the sample was arranged about 15 mm in front of the LiDAR sensor so that both the output signal and the reflected input signal had to pass through the wall thickness of the test sheet. Evaluation was performed using “VeloView” software from Velodyne, the manufacturer of the LiDAR sensor. The average value of the intensities measured for a sample was determined. This average sample value was divided by the average value of the reference measurement (air) to determine the relative intensity.

[0152] The measured intensities of the re-recorded laser signal were between 0% and 100%. The lower the attenuation (weakening) of the signal, i.e. the higher the intensity of the signal measured, the more suitable the cover for LiDAR-assisted sensor applications in the automotive sector. The intensities measured in the examples are documented in the column “LiDAR signal based on air value in %”.

[0153] The permeability of the respective sheet to IR radiation in the range from 800 to 1600 nm was determined according to DIN ISO 13468-2:2006. The light transmission in the VIS region of the spectrum (380 to 780 nm, transmission coefficient Ty) was determined according to DIN ISO 13468-2:2006 (D65,10°). The transmission measurements were carried out using a Lambda 950 spectrophotometer from Perkin Elmer with a photometer sphere.

[0154] To determine a “black panel effect” a camera objective was placed on a raisable platform in a box darkened with velvet. The open side of the box was taped shut with cardboard. An opening was then cut into the cardboard so that the camera objective was visible and the mouldings could be placed in front of the opening.

[0155] Whether or not a sensor apparatus located behind the moulding is discernible in daylight was specified as the criterion for success. Settings: Exposure 1/10s, shutter F/4, ISO 400. For the mouldings according to the invention this is the case only in outline, if at all. The results are recorded in the “black panel” column. The abbreviations are ++(good), +(relatively good), 0 (in outline) and—(not discernible).

[0156] To evaluate the fitness for purpose of a camera for visible light, a Canon EOS 600D with the EFS 18-55 mm standard zoom objective was used. The settings for the objective were: Exposure 1/25s, shutter f 8.0 and ISO 400.

[0157] Measurement was performed in a measuring room with incident sunlight. The camera and the object were in shade so that only diffuse light was present in the measuring region. A Pantec LM-20 Digital Luxmeter recorded readings of about 2800 lux in front of the object and about 700 lux in front of the lens. Specified as the criterion for success here was whether a test object could still be seen with the camera through the moulding. For the mouldings according to the invention the results were good or adequate. The results are recorded in the “dark/dark” column. The abbreviations are ++(good), 0 (adequate) and—(not discernible).

[0158] The reported thicknesses of the mouldings investigated did not account for any coatings due to their low thickness.

[0159] The formulations for the employed mouldings 1 to 8 were as follows:

TABLE-US-00001 PC1 A B C D wt % wt % wt % wt % wt % moulding 3 99.98427 0.0008 0.004 0.00063 0.0103 moulding 1 99.98164 0.00093 0.0047 0.00073 0.012 moulding 2 99.9762 0.0012 0.0061 0.0009 0.0156 moulding 4 99.97433 0.0013 0.0066 0.00097 0.0168 moulding 5 99.9721 0.0014 0.0072 0.001 0.0183 moulding 6 99.9643 0.0018 0.0092 0.0013 0.0234 moulding 7 99.958 0.0021 0.0108 0.0015 0.0276 moulding 8 99.9435 0.0028 0.0146 0.002 0.0371

TABLE-US-00002 Sum of A + B + Sum of A + B + Sum of A + B + D D * 2.3 mm D * 2.5 mm wt % wt % mm wt % mm moulding 3 0.0151 0.03473 0.036179 moulding 1 0.01763 0.040549 0.042228 moulding 2 0.0229 0.05267 0.05474 moulding 4 0.0247 0.05681 0.059041 moulding 5 0.0269 0.06187 0.06417 moulding 6 0.0344 0.07912 0.08211 moulding 7 0.0405 0.09315 0.0966 moulding 8 0.0545 0.12535 0.12995

[0160] For the material PC2 the sum of violet and green dyes is 0.2 wt %. A layer thickness of 0.1 mm equates to 0.02 wt % mm, a layer thickness of 0.175 mm to 0.035 wt % mm and a layer thickness of 0.5 mm to 0.1 wt % mm.

[0161] The examples of example group 1 investigated individual coloured polycarbonate mouldings in uncoated (“1K”) form and coated with AS 4700 F (“1K-B”). The terms “LiDAR-side component” and “road-side component” specify the orientation of the mouldings investigated, i.e. whether they are facing the LiDAR sensor or facing outwards which during use of the system in a vehicle would be facing the road. The examples of example group 1 relate to one-component constructions containing no further mouldings. Thus nothing is recorded in the “road-side component” column.

[0162] In examples nos. 1 to 8 lower LiDAR signals than expected were observed on account of light scattering at the surfaces of the sample sheets, thus preventing any useful information from being obtained. The column “LiDAR signal based on air value in %” thus does not contain any measured values.

[0163] In the examples of example group 2 a two-component construction for the cover was investigated. The coloured mouldings were in each case oriented towards the LiDAR side. In examples nos. 19 to 23 the mouldings were covered with a 3.2 mm-thick layer of the transparent polycarbonate PC3 on its side facing outwards which during use of the system in a motor vehicle would be facing the road. In examples nos. 24 to 26 two identical mouldings were joined to one another, wherein both the side of the component part facing the road and the side of the component part facing the LiDAR sensor/the camera were provided with the scratch resistant coating AS 4700 F. Examples nos. 27 to 31 are a combination of a coloured moulding, a transparent 2.3 mm-thick AG PC3 layer and a scratch resistant coating with AS 4700 F both on the side of the component part facing the road and on the side of the component part facing the LiDAR sensor/the camera.

[0164] The examples of example group 3 relate to combinations of the coloured film PC2 having the specified film thicknesses and a 3.2 mm-thick transparent PC4 film without any coating and with the scratch resistant coating AS 4700 F both on the side of the component part facing the road and on the side of the component part facing the LiDAR sensor/the camera.

[0165] Further experiments were performed with coloured polycarbonates containing IR absorbers. These are summarized in example group 4. The attenuation of the LiDAR laser was too strong, as a result of which these polycarbonates were not suitable for the uses according to the invention. The employed polycarbonate formulations are reported below the table for example group 4.

[0166] In the tables which follow, “both sides” is to be understood as meaning that both the side facing outwards and the side facing the LiDAR are coated.

[0167] Example group 1 (*: comparative example):

TABLE-US-00003 LiDAR signal LiDAR-side Road-side Thickness Black Dark/ #Ty[%] T 400 T 400 T 400 based on air No. Construction component component Coating mm panel Dark (D65 10°) to 900 to 1000 to 1100 value in %  1* 1K moulding 3 none none 2.5 + ++ 29 48 55 60 —  2 1K moulding 1 none none 2.5 0 ++ 24 46 53 58 —  3 1K moulding 2 none none 2.5 0 ++ 17 41 49 55 —  4 1K moulding 4 none none 2.5 0 ++ 15 40 48 54 —  5 1K moulding 5 none none 2.5 − 0 13 39 47 53 —  6 1K moulding 6 none none 2.5 − 0 7 35 44 51 —  7 1K moulding 7 none none 2.5 − 0 5 33 43 49 —  8* 1K moulding 8 none none 2.5 − − 2 30 40 47 —  9* 1K moulding 1 none none 2.3 ++ ++ 25 46 53 58 74 10 1K moulding 2 none none 2.3 0 ++ 20 42 50 56 70 11 1K moulding 4 none none 2.3 0 ++ 20 42 50 56 71 12 1K moulding 7 none none 2.3 − 0 7 33 42 49 70 13* 1K moulding 8 none none 2.3 − − 2 28 38 45 67 14* 1K-B moulding 1 none AS 4700 F 2.3 ++ ++ 26 47 55 60 85 both sides 15 1K-B moulding 2 none AS 4700 F 2.3 0 ++ 20 43 51 57 77 both sides 16 1K-B moulding 4 none AS 4700 F 2.3 0 ++ 20 43 51 57 84 both sides 17 1K-B moulding 7 none AS 4700 F 2.3 − 0 7 34 44 51 81 both sides 18* 1K-B moulding 8 none AS 4700 F 2.3 − − 2 29 39 47 84 both sides

[0168] Example group 2 (*: comparative example):

TABLE-US-00004 LiDAR signal LiDAR-side Road-side Thickness Black Dark/ #Ty[%] T 400 T 400 T 400 based on air No. Construction component component Coating mm panel Dark (D65 10°) to 900 to 1000 to 1100 value in % 19* 1K-D moulding 1 PC3 none 2.3 + 3.2 ++ ++ 22 41 48 53 69 20 1K-D moulding 2 PC3 none 2.3 + 3.2 0 ++ 18 38 45 51 65 21 1K-D moulding 4 PC3 none 2.3 + 3.2 − ++ 17 38 45 50 65 22 1K-D moulding 7 PC3 none 2.3 + 3.2 − 0 6 30 38 44 67 23* 1K-D moulding 8 PC3 none 2.3 + 3.2 − − 2 25 34 41 68 24 1K-D moulding 1 moulding 1 AS 4700 F 2.3 + 2.3 − 0 7 32 40 46 74 both sides 25 1K-D moulding 2 moulding 2 AS 4700 F 2.3 + 2.3 − 0 5 30 38 44 65 both sides 26 1K-D moulding 4 moulding 4 AS 4700 F 2.3 + 2.3 − 0 4 29 38 44 68 both sides 27* 1K + AG-B moulding 1 PC3 AS 4700 F 2.3 + 3.2 ++ ++ 24 44 51 56 73 both sides 28 1K + AG-B moulding 2 PC3 AS 4700 F 2.3 + 3.2 0 ++ 18 40 48 54 69 both sides 29 1K + AG-B moulding 4 PC3 AS 4700 F 2.3 + 3.2 0 ++ 18 40 48 54 67 both sides 30 1K + AG-B moulding 7 PC3 AS 4700 F 2.3 + 3.2 − 0 7 32 41 47 67 both sides 31* 1K + AG-B moulding 8 PC3 AS 4700 F 2.3 + 3.2 − − 2 27 37 44 71 both sides

[0169] Example group 3 (*: comparative example):

TABLE-US-00005 LiDAR-side Road-side Black Dark/ #Ty[%] T 400 T 400 T 400 LiDAR signal based No. Construction component component Coating panel Dark (D65 10°) to 900 to 1000 to 1100 on air value in % 32* 2K-F PC2, 100 μm PC 4 AS 4700 F ++ ++ 32 61 67 70 85 both sides 33 2K-F PC2, 175 μm PC 4 AS 4700 F 0 ++ 19 53 60 64 87 both sides 34 2K-F PC2, 250 μm PC 4 AS 4700 F − ++ 9 46 54 59 86 both sides 35 2K-F PC2, 375 μm PC 4 AS 4700 F − ++ 5 41 50 56 81 both sides 36 2K-F PC2, 500 μm PC 4 AS 4700 F − 0 2 37 47 53 85 both sides 37* 2K-F PC2, 100 μm PC 4 none ++ ++ 37 60 65 69 78 38 2K-F PC2, 175 μm PC 4 none 0 ++ 18 50 57 62 78 39 2K-F PC2, 250 μm PC 4 none − ++ 9 44 52 57 77 40 2K-F PC2, 375 μm PC 4 none − ++ 5 41 49 55 77 41 2K-F PC2, 500 μm PC 4 none − 0 2 36 45 51 81

[0170] Example group 4 (*: comparative example):

TABLE-US-00006 LiDAR-side Black Dark/ #Ty[%] T 400 T 400 T 400 LiDAR signal based No. Construction component Coating panel Dark (D65 10°) to 900 to 1000 to 1100 on air value in % 42* IK PC-IR-1 none ++ ++ 26.84 39.38 44.15 47.79 42.38 43* IK PC-IR-2 none 0 ++ 22.7 41.34 46.48 50.36 44.9 45* 1K-B PC-IR-1 AS 4700 F ++ ++ 27.67 40.36 45.3 49.07 47.5 both sides 47* 1K-B PC-IR-3 AS 4700 F − − 5.44 3.01 2.6 2.31 1.52 both sides 48* 1K-B PC-IR-4 AS 4700 F 0 ++ 21.11 30.16 33.77 36.72 25.5 both sides

[0171] In the IR absorber-containing polycarbonate formulations which follow, polycarbonate constitutes the difference to 100% by weight. Reported amounts are in each case based on the total weight of the composition.

[0172] PC-IR-1: Macrolex Red EG 0.004 wt %; Macrolex Violet 3R 0.001 wt %; Heliogen Blue K6911 0.0024 wt %; Black Pearls 800 (carbon black) 0.0011 wt %.

[0173] PC-IR-2: Oracet Yellow 180 0.0004 wt %; Macrolex Red EG 0.0045 wt %; Macrolex Green 5B 0.0046 wt %; Black Pearls 800 (carbon black) 0.0009 wt %.

[0174] PC-IR-3: LaB.sub.6 (IR absorber; in acrylate matrix) 0.0135 wt %; Lumogen IR765 (IR-absorber; quaterylene structure) 0.0018 wt %; Macrolex Blue RR 0.0032 wt %; Macrolex Red EG 0.0031 wt %; Black Pearls 800 (carbon black) 0.0014 wt %.

[0175] PC-IR-4: Macrolex Red E2G 0.0015 wt %; Macrolex Violet B 0.0012 wt %; Heliogen Blue K6911 0.0010 wt %; Black Pearls 800 (carbon black) 0.0022 wt %.