LIDAR DETECTION DEVICE PROVIDED WITH A LAMINATED PROTECTIVE LAYER

Abstract

A detection device includes a Light Detection and Ranging (LiDAR) device enclosed in housing with a glass cover that has a mean transmittance at the LiDAR operating wavelength of at least 80%, to an IR-radiation in the wavelength range from 750 to 1650 nm. The glass cover is laminated and includes at least one glass sheet laminated with at least one thermoplastic interlayer. The thermoplastic interlayer has a mean transmittance at the LiDAR operating wavelength of at least 80%, to an IR-radiation in the wavelength range from 750 to 1650 nm, and has a light transmission in the visible range of less than 10% of the incident light.

Claims

1. A detection device comprising, a Light Detection and Ranging (LiDAR) device, enclosed in housing provided with a glass cover having a mean transmittance at a LiDAR operating wavelength of at least 80%, to an IR-radiation in a wavelength range from 750 to 1650 nm, wherein the glass cover is a laminated glass cover comprising at least one glass sheet laminated with at least one thermoplastic interlayer, the thermoplastic interlayer having a mean transmittance at the LiDAR operating wavelength of at least 80%, to an IR-radiation in the wavelength range from 750 to 1650 nm, and having a light transmission in a visible range, of less than 10% of incident light.

2. The detection device according to claim 1, wherein the glass cover and the at least one thermoplastic interlayer have the mean transmittance at the LiDAR operating wavelength of at least 80%, to the IR-radiation in the wavelength range from 750 to 1050 nm.

3. The detection device according to claim 1, wherein the least one thermoplastic interlayer has light transmission in the visible range of less than 5% of the incident light.

4. The detection device according to claim 1, wherein the thermoplastic interlayer has light transmission equal to 0% of the incident light.

5. The detection device according to claim 1, wherein the thermoplastic interlayer is a bulk-dyed interlayer with an IR-transparent ink.

6. The detection device according to claim 1, wherein the thermoplastic interlayer is a bulk-dyed interlayer with a black IR-transparent ink.

7. The detection device according to claim 1, wherein the glass cover is made of two glass sheets laminated with a black interlayer transparent to IR having the mean transmittance at the LiDAR operating wavelength of at least 80%, to the IR-radiation in the wavelength range from 750 to 1650 nm, and having light transmission in the visible range of less than 10% of the incident light.

8. The detection device according to claim 1, wherein the glass cover is selected from a group consisting of soda lime glass, borosilicate glass, aluminosilicate glass, glass-ceramic and quartz glass.

9. The detection device according to claim 1, wherein the thermoplastic interlayer is a polymer sheet selected from a group consisting of polyvinyl butyral, polyurethane, polycarbonate, polyester, copolymers, ethylene-vinyl acetate, cyclo-olefin polymer, silicone, and polyolefin.

10. The detection device according to claim 1, wherein the thermoplastic interlayer is a printed interlayer with an IR-transparent ink or dye.

11. The detection device according to claim 1, wherein the thermoplastic interlayer is a polyvinyl butyral interlayer batch-dyed or printed with a black IR-transparent ink.

12. The detection device according to claim 1, wherein the laminated glass cover is bent.

13. The detection device according to claim 1, wherein the glass cover is integrated on/in an exterior element of a vehicle selected from a group consisting of a fender, a bumper, a grill, a wing mirror cover, a side door, a pillar (A, B, C, D), a door, a roof of a vehicle, and a trim element.

14. The detection device according to claim 1, wherein the glass cover comprises a transparent part of an automotive vehicle, selected from a group consisting of a windscreen, a rear window, a lateral window, a headlight and a tail light cover.

15. An automotive vehicle comprising the detection device according to claim 1, wherein the automotive vehicle is a self-driving vehicle.

16. The detection device according to claim 1, wherein the thermoplastic interlayer has the mean transmittance at the LiDAR operating wavelength of at least 90% to the IR-radiation in the wavelength range from 750 to 1650 nm.

17. The detection device according to claim 2, wherein the thermoplastic interlayer has the mean transmittance at the LiDAR operating wavelength of at least 80% to the IR-radiation in the wavelength range from 750 to 950 nm.

18. The detection device according to claim 3, wherein the thermoplastic interlayer has light transmission in the visible range of less than 2% of the incident light.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0059] For a fuller understanding of the nature of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings in which:

[0060] FIG. 1: shows an exploded view of a detection device according to the present invention.

[0061] FIG. 2: shows an automotive vehicle with various locations where a detection device according to the present invention can be located.

DETAILED DESCRIPTION OF THE INVENTION

[0062] As illustrated in FIG. 1, the present invention concerns a LiDAR device comprising a solid-state LiDAR device (21) enclosed in a housing (11) provided with a glass cover (12) made of a first glass sheet (13), a thermoplastic interlayer (31) and a second glass sheet (14). According to the present invention , the first (13) and the second (14) glass sheet having a mean transmittance at the LiDAR operating wavelength of at least 80%, preferably of at least 90% to an IR-radiation in the wavelength range from 750 to 1650 nm, preferably in the range of 750 to 1050 nm, more preferably in the range of 750 to 950 nm. The thermoplastic interlayer has having a mean transmittance at the LiDAR operating wavelength of at least 80%, preferably of at least 90% to an IR-radiation in the wavelength range from 750 to 1650 nm, preferably in the range of 750 to 1050 nm, more preferably in the range of 750 to 950 nm, and having a light transmission in the visible range (380-780 nm), less than 10% of the incident light and preferably less than 5% of the incident light and more preferably less than 2% of the incident light and very more preferably equal to 0% of the incident light. Such thermoplastic interlayer is a PVB interlayer dyed in the bulk with a black IR-transparent ink such as provided by Teikoku, Toray or any known IR-transparent ink having a light transmission in the visible range (380-780 nm), less than 10% of the incident light and preferably less than 5% of the incident light and more preferably less than 2% of the incident light. The LiDAR must be enclosed in a housing to protect it from external aggressions, such as dirt and impacts from gravel or hail. The present invention proposes a solution for prolonging the service life of a LiDAR system, while ensuring the efficiency of the Lidar and giving a good aesthetic. The glass cover is then more resistant and the weak light transmission of the thermoplastic interlayer while being transparent to IR- radiation allow to provide a very efficient glass cover to be fixed to the housing enclosing the LiDAR with required optical properties.

[0063] As discussed above, solid-state LiDAR comprise a phase array of optical emitters (lasers) which create a beam of optical waves that can be electronically steered to point in different directions without moving the optical emitters. Each optical emitter is set with a phase relationship such that the optical waves from the separate emitters add together to increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions. In a phased array, a beam of optical waves can be steered to a different direction by controlling the phase shift between emitters.

[0064] To protect the solid state LiDAR from external aggressions, it is enclosed in a housing comprising a glass cover to allow the passage of emitted radiations as well as of returned radiation bounced back on an obstacle.

Glass cover (12)

[0065] The emitted radiations must traverse the glass cover (12) of the housing (11) until they hit an obstacle and part of the radiations are reflected back to the detection device, where they must traverse the glass cover (12) again before reaching an optical sensor. The glass cover (12) to be traversed by the incident beam and a return beam reflected off an obstacle must have a high transmittance to infrared light, commonly used in LiDARs mounted on automotive vehicles(40).

[0066] It is essential for the good functioning of the LiDAR detection device (1) that the glass cover (12) has, on the one hand, a high transmittance, to the wavelengths emitted by the LiDAR, which are generally comprised within the IR-range, preferably between 750 to 1650 nm. It is important for the service life of the LiDAR detection device that these values be maintained during use of a vehicle, exposing the glass cover (12) to external aggressions including rain, frost, and impacts from hail and gravels.

[0067] For reducing absorption of IR-radiations, the glass sheet should be as thin as possible. It is preferred that the glass sheet have a thickness of not more than 2 mm, preferably not more than 1 mm. The glass sheet preferably has a weak while keeping its robustness.

[0068] The glass sheet can be a soda lime glass sheet. An example of soda lime glass composition comprises the following components:

TABLE-US-00001 SiO.sub.2 55-85%  Al.sub.2O.sub.3 0-30% B.sub.2O.sub.3 0-20% Na.sub.2O 0-25% CaO 0-20% MgO 0-15% K.sub.2O 0-20% BaO 0-20% Cr.sub.2O.sub.3 0.0001-0.06%.     Co  0-1% Total iron (expressed as Fe.sub.2O.sub.3) 0.002-1%  

[0069] Such glass sheet has a very high transmittance to IR-radiations used by LiDARs detection devices in automotive vehicles. The glass cover (12) can also be made of glass. Preferably, the glass cover (12) is made of glass and has a composition within the ranges defined supra for the glass sheet.

[0070] According to one embodiment of the present invention, the glass cover can be a coated layer applied onto the outer surface of the glass cover (12) by any known technique such as, dip-coating, spraying, or sputtering. The coating must be removable with a solvent, other than water (because of rain), by a heat treatment which does not affect negatively the glass cover the coating is adhered to, or by mechanically scraping the coating.

[0071] The glass cover (12) can have a three-dimensional (3D-) geometry.

[0072] Because rain and frost can temporarily disrupt the optical properties of the assembly of a glass cover (12), the latter can comprise a hydrophobic outer surface, exposed to atmosphere when covering the glass cover (12). The hydrophobicity can be obtained either by the choice of a polymer sheet or coating having a low surface energy, or by applying a hydrophobic layer to the glass cover. A surface is considered as being hydrophobic when a water droplet laid on the surface forms a static water contact angle greater than 90°.

[0073] The optical properties of the thermoplastic interlayer according to the present invention does not hinder the good functioning of the LiDAR detection device based on transmission of light beams through a glass cover. The main objective of the laminated glass cover (12), however, is the protection of the optical sensor of the LiDAR. This can be achieved with the mechanical properties discussed below.

[0074] A detection device according to the present invention is particularly suitable for use in automotive vehicles, ships, airplanes, and the like. Preferably, a detection device according to the present invention is mounted on an automotive vehicle, more preferably on a self-driving automotive vehicle. Automotive vehicles include cars, vans, lorries, motor bikes, buses, trams, trains, and the like.

[0075] FIG. 2 shows a typical car and also shows examples of localizations of detection devices by the enclosed numeral (1). Detection devices can be mounted on/in body elements (41) including fenders, bumpers, grills, wing mirror covers, bonnet, boot, side doors, a pillar (A, B, C, D), or back doors. Detection devices can also be mounted behind transparent body elements (42) including front windscreen, rear window, lateral windows, headlight or tail light covers, and the like. It is understood that when the LiDAR comprising the laminated glass cover according to the invention, is a part of a windscreen or more generally a window, the LiDAR is placed in a zone outside the field of view. The LiDAR should not be placed in a zone wherein a light transmission in the visible range more than 10% of the incident light is needed.

TABLE-US-00002 REF# Feature 1 Detection device 11 Housing 12 Glass cover 21 Solid state LiDAR 31 thermoplastic layer 40 Automotive vehicle 41 Non-transparent body element 42 Transparent body element