FIELD OF THE INVENTION

[0001] The present invention relates to the field of near-infrared sensor covers, more specifically to glass covers with a decorative element.

BACKGROUND OF THE INVENTION

[0002] Trend nowadays is to equip vehicles with increasing number of sensors. Optical cameras and radar are the most used sensors. While these sensors are becoming more and more important, especially for partly- of fully-automated driving, the tendency is to hide such sensors for aesthetical purpose.

[0003] EP3300169, US6184842, WO2019130033 describe covers which are compatible for a radar system. These covers show the emblem of the vehicle manufacturer. The emblem is made so that it does not impair the functioning of the radar placed behind, while allowing increased visibility of the logo through metallic coating.

[0004] W02020208105 describes a radar cover showing an emblem which is also compatible with a camera. The emblem is transparent for the radar, while the camera perceives signals through opening within the emblem.

[0005] Lidar is another type of sensor which is increasingly used in the automotive field. Such lidar is usually placed on the bodywork of the vehicle, meaning such lidar pops out from the vehicle as a mushroom. Such incorporation is not seen as aesthetical for vehicle manufacturer, and the tendency is to incorporate such lidar within the bodywork of vehicles, such as behind a window (as described in WO201 8178284) or behind an external trim element (as described in WO2018178286) of the vehicle.

[0006] However adding an emblem in front of such lidar based on the approaches used for the radar does not result into an efficient product. As a lidar is working at very different wavelength than a radar, solutions available for the radar does not function for the lidar.

[0007] There is therefore a need for a cover which would be compatible with a lidar and could further show the emblem of the vehicle manufacturer. i SUMMARY OF THE INVENTION

[0008] The present invention concerns a glass cover for a near-infrared sensor. The glass cover comprises at least one glass sheet having an internal face facing the nearinfrared sensor and an external face opposite to the internal face. The glass sheet has an absorption coefficient lower than 15m’ ¹ in the operating wavelength range of the near-infrared sensor. The glass cover further comprises a decorative element which is transparent in the operating wavelength range of the near-infrared sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention will now be described further, byway of examples, with reference to the accompanying drawings, wherein like reference numerals refer to like elements in the various figures. These examples are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples.

[0010] FIG. 1 illustrates a cover made of a monolithic glass according to the present invention.

[0011] FIG. 2a illustrates a laminated cover according to the present invention. FIG. 2b shows the same laminated cover but with a coloured internal glass.

[0012] FIG. 3a illustrates an alternative laminated cover according to the present invention. FIG. 3b shows the same laminated cover but with a coloured internal glass.

[0013] FIG. 4a illustrates another alternative laminated cover according to the present invention. FIG. 4b shows the same laminated cover but with a coloured internal glass.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0014] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0015] While some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0016] The present invention proposes a cover for a near-infrared sensor. A nearinfrared sensor is a sensor whose operating wavelength range is situated in the nearinfrared wavelength range, meaning between 780nm and 1650nm. It encompasses lidar and near-infrared sensors. Lidar is an acronym for “light detection and ranging”. It is sometimes called “laser scanning” or “3D scanning”. The technology uses laser beams to create a 3D-representation of the surveyed environment. Operating wavelength of lidar compatible with the present invention is comprised between 780nm and 1650nm (usually referred to as near-infrared). More specifically, known operating wavelengths of currently produced lidars compatible with the present invention are 850nm, 905nm, 940nm, 1064nm, 1310nm, 1350nm, 1550nm, 1650nm. An acceptable variance of 25nm around the nominal value of the wavelength may be considered, such that, for example, a wavelength range of 1525nm to 1575nm may be accepted around the nominal value of 1550nm.

[0017] The cover comprises at least one glass sheet, with an internal face facing the near-infrared sensor and an external face opposite to the internal face. The glass sheet has a composition that is not particularly limited. The glass sheet may be a soda- lime-silicate glass, an alumino-silicate glass, an alkali-free glass, a boro-silicate glass, ... Preferably, the glass sheet of the invention is made of a soda-lime glass or an alumino-silicate glass. The glass sheet according to the invention may be a glass sheet obtained by a floating process, a drawing process, a rolling process or any other process known to manufacture a glass sheet starting from a molten glass composition. According to a preferred embodiment according to the invention, the glass sheet is a float glass sheet. The term “float glass sheet” is understood to mean a glass sheet formed by the float glass process, which consists in pouring the molten glass onto a bath of molten tin, under reducing conditions. The glass sheet preferably has a thickness comprised between 0.5mm and 6mm, more preferably between 1 mm and 4mm. Usual thickness for such glass sheet is 1.6mm, 2.1 mm, 3.1 mm or 4mm.

[0018] The glass sheet has an absorption coefficient lower than 15m’ ¹ in the operating wavelength range of the near-infrared sensor, preferably less than 10m’ ¹ , even more preferably less than 5m’ ¹ .

[0019] To quantify the low absorption of the glass sheet in the near-infrared range, in the present description, the absorption coefficient is used in the wavelength range from 780nm to 1650nm. The absorption coefficient is defined by the ratio between the absorbance and the optical path length traversed by electromagnetic radiation in a given environment. It is expressed in rrr ¹ . It is therefore independent of the thickness of the material but it is function of the wavelength of the absorbed radiation and the chemical nature of the material.

[0020] In the case of glass, the absorption coefficient (p) at a chosen wavelength X can be calculated from a measurement in transmission (T) as well as the refractive index n of the material (thick = thickness), the values of n, p and T being a function of the chosen wavelength X: with p = (n-1 ) ² /(n+1 ) ² .

[0021] According to the present invention, the glass sheet having an absorption coefficient at the operating wavelength of near-infrared sensor of less than 15m’ ¹ , preferably less than 10m’ ¹ , even more preferably less than 5m’ ¹ , may be a soda-lime- silica glass, alumino-silicate, boro-silicate, ...

[0022] Preferably, a glass composition compatible with the present invention comprises a total content expressed in weight percentages of glass:

SiO ₂ 55 - 85%

AI2O3 0 - 30%

B2O3 0 - 20%

Na ₂ O 0 - 25%

CaO 0 - 20%

MgO 0 - 15%

K ₂ O 0 - 20%

BaO 0 - 20%.

[0023] More preferably, a glass composition compatible with the present invention comprises in a content expressed as total weight of glass percentages: SiO ₂ 55 - 78%

AI2O3 0 - 18%

B2O3 0 - 18%

Na ₂ O 0 - 20%

CaO 0 - 15%

MgO 0 - 10%

K ₂ O 0 - 10%

BaO 0 - 5%

[0024] More preferably, for reasons of lower production costs, the glass compatible with the present invention is made of soda-lime glass. A glass composition compatible with the present invention comprises a content expressed as the total weight of glass percentages:

SiO ₂ 60 - 75%

AI2O3 0 - 6%

B2O3 0 - 4%

CaO 0 - 15%

MgO 0 - 10%

Na ₂ O 5 - 20%

K ₂ O 0 - 10%

BaO 0 - 5%.

[0025] In addition to its basic composition, the glass may include other components, nature and adapted according to quantity of the desired effect. A solution to obtain a very transparent glass in the near-infrared, with weak or no impact on its aesthetic or its color, is to combine in the glass composition a low iron quantity and optionally chromium in a range of specific contents. Thus, the glass preferably has a composition which comprises a content expressed as the total weight of glass percentages:

Fe total (expressed asFe2O3) 0,002 - 0,06%

Cr ₂ O ₃ 0 - 0,06 %. [0026] Such glass compositions combining low levels of iron and chromium showed particularly good performance in terms of near-infrared reflection and show a high transparency in the visible and a little marked tint, near a glass called "extra-clear These compositions are described in international applications W02014128016A1 , WO2014180679A1 , W02015011040A1 , WO2015011041 A1 , W02015011042A1 , WO201 5011043A1 and WO2015011044A1 .

[0027] The glass cover comprises a decorative element which is transparent in the operating wavelength range of the near-infrared sensor. Such decorative element can be a logo, an emblem of a vehicle manufacturer, a pattern, ...

[0028] According to an embodiment, the decorative element is printed on the internal face or the external face of the at least one glass sheet with an ink and/or an enamel which is transparent in the operating wavelength range of the near-infrared sensor.

[0029] According to an embodiment, the glass cover comprises an exterior glass sheet having an internal face facing the near-infrared sensor and an external face opposite to the internal face. The exterior glass sheet has an absorption coefficient lower than 15m’ ¹ in the operating wavelength range of the near-infrared sensor. The glass cover further comprises an interior glass sheet having an internal face facing the nearinfrared sensor and an external face opposite to the internal face. The interior glass sheet has an absorption coefficient lower than 15m’ ¹ in the operating wavelength range of the near-infrared sensor. The exterior glass sheet and the interior glass sheet are laminated with at least one laminating interlayer. The at least one laminating interlayer is transparent in the operating wavelength range of the near-infrared sensor. The decorative element is printed on the internal face or the external face of the exterior glass sheet and/or on the internal face or the external face of the interior glass sheet and/or on the at least one laminating interlayer with an ink and/or an enamel which is transparent in the operating wavelength range of the near-infrared sensor.

[0030] According to an alternative embodiment, the decorative element is coated on the internal face or the external face of the exterior glass sheet and/or on the internal face or the external face of the interior glass sheet with a coating which is transparent in the operating wavelength range of the near-infrared sensor.

[0031] According to an alternative embodiment, the glass cover further comprises at least one diecut interlayer between the exterior glass sheet and the at least one laminating interlayer. The at least one diecut interlayer is transparent in the operating wavelength range of the near-infrared sensor. The at least one diecut interlayer has a diecut forming the decorative element. In a preferred embodiment, the at least one laminating interlayer further comprises an ink and/or an enamel which is transparent in the operating wavelength range of the near-infrared sensor corresponding to a zone of the diecut. In another preferred embodiment, the decorative element is formed by the overlapping of several laminating interlayers.

[0032] When the glass cover comprises an exterior glass sheet and an interior glass sheet, the interior glass sheet may be further colored in the visible wavelength range. Such coloration may be done in the bulk, meaning the glass material itself is colored. Such coloration may also be done by a print layer or a coating on either internal or external faces. Such coloration may be done to render the interior glass sheet opaque to visible wavelength range in order to hide the near-infrared sensor placed behind. For example, the interior glass sheet may have a transmission in the visible wavelength range of less than 2%. The visible wavelength range is defined as from 380nm to 780nm. In the present description, to quantify the luminous transmittance, one considers the total light transmission with illuminant A as defined in CIE15 with CIE1931 standard colorimetric observer 2°. The luminous transmittance represents the percentage of light flux emitted between wavelengths 380nm and 780nm which is transmitted through the cover. The interior glass sheet is understood to have a luminous transmittance of less than 2%, preferably less than 1 %. It allows to hide the near-infrared sensor placed behind. The interior glass sheet can be colored in the bulk, meaning that the material of the interior glass sheet itself is colored in the visible wavelength range (while still being transparent at the operating wavelength range of the near-infrared sensor). The interior glass sheet could also be printed (with an ink or an enamel) or coated (for example through plasma vapor deposition process or any other process known by the skilled in the art) in order to render it opaque in the visible wavelength range.

[0033] In a preferred embodiment, the glass cover further comprises an area free of the decorative element. Such area may be used in order for an optical system such as a camera to be placed behind the glass cover, in addition to the near-infrared sensor, while not impairing the field of view of the camera with the decorative element.

[0034] According to a preferred embodiment, the glass cover further comprises a frame surrounding the glass cover. Such frame is at least partially made of a plastic material and/or a metallic material.

[0035] According to a preferred embodiment, the glass cover is bent.

[0036] According to a preferred embodiment, the glass cover is a part of a windshield, backlite or sidelite of a vehicle, or part of an exterior trim element. An exterior trim element includes bumper, window/door seal, pillar, wheel well, wheel arch, fender, headlight, mirror body and roof cover. Such exterior trim element can also be deployable, meaning it can pop out from the vehicle only when needed. Vehicle manufacturers use these exterior trim elements to add aesthetics, increase function, and add flexibility to the vehicle design.

[0037] According to a preferred embodiment, the glass cover can further comprise an antireflection layer in the operating wavelength range of the near-infrared sensor. Such antireflection layer allows to decrease reflection, and therefore to increase the signal sent and/or received to/from the near-infrared sensor. As an example, an antireflection layer may be a layer based on porous silica having a low refractive index or it may be composed of several layers (stack), in particular a stack of layers of dielectric material alternating layers having low and high refractive indexes and terminating in a layer having a low refractive index. Such layer may be provided on any of the faces of the at least one glass sheet of the glass cover. A textured glass sheet may be also used. Etching or coating techniques may as well be used in order to avoid reflection. Preferably, the reflection of the treated surface would decrease from at least 1 % and preferably from at least 2% if both surfaces are coated, within the concerned wavelength range. The antireflection layer may be a layer based on refractive index gradient layer deposited for example by ion implantation technique.

[0038] According to another advantageous embodiment of the invention, the glass cover may be coupled with a heating system that allows the glass cover to quickly defrost or defog when the external operating conditions are unfavorable. Such heating system can be composed of a network of conductive wires, conductive patch or alternatively a silverprint network directly applied on the glass surface where an adequate power supply can be applied. Optionally, the system can also comprise a temperature sensor for dynamically triggering the heating function in case of need.

[0039] According to another advantageous embodiment of the invention, the glass cover may be coated with a hydrophobic layer that prevents water droplets to aggregate onto the glass cover. Such coating allows to ensure proper sensor operation in case of rain (snow, frost) and/or in case of fog. Such water repellant coating can be, for example, composed of thin molecular layers of fluoropolymers that reduces the surface energy and provides self-cleanability, anti-stain properties and improved moisture resistance among other effects.

[0040] Other suitable advantageous functionalities can be added to the glass sheet of the glass cover of the invention, in particular to provide supporting functions to further enhance the good operation of the near-infrared sensor. Those supporting functions can be for example: the coupling with integrated detection functions for breakage, dirt, stain, min, ... or additional protection layers for preventing scratches, glare, stain, dirt, paint, ... Dedicated filters could also be integrated for polarization, phase or spectral discrimination.

[0041] Referring to Fig.1 , a glass cover (1 ) is placed in front of a near-infrared sensor (2). The glass cover (1 ) comprises a glass sheet (10) having an absorption coefficient lower than 15m’ ¹ in the operating wavelength range of the near-infrared sensor (2). A decorative element (3) is placed on the internal face of the glass sheet (10), meaning the face facing the near-infrared sensor (2). However, such decorative element (3) could be placed on the external face of the glass sheet (10), meaning on the opposite face to the internal face. The decorative element is transparent in the operating wavelength range of the near-infrared sensor (2). Such decorative element (3) is printed on the glass sheet (10) with an ink and/or an enamel which is transparent in the operating wavelength range of the near-infrared sensor (2). Such decorative element (3) can also be coated on the glass sheet (10) with a coating which is transparent in the operating wavelength range of the near-infrared sensor (2).

[0042] Referring to Fig.2a, a glass cover (1 ) is placed in front of a near-infrared sensor (2). The glass cover (1 ) comprises an external glass sheet (11 ) and an internal glass sheet (14). Both glass sheets (11 , 14) have an absorption coefficient lower than 15rrr ¹ in the operating wavelength range of the near-infrared sensor (2). Both glass sheets (11 , 14) are laminated by a laminating interlayer (13). Such laminating interlayer is transparent in the operating wavelength range of the near-infrared sensor (2). A decorative element (3) is printed on the internal face of the external glass sheet (11 ) with an ink and/or an enamel which is transparent in the operating wavelength range of the near-infrared sensor (2). However, this decorative element (3) could also be printed on the external face of the external glass sheet (11 ), and/or on the internal face or the external face of the interior glass sheet (14) and/or on the laminating interlayer (13).

[0043] Instead of (or in combination with) the decorative element (3) being printed, it could also be coated on the internal face or the external face of the exterior glass sheet (11 ) and/or on the internal face or the external face of the interior glass sheet (14) with a coating which is transparent in the operating wavelength range of the near-infrared sensor (2).

[0044] Fig.2b shows the same embodiment as Fig.2a, except that the internal glass sheet (14) is opaque in the visible wavelength range. Such configuration allows to hide the near-infrared sensor (2).

[0045] Referring to Fig.3a, a glass cover (1 ) is placed in front of a near-infrared sensor (2). The glass cover (1 ) comprises an external glass sheet (11 ) and an internal glass sheet (14). Both glass sheets (11 , 14) have an absorption coefficient lower than 15rrr ¹ in the operating wavelength range of the near-infrared sensor (2). Both glass sheets (11 , 14) are laminated by a laminating interlayer (13). Such laminating interlayer is transparent in the operating wavelength range of the near-infrared sensor (2). A further diecut interlayer (12) is placed between the exterior glass sheet (11 ) and the laminating interlayer (13). This diecut interlayer (12) is transparent in the operating wavelength range of the near-infrared sensor (2). This diecut interlayer (12) shows a decorative element (3) in the form of a diecut. The diecut lets therefore see the laminating interlayer (13), seen from the outside (from the exterior glass sheet (11 )). The laminating interlayer (13) can be chosen colored in the visible wavelength range in order to show the decorative element (3) in a specific colour.

[0046] Instead of a single laminating interlayer (13), several laminating interlayers can be used, for example to create specific visual effects in the visible wavelength range.

[0047] Fig.3b shows the same embodiment as Fig.3a, except that the internal glass sheet (14) is opaque in the visible wavelength range.

[0048] Referring to Fig.4a, a glass cover (1 ) is placed in front of a near-infrared sensor (2). The glass cover (1 ) comprises an external glass sheet (11 ) and an internal glass sheet (14). Both glass sheets (11 , 14) have an absorption coefficient lower than 15rrr ¹ in the operating wavelength range of the near-infrared sensor (2). Both glass sheets (11 , 14) are laminated by a laminating interlayer (13). Such laminating interlayer is transparent in the operating wavelength range of the near-infrared sensor (2). A further diecut interlayer (12) is placed between the exterior glass sheet (11 ) and the laminating interlayer (13). This diecut interlayer (12) is transparent in the operating wavelength range of the near-infrared sensor (2). This diecut interlayer (12) shows a decorative element (3) in the form of a diecut. The diecut lets therefore see the laminating interlayer (13), seen from the outside (from the exterior glass sheet (11 )). The laminating interlayer (13) can be chosen colored in the visible wavelength range in order to show the decorative element (3) in a specific colour. The laminating interlayer (13) further comprises an ink and/or an enamel which is transparent in the operating wavelength range of the near-infrared sensor (2) corresponding to a zone of the diecut forming the decorative element (3). Such configuration allows for example for some part of the decorative element (3) being seen in another colour.

[0049] Fig.4b shows the same embodiment as Fig.4a, except that the internal glass sheet (14) is opaque in the visible wavelength range.

[0050] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. The invention is not limited to the disclosed embodiments.