The present invention relates to a component having a coated part comprising a coloring coating, providing a color effect to the front surface of the coated part, preferably providing metallic appearance, and electromagnetic spectrum-adjusting means for enabling the transmission of a light exhibiting a predetermined electromagnetic spectrum as described in the independent claim 1. The component can be radar-transparent or non-radar transparent. Preferred embodiments of the present invention are described in the dependent claims.

Further, the present invention relates also to a coating provided on a transparent or semitransparent plastic component that is selected in such a way that when it is backlit by a light source having a specific electromagnetic spectrum, the coating acts like an optical filter and transmits the light so that the visible light seen through the coating has a similar electromagnetic spectrum as the source of light without the coating, wherein when it is not backlit by a light source, the coating transmits and reflects the ambient light in such a way that it does not look completely transparent to visible light; wherein the coating is preferably transparent to electromagnetic waves, in particular radar waves (i.e. radar- transparent), a capacitive element, a part of a proximity sensor or decorative element.

State of the art

It is known that specific semiconductor coatings can be applied on plastic parts to act as proximity sensors but have a metallic shine as described in patent US10205035B2. These coatings are used for example as touch panels, decorative elements where the capacitive function is needed. Moreover, semiconductor coatings are also known to give a metallic look to plastic components but are transparent to radar as it is described in patent US9476116B2. The plastic component of a vehicle, such as a bumper, grille or a radome, can have a desired metallic look but still transmit the signal coming from a radar sensor placed behind the plastic component. The semiconductor coatings for these applications have additionally a base coating, also called primer, to smoothen the base surface of the component and improve the adhesion of the semiconductor coating and/or a top layer of lacquer in order or to protect the semiconductor coating from the environment. These type of coatings are used in the automotive industry for external components such as bumpers, grilles, radome where sensor are placed and the radar transparency is required, or where the components are simply backlit for decorative purpose. Such coatings are provided on internal components, such as touch panels, control boards which act as capacity sensor (proximity sensors) for controlling electronic circuits instead of using physical buttons. These coatings can also be used as pure decorative elements due to their high transmission of light so that they can have a metallic look during the day and can be backlit during the night.

As described before, a transparent or semi-transparent plastic component can be coated by a semiconductor material and backlit by a source of light placed behind the component for decorative purpose. However, due to the high transmission of the semiconductor with respect to the visible light, the color of the source of light is changed when it is transmitted through the coating. The shift of spectrum can vary depending on the source of light used and the material of the coating but the effect is stronger when the coating consists of several layers such as for example comprising a semiconductor layer and a top lacquer layer.

This shift in color seen through the coating could be compensated by adapting the spectrum of the source of light for each different coating system. This solution is nevertheless not acceptable as it would mean to design specific source of lights for each type of coatings and their respective application, which is economically not satisfying and not a solution desired by the manufacturer.

Another problem when providing a transparent or semi-transparent plastic component with a semiconductor coating is that the coating might have a metallic look as seen from the outside, but depending on the different exposition to the ambient light, the elements which are behind the coated transparent or semi-transparent plastic component are visible. This is not what is expected by a metallic decorative coating.

Objective of the invention

The main objective of the present invention is to provide a component, in particular a glass or plastic component, having a colored surface and allowing that a light is let through the component but resulting in a light having a predetermined electromagnetic spectrum. The component can be non-radar transparent or radar-transparent.

A further objective of the present invention is to provide a coating on a transparent or semi-transparent glass or plastic component that is selected in such a way that when it is backlit by a light source having a specific electromagnetic spectrum, the coating acts like an optical filter and transmits the light so that the visible light seen through the coating has a similar or the same electromagnetic spectrum as the source of light without the coating and the plastic component. The provided coating are transparent to electromagnetic waves, in particular radar waves, can be a capacitive element, part of a proximity sensor or a decorative element.

One more further objective of the present invention is to provide a coating on a transparent or semi-transparent component, preferably a glass or plastic component that, when it is not backlit by a light source, the coating transmits and reflects the ambient light in such a way that it does not look completely transparent to the visible light.

In the context of the present invention the term “radar-transparent” or “transparent to electromagnetic waves” is used for referring to a material that exhibits a low damping of less than 3 dB.

In the context of the present invention the term “non-radar-transparent” or “not transparent to electromagnetic waves” is used for referring to a material that exhibits a damping of 3 dB or higher.

In the context of the present invention the term “transparent material” is used for referring to a material that has practically no absorption of light. The main cause for reduction of transmission in a given environment is the refractive index change at the interfaces.

In the context of the present invention the term “semi-transparent material” is used for referring to a material that has partial absorption of light in all or some parts of the visible spectrum. It might have full absorption in some parts of the visible spectrum but not in all.

In the context of the present invention the term “metallic appearance” is used for referring to following cases: • a surface having a brightness varying with the incidence angle of the ambient light impinging on the surface, and/or

• a surface having a mean value of specular reflection of the visible spectrum of at least 20%, and/or

• a surface having a grey reflection with CIE L*ab in the range of 40 to 99 with only small coloring of the reflected white light as given in CIE L*ab -5 < a* < 5; and/or -10 < b* < 10.

Description of the present invention

The objective of the present invention is attained by providing a component comprising a light source emitting a first visible spectrum of electromagnetic waves with a first set of CIE parameters LSi=(xi;yi), said component further comprising at least a coated part, with a substrate made of a transparent or semi-transparent material, said coated part having a front surface and a back surface, where the back surface is closer to the light source than the front surface, and where a coating system is applied to the substrate on a front surface or on a back surface of the substrate, where the back surface of the substrate is closer to the light source than the front surface of the substrate, wherein the coated part comprises coloring means, that are set up to transmit light and to provide a color effect, so that when the light source is switched off and the front surface of the coated part is exposed to ambient light, the color effect is perceived by a human eye 100 and any elements located in front of the back side of the coated part are invisible to said human eye looking at the coated part from a place in front of the front side of the coated part 1 , wherein: the coated part comprises electromagnetic spectrum-adjusting means, so that when the light source is switched on, an adjusted electromagnetic spectrum that is a second visible spectrum of electromagnetic waves with a second set of CIE parameters LS2=(x2;y2) of light is transmitted through the coated part which differs from a non-adjusted set of CIE parameters LS2na=(x2n _a ;y2na) of the visible spectrum of electromagnetic waves that would be transmitted through the coated part, if no electromagnetic spectrum-adjusting means were comprised in the coated part, the electromagnetic spectrum-adjusting means being set up to lead to | LS3 - LS2I < |LSs - LS2na|, where LS3 represents a desired third set of CIE parameters LS3=(x3;y3), thereby said electromagnetic spectrum-adjusting means bringing the set of CIE parameters LS2 of the transmitted light closer to the desired set of parameters LS3.

The coloring means can be applied for example as: a) one or more coloring elements, for example one or more coloring layers or one or more coloring components or a combination thereof, or b) one or more coloring layers, forming for example a coloring coating, or c) one or more coloring layers, forming for example a coloring coating comprised in a coating system.

A part of the coloring means (for example a coloring layer and/or a coloring component) can be comprised in the electromagnetic spectrum-adjusting means.

The electromagnetic spectrum-adjusting means according to the present invention are placed between the light source and the coloring means.

In the case that a part of the coloring means is comprised in the electromagnetic spectrum-adjusting means then the electromagnetic spectrum-adjusting are placed between the light source and the part of the coloring means that is more distant from the light source.

The coloring means according to the present invention are designed for providing the necessary reduction of transmission for achievement of the hiding effect when the light source is switched off. It means the coloring means exhibit a wavelength selective reduction of transmission.

Figures 1 to 4 illustrate preferred embodiments of the present invention.

Hence the objective of the present invention is further attained by providing a component, as schematically shown in Figures 1 to 4, in these inventive embodiments the component comprising a light source 2 emitting a first visible spectrum of electromagnetic waves with a first set of CIE parameters LSi=(xi ;yi), said component further comprising at least a coated part 1 , with a substrate 10 made of a transparent or semi-transparent material, said coated part 1 having a front surface (1 FS) and a back surface 1 BS, where the back surface (1 BS) is closer to the light source 2 than the front surface 1 FS, and where a coating system 20 is applied to the substrate 10 on a front surface 1 OFS or on a back surface 1 OBS of the substrate 10, where the back surface 1 0BS of the substrate 10 is closer to the light source 2 than the front surface 1 0FS of the substrate 10, wherein the coating system 20 comprising at least one coloring coating 22, where the at least one coloring coating 22 is used as coloring means or is one ore more elements of the coloring means comprised in the component, the at least one coloring coating 22 alone or in combination with other elements of the coloring means being set up to transmit light and to provide a color effect, so that when the light source 2 is switched off and the front surface 1 FS of the coated part 1 is exposed to ambient light, the color effect is perceived by a human eye 100 and any elements located in front of the back side 1 BS of the coated part 1 are invisible to said human eye 100 looking at the coated part 1 from a place in front of the front side 1 FS of the coated part 1 , wherein: the coated part 1 comprises electromagnetic spectrum-adjusting means placed between the light source 2 and the coloring coating 22, so that when the light source 2 is switched on, an adjusted electromagnetic spectrum that is a second visible spectrum of electromagnetic waves with a second set of CIE parameters LS2=(x2;y2) of light is transmitted through the coated part 1 which differs from a non-adjusted set of CIE parameters LS2na=(x2n _a ;y2na) of the visible spectrum of electromagnetic waves that would be transmitted through the coated part 1 , if no electromagnetic spectrum-adjusting means were comprised in the coated part 1 , the electromagnetic spectrum-adjusting means being set up to lead to | LSs - LS2I < | LS3 - LS2na|, where LS3 represents a desired third set of CIE parameters LS3=(x3;y3), thereby said electromagnetic spectrum-adjusting means bringing the set of CIE parameters LS2 of the transmitted light closer to the desired set of parameters LS3.

The component according to the present invention, preferably has an adjusted second set of CIE parameters LS2=(x2;y2) that differs from the desired third set of CIE parameters LS3=(x3;ys) in a delta xy that is lower than or equal to 0.1 , i.e. | LS3 - LS2I = delta xy < 0.1 , where delta xy = sqrt((x3-X2) ² +(ys-y2) ² ), and where sqrt is the abbreviation of the mathematic operation square root. According to the present invention LSi can correspond to the electromagnetic spectrum of white light, or to an electromagnetic spectrum different from the electromagnetic spectrum of white light.

According to a preferred embodiment of the present invention the desired electromagnetic spectrum LS3 can be equal to LS1, i.e. LS3 = LS1.

According to a further preferred embodiment of the present invention the desired electromagnetic spectrum LS3 can be different from LS1, i.e. LS3 + LS1.

According to the present invention the desired electromagnetic spectrum LS3 can be predetermined to matches the relative intensities of LS1 at two or more selected wavelength of the visible light.

Preferably the coloring coating 22 has a transmission Tc in a range between 10% and 70%.

According to a preferred embodiment of the present invention the color effect of the coloring coating 22 results in a metallic appearance in the sense that the brightness of the surface of the coloring coating 22 and/or the front surface (1 FS) of the coated part 1 varies with the incidence angle of the ambient light impinging on the coloring coating.

According to a further preferred embodiment of the present invention the color effect of the coloring coating 22 results in a metallic appearance of the surface of the coloring coating 22 and/or the front surface 1 FS of the coated part 1 in the sense that a mean value of specular reflection of the visible spectrum of at least 20% is observed.

According to a further preferred embodiment of the present invention the color effect of the coloring coating 22 results in a metallic appearance in the sense that a grey reflection of the surface of the coloring coating 22 and/or the front surface 1 FS of the coated part 1 with CIE L*ab in the range of 40 to 99 with only small coloring of the reflected white light as given in CIE L*ab -5 < a* < 5; and/or -10 < b* < 10 is observed.

The coloring coating 22 can be deposited as single layer or as multilayer.

The coloring coating 22 has preferably a total thickness in a range of 10 nm to 200 nm. The coloring coating 22 preferably comprises at least one of the chemical elements selected from Cr, Zr, Al, In, Sn, Ti, Mo.

In order to attain different color effects, the coloring coating 22 can further comprise one or more chemical elements selected from nitrogen, carbon, oxygen, forming at least a nitride or at least a carbide, or at least an oxide, or combinations thereof.

Especial color effects can be achieved when the coloring coating 22 comprises at least one of the following compounds: Cr-Zr-N, Cr-Zr-C, Cr-Zr-C-N.

According to a further preferred embodiment the coloring coating 22 comprises a semiconductor material. In this embodiment the coloring coating can consist for example of one or more semiconductor layers. The semi-conductor layers can be radar- transparent or non-radar-transparent.

When the coloring coating 22 is deposited comprising a semiconductor material, the coloring layer 22 preferably comprises Ge and/or Si.

Preferably the coloring coating 22 is deposited by using physical vapor deposition techniques.

According to the present invention the substrate 10 can be set up as electromagnetic spectrum-adjusting means. In such a case the substrate 10 must be placed between the light source 2 and the coloring layer 22.

Preferably the substrate material is a kind of glass and/or plastic, or at least comprises a kind of glass and/or plastic.

In preferred embodiments the substrate material is polycarbonate or at least comprises polycarbonate.

According to the present invention at least one further component 50 can be used as electromagnetic spectrum-adjusting means, where the at least one further component 50 is placed between the light source 2 and the coloring layer 22.

According to the present invention at least one further at least one adjusting layer 60 can be used as electromagnetic spectrum-adjusting means, where the at least one adjusting layer 60 is placed between the light source 2 and the coloring layer 22. According to a preferred embodiment of the present invention, the coating system (20) comprises a base layer 21 deposited between the substrate 10 and the coloring coating 22 and/or a top layer 23 deposited atop the coloring coating 22, where the base layer 21 and/or the top layer 23 are preferably applied as one or more lacquer films.

When the coating system 20 comprises a top layer 23, this top layer 23 can be used as electromagnetic spectrum-adjusting means according to the present invention, where the top layer 23 is placed between the light source 2 and the coloring layer 22.

According to the present invention one or more adjusting means can be used. Some examples of means that can be used as electromagnetic adjusting means according to the present invention are: d) a lacquer, e) an ink, f) an ink jet, g) a plastic film, h) a plastic sheet, i) a lacquer system j) a foil, for example a foil applied by using a foil technology such as In Mold Decoration (IMD), k) a cubic, l) a printing, m) a further plastic component.

According to a preferred embodiment of the present invention, the electromagnetic spectrum-adjusting means comprise one or more organic and/or inorganic-pigment-types, and/or dyes in a concentration and ratio that allows adjusting the wavelength absorption and if given reflection for producing the adjusted electromagnetic spectrum LS2.

In an example of the directly above mentioned embodiment of the present invention, the electromagnetic spectrum adjusting means can be produced using a mixture of blue and red pigments. In this example the light source is a LED producing white light, hence LS1 corresponds to the spectrum of the white light. A component does not comprising electromagnetic spectrum-adjusting means is backlit with the light source and the transmitted light exhibits a non-adjusted electromagnetic spectrum LS2na having an orange color impression. The desired spectrum LS3 is a white light spectrum, i.e. LS3 = LS1. The inventors used first blue pigments for creating an adjusting layer to be used as electromagnetic spectrum-adjusting means. The resultant light spectrum was however not the white light spectrum but a light spectrum having a light blue color impression, i.e. | LS3 - LS*2| = delta xy > 0.1 , where LS*2 is a still not completely adjusted spectrum. Hence the inventors decided to modify the adjusting layer by adding further to the blue pigment also red pigments, in this manner obtaining an adjusted spectrum LS2 according to the present invention corresponding to the white light spectrum, i.e. . ILS3 - LS2I = delta xy < 0.1 , where LS3 = LS1. In this manner, the inventors created a component according to the present invention comprising electromagnetic spectrumadjusting means comprising a mixture of blue and red pigments in a suitable concentration for attaining the adjusted spectrum LS2 in the desired range according to the present invention.

When the coating system 20 is deposited between the substrate 10 and the light source 2, preferably the front surface 1 FS of the coated part 1 is coated with a further coating system 70, comprising one or more layers for providing wear resistance and/or corrosion resistance, and/or a decorative effect. For example, the coating system 70 can comprise at least one layer that modifies color tint of the front surface 1 FS of the coated part 1 .

Figure 1a schematically shows an example of a component according to the present invention having a coated part 1 and a substrate 10, the coating system 20 (schematically shown in Figure 1 b) comprising a coloring layer 22 and further comprising a top layer 23 and a base layer 21 - in this example the base layer 21 is optional. In this example the top layer 23 is used as electromagnetic spectrum-adjusting means.

Figure 2 schematically shows an example of a component according to the present invention having a further component 50 or and adjusting layer 60 as electromagnetic spectrum-adjusting means.

Figure 3 schematically shows an example of a component according to the present invention having a further component 50 or and adjusting layer 60 as electromagnetic spectrum-adjusting means, and additionally comprising a further coating system 70, for providing additional properties to the surface of the substrate 10 that would be exposed to the ambient if the further coating system 70 were not included. As already mentioned above the further coating system 70 can be for example a wear resistance layer. Figure 4 schematically shows an example of a component according to the present invention in which the substrate 10 is used as electromagnetic spectrum-adjusting means

Particularly preferred embodiments and examples of coated components according to the present invention, which comprise at least one semiconductor layer are explained in more detail below and some of them are described with the help of Figure 5 and Figure 6.

All examples of the invention in the present description should be understood as showcases of the invention and not as a limitation of the present invention.

According to a preferred embodiment of the present invention comprising a semiconductor layer, the component has a substrate that is a transparent or semitransparent glass or plastic component having a coating on a surface, the coated component comprising:

- at least one semiconductor layer,

- optionally a base layer and/or a top layer wherein: the component further comprises an adjustment layer as electromagnetic spectrum-adjusting means, wherein the adjustment layer is applied onto the surface of the transparent or semi-transparent component, wherein the adjustment layer comprises a polymer, a lacquer coating, a foil, a multi-layer system or complementary part with a given layer-arrangement and, wherein the coating is transparent to electromagnetic waves, i.e. it exhibits a low damping of less than 3 dB, the adjustment layer is selected in such a way that the light transmitted through the component and coating has a spectrum which is close to the spectrum of the source of light, wherein the transmitted spectrum matches the relative intensities of the source of light spectrum at two or more selected wavelength of the visible light.

According to a preferred embodiment of the present invention and illustrated in Figure 5, a semiconductor coating 202 is provided on the back side of a transparent or semitransparent plastic component 101 , wherein the semiconductor material comprises, Si, Ge, GaAs, either as pure materials or doped with other elements such a metals or semiconductors, wherein an adjustment layer 303 is provided on top of the semiconductor either in direct contact or close proximity to the semiconductor coating. The adjustment layer 303 comprises a polymer, lacquer coating, a foil, a multi-layer system or complementary part with a given layer-arrangement.

The back side of the component, also called "B-surface" B in Figure 5 is defined where the source of light 404 is placed, so that the surface of the component is facing the source of light. The other side, also called "A-surface" A in Figure 5 is the front side which is visible from the outside, such as the outside of a vehicle, for example. The transparent plastic component can be made of a colorless transparent polycarbonate, or other suitable polymer or can be a semi-transparent plastic component having any given color.

The adjustment layer 202 is selected in such a way that the transmission 505 of the spectrum of the source of light is kept similar to the original spectrum of the source of light. Therefore, the adjustment layer acts as a filter in order to adjust the transmission profiles of the spectrum of light from the source of light through the coating. Moreover the coating is semi-transparent when it is backlit but seems not transparent when it is not backlit by the light source by mostly reflecting the ambient visible light 606 and not transmitting the ambient visible light completely through the coating.

That way nothing can be seen through the coating when looking at the coating from the outside, but the light from the source of light on the back of the component can still be transmitted through the coating and according to the present embodiment of the invention not have a shifted color spectrum with respect to the original source of light spectrum due to the transmission of the semiconductor layer.

The source of light used for such applications comprises LED lights which have not a continuous spectrum compared to natural light. LED lights present one or more intensity peaks, or spectral bands at different wavelength of the spectrum. This is illustrated by Figure 6 which shows the vertical lines and wavelength which the LED is emitting the light, for example between 450 and 470 nm, 510 and 550 nm, and between 630 and 650 nm. The transmission of the semiconductor layer is shown by the curve having an increasing transmission as a function of the increasing wavelength. This would result in a shift of color in the red values and give a dimmed and orange color of the transmitted spectrum, which is aesthetically not appealing for the considered application. In this example, the adjustment layer is selected in such a way that it has a higher transmission for the lower wavelengths in order to compensate for the effect of the semiconductor transmission. In that example the adjustment layer is a lacquer layer, preferably a UV-hardened lacquer, comprising a mixture of at least two pigments, selected as example in the color spectrum blue-green and red, respectively. The resulting transmission of the plastic component, semiconductor layer and adjustment layer is shown as a "flatter" curve, at least in the region of the visible spectrum.

The spectrum of the transmitted light is therefore very close to the spectrum of the LED, or at least as average perception in the visible spectrum. It is clear in this example that the LED spectrum is the result of the superimposition of three different distinct wavelength bands and the resulting transmission has a continuous spectrum due to diffraction and transmission effects. However, the perception of the eye is sensitive to the average resulting spectrum of the LED and sees a white light even if it is a combination of three different wavelength. Therefore it can be said that the resulting spectrum of the light transmitted by the coating according to the present embodiment invention is a spectrum close to the one of the source of the light, at least in how it is perceived by the human eye. To be more precise, the resulting transmission curve must at least relatively cover the same intensities at selected emission spectrum of the source of light, here the emission bands of the LED.

The selection of the transmission of the adjustment layer is not limited to keep the spectrum of the white color of the source of light when transmitted through the plastic component, the semiconductor coating and the adjustment layer, but can be extended to all the colors provided by the source of light, i.e blue, red or green. The adjustment layer according to the present embodiment of the invention ensures that the original spectrum, or at least the original perception of the source of light is conserved when being transmitted through the coating.

According to another preferred embodiment of the present invention the adjustment layer can be the transparent or semi-transparent plastic component itself, wherein the semiconductor is applied on the front side (A-surface shown in Figure 5) and the light source placed so that the backside is facing the light source. Optionally adjustment layers such as lacquer can be added on top of the semiconductor layer. According to another embodiment of the present invention the adjustment layer can be applied on the front side (A-surface shown in Figure 5) of the transparent or semitransparent component, wherein the semiconductor is applied on top of the adjustment layer. An optional source of light could be placed in this configuration at the back side (B- surface shown in Figure 5) of the component. That way, the metallic shine is directly visible from the outside but can be backlit from behind and thank to the adjustment layer, the transmission is not affecting the spectrum of the source of light.

According to a further embodiment of the present invention, the adjustment layer can be a lacquer, preferably an UV-hardened lacquer, wherein several pigments comprising at least one, preferably two distinct colors are mixed into the lacquer and mixed using different emulsions in order to provide the correct spectral adjustment for the transmission of the spectrum through the coating, so that the transmitted spectrum through the coating and the component are close or similar to the spectrum of the source of light.