WO2020194144A1

WO2020194144A1 - Finish panel, finish assembly and furnishing item

Info

Publication number: WO2020194144A1
Application number: PCT/IB2020/052531
Authority: WO
Inventors: Denis MONZANI
Original assignee: Pel Plastic S.P.A.
Priority date: 2019-03-22
Filing date: 2020-03-19
Publication date: 2020-10-01
Also published as: EP3718784B1; IT201900004217A1; EP3718784A1

Abstract

The invention relates to a finish panel which comprises a front surface and a rear surface, wherein: - the front surface is smooth and, in use, is exposed to the sight of a user; - the rear surface, in use, is hidden from the sight of a user; - the finish panel thickness varies between a maximum and a minimum value in order to reproduce a predefined graphic solution, wherein the areas of the finish panel with minimum thickness correspond to the lighter areas of the graphic solution and the areas of the finish panel with maximum thickness correspond to darker areas of the graphic solution; and - the thickness is between 0.05 mm and 10 mm.

Description

FINISH PANEL, FINISH ASSEMBLY AND FURNISHING ITEM

DESCRIPTION

The present invention relates to a finish panel for furnishing items.

Here and below, the expression "furnishing item" means any item or device which, during its correct use, remains at least partially visible to a user who is in the same space in which the furnishing item itself is located. Therefore, such expression also includes items or devices which are not properly pieces of furniture but which, in the space considered, have been provided for a specific function, even very different, e.g. a structural function. By way of example, the space in which the furnishing items considered herein can be placed, can be a closed space such as the passenger compartment of a vehicle, the rooms of a house or the spaces of a building used for administrative, commercial or industrial purposes; or it can be an open space, such as a garden, an urban space, and so on. The furnishing items considered herein comprise a finish panel in polymeric material which extends over at least a part of their surface visible during use. Some of these furnishing items can therefore be, purely by way of example, a dashboard of a vehicle, an internal or external covering of a vehicle or of a building, a door, a piece of furniture or an architectural element inside or outside a building, a furnishing accessory, and so on.

Polymeric materials (commonly called plastic materials or even plastics) have various advantageous features which have made them very successful in many sectors. From the industrial point of view, the main advantage of polymeric materials lies in the fact that they can be processed with specific technologies which allow the production of a very large number of pieces at low costs. Moreover, polymeric materials are generally durable, resistant and lightweight.

Among the disadvantages of the use of polymeric materials, there is the fact that they are traditionally associated with medium-low quality products. In the past, fine finishes were made exclusively of materials such as wood, hide, leather, ceramic, glass, metals and the like.

The processing technologies and the formulations themselves of the polymeric materials are constantly evolving with the aim, among others, of giving the polymeric products high and very high quality finishes. In some cases, the polymeric materials are formulated and processed in order to simulate other materials of greater value. This therefore allows in some cases to replace valuable materials when their use is disadvantageous in terms of processability, supply, cost, safety and so on. Often the common user does not even notice the replacement, simply perceiving the high quality of the product.

Furthermore, an aesthetic taste inspired by high-tech solutions, which has given impetus to the development of further technical and aesthetic solutions, has recently developed. Such solutions allow to give polymeric materials also very high quality finishes, but without necessarily simulating a different material.

In the context of these recent developments, the possibility of obtaining a finish panel of high-quality polymeric material that can take two different visual configurations is perceived as desirable. Particularly, it would be desirable that a finish panel in polymeric material could switch, at will, from a first configuration, intuitively called "switched-off configuration", to a second configuration, called by contrast "switched-on configuration". More specifically, it would be desirable that the same finish panel which in some conditions has an even, solid and compact appearance, could assume, in other conditions, a different aspect in which an image, an inscription, a logo or a graphic solution is highlighted.

A similar solution can be obtained by means of known technologies for producing the displays commonly used in portable consumer electronic devices such as smartphones, tablets and the like. Such displays can for example be made using LCD ( Liquid Crystal Display), OLED ( Organic Light Emitting Diode) technologies or the like. Such a finish panel could be shaped quite freely and would have the possibility to switch at will from a switched-off configuration to a switched-on configuration. More specifically, in the switched-off configuration such a finish panel could have an even, solid and compact appearance, while in the switched-on configuration it could show images, inscriptions, logos or variable graphic solutions, even in motion, such as the reproduction of a photograph or a video. However, this solution implies an excessive degree of complication and production cost for the purposes of the finish panel of the invention. Therefore, the object of the present invention is to overcome the drawbacks underlined before with respect to the prior art.

Particularly, a task of the present invention is to make available a low-cost finish panel which in a switched-off condition has an even, solid and compact appearance, and which, in a switched-on condition, can show a static or predefined image, inscription, logo or graphic solution.

Such object and such tasks are achieved by means of a finish panel of polymeric material according to claim 1.

To better understand the invention and appreciate its advantages, some of its exemplifying and non-limiting embodiments are described below with reference to the accompanying drawings, wherein:

- Figure 1 schematically represents a front view of a finish panel according to the invention;

- Figure 2 schematically represents a side view of the finish panel of Figure 1 ;

- Figure 3 schematically represents an enlarged view of the detail referred to as III in Figure 1 ;

- Figure 4 schematically represents the sectional view made along the line

IV-IV of Figure 3, each one according to a different embodiment of the invention;

- Figure 5 schematically represents a possible sectional side view of a finish panel according to the invention;

- Figure 6 schematically represents an enlarged view of a detail similar to that referred to as VI in Figure 5; - Figure 7 schematically represents some possible views similar to that of Figure 6;

- Figure 8 schematically represents a perspective view of a finish panel according to the invention; and

- Figure 9 schematically represents a perspective view of another finish panel according to the invention.

In the context of the present discussion, some terminological conventions have been adopted in order to make reading easier and smoother. Such terminological conventions are clarified below.

First of all, the invention relates to a finish panel 20 which, during its correct use, is intended to be visible to an observer. In the following therefore“front” (A) refers to a position which, in the correct use of the finish panel 20, is relatively close to the observer. Likewise, rear (P) refers to a position which, in the correct use of the finish panel 20, is relatively far from the observer.

Moreover, there are some conventions and definitions which are widely used in the field of optics and lighting. These conventions and definitions are briefly reproduced below for the reader's convenience.

The way a person sees bodies around him/her depends on the interaction between light and matter. In particular, this study takes into account the optical properties of moulded plastic objects.

Whenever light passes through a separation surface between different materials (e.g. air-plastic or glass-air), a certain amount of light is reflected, a part is subject to surface scattering and another part is transmitted.

Inside the material, the portion of transmitted light may in turn be progressively reduced due to the absorption and volume scattering phenomena. In absorption, a photon is absorbed and then re-emitted in a non-radiative way, typically as heat. In atomic and molecular scattering, however, the photon is absorbed and then immediately re-emitted but with a variation in its propagation direction. Scattering can also occur due to structures of much larger dimensions than those of atoms or molecules. In volume scattering, this can occur due to the presence of particles of a foreign material dispersed in the main medium; in surface scattering, light deviation can be due to the microscopic morphology of the surface, as in the case of roughness and processing grooves, but also to the presence, for example, of small prisms, small lenses, bosses, or other alterations appropriately obtained on the surface of the medium.

Reflectance, absorption and scattering are properties of each material and depend on the wavelength of light across the respective spectrum. These properties can therefore be used to influence the colour of the light that interacts with the body.

In the case of pure absorption, the amount of light that passes through the material, /, given the initial flux b, can be described by the following equation (Lambert-Beer law):

/ = b exp(-£absCabst) = b exp(-at)

Eq. (1 )

The Lambert-Beer law states that the absorbance of a body depends on the length of the light path in the medium, t, on the concentration of the molecules or atoms responsible for absorption, c_abs, and on the molar extinction coefficient of the same elements, £_abs- It is the molar extinction coefficient that depends on the wavelength of light and this phenomenon is responsible for the colouring of bodies in the vast majority of cases. The product E_absC is the absorption coefficient a.

In case of pure volume scattering it is possible to describe the reduction of the luminous flux with the following equation:

I = b exp(-£scC_sct) = b exp(-ut)

Eq. (2) where £_sc is the molar scattering coefficient, c_sc is the concentration of scattering elements and a is called scattering coefficient. The two equations can be combined in the following expression, which takes into account both absorption and scattering: / = lo q-^(a+s>^{ = lo e^~kt

Eq. (3) where k is called extinction coefficient, or opacity. The transmittance T is defined as l/lo = exp{-kt) and represents the relative light quantity that passes through the material. T depends on the wavelength and this is the reason why the expression“transmittance spectrum” is used.

Total transparency, i.e. across the whole spectrum, can be quantified by the tristimulus luminance variable Y and can be calculated with the usual integration techniques applied to the product of the spectral density of incident radiation, S, times the aforementioned transmittance spectrum of the material, T, times the sensitivity curve of the human eye, y\

Using the above laws, it is possible to control the quantity and quality of the transmitted light by varying the thickness, the chemical composition of the medium, the concentration of dyes or dispersed particles that may be present and finally the surface texture of any body that allows the passage of light, and namely of moulded plastic bodies. The variation in thickness means a distribution of variable thickness, in the form of a difference in height or in any case of a non-flat surface or flat surface with non-coplanar segments. The surface with variable thickness can be either the one facing the observer or the one facing the opposite side, or both, but the case in which the surface with variable thickness is the one on the opposite side of the observer is of particular interest for this invention.

The light can be produced by an illuminator placed behind the moulded plastic material plate. The distribution of this light can be even, or uneven, and can be characterized by a colour, or be white.

Under these conditions, the thicker areas of the plate will appear darker than the thin ones, because a greater thickness t will correspond to them, and therefore a greater extinction (or opacity), according to equation (3), regardless of this being due to colouring or volume scattering. The thickness modulation therefore translates into a modulation of light intensity that reaches the observer, and the illumination map can be designed so as to offer the observer's eye a graphic or a drawing.

If the opacity of the plate is properly calibrated, then the embedded image will appear to the observer only when the rear illuminator is activated, while it will be invisible in other conditions. For example, the plate may appear completely black, or of a well-defined and opaque colour. For this reason, it is particularly useful that the surface with variable thickness is the one located on the opposite side of the observer.

As regards the scope of this application, the differences in height of the surface with variable thickness can vary between 0.05 and 10 mm. Some materials suitable for making the finish panel 20 are the polymers usually used in the optical field, such as for example polycarbonate, polymethyl methacrylate, copolymers of cyclic olefins, and the like. The absorption coefficient and the scattering coefficient can be chosen in such a way as to achieve a transparency between a minimum close to 0% and a maximum close to 100%, obtaining the maximum possible excursion in the brightness scale perceived by the observer. The maximum effectiveness of the proposed invention requires a low transparency value, less than 40%, in order to make the image invisible in the absence of backlighting.

A method suitable for experimentally measuring the transparency of an object is described below, for example in order to verify whether a finish panel 20 falls within the scope of the present invention. The method involves setting up an emitter and a light sensor in series. The emitter must be able to emit a collimated and concentrated light beam on the sensor. In turn, the sensor must be suitable for providing an indication of the intensity of the incident light. By turning on the emitter in the presence of air only between it and the sensor, the light beam will reach the sensitive area of the sensor substantially in its entirety, generating a signal that will be considered 100% of transparency. On the other hand, 0% transparency occurs when the sensor does not receive any fraction of the light beam. By interposing a body between the emitter and the sensor, the signal returned by the latter and scaled with respect to the 100% defined above provides the percentage of transparency considered here.

Surface scattering can be introduced to further modify the appearance of the device. If the surface facing the observer is perfectly shiny, there will be a strong reflectivity, with the additional effect of further masking the underlying design. However, this surface can also be rough or in any case capable of scattering, if it is considered more useful or necessary to offer the user this type of finish. In this case, the absorption and volume scattering must be dosed so as to ensure the non-visibility of the design.

All the phenomena described above can be suitably used in order to obtain a desired aesthetic effect for an observer looking at a backlit, side-lit or front-lit plastic body.

The combination of thickness and concentration of the dyes and the characteristics of volume and/or surface scattering will determine a sharp transmittance variation, which will be recognized by the observer as a variation in brightness, and therefore as a design or graphic.

A particular application of these phenomena is the production of a suitably loaded and coloured finish panel 20, so that it will appear even and opaque in the absence of backlighting, while, in the presence of backlighting, the graphics obtained by means of the phenomena described above will be revealed in transparency.

The invention relates to a finish panel 20 which comprises a front surface

22 and a rear surface 24, wherein:

- the front surface 22 is smooth and, in use, is exposed to the sight of a user;

- the rear surface 24, in use, is hidden from the sight of a user;

- the finish panel 20 thickness t1 varies between a maximum and a minimum value in order to reproduce a predefined graphic solution, wherein the areas of the finish panel 20 with minimum thickness correspond to the lighter areas of the graphic solution and the areas of the finish panel 20 with maximum thickness correspond to darker areas of the graphic solution; and

- the thickness is between 0.05 mm and 10 mm.

Preferably, according to the invention, the areas of the finish panel 20 with minimum thickness have a transparency of less than 40%.

Preferably, according to the invention, the areas of the finish panel 20 with minimum thickness have a transparency of less than 35%.

Preferably, according to the invention, the areas of the finish panel 20 with minimum thickness have a transparency of less than 30%.

Preferably, according to the invention, the areas of the finish panel 20 with minimum thickness have a transparency of less than 25%.

Preferably, according to the invention, the areas of the finish panel 20 with minimum thickness have a transparency of less than 20%.

Preferably, according to the invention, the areas of the finish panel 20 with maximum thickness have a transparency close to 0%.

As the skilled person can well understand, since the front surface 22 is smooth and the thickness of the finish panel 20 is variable, the rear surface 24 is characterized by level variations.

According to the different possible embodiments of the invention, the finish panel 20 can be flat (see, e.g., Figures 2 and 5), it can have a simple curvature (see, e.g., Figure 8) or a more complex shape, such as for example a double curvature (see, e.g., Figure 9).

Preferably, the finish panel 20 is made from a transparent, semitransparent or opalescent material. Preferably, the finish panel 20 is made from a polymeric material or from glass.

Preferably, the finish panel 20 is coupled to a lighting panel 26 which can alternatively take a switched-on configuration and a switched-off configuration and which will be described in detail below.

The transparency values indicated above are sufficiently low because in the switched-off configuration, i.e. in the absence of a backlighting, the finish panel 20 appears even, solid and compact, and gives the impression of having a massive structure.

The light coming from the environment in which the observer is immersed can in fact pass through the finish panel 20 to a minimum, especially in areas with minimum thickness. In turn, the minimum part of light which passes through the finish panel 20 can be reflected only in part by the lighting panel 26 or by any other component which is behind the finish panel 20. The amount of light that was reflected is therefore so small that it cannot reasonably pass through the finish panel 20 again, due to its low transparency.

In this way, in the switched-off configuration, the finish panel 20 appears as if it does not include any graphic solution.

At the same time, however, the transparency levels of the finish panel 20 are such that, in the switched-on configuration, i.e. in the presence of an adequate backlighting, the light radiation that reaches the rear surface 24 of the finish panel 20 passes through the latter with variable intensity. More specifically, the maximum transparency areas appear as the lightest areas of the graphic solution, while the minimum transparency areas (which can also be completely opaque) appear as the darkest areas of the graphic solution.

Preferably, the finish assembly 28, comprising the finish panel 20 and the related lighting panel 26 are integrated into a furnishing item, so that, in the correct use, the front surface 22 of the finish panel 20 is exposed to the view of an observer. Preferably, if the lighting panel 26 requires electrical power to be able to switch from the switched-off configuration to the switched-on configuration, the power line is integrated into the furnishing item and appears hidden while in use.

Depending on the specific graphic solution, the thickness t1 of the finish panel 20 in the different areas can vary with a substantial continuity between the minimum thickness and the maximum thickness. In this way, the finish panel 20 can reproduce a graphic solution that requires an almost continuous variation in brightness between the different areas. The graphic solution of the finish panel 20 can thus reproduce, for example, a black and white photograph (see, e.g., Figure 5).

In other cases, on the other hand, the thickness t1 of the finish panel 20 in the various areas can assume a finite number of values between the minimum thickness and the maximum thickness. In this way, the finish panel 20 can reproduce a graphic solution that requires sharp variations in brightness between the different areas. The graphic solution of the finish panel 20 can thus reproduce, for example, a logo or an inscription (see, e.g., Figure 1 and 3-4).

In accordance with the invention, the transparency values of the finish panel 20 can be predefined during project development thanks to the variation of some parameters which are described below.

Preferably the finish panel 20 is made with an injectable polymer. As an example, some materials suitable for the production of the finish panel 20 are: polycarbonate (PC), polymethylmethacrylate (PMMA) or other acrylate, amorphous copolyester (PETG, PCTA, PCTG), cyclic olefins copolymers (COC), polyurethane (PU), polystyrene (PS), polypropylene (PP), a mixture of polycarbonate and acrylonitrile butadiene styrene (PC-

ABS) or other transparent technopolymers. Some of these materials are widely appreciated for their high transparency. Other materials, on the other hand, usually have a semi-transparent or opalescent appearance.

For the purposes of the present invention, however, the transparency of the finish panel 20 must be limited in a controlled way, and this can be achieved by acting on some parameters. The parameters on which it is preferable to act are the thickness t1 of the finish panel 20 and the addition of an opacifying filler dispersed in the mass of the base material. Another way to limit transparency could be the addition of a surface opacifying layer 30, such as the deposition of a coloured layer (like in sunglasses lenses) or a semi-reflective layer (like in mirror sun lenses). In this regard, consider Figures 1 , 3 and 4. Such Figures schematically illustrate, respectively in a front view, in a detail view and in a sectional view, a finish panel 20 according to the invention which shows a graphic solution. Such graphic solution, simplified for greater clarity, includes lighter areas and darker areas. While the lighter areas are obtained by giving the minimum thickness to the material which composes the finish panel 20, the darker areas can be obtained in different ways.

Figure 4. a schematically shows an embodiment of the invention wherein the darker areas of the graphic solution are obtained by giving the maximum thickness to the material composing the finish panel 20.

Figure 4.b schematically shows an embodiment of the invention wherein the darker areas of the graphic solution are obtained by applying a surface opacifying layer 30 on the rear surface 24 of the finish panel 20.

Figure 4.c schematically shows an embodiment of the invention wherein the darker areas of the graphic solution are obtained with a mixed system between the previous solutions, i.e., both by giving a high thickness to the material which composes the finish panel 20, and applying a surface opacifying layer 30 on the rear surface 24 of the finish panel 20.

Figure 4.d schematically shows an embodiment of the invention wherein the graphic solution as a whole is obtained by applying on the back of the finish panel 20 a transparent sheet 32 on which the graphic solution itself is at least partially reported, e.g. by printing, painting, screen printing or the like.

Other ways to vary the transparency of the finish panel 20 can be the controlled addition of an opacifying or scattering filler in the material volume, or the surface treatment of the front surface 22 or of the rear surface 24 of the finish panel 20, e.g., by satin finishing or the like.

According to some embodiments, the front surface 22 of the finish panel 20 can also be treated in order to give it a metallic appearance. Such effect can be obtained by means of different processes known per se, for example from the sector of the lens treatment for sunglasses. A metallic finish on the front surface 22 can be obtained, e.g., by painting with a semitransparent paint with suspended metal particles, vacuum metallization, aluminizing, sputtering or galvanic deposit. This type of treatment gives the finish panel 20, in the absence of backlighting, a uniform, solid, compact and metallic appearance.

As mentioned above, for technological and size reasons, the thickness t1 of the finish panel 20 is limited to 10 mm or less. Therefore, an opacifying filler, i.e. consisting of absorbent and/or scattering particles, is preferably used. Such particles are known in the optics sector.

Preferably, the particles of the opacifying filler are evenly dispersed in the transparent base material.

For the purposes of the present invention, in the design of the finish panel 20, it is necessary to define the base material to be used in the injection mould. Subsequently, it is necessary to define the maximum and minimum thicknesses of the finish panel 20 on the basis of the technological and size limits that derive from the use for which the finish panel 20 is intended. Subsequently, once the type of filler to be used has been chosen, it is necessary to define the filler concentration necessary to limit the transparency of the areas of minimum thickness of the finish panel 20 within the desired limits.

The finish panel 20 according to the invention is preferably obtained by injection moulding of a polymeric material. The advantages deriving from the use of this process and of this material are widely known and have been briefly described in the introductory part of this discussion.

A particular advantage relating to the present invention resides in the fact that the thickness variation of the finish panel 20 can be obtained thanks to the precision manufacturing of the mould. This processing can be obtained using different technologies such as: laser processing, plasma processing, numerical control milling by means of mini-milling cutters, electrical discharge machining (EDM), chemical milling or chemical etching. Once the desired mould is obtained, the injection moulding allows the production of a very high number of pieces at a very low cost with a high quality and a minimum error margin.

Alternatively, the finish panel 20 according to the invention can also be obtained by other processing technologies, such as for example extrusion, compression moulding, thermoforming and the like.

As the skilled person can well understand, the effect obtained by the finish panel 20 of the invention is similar to that obtained with the lithophane technique. Compared to this known technique, however, the present invention includes some important differences. First of all, the polymeric materials used allow the production of the finish panel 20 by means of the injection moulding technique which allows the rapid production of a very large number of pieces. This potential of injection moulding is particularly important in industrial sectors such as the automotive sector where the same finish panel 20 must be made available quickly and in a very large number of specimens (in the order of hundreds of thousands). The skilled person can well understand that the lithophane technique, whether it is carried out in a traditional way with ceramic material or by 3D printing with polymeric material, in any case cannot guarantee the times, costs and number of pieces required by the automotive sector at all.

Furthermore, in the lithophane, in order to make the image clear, the variations in thickness are all reported on the front surface exposed to view, while the rear surface which is affected by the light radiation is smooth. This certainly determines, although imprecisely, the visibility of the graphic solution, even in the switched-off configuration.

As already mentioned above, according to some embodiments, the finish panel 20 also comprises a lighting panel 26, thus constituting a finish assembly 28. The lighting panel 26 is coupled (i.e. matched) to the rear surface 24 of the finish panel 20 and is suitable for alternately taking a switched-on configuration and a switched-off configuration.

In the switched-on configuration the lighting panel 26 is suitable for providing a backlighting of the finish panel 20, i.e., it is suitable for producing or conveying a light radiation so that it reaches the rear surface 24 of the finish panel 20. Preferably, the light radiation of the backlighting obtained through the lighting panel 26 is distributed in a substantially uniform way over the whole extension of the graphic solution of the finish panel 20.

In the switched-off configuration, the lighting panel 26 does not provide any backlighting of the finish panel 20.

Preferably, the lighting panel 26 includes in turn a lighting body 34. Advantageously, the lighting panel 26 receives the light radiation emitted by the lighting body 34 and guides it so as to distribute it homogeneously and uniformly on the surface of the finish panel 20.

The lighting panel 26 and the way in which it manages to guide the light in the desired way will be described in detail below.

Preferably the lighting body 34 has a predominantly linear conformation. For example, such conformation can be obtained by a plurality of LEDs {Light Emitting Diodes). The advantage of LEDs is that, during designing, they can be arranged in arrays shaped with great freedom. For use in combination with the lighting panel 26 of the invention, the preferred arrangement of the LEDs is that which forms a strip, so as to obtain the predominantly linear conformation desired for the lighting body 34. In alternative or in addition, a lighting body 34 with a predominantly linear conformation can be obtained by means of a remote light source from which a bundle of optical fibres departs. In such case, the ends of the optical fibres distal to the light source should be arranged in a row which extends along the side of the lighting panel 26, preferably approaching it with a course perpendicular to the side itself.

Still, a further embodiment of the lighting body 34 can advantageously comprise a laser light source.

Thanks to the predominantly linear conformation, the lighting body 34 can be arranged along one side of the lighting panel 26, so as to introduce the maximum quantity of light in the thickness t2 of the lighting panel 26 itself (see Figure 5).

In order to collect, guide and emit as much light as possible, it is preferable to maximize the transparency of the lighting panel 26. For example, unlike what happens for the finish panel 20, it is preferable that no opacifying, absorbent or scattering fillers are dispersed in the mass of the base material, which fillers would limit its transparency.

Preferably the lighting panel 26 is made with a transparent and injectable polymer. As an example, some materials suitable for the production of the lighting panel 26 are: polycarbonate (PC), polymethylmethacrylate (PMMA) or other acrylate, amorphous copolyester (PETG, PCTA, PCTG), cyclic olefins copolymers (COC), polyurethane (PU), polystyrene (PS), polypropylene (PP), a mixture of polycarbonate and acrylonitrile butadiene styrene (PC-ABS) or other transparent technopolymers.

The lighting panel 26 is therefore intended to receive the light from the lighting body 34, preferably arranged on one side, to guide it through its own mass, and to emit it in a distributed way from its surface facing the finish panel 20. Since the light output of the lighting body 34 is limited by external factors, it is good to maximize the efficiency of the lighting panel 26, in order to maximize the amount of light made available towards the finish panel 20. For this purpose, it is advantageous to adopt solutions which limit light leaks in unwanted directions. For example, it is advantageous to provide a reflective layer 36 on the surfaces of the lighting panel 26 from which it is not desirable for the light to escape. Typically, it is advantageous to provide a reflective layer 36 on the rear surface of the lighting panel 26 (see Figure 7.e) and on the sides which are not coupled to the lighting body 34.

For technological and dimension reasons, the thickness t2 of the lighting panel 26 should preferably be limited within 30 mm, even more preferably within 10 mm. The way in which the lighting panel 26 is able to extract the light and emit it in the desired way is described below.

It is known that a light radiation introduced into a transparent body propagates within the mass of the material which constitutes it, bouncing from one wall to another. This internal propagation allows the light emitted by the lighting body 34 to be made available within the whole lighting panel 26. The problem faced by the Applicant was the extraction of the light with the desired distribution to best illuminate the graphic solution reproduced on the finish panel 20.

In order to extract the light from the inside of the lighting panel 26, the Applicant has studied the arrangement of special bumps 38 wherein each of such bumps 38 introduces a perturbation in the internal propagation of the light, with the result of directing a portion of light radiation outwards (see Figure 7. a).

Preferably the bumps 38 are arranged on the rear surface 40 of the lighting panel 26 and are able to direct a portion of light radiation towards the front surface 42 (i.e. towards the surface opposite to that on which the bumps 38 are arranged).

The bumps 38 can be characterized by very different shapes, dimensions, distributions, a description of which will be given below by way of example, with specific reference to Figures 6 and 7.

The bumps 38 preferably have a dome conformation. The Applicant has studied such conformation and has found that it achieves the desired effect of perturbing the internal propagation of the light to deflect a portion thereof.

More specifically, the bumps 38 can have the shape of a sphere portion, or an ellipsoid portion, or another rotation solid portion as for example a paraboloid or even composite shapes obtained from different solid portions. Such shapes are described here without any limiting intent and it will be clear to the skilled person that other shapes can be designed for bumps 38 to meet specific needs. Each individual bump 38 can have a height h (measured in a direction perpendicular to the surface of the lighting panel 26) between about 20 pm and about 300 pm. Furthermore, each individual bump 38 can have a characteristic dimension d (measured in a direction parallel to the surface of the lighting panel 26, for example the diameter) between about 50 pm and about 300 pm.

More in detail, by way of example, Figures 6, 7. a and 7.e show a hemispherical bump 38, wherein the bump 38 is obtained from a half sphere where, therefore, the height h is equal to half the diameter d. Figure 7.b shows a bump 38 obtained from a spherical cap wherein the height h is less than half the diameter d. Figure 7.c shows a bump 38 obtained from an ellipsoid cap, wherein the height h is less than half the diameter d. Figure 7.d shows a bump 38 obtained from an ellipsoid cap, wherein the height h is greater than half the diameter d. Figure 7.f shows a bump 38 obtained by the composition of two different caps.

To obtain an effective extraction of the light, a suitable number of bumps 38 must be set up on the surface of the lighting panel 26. For example, the overall surface occupied by the bumps 38 can represent a percentage between 5% and 60% of the overall surface of the lighting panel 26.

The characteristics of the bumps 38 can vary within a single lighting panel 26 according to the invention. In fact, the intensity of the light radiation available in the close proximity of the lighting body 34 is considerably greater than that available far from it. For this reason, for example in order to obtain an illumination as uniform as possible over the whole surface of the lighting panel 26, it is possible to compensate for the different intensity of light radiation by varying the shapes and/or dimensions and/or density of the bumps 38 when moving away from the lighting body 34.

By way of example, it can be considered that, in the design of a lighting panel 26, it is decided to use only one type of standard bump 38, having defined shapes and dimensions. In this case the distribution of the illumination can be managed by varying the density of the bumps 38 per surface unit of the lighting panel 26. For example, the density may vary from a minimum value in the close proximity of the lighting body 34, up to a maximum value in the areas furthest from the lighting body 34. In fact, although in this hypothesis all the bumps 38 are the same, those closest to the lighting body 34 will have a greater quantity of light available and, therefore, each of them will be able to deflect a greater quantity. On the contrary, the bumps 38 further away from the lighting body 34 will have a significantly lower quantity of light available and, therefore, each of them will be able to deflect a much smaller quantity.

A similar compensation effect could for example be obtained by varying the shape and/or dimensions of the bumps 38 as the distance from the lighting body 34 increases. However, the variation in density is preferable because it can occur within a very wide range of values with very significant effects.

In addition to the distance from the lighting body 34, other factors can also affect the propagation inside the lighting panel 26 and therefore the intensity of the light radiation available in the various areas of the lighting panel 26 itself. One of these factors is the thickness 12 of the lighting panel 26 and therefore the section useful for the passage of light. In detail, the thickness 12 of the panel near the lighting body 34 significantly affects the quantity of light that can be introduced into the lighting panel 26 itself, while any subsequent decrease in thickness determines a reduction in the quantity of light available in areas which are far from the lighting body 34. For this reason, it is preferable that, if it is desired to vary the thickness 12 of the lighting panel 26, this will decrease with the distance increase from the lighting body 34.

Another factor affecting the internal propagation of light is the possible curvature of the lighting panel 26. As already mentioned above, the lighting panel 26 (and also the finish panel 20), can have a flat development (Figures 2 and 5), or a development with a simple curvature

(Figure 8), or a development with a double curvature (Figure 9). The greater the curvature and the lesser the amount of light that can be made available in areas far from the lighting body 34.

In view of what has been described above and for the purposes of the present invention, in the design of the lighting panel 26, it is necessary to define the material and the overall shape and shape of the lighting panel 26. Next, it is necessary to define the shape, dimensions and density of the bumps 38.

The lighting panel 26 according to the invention is preferably obtained by injection moulding of a polymeric material. The advantages deriving from the use of this process and of this material are widely known and have been briefly described in the introductory part of this discussion.

A particular advantage relating to the present invention resides in the fact that any specific distribution of the bumps 38 on the lighting panel 26 can be obtained thanks to the precision manufacturing of the mould. This processing can be obtained using different technologies such as: laser processing, plasma processing, numerical control milling by means of mini-milling cutters, EDM, chemical milling or chemical etching. Once the desired mould is obtained, the injection moulding allows the production of a very high number of pieces at a very low cost with a high quality and a minimum error margin.

Alternatively, the lighting panel 26 according to the invention can also be obtained by other processing technologies, such as for example extrusion, compression moulding, thermoforming and the like.

The overall thickness T of the finish assembly 28, comprising the finish panel 20 and the lighting panel 26, is preferably between 0.6 mm and 60 mm, even more preferably between 0.6 mm and 20 mm. It should be noted that the lighting body 34, if any, is also included within this overall thickness T (see Figure 5).

According to some embodiments, the finish assembly 28 is coupled to a rear shell suitable for preventing any backlighting of the panel, that is, it is suitable for shielding the light radiation that could reach the rear surface of the panel. In other embodiments, such shielding is provided by the furnishing item inside which the finish assembly 28 is arranged. The shielding (given by the shell and/or by the furnishing item) prevents the graphic solution from being accidentally visible in the switched-off configuration due to the ambient brightness.

According to some embodiments, the whole finish assembly 28 can be made by means of the multi-injection moulding technology, known per se. According to such technology, a single mould with movable parts allows to mould different components by injecting different materials. For example, according to this embodiment, in a first moulding configuration the mould can receive the injection of the material intended to constitute the finish panel 20. Subsequently, the mould can take a second moulding configuration wherein it can receive the injection of the material intended to constitute the lighting panel 26. In this way it is possible to obtain the whole finish assembly 28 already assembled, without any need to move and handle the individual components. In an equally manner known per se, the multi-injection moulding also allows the possible moulding of further components, such as for example the shell described above and/or an elastomeric gasket or the like.

As the skilled person can easily understand, the invention allows to overcome the drawbacks highlighted above with reference to the prior art. Particularly, the present invention makes available a low-cost finish panel 20 which in a switched-off condition has an even, solid and compact appearance, and which, in a switched-on condition, can show a static and predefined graphic solution.

It is clear that the specific features are described in relation to various embodiments of the invention with exemplifying and non-limiting intent. Obviously, a person skilled in the art may make further modifications and variations to this invention, in order to meet contingent and specific requirements. For example, the technical features described in connection with an embodiment of the invention may be extrapolated from it and applied to other embodiments of the invention. Furthermore, such modifications and variations are included within the scope of protection of the invention, as defined by the following claims.

Claims

1. Finish panel (20), comprising a front surface (22) and a rear surface (24), wherein:

- the front surface (22) is smooth and, in use, is exposed to the sight of a user;

- the rear surface (24), in use, is hidden from the sight of a user;

- the finish panel (20) thickness varies between a maximum and a minimum value in order to reproduce a predefined graphic solution, wherein the areas of the finish panel (20) with minimum thickness correspond to the lighter areas of the graphic solution and the areas of the finish panel (20) with maximum thickness correspond to darker areas of the graphic solution; and

- the thickness t1 is between 0.05 mm and 10 mm.

2. Finish panel (20) according to claim 1 , wherein the areas of the finish panel (20) with minimum thickness have a transparency of less than 40%.

3. Finish assembly (28), comprising a finish panel (20) and a lighting panel (26) coupled to the rear surface (24) of the finish panel (20) and suitable for alternatively taking a switched-on configuration and a switched-off configuration.

4. Finish assembly (28) according to claim 3, wherein the lighting panel (26) comprises a lighting body (34).

5. Finish assembly (28) according to claim 3 or 4, wherein the finish panel (20) and/or the lighting panel (26) are made of polymeric material.

6. Finish assembly (28) according to claim 5, wherein the polymeric material is selected from the group comprising: polycarbonate (PC), polymethylmethacrylate (PMMA) or other acrylate, amorphous copolyester (PETG, PCTA, PCTG), cyclic olefins copolymers (COC), polyurethane (PU), polystyrene (PS), polypropylene (PP), a mixture of polycarbonate and acrylonitrile butadiene styrene (PC-ABS). 7. Finish assembly (28) according to claim 5 or 6, wherein the finish panel

(20) and/or the lighting panel (26) are made by injection moulding.

8. Finish assembly (28) according to one or more of claims 3 to 7, wherein the thickness t2 of the lighting panel (26) is comprised within 30 mm, preferably within 10 mm.

9. Finish assembly (28) according to one or more of claims 3 to 8, wherein the overall thickness T of the finish assembly (28) is comprised between 0.6 mm and 60 mm.

10. Finish assembly (28) according to one or more of claims 3 to 8, wherein the overall thickness T of the finish assembly (28) is comprised between 0.6 mm and 20 mm. 1 1. Finish assembly (28) according to one or more of claims 4 to 10, wherein the lighting body (34) is arranged along one side of the lighting panel (26), so as to introduce the light in the thickness t2 of the lighting panel (26). 12. Finish assembly (28) according to one or more of claims 3 to 1 1 , wherein the lighting panel (26) comprises a plurality of bumps (38), and wherein each bump (38) introduces a perturbation in the propagation of the light inside the lighting panel (26). 13. Finish assembly (28) according to claim 12, wherein the bumps (38) have a dome conformation. 14. Finish assembly (28) according to claim 12 or 13, wherein each bump (38) has a height h comprised between about 20 pm and about 300 pm. 15. Furnishing item comprising a finish panel (20) according to claim 1 or 2 and/or a finish assembly (28) according to one or more of claims 3 to 14.