Transparent, multi-layer screen for projecting RGB images and method for making the same

Abstract

A method for making a multi-layer screen (1), comprising the steps of: - providing a transparent first layer (2), - depositing on the first layer (2) a first portion (3a) of a transparent intermediate layer (3) exhibiting a micro-lenticular shaped surface (4) defining a plurality of micro-lenses, and - depositing at least one reflective element (5) at the shaped surface (4) of the first portion (3a) of the intermediate layer (3), which is configured to partially cover at least one micro-lens of the plurality of micro-lenses obtained from the previous step, - depositing a second portion (3b) of the intermediate layer (3) on the shaped surface (4) of the first portion (3a) of the intermediate layer (3), which is partially covered by the at least one reflective element (5) obtained from the previous step, - covering the second portion (3b) of the intermediate layer (3), obtained from the previous step, with a transparent second layer (7).

Description

[0001] Title: “Transparent, multi-layer screen for projecting RGB images and method for making the same”

[0002] DESCRIPTION

[0003] Technical field

[0004] The present invention relates to a multi-layer screen and a method for making a multi-layer screen. More specifically, the present invention develops in the technical field of transparent screens on which an RGB image is projected, whether fixed for displaying information content in museums or shop windows, or intended for use as head-up displays in vehicles for displaying both information and / or images on the screen and what is beyond the screen.

[0005] Background art

[0006] Screens for displaying images are known in the background art. The screens of the known art are multi-layers comprising a substrate, a first shaped optical layer, a reflective layer, a second optical layer, and a protective layer. The substrate is made as a sheet and exhibits optical transparency. The first optical layer is shaped, formed at the substrate, exhibits optical transparency, and comprises a plurality of lenses. The reflective layer is formed on the first optical layer and is a semi-transmissive reflective layer reflecting part of the incident light and transmitting the remaining part.

[0007] A screen for displaying images comprising a plurality of Fresnel lenses, i.e., much larger sections of lenses focusing light on one specific point, thereby allowing the image to be viewed only from a pre-determined position, is known from the Document EP 3825765 Al.

[0008] Furthermore, the Document US 2014 / 198368 Al shows a screen for displaying images comprising a plurality of reflective elements, distributed at an array of microlenses. However, these reflective elements are rotated so as to have different axes depending on their position on the screen, thereby maximizing the visibility of the image from a specific position.

[0009] SUMMARY OF THE INVENTION Object of the invention

[0010] In this context, the technical task underlying the present invention is to provide a multi-layer screen and a method for obtaining a multi-layer screen, such as for head- up displays, as an alternative to the known art.

[0011] Furthermore, an object of the present invention is to provide a multi-layer screen and a method for making a multi-layer screen, wherein the transparency and the brightness of the multi-layer screen thus obtained are modulable, without distortion of the light transmitted from the outside.

[0012] The stated technical task and specified objects are substantially achieved by a method comprising the technical features set forth in one or more of the appended claims.

[0013] Advantages of the invention

[0014] Thanks to an embodiment, it is possible to obtain a multi-layer screen and a method for making a multi-layer screen having a wide display angle. Advantageously, this allows a user to have a greater positioning freedom with respect to the multi-layer screen.

[0015] Still advantageously, the screen made according to the method of the present invention allows the transparency and brightness of the multi-layer screen to be modulated since it has a plurality of reflective elements covering a micro-lenticular configuration.

[0016] LIST OF THE FIGURES

[0017] Further features and advantages of the present invention will become more apparent from the indicative, and therefore non-limiting, description of a preferred, though not exclusive, embodiment of a method for making a multi-layer screen, such as for head-up displays, as illustrated in the accompanying drawings, in which:

[0018] - Figures la-lb show the steps of a method for obtaining a multi-layer screen according to the present invention,

[0019] - Figure 1c is a side sectional view of the multi-layer screen according to the present invention,

[0020] - Figure 2 is a top sectional view of the multi-layer screen according to a first embodiment;

[0021] - Figure 3 is a top sectional view of the multi-layer screen according to a second embodiment,

[0022] - Figure 4 is a top sectional view of the multi-layer screen according to a third embodiment,

[0023] - Figure 5 is a top sectional view of the multi-layer screen according to a fourth embodiment;

[0024] - Figure 6 is a top sectional view of the multi-layer screen according to a fifth embodiment.

[0025] DETAILED DESCRIPTION

[0026] The object of the present invention is a method for making a multi-layer screen 1 which can be used for displaying information content in museums, shop windows and other locations, or as an alternative for head-up displays in vehicles for displaying both information and / or images on the screen and what is beyond the screen.

[0027] The method comprises a step of providing a first transparent layer 2 which is preferably rigid. Preferably, the first layer 2 is made of glass in the rigid version of the screen. Alternatively, in the flexible version, the first layer 2 is preferably made of a material selected from polycarbonate, polyethylene terephthalate, acrylic glass (polymethylmethacrylate).

[0028] Within the scope of the present invention, reference is made several times to a transparent layer which is understood as a layer provided with optical transparency, as the multi-layer screen is intended for use in a variety of applications where the possibility of seeing beyond the screen is required, such as for displaying contents / information on shop windows or for the specific use for head-up displays.

[0029] Next, the method comprises a step of depositing on the first layer 2 a first portion 3a of a transparent intermediate layer 3 exhibiting a micro-lenticular shaped surface 4 defining a plurality of micro-lenses. Preferably, the first portion 3 a of the intermediate layer 3 is made of epoxy photo-polymerizable resin, or of a polysiloxane-based, organic / inorganic, hybrid photo-polymerizable polymer.

[0030] Preferably, the shaped surface 4 has a plurality of convexities at each microlens.

[0031] Within the scope of the present invention, micro-lenticular shaped surface means a surface having spherical cap-shaped protrusions, all having the same or similar shape and size, which are arranged according to an orderly geometry and close to each other so as to maximize their packing. This allows a wide display angle of the multilayer screen 1 to be obtained, thereby allowing a user to have a greater positioning freedom with respect to the multi-layer screen 1 itself.

[0032] The method comprises a further step of depositing at least one reflective element 5 at the shaped surface 4 of the first portion 3a of the intermediate layer 3, which is configured to partially cover at least one micro-lens of the plurality of micro-lenses obtained from the previous step.

[0033] Preferably, the step of depositing at least one reflective element 5 is implemented by spray coating or evaporation. Preferably, when the at least one reflective element 5 is deposited by spray coating, a reflective metal or a reflective ink is used. According to an embodiment, the reflective ink contains metal nanoparticles. Still preferably, when the at least one reflective element 5 is deposited by evaporation, a reflective metal is used. More preferably, the used reflective metal is selected from noble metals, such as copper, gold, and silver, or transition metals, such as aluminum and nickel, or vacuum-evaporable metals, such as aluminum. Still preferably, the step of depositing at least one reflective element 5 is implemented by micro-contact stamping. The micro-contact stamping involves the application of a micro-structured mold, covered by a reflective material, on the shaped surface 4. Preferably, the micro-contact stamping involves the use of reflective ink.

[0034] The method comprises a step of depositing a second portion 3b of the transparent intermediate layer 3 on the shaped surface 4 of the first portion 3a of the intermediate layer 3, which is partially covered by at least one reflective element 5, obtained from the previous step. Preferably, the second portion 3b of the intermediate layer 3 is made of epoxy photo-polymerizable resin, or of a polysiloxane-based, organic / inorganic, hybrid polymer.

[0035] The method comprises a following step of providing a transparent second layer 7. Preferably, the second layer 7 is made of a material selected from glass, polycarbonate, polyethylene terephthalate, acrylic glass (polymethylmethacrylate).

[0036] The method comprises a further step of covering the second portion 3b of the intermediate layer 3, obtained from the previous step, with the second layer 7, thereby completing the multi-layer.

[0037] Hereinafter, embodiments of the invention for depositing the at least one reflective layer 5 will be described.

[0038] According to a first embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of: covering the shaped surface 4 of the first portion 3 a of the intermediate layer 3 with a shadow mask, depositing a reflective material layer on the shaped surface 4 covered by the shadow mask obtained from the previous step, and removing the shadow mask.

[0039] Preferably, the reflective material layer is deposited by spray coating or evaporation.

[0040] Still preferably, the reflective material of the reflective material layer is a reflective metal or a reflective ink. Still preferably, the shadow mask has at least one hole having a size in the range of micrometers. Preferably, the at least one hole has a circular shape. Still preferably, the shadow mask has a plurality of holes.

[0041] According to this first embodiment, the at least one reflective element 5 is obtained on the shaped surface 4 at the at least one hole of the shadow mask.

[0042] According to a second embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of depositing a reflective material layer on the shaped surface 4 of the first portion 3a of the intermediate layer 3, etching, i.e. selectively etching, the reflective material layer by placing a mold soaked in a corrosive solution on the reflective material layer, removing the mold.

[0043] Preferably, the reflective material of the reflective material layer is a reflective metal or a reflective ink or a dielectric material, such as an oxide multi-layer.

[0044] Still preferably, the mold has at least one protrusion having a size in the range of micrometers. Preferably, the at least one protrusion has a circular shape. In detail, the selective etching mold has protrusions (or protruding structures) that, upon contact with the reflective layer, remove corresponding parts thereof. Otherwise, the mold can simply be flat and, in this case, it is the micro-lenticular morphology of the underlying layer that causes the contact between mold and reflective material to be discontinuous. In this case, the etching occurs only on the top parts of the micro-lenses, and therefore the reflective layer is removed only in those areas. Still preferably, the mold is a microstructured, elastomeric mold. In case the mold has to be soaked in a supposedly aqueous corrosive solution, the mold is made of a structurable hydrogel, e.g. polyacrylamide gel.

[0045] Preferably, the used corrosive solution is based on acids and oxidizers. Still preferably, the corrosive solution is: for aluminum Al, a H3PO4:HNO3:CH3COOH:H2O mixture; for copper Cu, diluted HN03; for silver Ag, diluted HN03.

[0046] According to this second embodiment, the at least one reflective element 5 is obtained on the shaped surface 4 at the non-protruding part of the mold.

[0047] According to a third embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of placing a shadow mask on the shaped surface 4 of the first portion 3 a of the intermediate layer 3, depositing a sacrificial layer through the shadow mask, removing the shadow mask, depositing a reflective material layer on the shaped surface 4 covered by the sacrificial layer obtained from the previous step, removing the sacrificial layer and the reflective material deposited on the sacrificial layer.

[0048] Preferably, the reflective material layer is deposited by spray coating. Still preferably, the reflective material of the reflective material layer is a reflective metal or a reflective ink. As already mentioned in the foregoing, the micro-contact stamping can be used, which involves the application of a micro- structured mold, covered by a reflective material, on the shaped surface 4. Preferably, the micro-contact stamping involves the use of reflective ink.

[0049] Still preferably, the shadow mask has at least one hole having a size in the range of micrometers. Preferably, the at least one hole has a circular shape with a micrometer diameter. Preferably, the shadow mask has a plurality of holes.

[0050] In other words, according to the third embodiment, the at least one reflective element 5 appears as the mold of the shadow mask, since the reflective material of the reflective material layer is removed at the holes of the shadow mask.

[0051] According to a fourth embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of making the at least one reflective element 5 by electrospinning a reflective material, and depositing the at least one reflective element 5 on the shaped surface 4 of the first portion 3a of the intermediate layer 3.

[0052] Preferably, the at least one reflective element 5 is made with a reflective ink. Still preferably, the reflective ink comprises metal nanoparticles mixed with an electrospinnable polymer. An object of the present invention is also a transparent multi-layer screen 1 for projecting RGB images for displaying both information and / or images on the screen and what is beyond the screen. An example of multi-layer screen 1 according to the invention is a screen for head-up displays or for displaying contents in museums or on shop windows, obtained according to the method described above.

[0053] The multi-layer screen 1 comprises a transparent first layer 2 and second layer 7.

[0054] The first layer 2 has a first face 2a and a second face 2b, parallel to each other and spaced apart along a first axis Z, which is orthogonal to the first and the second face 2a, 2b of the first layer 2. The second layer 7 has a first face 7a and a second face 7b, parallel to each other and spaced apart along the first axis Z, which is orthogonal to the first and the second face 7a, 7b of the second layer 7. It should be noted that the first face 2a of the first layer 2 and the second face 7b of the second layer 7 face the surrounding environment. The second face 2b of the first layer 2 and the first face 7a of the second layer 7 face each other.

[0055] Preferably, the first and the second layer 2, 7 are plates. Preferably, the first and the second layer 2, 7 are made of glass or of polycarbonate, of polyethylene terephthalate, or of acrylic glass (polymethylmethacrylate). Preferably, the first and the second layer 2, 7 each have a thickness SI along the first axis Z ranging between 0.5 and 2.0 mm.

[0056] The multi-layer screen 1 comprises a transparent intermediate layer 3 arranged between the first and the second plate 2, 7. The intermediate layer 3 has a first face 31a at the second face 2b of the first layer 2. The intermediate layer 3 has a second face 3 lb at the first face 7a of the second layer 7. The first and the second face 31a, 31b of the intermediate layer 3 are spaced apart along the first axis Z.

[0057] Preferably, the intermediate layer 3 is made with a polymeric material. Still preferably, the intermediate layer 3 is made with a resin, such as an epoxy photo- polymerizable resin, or of a polysiloxane-based, organic / inorganic, hybrid photo- polymerizable polymer.

[0058] Preferably, the intermediate layer 3 has a thickness S2 along the first axis Z ranging between 0.5 and 2.0 mm.

[0059] Referring to the method for making the multi-layer screen 1, the intermediate layer 3 has a first and a second portion 3a, 3b of the intermediate layer. It is worth noting that, at the first portion 3 a of the intermediate layer 3, during the making of the multilayer screen 1, the first face 31 of the intermediate layer 3 and the shaped surface 4 can be identified. Further, at the second portion 3b of the intermediate layer, during the making of the multi-layer screen 1, the second face 3 lb of the intermediate layer 3 and a counter-shaped surface 32, configured to be complementary to the shaped surface 4, can be identified.

[0060] It is, therefore, apparent that in the multi-layer screen 1 the first and the second portion 3a, 3b of the intermediate layer 3 cannot be identified, since the second portion 3b of the intermediate layer 3 is configured to be complementary to the first portion 3a of the intermediate layer 3, besides being made of the same material.

[0061] The multi-layer screen 1 comprises at least one reflective element 5 in the intermediate layer 3, configured to at least partially reflect an incident light beam generated by a projector towards a user. The at least one reflective element is arranged between the first and the second face 3 la, 3 lb of the intermediate layer 3.

[0062] It is worth noting that the at least one reflective element 5 is placed at the shaped surface 4 partially covering at least one micro-lens. The micro-lenses cannot be identified in the multi-layer screen 1 due to the configuration of the first and the second portion 3a, 3b of the intermediate layer 3. In the multi-layer screen 1, the first and the second portion 3a, 3b of the intermediate layer 3 are continuous. The at least one reflective element 5 is embedded in the intermediate layer 3 and configured to be shaped like the shaped surface 4 of the first portion 3a of the intermediate layer 3. In other words, referring to Figures lb and, in particular, 1c, showing the multi-layer in section, it is possible to notice that the at least one reflective element 5, although it is characterized by a fragmented and apparently disorderly appearance, follows the profile determined by the micro-lenticular morphology, reflecting the light according to the angle of the same microlenses that it partially covers. Preferably, the at least one reflective element 5 has a concave shape. Preferably, the concavity of the at least one reflective element 5 faces towards the user observing the multi-layer screen 1.

[0063] According to an embodiment, the at least one reflective element 5 comprises a plurality of reflective elements 5 that are distinct from each other.

[0064] Preferably, referring to the accompanying Figures 2 and 6, the reflective elements 5 are disorderly arranged within the intermediate layer 3.

[0065] Preferably, referring to Figures 3 and 5, the reflective elements 5 are arranged in at least one row 6 within the intermediate layer 3. In other words, in this embodiment, the reflective elements 5 are aligned at least along a row 6. Preferably, according to an embodiment shown in Figure 3, the reflective elements 5 belonging to two consecutive rows 6 are not aligned. Preferably, according to a further embodiment not shown in the accompanying Figures, the reflective elements 5 belonging to two consecutive rows 6 are aligned.

[0066] Preferably, as shown in Figures 2 and 3, each reflective element 5 has a circular shape. In other words, each circular-shaped reflective element 5 can be arranged disorderly, or along at least one row 6, or according to an orderly grid.

[0067] Still preferably, each circular-shaped reflective element 5 has micrometer sizes, with a diameter in the range of 30-300 pm.

[0068] Preferably, as shown in Figures 5 and 6, each reflective element 5 has a band shape, a first width DI being less than a length D2. In other words, each band-shaped reflective element 5 can be arranged disorderly, or along at least one row 6.

[0069] Referring to the embodiment of Figure 5, the band reflective elements 5 are arranged in parallel rows 6. According to an embodiment not shown in the Figures, the rows 6 can also be non-parallel.

[0070] Still preferably, each band-shaped reflective element 5 has a first dimension in a range of 30-300 pm, and a second dimension D2 in a range comparable to the width of the micro-lenticular shaped layer.

[0071] According to a further embodiment, the at least one reflective element 5 comprises a single reflective layer.

[0072] Preferably, the single reflective layer has a meshed configuration, as shown in Figure 4, which therefore only partially covers the shaped surface 4.

[0073] Preferably, the single reflective layer in the meshed configuration has at least one opening 33, at which the reflective material is absent.

[0074] Still preferably, the openings 33 have, for example, a circular shape.

[0075] Still preferably, the openings 33 are arranged along at least one row 6.

[0076] Some of the possible embodiments relating to multi-layer screens 1 and to how the at least one reflective element 5 is made, will now be described for each embodiment.

[0077] Figure 2 shows a first embodiment of a multi-layer screen 1 comprising a transparent first and second layers 2, 7, a transparent intermediate layer 3 arranged between the first and the second plate 2, 7, and at least one reflective element 5.

[0078] According to the embodiment of the multi-layer screen 1 of Figure 2, the at least one reflective element 5 comprises a plurality of reflective elements that are distinct from each other.

[0079] In the embodiment of Figure 2, the reflective elements 5 have a circular shape.

[0080] Furthermore, still according to the embodiment of Figure 2, the reflective elements 5 are disorderly arranged within the intermediate layer 3. In more detail, the reflective elements 5 are arranged on the shaped surface 4 of the first portion 3a of the intermediate layer 3 so that each convexity of the shaped surface 4 is partially covered by at least one reflective element 5.

[0081] According to the embodiment of Figure 2, the step of depositing at least one reflective element 5 at the shaped surface 4 of the first portion 3a of the intermediate layer can be implemented according to different embodiments.

[0082] According to a first embodiment, the step of depositing at least one reflective element 5 comprises the sub-step of depositing a reflective element 5 which is implemented by spray coating a reflective material on the shaped surface of the first portion 3a of the intermediate layer 3. Preferably, the reflective element 5 made by spray coating is made with a reflective ink. Still preferably, the reflective ink comprises metal nanoparticles.

[0083] According to a second embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of placing a shadow mask on the shaped surface 4 of the first portion 3 a of the intermediate layer 3, depositing a reflective material on the shaped surface 4 through the shadow mask, and removing the shadow mask. Preferably, the reflective material is deposited by spray coating.

[0084] Preferably, when the reflective material layer is deposited by spray coating with or without the shadow mask, the reflective material is a reflective ink. Preferably, the reflective ink comprises metal nanoparticles.

[0085] Preferably, when the reflective material layer is deposited by vacuum evaporation, the reflective material is a reflective metal.

[0086] Figure 3 shows a second embodiment of a multi-layer screen 1 comprising a first and a second layer 2, 7, a transparent intermediate layer 3 arranged between the first and the second plate 2, 7, and at least one reflective element 5. According to the embodiment of the multi-layer screen 1 of Figure 2, the at least one reflective element 5 comprises a plurality of reflective elements that are distinct from each other.

[0087] Furthermore, still according to the second embodiment of Figure 3, the reflective elements 5 are arranged along at least one row 6 within the intermediate layer 3. In more detail, the reflective elements 5 are arranged on the shaped surface 4 of the first portion 3 a of the intermediate layer 3 so that each convexity of the shaped surface 4 is partially covered by a respective reflective element 5. Preferably, the reflective element 5 can be placed at an apical position of a respective microlens, or in an offset position and / or in an offset manner with respect to the apical position. Advantageously, it is possible to maximize the reflection of the light towards a pre-determined user’s position.

[0088] In the embodiment of Figure 3, the reflective elements 5 have a circular shape.

[0089] According to the embodiment of Figure 3, the step of depositing at least one reflective element 5 at the shaped surface 4 of the first portion 3a of the intermediate layer 3 can be implemented according to different embodiments.

[0090] According to a first embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of placing a shadow mask on the shaped surface 4 of the first portion 3 a of the intermediate layer 3, depositing a reflective material layer through the shadow mask, and removing the shadow mask.

[0091] Preferably, the sub-step of depositing a reflective material layer is implemented by spray coating a reflective material on the shaped surface 4 of the first portion 3 a of the intermediate layer 3. Preferably, the reflective element 5 made by spray coating is made with a reflective ink. Still preferably, the reflective ink comprises metal nanoparticles. Preferably, when the reflective material layer is deposited by vacuum evaporation, the reflective material is a reflective metal.

[0092] According to a second embodiment, the step of depositing at least one reflective element 5 is implemented by micro-contact stamping. Preferably, the micro-contact stamping involves the use of reflective ink. Still preferably, the reflective ink comprises metal nanoparticles. Still preferably, the micro-contact stamping involves the use of a shaped elastomeric mold covered by a reflective ink.

[0093] Figure 4 shows a third embodiment of a multi-layer screen 1 comprising a transparent first and second layers 2, 7, a transparent intermediate layer 3 arranged between the first and the second plate 2, 7, and a single reflective element 5. Preferably, the embodiment of the multi-layer screen 1 of Figure 4 comprises a single reflective layer.

[0094] According to the embodiment of the multi-layer screen 1 of Figure 4, the single reflective layer has a meshed configuration. Preferably, the reflective element 5 in the meshed configuration has at least one opening 33, at which the reflective material is absent. Still preferably, the openings 33 have, for example, a circular shape. Still preferably, the openings 33 are arranged at least along one line 6. In other words, the reflective element 5 of the third embodiment is configured like a net extending across the shaped surface 4.

[0095] The reflective element 5 is arranged so as to partially cover the micro-lenses. In other words, the reflective element 5 is arranged so as to partially cover the microlenses within the intermediate layer 3. Each micro-lens is partially covered by a portion of the reflective element 5.

[0096] According to the embodiment of Figure 4, the step of depositing the reflective element 5 at the shaped surface 4 of the first portion 3a of the intermediate layer can be implemented according to different embodiments.

[0097] According to a first embodiment, the step of depositing the reflective element 5 comprises the sub-steps of depositing a reflective material layer on the shaped surface 4 of the first portion 3 a of the intermediate layer 3, etching the reflective material layer by placing a mold soaked in a corrosive solution on the reflective material layer, removing the mold.

[0098] Preferably, the reflective material is a dielectric material or a reflective metal. Still preferably, the dielectric material is, for example, an oxide multi-layer.

[0099] Still preferably, the mold is a micro- structured, elastomeric mold.

[0100] Preferably, the mold is removed after 2-20 min. According to a second embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of: placing a shadow mask on the shaped surface 4 of the first portion 3 a of the intermediate layer 3, depositing a sacrificial layer through the shadow mask, removing the shadow mask, depositing a reflective material layer on the shaped surface 4 covered by the sacrificial layer obtained from the previous step, removing the sacrificial layer and the reflective material deposited on the sacrificial layer.

[0101] Preferably, the sacrificial layer is a water-soluble polymer, such as polyacrylic acid, polyvinyl alcohol, pedot:PSS or, as an alternative, an organic solvent-soluble polymer, such as polymethyl methacrylate or polystyrene. Still preferably, the sacrificial layer is removed by immersion and repeated washings in water if the sacrificial layer is soluble in water, or by immersion and washings in toluene or dichloromethane if the sacrificial layer is soluble in organic solvents.

[0102] Still preferably, the deposition of the reflective material is carried out by evaporation. Preferably, the reflective material is a reflective metal.

[0103] Figure 5 shows a fourth embodiment of a multi-layer screen 1 comprising a first and a second layer 2, 7, a transparent intermediate layer 3 arranged between the first and the second plate 2, 7, and at least one reflective element 5. According to the embodiment of the multi-layer screen 1 of Figure 2, the at least one reflective element 5 comprises a plurality of reflective elements that are distinct from each other.

[0104] Furthermore, still according to the second embodiment of Figure 3, each reflective element 5 has a band shape, a width DI being smaller than a length D2.

[0105] Preferably, the reflective elements 5 are arranged along at least one row 6 within the intermediate layer 3. Preferably, along each row 6 there exists at least one reflective element 5. Still preferably, each row 6 comprises a single band reflective element 5.

[0106] Referring to the embodiment of Figure 5, the band reflective elements 5 are arranged in parallel rows 6. According to an embodiment not shown in the Figures, the rows 6 can also be non-parallel.

[0107] Advantageously, by varying the second dimension D2 and / or the density of the rows 6 also within the multi-layer screen 1 itself, it is possible to maximize the reflection of the light towards a user.

[0108] According to the embodiment of Figure 5, the step of depositing at least one reflective element 5 at the shaped surface 4 of the first portion 3a of the intermediate layer 3 can be implemented according to different embodiments.

[0109] According to a first embodiment, the step of depositing at least one reflective element 5 comprises the sub-steps of placing a shadow mask on the shaped surface 4 of the first portion 3 a of the intermediate layer 3, depositing a reflective material on the shaped surface 4 through the shadow mask, and removing the shadow mask. Preferably, the reflective material is deposited by spray coating of a reflective ink, or by evaporation of a reflective metal.

[0110] According to a second embodiment, the step of depositing at least one reflective element 5 is carried out by micro-contact stamping. The micro-contact stamping involves the application of a micro- structured mold, covered by a reflective material, on the shaped surface 4. Preferably, the micro-contact stamping involves the use of reflective ink.

[0111] Figure 6 shows a fifth embodiment of a multi-layer screen 1 comprising a first and a second layer 2, 7, a transparent intermediate layer 3 arranged between the first and the second plate 2, 7, and at least one reflective element 5. According to the embodiment of the multi-layer screen 1 of Figure 2, the at least one reflective element 5 comprises a plurality of reflective elements that are distinct from each other.

[0112] Furthermore, still according to the second embodiment of Figure 5, each reflective element 5 has a band shape, a width DI being smaller than a length D2.

[0113] Preferably, the reflective elements 5 are randomly arranged on the shaped surface 4 so that each micro-lens is partially covered by at least one reflective element According to the embodiment of Figure 5, the step of depositing at least one reflective element 5 at the shaped surface 4 of the first portion 3a of the intermediate layer 3 comprises the sub-steps of making the at least one reflective element 5 by electrospinning a reflective material, and depositing the at least one reflective element 5 on the shaped surface 4 of the first portion 3a of the intermediate layer 3.

[0114] Preferably, the at least one reflective element 5 is made with a reflective ink. Still preferably, the reflective ink comprises metal nanoparticles mixed with an electrospinnable polymer. Preferably, the fiber to band transformation of the reflective element is implemented by post-deposition heat treatment (90-130°C).

[0115] It should be noted that the second dimension D2 has a size related to the electrospinning process. Preferably, the band width DI ranges from 0.5 to 10 pm. In this embodiment, the amount of reflected light is directly proportional to the number of reflective elements 5 on the shaped surface 4. Specifically, the number of reflective elements 5 deposited on the shaped surface 4 is directly proportional to the duration of the electrospinning process.

Claims

CLAIMS1. A method for making a multi-layer screen (1), comprising the steps of:- providing a transparent first layer (2),- depositing on the first layer (2) a first portion (3a) of a transparent intermediate layer (3) exhibiting a micro-lenticular shaped surface (4) defining a plurality of micro-lenses,- depositing at least one reflective element (5) at the shaped surface (4) of the first portion (3a) of the intermediate layer (3), which is configured to partially cover at least one micro-lens of the plurality of micro-lenses obtained from the previous step,- depositing a second portion (3b) of the transparent intermediate layer (3) on the shaped surface (4) of the first portion (3a) of the intermediate layer (3) partially covered by the at least one reflective element (5) obtained from the previous step,- covering the second portion (3b) of the intermediate layer (3) obtained from the previous step with a transparent second layer (7).

2. The method for making a multi-layer screen (1) of claim 1, wherein the step of depositing at least one reflective element comprises the sub-steps of:- covering the shaped surface (4) of the first portion (3a) of the intermediate layer (3) with a shadow mask,- depositing a reflective material layer on the shaped surface (4) covered by the shadow mask obtained from the previous step,- removing the shadow mask.

3. The method for making a multi-layer screen (1) of claim 1, wherein the step of depositing at least one reflective element comprises the sub-steps of:- depositing a reflective material layer on the shaped surface (4) of the first portion (3 a) of the intermediate layer (3),- etching the reflective material layer by placing a mold soaked in a corrosive solutionon the reflective material layer, - removing the mold.

4. The method for making a multi-layer screen (1) of claim 1, wherein the step of depositing at least one reflective element comprises the sub-steps of:- placing a shadow mask on the shaped surface (4) of the first portion (3a) of the intermediate layer (3),- depositing a sacrificial layer through the shadow mask,- removing the shadow mask,- depositing a reflective material layer on the shaped surface (4) covered by the sacrificial layer obtained from the previous step,- removing the sacrificial layer and the reflective material deposited on the sacrificial layer.

5. The method for making a multi-layer screen (1) of claim 1, wherein the step of depositing at least one reflective element comprises the sub-steps of:- making the at least one reflective element (5) by electrospinning a reflective material,- depositing the at least one reflective element on the shaped surface (4) of the first intermediate portion (3a).

6. A transparent multi-layer screen (1) for projecting RGB images obtained according to the method of claims 1 to 5, comprising:- a transparent first layer (2) and second layer (7),- a transparent intermediate layer (3) arranged between the first and the second layer (2, 7),- at least one reflective element (5) in the intermediate layer (3) configured to at least partially reflect an incident light beam generated by a projector.

7. The multi-layer screen (1) of claim 6, wherein the at least one reflective element (5) comprises a plurality of reflective elements that are distinct from each other.

8. The multi-layer screen (1) of claim 7, wherein the reflective elements (5) are disorderly arranged within the intermediate layer (3).

9. The multi-layer screen (1) of claim 7, wherein the reflective elements (5) are arranged in at least one row (6) within the intermediate layer (3).

10. The multi-layer screen (1) of claim 8 or 9, wherein each reflective element (5) has a circular shape.

11. The multi-layer screen (1) of claim 8 or 9, wherein each reflective element (5) has a band shape, a width (DI) of the band being less than a length (D2) of the band.

12. The multi-layer screen (1) of claim 6, wherein the at least one reflective element (5) comprises a single reflective layer.

13. The multi-layer screen (1) of claim 12, wherein the single reflective layer has a meshed configuration.

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