EP4183969A1

EP4183969A1 - Daylight management unit

Info

Publication number: EP4183969A1
Application number: EP22208352.9A
Authority: EP
Inventors: Paolo Di Trapani
Original assignee: Universita degli Studi dell Insubria; CoeLux SRL
Current assignee: CoeLux SRL
Priority date: 2021-11-19
Filing date: 2022-11-18
Publication date: 2023-05-24
Also published as: IT202100029312A1

Abstract

The present invention refers to a daylight management unit (200,200',200") comprising a plurality of lamellas (201) being arranged parallel to each other, each lamella (201) comprises a first non-planar upper face, defining an upper surface (211) comprising a portion having an upwardly facing concavity and a reflective portion (214), and a second lower face defining a lower surface (212), wherein one between the upper surface (211) and the lower surface (212) comprises a portion coated with a diffusion layer (202) configured to provide a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red.

Description

Technical field

The present invention refers in general terms to daylight management units for the interior or exterior cladding of the transparent structures of a building facade, such as windows and glazing. In particular, the present invention relates to a chromatic daylight management unit, i.e. capable of interacting with an incident light in such a way as to generate a reflected light with chromatic effects, thus offering the observer a particular visual perception of the unit itself and of the surrounding environment.

Background art

Among the daylight management units, the traditional solar shielding units or sunshade units used at the transparent structures of the facades, such as windows, French windows or glazing, to reduce the entry of light from the outside into an environment are, among other things, known. Generally speaking, the solar shielding units comprise a structure of lamellas which are arranged parallel to each other and spaced along a direction orthogonal to the development direction of the lamellas. The lamellas are generally fixedly constrained or movably connected to a support structure so as to maintain the arrangement parallel and spaced apart. The movable connection between the lamellas and the support structure is usually aimed at allowing the lamellas each to rotate around an axis of rotation parallel to their development axis. This allows an adjustment of the inclination of the lamellas with respect to the transparent structure, which can therefore be modified according to the contingent weather conditions and/or the direction of the incident sunlight. Furthermore, the movable connection between the lamellas and the support structure generally allows the lamellas to be retracted together in such a way that the surface of the transparent structure is at least partially freed and thus allows more light to enter into the environment.
Another type of known daylight management unit, particularly suitable for coating the transparent portions of the facades, comprises a lamella structure housed between a pair of thin panels that are transparent to visible light, constrained to a support structure, for example a frame, so as to be kept rigidly parallel and mutually spaced. The lamella structure is therefore housed, generally in a suspended configuration, in the gap between the two panels. These particular solar shielding units are usually used overlapping with or as a replacement of the transparent structures of the facades.
Finally, there are known daylight management units configured to allow the entry of part of the incident light, redirecting it by reflection towards the ceiling of the room. Such particular daylight management units achieve the double effect of effective shading from incident sunlight with respect to the portions of the interior environment in which people are usually located, while not losing substantial amounts of light that could penetrate into such an environment. The interior environment is therefore overall brighter than using solar shielding units.
The known daylight management units, while offering an excellent result in terms of protection and shading with respect to the sunlight incident on the facades, are not usually able to offer particular chromatic effects. In particular, the daylight management units configured to reflect part of the incident sunlight towards the interior environment tend to produce a reflected light in the interior environment which, on a clear day and excluding the short transient moments of sunrise and sunset, is cold and uncomfortable. Specifically, this reflected light, if directed on the ceiling or on a light wall in a mainly directional way, creates in the internal space the effect of a lunar type lighting or, that is, characterized by the presence of surfaces illuminated by cold light and dark shadows without colour, or, if directed on the ceiling or on a light wall in a mainly diffused way, the effect of a grey and cloudy sky. The internal lighting generated by this cold light also appears unnatural as it lacks the component of diffused light blue light coming from the sky, which in the outdoor in the case of a clear day illuminates and colours the shadows light blue. In fact, this component is substantially shielded by the known units, failing to reach the interior environment. Last but not least, the appearance of the known daylight management units does not undergo substantial variations between the condition in which the unit is irradiated by sunlight and the condition in which the unit is not irradiated. Such daylight management units appear in fact always substantially dark, eliminating from the window the typical brightness of an opening towards the sky and offering instead the image of a window or portion of a closed window, that is obscured by blinds, shutters or the like.
The Applicant has therefore strongly perceived the need to realize a daylight management unit that is able both to give a chromatic effect to the reflected light towards the interior environment, in particular making the reflected light warmer and more pleasant, and to recreate inside the environment a lighting condition similar to that which would occur in the absence of the solar shielding unit, that is, comprising a blue diffused light component similar to that which the diffused light from the sky, penetrating through the transparent structures would produce. In this way, the daylight management unit has the same appearance as a window that is not obscured, through which it is possible to see the sky on a clear sunny day.
The Applicant also considered devising a daylight management unit that, under certain conditions, could take on a different chromatic appearance, offering an observer an aesthetic effect of the unit itself of particular pleasure.

Summary of the invention

In a first aspect, the present invention is directed to a daylight management unit comprising a plurality of lamellas, each having an elongated development along a respective development axis C of lamella. Each lamella has two opposing faces having a much more pronounced extension along a first direction parallel to the development axis C and a section orthogonal to the development axis C that is substantially constant and having a barycentre B, the set of the barycentres B of the sections defining a barycentre axis. The lamellas are arranged parallel to each other with the barycentre axes comprised in the same plane of the axes and spaced apart along a distancing direction comprised in the plane of the axes and orthogonal to the barycentre axes B. There is further provided a structure of support of the lamellas configured to support the plurality of lamellas in the condition of parallel lamellas.
In the configuration of use of the unit, each lamella of the plurality of lamellas comprises a first non-planar upper face, defining an upper surface comprising at least a portion having, with reference to a section plane orthogonal to the development axis C, an upwardly facing concavity and at least one reflective portion, and a second lower face defining a lower surface.
According to the present invention, at least one between the upper surface and the lower surface comprises at least a portion coated with a diffusion layer configured to provide a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red, wherein the diffusion layer comprises a plurality of diffusion nanometric elements made of a first material having a first refractive index n₁,n_p, immersed in a second material having a second refractive index n₂,n_h other than the first n₁,n_p, wherein a ratio (e.g. $m \equiv \frac{n_{p}}{n_{h}}$
) between the first n₁,n_p and the second n₂,n_h refractive index, a number N of nanometric elements per area unit and an average size of the nanometric elements of the plurality of diffusion nanometric elements referred to a diameter of the smallest cylinder d_c that circumscribes them are selected to preferentially diffuse components of incident light at a small wavelength with respect to components of incident light at a large wavelength and to preferentially transmit components of incident light at a large wavelength with respect to components of incident light at a small wavelength.
By "range of the red" it is meant a range of wavelengths comprised between 600 nm and 740 nm.
By "range of the yellow" it is meant a range of wavelengths comprised between 530 nm and 600 nm.
By "blue range" it is meant in a broad sense a range of wavelengths comprised between 380 nm and 500 nm, thus also comprising also the wavelengths that conventionally range from violet to cyan.
Advantageously, the particular configuration of the lamellas makes it possible to effectively redirect the daylight incident on the daylight management unit upwards of the interior environment delimited by this unit, with reference to the entire range of directions and angles of incidence of sunlight as a function of the time of day and the period of the year, normally comprised between 10° and 80°. It is in fact to be considered that the direct solar radiation hits from altitudes and azimuthal angles that constantly vary depending on both the time of day and the period of year, while the diffuse radiation emitted from the sky comes from all visible areas of the celestial vault. In addition, the particular reflection behaviour given by at least part of the surface of the lamellas allows to recreate the component of blue diffused light capable of imitating the soft lighting effect generated by the sky within an environment. In this way, the shaded areas that are not illuminated by the direct light reflected by regular reflection by the lamellas are tinted light blue due to the effect of the diffused light reflected by reflection diffused by the same lamellas, as would happen in the absence of sun shielding.
The particular reflection behaviour given by at least part of the surface of the lamellas also confers a characteristic aesthetic appearance to the side of the lamellas inside the environment delimited by the daylight management unit, when the lamellas are struck by a collimated beam of incident light, where collimated beam means a beam of light having a main propagation direction and an angular divergence around this propagation direction less than 45°, preferably less than 10°, even more preferably less than 2°. Specifically, a light blue diffused light is generated, directed internally to the environment, which makes the lamellas appear luminous and light bluish, when observed from the interior environment, producing an image similar to the image of the clear sky.
The unit according to the present invention can comprise one or more of the following additional features, which can also be combined together at will in order to satisfy specific requirements defined by a corresponding application purpose.
In a variant of the invention, the at least one upper surface portion having upwardly facing concavity is the reflective upper surface portion.
In a variant of the invention, the lower surface comprises at least one reflective portion configured to cooperate with the at least one reflective portion of the upper surface of an adjacent lamella placed below, so as to redirect upward incident rays on the reflective portion of the upper surface of the adjacent lamella.
Preferably, the at least one portion coated with a diffusion layer is the at least one reflective portion of the lower surface.
Preferably, the at least one reflective portion of the lower surface of each lamella is arranged at or near an entry side end of the lamella, with reference to a section orthogonal to the development axis C wherein the lamellas have two opposite side ends, and wherein the at least one reflective portion of the upper surface of each lamella is placed at an entry side end, opposite the exit end.
In the context of the present invention and the appended claims, "entry end" means the end from the side configured to accept sunlight coming from the outside, i.e. the side configured to accept a wide variation of directions of acceptance of the incident light, while "exit end" means the end from the side configured to direct the reflected light upwards, specifically towards the ceiling, i.e. according to a smaller amplitude of exit directions than the amplitude of the directions of acceptance.
In this way it is thus ensured that the rays of light that manage to pass from the side of irradiation to the opposite side of the daylight management unit have undergone at least one reflection on the reflective portion of the lower surface of a lamella, thus giving rise to a reflection that is differentiated as a function of the wavelength of the light and thus generating the bluish diffuse light that confers on the lamellas, seen from within the environment delimited by the daylight management unit, the brightness and light bluish colouring that the invention wants to obtain.
Preferably, the at least one reflective portion of the lower surface of each lamella has a flat shape or has a downwardly facing concavity in use.
Advantageously, this makes it possible to cooperate with the reflective portion, possibly with an upwardly facing concavity, of the upper surface of an underlying lamella in order to redirect the rays reflected from it upwards.
In a variant of the invention, the at least one portion coated with a diffusion layer comprises at least one of the following features:

is arranged on the at least one between the upper surface and the lower surface in such a way as to intercept at least 50%, preferably 70%, more preferably 90% of the regularly reflected rays exiting the unit in the case of incident rays having a direction that form an angle of incidence α with a horizontal plane, the angle of incidence α being comprised between 40°-50°, preferably between 30°-60°, more preferably between 20°-70°;
extends over at least 10%, preferably over at least 20%, more preferably over at least 30% of the upper and lower surfaces of the lamella; and
is arranged at or near an entry side end of the lamella with reference to a section orthogonal to the development axis C in which the lamellas have two opposite side ends.

Preferably, at least one between the first and second materials exhibit a greater absorption for wavelengths of the incident light comprised in the range of the red and of the yellow than wavelengths of the incident light comprised in the range of the blue.
In one variant of the invention, the at least one portion coated with a diffusion layer is covered or protected by a layer of transparent material, such as a paint or a polymer film.
Preferably, the diffusion nanometric elements of the diffusion layer are substantially transparent or substantially non-absorbent at least with respect to electromagnetic radiations with wavelength comprised in the visible light spectrum, have an average size comprised between 5 nm and 350 nm, preferably between 10 nm-250 nm, more preferably between 40 nm-180 nm, even more preferably between 60 nm-150 nm, and a first refractive index n₁,n_p and are immersed in a substantially transparent or substantially non-absorbent host material at least with respect to electromagnetic radiation with wavelength comprised in the visible light spectrum and having a second refractive index n₂,n_h, such that the ratio among refractive indices $m \equiv \frac{n_{p}}{n_{h}}$
is comprised in the range 0.5≤m≤2.5, for example 0.7≤m≤2.1 or 0.7≤m≤1.9.
Alternatively or in addition, the diffusion nanometric elements of the diffusion layer are present in the diffusion layer in a number N per unit area as a function of an effective diameter of element or particle D = dc nh (D indicated in [metres]), dc being the diameter of the smallest cylinder that on average circumscribes said nanometric elements, which falls within the range defined by $N \geq N_{\min} = \frac{3.47 \times 10^{- 29}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [{metres}^{- 2}]$
, and $N \leq N_{\max} = \frac{1.03 \times 10^{- 27}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [{metres}^{- 2}]$
.
In a variant of the invention, the diffusion nanometric elements of the diffusion layer are selected from the group consisting of:

nanometric elements in solid phase,
nanometric elements in liquid phase,
nanometric elements in gas phase,
three-dimensional metal oxides
nano-pores
nano-channels, and
nano-pillars.

In one variant of the invention, the first material is a metal oxide, preferably aluminium oxide (alumina), titanium oxide (titania) or zinc oxide.
In a variant of the invention, the second material is air or is selected from a polymer, a resin, a silicone, a different oxide, said second material being at least partially non-absorbent, or transparent at least to electromagnetic radiations with wavelength comprised in the visible light spectrum and having a second refractive index n₂ comprised between 1.3 and 1.55, preferably between 1.49 and 1.52.
In a variant of the invention, the second material is a soluble fluoropolymer-based resin, preferably a polyurethane resin with a high fluorocarbon content, more preferably a soluble fluoropolymer-based resin with second refractive index n₂ comprised between 1.45 and 1.50, even more preferably with second refractive index n₂ equal to 1.48.
In a variant of the invention, at least the portion coated with a diffusion layer is configured to satisfy at least one thereof:

not to absorb substantially light in the visible range; and/or
to diffuse light at a wavelength of 450 nm at least 1.2 times, preferably at least 1.4 times, more preferably 1.6 times more efficiently than the light at a wavelength of about 630 nm, i.e. to have a diffused reflectance at a wavelength of 450 nm at least 1.2 times, preferably at least 1.4 times, more preferably at least 1.6 times greater than the diffused reflectance at 630 nm, and/or to regularly reflect light at a wavelength of 630 nm at least 1.05 times, preferably at least 1.2 times, more preferably 1.6 times, more efficiently than the light at a wavelength of about 450 nm, i.e. to have a regular reflectance at a wavelength of 630 nm at least 1.05 times, preferably at least 1.2 times, more preferably at least 1.6 times greater than the regular reflectance at 450 nm; and/or
to generate a regularly reflected beam having chromatic coordinates comprised in a region of the colour plane CIE 1976 u'-v' with coordinates u' > 0.210 and v' > 0.470 and a maximum Cartesian distance in this colour plane of less than 0.1 from the Planck curve referred to the light source illuminating the daylight management unit, where said light source is a standard illuminator CIE E, and a diffused reflected beam having chromatic coordinates comprised in a region of the colour plane with coordinates u'<0.210 and v' <0.430, as illuminated by a standard illuminator CIE E; and/or
to have a greater absorption for wavelengths of the incident light comprised in the range of the red and of the yellow than wavelengths of the incident light comprised in the range of the blue.

In a variant of the invention, the reflective portion of the lower surface of the lamella and the reflective portion of the upper surface of the lamella each comprise at least one tangent point such that the tangents to the surfaces in the section plane orthogonal to the development axis C and at the respective tangent points form a smaller angle γ of at least 10°, preferably of at least 20° more preferably of at least 40°.
In the context of the present description and in the appended claims, the term "smaller angle" referred to two straight lines that intersect in a plane means the angle less than or at most or equal to 90° that is formed between the two straight lines.
In this way it is ensured that the sunrays incident on each lamella, usually having an inclination comprised between 10° and 80° with respect to a direction parallel to a horizontal plane as a function of the time of day and the period of the year, are redirected by the reflections on the upper surfaces of an underlying and lower lamella of a lamella placed above according to a direction at most comprised in a horizontal plane or, preferably, directed upwards i.e. towards the ceiling.
In a variant of the invention, the lower surface of each lamella comprises a shielding portion adjacent to the reflective portion of the lamella and extending towards the entry side end of the lamella opposite the exit end, the shielding portion being configured to block the passage of light from one side to the other of the unit in the absence of reflections on the lamellas.
In a variant of the invention, the upper surface comprises at least a pair of adjacent planar portions inclined to each other so as to define above, in the section plane orthogonal to the development axis C, an angle β of less than 180°.
This ensures that the concavity of the lamellas is facing upwards, thus leading to redirecting the incoming light by multiple reflection upwards of the interior environment.
In a variant of the invention, the lamellas of the plurality of lamellas are constrained to the support structure each rotatably about an axis of rotation parallel or coincident to their barycentre axis B between a first and a second end position, the first and the second end position being chosen in such a way that the portion of the reflective upper surface remains with its concavity facing upwards in all the operating positions that can be assumed by the lamellas between the first and the second end position.
In one variant of the invention, the support structure comprises at least one pair of vertical uprights to which the lamellas of the plurality of lamellas are fixedly or rotatably constrained, each around an axis of rotation parallel or coincident with its barycentre axis B.
Alternatively, the support structure comprises a plurality of suspension ties connected to an upper support bar, the plurality of lamellas being tied to the suspension ties so as to be rotatable each about an axis of rotation parallel or coincident with its barycentre axis B.
Preferably, the support structure is housed in a hollow housing chamber defined between a pair of panels that are at least partially transparent to visible light.

Brief Description of the Drawings

The accompanying drawings, which are incorporated herein and form part of the description, illustrate exemplary embodiments of the present invention and, together with the description, are intended to illustrate the principles of the present invention.
In the drawings:

Fig. 1 is a schematic perspective view of a first embodiment of a daylight management unit according to the present invention;
Fig. 2 is a cross-sectional view of a pair of lamellas employed in the embodiment of the daylight management unit of Figure 1;
Fig. 3 is a cross-sectional view of a pair of lamellas employed in an alternative embodiment of the daylight management unit according to the invention;
Figs. 4a and 4b are cut-away perspective views of two variants of lamellas employed in alternative embodiments of the daylight management unit according to the present invention;
Fig. 5 is an exploded schematic perspective view of a second embodiment of a daylight management unit according to the present invention;
Fig. 6 is a schematic perspective view of a third embodiment of a daylight management unit according to the present invention;
Fig. 7 is a cross-sectional view of a pair of lamellas employed in the embodiment of the daylight management unit of Figure 6;
Figs. 8 and 9 are cut-away perspective views of two variants of lamellas of the type used in the third embodiment of the daylight management unit according to the present invention;
Figs. 10a and 10b are cross-sectional views of pairs of lamellas that differ from each other in the shape of the lower surface;
Fig. 11 is a schematic representation of the reflection effects offered by the daylight management unit according to the first embodiment of the present invention;
Figs. 12 and 13 are schematic representations of the reflection effects offered by the daylight management units according to the first embodiment of the present invention with respect to a plurality of inclinations of the lamellas and of the incident sunlight;
Fig. 14 is a schematic representation of the appearance of a daylight management unit according to the first embodiment of the present invention, perceived by an observer staying on an internal side or on an external side of the unit itself;
Fig. 15 is a schematic representation of the reflection effects offered by the daylight management unit according to the third embodiment of the present invention;
Fig. 16 is a schematic representation of the reflection effects offered by the daylight management unit according to the third embodiment of the present invention with respect to a plurality of inclinations of the incident sunlight; and
Fig. 17 is a schematic representation of the appearance of a daylight management unit according to the third embodiment of the present invention, perceived by an observer staying on an internal side or on an external side of the unit itself.

Detailed description

The following is a detailed description of exemplary embodiments of the present invention. The exemplary embodiments described herein and illustrated in the drawings are intended to convey the principles of the present invention, allowing the person skilled in the art to implement and use the present invention in numerous different situations and applications. Therefore, the exemplary embodiments are not intended, nor should they be considered, to limit the scope of patent protection. Rather, the scope of patent protection is defined by the attached claims.
For the illustration of the drawings, use is made in the following description of identical numerals or symbols to indicate construction elements with the same function. Moreover, for clarity of illustration, certain references may not be repeated in all drawings.
The use of "for example", "etc.", "or" indicates non-exclusive alternatives without limitation, unless otherwise indicated. The use of "comprises" and "includes" means "comprises or includes, but not limited to", unless otherwise indicated.
Furthermore, the use of measurements, values, shapes and geometric references (such as perpendicular and parallel) associated with terms such as "about", "almost", "substantially" or the like, is to be understood as "unless there are measurement errors" or "unless there are inaccuracies due to manufacturing tolerances" and in any case "unless there is a slight divergence with respect to the values, measurements, shapes or geometric references" to which the term is associated.
Finally, terms such as "first", "second", "upper", "lower", "main" and "secondary" are generally used to distinguish components belonging to the same type, not necessarily implying an order or priority of relationship or position.
With reference to Fig. 1 there is schematically illustrated a daylight management unit according to a first embodiment of the present invention - hereinafter for brevity also simply 'unit' - as a whole indicated with 200 in Fig. 1. The unit 200 of Fig. 1 is of the so-called "sunshade" type. The unit 200 comprises a plurality of lamellas 201 each having an elongated development along a respective development axis C of the lamella. The lamellas 201 therefore have two opposing faces surrounded by thin perimeter walls, in the order of millimetre or submillimetre, i.e. having a much more pronounced extension along a first development direction parallel to the axis C, with respect to a second development direction of these walls, and head walls orthogonal to the axis C. In particular, the lamellas 201 have a section orthogonal to the development axis C that is substantially constant having a barycentre B and the set of barycentres B of the sections defines a barycentre axis. The lamellas 201 are arranged parallel to each other, so that their barycentre axes B are all comprised in the same plane of the axes, and spaced apart along a direction comprised in the plane of the axes and orthogonal to the barycentre axes B. In particular, each lamella 201 is spaced from the adjacent lamellas by a distance d, measured in the plane of the barycentre axes B as the distance between the respective barycentre axes B. With the unit installed for use, the lamellas 201 are supported with their barycentre axes B orthogonal to a vertical plane so that the plane of the axes comprising them is a vertical plane; the direction along which the lamellas are spaced from each other is, specifically, the vertical direction (i.e. perpendicular to the ground).
In particular, in the embodiment of Fig. 1, the lamellas are constrained to a support structure 220 comprising at least one pair of vertical uprights 222. The lamellas 201 are pivoted to the uprights 222 so as to be able to rotate each around an axis of rotation parallel or coincident to the respective barycentre axis B between a first and a second end position, being able to assume any operating position comprised in the angular range between the first and the second end position. To control the rotation of the lamellas 201, in the embodiment of Fig. 1 the support structure 220 comprises two control rods 221 that are movable along the direction orthogonal to the axes B and fixedly connected to a free side of the lamellas 201 to drag them into vertical translation, thereby determining the inclination of the lamellas 201 each around its own axis of rotation.
The lamellas 201 employed in the daylight management unit 200 according to the present invention comprise a first non-planar upper face, defining an upper surface 211 comprising at least a portion having, with reference to a section plane orthogonal to the barycentre axis B, an upwardly facing concavity in at least a plurality of operating positions that can be assumed by the lamellas, when the unit 200 is in the configuration of use and at least one reflective portion. In particular, in the present case the reflective portion coincides with the portion with upwardly facing concavity.
Preferably, the lamellas 201 comprise a first non-planar upper face defining a reflective upper surface 211 having at least one portion with upwardly facing concavity in all operating positions that can be assumed by the lamellas when the unit 200 is in configuration of use. In the context of the present disclosure and in the appended claims, "upwardly facing concavity" means both an upper surface with a curved profile with at least one portion having an upwardly facing concavity curvature, and an upper surface comprising planar portions, wherein at least one pair of adjacent planar portions comprises portions that are inclined to each other so as to define above an angle β of less than 180°.
By "reflective" surface portion it is meant a surface portion configured to regularly reflect an incident light beam comprising one or more electromagnetic radiations having wavelengths comprised at least in the visible spectrum (i.e., 380 nm ≤ λ ≤ 740 nm). For example, the reflective surface or face has a regular reflectance of at least 30%, preferably of at least 50%, more preferably of at least 70% is made of a metallic material, such as aluminium (Al), titanium (Ti), silver (Ag), zinc (Zn), etc. or an alloy, such as stainless steel, comprising such materials. Eventually, the reflective surface or face may be subjected to a polishing process (mechanical or chemical). The reflected light beam may have a light intensity profile with an angular opening equal to or slightly greater than the angular opening of the light intensity profile of the incident light beam as a function of the characteristics of the reflective surface or face.
The lamellas 201 employed in the daylight management unit 200 according to the present invention further each comprise a second lower face defining a lower surface 212. The lower surface preferably comprises at least one reflective portion 213, in particular arranged at an exit side end 201a of the lamella, with reference to a section orthogonal to the development direction C in which the lamellas have two opposite side ends 201a,201b.
There is further provided a shielding portion 215 adjacent the reflective portion 213 and extending towards an entry side end 201b of the lamella, opposite the exit end 201a. The shielding portion is preferably configured to block the direct passage of sunrays towards the inside of the environment without undergoing reflections, in particular for low angles of incidence of the incident light. The daylight management unit 200 is in fact in particular configured to be mounted within an environment with the entry side end 201b arranged proximal to a transparent structure of a building, for example the glass of a window, and the exit side end 201a arranged distal from the transparent structure. Generally speaking, the daylight management unit 200 is configured to be mounted at or near a transparent structure of a building with the entry side end 201b facing the natural light source, i.e., outward with respect to the environment delimited by the transparent structure.
In particular, with reference to the section plane orthogonal to the development direction C and with the same width of the lamella measured as a tip-to-tip distance in the orthogonal section plane, the shielding portion 215 and the reflective portion 213 form an internal angle θ that is the smaller the greater the distance d between adjacent lamellas 201 is. In particular, for high distances d, the lower surface 212 assumes a more pointed shape (shown by way of example in Fig. 10a), given for example by an acute angle that is formed internally between the reflective portion 213 and the shielding portion 215. Conversely, for reduced distances d, the lower surface 212 assumes a more flattened shape (shown by way of example in Fig. 10b), given for example by an obtuse angle that is formed internally between the reflective portion 213 and the shielding portion 215. These shapes are chosen so as to prevent the entry of rays for low angles of incidence of light (for example of about 10° or less).
A reflective portion 214 of the upper surface 211 preferably placed at the entry side end 201b, opposite the exit end 201a, is also identifiable. The reflective portion 213 of the lower surface 212 and the reflective portion 214 of the upper surface 211 placed at the entry side end 201b are configured to redirect upwards by multiple reflection the rays incident on the portion 214 of the upper surface 211, for at least one operating position among the operating positions that can be assumed by the lamellas 201.
In the context of the present description and in the appended claims, by "redirecting upwards" it is meant the reflection effect, preferably multiple reflection, of at least part of the rays of light that are incident on a lamella, along directions forming an angle greater than or equal to 0° with a horizontal plane (i.e. parallel to the ground) passing through the point of last reflection with reference to multiple reflections.
By way of example, the reflective portion 213 of the lower surface 212 and the reflective portion 214 of the upper surface 211 comprise each at least one section or a tangent point such that the tangents to the surfaces in the section plane orthogonal to the development axis C and in the respective sections or tangent points form a smaller angle γ of at least 10°, preferably of at least 20°, more preferably of at least 40°. This relationship applies both to adjacent lamellas - making the reflective portion 213 of a lamella placed above interact with the reflective portion 214 of the upper surface 211 of an underlying lamella in such a way as to redirect upwards by multiple reflection the rays incident on the underlying lamella - and with reference to the surface portions 213 and 214 of the same lamella, all the lamellas 201 being shaped in the same way and constrained to the support structure 220 according to the same orientation and distancing.
According to the present invention, at least part of the upper 211 and/or lower 212 surface of the lamellas 201 - in particular at least part of the reflective portion 213 of the lower surface 212 of the lamellas - exhibits a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red.
In the context of this description and in the subsequent claims, the terms "regular reflectance" and "diffused reflectance" refer to the definitions provided in the E284 standard relating to the terminology describing the appearance of materials and light sources (ASTM E284 -09a, Standard Terminology of Appearance, ASTM International, West Conshohocken, PA, 2009). Furthermore, the term "spectral" refers to the regular reflectance and diffused reflectance evaluated as a function of the wavelengths of the light.
Consequently, when a light beam strikes the lamella 201, the electromagnetic radiations with wavelengths comprised in the blue (380 nm ≤ λ ≤ 500 nm) of the light beam preferentially undergo a diffusion - also referred to as scattering - with respect to the wavelengths comprised in the range of the red (600 nm ≤ λ ≤ 720 nm). For example, the lamella 201 does not substantially absorb light in the visible range and diffuses light at a wavelength of 450 nm (blue) at least 1.2 times, for example at least 1.4 times, as well as at least 1.6 times more efficiently than the light at the wavelength of about 630 nm (red). In other words, at a wavelength of 450 nm (blue) the diffused reflectance of the lamella 201 is at least 1.2 times, for example at least 1.4 times, as well as at least 1.6 times greater than the diffused reflectance at 630 nm (red). Similarly, the lamella 201 regularly reflects light at a wavelength of 630 nm (red) at least 1.05 times, for example at least 1.2 times, as well as at least 1.6 times, more efficiently than the light at a wavelength of about 450 nm (blue). In other words, at a wavelength of 630 nm (red) the regular reflectance of the lamella 201 is at least 1.05 times, for example at least 1.2 times, as well as at least 1.6 times greater than the reflectance regular at 450 nm (blue).
This results in that, due to the effect of the diffused reflection, the lamella 201 assumes a substantially light bluish colour when struck by a substantially directional (collimated) light beam of white light - for example a beam of white light having a divergence of less than 45°, preferably less than 10°, even more preferably less than 2° (for example, solar radiation) - that affects the surface of the lamella from a direction which forms an angle α with a horizontal plane (in the plane of orthogonal section). The light bluish colouring of the lamella 201 is observable from any direction substantially other than the specular direction with respect to the illumination direction, i.e. from a direction for which the observer does not see the specular reflection of the source, for example from a direction forming an angle with the specular direction with respect to the direction of the incident beam greater than the semi-divergence of said incident light beam. At the same time, when struck by a directional light beam of white light, the lamella 201 assumes a warm colour, for example a yellow, orange or reddish colour, if observed in the specular direction with respect to the illumination direction, i.e. from a direction for which the observer sees the specular reflection of the incident light.
Specifically, the Applicant has characterised the aesthetic effect obtained, finding that this effect is characterised by:

a regularly reflected beam having chromatic coordinates comprised in a region of the colour plane CIE 1976 u'-v' with coordinates u' > 0.210 and v' > 0.470 and a maximum Cartesian distance in this colour plane less than 0.1 from the Planck curve referred to the light source illuminating the daylight management unit, where such light source is a standard CIE E illuminator; and
a diffused reflected beam having chromatic coordinates comprised in a region of the colour plane with coordinates u'<0.210 and v'<0.430.

The regular and diffused reflections described above and/or the chromatic coordinates indicated above are obtained, for example, when at least part of the lower surface 212 of the lamellas 201 - in particular at least part of the substantially planar reflective portion 213 of the lower surface 212 of the lamellas - is coated with a diffusion layer 202 comprising a dispersion of a plurality of diffusion nanometric elements configured to preferentially diffuse components of incident light at a small wavelength with respect to components of incident light at a large wavelength, thereby implementing a diffusion of the incident light in Rayleigh-like regime or chromatic diffusion.
In the specific case of the embodiment of Fig. 2, the lamellas 201 comprise in section two linear sections, inclined to each other in such a way as to define above an angle β less than 180°, preferably less than 160° and greater than 90°, more preferably less than 150° and greater than 120°.
In an alternative embodiment - referred to in Fig. 3 only the lamellas 201 are illustrated - such lamellas comprise in section a plurality of linear sections. The sections placed at the side ends 201a 201b are inclined to each other in such a way that at least one pair of adjacent sections defines above an angle β less than 180°, preferably less than 160° and greater than 90°, more preferably less than 150° and greater than 120°.
The diffusion layer in Rayleigh-like regime or chromatic diffusion layer is a layer that covers at least a portion of the upper surface and/or of the lower surface of the lamellas and comprises a random distribution of nanoelements (nanoparticles, nanochannels, nanopillars, etc.) of a first material into a second material of different refractive index, where by random distribution it is meant a disordered distribution, that is, without order over large distances with respect to the sizes of the nanoelements.
In the lamellas illustrated in Fig. 2 and Fig. 3 the diffusion layer in Rayleigh-like regime or chromatic diffusion layer is a layer covering the entire surface of the lamella (not illustrated). This layer can be obtained, for example, through anodizing processes in the case of a lamella made of metallic material. Such layers typically comprise inclusions in gas phase (nanovacuums/nanopores) in a solid matrix, such as for example aerogels that are commonly formed by metal oxides, such as silica, alumina, iron oxide that form a solid structure that houses pores (air/gas inclusions) for example channel-shaped, or forms pillars with nanometric sizes in terms of pore/pillar diameter. By way of further example, such a layer can be obtained by surface treatments of lamellas having a surface made of or coated with organic polymers (e.g. polyacrylates, polystyrene, polyurethanes and epoxy) treated so as to form a solid structure that houses pores (air/gas inclusions) or forms pillars with nanometric sizes in terms of pore/pillar diameter.
Alternatively, as shown in Figs. 4a and 4b, the diffusion layer in Rayleigh-like regime or chromatic diffusion layer 202 is a layer applied to at least a portion of the lower surface 212 of the lamella, possibly in addition to other portions of the lamella surface. In the case of an applied layer, the Diffusion layer in Rayleigh-like regime 202 is preferably made of a material loaded with substantially transparent or substantially non-absorbent nanoparticles at least with respect to electromagnetic radiations with wavelength comprised in the visible light spectrum, having an average size comprised between 5 nm and 350 nm, preferably between 10 nm-250 nm, more preferably between 40 nm-180 nm, even more preferably between 60 nm-150 nm, referred to a diameter of the smallest cylinder d_c that circumscribes them. The nanoparticles have a first refractive index (indifferently indicated by n₁ or n_p) and are immersed in a substantially transparent or substantially non-absorbent host material at least with respect to electromagnetic radiations with wavelength comprised in the visible light spectrum and having a second refractive index (indifferently indicated by n₂ or n_h), such that a ratio between the refractive indices $m \equiv \frac{n_{p}}{n_{h}}$
is comprised in the range 0.5≤m≤2.5, for example 0.7≤m≤2.1 or 0.7≤m≤1.9.
Considering that the diffusion effects are consequential, among other things, to the ratio of refractive indices between nanoparticles and host material, the nanoparticles may be either solid particles, or optically equivalent nanometric elements in liquid or gas phase, such as generally liquid or gas-phase inclusions (e.g., nano-droplets, nanovacuums, nano-inclusions, nanobubbles, etc.), i.e., elements that have nanometric sizes and are incorporated into the host material.
Furthermore, the number N of nanoparticles acting as diffusers in Rayleigh-like regime or in chromatic diffusion regime, defined per unit area of the chromatic diffusion layer and as a function of an effective particle diameter D = d_c nh, preferably falls within the range defined by $N \geq N_{\min} = \frac{3.47 \times 10^{- 29}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
, (D indicated in [metres]) and N ≤ $N_{\max} = \frac{1.03 \times 10^{- 27}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
; for example, for embodiments that want to simulate the presence of a clear sky, N ≥ $N_{\min} = \frac{3.47 \times 10^{- 29}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
, (D indicated in [metres]) and N ≤ $N_{\max} = \frac{4.05 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
such as $N \geq N_{\min} = \frac{5.65 \times 10^{- 29}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
and $N \leq N_{\max} = \frac{3.46 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
, more specifically $N \geq N_{\min} = \frac{7.13 \times 10^{- 29}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2}$
[metres-2] and $N \leq N_{\max} = \frac{3.13 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
; and for example, for embodiments that want to simulate a Northern sky, N ≥ $N_{\min} = \frac{4.05 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
, (D indicated in [metres]) and N ≤ $N_{\max} = \frac{1.03 \times 10^{- 27}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
such as $N \geq N_{\min} = \frac{4.05 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
and $N \leq N_{\max} = \frac{7.71 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
, more specifically $N \geq N_{\min} = \frac{4.05 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2}$
[metres-2] and $N \leq N_{\max} = \frac{6.37 \times 10^{- 28}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [metres - 2]$
.
Otherwise, in the case of metal oxides or polymeric structures, the diffusion layer in Rayleigh-like regime 202 comprises a nano-pillar or nano-pore structure in a first material having a first refractive index n₁, immersed in a second material having a second refractive index n₂ other than the first, wherein the difference between the refractive indices and the nano-pillar or nano-pore structure are configured to provide a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red. For example, the first material constituting the nano-pore structure is metal oxide, preferably aluminium oxide, or alumina (Al2O3), preferably anodic aluminium oxide or AAO (acronym for the expression `Anodic Aluminium Oxide'), titanium oxide (titania) or zinc oxide and the second material is for example air, or it is selected from a transparent or at least partially non-absorbent polymer, a resin, a silicone or a different oxide (for example deposited by sol-gel) with respect to electromagnetic radiations with wavelength comprised in the visible light spectrum and having a second refractive index n₂ comprised between 1.3 and 1.55, preferably between 1.49 and 1.52, for example polyvinylchloride (PVC), polymethylmethacrylate (PMMA), polyfluorides (such as PVDF) or transparent polyacrylates. According to a preferred embodiment, the second material is a soluble fluoropolymer-based resin, preferably a polyurethane resin with a high fluorocarbon content, more preferably a soluble fluoropolymer-based resin with second refractive index n₂ comprised between 1.45 and 1.50, even more preferably with second refractive index n₂ equal to 1.48. A coating layer of this type is described in detail in International Patent Application No. PCT/IB2021/053151 filed on 16 April 2021 in the name of the same Applicant and herein fully recalled.
The diffusion layer in Rayleigh-like regime 202 comprising a nano-pillar or nano-pore structure may determine, in addition to the effect of chromatic variability as a function of the wavelength of the incident light described above, also a chromatic variability - i.e. a dependence of the regular reflectance and/or on the diffused reflectance - dependent on the direction of illumination or incidence. In other words, the colour for which an observer sees the lamella 201 from a direction of observation in proximity to the direction of specular reflection, and possibly, but not necessarily, also the colour for which an observer sees the lamella 201 from a direction of observation far from the direction of specular reflection, depends on the angle of incidence of the incident light beam on the reflective portions of the lamella 201. In the case of lamellas with variable chromatic diffusion, a variation in the colouring assumed by the lamellas is in fact perceptible as a function of their inclination, as well as of the regularly reflected beam. The colouring of the lamellas, instead of remaining substantially light blue-coloured, varies in colour as a function of the specific angle of incidence of the light on the reflective portions of the lamellas, showing shades ranging from light blue to grey. Furthermore, as a function of the same angle of incidence, the regularly reflected beam of light varies in colour between shades of yellow and shades of red.
In particularly advantageous embodiments, the upper surface 211 of the lamella 201 is also at least partially coated with a diffusion layer in Rayleigh-like regime or chromatic diffusion layer 202, as shown in Fig. 4b. In particular, the upper surface 211 of the lamella 201 is coated with a chromatic diffusion layer 202 at least at the reflective portion 214 of the upper surface 211 preferably placed at the entry side end 201b of the lamella 201, opposite the exit end 201a.
With reference to Fig. 5 there is schematically illustrated a second embodiment of a daylight management unit 200' according to the present invention. The unit 200' of Fig. 5 is of the type called "Venetian-like". The unit 200' of Fig. 5 comprises a plurality of lamellas 201 each having an elongated development along a respective development axis C of the lamella. The lamellas 201 have a section orthogonal to the development axis C that is substantially constant having a barycentre B and the set of barycentres B of the sections defines a barycentre axis. The lamellas 201 are arranged parallel to each other, with the barycentre axes comprised in a plane of the axes and spaced apart along a direction comprised in the plane of the axes and orthogonal to the development axes B of the lamellas. The lamellas 201 are supported in their parallel condition spaced by a distance d between adjacent lamellas 201 by a support structure 220', the distance d being preferably variable between a maximum distance d_max in which the unit 200' assumes an open configuration and a minimum distance d_min in which the lamellas 201 assume a retracted configuration. In the embodiment of Fig. 5 the support structure 220' comprises a plurality of suspension ties 225 connected to an upper support bar 226. The suspension ties 225 are tied to the lamellas 201 in a known manner, so as to be able to control them all simultaneously in rotation, each around an axis of rotation parallel or coincident with its barycentre axis B and/or so as to be able to change the relative distance between an open configuration and the closed retracted configuration.
Alternatively, according to an embodiment not illustrated, the relative distance d can be modified by translating the coupling points of the axes of rotation on the side uprights of a sunshade type unit (unit of the type illustrated in Fig. 1).
Also in this case, the lamellas employed in the daylight management unit comprise a first non-planar upper face, defining an upper surface 211 having at least one portion with upwardly facing concavity preferably in all the operating positions that can be assumed by the lamellas when the unit 200' is in configuration of use and at least one reflective portion, which preferably coincides with the portion with upwardly facing concavity. The lamellas further comprise a second lower face defining a lower surface 212. In particular, the lower surface 212 has at least one reflective portion 213, preferably arranged at an entry side end 201a of the lamella and configured to redirect upwards the rays reflected by a portion 214 of the upper surface 211 of an underlying lamella 201, preferably placed at an entry side end 201b, opposite the exit end 201a. Furthermore, the lower surface 212 preferably comprises a shielding portion 215, adjacent the reflective portion 213 and extending towards the entry side end 201b of the lamella opposite the exit end 201a. Further, at least part of the lower surface 212 of the lamellas 201 has a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red.
In the embodiment of Fig. 5, the daylight management unit 200' is supported in a configuration suspended to the upper support bar 226 and between a pair of panels 227 that are at least partially transparent to visible light, for example made of glass, constrained in such a way as to define between them a hollow housing chamber in which the unit 200' is arranged. In the embodiment of Fig. 5, the two transparent panels 227 are constrained to a support frame 228 including also the upper support bar 226. The unit 200' of Fig. 5 is usually used for the construction of so-called "double skin" buildings.
In the embodiment of Fig. 5, the internal angle θ formed between the shielding portion 215 and the reflective portion 213 is defined with reference to the maximum distance d_max between adjacent lamellas 201.
With reference to Fig. 6 there is schematically illustrated a third embodiment of a daylight management unit 200" according to the present invention. The unit 200" of Fig. 6 comprises a plurality of lamellas 201 each having an elongated development along a respective development axis C of the lamella. The lamellas 201 therefore have two opposing faces surrounded by perimeter walls having a much more pronounced extension along a first development direction parallel to the axis C, with respect to a second development direction of said walls, and head walls orthogonal to the axis C. The lamellas 201 have a section orthogonal to the development axis C that is substantially constant having a barycentre B and the set of the barycentres B of the sections defines a barycentre axis. The lamellas 201 are arranged parallel to each other, so that their barycentre axes B are all comprised in the same plane of the axes, and spaced from each other along a direction comprised in the plane of the axes and orthogonal to the barycentre axes B. With the unit installed for use, the lamellas 201 are supported with their development axes C orthogonal to a vertical plane so that the plane of the axes comprising them is a vertical plane; the direction along which the lamellas are spaced from each other is, specifically, the vertical direction. In particular, in the embodiment of Fig. 6, the lamellas are fixedly constrained to a support structure 220. Preferably, the fixed support structure comprises at least a pair of vertical uprights 222, for example uprights conforming to substantially flat panels as illustrated in Fig. 6, or uprights conforming to cylinders that cross and support the lamellas, and each lamella 201 is spaced apart from the adjacent lamellas by a distance d measured in the plane of the barycentre axes as the distance between the respective barycentre axes B.
As illustrated in Fig. 7, the lamellas 201 employed in the unit 200" of Fig. 6 comprise a first non-planar upper face, defining an upper surface 211 having in use at least an upwardly facing concavity and preferably reflective portion. The lamellas 201 employed in the unit 200" of Fig. 6 further comprise a second lower face defining a lower surface 212 having at least one reflective portion 213 placed at an entry side end 201a of the lamella 201 and configured to redirect upwards the rays reflected by a reflective portion 214 of the upper surface 211 of an underlying lamella 201, preferably placed at an entry side end 201b, opposite the exit end 201a. With reference to the exit end 201a and to the entry end 201b, it is to be considered that, in general terms, the unit 200" is configured to be mounted at a transparent structure of a building with the entry side end 201b facing the natural light source, i.e. outwards with respect to the environment delimited by the transparent structure.
The reflective portion 213 of the lower surface may have a planar conformation or have downwardly facing concavity in use, in particular to cooperate with the portion with upwardly facing concavity of the upper surface 211 of an underlying lamella in order to redirect upwardly the rays therefrom reflected.
Furthermore, the lower surface 212 preferably comprises a shielding portion 215, adjacent the reflective portion 213 and extending towards an entry side end 201b of the lamella opposite the exit end 201a. Further, at least the reflective portion 213 of the lower surface 212 of the lamellas has a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red.
In particular, as shown in Figs. 8 and 9, the diffusion layer in Rayleigh-like regime or chromatic diffusion layer 202 is a layer applied to at least the reflective portion 213 of the lower surface 212 of the lamella.
In particularly advantageous embodiments, the upper surface 211 of the lamella 201 is also at least partially or entirely coated with a diffusion layer in Rayleigh-like regime or chromatic diffusion layer 202, as shown in Fig. 9. In particular, the upper surface 211 of the lamella 201 is coated with a chromatic diffusion layer 202 at least at the reflective portion 214 of the upper surface 211, preferably placed at the entry side end 201b of the lamella 201, opposite the exit end 201a.
In alternative embodiments not illustrated, the upper surface 211 of the lamella 201 is coated with a chromatic diffusion layer 202 at least at the exit portion in proximity of the exit side end 201a.
Figs. 10a and 10b show different conformations that the lower surface 212 can assume as a function of the distance d between adjacent lamellas 201 and with the same width of the lamellas measured as a tip-to-tip distance in the orthogonal section plane. In particular, Fig. 10a shows a lower surface 212 with a pointed shape given for example by an acute angle θ which is formed internally between the reflective portion 213 and the shielding portion 215. This conformation is particularly suitable in case of a high distance d, allowing to prevent the entry of rays for low angles of incidence of the light (for example of about 10° or less). On the contrary, Fig. 10b illustrates a flattened conformation of the lower surface 212, given for example by an obtuse angle θ that is formed internally between the reflective portion 213 and the shielding portion 215. This conformation is particularly suitable in case of a reduced distance d and allows to prevent the entry of rays for low angles of incidence of the light.
The operation of the daylight management unit according to the present invention is schematically illustrated in Figs. 11-14 with reference to the case in which the lamellas 201 are made as illustrated in Figure 2, and in Figures 15-17 with reference to the case in which the lamellas 201 are made as illustrated in Fig. 7.
In particular, the Figs. 11 and 15 illustrate the unit 200,200',200'' with the lamellas 201 arranged according to a first inclination with respect to the sunlight 300 incident thereon, such as to regularly reflect it upwards through multiple reflections between adjacent pairs of lamellas 201. A spectral portion 301 of mainly regularly reflected sunlight is thus outside the field of view of an observer standing in the interior environment in front of the unit 200,200,200". Otherwise, a spectral portion of mainly diffusedly reflected sunlight 302 is visible to an observer staying in the interior environment delimited by the unit 200,200',200". As shown in Figs. 11 and 15, the two portions of light reaching the interior environment will have two different colour correlated temperatures or CCT: the spectral portion 301 of mainly regularly reflected sunlight results to have a first colour correlated temperature CCT₁ lower than a second colour correlated temperature CCT₂ of the spectral portion of mainly diffusedly reflected sunlight 302, preferably the second colour correlated temperature CCT₂ is at least 1.2 times, preferably 1.3 times, more preferably 1.5 times, even more preferably 1.8 times greater than the first CCT₁, and/or a CCT equal to 5600 Kelvin.
Fig. 12 schematically compares two different inclinations of the lamellas 201 with reference to the same angle of incidence α of the sunlight, showing in particular how the incident rays are regularly reflected upwards, in this way being directed out of the field of view of an observer staying in the interior environment in front of the unit 200,200'.
Fig. 13 as well as Fig. 16 show multiple reflections between pairs of adj acent lamellas as a function of the angle of incidence α of the sunlight. Also in this case it is possible to appreciate that the incoming rays are regularly reflected upwards for all the inclinations typically assumed by sunlight as a function of the time of day and the period of year.
Finally, in Figs. 14 and 17 there are schematically illustrated the external and internal sides of observation, illustrating on the left how the external side of the unit 200,200',200" appears to an observer staying in front of it and on the right how the internal side appears to an observer staying in front of it. Thus, as depicted in Figs. 14 and 17, the internal side of the unit 200,200',200" appears to have a uniform light bluish colouring of the hue of a clear sky, due to the greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red. The light bluish colouring given by the greater diffused reflectivity for wavelengths in the range of the blue is therefore completely independent of the colouring assumed by the sky, as it can be reproduced even at night, if the unit is struck by a beam of artificial white light, for example the light projected by a streetlamp or other dedicated lighting.

Claims

Daylight management unit (200,200',200") comprising
a plurality of lamellas (201) each having an elongated development along a respective development axis (C) of lamella, each lamella (201) having two opposing faces having a much more pronounced extension along a first direction parallel to the development axis (C) and a section orthogonal to the development axis (C) that is substantially constant and having a barycentre (B), the set of barycentre of the sections defining a barycentre axis (B), the lamellas (201) being arranged parallel to each other with the barycentre axes (B) comprised in a same plane of the axes and spaced apart along a distancing direction comprised in the plane of the axes and orthogonal to the barycentre axes (B), and

a structure (220,220') of support of the lamellas configured to support the plurality of lamellas (201) in the condition of parallel lamellas,

wherein, in the configuration of use of the unit (200,200',200"), each lamella (201) of the plurality of lamellas (201) comprises a first non-planar upper face, defining an upper surface (211) comprising at least one portion having, with reference to a section plane orthogonal to the development axis (C), an upwardly facing concavity and at least one reflective portion (214), and a second lower face defining a lower surface (212),

characterized in that at least one between the upper surface (211) and the lower surface (212) comprises at least a portion coated with a diffusion layer (202) configured to provide a greater regular reflectance for wavelengths of the incident light comprised in the range of the red than wavelengths of the incident light comprised in the range of the blue and a greater diffused reflectance for wavelengths of the incident light comprised in the range of the blue than wavelengths of the incident light comprised in the range of the red, wherein the diffusion layer comprises a plurality of diffusion nanometric elements made of a first material having a first refractive index (n₁,n_P), immersed in a second material having a second refractive index (n₂,n_h) other than the first (n₁,n_p), wherein a ratio ( $m \equiv \frac{n_{p}}{n_{h}}$
) between the first (n₁,n_p) and the second (n₂,n_h) refractive index, a number (N) of nanometric elements per area unit and an average size of the nanometric elements of the plurality of diffusion nanometric elements referred to a diameter of the smallest cylinder (d_c) that circumscribes them are selected to preferentially diffuse components of incident light at a small wavelength with respect to components of incident light at a large wavelength and to preferentially transmit components of incident light at a large wavelength with respect to components of incident light at a small wavelength.
Unit (200,200',200") according to claim 1, wherein the at least one upper surface portion having upwardly facing concavity is the reflective upper surface portion (214).
Unit (200,200',200") according to claim 1 or 2, wherein the lower surface (212) comprises at least one reflective portion (213) configured to cooperate with the at least one reflective portion (214) of the upper surface (211) of an adjacent lamella (201) placed below, so as to redirect upward incident rays on the reflective portion (214) of the upper surface (211) of the adjacent lamella (201).
Unit (200,200',200") according to claim 3, wherein the at least one reflective portion (213) of the lower surface (121) of each lamella (201) has a flat shape or has a downwardly facing concavity in use.
Unit (200,200',200") according to claim 3 or 4, wherein the at least one portion coated with a diffusion layer (202) is the at least one reflective portion (213) of the lower surface (212).
Unit (200,200',200") according to any one of claims 3 to 5, wherein the at least one reflective portion (213) of the lower surface (212) of each lamella (201) is arranged at or near an entry side end (201a) of the lamella, with reference to a section orthogonal to the development axis (C) wherein the lamellas have two opposite side ends (201a ,201b) and wherein the at least one reflective portion (214) of the upper surface (211) of each lamella (201) is placed at an entry side end (201b), opposite the exit end (201a).
Unit (200,200',200") according to any one of the preceding claims, wherein the at least one portion coated with a diffusion layer (202) is arranged on the at least one between the upper surface and the lower surface so as to intercept at least 50%, preferably 70%, more preferably 90% of the regularly reflected rays exiting the unit in the case of incident rays having a direction that form an angle of incidence α with a horizontal plane, the angle of incidence α being comprised between 40°-50°, preferably between 30°-60°, more preferably between 20°-70°.
Unit (200,200',200") according to any one of the preceding claims, wherein the at least one portion coated with a diffusion layer (202) extends over at least 10%, preferably over at least 20%, more preferably over at least 30% of the set of the upper (211) and lower (212) surfaces of the lamella (201).
Unit (200,200',200") according to any one of the preceding claims, wherein the at least one portion coated with a diffusion layer (202) is arranged at or near an entry side end (201a) of the lamella (201) with reference to a section orthogonal to the development axis (C) wherein the lamellas have two opposite side ends (201a,201b).
Unit (200,200',200") according to any one of the preceding claims, wherein the diffusion nanometric elements of the diffusion layer (202)
- are substantially transparent or substantially non-absorbent at least with respect to electromagnetic radiations with wavelength comprised in the visible light spectrum,

- have an average size referred to a diameter of the smallest cylinder (d_c) that circumscribes them between 5 nm and 350 nm, preferably between 10 nm-250 nm, more preferably between 40 nm-180 nm, even more preferably between 60 nm-150 nm, and

- are present in the diffusion layer (202) in a number N per unit area as a function of an effective diameter of the element or particle D = d_c n_h (D indicated in [metres]), d_c being the diameter of the smallest cylinder that on average circumscribes said nanometric elements, which falls within the range defined by

- $N \geq N_{\min} = \frac{3.47 \times 10^{- 29}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2} [{metres}^{- 2}]$
, and $N \leq N_{\max} = \frac{1.03 \times 10^{- 27}}{D^{6}} {|\frac{m^{2} + 2}{m^{2} - 1}|}^{2}$
[metres^-2]; and wherein the second material is substantially transparent or substantially non-absorbent at least with respect to electromagnetic radiations with wavelength comprised in the visible light spectrum, and the ratio between the first (n_p) and the second (n_h) refraction index $m \equiv \frac{n_{p}}{n_{h}}$
is comprised in the range 0.5≤m≤2.5, for example 0.7≤m≤2.1 or 0.7≤m≤1.9.
Unit (200,200',200") according to any one of the preceding claims, wherein the diffusion nanometric elements of the diffusion layer (202) are selected from the group consisting of:
- nanometric elements in solid phase,

- nanometric elements in liquid phase,

- nanometric elements in gas phase,

- three-dimensional metal oxides

- nano-pores,

- nano-channels and

- nano-pillars.
Unit (200,200',200") according to any one of the preceding claims, wherein the first material is a metal oxide, such as aluminium oxide (alumina), titanium oxide (titania) or zinc oxide.
Unit (200,200',200") according to any one of the preceding claims,
wherein the second material is air or is selected from a polymer, a resin, a silicone, a different oxide, said second material being at least partially non-absorbent, or transparent at least to electromagnetic radiations with wavelength comprised in the visible light spectrum and having a second refractive index (n₂) comprised between 1.3 and 1.55, preferably between 1.49 and 1.52; or

wherein the second material is a soluble fluoropolymer-based resin, such as a polyurethane resin with a high fluorocarbon content, more preferably a soluble fluoropolymer-based resin with second refractive index (n₂) comprised between 1.45 and 1.50, even more preferably with second refractive index (nz) equal to 1.48.
Unit (200,200' ,200") according to any one of claims 4 to 13, wherein at least the reflective portion (213) of the lower surface (212) of the lamella (201) and the reflective portion (214) of the upper surface (211) of the lamella (201') each comprise at least one tangent point such that the tangents to the surfaces in the section plane orthogonal to the development axis (C) and at the respective tangent points form a smaller angle (γ) of at least 10°, preferably of at least 20°, more preferably of at least 40°; and/or the lower surface (212) of each lamella (201) comprises a shielding portion (215) adjacent to the reflective portion (213) of the lamella (201) and extending towards the entry side end (201b) of the lamella opposite the exit end (201a), the shielding portion (215) being configured to block the passage of light from one side to another of the unit in the absence of reflections on the lamellas (201).
Unit (200,200',200") according to any one of the preceding claims, wherein the upper surface (211) comprises at least a pair of adjacent planar portions inclined to each other in such a way as to define above, in the section plane orthogonal to the development axis (C), an angle (β) of less than 180°.