Lighting equipment that simulates natural light

Abstract

The present invention relates to a lighting device for simulating natural lighting, capable of generating at least two light components with different correlated color temperatures or CCTs and with various angular distributions. The lighting device thus designed to simulate natural lighting can generate light with two colored components with various angular distributions, while effectively preventing light at a higher color temperature (bluish light) from creating glare effects or imparting unnatural coloration to the environment that natural light from the sky and the sun does not produce.

Description

[Technical Field]

[0001] The present invention relates generally to a lighting device for simulating natural lighting, and in particular sky and sunlight, capable of generating at least two light components with various angular distributions and different correlated color temperatures or CCTs. In particular, the present invention relates to a lighting device capable of generating a first highly collimated light component having a lower CCT than the CCT of a second weakly collimated light component, i.e., having an angular aperture of an intensity profile that is larger than the angular aperture of the highly collimated light component. [Background technology]

[0002] Prior art lighting systems are known that simulate natural lighting, specifically sky and sunlight, and are capable of generating light with colored components having varying angular distributions, with a first component of directional or direct light having a first correlated color temperature or lower CCT, and a second component of diffuse light having a second, higher CCT.

[0003] Exemplary embodiments of such lighting systems can use Rayleigh-type diffusing layers, as described in various patent applications filed by the same applicant, such as WO 2009 / 156347 A1, WO 2009 / 156348 A1, WO 2014 / 076656 A1, and WO 2017 / 0847561 A1. Most known lighting systems use a light source that generates visible light and a panel containing nanoparticles. The panel is illuminated by the light source and functions as a so-called colored or Rayleigh-like diffuser, i.e., it diffuses the incident light in a manner similar to the Earth's atmosphere under clear sky conditions, thereby separating the incident light into a first component of direct light that intersects the panel substantially undiffused and a second component of light that is diffused by the panel. In particular, the diffused light component has a larger CCT than the direct light component, because Rayleigh-like diffusers have a scattering efficiency that is a function of the wavelength of the light, with shorter wavelengths having a greater scattering efficiency.

[0004] The interplay between the direct component with a lower CCT, which illuminates objects and casts their shadows, and the diffuse light with a higher CCT (which gives the shadows a bluish coloration), allows the lighting system to faithfully reproduce solar illumination and thus give the environment the perception of a large space.

[0005] However, this effect is strongly mitigated in some environments when known lighting devices that simulate natural lighting are used in combination with secondary lighting devices that produce conventional white light. The addition of secondary lighting devices is usually aimed at achieving greater illuminance than that provided by the natural lighting system alone, while maintaining the overall cost of illuminating the contained environment.

[0006] In these situations, the spatial expansion effect provided by lighting systems that simulate natural light is practically not perceptible at all, since conventional secondary lighting cannot produce the intensity and color contrast typical of natural light.

[0007] Therefore, the applicant has observed that it is convenient to use a secondary lighting device capable of generating light with colored components having various angular distributions with colored characteristics and angular apertures of intensity profile that match the light components generated by the lighting system that simulates natural lighting, so as not to change the perception provided by the lighting system that simulates natural lighting.

[0008] Therefore, the applicant set himself the goal of designing a lighting device that simulates natural lighting that can be used as a secondary lighting device in combination with a lighting system that simulates natural lighting.

[0009] In particular, the applicant set himself the object of realizing a lighting device that simulates natural lighting, which makes it possible to increase the overall lighting provided by a lighting system that simulates natural lighting without changing the perception provided, and which can be realized at a reasonable cost.

[0010] Furthermore, the applicant has set himself the objective of devising a lighting device that simulates natural lighting that can be used to achieve localized natural lighting for illuminating a limited area, such as a work surface, desk, table, etc.

[0011] In particular, the applicant has been keen to research a lighting device that simulates natural lighting, which provides high lighting efficiency and is able to reproduce natural lighting without presenting glare effects or unnatural coloring of the ceiling of the room in which it is installed. Summary of the Invention [Means for solving the problem]

[0012] In a first aspect, the present invention relates to a lighting device for simulating natural lighting, comprising a first optical unit comprising, in order: a primary light source configured to emit primary light within the visible spectrum; and a dichroic separation optics configured to block at least a portion of the primary light generated by the primary light source and to emit from a first light-emitting surface at least one first highly collimated light component and at least one diffused light component having propagation directions originating from the primary light, wherein the at least one first highly collimated light component and the at least one diffused light component form light with colored components having different angular distributions.

[0013] Furthermore, the at least one first highly collimated light component has a first correlated color temperature (CCT1), a total luminous flux, and an emission intensity profile characterized by a first angular aperture (α) that is less than 30°, measured as a half width at half maximum (HWHM) with reference to at least one half-plane cross section of the dichroic separation optical system that includes the propagation direction.

[0014] Furthermore, at least one diffuse light component has a second correlated color temperature (CCT2) higher than the first correlated color temperature (CCT1) and a non-zero luminous intensity profile, e.g., a substantially Lambertian luminous intensity profile, for angles greater than twice the first angular aperture (α).

[0015] A substantially Lambertian emission profile means an emission profile proportional to the cosine of the emission angle, the emission angle being understood to be equal to 0° relative to the normal to the emission surface.

[0016] According to the present invention, there is also provided a second optical unit, which includes a secondary collimation optics configured to block at least a portion of the light with colored components having various angular distributions emitted by the first light-emitting surface, and to generate, starting from this light with colored components having various angular distributions, a weakly collimated light component and a second highly collimated light component. The weakly collimated light component has an emission intensity profile characterized by a mean value calculated with reference to a half-plane cross section and with reference to an attenuation angle range comprised between the attenuation angle (γ) and 90°, which is smaller than the mean value of the emission intensity profile of at least one diffuse light component calculated with reference to the same attenuation angle range. The attenuation angle (γ), measured relative to the direction of propagation, is equal to at least two times the first angular aperture (α) of the emission intensity profile of the first highly collimated light component emitted by the first emitting surface. The second highly collimated light component (34a) has substantially the same total luminous flux as the first highly collimated light component and has a second emission intensity profile angular aperture (α') that is equal to or smaller than the first emission intensity profile angular aperture (α) of the first highly collimated light component emitted by the first light emitting surface. The weakly collimated light component and the second highly collimated light component form a collimated light with colored components having various angular distributions that is emitted by the second optical unit.

[0017] In this way, a lighting device that simulates natural lighting can generate light with two colored components with different angular distributions, while effectively preventing light of a higher color temperature (bluish light) from causing glare effects or imparting unnatural coloration to the environment that natural light from the sky and the sun does not produce, while maintaining the lighting efficacy substantially unchanged.

[0018] The lighting device according to the present invention can thus be effectively used as a secondary lighting device supporting lighting systems that simulate natural lighting (the generation of colored components with various angular distributions can support the natural lighting effects that these systems reproduce) and as a local lighting device that can provide good lighting efficiency without glare effects.

[0019] According to a second aspect, the invention relates to an illumination device for simulating natural illumination, comprising a plurality of illumination devices of the type described above arranged to generate a plurality of highly collimated light components around respective ones of a plurality of parallel propagation directions, the illumination devices being arranged in an elongated configuration in a plane perpendicular to each of the propagation directions.

[0020] Advantageously, a lighting device constructed in this way makes it possible to achieve the same advantages as those explained with reference to the lighting device according to the invention for simulating natural lighting.

[0021] The present invention may have at least one of the following preferred features, which may be combined with each other as needed to meet specific application needs.

[0022] Preferably, the at least one first highly collimated light component has an emission intensity profile characterized by a first angular aperture (α), measured as a half width at half maximum (HWHM) with reference to at least one half-plane cross section of the dichroic separation optics that includes the propagation direction, that is less than 20°, more preferably less than 15°.

[0023] Preferably, the attenuation angle (γ) is at least equal to 2.5 times, more preferably equal to 3 times, the first angular aperture (α) of the luminous intensity profile of the first highly collimated light component emitted by the first emitting surface.

[0024] In a variant of the invention, the secondary collimation optical system is configured to generate a weakly collimated light component having an emission intensity profile referenced to a half-plane cross section, characterized by an average value of less than 60%, preferably less than 40%, more preferably less than 20% of the average value of the emission intensity profile of at least one diffuse light component calculated based on the attenuation angle range.

[0025] The secondary collimation optics is configured to substantially not block and / or not redistribute and / or redirect the highly collimated light components outside the first angular aperture (α), and in particular is configured to block and / or redistribute and / or redirect less than 10%, preferably less than 5%, and more preferably less than 2% of the total luminous flux of the highly collimated light components exiting the first light-emitting surface 25 outside the first angular aperture (α).

[0026] In a variant of the invention, the secondary collimation optical system is embodied as a refractive lens configured to intercept and reflect at least a portion of the at least one diffuse light component and redistribute it to generate a weakly collimated light component having an emission intensity profile with reference to a half-plane cross section, characterized by an average value lower than the average value of the emission intensity profile of the at least one diffuse light component calculated with reference to the attenuation angle range.

[0027] Alternatively or additionally, the secondary collimation optics is embodied as a refractive lens configured to intercept and redirect at least a portion of the at least one diffuse light component and redistribute it to generate a weakly collimated light component having an emission intensity profile with reference to a half-plane cross section characterized by an average value lower than the average value of the emission intensity profile of the at least one diffuse light component calculated with reference to an attenuation angle range.

[0028] Preferably, the refractive lens is configured to additionally intercept and redirect at least a portion of the first highly collimated light component, thereby generating a second highly collimated light component having an emission intensity profile characterized by a second angular aperture (α'), measured as a half width at half maximum (HWHM) referenced to a half-plane cross section, that is equal to or preferably lower than the first angular aperture (α).

[0029] Alternatively or additionally, the secondary collimation optics is a structure including a wall having at least a portion made of a material having a diffuse reflectance of at least 50%, preferably at least 55%, more preferably at least 60%.

[0030] Alternatively or additionally, the secondary collimation optics is a structure including a wall having at least a portion made of a material having an absorption coefficient in the visible region equal to at least 70%, more preferably at least 80%, and even more preferably at least 90% of the incident light, and is positioned to intercept and absorb at least a portion of the diffuse light component emitted by the first light-emitting surface at angles greater than the attenuation angle (γ).

[0031] In this specification and the claims that follow, the terms "absorption coefficient," "specular reflectance," and "diffuse reflectance" refer to the definitions given in Standard E284 for terminology describing the appearance of materials and light sources.

[0032] Preferably, the secondary collimation optics is configured not to substantially modify the correlated color temperature CCT of the light components with colored components having different angular distributions emitted by the first optical unit.

[0033] Preferably, the secondary collimation optical system is configured to generate, starting from light having colored components with various angular distributions emitted by the first light-emitting surface, a weakly collimated light component having a correlated color temperature substantially equal to the second correlated color temperature CCT2 of the diffused light component of the light emitted by the first light-emitting surface, and a second highly collimated light component having a first correlated color temperature substantially equal to the first correlated color temperature CCT1 of the first highly collimated light component of the light emitted by the first light-emitting surface.

[0034] In a variant of the invention, the angular aperture (β) of the weakly collimated light component, measured as the half width at half maximum (HWHM) of the light intensity profile with reference to a half-plane cross section, is 1.2 times larger, preferably 1.5 times larger, and more preferably 2 times larger than the first angular aperture (α) measured as the half width at half maximum (HWHM) of the intensity profile of the first highly collimated light component.

[0035] In a variant of the invention, the dichroic separation optical system comprises a primary collimation optical element configured to generate, starting from the primary light, a highly collimated light component having an emission intensity profile with a first angular aperture (α), and a diffused light generator configured to generate a diffused light component with a second correlated color temperature.

[0036] Preferably, the diffuse light generator is a colored scattering element that is transparent to at least a first spectral portion of light incident thereon and configured to scatter at least a second spectral portion of the light incident thereon.

[0037] Alternatively or additionally, the diffused light generator is a tunable colored scattering element configured to primarily vary the scattering efficiency of the colored scattering element in at least a second spectral portion of the incident light, thereby adjusting the scattering efficiency of the second spectral portion of the incident light.

[0038] Alternatively or additionally, the diffuse light generator is a tunable colored scattering element that includes a matrix made of a polymer material in which nanodroplets containing liquid crystals are trapped.

[0039] Alternatively or additionally, the diffuse light generator is a colored scattering element shaped as a panel, a film, a surface coating layer, or a surface anodized layer.

[0040] Alternatively or additionally, the diffuse light generator is an active diffuse light generator capable of generating diffuse light independent of the primary light source and made of a material that is substantially transparent to light regardless of its spectrum.

[0041] More preferably, the colored scattering elements are arranged on at least one of the first light emitting surface or the surface of interaction between said primary light and said primary collimation element.

[0042] In a variant of the invention, the primary collimation optical element (23a) of the dichroic separation optical system (23) has axial symmetry, the propagation direction is contained in the axis of symmetry of the primary collimation optical element, and the diffused light generator has a circular or quadrangular (e.g. square or rectangular) or polygonal cross section.

[0043] In an alternative variant of the invention, the primary collimating optical element of the dichroic separation optics has an elongated structure along the development axis of the device, transverse to the propagation axis.

[0044] In a variant of the invention, the first optical unit comprises, for example, a plurality of primary light sources arranged next to each other and / or aligned along the unfolding axis, and the dichroic separation optics comprises at least one collimation lens associated with the plurality of primary light sources and configured to collimate the light emitted by each of the primary light sources around an individual one of the plurality of parallel propagation directions. [Brief explanation of the drawings]

[0045] The accompanying drawings, which are incorporated herein and form a part of this description, illustrate exemplary embodiments of the invention and, together with the description, are intended to explain the principles of the invention. [Figure 1] 1 is a schematic diagram of a first embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 2] FIG. 2 is a schematic diagram of a second embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 3] FIG. 10 is a schematic diagram of a third embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 4] FIG. 10 is a schematic diagram of a fourth embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 5] FIG. 10 is a schematic diagram of a fifth embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 6] FIG. 10 is a schematic diagram of a sixth embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 7] FIG. 10 is a schematic diagram of a seventh embodiment of a lighting device for simulating natural lighting according to the present invention. [Figure 8] 1 is a schematic diagram of an embodiment of a lighting system including a plurality of lighting devices for simulating natural lighting according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0046] 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 teach the principles of the present invention and enable those skilled in the art to implement and use the present invention in different situations and / or for different applications. Therefore, the exemplary embodiments are not intended to, nor should they be considered to, limit the scope of patent protection. Rather, the scope of patent protection is defined by the appended claims.

[0047] Referring to FIG. 1, a lighting device for simulating natural light (hereinafter referred to as "lighting device" for brevity) according to a first embodiment of the present invention is shown schematically and generally designated 10.

[0048] The lighting device 10 comprises a first optical unit 20 and a second optical unit 30 coupled to each other such that the second optical unit 30 blocks at least a portion of the light emitted by the first optical unit 20 .

[0049] In particular, the first optical unit 20 comprises at least one primary light source 21 configured to emit primary light 22 (hereinafter also referred to with the terms "light beam", "ray" or "light") comprising at least one set of electromagnetic radiation having wavelengths comprised in the visible spectrum (i.e. 380 nm≦λ≦740 nm). For example, the primary light source 21 is a solid state light emitting device (LED).

[0050] The first optical unit 20 further comprises at least a dichroic separation optics 23 having a first light emitting surface 25 from which light 24 is emitted with colored components having different angular distributions. The primary light source 21 is positioned to substantially introduce the primary light 22 into the dichroic separation optics 23.

[0051] The dichroic separation optical system 23 starts from the primary light 22 emitted by the primary light source 21, intersects with the first light-emitting surface 25, and generates at least a first highly collimated light component 24a propagating along a propagation direction A, the propagation direction A coinciding with the direction in which the first highly collimated light component 24a exhibits maximum luminous intensity, and generates a diffuse light component 24b intersecting with the first light-emitting surface 25 and propagating in substantially all directions. For example, the diffuse light component 24b has a substantially Lambertian luminous intensity profile.

[0052] The first highly collimated light component 24a generated by the dichroic separation optical system 23 is characterized by an emission intensity profile, which has an angular aperture α, measured in terms of half width at half maximum (HWHM), with reference to at least one half-planar cross section X of the dichroic separation optical system 23, including the propagation direction A, which is less than 30°, preferably less than 20°, and more preferably less than 15°. Furthermore, the first highly collimated light component 24a is characterized by a first correlated color temperature or CCT1 and a total luminous flux.

[0053] The dichroic separation optical system 23 is further configured to generate at least one diffuse light component 24b with a second correlated color temperature CCT2 that is significantly higher or different than the correlated color temperature CCT1 of the first highly collimated light component 24a. Specifically, the first highly collimated light component 24a has a correlated color temperature CCT1 that is 1.2 times lower, preferably 1.3 times lower, and more preferably 1.4 times lower than the correlated color temperature CCT2 of the diffuse light component 24b.

[0054] In exemplary terms, the dichroic separation optics 23 comprises a primary collimation optic 23a (e.g., a total internal reflection (TIR) ​​lens as shown in FIG. 1 or a reflector as shown in FIG. 2) and diffuse light generators 23b, 23b′, 23b″, which in the embodiment of FIG. 1 are fabricated as colored scattering elements 23b and are arranged at the first light-emitting surface 25 so as to block the collimated light exiting the primary collimation optics 23a. In particular, the primary collimation optics 23a in the embodiment of FIG. 1 has axial symmetry, such that the emission intensity profile of the first highly collimated light component 24a is substantially equal with reference to a half-planar cross-section X of the dichroic separation optics 23, which contains the propagation direction A. The colored scattering element 23b may also be axially symmetric, for example, realized with a circular cross-section, or may not be axially symmetric with a quadrilateral cross-section, such as a square or rectangle, or may or may not have a regular polygonal cross-section.

[0055] By "colored diffusing element" is meant a diffusing element whose light diffusing properties depend on the wavelength of light intersecting it, e.g., a Rayleigh or Rayleigh-like diffuser. This type of diffuser is characterized by being substantially transparent to, or having negligible interaction with, a first spectral portion of light incident on it.

[0056] Thus, the first spectral portion of the incident light intersects the colored scattering element 23b substantially unchanged and is collimated as a result of the action of the primary collimation optics 23a, generating a first highly collimated light component 24a of light 24 downstream of the colored scattering element 23b, with colored components having a different angular distribution and a lower correlated color temperature CCT1. "Downstream" is understood with reference to the propagation direction A. In contrast, the colored scattering element 23b acts primarily on the second spectral portion of the light incident on it, significantly scattering it and producing a diffuse light component 24b of light 24 with colored components having a different angular distribution and a higher correlated color temperature CCT2, since it is substantially devoid of wavelengths belonging to the first spectral portion.

[0057] The color separation and generation of a diffuse light component 24b with a higher CCT2 (a bluish light component) can be achieved by using a "thick" panel, as shown by way of example in Figure 1, or a "thin" layer, as shown by way of example in Figure 5, which is generally referred to herein as a "colored scattering element 23b," and which comprises a layer within a host material in which transparent nanometer scattering elements (also known as "scattering elements") are present in a predetermined amount per unit area and have a refractive index that differs from the refractive index of the host material.

[0058] Such colored scattering elements may be in the form of panels, films, surface coating layers, or surface anodized layers on metal surfaces having specific structural characteristics as described in detail in Italian Patent Application No. 1020200008113 filed by the same applicant, the contents of which are incorporated herein by reference in their entirety.

[0059] The colored scattering elements may also be tunable, allowing the strength of interaction between the colored scattering elements and the incident light to be adjusted, thereby changing the diffusion efficiency, particularly for the second spectral portion of the incident light, i.e., the portion of the incident light that the colored scattering elements primarily affect. A tunable colored scattering element may, for example, comprise a matrix made of a polymeric material (host material) in which so-called nanodroplets containing liquid crystal (LC) molecules (diffusing nanometer elements) are trapped. Because liquid crystals exhibit anisotropy in their refractive index, it is possible to adjust the refractive index jump between the liquid crystal nanodroplets and the host material by varying the applied voltage. Generally, the refractive index change is due to the tendency of the liquid crystal molecules within each nanodroplet to orient when an electric field is applied, with the degree of orientation being adjustable according to the magnitude of the applied voltage. For further details, reference is made to International Patent Application Publication No. 2018 / 091150 of the same applicant, the contents of which are incorporated herein by reference in their entirety.

[0060] The embodiment shown in FIG. 2 differs from the embodiment shown in FIG. 1 in that it includes an active diffused light generator 23b', i.e., the diffused light 23b' can be generated independently of the primary light source 21, disposed on the first light-emitting surface 25. In particular, the diffused light generator 23b' generates a diffused light component 24b with a correlated color temperature CCT2 higher than that of the light 24 having colored components with various angular distributions emitted by the first light-emitting surface 25. Furthermore, the diffused light generator 23b' is made of a material that is substantially transparent to light, regardless of its spectrum. Thus, most of the collimated light that exits the primary collimation optical element 23a and is blocked by the diffused light generator 23b' propagates downstream in the propagation direction A, enhancing the first highly collimated light component 24a of the light 24 having colored components with various angular distributions emitted by the first light-emitting surface 25.

[0061] The second optical unit 30 comprises at least one secondary collimation optical system 33. The secondary collimation optical system 33 has a light input surface 36 arranged downstream of the first light-emitting surface 25 of the first optical unit 20 so as to block at least a portion of the light 24 having colored components with various angular distributions emitted by the first optical unit 20, and a second light-emitting surface 35 from which the collimated light 34 having colored components with various angular distributions is emitted.

[0062] In particular, the secondary collimation optical system 33 is configured to interact with the diffuse light component 24b of the light 24 emitted by the first optical unit 20 to generate, downstream of the second light-emitting surface 35, a weakly collimated light component 34b having an emission intensity profile, referenced to at least one half-plane cross section X of the dichroic separation optical system 23, characterized by an average value calculated with reference to an attenuation angle range comprised between the attenuation angle γ and 90° and which is smaller than the average value of the emission intensity profile of the at least one diffuse light component 24b calculated for the same attenuation angle range.

[0063] In particular, the attenuation angle γ is equal to at least two times, preferably at least 2.5 times, and more preferably at least three times the first angular aperture α of the emission intensity profile of the first highly collimated light component 24a emitted by the first light-emitting surface 25, measured relative to the propagation direction A.

[0064] For example, the secondary collimation optics 33 is configured to generate the weakly collimated light component 34b having an emission intensity profile, calculated over an attenuation angle range, i.e., an angular range comprised between the attenuation angle γ and 90°, with reference to the half-plane cross section X, characterized by an average value of less than 60%, preferably less than 40%, more preferably less than 20% of the average value of the emission intensity profile of the diffuse light component 24b exiting the first light-emitting surface 25. This allows the lighting device 10 to be characterized by minimal glare for angles within the attenuation angle range with reference to at least one half-plane cross section X, while maintaining a high luminous efficacy level of the lighting device.

[0065] Furthermore, the secondary collimation optics 33 is configured to interact with the first highly collimated light component 24a of the light 24 emitted by the first light-emitting surface 25 to generate a second highly collimated light component 34a having substantially the same total luminous flux as the first highly collimated light component 24a, and a second angular opening aperture α' of an emission intensity profile that is equal to or smaller than the first angular aperture α of the emission intensity profile of the first highly collimated light component 24a emitted by the first light-emitting surface 25, for example, by not blocking the first highly collimated light component 24a as shown in Figures 1-3, or by not redistributing or redirecting it outside the angular aperture α as shown in Figure 4. In other words, the second collimation optics 33 is configured to keep the angular aperture α of the emission intensity profile of the first highly collimated light component 24a substantially unchanged, or at most reduce it, or not substantially change its total luminous flux. For example, the secondary collimation optics 33 is configured to attenuate less than 10%, preferably less than 5%, and more preferably less than 2% of the total luminous flux of the first highly collimated light component 24a exiting the first light-emitting surface 25.

[0066] Furthermore, the secondary collimation optical system 33 is configured not to substantially change the correlated color temperature CCT of the light component 24 having colored components with various angular distributions emitted by the first optical unit 20. At the exit from the second light-emitting surface 35, a weakly collimated light component 34b having a correlated color temperature substantially equal to the second correlated color temperature CCT2 of the diffuse light component 24b of the light 24 emitted by the first optical unit 20 and a second highly collimated light component 34a having a correlated color temperature substantially equal to the first correlated color temperature CCT1 of the first highly collimated light component 24a of the light 24 emitted by the first light-emitting surface 25 are thus generated. The combination of these light components 34a and 34b forms the collimated light 34 having colored components with various angular distributions emitted by the second light-emitting surface 35 of the second optical unit 30.

[0067] In particular, the weakly collimated light component 34b is characterized by an emission intensity profile with an angular aperture β that is larger than the angular aperture α' of the intensity profile of the second, highly collimated light component 34a, both intensity profiles being referenced to at least one half-plane cross section X of the dichroic separation optical system 23.

[0068] For example, the angular aperture β of the weakly collimated light component 34b has a half width at half maximum (HWHM) that is 1.2 times larger, preferably 1.5 times larger, and more preferably 2 times larger than the angular aperture α' of the intensity profile of the second highly collimated light component 34a.

[0069] 1 and 2, the secondary collimation optics 33 is a structure including internal opaque walls positioned to diffusely reflect at least a portion of the diffuse light component 24b emitted at angles greater than the attenuation angle γ, such that the material from which these walls are constructed has a diffuse reflectance at least equal to 50%, preferably at least 55%, more preferably at least 60%.

[0070] 3, there is shown a schematic representation of a different embodiment of the illumination device 10. In particular, the embodiment of FIG. 3 differs from the first embodiment in the implementation of the dichroic separation optics 23 and the secondary collimation optics 33.

[0071] In the embodiment of FIG. 3, the dichroic separation optical system 23 includes an active diffused light generator 23b'. Furthermore, the secondary collimation optical system 33 is fabricated as a reflector and includes an internal reflective wall configured to intercept and reflect at least a portion of the diffused light component 24b and redistribute it so as to attenuate it at an angle greater than an attenuation angle γ, measured relative to the propagation direction A and referenced to at least one half-plane cross section X, equal to at least two, preferably 2.5, and more preferably three times the angular aperture α of the emission intensity profile of the first highly collimated light component 24a. To this end, the material from which the internal wall is made has a specular reflectivity of at least 60%, preferably at least 65%, and more preferably at least 70%. The secondary collimation optical system 33 is also configured not to intercept the first highly collimated light component 24a of the light emitted by the first light-emitting surface 25.

[0072] Referring to Figure 4, another embodiment of an illumination device 10 according to the invention is shown schematically. In particular, the embodiment of Figure 4 differs from the previous embodiment in the implementation of the secondary collimation optics 33.

[0073] 4, the secondary collimation optics 33 is embodied as a refractive lens configured to interact with the diffuse light component 24b emitted by the first light-emitting surface 25 of the first optical unit 20 so as to attenuate its luminous intensity for angles greater than the attenuation angle γ, with reference to at least one half-plane cross section X. A weakly collimated light component 34b is thus generated downstream of the second light-emitting surface 35, which has an average value of its luminous intensity profile, calculated for angles comprised between the attenuation angle γ and 90°, that is smaller than the average value of the luminous intensity profile of the diffuse light component 24b calculated over the same angular range.

[0074] Furthermore, the secondary collimation optical system 33 is configured to further collimate the first highly collimated light component 24a of the light emitted by the first light-emitting surface 25, so as to obtain, downstream of the second light-emitting surface 35, a second highly collimated light component 34a having a second angular aperture α' of an emission intensity profile that is lower than the first angular aperture α of the emission intensity profile of the first highly collimated light emitted by the first light-emitting surface 25. In other words, starting from the first highly collimated light component 24a emitted by the first light-emitting surface 25, the secondary collimation optical system 33 is configured to generate the second highly collimated light component 34a and reduce the angular aperture of the emission intensity profile at the reference half-plane while keeping its total luminous flux substantially unchanged.

[0075] Thus, at the exit of the second light-emitting surface 35, there is a weakly collimated light component 34b with a higher correlated color temperature CCT2 and a second highly collimated light component 34a with a lower correlated color temperature CCT1, the latter characterized by a second angular aperture α' of an emission intensity profile that is lower than the first angular aperture α of the emission intensity profile of the first highly collimated light component 24a exiting the first optical unit 20, and a total luminous flux that is substantially equal to the luminous flux of this first highly collimated light component 24a. The combination of these light components 34a, 34b forms the collimated light 34 that is emitted by the second light-emitting surface 35 of the second optical unit 30.

[0076] With reference to Fig. 5, another embodiment of the lighting device 10 according to the invention is shown diagrammatically. In particular, the embodiment of Fig. 5 differs from the other embodiments in that the dichroic separating optics 23 is made as a reflector 23a with walls that interact with the incident light emitted by the primary light source 21, i.e., internal reflecting walls coated with a layer 23b" made of a colored diffusing material. The colored diffusing layer 23b" can be applied by lamination, for example, if the material that constitutes it is of the liquid crystal type. Alternatively, this layer can be grown, for example, as an anodized layer directly on the internal walls of the reflector 23a.

[0077] In this case, the light 22 emitted by the primary light source 21 and incident on the inner wall of the reflector 23a is partly collimated and partly diffused. In particular, a first spectral part of the incident light intersects the colored scattering layer 23b" twice (incident beam and reflected beam) in a substantially unchanged manner and is thus almost exclusively subjected to the collimation effect caused by the reflector 23a. Conversely, a second spectral part of the incident light interacts significantly with the colored scattering layer 23b" coating the inner wall of the reflector 23a and is mainly scattered.

[0078] In this way, two colored components with different angular distributions are generated that exit the dichroic separation optical system 23: a first highly collimated light component 24a with a lower color correlation temperature CCT1 and a diffuse light component 24b with a higher color correlation temperature CCT2.

[0079] To ensure that a large portion of the second spectral part of the emitted primary light 22 interacts with the colored scattering layer 23b to generate a diffuse light component 24b, the lighting device 10 may comprise a screen 27 positioned downstream of the primary light source 21 relative to the propagation direction A, which blocks the direct emission of light emitted by the primary light source 21 via the first light-emitting surface 25.

[0080] FIG. 6 shows a further embodiment of the lighting device 10 according to the invention, in which the dichroic separating optics 23 is embodied as a TIR lens with a portion of the light entrance surface 26 coated with a colored scattering layer 23b″.

[0081] In this case, the light 22 emitted by the primary light source 21 intersects a portion of the light input surface 26 and becomes partly collimated and partly diffused. In particular, a first spectral part of the light intersects a portion of the light input surface 26 and intersects the colored scattering layer 23b" and remains substantially unchanged, thereby being subjected to the collimation effect provided by the lens 23a. In contrast, a second spectral part of the light incident on the colored scattering layer 23b" interacts significantly therewith and is mainly scattered.

[0082] This results in two colored components with different angular distributions exiting the dichroic separation optical system 23: a first highly collimated light component 24a with a lower color correlation temperature CCT1 and a diffused light component 24b with a higher color correlation temperature CCT2.

[0083] 6, the secondary collimation optics 33 is fabricated as a structure including an internal absorbing (dark) wall positioned to absorb at least a portion of the diffuse light component 24b emitted at angles greater than the attenuation angle γ, with reference to at least one half-plane cross section X. To this end, the material constituting said wall has an absorption coefficient in the visible range of at least 70%, more preferably 80%, and even more preferably 90% of the light incident thereon.

[0084] With reference to FIG. 7, a further embodiment of a lighting device 10' according to the invention is shown, presenting an elongated development perpendicular to the plane of FIG.

[0085] In detail, the first optical unit 20 of the device of Figure 7 preferably comprises a plurality of primary light sources 21 arranged side by side and aligned along the elongated extension of the device 10', a dichroic separation optical system 23 associated with the plurality of primary light sources 21 and including at least a collimation optical system 23a and configured to collimate the light emitted by the plurality of primary light sources 21 around a plurality of parallel propagation directions A, each of which is associated with and intersects a respective primary light source 21 of the plurality of primary light sources and configured to generate first highly collimated light components 24a in at least a plurality of parallel half-plane cross sections X of the dichroic separation optical system 23 and each of which includes a plurality of parallel propagation directions A, and a diffuse light generator 23b' configured to generate diffuse light components 24b having a different correlated color temperature, in particular a correlated color temperature CCT2 higher than the correlated color temperature CCT1 of the first highly collimated light components 24a.

[0086] The first highly collimated light component 24a generated by the dichroic separation optical system 23 is characterized by an emission intensity profile with an angular aperture α of less than 30°, preferably less than 20°, more preferably less than 15°, referenced to at least one half-planar cross section X of the dichroic separation optical system 23 containing the propagation direction A.

[0087] In view of the non-axial symmetry of the illumination device 10′ with its elongated extension, the first highly collimated light component 24A generated by the dichroic separation optical system 23 is considered to have an emission intensity profile with an angular aperture of less than or equal to 30° (20° or 15°) relative to a subset of half-plane cross sections X of the dichroic separation optical system 23 that includes the propagation direction A. In particular, the subset of half-plane cross sections X for which this condition is met includes half-planes that are inclined from each other within an angular range of at least 20°.

[0088] The second optical unit 30 of Fig. 7 includes a secondary collimation optical system 33 fabricated as a reflective, opaque, and / or absorptive screen positioned to block only the diffuse light component 24b of the light 24 emitted by the first optical unit 20. The effect of the secondary collimation optical system 33 is to attenuate the emission intensity of the diffuse light component 24b for angles greater than the attenuation angle γ in at least one half-planar cross section X of the dichroic separation optical system 23. In this way, with reference to the specific installation of the lighting device 10' of Fig. 7, it is possible to reproduce a natural lighting effect and prevent the bluish diffuse light component 24b from being unnaturally projected onto the ceiling.

[0089] Furthermore, the secondary collimation optics 33 is configured to keep the first highly collimated light component 24a emitted by the first optical unit 20 substantially unchanged, without substantially changing or significantly reducing the angular aperture α of the emission intensity profile, and without changing the total luminous flux.

[0090] This results in a weakly collimated light component 34b and a second highly collimated light component 34a exiting the second light-emitting surface 35, which form the collimated light 34 emitted by the second optical unit 30 and exits the lighting device 10' according to the present invention. In particular, the highly collimated light component 34a exiting the second optical unit 30 has an angular aperture α' of its emission intensity profile that is equal to or smaller than the angular aperture α of the intensity profile of the first highly collimated light exiting the first optical unit 20, and has a total luminous flux substantially equal to that of this first highly collimated light component 24a.

[0091] In particular, the weakly collimated light component 34b is characterized by an emission intensity profile with an angular aperture β that is larger than the angular aperture α′ of the intensity profile of the second highly collimated light component 23a, both intensity profiles being referenced to at least one half-plane cross section X of the dichroic separation optical system 23.

[0092] 8 shows an illumination system 100 for simulating natural illumination including a plurality of illumination devices 10 of the type shown in FIG. 2, in particular, the primary collimation optical elements 23a of the dichroic separation optical system 23 have axial symmetry, and the illumination devices 10 are configured such that the symmetry axes of the individual primary collimation optical elements 23a are arranged parallel to one another. Furthermore, the illumination devices 10 are arranged in an elongated configuration in a plane perpendicular to each of the symmetry axes of the primary collimation optical elements 23a.

[0093] The invention thus envisioned is susceptible to several modifications and variations, all within the scope of the inventive concept. For example, secondary collimation optics 33 may be realized as a structure including partially absorbing, partially reflecting, and / or partially opaque and partially reflecting, or partially opaque and partially absorbing inner walls, in each case configured to absorb at least a portion of diffuse light component 24b intercepted by optics 33 and to reflect at least a portion of diffuse light component 24b intercepted by optics 33, and configured to attenuate the luminous intensity of diffuse light component 24b for angles higher than attenuation angle γ in at least one half-plane cross section X.

[0094] In conclusion, all the details may be replaced by other technically equivalent elements.

Claims

1. A lighting device (10, 10') for simulating natural light, comprising a first optical unit (20) and a second optical unit (30), The first optical unit (20) comprises: a primary light source (21) configured to emit primary light (22) within the visible spectrum; a dichroic separation optical system (23) configured to block at least a portion of the primary light (22) generated by the primary light source (21) and emit at least one first highly collimated light component (24a) and at least one diffused light component (24b) having a propagation direction (A) and generated from the primary light (22) from a first light-emitting surface (25), wherein the at least one first highly collimated light component (24a) and the at least one diffused light component (24b) form light comprising colored components having various angular distributions (24); The at least one first highly collimated light component (24a) has a first correlated color temperature (CCT １ ), and an emission intensity profile characterized by a first angular aperture (α) that is less than 30°, measured as a half width at half maximum (HWHM) with reference to at least one half-planar cross section (X) of the dichroic separation optics (23) that includes the total luminous flux and the propagation direction (A); At least one diffuse light component (24b) has a first correlated color temperature (CCT １ ) higher than the second correlated color temperature (CCT ２ ) and a non-zero emission intensity profile for angles greater than twice the first angular aperture (α); the second optical unit (30) includes a secondary collimation optical system (33) configured to block at least a portion of the light (24) having colored components with various angular distributions emitted by the first light-emitting surface (25) and generate, starting from the light having colored components with various angular distributions (24), a weakly collimated light component (34b) and a second highly collimated light component (34a); the weakly collimated light component (34b) has an emission intensity profile characterized by an average value calculated with reference to the half-plane cross section (X) and an attenuation angle range comprised between an attenuation angle (γ) and 90°, which is smaller than the average value of the emission intensity profile of the at least one diffuse light component (24b) calculated with reference to the same attenuation angle range, the attenuation angle (γ) being equal to at least twice the first angular aperture (α) of the emission intensity profile of the first highly collimated light component (24a) emitted by the first light-emitting surface (25), measured with reference to the propagation direction (A); the second highly collimated light component (34a) has substantially the same total luminous flux as the first highly collimated light component (24a) and has a second emission intensity profile angular aperture (α′) that is equal to or smaller than the first emission intensity profile angular aperture (α) of the first highly collimated light component (24a) emitted by the first light emitting surface (25); The weakly collimated light component (34b) and the second highly collimated light component (34a) form collimated light (34) having colored components with various angular distributions emitted by the second optical unit (30), in an illumination device (10, 10') that simulates natural light.

2. the secondary collimation optics (33) is configured to generate a weakly collimated light component (34b) having an emission intensity profile with reference to a half-plane cross section (X) characterized by an average value of less than 60% of the average value of the emission intensity profile of the at least one diffuse light component (24b), calculated with reference to an attenuation angular range; 2. The lighting device (10, 10') according to claim 1, wherein the secondary collimation optical system (33) is configured so as not to substantially block and / or not to redistribute and / or redirect the highly collimated light components (24a) outside the first angular aperture (α), in particular so as to block and / or redistribute and / or redirect less than 10% of the total luminous flux of the highly collimated light components (24a) exiting the first light-emitting surface (25) outside the first angular aperture (α).

3. the secondary collimation optical system (33) is made as a light reflection optical system configured to intercept and reflect at least a part of the diffuse light component (24b) and redistribute it to generate a weakly collimated light component (34b) having an emission intensity profile with reference to the half-plane cross section (X) characterized by an average value lower than the average value of the emission intensity profile of the at least one diffuse light component (24b) calculated with reference to an attenuation angle range; and / or the secondary collimation optics (33) is embodied as a refractive lens configured to intercept and reflect at least a portion of the at least one diffused light component (24b) and redistribute it to generate a weakly collimated light component (34b) having an emission intensity profile with reference to a half-plane cross section (X) characterized by an average value lower than the average value of the emission intensity profile of the at least one diffused light component (24b) calculated with reference to an attenuation angular range; The secondary collimation optics (33) is a structure including a wall having at least a portion made of a material with a diffuse reflectance of at least 50%; and / or 3. The lighting device (10, 10') according to claim 1 or 2, wherein the secondary collimation optical system (33) is a structure including a wall having at least a portion made of a material having an absorption coefficient in the visible region equal to at least 70% of the incident light, and is positioned so as to block and absorb at least a portion of the diffuse light component (24b) emitted by the first light-emitting surface (25) at angles greater than the attenuation angle (γ).

4. 4. An illumination device (10, 10') according to any one of claims 1 to 3, wherein the angular aperture (β) of the weakly collimated light component (34b), measured as the half-width at half maximum (HWHM) of the luminous intensity profile with reference to the half-plane cross section (X), is 1.2 times larger than the first angular aperture (α) of the first highly collimated light component (24a), measured as the half-width at half maximum (HWHM) of the luminous intensity profile.

5. The dichroic separation optical system (23) includes a primary collimation optical element (23a) configured to generate, starting from the primary light (22), a highly collimated light component (24a) having an emission intensity profile with a first angular aperture (α); Second Correlated Color Temperature (CCT ２ and a diffused light generator (23b, 23b', 23b") configured to generate a diffused light component (24b) comprising:

6. the diffused light generator (23b, 23b″) is a colored scattering element that is transparent to at least a first spectral portion of the light incident thereon and configured to scatter at least a second spectral portion of the light incident thereon; and / or the diffused light generator (23b, 23b″) is a tunable colored scattering element configured to primarily vary the scattering efficiency of the colored scattering element in at least a second spectral portion of the incident light; and / or the diffuse light generator (23b, 23b″) is a tunable colored scattering element comprising a matrix made of a polymer material in which nanodroplets containing liquid crystal (LC) are trapped; and / or The diffused light generator (23b, 23b″) is a colored scattering element shaped as a panel, a film, a surface coating layer, or a surface anodization layer; and / or 6. The lighting device (10, 10') according to claim 5, wherein the diffused light generator (23b') is an active diffused light generator.

7. 7. The lighting device (10, 10') according to claim 6, wherein the colored scattering element is arranged on at least one of the first light-emitting surface (25) or the surface of interaction between the primary light (22) and the primary collimation optical element (23a).

8. at least a first collimation optical element (23 a) of the dichroic separation optical system (23) has axial symmetry, the propagation direction being included in the axis of symmetry of the first collimation optical element (23 a); The lighting device (10, 10') according to any one of claims 1 to 7, wherein the diffuse light generator (23b) has a circular or square cross section.

9. 8. An illumination device (10, 10') according to any one of claims 1 to 7, wherein the primary collimation optical element (23a) of the dichroic separation optical system (23) has an elongated shape along an expansion axis of the device (10, 10') transverse to the propagation axis (A).

10. The first optical unit (20) includes a plurality of primary light sources (21), 10. The illumination device (10, 10') of claim 9, wherein the dichroic separation optical system (23) comprises at least one collimation lens (23a) associated with the plurality of primary light sources (21) and configured to collimate the light emitted by each primary light source (21) around an individual one of the plurality of parallel propagation directions (A).

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